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TRANSACTIONS

OF THE

ROVAL SOCIETY OF EDINBURGH.
Vou. VII.

| BZ

eae eat

\.

EDINBURGH :

PRINTED FOR ARCHIBALD CONSTABLE & CO. EDINBURGH,
AND CADELL AND DAVIES, LONDON.

L615.

CONTENTS:

Or

VOLUME SEVENTH.

(Part First.)

I. Some Account of a Boy born Blind and Deaf, collected fron:
authentic Sources of Information; with a few Remarks.
and Comments. By Dugald Stewart, Esq; F. R. S.
Edin.. - - Page 5.
II. On the Vertical Position and Convolutions of certain
Strata, and their relation with Granite. By Sir
James Hall, Baronet, Pr. R. S. Edin. & F. B.S.

Lond. - = » "Q:
III. Remarks on the Transition Rocks of Werner.. By

Thomas Allan, Esq; F. R. S$. Edin. - 109°
IV. On the Revolutions of the Earth's Surface. Part I.

By Sir James Hall, Bart. = 139
V. On the Revolutions of the Earth’s Surface. Part II.

By Sir James Hall, Bart. - 169

VI. An Account of some Geological Facts observed in
the Faroe Islands. By Sir George Mackenzie,

| Baronet, Pr. Ph. Cl. R. S. Edin. 4 213.
VII. An Account of the Mineralogy of the Faroe Islands.
By Thomas Allan, Esq; FR. S. Edin. 3 229:

PART

CONTENTS.

(Part Srconp.)

WILL. Account of the Structure of the Table Mountain, and other
Parts of the Peninsula of the Cape. D:iawn up by Pro-
fessor Playfair, /rom Observations made by Captain Basil
Hall, R. N. F. R. S. Edin. ere Page 269
IX. Comparison of the North Polar Dist.nces of Thir-

ty-eight Principal Fixed Stars, on the st of Ja-
nuary 1800, as determined by Observations made

_-at Greenwich, Armagh, Palermo, Westbury, Dub-

lin, and Blackheath. By S. Groombridge, Esq.

Blackheath, F. R.S. Lond. .Communicated by
Dr Brewster, - 2

X. On the Optical Properties of Sulphaise of Cirbon;

Carbonate of Barytes, and Nitrate of Potash, with
Inferences respecting the Struciure of Doubly Re-
fracting Crystals. By David Brewster, LiL. D.
F. R.S. Edin. & F..A.S. E. =f

XI. An Account of Observations made by Lord Webb

XII.

ALI.

IV.

Seymour and Professor Play air, wpon some Geo-
logical Appearances in Glen Tilt, and the adja-
cent Country. Drawn up by Lord Webb Sey-
mour, - - | -

On certain Appearances observed in the Dissection
of the Eyes of Fishes. By James L. Drummond,

M. D. of Belfast. Communicated by Dr Thomas -

Brown, Professor of Moral Philosophy in the Uni-
versity of Edinburgh, - -
Observations on the Theory of Language. By
Henry Dewar, M. D. Fellow of the Royal as
of Physicians of Edinburgh, -

On the Diffusion of Heat at the Surface of the
Earth. By John Murray, M.D, F.R.S. Edin.

285

303

377

387

Ait

XV. On

CONTENTS.

XV. On a New Species of Coloured Fringes, produced
by the Reflection of Light between Two Plates of
parallel Glass of equal thickness. By David
Brewster, LL. D. F. R. S. Edin. & F. A. 8. E.

XVI. An Analysis of the Mineral Waters of Cromiia,
near Dunblane, and of Pitcaithly ; with general
Observations on the Analysis of Mineral Waters,
and the Composition of Bath Water and some

others. By John Murray, M. D. F. B.S. Edin. -
XVII. Biographical Account of the late John Robison, —

LL. D. F.R.S. Edin. and Professor of Natural
Philosophy in the University of Edinburgh. By
John Playfair, F. B.S. L. & E. &c.

-Appenprx, containing Lists of the Office-bearers and
Members elected since November 1812, -

Vil

435

445

495

541

DIRECTIONS ro tue Binper.

Plate I. II. III. IV. V. to front page 108.

—— VI. VII. VIII. 1X. to front page 212.

—— X. XI. (marked on the engraving Geology of Faroe, Plate I. & IT.)
to front page 220.

—— XII. Map of Faroe, to front page 229.

—— XIII. Sketch of Peninsula of the Cape, to front page 270.

aa a Granite Veins, to front page 278.

aan

after page 368.

Pa eet
—— XXII. after page 444.

SOME ACCOUNT

BOY BORN BLIND AND DEAF,

_ COLLECTED FROM AUTHENTIC SOURCES OF INFORMATION ;

WITH A

FEW REMARKS AND COMMENTS.

HE Memoir which I am about to submit to the conside-
ration of the Royal Society, relates to the melancholy
history of a boy who was born blind and deaf; and who, of
consequence, has derived all his knowledge of things external
from the senses of Touch, of Taste, and of Smell *

It is now considerably more than a year since I first heard of
this case from my very ingenious friend Mr Warnprop, Surgeon
in London; a gentleman whose scientific attainments and pro-
fessional skill it is unnecessary for me to mention to this audi-

ence.

* Since this paper was read before the Society, I have been enabled, by sub-
sequent communications, to enlarge it considerably. I have still reason to expect
farther information on the subject; but various circumstances make it desi-
rable, that so curious an article of philosophical intelligence should not be any
longer withheld from the public.

Vou. VII. A

he Py

y' 4 ACCOUNT OF A BOY

nece. The information which he then communicated to me
was extremely general ; but more than sufficient to excite all
my curiosity. “Ihave at present (says he) a patient under
my care, whose case is, I believe, wnique. It is a boy fourteen
years old, who was born blind and deaf, and of course dumb.
His senses of touch and smell have a wonderful degree of
acuteness ; for by these alone he has acquired a very accurate
knowledge of external things, and is able to know readily his
old acquaintances from strangers. The powers of his mind
are vigorous. He is evidently capable of reflection and rea-
soning, and is warmly attached to his parents. He has a most
delicate palate, and partakes only of the most simple food. I
have couched one of his eyes successfully; and he is much
amused with the visible world, though he mistrusts informa-
tion gained by that avenue. One day I got him a new and
gaudy suit of clothes, which delighted him beyond description.
It was the most interesting scene of sensual gratification I ever
beheld *.”

The first idea which struck me on receiving this intelligence
was, that so extraordinary a combination of circumstances
might perhaps afford a favourable opportunity of verifying or
of correcting, in an unequivocal manner, some of those de-
tails in CHESELDEN’s celebrated narrative, about which consi-
derable doubts have been lately entertained, in consequence of
their disagreement with the results of Mr Warr’s experience f.

. A

* This letter was dated October 4. 1810.

+ Mr Ware’s paper here alluded to, is to be found in. the Philosophical
Transactions for 1801. The argument which it has been supposed to afford
against CurseLpEN (founded on the case of Master W.) has always ap-
peared to me to prove nothing, in consequence of its aiming to prove too much.
Of this patient, (a boy who was restored to sight at seven years of age, after he
had been blind from very early infancy), we are told, that two days after the

operation,

BORN BLIND AND DEAF. 3

A repetition of such observations and experiments as Cue-
SELDEN made, would, I imagined, be greatly facilitated
by the total deafness of the patient in question ; the judg-
ments which a blind man is enabled to form of distances
(at least of small distances) by the ear, approaching,

A 2. point

operation, the handkerchief which was tied over his eyes having slipped upward,
he distinguished the table, by the side of which his mother was sitting. << It
was about a yard and a half from him; and he observed, that it was covered
with a green cloth, (which was really the case), and that it was a little far-
ther off than. he was able to reach.” |

Mr Ware afterwards informs us, that ‘* he held a letter before his patient,
at the distance of about twelve inches, when he told him, after a short hesita-
tion, that 2 was a piece of paper; that it was square, which he knew by its
corners, and that it was longer in one direction than it was in the other.”—
‘«* T then (says he) shewed him a’small oblong band-box, covered with red lea-
ther; which le said was red, and square, and pointed at once to its four cor-
ners. The observation, however, which appeared to me most remarkable,
was, that which related to a white stone-mug; which he first called a white
bason, but, soon after, recollecting rote said it was a mug, because it had:
a handle.”

Of the correctness idadh fidelity of this statement, I have not: the: slightest
doubt. But the only inference which can, with certainty, be deduced from it:
is, that the patient saw too well before the operation, to make his perceptions af-
terwards of any value for deciding the point in question. If he was able to re-
cognise a green cloth, and a piece of white paper, the very moment that the ban-
dage was removed, the degree of sight which he possessed previous to Mr
Wane’s acquaintance with him, must have been such as to furnish him with a va-
riety of sensations, quite sufficient to serve as materials for an imperfect visual.
language ;—a language, if not accurately significant of comparative distances
from the eye, at least fully adequate to convey, through the channel of that. or-
gan, the intimation of distance in general, or of what Berkexey calls outness ;-—
perhaps, also, some indistinct perception of diversities of visible figure. The
slightest, and, to us, the most evanescent shades of difference in these sensations,
will, we may be assured, become in the case of such an individual, signs of all
the various changes. in the state of surrounding objects, with which they have
any connection.

Having mentioned, on this occasion, the name of Mr Ware, I think it but
justice to him to add, that he does not appear to me to be himself disposed to

push

4 ACCOUNT OF A BOY

point of accuracy, very nearly to those which we are ac-
customed to form by. means of the eye. I had once occasion
to witness the precision with which Mr Goveu of Ken-
dal (by far the most intelligent and ingenious person, born
blind, whom I have happened to meet with) guessed at the di-
mensions of a large room, a few minutes after he entered it.
The error he committed was a mere trifle; not exceeding what

might

push his argument against CurseLpen so far as has been apprehended by some
later writers. In the following passages, he not only seems to admit the truth
of that optical principle which he has been generally understood to contro-
vert, but even points at the same explanation which I have already suggested,
of the apparent inconsistency between his own experience and that of his prede-
cessor.

“« I beg leave (says he) to add further, that on making inquiries of two chil-
dren, between seven and eight years of age, now under my care, both of
whom have been blind from birth, and on whom no operation has yet been per-
formed, I find that the knowledge they have of colours, limited as it is, is suf-
ficient to enable them to tell whether coloured objects be brought nearer to,
or carried farther from them; for instance, whether they are at the distance
of two inches or four inches from their eyes.

oe @ “© ime Se © « 2 6 6 =) 'e @ e's ge ele @ C's 6 e168 @ BO 02 « 8 © « © e ws 6 @

<¢T am aware, that these observations not only differ from those that are re-
lated of Mr Cursexpen’s patient, but appear, on the first statement, to oppose
a principle in optics, which I believe ts commonly and justly admitted, that the
senses of sight and feeling have no other connection but that which is formed
by experience; and therefore, that the ideas derived from feeling, can have no
power to direct the judgment, with respect either to the distance or form of
visible objects. It should be recollected, however, that persons who have ca-
taracts in their eyes, are not, in strictness of speech, blind, though they are
deprived of all useful sight. The instances I have adduced prove, that the
knowledge they have of colours is sufficient to give them some idea of dis-
tance, even in their darkest state. When, therefore, their sight is cleared by
the removal of the opaque crystalline which intercepted the light, and the co-
lour of objects is thereby made to appear stronger, will it be difficult or un-
philosophical to conceive, that their ideas of distance will be strengthened,
and so far extended, as to give them a knowledge even of the outline and
figure of those objects with the colour of which they were previously ac-
sjuainted ?”

BORN BLIND AND -DEAF. 5

might have been expected from the practised eye of a joiner or
ofan architect. It is not every operator, however dextrous in
his own art, who can be expected to attend sufficiently to these
collateral circumstances, or to be fully aware of the difficulty
which a blind person, suddenly put, in possession of a new
sense, must experience, when he attempts to distinguish, in his
estimates of distances, the perceptions of the eye from those
of the ear or of the nostrils. Something of the same kind, in-
deed, or at least strikingly analogous to it, happens. every mo-
ment to ourselves, in the judgments we pronounce on the beau-
ty or deformity of visible objects, without any suspicion, on
our part, how much these judgments are influenced by co-ex-
‘istent impressions of odour or of sound.

In consequence of this view of the subject, I had been led
by the first general outline which I received of this occurrence,
to indulge a hope that the peculiarities of the case might offer
some facilities which had not been before experienced, for esta-
blishing by palpable and incontestible proofs, the distinction
between the original and the acquired perceptions of sight ;
while, at the same time, the inability of the patient to an-
swer, by speech, the queries which might be proposed to him
with respect to the new world to which he had been so recent-
ly introduced, would, I conceived, by drawing the attention of
those around him to other signs of a less ambiguous -nature,
place the results of their observations beyond the reach of
controversy.—N. ot that, even upon tis supposition, every diffi-
culty would have been removed ; inasmuch as intimations con-
cerning distance may be occasionally conveyed to a blind man,
not only by the sense of smell, but by some of those /eedings
which are commonly referred to the sense of Touch *. In ob-

serving, -

* The blind man of Puiseaux (mentioned by Diweror) judged of his dis-
tance from the fire-place by the degree of heat; and of his approach to any so-

hid

6 ACCOUNT OF A BOY

_ serving, accordingly, the first visual perceptions even of a pa-
tient born deaf as well as blind, some very nice attentions.
would be necessary for ascertaining the truth. But what pro-
portion do these bear to the numerous and refined precautions
which become indispensable, where the patient is reminded by
every query which is addressed to his.ear, of the distance and
relative position of the questioner ? — might Diperot
say,—* Preparer et interroger un aveugle né, n "etit point été
une occupation indigne des talens réunis de Newton, Des-
carTES, Locker, et Lernirz.”—I mention this, because,
from the great degree of perfection to which this branch of
surgery has been lately carried, the increasing number of such.
cases may be expected to multiply daily the opportunities of
philosophical experiment ; and it is of importance, that those _
who may have the good fortune to enjoy them, should be ful-
ly apprized of the delicacy and the complexity of the pheno-
mena which they have to observe and to record *.

In giving way to these speculations, I had proceeded on the
supposition, that the blindness of the patient was complete ;
not sufficiently attending to (what was long ago remarked by
CueseLpEeN) the qualified sense in which the word blindness is
understood’ by surgical operators. Though this gentleman.
was blind,” (says CurseLDEN, speaking of the patient whose

case he has so well described), “ as is said of all persons who
“ have ripe cataracts, yet they: are never so blind, from that
cause,

lid obstacle, by the action or pulse. of the air upon his face. The same, thing is
recorded of Dr Sanperson by his successor Mr-Cotson. | wilie

r

im: For the assistance of those to whom such a subject of observation may oc-
eur, some judicious hints.are suggested in the Lettre sur les Aveugles a Pusage de

ceux qui vorent.

BORN BLIND AND DEAF. 7

cause, but that they can discern day from night ; and, for the
most part, in a strong light, distinguish black, white, and scar-
let ; but they cannot perceive the shape of any thing. Thus it
was with this young gentleman.” The case I have since found
to have been the same, and in a degree considerably greater,
with the boy who has given occasion to this memoir; inso-
much that his condition seems to have approached much near-
er to that of Mr Warr’s patient than to that of CursELpEN’s.
“ At the time of life’ (Mr Warprop observes) when this boy
began to walk, he seemed to be attracted by bright and
dazzling colours ; and though every thing connected with his
history appears to prove that he derived little information from
the organ of sight, yet he received from it much sensual grati-
Jication.

“He used to hold between his eye and luminous objects,
such bodies as he had found to increase, by their interposi-
tion, the quantity of light; and it was one of his chief amuse-
ments, to concentrate the sun’s rays by means of pieces of
glass, transparent pebbles, or similar substances, which he
held between his eye and the light, and turned about in va-
rious directions. These, too, he would often break with his
teeth, and give them that form which seemed to please him
most. There were other modes by which he was in the ha-
bit of gratifying this fondness for light. He would retire to
any out-house, or to any room within his reach, shut the win-
dows and doors, and remain there for some considerable time,
with his eyes fixed on some small hole or chink which admit-
ted the sun’s rays, eagerly catching them. He would also, du-
ring the winter-nights, often retire to a dark corner of the
room, and kindle a light for his amusement. On these occa-
sions, as well as in the gratification of his other senses, his
countenance and gestures displayed a most interesting avidity
and curiosity.

“6 It

& ACCOUNT OF A BOY

“ It was difficult, if not impossible, to ascertain with preci-
sion, the degree of sight which he enjoyed; but from the
preternatural acuteness which his senses of touch and smell
had acquired, in consequence of their being habitually employ-
ed to collect that information for which the sight is peculiarly
adapted, it may be presumed with confidence, that he derived
little, if any assistance from his eyes, as organs. of vision. The
appearances of disease, besides, in the eyes, were such as to
render it in the highest degree probable, that they enabled him
merely to distinguish colours, and. differences in the intensity

of light.”

From this history of the patient’s previous situation, it ap-
peared evident that his case was not of such a sort as to afford
an opportunity of bringing CuEsELDEN’s conclusions to the test.
On the contrary, his habits of observation, and even of experi-
ment, on his visual sensations, combined with the singular
acuteness and discrimination of his olfactory perceptions, ren-
dered it almost certain that the results of a successful operation
on his eyes would be similar to those described in Mr Ware’s
paper. Such, accordingly, has, in point of fact, been the issue
of this new experiment ;—in describing which, however, I
must, remark, to the honour of Mr Warprop, as a cautious and
philosophical observer, he has abstained from drawing the
slightest inference to the prejudice of CHEsELDEN’s statement ;
—a, statement which nothing can disprove till a case shall oc-
cur of a patient cured of total, or almost total blindness ; and
till this case shall be observed and examined with all the
nice precautions which so delicate and complicated a pheno-
menon demands.

BORN BLIND AND DEAF. 9

I shall not follow Mr Warnror through the details of the
surgical operation ; in performing which, he was forced, by the
peculiar circumstances of his patient, to employ a mechani-
cal apparatus, for fixing his body and head in an immoveable
posture. I flatter myself that he will soon communicate to the
public a history of the whole case; and I should be sorry to
deprive his memoir of any part of its interest. The general
results alone are connected with the objects which I have at
present in view ; and these I shall take the liberty to state in
Mr Warpror’s words.

«“ When the operation was finished, he expressed great sa-
tisfaction ; gazed around him, and appeared to distinguish ob-
- jects. This, however, could not be ascertained in a manner
quite satisfactory, as it would have been prejudicial to his re-
covery to make any experiments; but it could be perceived
from the change in the expression of his countenance. His
eye, accordingly, being covered up, he was carried home, and
put to bed in a dark room; after which he was bled in the
ALM. » 6 92 |

“ On the fourth day I examined the eye accurately, and ob-
served the state of his vision. I found that the crystalline
lens (which had been pushed upwards and backwards) had
altered its situation since the operation, and could be again di-
stinguished, covering about one-fourth of the upper edge of
the pupil. The other part of the pupil was quite transparent,
_ and all the blood which was effused into the anterior chamber
during the operation was now absorbed. On making trial if
he could distinguish any object, he readily discovered a book,
or any similar thing, placed on the coverlet of the bed ; and in

many of his attempts, he seemed to judge pretty accurately of
their distance.

Vou. VII. B “ On

10 ACCOUNT OF A BOY

“ On the fifth day he got out of bed, and was brought into
a room having an equal and moderate light. He walked about
the room readily ; and the expression of his countenance was
much altered, having acquired that look which indicated the
enjoyment of vision. Indeed, he always walked about, before
the operation, with much freedom ; and even on a very rugged
and unequal road, he did not appear to suffer in the least from
any jolting.

““ He appeared well acquainted with the furniture of the
room, having lived in it several days previous to the opera-
tion ; but though he evidently distinguished, and attempted to
touch objects which were placed before him, judging pretty
accurately of their distances, yet he seemed to trust little to
the information given by his eye, and always turned away his
head, while he felt accurately over the whole surfaces of ae
bodies presented to him.

“ On the sixth day he appeared stronger, and amused him-
self a good deal with looking out of the window, seeming to
observe the carts and carriages which were passing in the
street. On putting a shilling on the middle of a table, he in-

stantly laid his hand upon it.
“ On the seventh day the inflammation was nearly gone,

and he observed a piece of white paper of this size be) lying

on the table. I took him into the street, and he appeared
much interested in the busy scene around him ; and at times
seemed frightened. A post supporting a scaffold, at the dis-
tance of two or three yards from him, chiefly attracted his no-
tice, and he timorously approached it, groping, and stretching
out his hand cautiously until he touched it.”

Of these very valuable facts Mr Warpror has left us to form
To myself, I must own, that, due allow-

our own judgment.
ances

BORN BLIND AND DEAF. 11

ances being made, 1s?, for the visual sensations which were fa-
miliar to the patient from his infancy, and, 2¢/y, for the in-
timate and accurate acquaintance which he had acquired of
things external, by a comparison of the perceptions of smell
and of touch, the result appears, on the whole, as favourable
as could reasonably have been expected, to the Berkeleian
theory of vision: Nor am I able to observe a single circum-
stance of any importance, which is not perfectly reconcilable
with the general tenor of CHEsELDEN’s narrative *.

B2 The

* I have said, the “ general tenor of Curseipen’s narrative,”—for there are
some expressions ascribed by him to his patient, which must, in my opinion, be
understood with a considerable degree of latitude. And, indeed, if we reflect
for a moment on the astonishment and agitation likely to be produced by the
sudden acquisition of a new sense, we cannot fail to be satisfied, that the autho-
rity of the narrative rests much more on the conviction which the whole circum-
stances of the case had left on CureseLpEn’s own mind, than on the verbal an-
swers (intelligent and satisfactory as most of these are), which his patient gave
to the queries of his attendants. It was for this reason, among others, that I
before hinted at the advantages which he would have enjoyed, in observing and
describing the facts before him, if his patient had been deaf as well as blind, like
the subject of this memoir.

Of one expression employed by Cuzsripen’s young man, I think it proper to
take some notice here, on account of the stress which Mr Wane seems disposed’
to lay upon it, as at variance with the language used by his patient Master W.
“* When the young gentleman first saw, (says Cuzsz.pen), he was so far from
making any judgment about distances, that he thought all objects whatever
touched his eyes, (as he expressed tt), as what he felt did his skin.” It: seems to
me inconceivable, that Cueseipen could have meant this last phrase to be inter-
preted literally ; for the thing which it implies is altogether impossible. The
most obvious meaning which the words convey is, that the object seemed to be
contiguous to, or tn contact with, the cornea; whereas the truth is, that the office
of the cornea is merely to transmit the rays to the retina, which it does without
itself receiving any sensible impression of which we are conscious. Mr Smirx,.
too, has objected to this mode of speaking, though on grounds somewhat different.
“ When the young gentleman said, (1 quote Mr Smirn’s words), that the objects

which.

12 ACCOUNT OF A BOY

The strong impression which Mr Wanre’s paper has lately
made on the public mind, and the support which it is probable
many readers will imagine that the argument against CuxrseL-
DEN derives from the observations of Mr Warprop, will ac-
count sufficiently for the length to which the foregoing remarks
have extended : Or, if any farther apology be necessary, I trust

that

which he saw touched his eyes, he certainly could not mean that they pressed
upon or resisted his eyes; for the objects of sight never act upon the organ in
any way that resembles pressure or resistance. He could mean no more than
that they were close upon his eyes, or, to speak more properly, perhaps, that they
were in his eyes +.” Mr Suirn’s idea in this last clause, was, I presume, that the
local situation of the object was referred by the patient to the retina, where the
image of the object is painted. Now, I confess, for my own part, that although
I perfectly agree with Mr Smrrn in his criticism on Curseipen, I am by no
means satisfied, that the emendation which he has suggested of the young gen-
tleman’s description is unexceptionable; for it does not appear to me, that the
impression of a moderate light on the retina, is accompanied with any perception
of the part of the body on which the impression is made. Where the light, in-
deed, is so powerful as to produce pain, the case comes to be different ; for a sen-
sation of touch is then united with the proper sensations of sight ; and it is cha-
racteristical of all sensations of touch, that they are accompanied with a percep-
tion of the local situation of their exciting causes. ‘This, however, it is well
known, does not take place with respect to the sensations of smell and of sound ;
nor do I imagine it to take place, prior to experience, with respect to the sen-
sations received by the eye. And, therefore, if a patient, in such circumstances,
should be led, by his first visual perceptions, to connect them locally with the or-
gan by which they are received, I should be inclined rather to ascribe this to
concomitant feelings of pain, (produced by the recent operation, or by the too
sudden impression of a strong light), than to any of those sensations which are
exclusively appropriated to the sense of sight. But this discussion it is un-
necessary for me to prosecute at present, as the opinion we may happen to form
with respect to it, (whatever that opinion may be), can never affect the truth of
that clause in CueseLpen’s statement, in which he asserts, upon the evidence of
his own observations, that ‘‘ when his patient first saw, he was unable to form any
judgment about distances.” The remainder of the sentence is only a loose and
unintelligible comment of the young man on this simple fact.

+ See an Essay on the External Senses, by Apam Smitu, LL.D. (published among his posthumous
papers.)

BORN BLIND AND DEAL. 13

that allowances will be made for my anxiety to obtain from
the enlightened Operators of the present times, an additional
contribution of evidence in eonfirmation of one of the most
beautiful, and, at the same time, one of the most important
theories of modern philosophy.

Mr Waroprop afterwards enters into some circumstantial
ual very pleasing details with respect to an incident alluded to
in a passage which I have already quoted from one of his let-
ters ;—the joy manifested by his patient when he was first
dressed in a suit of gaudy clothes... From this part of his me-
moir I shall only transcribe a few lines. ‘ His partiality to
colours seemed. to depend entirely on their comparative bril-
liancy. He in general liked objects that were white ; and still
more particularly those of a red colour. A white waistcoat or
white stockings pleased him exceedingly ; and he gave always
a decided preference to yellow gloves. One day. I observed
him to take out of his pocket a bit of red sealing-wax, which
he had aan for the beauty of its colour. ator. sain eorots co a): os
A pair of Prsesoeiblactiem were given him, with a view of les-
sening the influence of the bright sun on the still irritable eye ;
and i om them also he derived great pleasure. Indeed, when he
first put them on, he laughed aloud with delight.”

- A few weeks after I had been favoured by Mr Warpnor
with his first communication on this subject, I learned, through
a different channel, that his patient had left London ; and,
as I had never happened: to make any inquiries about
his connections, or the place of his: nativity, I had abandoned
for many months all expectations of farther ‘intelligence with
respect to him ; when he was most unexpectedly and agreeably.
recalled: to my recollection by a letter which I received. last
week from Mr Professor GLenn1e, the very learned and worthy

successor

14 ACCOUNT OF A BOY

successor of Dr Bearrie in his academical chair at Aberdeen:
In this letter Mr Grewnir incloses “ An Account of James
Mircuett, a lad in the county of Moray, born blind and
deaf;” drawn up, at Mr Guenwie’s request, by a neighbour-
ing clergyman. From the narrative it appears, that this is
the very patient who was formerly under Mr Warpror’s
care; and it appears farther, that although his blindness
returned again, not long after the operation was performed, the
peculiarities of his case still continue to present, under a new
and very different form, a subject of examination and inquiry,
not less interesting than if Mr Warpror’s exertions in his fa-
vour had been rewarded with permanent success.

A short extract from Mr Giewnnir’s letter will form the best
introduction I can prefix to the history which is to follow.

“¢ T send you inclosed an account of a clergyman’s son who
was born deaf and blind. The account is imperfect as yet ;
but it is an accurate answer to a series of questions which I put
to the clergyman who has taken the trouble to draw it up. As
he has very obligingly offered to answer any more queries that
I make, I have prepared a good many additional questions,
that the present state of the young man’s mind may be ascer-
tained with as much accuracy as possible. Much light might
have been thrown on the mental faculties, if accurate experi-
ments and observations had been made on patients in such cir-
cumstances as this unfortunate young man. [| intend, if it be
possible, to visit him durmg our summer vacation; but
I am sensible, that little can be done in such a case, even
in a visit of some days, compared with what may be ac-
complished by his constant attendants, if we could teach
them to make the proper experiments. For this purpose,
the only thing I can think of is, to direct the mother and
sister to have recourse to the narratives of some instances not

dissimilar,

BORN: BLIND AND DEAF. 15

dissimilar, that their attention may be drawn to their own me-
thods of communication, which, having become habitual, escape
their notice. But I must forbear entering on a minute discus-
sion of this case, which appears to me very interesting.” .«. .

es e e e e e e e e e e e J ° e e e s e

Before I proceed to read the paper alluded to in the forego-
ing extract, I think it proper for me to mention, that I have
not been favoured with the name of the writer, and that I must
therefore request, it may not be considered, in its present form,
as a fair subject of discussion or of criticism. That it bears
strong marks of uncommon intelligence and discrimination in
the observer, must be universally acknowledged ; but it reached
me so very lately, that I have not had time to solicit, through
Mr Guenniz, the author’s permission to communicate it to the
Society *.

* I have since learned from Mr Gurnniz, that the paper in question was
written by the Reverend Tuomas Macrartane, minister of Edinkillie, in the
presbytery of Forres. Mr Guennie adds a sentence which I beg leave to quote,
as some apology for the liberty I now take in mentioning Mr Macraruane’s
name without his express authority. I certainly would not have presumed to
do so, if I had not been fully persuaded, that all who are competent to form a
judgment on such subjects, will feel much indebted to him for his very interest-
ing and satisfactory statement.

“¢ As I communicated to Mr Macrartane your wish to print his memoir, I
take for granted that he has no objection to your making this use of his papers,
although he has not expressed his sentiments explicitly to this purpose.”

Answers

16 ACCOUNT OF A BOY

Answers to some Queries addressed to a Clergyman in the Coun-
ty of Moray, by Mr Professor Guenniz of Marischal Col-
lege, Aberdeen, with respect to James. MitcuHety, a lad sire
teen years of age, who was born blind and deaf.

“ The subject of this brief notice is the son of the Reverend
Donarp Mrrcuext, late minister of Ardclach, a Highland pa-
rish, lying on the banks of the Findhorn. He was born 11th
November 1795, and is the sixth child of his parents, being
the youngest except one. All his brothers and sisters, (as
were also his parents), are perfectly free from the deficiency of
sight and hearing, which occurs in his case; and are healthy
and well formed. His mother, who is an intelligent and sen-
sible lady, very early discovered his unfortunate situation: she
noticed that he was blind, from his discovering no desire
to turn his eyes to the light, or to any, bright. object;
and afterwards, (in his early ‘infancy also), she ascertained
his being deaf, from ‘the circumstance that’ no noise, how-
ever loud, awakened him from sleep. As he grew up,
he discovered a most extraordinary acuteness of he senses
of touch and smell; being very soon: able, by these, to di-
stinguish strangers’ from the members of his own family, and
any little article which was appropriated to himself, from
what belonged to others. In his childhood, the most notice-
able circumstance relating to him, was an eager desire to strike
upon his fore-teeth any thing he could get hold of; this he

would do for hours ; and seemed particularly gratified if it was
a

BORN BLIND AND DEAF. 17

a key, or any instrument that gave a sharp sound when struck
against his teeth. This would seem to indicate that the audito-
ry nerve was not altogether dormant... .......+0.4..

“ Tn 1808, and again in 1810, his father carried him to Lon-
don, where operations were performed upon his eyes by the
most eminent practitioners, with very little, or rather with no
(permanent) success *; while an attempt that was made at the
same time, to give him the sense of hearing, by piercing the
tympanum, totally failed. |

“ Such is the brief history of this poor lad: it remains now to
give some account.of his appearance, behaviour, the feelings by
which he seems to be actuated, the manner in which he con-
veys his desires, and the methods by which he is managed.

“ 1. His countenance, notwithstanding his unfortunate de-
fects, does by no means indicate fatuity; nay, the lineaments
of thought are very observable upon it. His features at times,
(in church, for instance, and during the time of family prayer),
are perfectly composed and sedate; when sensible of the pre-

sence

_ * That one of these operations was attended with considerable success in the
Jirst instance, appears not only from the extracts already copied from Mr War-
DRopP’s narrative, but from the following passage in a letter to that gentleman
from the Reverend Mr Mircuert. This letter is dated 5th October 1810,
about a month after Mr Mrrcue x and his son had left London, to return home
by sea.

_ James seemed much amused with the shipping in the River, and till we
passed Yarmouth Roads. During the rest of the passage, we were so far out at
sea, that there was little to attract his notice, except the objects around him on
RGIS. outs 5 J Us PRD) 12183, b FE AE ITO, 28h, NT, LOT DOCOT: Et g BOIL,
His eye is now pretty free of the redness it had when he left town, and the
cataract in the same moveable state, sometimes covering more and sometimes
less of the pupil. ‘Though his sight is not much increased since we left London,
yet I am perfectly satisfied that what he has got is of essential service.”

Vou. VII. peal &

18 ACCOUNT OF A BOY

sence of a stranger, or of any object which awakens his curio-
sity, his face appears animated; and when offended or enra~
ged, he has a very marked ferocity of look. He is (for his
age) of an athletic form, and has altogether a robust appear-
ance, |

“« 2. He behaves himself in company with much more pro-
priety than could be expected ; a circumstance owing undoubt-
edly to the great care of his parents, and of his elder sister.
He feeds himself. When a stranger arrives, his smell imme-
diately and invariably informs him of the circumstance, and
directs him to the place where the stranger is, whom he pro-
ceeds to survey by the sense of touch. In the remote situation
where he resides, male visitors are most frequent ; and, there-
fore, the first thing he generally does, is to examine whether
or not the stranger wears boots; if he does wear them, he im-
mediately quits the stranger, goes to the lobby, feels for, and
accurately examines his whip ; then proceeds to the stable, and
handles his horse with great care, and with the utmost seem-
ing attention. It has occasionally happened, that visitors have
arrived in a carriage, and, on such occasions, he has never
failed to go to the place where the carriage stood, examined
the whole of it with much anxiety, and tried innumerable
times the elasticity of the springs. In all this he is undoubt-
edly guided by the smell and touch only, without any assist-
ance from sight ; for, going to call lately for his mother, I pass-
ed him, near to the house, within a few feet, without his no-
ticing me in the least; and offering him a. glass of punch after
dinner, he groped for it, as one in total darkness..

“ 3. The feeling by which he appears to be most power-
fully actuated, (at least to a stranger), is curiosity, or an anxi-
ous desire to make himself acquainted. with every thing that is
new to him. He appears to feel affection to those of his-fa-

mily

BORN BLIND AND DEAT. 19

mily very strongly ;—discovered extreme sorrow on account of
his father’s death; laid himself upon the coffin, after his fa-
ther’s corpse was put into it, apparently in much grief; went
frequently to his grave, and threw himself upon it, whilst he
gently patted the turf, and bemoaned himself greatly. He is
likewise capable of feeling mirth, and frequently laughs hearti-
ly. He is highly gratified by getting new clothes; and as
tearing his clothes is the most usual expression of his anger, so
the punishment he feels most is being ‘obliged to wear them
after he has torn them. He is pee to anger, upon being
crossed in any of his desires, or when he finds : any of ut
clothes, or articles with which he amuses himself, removed
from the chest in which he keeps them.

“ 4, Respecting the: manner in which he conveys his feel-
ings and desires, I am: much at a loss:to give the rab
; that might be expected. It is certain tliat those of his family
know perfectly in what temper of mind he is, and what he
wants to have; arid these intimations: he conveys to them: in
the presence of strangers, without these: last: being sensible of
his doing so. When he is hungry, he approaches his mother
or sisters, touches them in an expressive manner, and points
towards: the apartment: where: the victuals are usually kept.
If he wants: dry stockings, he: points to his legs; and-in a si-
milar way,.intimates his wishes upon other occasions. A pair
of shoes were lately brought to him, and on putting them
on: he: found them too small.. His: mother then took them,
and» put: them: into’ a; small’ closet; soon after a thought
seemed: to: strike him,, and he coritrived. to obtain the
key: of the closet; opened: the: door, took the shoes; and
put them upom the: feet of a young: lad who: attends: him;
whom they suited: exactly; This:action of his: implies con=

C2 siderable

20 ACCOUNT OF A BOY

siderable reflection, and shews that he must have made
some accurate examinations, though unnoticed at the time.
When he is sick and feverish, which sometimes happens, he
points to his head, or takes his mother’s hand and places it op-
' posite to his heart, seemingly with an intention that she may
observe its beating more quickly than usual. He never at-
tempts to express his feelings by utterance, except when an-
gry, when he bellows in a most uncouth manner. Satisfaction
or complacency he expresses by patting the person or object
which excites that feeling. His smell being wonderfully acute,
he is frequently offended through that sense, when other per-
sons near to him smell nothing unpleasant; he expresses his
dissatisfaction on such occasions, by putting his hand to his
nose, and retreating rapidly. His taste seems also to be ex-
quisite, and he expresses much pleasure by laughing and
smacking his lips, when any savoury victuals are laid before ~
him. |

“5. His father, when alive, was at much pains in direct-
ing him, as his mother still is; but his elder sister seems to’
have a much greater ascendancy over him, and more power of
managing him than any other person. Touching his head
with her hand seems to be the principal method which she
employs in signifying her wishes to him respecting his con-
duct ; this she does with various degrees of force, and m dif-.
ferent manners; and he seems readily to understand the inti-
mation intended to be conveyed. In short, by gratifying him
when he acts properly, and withholding from him the objects:
of his complacency when he has done amiss, he has been
taught a sense of what is becoming in manners, and proper in
conduct, much stronger than it could be otherwise believed,
that any person, in. his singularly unfortunate situation, could
acquire.”

SINCE

BORN BLIND AND DEAF. 2k

Since the foregoing narrative reached me, I have had the
good fortune to receive a most important and authentic sup-
plement to it, from Dr Joun Gorpon ; a gentleman, on whose
recent admission into our number, I beg leave to congratulate
the Society. Having communicated to oa on the suggestion
of our colleague Dr J oun Tuomson, Mr Guennir’s letter with
the inclosed statement, he most obligingly undertook, on a
very short notice, to add to it whatever particulars relative to
the same subject had fallen under his own personal knowledge.
Of the ability with which he has executed this task, amidst his
various professional avocations, I have no doubt that the So-

ciety will think as highly as I do.

Supplement to the foregoing Account of James Mircuet, by
Joun Gorpon, M. D.

“The boy who is the subject of the above mteresting com-
munication, was brought by his father to visit me at Forres in
the autumn of 1808.

“I found on examination that he had a cataract in each eye.
Ir both, the crystalline lens had a pearly colour, and appeared
to be ofa firm consistence ; but the pupils exhibited very per-
ceptible contraction and dilatation, when the quantity of light
was suddenly increased or diminished. The auricle or exter-
nal part of each ear, and the tube leading from it to the tym-
panum, were of their natural size and.form; and nothing un-.

usual.

72 ACCOUNT OF A BOY:

usual could be discovered in the conformation of the parts
about the fauces.

“ From the motions which were produced in the iris, by va-
rying the quantity of light admitted to the eyes, I should alone
have been inclined to hope, that the retina was not altogether

wanting, and to have urged the propr iety of attempting to re-
move'the opaque lens me the axis of vision by a surgical ope-
ration. But the following circumstances served to confirm
this opinion. In the fie. place, Mr Mrrcuetx informed me,
that he had often observed his son, sitting for an hour at a
time, opposite to a, small hole in the south wall of a hut ad-
joining to the manse, so as to receive the beams of the sun,
which, shone through the hole during part of the forenoon, di-
rectly on his eyes. The boy ciel have no other motive for
placing himself in this situation, but to enjoy a certain agree-
able sensation of light ; and it is not improbable, that. the par-
ticular pleasure which he seemed to derive from the light of
the sun, admitted in this manner, arose from the eyes having
been rendered more susceptible to impressions, by being pre-
viously directed to the darker parts of the hut. Secondly, I
observed, that he very frequently turned his face towards the
window of an apartment, and then pressed. his finger forcibly
backwards between. the eyebrow. and upper eyelid of one of
his eyes, so as to occasion a slight degree of distortion, and a
very disagreeable appearance of protrusion of the ball. I.sup-
posed, that when he compressed the eye-ball in this manner,
either some change in the organ. was produced, by which ,he
obtained a more distinct i impression from the light of the win-
dow, or else that the pressure on the retina Hala oceasioned.
the sensation of a luminous ring or spot, which he had plea-
sure in contemplating. When I put my silver pencil into his
hand, after turning it quickly round in the points of his fingers,
and

BORN BLIND AND DEAF. 23

and applying it to his nose, lips, and the tip of his tongue,
he rattled it smartly between his fore-teeth ; and his father as-
sured me that he did so with every hard substance which he
could convey to his mouth, and that he seemed to have pleasure
in repeating this motion with metallic bodies in particular. This
circumstance led me to conclude, that vibrations communicated
through the solid parts of the head, were capable of producing
in him, to a certain degree, the sensations of sound. But these
sensations were obviously so very weak, when compared with
those which persons who are affected with obstruction in the
eustachian tubes, can at all times enjoy through the medium
of the bones of the head, that I could not but fear that the
deafness in this case, depended not on any want of air in the
tympanum, but on some great deficiency, or radical impertec-
tion in the structure of the auditory nerve. Although, there-
fore, no harm could result from piercing the membrane of the
tympanum, I did not expect that the sense of hearing would
be much improved by this operation.

“ With this opinion of the boy’s situation, I earnestly re-
commended. it to his father to carry him to London, and to
place him under the care of Mr Ware and Mr Asrizy Coo-
per, in order that the operation of couching or extraction
might be performed on one or both eyes, and that the mem-
brane of the tympanum in each ear might be perforated.

“ In the course of a few weeks, Mr Mircuett repaired with
his son to London. Mr Astiey Coorrr pierced the mem-
brane of each tympanum, but without the slightest benefit ;
and, at the same time, the late Mr Saunpers operated with the
needle on the left. eye, and, it is to be presumed, used every
effort which the violent struggles of the boy would permit, to
depress the cataract ; but not the least advantage resulted from
the operation. |

« In

Q4 ACCOUNT OF A BOY

“ In the summer of 1810, several months after his return
from London, young Mrrcuett was again brought by his fa-
ther to visit me at Forres. When I placed him in a chair be-
fore me, and took hold of his head, with a view to examine his
eyes, his situation seemed immediately to recall to his memo-
ry the painful operations with which this examination had been
formerly succeeded, and he withdrew from me in his chair,
panting as from a sudden alarm. By patting him gently on
the cheek, however, his fears were quickly allayed. The cata-
ract of the left eye, into which the needle had been introduced,
had lost its white colour, and seemed as if broken down ; but
still the lens remained opaque, and he was in every respect as
blind as when I first saw him. The pupil, however, of each eye
was very distinctly enlarged when I placed my hand before
his face, and it again contracted when the hand was removed ;
and I observed witli great satisfaction, every time I practised
this experiment, that verb the quantity of light admitted to
the eye was increased, the boy expressed his pleasure by a
smile. The cataract of the right eye had the same appearance
of firmness as before, and I therefore still entertained hopes,
that it might be practicable to remove it entirely by the ope-
ration of extraction. On stating this opinion to Mr Mircuetz,
to the honour of whose memory it ought to be remarked, that
he displayed at all times the most earnest anxiety to alleviate
the sad condition of his child, he immediately resolved to visit
the metropolis once more ; and, in compliance with my request,
to entrust the treatment of his son, entirely to the judgment

and practical skill of my friend Mr Warprop. In a few weeks
Mr Warprop wrote to me, that having resolved to attempt ex-
tracting the cataract from the right eye, he had endeavoured,
by means of powerful machinery, as well as the aid of nume-
rous assistants, to fix the boy’s a in a position sufficiently

steady

BORN BLIND AND DEAF. 25

steady for so delicate an operation ; but that his struggles were
so violent as to render every effort for this purpose ineffectual.
The attempt at extraction was therefore relinquished; but,
soon afterwards, I had the satisfaction of being informed by
Mr Warnpror, that he had so far succeeded, by the use of the
couching-needle, in breaking down the cataract, and removing
it from the axis of the eye, that his young patient had been
able to see a very small object of a white colour, when placed
on a table before him. This partial success from Mr War-
prop’s operation, led me to anticipate, with no small confi-
dence, a still further improvement in young MircuHe.1’s vision;
from the gradual absorption of some of the broken fragments
of the opaque lens or its capsule. But in this expectation I
have been altogether disappointed. In the month of June last,
I saw him repeatedly at his father’s house, and had ample op-
portunity of observing his motions with attention. When he
approached any object, such as a wall, a cart, or a carriage, so
large as to be in part interposed between his eyes and the ho-
rizon, he seemed to discover its vicinity by the interception of
the light which it occasioned alone, and cautiously put out his
hands before him, to feel for that with which he was already
almost in contact. But he did not appear to be at all capable
of perceiving minute objects, nor of distinguishing in the
slightest degree between one colour and another. His powers
of vision, therefore, so far from continuing to improve since
the successful result of Mr Warprop’s operation, have but too
plainly undergone a degree of failure. A fragment of the sub-
stance of the ea, or of its capsule, very erhiee and opaque,
may still be seen behind one-half of the pupil, and through the
lower half, a slighter opacity is very perceptible in the parts
situated farther back *.

Vou. VII. D “ On

es 5s «< You will perceive, from the account of the state of the cataract,

immediately after the operation, that a part of the opaque body still hung over
&

26 - ACCOUNT OF A BOY ~

* On the whole, Iam of opinion, that if this unfortunate,
but very interesting boy, should at any future period be indu-
ced, either by being informed through the medium of some
peculiar language, of the object in view, or from his increased
knowledge in the kindness and good intentions of his relations,
to submit patiently to the operation of couching or extraction,
either of these operations ought to be repeated on one or both
_ eyes. At the same time, it must be confessed, that, since the
attempts of this kind already made, have not only failed to
communicate to him the powers of distinct vision, but also the
perception even of the more striking differences in the degrees
and kinds of light, there is but too much reason to fear, that
the optic nerve, although not entirely deficient, is yet imper-
fect in its structure.

“ I have but little to add to the full account which is given in
Mr Guewniz’s communication, of young Mrrcueu’s general ap-
pearance and conduct. The knowledgewhich he has derived from
the senses of Touch, Taste and Smell, seems fully as extensive,
as what any person of the most perfect faculties might be sup-
posed to acquire, if he could by any contrivance be prevented
from using his eyes and ears for the same period of time, from
the moment of his birth, and in the same retired situation of
the country. The train of his thoughts seems to be regulated
by the same principles as that of the soundest minds. His ac-
tions neither indicate incoherence nor fatuity ; but every thing
he does, appears capable of being easily traced to rational mo-

tives.

a portion of the pupil. I have been told lately, that he now sees little or none.
If this be the case, I suspect it must have been from the cataract passing over
the whole of the pupillar opening, instead of being altogether absorbed, or re-
maining out of the way, as might have been expected.”
Extract of a letter from Mr Warprop to Mr Stewarr,
(dated August 10. 1812.)

BORN BLIND AND DEAF. pas 4

tives. His more pleasurable sensations are obviously enjoyed
from the senses of Taste and Smell; and, indeed, I have never
observed any thing disagreeable in his manner, except the
keenness and voracity with which he devours his food. But
he derives amusement also from the sense of Touch. His fa-
ther told me, that he had often remarked him, employing
many hours in selecting from the bed of the river, which runs —
within a few yards of the house, stones of a round shape, near-
ly of the same weight, and having a certain degree of smooth-
ness. These he placed in a circular form on the bank, and —
then seated himself in the middle of the circle.

“« There is a certain range around the manse which he has
minutely explored by his organs of Touch, and to any part of
this space he seems to walk, when he pleases, fearlessly and
without a guide. I believe his range does not yet extend be-
yond two hundred yards in any direction; but there is proba-
bly not a day elapses, during which he does not cautiously feel
his way into ground which he had not explored before ;
and thus gradually extends his yet very circumscribed field of
observation. It was m one of these excursions of discovery,
that his father observed him with horror, creeping on his
hands and knees along a narrow wooden bridge which crossed
the river, at a point where the stream is deep and rapid. He
was immediately arrested in his progress; and as his father
wished to discourage him from hazarding so perilous an at-
tempt again, a servant was directed to plunge him, as soon as
he was secured, once or twice into the river. This measure
has had the desired effect. | |

“From a similar solicitude about his safety, the servants
had been enjoined to prevent him from visiting the stable,
which he never fails to do, the instant he has discavered by

D2 the:

28 ACCOUNT OF A BOY:

the presence of an additional whip in the lobby, that the per-
son who has arrived has brought a horse with him. | I have
been assured, however, that after his wishes in this respect had
been repeatedly thwarted, he at last had the ingenuity to lock
the door of the kitchen on the servants, in the hopes that he
might then accomplish his visit to the stable unmolested. —

“ His father once told me an anecdote of him, which dis-
plays in a very striking manner, both the retentiveness of his
memory, and the benevolent feelings of which he is suscepti-
ble. He had received a severe wound in his foot, and during
its cure, he usually sat by the fire-side, with his foot resting on
a small foot-stool. More than a year afterwards, a servant-boy
with whom he used to play, was obliged to confine himself to
a chair from a similar cause. Young Mircue.u perceiving,
that his companion remained longer in one situation than he
used to do, examined him attentively, and seemed quickly to
discover by the bandages on his foot, the reason of his confine-
ment. He immediately walked up stairs to a garret, sought
out, amidst several other pieces of furniture, the little foot-
stool which had formerly supported his own wounded limb,
brought it down in his hand to the kitchen, and. gently placed
the servant-boy’s foot upon it*,

cc The

* Somewhat similar to the above anecdote, is the following very pleasing fact,
eommunicated to Mr Guennte by Huen Irvine, Esq; (son of Mr Irvine of
Drum). I give it in Mr Irvine’s own words.

6 Mr Lesute of Darkland, a clergyman, called one day, and was taken by Miss

Mrrcuett to see something out of doors. When they returned, James Mrr-
cuELL perceived (no doubt by the sense of smell) that his. sister’s shoes were
wet: he then went and felt them, and would not let her rest till she changed
them,”

BORN BLIND AND DEAF. 29

“ The last time I saw young Mircuetr, was on the melan-
choly occasion of his father’s funeral, in the month of June
last. According to Mr Guienniz’s communication, it would
seem, that the boy, even before his father’s interment, had ex-
pressed by sorrow and bemoaning, a knowledge of the irrepa-
rable loss he had sustained. On this point, the deep distress
under which the family then laboured, prevented me from ma-
king any inquiries. But the poor lad’s behaviour on the day
of the funeral, seemed to me so little expressive of grief, that
I cannot help doubting in some degree the accuracy of Mr
GLEnniz’s information. It will be regarded as a pleasing tes-
timony of the sincere esteem in which Mr Mircuent was held
for his moral worth and exemplary piety, that several hundreds
of his friends and parishioners assembled together, to carry his
remains to the grave. While this concourse of people waited
the commencement of the procession in front of the manse,
young MircueE.t at one time moved rapidly among the crowd,
touching almost every body, and examining some very mi-
nutely ; at another time, he amused himself opening and shut--
ting the doors, or turning down. and up the steps of the carri-~
ages; or suddenly. he would walk towards the coffin, which
was placed on chairs before the door of the house, run his fin-
gers along it with marks even of pleasure, and then trip light-
ly away, without the slightest expression. of sorrow. Epi ac-
companied the procession, to the church-yard, and returned af-
ter the interment, apparently. as much unmoved as before.
But on the following morning, as I have since been informed,
and on several mornings see he visited the grave, pat~
ted gently the, turf. which. had. been laid over it, and at last, as

if

30 ACCOUNT OF A BOY

if hopeless of his father’s return, became sorrowful even to
tears'*=

THE

* Soon after this memoir was read, I informed Mr Guewnre of the difference
‘in the accounts given by Mr Macrartane and by Dr Gorpon, of young Mit-
cnext’s behaviour on the day of his father’s funeral. In a Jetter with which he
has lately favoured me (dated May 10. 1812,) there is a passage transcribed
from a letter of Mr Macrartanx’s (dated May 7.) which I think it proper to
subjoin to the foregoing details, as an important document with respect to this.
interesting point ;—the only point of any consequence in which the two papers
do not perfectly agree.

‘* In the account which I transmitted to you of James Mircney, I mentioned.
that he seemed much afflicted and very sorrowful the day of his father’s funeral 5.
and I now beg leave explicitly and. positively to state, that when the coffin
which enclosed his father’s corpse was brought from the house, and placed upon
chairs in the court before the manse, previous to the interment, I approached to
the coffin, and soon after saw James Mircuext come from the house in consi-
derable agitation. He turned about his head rapidly, and snuffed very much,
evidently guiding himself by the sense of smell. He directly approached the cof-
fin, smelled it most eagerly for several seconds; then Jaid himself down upon
the lid, on his face, and embraced the coffin, while his countenance discovered
marks of the most lively sorrow. I stood close by him, and after a short time,
patted his head once or twice ; upon which he rose, and returned into the house.
This occurred immediately upon the coffin being brought out, and about twenty
minutes before it was lifted, in order to be-.carried to the church-yard. As the
accuracy of my information on this subject has been doubted, I purposely delay-
ed writing to you, till I should have an opportunity of conversing with the Re- -
verend Pryse Campsexx, minister of Ardersier, brother-in-law to Mrs Mir-
CHELL, who was present at the funeral, and by whose direction every thing was
conducted. I fell in with this gentleman on Tuesday se’ennight, at the meeting
of our Provincial Synod. I took an opportunity there of asking him, if he ob-
served any marks of sorrow about James Mircnext on the day of his father’s
funeral. He replied, that he did observe the most unequivocal marks of grief
in his countenance ; and added a circumstance which escaped my notice, that

when

BORN BLIND AND DEA? $1

Tur case described in the foregoing’ papers is said by Mr
Warprop, in a letter of his already quoted, to be unique, to the
best of his knowledge ; and that it really is so, I am inclined to
believe, as far as this can be inferred from the silence of scienti-
fic writers *. That it is, at least, a very rare occurrence, 1s de-

monstrated

when the coffin was about to be lifted, in order to be carried to the church-yard,
James Mitcaext clung to it, endeavouring to prevent its being carried away,
and that he (Mr Campzext) was obliged to remove him from it by force.”

After quoting the above passage, Mr Guennie adds :-—‘‘ Mr Macraruaye,
in his remarks on the apparent inconsistence between Dr Gornon’s account of
young Mrrcueut and his own, has expressed what occurred to me immediately
after I read your last letter. His words are: ‘“‘ I would observe, that the cir-
cumstances mentioned by Dr Gorpon, of Mircueti’s running through the
crowd, and touching every person, do not, in my opinion, amount to a proof,
that he was insensible of the loss which he had sustained, and felt no grief on
that account. In acting thus, Mircueuu (if the expression may be allowed) was
merely viewing the assemblage of people around him. This he could not do by
his eyes; but being eager to examine them, he did so by means of the senses of
which he has the use. In short, he was grieved ; but, in this instance, his curio-
sity overcame his grief.” The remark certainly does honour to Mr Macrar-
LANE’s sagatity, and, in my opinion, goes far to reconcile the two narratives. I
hope to be able soon, through Dr Gorpon’s means, who proposes to pass a part
of this summer in that neighbourhood, to obtain from the mother and sister of
the young man, a stil] more circumstantial account of his general behaviour, and
of the apparent state of his feelings at this trying crisis of his life. Some very
interesting particulars, with respect to these points, (which have been already
communicated to me by this gentleman) may be found in an Appendix annexed
to this memoir. (May 20. 1812.)

* In Diveror’s very ingenious and fanciful Letter on the Blind, there are va-
rious allusions to the hypothetical case of an Aveugle-Sourd-Muet. In one pas-
sage,

32 ACCOUNT OF A BOY

monstrated by a passage in the Abbé Sicarp’s Course of In-
struction for the Deaf and Dumb, where it is mentioned only
as a hypothetical contingency, which had been contemplated
by him and by his predecessor the Abbé de l’Epr’g, as a pos-

sible,

sage, he remarks, somewhat whimsically, that if a person born in these circum-
stances, should begin to philosophize concerning man, according to the method
of Descartes, he would place the seat of the soul at the tips of his fingers ; and,
in all probability, after an effort of profound meditation, would feel his fingers
ache as much as we should do our heads. From the following sentence, one
would be led to suppose, that Dineror had actually seen or heard of persons in
the same condition with Mrrcue.x; but if this really had been the fact, we may
presume with some confidence, that he would not have contented himself with so
vague and equivocal a reference to an occurrence at once so anomalous and so
curious in the physical history of man. “ Faute Pune langue, la communication
« est entiérement rompue entre nous et ceux gut natssent sourds, aveugles, et muets :
“ als croissent, mats ils restent dans un etat @imbecillité.”

In those valleys of the Alps, indeed, where the disease of Crétinisme is com-
mon, examples are said frequently to occur of an almost total deprivation of all
the senses ; but, in such instances, the individual presents invariably, in the low
and humiliating state of his intellectual capacity, a very striking contrast to the
subject of this memoir. The universal torpor in the perceptive faculties of the
Crétin, is plainly an effect of the same radical disorder which impairs his intel.
lect; whereas, in the instance before us, (as in every instance where the intel-
lect is entire), the mind, checked and confined in the exercise of one class of
her powers, displays her native strength by the concentrated energy which she
exhibits in others. The following description relates to an extreme case of Crétt-
nisme ; for it appears, that it admits of various gradations. It is taken from
the most circumstantial, and apparently the most accurate, account of this local
malady that has fallen in my way.

“© The sensibility of the Crétzn is extremely obtuse: he dreads neither cold
nor heat, nor vermin; nor even those blows which would be insupportable to
another.

«« The greater part are evidently deaf and dumb; although I have happened
to see a few who would shudder at the report of a pistol. These last would
seem to receive some passive impression from sound; but they are certainly in-

capable

BORN BLIND AND DEAF. 133

- sible, and not altogether as an improbable event, among the
- various physical’ calamities to which our species is liable. > It.
_appears from the same. ingenious author, that the Abbé de
/)Eprrr had even gone so far, a few years before his death, as
to offer, in some of the Continental Journals, with his charac-
teristical benevolence, to undertake the charge and tuition of
any child who might:be brought into the world in. these unfor-
-tunate circumstances; and M. Srcarp has not only taken the
trouble to record the general principle on which the Abbé de
_TErrr intended, if this accident should cccur, to have pro-
ceeded in the education of his pupil; but has added some very
_judicious strictures of his own, on the imperfections of the plan
which his predecessor proposed, in such an instance, to follow.
These

_ eapable of listening to what is passing around them. The organ of Smell is in-
sensible; and the power of Taste but imperfectly developed. The sense of see-
ing alone appears uninjured by the disorder; but even from this. they derive little
benefit. They gaze with ipacigecn Gy on the fe a of Nature; and if they

- gee, can hardly be said to perceive.” . . . ice et! Sah acet et i boas ae

“« This disease is peculiar to the braced species. All the classes of animals,
from the oyster to the monkey, possess a sufficient degree of intelligence, to pro-
cure the means of their own subsistence. The Créiin, on the other hand,
would die of hunger, if his wants were not provided for by the attentions of

~ others.”

(Tratté du Gottre et du Crétinisme, par F. FE. Foderé, Ancicn Médecin des Ho-
pitaux civils et militaires. A Parts, an vin.)

Since this note was written, I have received a letter from Mr Giennin, in
which he remarks, and, in my opinion, very justly, that the case of Mrr-
cHELL is probably not so very rare an occurrence, as we might, at first, be dispo-
sed to imagine. “ Among the various merits (he observes) of this worthy fami-
ly, their superiority to such prejudices as would have precluded our getting any
information about the lad’s state of mind, is deserving of peculiar notice. . .. .
I have reason to believe, that there are others in circumstances similar to young

_MrrcueEtu’s, whose cases are, at this day, kept so secret, that they are not so
much as known to the inmates and members of the family to whom they belong,”

Vou, VII. E

S34 - ACCOUNT OF A BOY

These strictures I cannot help taking this opportunity of re-
commending to the attention of those who may attempt the far-
ther instruction of young Mircurtt. The following abridged
translation * of a passage in the preface, may, in the mean
time, suggest some useful hints.

ribet Seay ni But, if there should be found a person deaf and
dumb, in whose case the use of this visible language was imprac-
ticable; if, among the afflicting exceptions and mutilations of
nature, an individual should occur, deaf and blind from his birth,
to what class of signs should we have recourse in attempting his
“education ? At what an immense: distance from other men
would a being so cruelly degraded be placed ; and how difficult
to transport him across that gulf by which he is separated
from the rest of his species? ‘The means of instruction em-
ployed in ordinary instances of dumbness, would here be ma-
nifestly inapplicable ; all of these means presupposing the use
of sight, to which a constant reference is made, not only in the
communication of physical ideas, but in typifying the processes
of thought, and in rousing the dormant powers of the under-
standing.

“ T flatter myself, I have already proved, that, from the be-
ginning, Man possessed, in his own bodily organs, two differ-
ent media for conveying his ideas; and that, instead of em-
ploying oral speech, he might have had recourse to a manual
language. Why, then, might we not, in the supposed case of

a

* In this translation, I have not only omitted several sentences in the
original, which did not appear to bear upon my present object, but have not
scrupled to interpolate a few clauses of my own, which I thought might be use-
ful in conveying the author’s meaning more clearly to an English reader. The
sense of the passage is rendered, to the best of my judgment, with perfect fide-
lity.

BORN BLIND AND DEAF. 35

‘a blind and deaf pupil, avail ourselves of the assistance of the
latter, which, if not visible to his eye, would be, at least, tan-
gible to his hand. It is only extending farther the use of a
species of signs already practised between Massizu and me,
when, dussioas) the darkness of night, he sees by his own hands
whatever mine would express to him. Why should not the
blind and deaf pupil be taught to converse in the same man-
ner, during the light of day ?

“ Ah! if the experiment I should wish to make were to
prove not altogether useless; if, as, I have already done for the
deaf and dumb, I should be. the! instrument, of, bestowing a
mind on this still more unfortunate object, I should myself en-
joy a degree of happiness greater than any which he could pos-
sibly derive from, the success of my labours!

“ My illustrious predecessor had the boldness to. think, that
even this case, if it) should be realised, would not present, un-
ssurmountable obstacles to an instructor. The following is an
outline of the plan upon which, he told me, it was his inten-
tion. to proceed. .

“ An alphabet of polished steel was to be employed as the
materials of his nomenclature for sensible objects, and for those
actions which might be brought under the cognizance of the
sense of Touch. He hoped to be able to familiarise his pupil
with these characters, so as to devolve upon his hands the of-
fice of his eyes; and, for this purpose, he proposed to make
him feel the object. with one hand, while he was learning to
distinguish its name with the other. His inventive genius
would doubtless have led him, in the course of his experi-
ments, to whatever other means were necessary for the attain-
ment of his end.

_“ Tam perfectly aware, that difficulties would immediately
present themselves at every step ; for, how would it be possi-
je 7 ble,

36° “ACCOUNT OF A BOY

ble, without any intercourse either by the eye or by the ear,
to’establish, in the pupil’s mind, the connection between the
object and its sign? I apprehend, it would be necessary here
to avail ourselves of some of his animal instincts ; to withhold,
for example, the objects of his desires and wants, till he should
recollect their names, and exhibit their characters *. This
first step would perhaps be followed by a second; that of
teaching him to distinguish the qualities and modes of ob-
jects. Colours and sounds would, of course, be excluded
from our lessons ; but the forms of bodies, which fall under the
province of Touch, might be easily impressed on his memo-
ry; and upon this basis, what should prevent us from proceed-
ing to rear a metaphysical structure? If those qualities which
strike the sense of Sight have gradually led the deaf and dumb
to the knowledge of things intellectual and moral, why should
not the qualities about which the sense of Touch is conversant,
be made the channel. to the same sort-f information? In-
stead of speaking to the eye, we have only to speak to the
hand. In truth, the whole system of instruction explained in
the following work, might be adapted to our new pupil, by
presenting to him, in’ relievo, the various delineations and dia-
grams by’ Lisa it is PA phe those pa changes being

‘ made

* In the case of Mitcuext, the difficulties here alluded to would probably be
experienced in a comparatively small degree, in consequence of the previous use
of those significant pressures on his forehead, of which his sister has taught him
to comprehend the meaning. If this should turn out to be the fact, she has al-
ready got. over, by her own ingenuity, the first and most arduous step in the
whole process of his education.

Mr Warpror takes notice, in one of his communications, of his extreme do-
cility, and of his obedience to the commands of his sister, who, during his stay
in London, ‘¢ was his constant companion and guide.” ‘ It was astonishing
(he adds) how readily she could communicate to him, by signs, her wishes.”

BORN BLIND AND DEAF. : Se.

made in the method, which the circumstances of the case
would readily suggest. his pupil, (as has often happened in
the education of the deaf and dumb), would soon become the
“master of his teacher; and every step which was gained, would
of itself, point out the next which was to be taken *.

“ May such a system of instruction remain always matter of
pure speculation! Gop forbid, that a child should ever be brought
into the world, without any substitute but the hand for the eye
and for the ear! But as, unfortunately, such a deviation of nature
from her usual course, is an event but too possible, let us con-
sider beforehand what may be done, by way of remedy or of
alleviation. To restore a Man to society, to his family, and to
himself, would be an enjoyment too exquisite, and a conquest
too proud, to permit us to abandon the undertaking in de-
spair.”

For a comment on the above observations, I must refer to
the work at large. They who read it with attention, and who
enter fully into the author’s views, will be at no loss to per-
ceive the different modifications which his plan will require,

sua

* It is somewhat surprising, that the Abbé Srcarp should have overlooked
the aid which the sense of Smelling seems so peculiarly calculated to furnish, for
rearing his proposed Metaphysical Structure. Some of the most significant words
relating to the Human Mind, (the word sagacity, for instance), are borrowed
from this very sense; and the conspicuous place which its sensations occupy in
the poetical language of all nations, shew how easily and naturally they ally
themselves with the refined operations of the Fancy, and with the moral emo-
tions of the Heart. The infinite variety of modifications, besides, of which they
are susceptible, might furnish useful resources, in the way of association, for
prompting the memory, where it stood in need of assistance.

One of the best schools for the education of such a pupil, would probably be a
well-arranged Botanical Garden.

38 ACCOUNT OF A BOY.

in applying it to. such a case as that of Mircnerx. His fun-
damental principles are general, and deeply philosophical ;
being, all of them, deduced from a careful study of the steps
by which children gradually and insensibly acquire the use of
oral speech ; and of consequence, they are equally applicable
to every species of signs by which one mind can hold inter-
course with another. In the mean time, I beg leave to add
to the foregoing quotation, the account given by Sicarp of his
first lesson to Massizu, as it touches on a very natural mistake,
which, with a few, if any exceptions, has misled all those who
have hitherto undertaken the education of the deaf and dumb ;
and which, in case any attempt should be made for the farther
improvement of Mircuenz, it may be worth while to point
out, by way of caution, to his instructors.

“« My first lesson was employed upon the alphabet. I had
not yet reflected on the imperfection of this method, which,
from the first outset, counteracted that analytical procedure
which is natural to the mind, and by which alone the mind can
be guided to the use of its faculties. What information, in
reality, (as I afterwards began to question myself), can the un-
derstanding possibly derive from a series of abstract characters,
arranged in a particular order by chance or caprice, and to which
nothing equivalent can be exhibited in Nature? But it was
thus that my illustrious Master began, and every step in his
system seemed to me then indispensable and sacred.”

In a subsequent passage, M. Sicarp takes notice still more
explicitly, of the absurdity of teaching a pupil in such circum-
stances to read or to copy isolated letters, in that order which
our alphabet exhibits. ‘“ What interest, (he asks), could Mas-
sizu have felt about characters signifying nothing, and occupy-
ing, without any conceivable reason, a certain place in an arbi-
trary series? Accordingly, I directed his attention at once to

words,

BORN BLIND AND DEAF. 39

words, without attempting to explain to him that the elements
of these words were letters, and still less that these letters were
consonants and vowels. Indeed, how was it possible for him
to annex any notion to the technical terms of grammar, when
-he was not yet in possession of a language, and when he had
only a few fugitive notions to fix and to express ?”

In these extracts, M. Sicarp describes, with great candour,
the process of thought by which he was conducted to (what I
consider as by far the most important of the many improve-
ments which he has introduced into his art) the simple, yet
luminous idea, of copying his plan of instruction, not from
the example of a schoolmaster teaching a child to read, but
from the example of the child itself, in acquiring the use of its
mother-tongue. Of these two methods, the former, it must be
owned, is by far the more obvious; and where mere articula-
tion is the chief object of the teacher, it will probably be found
the more easy and effectual in practice. But Sicarp’s aim was
of a different, and of a higher nature ;—not to astonish the
vulgar by the sudden conversion of a dumb child into a speak-
ing automaton ; but, by affording scope to those means which
Nature herself has provided for the gradual evolution of our
intellectual powers, to convert his pupil into a rational and
moral being. The details of his lessons, accordingly, are not
more interesting to the few, who may attempt the education of
such unfortunate ewceptions as Massieu or Mrrcueny, than to.
all those who delight in tracing to their elementary principles
the materials of human knowledge, and in marking the first
openings of the infant mind *. |

In

* See the Note at the end of the Memoir.

40 ACCOUNT OF A BOY

In order to complete the history of Mrrcurtr, I am aware
that a variety of curious points still remain to be ascertained ;
and, if I had not been anxious to bring it forward to public no-
tice, even in its present imperfect state, without any farther
delay, I should have been inclined to retain it in my own
hands, till my information on the subject should have been a
little more ample. My wish, I must acknowledge, is, That
some plan could be devised for removing the young man to
Edinburgh ; or rather (as he has been accustomed hitherto to
enjoy the air and the freedom of the country), to some quiet
residence in the neighbourhood ;—to some situation, in short,
where an opportunity would be afforded for examining and re-
cording, under the eye of this Society, the particulars of a case,
to which it is to be hoped, that nothing similar will again-oc-
cur in our times. Something, it would appear from Dr Gor-
pon’s statement, may perhaps, at a future period, be attempted
for the extraction of his cataracts,—in which event (should
the operation succeed), I need not say, what an accession
would at once be made to his own enjoyments, and to his va-
lue as an object of philosophical curiosity :—But even on the
supposition that this hope should be disappointed, a subject of
_ inquiry not less interesting than any question connected with
the Theory of Vision, will still remain,—to ascertain how far it
might be possible, by following out the Abbé Sicarp’s hints,
to cultivate the intellectual and moral faculties of a human be-
ing, destitute of the two senses which are the ordinary vehicles
of all our acquired knowledge. Nor do I apprehend that this
experiment would be attended with such insuperable difficul-

ties

BORN BLIND AND DEAF. 4]

ties as might at first be suspected ; as I am assured by the best
authority, that his eldest sister, whose good sense has already
devised some imperfect modes of communication with her un-
fortunate brother, possesses talents which fully qualify her to
carry into execution any plan that may be proposed for his
farther improvement. His age, at present, only exceeds by
two years, that of Sicarn’s celebrated pupil Massrev, when his
education was begun ; and at that period, Massiev, though he
had the inestimable advantage of possessing the sense of Sight,
seems to have had his rational faculties as imperfectly develo-
ped as those of Mircne.t.

I must, at the same time, observe here, in justice to myself,
that my expectations of the future improvement of the latter,
are by no means so sanguine as those which the Abbé Sicarp
would probably have indulged in similar circumstances. Were
it possible, indeed, to place him under the immediate tuition
of that eminent man, I have little doubt that much more would
be accomplished than: appears to us to be practicable ; but the
difference between his ‘situation and that of Massirv is so im-
mense, as to render all our conclusions founded on the history
of the one, quite inapplicable (except with great modifications)
to the case of the other. . The slowness with which the sense of
Touch proceeds, in collecting information concerning the exter-
nal world, when compared with the rapid perceptions of the Eye,
would, on the most favourable supposition, retard infinitely the
rate of his progress:in acquiring even the first elements of know-
ledge. This, however, furnishes no argument against the attempt;
nor does,it even tend to diminish the value of the results to which.
it might lead. The slightest addition that could be made to.
his present range of ideas, bby means | OF an improved system of

aod Nia insonh cy | signs.s

42 ACCOUNT OF a’ BOY”

signs ; and still more, the slightest developement that could be:
given to any of his dormant powers, might afford not less im--
portant data for philosophical speculation than the most ex-
tensive acquisitions. .

Havrne mentioned more than once the name of Massrev,.
I think it proper to subjoin to the preceding remarks, the de-
scription of him given by Srcarp, at the time when their ac-.
quaintance commenced. It may serve to shew, that the idea.
of attempting the education of Mrrcwetn, even at the age of
sixteen, is not altogether chimerical. .

“ The reader will easily form an idea of the character and
manners of Massirzv, when he is told, that he was born in a
cottage, six leagues from Bordeaux; and that his relations.
(who were the only individuals with whom he ever had any
intercourse) had not even taken the trouble to communicate to
him the slightest information about material objects. His child-
hood had been spent in tending a flock ; and all his ideas were
confined within the narrow circle which had fallen under his.
random observation. Massrtev was a Man of the Woods; untine-

tured with any habits but such as were purely animal; astonished.

and terrified at every thing. In coming to Bedddmees he had
believed that he was only changing his place of abode; and
that he would be employed there in keeping another flock :
but it was towards the beloved scene which he had left, and
which had witnessed the first sports of his infancy, that his
imagination was incessantly turned. In every thing he saw,
he apprehended some danger; in every step he was directed
to take, he suspected some snare. How far was this simple
boy, accustomed as he was to consider himself on a level with.
the animals entrusted to -his care, from dreaming that he was
about to be raised by education to the rank of Man! His
clouded

BORN BLIND AND DEAF. 43

clouded: and inexpressive countenance ; his doubtful and shift-
ing eye ; his silly and suspicious air,—all seemed to announce,
that Massizv was incapable of any instruction. But it was not
Jong till he began to inspire his ‘Teacher with the most flatter-

ing hopes.”

Abstracting, however, entirely from all conjectural. specula-
tions with respect to MircuEx1’s possible attainments in future,
the particulars already in our possession afford data for some
important conclusions concerning the capacities of the Human
Mind, considered in contrast with the instincts of the Brutes.
For these I do not think that the Transactions of this Society
afford a proper place ; and I have accordingly, all along, confi-
ned myself to the detail of facts, leaving the philosophical
inferences to which they may lead for future consideration.

_ Nor is it, in this point of view. alone, that his case is an ob-
ject of curiosity at the present-moment. ‘The examination of his
powers of external perception (considered merely as articles of
natural history *) promise, under the peculiar circumstances of

0 vous bijneaicgay, 2 his

* I cannot help quoting here .a very curious observation of Mr Warprop’s,
with wespect to the partialities and dislikes conceived by Mircue.s, in conse-
quence of the moral expression, (if I maybe allowed such a phrase), which he
seems to have attached to particular sensations of smell. «‘ When a stranger(says
he) approached him, he eagerly began to touch some part.of his body, common-
ly taking hold of his arm, which he held near his nose; and after two or three
strong inspirations through his nostrils, appeared decided in his opinion. If it
happened to be unfavourable, he suddenly went to a distance with the appear-

_ance of disgust ; if favourable, he shewed a disposition to become more intimate,
and expressed, by his countenance, more or less satisfaction.”

44 ACCOUNT OF A BOY

liis condition,.a field of study, of which, if it has ever occurred
before in the annals of our species, no scientific use appears to
have been made. How much the simultaneous exercise of our
different senses obstructs the perfection of each, may be infer-
red from the delicate touch, and acute hearing of the blind.
It remains to be ascertained, to what degrees of improvement,
the perceptions of Feeling, of Taste, and of Smell, may attain
in an individual possessed of these senses alone *. esti)

I

* In one of the communications which I have received, it is said, that ** Mitr-
cHELt has been known to follow the footsteps of another person for two miles,
guided merely by the sense of smelling.” As this circumstance, however, is sta-
ted only on report, I have not introduced it into the text; and mention it here
chiefly in the hope of obtaining more precise and authentic information upon the

subject.

It would be desirable also to learn something more circumstantial and speci-
fic, both with respect to the discriminating powers of his palate, and his predi-
lections in the article of food.

Neque inutile foret, neque ab honestissima sapientia alienum, novisse quo-
modo hic miserandus, jam puber factus, se habuerit quod ad res venereas ; hunc
appetitum an senserit necne; qua forma, quibus indiciis se prodiderit ; foemina-
rum an virorum consortio adolescenti magis placeat; socii sexum an olfactu dig-
noscere videatur. Hec et similia bene multa, dictu parum decora, scitu vero
non indigna, si mod6 observandi copia data fuerit, unicuique in mentem venient
cui Natures Humane scientia est cordi, quique infelicissimum et pené singularem
illius statum rité contemplabitur.

BORN BLIND AND DEAF. 45

I shall only add farther, before concluding this memoir, that,
in submitting it to the Royal Society, I was partly influenced
by the hope, that it may possibly be the means of securing a
decent provision for the individual to whom it relates ;—per-
haps, also, a competent independence for those members of his
family on whom he has been so long a burdensome and expen-
sive charge. I allude, not merely to his mother, whose claims
must immediately force themselves on the notice of every one,
but more particularly to his eldest sister, on whom the duties’
of superintending and educating him have chiefly devolved
from his infancy. ‘To the painful and incessant attentions.
which his helpless condition required, the best years of her lite
have been hitherto devoted ; and so essential is the continua-
tion of the same affectionate cares to his comfortable existence,
that, independently of what is due to her own singular merits,
she must, of necessity, be included in any arrangement, of
which his improvement and happiness are the principal ob-
jects. For the purposes already mentioned in this paper, the
funds of the Society, I am well aware, are altogether inade-
quate ; but if they shall be pleased to recommend the business
to the consideration of their Council, I have no doubt, that
something may be suggested for the accomplishment of a mea-
sure, which, even if it should fail in adding materially to the
stock of useful knowledge, would at least prevent the regrets
which might afterwards be felt, if so rare an opportunity for
philosophical observation and experiment should be suffered
to pass before our eyes, without any attempt being made to
turn it to the advantage of science.

NOTE,

46 ACCOUNT OF A Roy

NOTE, p. 39.

I wave been led to insist at some length on the philosophi-
cal merits of Sicarp’s plan of instruction for the Dumb, not
only because his fundamental principles admit of an obvious
application (mutatis mutandis) to the case of Mrrcuettz ; but be-
cause his book does not seem to have attracted so wisn notice
in this country as might have been expected, among those who
have devoted themselves to the same profession. Of this no
stronger proof can be produced, than the stress which has been
laid by most of our Teachers, on the power of articulation,
which can rarely, if ever, repay, to a person born deaf, the time
and pains necessary for the acquisition. This error was, no
doubt, owing, in the first instance, to a very natural, though
very gross mistake, which confounds the gift of Speech with the
gift of Reason ; but I believe it has been prolonged and con-
firmed in England, not a little, by the common union of this
branch of trade with the more lucrative one, of professing to
cure organical impediments. To teach the dumb to speak, be-
sides, (although, in fact, entitled to rank only a little higher
than the art of training starlings and parrots), will always ap-
pear to the multitude, a far more wonderful feat of ingenuity,
than to unfold silently the latent capacities of the understand-
ing ;—an effect which is not, like the other, palpable to sense,
ane of which but a few are able either to ascertain the exist-
ence, or to appreciate the value. It is not surprising, there- —
fore, that even those Teachers who are perfectly aware of the
truth of what I have now stated, should persevere in the diffi-
cult, but comparatively useless. attempt, of imparting to their

pupils.

BORN BLIND AND DEAr. 47

pupils that species of accomplishment, which is to furnish the
only scale upon which the success of their own labours is ever
likely to be measured by the public.

The example of Dr Wauus of Oxford, the most eminent
English author who has yet turned his attention to this study,
has jgrobalely had considerable influence in misleading his suc-
cessors. His thoughts (as he tells us himself), were Maiaiballe
led to it by his analytical inquiries concerning the mechanical
formation of articulate sounds, a subject which he appears to have
very deeply and successfully meditated ; and accordingly, the
first step which he took with his two most distinguished pupils
(Pornam and Wuazey) was to teach them to speak. He also
informs us, that he had in various instances applied the same
principles, in curing organical impediments. Indeed, it was
evidently on this branch of his art, that he valued himself
chiefly as an instructor of the dumb. In cultivating the intellec-
tual powers of these, his success does not seem to have been
such as to admit of comparison with that of the Abbé Sicarp;.
and it is remarkable, that the pupils, of whose progress he
speaks most highly, are a few with whom he carried on all his
intercourse by means of writing, without wasting any of their
time in communicating to them the gift of oral speech. “ A-
* lios aliquot surdos, loquelam docere non agressus sum, sed
*« solummodo ut res scriptas mediocriter intelligerent, suaque
*¢ sensa scripto quadantenus insinuarent : Qui tempore non lon-
“ go progressus eos fecerint, rerumque plurimarum notitiam ac-
“ quisiverint, multo ultra quam quod putabatur fieri posse a quo-
* quam in eorum circumstantiis posito; fuerintque plane capaces
acquirendi (si pee exculti) ultiorem cognitionem que pos-
“ sit scripto impertiri.” See Watuisu Opera Mathemat. vol. iii.
p: 696. See also his letter to Mr Brvertey, in the Transac-
tions of the Royal Society of London for 1698.—I am obliged

to

48 ACCOUNT OF A BOY.

to quote from the Latin version, not having the Philosophical
‘Transactions at hand.

After having thus paid the tribute of my sincere respect to
the enlightened and benevolent exertions of a celebrated fo-
‘reigner, I feel myself called on to lay hold of the only oppor-
tunity that may occur to me, of rescuing from oblivion the
name of a Scottish writer, whose merits have been strange-
ly overlooked both by his contemporaries and by his suc-
cessors. The person I allude to is Gzorce Datearno, who,
more than a hundred and thirty years ago, was led by
his own sagacity, to adopt, @ priori, the same general conclu-
sion concerning the education of the dumb, of which the expe-
rimental discovery, and the happy application, have, in our
times, reflected such merited lustre on the name of Srcarp.
TI mentioned Datcarno formerly, in a note annexed to the Phi-
losophy of the Human Mind, as the author of a very ingenious
tract entitled Ars Signorum, from which it appears indisputably
that he was the precursor of Bishop Wizx1ns in his specula-
tions concerning a Real Character, and a Philosophical Lan-
guage ; and it now appears to me equally clear, upon a farther
acquaintance with the short fragments which he has left be-
hind him, that, if he did not lead the way to the attempt
made by Dr Watts to teach the dumb to speak, he had
conceived views with respect to the means of instructing them,
far more ‘profound and comprehensive than any we meet
with in the works of that learned writer, prior to the date
of Datearno’s publications. On his ‘claims in these two
instances I forbear to enlarge at present; but I cannot deny
myself the satisfaction of transcribing a few ‘paragraphs,
in justification of what I have already stated, with respect to
the remarkable coincidence between some of his theoretical
deductions,

BORN BLIND AND DEAF. 49

deductions, and the practical results of the French academi-
cian.
“ I conceive there might be successful addresses made to a
dumb child even in its cradle, when he begins—risu cognoscere
- matrem; if the mother or nurse had but as nimble a hand, as
commonly they have a tongue. For instance, I doubt not but
the words, hand, foot, dog, cat, hat, &c. written fair, and as of-
ten presented to the deaf child’s eye, pointing from the words
to the things, and vice versa, as the blind child hears them spo-
ken, would be known and remembered as soon by the one as

the other. And as I think the eye to be as docile as the ear ;
so neither see I any reason, but the hand might be made as

- tractable an organ as the tongue ; and as soon brought to form,
if not fair, at least legible characters, as the tongue to imitate
and echovback articulate%sounds?*") 2.) vO.
“ The difficulties of learning to read, on the common plan, are
so great, that one may justly wonder how young ones come to
get over them. ..... Now, the deaf child, under his mother’s
tuition, passes securely by all these rocks and quicksands. The
distinction of letters, their names, their powers, their order,
the dividing words into syllables, and of them again making
words, to which may be added Tone and Accent; none of
these puzzling niceties hinder his progress....... It is true,
after he has past the discipline of the nursery, and comes to
learn grammatically, then he must begin to learn to know let-
ters written, by their figure, number, and order, &c. &c.

The same author elsewhere observes, that “ the soul can ex-
ert her powers, by the ministry of any of the senses: And, there-
fore, when she is deprived of her principal Secretaries the Eye
and the Ear; then she must be contented with the service of her
lackeys and scullions, the other senses; which are no less true
and faithful.to their mistress, than the eye and the ear ; but not so
quick for dispatch.”

Vou. VIL G. |

50 ACCOUNT OF A BOY

I shall only add one other sentence, from which my readers
will be enabled, without any comment of mine, to perceive
with what sagacity and success, this very original thinker, had
anticipated some of the most refined experimental. conclusions
of a more enlightened age. .

“ My design is not to give a methodical system of gramma-
tical rules ; but only such general directions, whereby an indus-
trious Tutor may bring his deaf Pupil to the vulgar use and
ov: Of a language ; that so he may be the more capable of re-
ceiving instruction in the 0% ov from the rules of grammar,
when his judgment is ripe for that study : Or, more plainly ; I
intend to bring the way of teaching a deaf man to read and
write, as near as possible, to that of teaching young ones to
speak and understand their mother-tongue.”

In prosecution of this general idea, he has treated, in one
very short chapter, of a Deaf Man’s Dictionary ; and in ano-
ther, of @ Grammar for Deaf Persons ; both of them contain-
ing (under the disadvantages of a style uncommonly pedantic
and quaint) a variety of precious hints, from which, if I do not
deceive myself, useful practical lights might be derived, not
only by such as may undertake the instruction of such pupils
as Mrrcuery or Massievu, but by all who have any concern in
the tuition of children during the first stage of their educa-
tion.

The work from which these quotations are taken, is a very
small volume, entitled “ Didascalocophus, or, The Deaf and
“ Dumb Man’s Tutor, printed at the Theater in Oxford, 1680.”
As I had never happened to see the slightest reference made
to. it by any subsequent writer, I was altogether ignorant of its
existence, when a copy of it, purchased upon a London stall,
was a few years ago sent to me by a friend, who, amidst a mul-
tiplicity of more pressing engagements and pursuits, has soa

OS

BORN BLIND AND DEAP. 3i

lost sight of the philosophical studies of his early years. I
have been able to learn nothing of the author, but what is
contained in the following slight notice, which I transcribe
from Antuony Woop. “ The reader may be pleased to know,
that one Grorce Datcarno, a Scot, wrote a book, entitled, Ars
Signorum, &c. London, 1660. This book, before it went to
press, the author communicated to Dr Wixkins, who from
thence taking a hint of greater matter, carried it on, and brought
it up to that which you see extant. This Datcarno was born
at Old Aberdeen, and bred in the University at New Aber-
deen ; taught a private grammar school with good success for
about thirty years together, in the parishes of S. Michael and
S. Mary Mag. in Oxford ; wrote also, Didascalocophus, or, the
Deaf and Dumb Man’s Tutor; and dying of a fever, on the
28th of August 1687, aged sixty or more, was buried in the
north body of the church of S. Mary Magdalen.” (Ath. Oxon.
~ vol. il. p. 506-7.)

The obscurity in which Danearno lived, and the complete
oblivion into which his name has fallen, are not a little won=
derful, when we consider that he mentions among the number
of his friends Dr Sera Warp, Bishop of Sarum ; Dr Jonn Wit-
Kins, Bishop of Chester ; and Dr Joan Watts, Professor of
Astronomy at Oxford. It is still more wonderful, that no no-
tice of him is taken in the works either of Wixxiys or of Wat-
L1s, both of whom must have derived some very important aids
from his speculations.

This ‘unfairness on the part of Wiixins, has not escaped the
animadversion of one of his own biographers. “In the prefa-
tory epistle (he observes) to the Essay towards a Real Charac-
ter, Dr Witxrns mentions several persons who assisted him in
this work, particularly Wittovessy, Ray, and Dr WituaM
Luoyp and others ; but it is remarkable, that he does not men-

G2 tion

§2 - ACCOUNT OF A BOY

tion DatcarNno, and the more, because Dr Wiikins’s own
name is printed in the margin of King Cuaruzs II.’s letter pre-
fixed to Datcarno’s book, as one of those who informed his
Majesty of Dalgarno’s design, and approved it, as a thing that
might be of singular use to facilitate an intercourse between
people of different languages ; which prevailed with his Majes-
ty to grant his said letters of recommendation to so many, of
his subjects, especially of the Clergy, as were sensible of the
defectuousness of art in this particular.” Biog. Britan., Art.
Witxins *..

That Datcarno’s suggestions with respect to the Education
of the Dumb, were not altogether useless to Dr Watts, will,
I think, be readily admitted by those who take the trouble to
compare his letter to Mr Bevery (published eighteen years
after Datearno’s treatise) with his Tractatus de Loquela, pu-
blished in 1653. In this letter some valuable remarks are to
be found on the method of leading the dumb to the significa-
tion of words ; and’ yet, the name of Datcarno is not once
mentioned to his correspondent.

If some of the details and. digressions in. this note should be
censured, as foreign to the principal design of the foregoing
memoir, I can only plead in excuse, my anxiety to do justice,

even

* In Grarncer’s Biographical History of England, mention is made of a still
earlier publication than the Ars Signoruwm, entitled, “‘ The Universal Character,
by which all Nations in the World may understand one another's conceptions,
reading out of one common Writing their own Tongue. By Cave Brack, Rec-
tor of St Helen’s, in Ipswich, 1657.” This book I have never seen.

The name-of Dalgarno (or Dalgarus, as: it has been sometimes written) ‘is
not altogether unknown. on the Continent. His Ars Signorwm! is alluded to by
Le1snirz on various occasions, and also by FonTenetce i in the Eloge of Lurn-
nitz. His ideas with respect to the education of the Dumb, do not seem
to have attracted any notice whatever. The truth is, ‘they were much’ too
refined and enlightened to be duly appretiated at the period when he wrote..

BORN BLIND AND DEAF. 53

even at the distance of a century, to. the memory of an ingeni-
ous man, neglected by his contemporaries, and already in dan-
ger of being totally forgotten by posterity. To those whose
curiosity may lead them to study his book, the originality of
his conceptions, and the obvious application of which some of
his principles admit to the peculiarities of the case now before:
us, will of themselves suggest a sufficient apology.

APPENDIX,

APPENDIX, containing some additional Commu-
nications relative to James MitcHELL.

NO. I..

Extract of a Letter from Dr Gorvon to Mr Stewart.

Edinburgh, March 30. 1812.

Sm vs few days after you returned to the country, I wrote
to a friend of mine near Forres, putting several queries re-
specting Mircuext, which I requested him to get answered by
Miss Mircuett if possible. I wished in particular to be satis-
fied as to the lad’s behaviour on his father’s death, as what I
had myself seen of his conduct at the funeral, had led me to
differ from Mr Giennie’s information on this point. From
Miss Mrrcuetu directly, I have obtained the following curious
particulars :

At his sister’s request, Mrrcueni was allowed to touch
his father’s body. As soon as he felt it, he shrunk away.
This was the first time he had ever touched a dead human bo-
dy. He has been seen amusing himself with a dead fowl ;
placing it repeatedly on its legs, and laughing when it fell.

He has not shewn any signs of grief in consequence of his
father’s death,

When

56 ACCOUNT OF A BOY

When a tailor was brought to make a suit of mournings for
him, the boy took him into the apartment where his father
had died, stretched his own head and neck backwards, pointed
to the bed, and then conducted him to the church-yard, to the
grave in which his father had been interred.

Being lately very ul, he was put into the same bed where
his father had died. He would not lie a moment in it, but be-
came quite peaceable when removed to another.

On one occasion, shortly after his father’s death, discovering
that his mother was sumed, and in bed, he was observed to
weep.

Three months after the death of his father, a clergyman be-
ing in the house, on a Sunday evening, he pointed to his fa-
ther’s Bible, and then made a sign that the family should
kneel.

Lately, his euieling being from home, his sister allayed the
anxiety he shewed for her return, by laying his head gently
down on a pillow, once for each night his mother was still to
be away ; implying, that he would sleep so many times before
her return *.

Whilst

* It would appear that this is the sign which Miss Mrrcnext usually employs
on similar occasions ; and the ready interpretation of it by her brother, implies,
on his part, no inconsiderable a share of shrewdness and of reflection. I copy the
following parallel incident from a paper of Mr Warpror’s now before me.
(D. S.)

“‘ When his new clothes were all made, I solicited his father not to allow him
to put them on, until I was present. It was signified to him accordingly, that
in two days he should have them. This was done by shutting his eyes, and
bending down his head twice, in order to intimate to him, that he must first
haye two sleeps.”

BORN BLIND AND DEAF. 57

Whilst he was last in London, he happened to be in the
house of a friend of his father’s, who was in the habit of
smoking; and a pipe being given him, he smoked it, and
seemed much delighted. Some little time ago, a gentle-
man came on a visit to Ardclach, who was also in the habit of
smoking, and having tobacco, wished for a pipe. Miss Mrr-
CHELL gave the boy a halfpenny, and permitted him to smell
the tobacco. He understood her signs; went out to a shoe-
maker’s house in the neighbourhood, where pipes were to be
had, and returned with one only in his hand. They suspected
that he had another about him, and» giving him to understand
as much, he at last unbuttoned his waistcoat, and, laughing
heartily, brought out the second pipe. The Sunday after this
occurrence, when his sister gave him a halfpenny, as usual, in
church, to put into the poors’-box, he immediately placed the
halfpenny between his teeth, like a pipe, and laughed ; but his
sister checking him, he dropped it into the box.

He is still fond of the trick of locking people into the shims
or the stable. The patron of the parish, Mr Dunzar Bronte,
(a gentleman who, I have reason to believe, has exceeded all
others in acts of substantial kindness to the Mrrenens. family),
happening lately to visit Ardclach, young Mrrcuett contrived
to make him a prisoner in this manner for a few minutes, laugh-
ing and jumping about all the while. On this particular occa-
sion, it was noticed, that he applied his eye to an aperture in
the door of the stable, as if to observe the motions of the
person within. But although my friend writes me, that the
other day upon holding out his hand to Mrrcuett, the boy
took hold of it; it cannot be conceived, that his sight should
have suddenly so much improved, as to enable him to see any
object in a dark stable, through a hole in the door, without -
the improvement being extremely obvious in other instances.

Wh. VIL” ey a NO. IL

58 ACCOUNT OF A Boy

No. IL.

a

A Series of Questions respecting James Mircueti, proposed by
Mr Guenniz, and answered by Miss Jane Mircuet. *.

Q. 1. Did Mr Warpror operate on the » on only ? or on the
ears also ? iv

A. Mr Warprop operated only on the fight eye. f

Q. 2. Were the drums of the ears pierced during the first or
the second visit to London ?

A. The drums of the ears were pierced during the first visit;
the one by Mr Astizy Cooper, the other by the late Mr
Saunpers of the London Dispensary.

Q. 3. Was it the case, that a musical instrument was play-
ing in the room when his ears were pierced ? and did he at-
tend to it ? oa

A. Some days after his ears were pierced, in a frisiade
house, he applied his ear to a violin, and the sound seemed to
afford him ana vr

A.

* Although some of the information contained in this paper has been already
anticipated in the communications of Dr Gorpon and of Mr Warprop, I have
thought it proper to insert it here at full length ; on account not only of the new
light which it throws on various very interesting and important points, but of
the high authority which it derives from Miss Mircuexx’s name. (D.S.)

+ The following particulars are mentioned by Mr Warprop ie re-
spect to the state of Mrrcuexx’s deafness at the time when he saw him in
London. (D.S.) Sclo
..... © When a ring of keys was given to him, he seized them with great

avidity, and tried each separately, by suspending it loosely between two of his
fingers,

BORN: BLIND AND DEAF. 59

Q. 4. Does the shew a strong desire to examine all objects
by feeling?

A. He does: small 2st he applies to his teeth, and feels

with the tip of his tongue: larger objects he feels with his fin-
gers carefully.

Q. 5. Is he much gratified with a new object ?

A. Some objects do not seem to attract his attention ; others
do; and, where there is any mechanism, he endeavours, by
handling them, to find it out: he discovers a particular fond-
ness for locks and keys.. ;

Q. 6. Does he discover any preference to the handling
of smooth, rough, or pointed things ?

_A. If he does any, it is to smooth objects; when he gets a
bit of rough wood, he endeavours to smooth it with his teeth,
or causes the boy who attends him to smooth it with a knife.

.Q.7. Is he fond of bodily exertion ?
A. He is extremely fond of running, walking, and sti

H2 | Q. 8.

fingers, so as to allow it to vibrate freely ; and after tingling all of them
amongst his teeth in this manner, he generally selected one from the others,
the sound of which seemed to please him most. This, indeed, was one of his
most favourite amusements, and it was surprising how long it would arrest his
attention, and with what eagerness he would on all occasions renew it. Mr
Broveuam, having observed this circumstance, brought to him a musical snuff-
box (a French trinket, containing a small musical instrument, which played airs
by means of a spring), and placed it between his teeth. This seemed not only
‘to excite his wonder, but to afford him exquisite delight, and his father and sis-
ter, who were present, remarked, that they had never seen him so mueh in-
terested on any former occasion, Whilst the instrument continued to play, he
kept it closely between his teeth, and even when the notes were ended, he con-
tinued to hold the box to his mouth, and to examine it minutely with his fin.
gers, ag phe his is eaves and be his countenance great curiosity.”

‘60 ACCOUNT OF A BOY —

Q. 8. Does he discover any sense of danger ?

A. He discovers a sense of danger from fire, — and
sharp instruments.

Q.9. Is it necessary to follow him, to keep titty from
harm ?

A. It is only necessary to follow him, to prevent him from
wandering. h

Q. 10. Has he the knowledge of the use of things ? |

A. He knows the use of all common things, and is pleased
when the use of any thing with which he is not cw erm is
communicated to him.

Q. 11. Has he learned to do any kind of work ?

A. He has not ; further than to assist any of the farm-servants,
for whom he may have conceived an attachment, in any work
in which they may be engaged; particularly in cleaning the
stable. He has endeavoured to repair breaches in the farm
houses; and has attempted to build small houses with turf,
leaving small openings resembling windows. Means have been
used to teach him to make baskets; but he wants application
to finish any thing.

Q. 12. Does hes go from home? and is he fond of doing so ?

A. His greatest pleasure seems to consist in wandering from
home ; but he always returns to his meals.

Q. 13. Is he uneasy when waerety from his friends or at-
tendants ?

A. He discovers much uneasiness when eciieircbak from his
friends, but does not, now, discover uneasiness when he chan-
ges his attendants, though he did, very early in life.

Q. 14. Does he love to associate with boys, and engage in
play ?

_ A. He never associates with boys, nor discovers any incli-
nation to join in their amusements ; but sometimes wishes the
boy

BORN BLIND AND DEAL. 61

boy who attends him, to assist him in floating objects on the
water, &c. He is, however, fond of young children, and takes
them up in his arms.

Q.15. Has he any uneasy feeling of his unfortunate situa-
tion ?

A. He is sensible that his sight is imperfect, baat does not
discover any uneasy feeling of his situation.

Q. 16.. Is he sensible of loud sounds ? or of music ?

A. Of wery loud sounds he is, and seems uneasy at the
time. .

Q. V1, Does he pprehaed the distinction of ranks in socie-
y ait '
_ A. He prefers persons. ea are well dressed, to those aM
ea not ; and would not willingly eat any food in the kitchen.

Q. 18. Has he the sense of ridicule ?

_ A. In some degree he no doubt has ; for imstance, he takes
pleasure in locking the door on people, and confining them ;
_and, if treated in the same manner himself, seems amused, but
if too much teazed, is irritated. .

Q.19. Has he any devotional align: 2

A. He cannot possibly have any ; but-sits, quietly in. church,
and kneels at family-prayers. |

Q. 20. Has he the sense of right. och wrong’ ?

» A. He undoubtedly has; and if gentle means are used to make
him sensible of his having done wrong, he shews sorrow ; but
if harshly treated, is irritated.

No. III.

62 ’ ACCOUNT OF A BOY

No. III.

Tur foregoing sheets were not only printed but cast off be-
‘fore the following letter reached me. ‘T subjoin it, without
any comment, to the papers on the same subject which I have
already laid before the Society; and have only to return my
thanks to the Author, for the trouble he has so'judiciously ta-
ken in recording a variety of minute details, which, to-a su-
‘perficial observer, may appear of trifling importance, ‘but
which will be considered in a very different light by all who
are able to perceive, how strongly they bear on some of the
most interesting questions which relate to the characteristical
endowments of the Human Mind. Solitary as Mircuett is
in the midst of society, and confined, in his intercourse with
the material world, within the narrowest conceivable limits’;
what a contrast does he exhibit,—in those rudiments of a ra-
tional and improvable nature, which we may trace even in his
childish occupations: and pastimes ; ; and more particularly, in
that stock of: knowledge, scanty as it is, which he has been
prompted to acquire by the impulse of his own spontaneous
curiosity,—to the most sagacious of the lower animals, though
surrounded with all the arts of civilized Man, and in the fullest
possession of all the powers of extemal perception |! |

Letter

BORN BLIND AND DEAF. 63

Letter from Dr Gorvon to Mr Srewarr.

Edinburgh, October 26. 1812.
My | dear Sir,

“During my residence in Morayshire, in August last, I did
not fail to avail myself of my vicinity to Ardclach, to visit the
Mirenext. family. I have now to communicate to you, accord-
ing ‘to promise, the additional particulars respecting the subject
of your memoir, which this visit has enabled me to collect.
Some of these, you will easily perceive, are the result of my
own observation on the boy himself; others were obtained
from conversations with his eldest eer whom I considered
myself extremely fortunate in finding at home.
~ Previously to my visit, report had given me reason to ex-
pect, that I should find young Mrrcnety’s vision considerably
improved ; and I had not been long in his company, before I
received very satisfactory proof that this was the case. Ac-
cordingly, I was led to examine his eyes with attention.
Twelve months ago, as I have stated in the supplement to
Professor Giennir’s Account, one could perceive fragments of
the lens very white and opaque, behind one-half of the pu-
pil of each eye; and through the other half, a slighter opa-
city, or a sort of greyish appearance, in the parts situa-
ted farther back. The only change which I could discover,
sufficient to account for the improvement which has taken
place in his vision, is a diminution in this slighter opacity in
both eyes. At present, there is a very white fragment of the
lens, behind the upper half of the pupil of the right eye ; and
behind the lower half, the humours appear ‘almost perfectly
black. In the left eye, there is a dusky-white opacity behind
the lower and inner half of the pupil; and behind the upper

and

G4 ACCOUNT OF A BOY

and outer half, the humours are of a dark grey. The pupils
contraet and dilate as usual, on varying the. quantity of light.
It is not easy to determine the exact degree of vision which
he now enjoys.. He sees those bodies only which have consi-
derable brightness, or dark-coloured bodies placed on a bright
ground. Consequently, of the various objects which usually
surround him, he sees such only as are not very minute, and
are placed within a short distance of his eyes. He could
distinguish a crown-piece at the distance of two or three feet, -
and a person’s face at the distance of six. But it seems obvi-
ous, that he does not perceive distinctly the limits of any ob-
ject, however bright. For as soon as, guided by his own ob-
scure vision, he has reached any thing with his hands, he no
longer regards it with his eyes; but, as if he were yet totally
blind, examines it solely with his fingers, tongue, lips, and
nose. |
That he can now distinguish differences in the kinds of
light or in colours, seems very evident from an amusement in
which, his sister told me, he sometimes indulges,;—matching
bodies of the same colour together. One day, for example,
having a bunch of the flowers of wild mustard in his hand, he
was observed to approach an officer who was near him, and,
with a smile, placed the flowers in contact with the yellow
part of his epaulette. Frequently, too, he is seen gathering in
the fields a number of flowers of the same kind ; the blue-bot-
tle, for example, or the corn-poppy, or the marigold. It ap-
pears, however, that it is only the brighter colours he is capa-
ble of distinguishing ; and of these red seems to be his favou-
rite. -A red object attracts his notice more, and he looks at
it longer, than any other. Of the female parishioners who
pass the manse on their road to church on Sunday, he is most
apt to follow those who are dressed in red cloaks. Miss Mir-
CHELL

BORN BLIND AND DEAF. 65

CHELL is of opinion, that he rather dislikes darkness; for she

has observed, that in moving from one part of the house to
another after night has come on, his step is hurried; and
that he seems happy in reaching an apartment where there is
a candle or a fire.

I observed, that he judges of the direction of a body by
sight, with invariable accuracy ; but when an object whose real
magnitude is not known to him, is placed before his eyes, he
does not seem capable of estimating its distance, for the first
time, with any degree of correctness. When I held a silver
snuff-box about two feet from his face, he put out his hand
exactly in the direction of the box, but moved it forwards very
gradually until it came in contact with it. These circum-
stances are just what we should before-hand have expected to
find ; and such also, I imagine, as may be remarked of all per-
sons who are nearly blind, from a similar cause. The per-
ception of the direction of bodies, which obviously depends on
the particular part of the retina which is affected by the rays
they emit, may be obtained equally (if the bodies be seen at
all) from the weakest as from the most perfect vision. But
MircueLt’s vision is too obscure to enable him to perceive
those minute differences in the colour and intensity of light, by
which persons having perfect sight, judge of the relative dis-
tance of luminous bodies.

_ On the whole, it appears obvious, that his sight, although
yet far too imperfect for any attempt to address him in a visi-
ble language, is considerably improved within these last twelve
months. Did the boy’s dispositions admit of it, I should now
be inclined to recommend still more earnestly than before,
that another attempt should be made, to remove the cataracts
from his eyes, and I am much less disposed than formerly to
fear, that there is any radical imperfection in the optic nerves.

Here

66 ACCOUNT OF A BOY

Here it may not be improper to mention, that his sister is
convinced, that he sees some objects better by moon-light
than during the day; a circumstance which seems to shew,
that the opacity in his eyes is, as in other cases of cataract,
merely local ; so that when the pupil is much dilated, some
rays of light reach the retina, through those more transparent
parts of the humours which are farther distant from the axis
of vision than the portion that is opaque. |

His powers of Hearing remain as imperfect as ever. He
still continues the practice of striking hard bodies against his
teeth ; but on further reflection, I think it not unlikely, that
he may have another object in view in this experiment, be-
sides that of procuring a sensation of sound. It is not at all
improbable, that he discovers differences in the hardness of
bodies in this manner. For there is a very distinct sensation
felt towards the roots of the teeth themselves, when they are
struck with a hard substance, resulting probably from an affec-
tion of the nerves of the membrane lining their inner cavity,
and this sensation is different according to the hardness of the
body. I have little doubt, that he could by this kind of feel-
ing alone, very easily discover that lead was softer than steel,
and steel harder than ivory; although all these substances
would feel equally hard to his proper organs of touch. But
even supposing that he does not avail himself of this sensation
in the teeth themselves, it is probable that he strikes bodies
against these organs, not so much to try whether they will
cause sound at all, as to observe what kind of sounds they will
emit; from which he may infer various other properties,
which experience has taught him, are eon connected
with the particular sounds emitted. .

His manner of examining any object that is new to him, is
precisely the same now that it was four years ago, when I first

saw him. When it is put into his hand, he runs it over with
the

BORN BLIND AND DEAF. 67

the points of his fingers ; then applies it to his mouth, and in-
sinuates his tongue into all its inequalities, thus using it as an
organ of Touch as) well as Taste; and, lastly, if it is a body
that admits of it, he rattles it between his teeth. All this is
done with singular rapidity. In fact, he loses but little time,
in discovering, by the actual use of his organs of touch, taste,
and smell, those qualities of bodies which we are content to in-
fer from their visible appearance alone.

. His sense of smell is unquestionably extremely acute. But
I have not been able to learn any fact which could lead me to
believe, that he could, in a room at least, discover a person by
this sense alone, at the distance of twelve feet. It has been
said, that he could follow the footsteps of another person for
two miles, guided merely by smelling. But his sister assures
me, that there is no foundation for this report. As to a power
of determining the direction of an object, by some distinct qua-
lity in its odour, like that quality in sound by which we disco-
ver the direction of a sounding body, I could not perceive that
he enjoyed any such power more than other persons. Indeed
it is not likely that his faculties should differ in kind from our
own, however much they may in number and degree *.

- Since his sight has begun to improve, his excursions have be-
come bolder and more extensive. He has sometimes wandered

upwards

* Hic Adolescens, annum nunc agens Xviii, et optima semper usus valetudine,
vegetus est, et admodum robustus : quin et solita ztate pubescere visus est, par-
tibus genitalibus ut in viris se habentibus ; neque dubitari potest quin brevi fu-
turus sit éxrwyey, labiis et mento densa jam inumbratis lanugine. _ Curiosé autem
percontanti famuli et amici (masculini scilicet sextis, quos solos de his rebus in-
terrogare fas erat) omnes mihi testabantur nihil se observasse, unde colligerent
illum Veneris stimulum unquam sensisse, vel differenti sexs notionem ha-
buisse,

12

68 ACCOUNT OF A BOY

upwards of three miles from home. In all these expeditions, he
proceeds in a great measure without a guide. But a boy is
appointed to follow him, and keep him constantly in view ;
and Mircnett has the good sense, when he perceives any
thing which he imagines to be a serious obstacle in his way, to

wait staat his little Sellonic comes up to his assistance.
Lately, on the road near the manse, he met a person, riding

on a horse which had been bought a few weeks before from
his mother ; and on coming up to the animal, and feeling it,
he seemed instantly to recognise it. The person immediately
dismounted, in order to see how MircHet would behave ; and
he was much amused to find, that he led the horse to his mo-
ther’s stable, took off his saddle and bridle, put corn before
him, and then withdrew, locking the door, and putting the key
in his pocket.

When he wishes to communicate his ideas to any one near
him, he uses natural signs; and it is curious to observe, that
most of these signs are addressed to the sight of those with
whom he converses. This fact, it appears to me, shews very
clearly, that he is aware that the powers of vision enjoyed
by others are superior to his own; and hence it is not unrea-.
sonable to hope, that his reflecting on his inferiority in this
respect, when his reason has become more matured, may be
the means of inducing him to submit, more placidly than he
has hitherto done, to any endeavours for the improvement of
his sight. :

The following are a few examples of his signs. As soon as
I began to examine his eyes, opposite to a window, he turned
towards his sister, and stretched out his arm to its full extent
laterally from his body. This, his sister informed me, is his
usual sign for London. It is obviously the natural expression
of distance ; and there is no need of pointing out the associa-
tion which must have led him to use it on this occasion.

When

BORN BLIND AND DEAF. 69

When he would express that he has ‘been on horseback, he’
raises his foot, and brings the fingers of each hand together un-
der the sole, in imitation of a stirrup. He places his hand on
his mouth to signify his wish for food ; and when he would go
to bed, he inclines his head sideways, as if to lay it on a pillow.
When I arrived at Ardclach, young Mircuet was not at home;
he had wandered to the shoemaker’s, several hundred yards
distant, where he was sitting in anxious expectation of a pair
of new shoes. He was brought to the manse; but after he
had remained with us contentedly in the dining-room for about
half-an-hour, he shewed an anxiety to get away ; and as he mo-
ved towards the door, he made use of a sign, from which no
one could fail to discover whither he was going. It was, an
exact imitation with his arms, of a shoemaker’s motion when
he pulls his thread.

All the signs employed by others in order to convey ideas
to him, are addressed to his organs of touch. ‘The most im-
portant, certaialy, of these signs, are those which his sister has
invented, to express her approbation or disapprobation, her as-
sent or dissent. Miss Mrrcuertz’s explanation of them is ex-
tremely satisfactory. Her brother has always been particular-
ly attached to her, and she has always had most influence over
him. He courts her good opinion. When she would signify
to him her highest approbation of his conduct, she pats him
much and cordially on the head, back, hand, or any other part
of the body. This expression more sparingly and less fer-
vently bestowed, signifies simple assent ; and she has only to re-
fuse him these signs of her approbation entirely, and to repel
him gently, to convey to him in the most effectual manner the
notice of her displeasure.

When I suggested to Miss Mrrcuetx that it would be a
highly interesting task, though doubtless a difficult and tedious

one

70 ACCOUNT OF A BOY

one, to teach her brother the meaning of written words, and
mentioned briefly the outlines of a plan for that purpose; she
expressed the utmost willingness to undertake any attempt of
this kind, but anticipated the chief obstacle to the design from
his want of application. Still 1 cannot help thinking, that this
obstacle would probably diminish, as soon as he felt the magic
power ofa few words. Perhaps a trial might be made ac-
cording to some such plan as the following.

First, young Mircurtt might be provided with a horn-~
book, on which the letters, of the alphabet have been cut
in relief. His sister might then begin, by tempting him with
the prospect of some article of luxury, a piece of sugar for ex-
ample, or a toy ; but before gratifying him with the possession
of it, she might take hold of his fore-finger, and conduct the
point of it over all the letters composing the name of the ar-
ticle. This being frequently repeated, I have little doubt that
he-would soon point to the same letters when the same object
was held in prospect; and at last, use the sign to procure the
luxury. Were one step of this kind gained, it is not un-
reasonable to expect, that he might in time be made to un-
derstand the meaning of every word in our language, whether
expressive of one or many ideas. Such words are of course
excepted, as express ideas which he cannot possibly have ex-
perienced, from the imperfections of his sight and hearing.
An advantage would attend the use of the horn-book proposed,
that if the letters were painted black, Mircne.i might com-
municate by means of it with persons at a considerable dis-
tance: Supposing him to have acquired a language of this
kind, two others, if necessary, might afterwards be connected
with it. The first would consist in tracing the letters of words
on the palm of his hand, with the point of one’s finger ; and

: the

BORN BLIND AND DEAF. cal

the second, of the common speech on the fingers. But how
great an acquisition would the principal language alone be,
without any such auxiliaries !

Several circumstances occurred, during my visit, which
shew, how perfectly susceptible he is of pleasure from joking,
or playing with him, or from any thing ludicrous in the ideas

communicated to him. Twice or thrice when his sister per-

ceived that he was crossing the room to go away, she stepped
to the door unperceived by him, to prevent his escape. When
he found her there before him, he stepped back smiling, and
seemed to take this sort of teazing in perfect good humour.
I had given him my whip, with which he seemed pleased ; and
once or twice his sister took him by surprise, and pulled it
smartly out of his hand. He immediately shewed by his
smiles that he knew who had robbed him ; and quickly catch-
ing his sister, he endeavoured to wrest the whip from her.
The joke obviously amused him very much ; but Miss Mrr-
CHELL assured me, that it would have given him offence to
have repeated it more frequently. An uncommonly large
Newfoundland dog, belonging to a gentleman who accompa-
nied. me, had got, into the room; and nothing could bé more
expressive of surprise than young MrrcHe’s countenance,
when he first felt, this animal. His sister observing this, im-
mediately, with great, quickness, took hold of his arm, and
stretched it above, his head, a sign which, it seems, he uses to
denote mounting a horse., He instantly understood her mean-
ing, and laughing, made a motion as if he would bestride the
GOs xxi .

_ New clothes are still among Mircuetx’s greatest sources of
delight.. After his) measure has been taken, it would seem
that every hour is full of anxiety until the new suit is in his

possession.

72 ACCOUNT OF A BOY

possession. Nothing else appears to occupy his mind. He
literally persecutes the tailor or the shoemaker, until his shoes
or his coat is finished. He is their guest morning, noon, and
night, until the last stitch is drawn.

Before leaving Ardclach, I took an opportunity of conver-
sing very fully with Miss Mircnetx relative to her brother’s
conduct at the period of his father’s death. Her answers to
my inquiries on this point, corresponded exactly with the in-
formation she was so kind as communicate to me through my ~
friend Mr Lauper Dick of Relugas, in March last, and which
I transmitted to you immediately on receiving it. She told
me, that when her brother was permitted, by her direction, to
touch his father’s dead body, he shrunk from it with surprise,
but without expressing the slightest signs of sorrow. She
"assures me also, that he felt the body after it was placed in the
coffin, but without betraying any emotions of grief. On the
evening, however, after her father’s funeral, she herself saw him
go down to the grave, and pat the turf with both his hands ; but
whether he did this from affection, or intended it merely
as an imitation of beating down the turf, she feels unable to
decide, as she was not near enough to him to discern the
expression of his countenance. For several days afterwards, it
would appear that he returned repeatedly to the grave ; but
gradually discontinued his visits. It is worthy of remark, how-
ever, that he has regularly attended every funeral that has since
taken place in the same church-yard. The report, therefore,
which I have stated at the conclusion of the supplement to
Professor Giennie’s Account, of his having shed tears over his
father’s grave, seems entirely without foundation. Miss Mrr-
‘CHELL authorises me to say, that neither on this nor on any
other occasion, has she herself seen her brother shew any une-
quivocal marks. of sorrow for his father’s death. Yet her

friend,

BORN BLIND AND DEAF. 13

friend, the Reverend Mr Camprett of ‘Ardersier, lately inform-
ed her, that he saw her brother standing in the porch shedding
tears, immediately after quitting the apartment in which his
father’s body was lying, previous to the funeral.
On the whole, however, I have not been able to discover the
slightest reason for altering the opinion I have always entertain-
ed respecting the state of young Mircuetx’s feelings on the day
of the funeral. It was my strong conviction of the truth of this
“opinion, and thinking that Professor GLENNIE might have been
furnished with the materials of his Account from some one who
had not enjoyed the same opportunity of judging as myself;
that led me, in the supplement to that, Account, to doubt in
some degree the accuracy of his information on this point. I
have since found, however, that the whole of Professor Guen-
NIE’S Memoir was communicated by my friend Mr Macrar-
LANE, who was present, as well-as myself, on that melancholy
occasion. I would now observe, therefore, that though I am sorry
to, differ in opinion from a gentleman who has written so able a
_ detail of some other parts of Mrrcuetx’s history, my perfect
knowledge of his candour and liberality embolden me to say, that
I think ‘ee is mistaken in this particular; and that he has inter-
preted into expressions of grief in young Mircuet, what were
merely expressions of curiosity. On this subject I have com-
municated with my friends Mr Lauper Dick of Relugas, Mr
Smytu of Earlsmill, and the medical attendant of the family,
Mr Srrartu, surgeon at Forres ;—gentlemen who also were pre-
sent at the funeral, and who are more familiar even than I am
with young Mrrenerz’s countenance and expression; and I
find, that their opinion coincides exactly with mine. His mo-
tions at the coffin were equally visible to us all. But we
did not attribute his placing his arms around it, to any emo-
tion of sorrow, of which there appeared to us not the slightest
Vox. VIL. K trace

74 “ACCOUNT OF A BOY

trace in his countenance, but to the same motive that led him

the very next moment, to trip lightly towards us, and smiling-

ly feel our clothes all over—the pleasure he experienced in the

examination of objects that were new to him. My friend Mr

Lauper Dick, who has accompanied me in all my visits to Ard-

clach, and whose interest in the family, and kindness towards

them, have been equally great, has favoured me with a few re-

marks, in a letter on this subject, which appear to me so just, that |
I shall take the liberty to quote them. “ From my observations,”

he writes, “‘ made at the time, with all the attention which an ex-

treme interest in the boy could excite, my opinion certainly

is, that he was occupied with the coffin merely as being a

body of a shape and surface different from any thing he had

“ before met with ; and that he betrayed no emotions of grief.

‘“¢ When the procession moved onwards, all his gestures seem-

“ ed more those of @ playful boy in good spirits, than those

“ of an afflicted youth, conscious of the awful change which

‘«« had taken place upon his parent. As it is certain that he

“ had never felt a dead body, nor had any opportunity of
“ learning the object of burial before; it appears to me, that

“ we,cannot imagine him to have experienced any emotion of
“ orief at his father’s funeral, lel also supposing him to

fave had an innate idea of death.

I am, my dear Sir, with great regard, yours truly,
JoHn Gorpon.

‘Postscript.

Before sending you this letter, I transmitted a copy of it to
Miss Mrrcuecz, for her perusal and correction ; and I have
much pleasure in adding the following extracts from her very

bliging and satisfactory reply.
arn “ Aoreeably

oe
.i9
‘i

«

BORN BLIND AND. DEAF. 75

* Aoreeably to your request, I have read your letter to Pro-
fessor Stewart with as much attention as the short time it
has been in my possession would admit of ; and I certainly
think you have stated those facts I informed you of, respect-

ing my brother, most correctly.
»“© My brother seems to be very well pleased with his change

of residence *, and goes on much in the same way he did at
Ardclach ; that is to say, wandering for several miles round
the small town we live in, or amusing himself by visiting the
different carpenters’ or other tradesmens’ shops within his
reach, and handling their implements, or trying to discover
what they are engaged about. He has. not yet discovered
any anxiety to return to Ardclach, and is, I think, quite as
happy as when there.”

* Mrs Mircue.i and her. family have within these few months left Ardclach

to reside at Nairn.

K 2. INO. EN

76 ACCOUNT OF A BOY

No. IV.

Wuitz employed in revising this concluding sheet, I had
the pleasure of receiying the following letter from my friend
Sir James Macxiytosu. It is unnecessary for me to mention
the satisfaction I feel in attracting that notice to the Subject of
my Memoir which his name cannot fail to ensure.

>

Leiter from Sir James Macxrntosu to Mr Srewarr.

Edinburgh, 5th November 1812.
My dear Sir, .

In consequence of our conversation at Kinneil in August, L
called on Mrs Mrrcuetu after my arrival in Nairnshire, and on
the 9th of October I had an interview with James Mircnennz,
and his sister Miss Mrrcne.u, which lasted for several hours.
I directed my inquiries to every point which seemed important,
in the corporeal or mental state of this unfortunately interest-
ing young man.

The result, however, is little more than a needless corrobo-
ration of the accounts which you have already received ; espe-
cially those from Dr Gorpon, who seems to have conducted
his observations with much philosophical discernment and ac-
curacy.

During the vacancy in his father’s parish, the parishioners
assembled on Sunday for public worship and mutual instruc-
tion, and one of the elders prayed with a loud and shrill
voice, which was observed to give great uneasiness to Mir-

CHELL.

BORN BLIND AND DEAF. 77

cHELL. This occurred several times, so that there appears
no reason to consider it as an accidental coincidence.

. Though his ordinary conduct be decorous, it seems to be in-
fluenced by habit and instruction rather than by feelings of de-
licacy. When the females of his family are undressing, he has
been observed to turn aside. There are no males in the house.
But in an opportunity which ‘has lately occurred, he has been
thought to shew a similar disposition in the case of males.

I have seldom seen an imperfection ofthe senses attended
by so little an air of defect in the countenance. Singular as it
may seem, I should even venture to call his features intelli-
gent. He handled every part of the room in which we sat,
with indications of an inquisitive mind. .

His sister is a young woman of most pleasing appearance
and manners, distinguished by a very uncommon degree of
modesty, caution, and precision, in her accounts of him; and
probably one of the most intelligent, as well as kindest com-
panions, that ever guided a being doomed to such unusual, if
not unexampled privations.

You will not think me fantastic for adding, that the ha-
bitual exercise of ingenious benevolence seems to me to
have left its traces on her countenance, and to have bestowed
on her naturally agreeable features, an expression more de-
lightful than beauty. Her aversion from exaggeration, and
her singular superiority to the pleasure of inspiring wonder,
make it important to the purposes of Philosophy as well as of
Humanity, that she should continue to attend her brother.
Separation from her would indeed be an irreparable calamity to
this unfortunate youth.. By her own unaided ingenuity, she has
conquered the obstacles which seemed for ever to preclude all
intercourse between him and other minds; and what is still
more important, by the firm and gentle exertion of her well-earn-

ed

18 ACCOUNT OF A Boy, &ev

ed. ascendant over him, she spares him much of the pain which
he must otherwise have suffered from, the occasional violences
of a temper irritated by a fruitless struggle to give utterance to
his thoughts and wishes ; disturbed still farther by the vehe-
mence of those gestures which he employs to supply the defi-
ciency of his signs, and. released from that restraint on anger’
which we experience when we see and hear its excesses disap-
proved by our fellow-creatures. _
I am, my dear Sir, with the truest esteem,
Yours most faithfully,

J. Mackintosu.

II. On the Vertical Position and Convolutions of certain Strata,
and their relation with Granite... By Sir James Hart,
Bart. Pr.R.S. Ep. & F.R.S. Lonp.

[ Read February 3. 1812. ]

HE tract of country extending across this island, from
the sea-coast of Galloway to that of Berwickshire, cone
sists, with little interruption, of that species of rock, which has
of late been most generally known by the German name of
Grauwacke. But as this rock does not differ essentially from
what in Cornwall is called Killas, I am disposed, in, concur-
rence with several members of this Society, in particular with
Mr Axtan, who has of late been in Cornwall, and has paid
particular attention to that subject, to reject the uncouth term
Grauwacke, and adopt that of Killas, as being more congenial
to our language. vt |
The continuation is so unbroken, that I believe it would be
practicable to walk from one sea to the other, without tread.
ing upon any rock but killas ; and as its character is identical
throughout, we seem to be authorised, in every view of mine-
ralogy, to look upon the whole | as one with respect to origin
and

80 ON THE CONVOLUTIONS OF STRATA,

and history ; so that observations made at any one part of the
range, may, with confidence, be applied to the rest.

- There are but few exceptions to this general rule, which
have come to my knowledge. At the Rae Quarry in Peebles-
shire, near the Crook Inn, a Limestone containing shells oc-
curs, interstratified with killas ; and in the stewartry of Kirk-
cudbright, there are three Granitic districts in the midst of this
rock, whose relations with it exhibit some interesting facts,
which will occupy the second part of this paper. A granite
mass also occurs within the range of this same mass of killas,
at Priestlaw on the Water of Fasnet, in the mountainous part
of East Lothian.

The killas consists everywhere of an assemblage of strata of
various thickness, from several yards to the minutest leaf of
slate. It is in general of a dark-blue colour, and, when exa-
mined, is found to consist of a congeries of fragments, which
bear the most undoubted proofs of having been deposited in
an horizontal position. The strata lie parallel to each other,
but are ‘everywhere far from being horizontal, their pre-
vailing and best known position being vertical, or nearly
so. They are often bent, however, at various angles, fre-
quently very acute, and sometimes with the strata nearly
doubled upon themselves. In all the inland part of this
range, the rock appears so partially, shewing itself only in ri-
ver-courses, OF in quarries, that it is difficult to obtain any
correct information as to the position of the strata, which fre-
quently exhibit great seeming irregularity, and which cannot
be described, without making use of language which at first
sight bears an appearance of contradiction in terms. Thus
it not unfrequently happens, that one set shews itself in
a position, at the surface, nearly erect, but having a decided
dip to the east; and that in the immediate neighbourhood,

another

AND THEIR MEETING WITH GRANITE. $1

another set occurs in a position similar to the first, but having
a no less decided dip to the west. ;

On the shore of the sea, however, where these rocks are
bare, and exposed in such a manner, that our view can em-
brace at once a considerable extent of the mass, the general
structure becomes apparent, and we are enabled to give a ra-
tional account of these seeming anomalies.

This opportunity of observation, occurs with peculiar ad-
vantage on the coast of Berwickshire, where the lofty cliffs
which extend from Fast Castle eastward to Gun’s Green near
Eyemouth, present to view a cross section of these strata, by
which their position is seen to possess much more method and
regularity than the inland rocks would have led us to expect.
The strata here exhibit a succession of regular bendings, and
powerful undulations, reaching from top to bottom of the
cliffs, two or three hundred feet in height. These are occa-
sionally interrupted, as might be expected, by the irregulari-
ties of the coast, by shifts and dislocations of the beds, and
sometimes, as happens at St Abb’s Head, by the intervention
of whinstone ; or occasionally of porphyry.

Notwithstanding these interruptions, I reckoned, (in an
excursion to that coast, made last summer with my son
Lieutenant Basit Haut of this Society), sixteen distinct
bendings, in the course of about six miles, each of the largest
size, and reaching from top to bottom of the cliffs, their cur-
vature being alternately concave and convex upwards. Plates
I, I] and II]. are from drawings made on the spot. Fi g.1. Plate
I. shews a general view, taken at sea, at some distance off the
point of Fast Castle, which appears upon the right hand. Plate
II. shews a near view of part of the same scene, representing a
spot called the Brander Cove, in which one of these convolu-
tions, concave downwards, is conspicuously seen, The rock

Vot. VII. L upon

82 ON THE CONVOLUTIONS OF STRATA,

upon the right, on which Fast Castle stands in fig. 1.. Plate I.,
exhibits also one of the convolutions concave downwards,
and similar to that: of the Brander Cove, seen on the left.
Plate III. represents another rock of the same coast, at a
place called Whapness, near Gun’s Green, in the neighbour-
hood of Eyemouth. Here there are four bendings ; two con-
vex upwards, and two convex downwards, lying close to each
other ;. and fig. 2. Piate I., represents a rock in the same neigh-
bourhood, in which a variety of convolutions are distinctly seen.

We have thus a specimen of that part of the coast which con-
sists of killas; the whole being a succession of similar bendings,
alternately concave and convex upwards ; and the curvature
of the mass is, in general, (as Mr Piayrair has well obser-
ved, Illustrations, art. 204.) simple ; that is to say, these bend-
ings are performed in one direction only, and round axes that
seem to lie horizontally, and parallel to each other.

These strata, in common with all those of killas, seem to
have been originally deposited in a position nearly horizontal,
and many of the particular beds represented in these sketches,
possess that peculiar undulation on their surface which we
meet with on a sandy beach, when the tide has left it, and
which affords the most unequivocal indication of aqueous de-
position. There is reason to believe also, that the strata, con-
stituting these convolutions, though now detached from each
other, have at one period lain in continuity, and horizontally ;
that by the exertions of some powerful mechanical force, they.
have been compelled to assume their present contorted shape ;
that their continuity still exists below, and would be seen, could
we penetrate into the mass under the level of the sea; the in-
terruption of their continuity upwards, haying arisen from ia
removal of part of the rock, by some of those revolutions which

have

AND THEIR MEETING WITH GRANITE. 83

have every where agitated and corroded the surface . our
globe.

In order more fully to illustrate this arrangement, I have
drawn in figure 1st, Plate IV. an ideal portion of a coast similar
to that which we have been describing ; and in figure 2d, the
same has been exactly repeated in black lines. But in this
last figure, I have introduced a continuation of each of the
strata in dotted lines; so that every one of them is rendered
completely continuous from end to end.

This theoretical completion of these forms, may be of ser-
vice in accounting for the anomalous circumstances already
mentioned, as belonging to the strata of killas. In particular,
we may thus readily account for the abrupt change of dip
from east to west. Thus, in figure 1. Plate IV. we see the
strata a b, and c d, dipping rapidly to the east, and those at
ef, and gh, as rapidly to the west; yet, at their outgoings,
or appearances at the surface, they are very little removed
from each other ; and if the middle point, where the convolu-
tion takes place at m, were hid from the view or removed, the
appearance would be completely paradoxical.

Making allowance for shifts, and various interruptions,
great part of the coast may be thus explained : but this simple
curvature, though general, is by no means universal in the
killas ; as appears in some places upon this coast, to the east- —
ward of EKyemouth, at Gun’s Green, where the axis of convo-
lution is very irregular, and is sometimes vertical ; and also in
Galloway, where the strata present. to view much more irre-
gularity. | But these anomalies, though more complicated,
seem all to be of the same class, and to denote the influence
of similar actions, as I shall endeavour to shew in the course of
this paper. ;

L2 In

84 ON: THE CONVOLUTIONS OF STRATA,

In reducing these irregular forms into system and connec-
tion, one object, of no small consequence in geology, seems to
be obtained ; but it would be desirable, if possible, to go a step
farther, and to discover by what means this peculiar arrange-
ment has been brought about. For this purpose, it will be
necessary to shew, first, That this peculiar conformation may
be given to a set of horizontal beds by a mechanical force: of
sufficient strength ; and, secondly, That there are rational
grounds for believing, that such a force has been actually
exerted in this case. I have now, and formerly, tried to esta-
blish the first point by experiment ; and I shall endeavour to
vindicate the second by a train of geological reasoning, found-
ed upon some volcanic phenomena.

In the year 1788, when I had the pleasure of visiting the
coast of Berwickshire, in company with Dr Hurron and Mr
Prayrair, it occurred to me, that this peculiar conformation
might be accounted for, by supposing that these strata, origi-
nally lying flat, and in positions as nearly level as might be
expected to result from the deposition of loose sand at the
bottom of the sea, had been urged when in a soft, but tough
and ductile state, by a powerful force acting horizontally ; that
this force had been opposed by an insurmountable resistance
upon the opposite side of the beds,—or that the same effect
had been produced by two forces. acting in opposite direc-
tions; at the same time that the whole was held, down by a
superincumbent weight, which, however, was capable of being
heaved. up by a sufficiently powerful exertion.

By either of these modes of action, I conceived, that two
opposite extremities of each bed being made to approach, the
intervening substance, could only dispose of itself in a succes-
sion of folds, which might assume considerable regularity, and.
would consist of a set of parallel curves, alternately convex and

concave

AND THEIR MEETING WITH GRANITE. . 85

concave towards the centre of the earth *. At the same time,
no other force being applied, any two particles which lay
with respect to each other, so that the straight line joming
them were horizontal, and at rignt angles to the direction of
that active force, would retain their relative position, and of
course that line would maintain its original straightness and
horizontality ; and thus the forces exerted being simple, or, if
compound, tending, as just stated, to produce a simple result,
the beds would acquire the simple curvature ascribed to them
by Mr Prayratr, and which belongs to them, in the imme-
diate neighbourhood of Fast Castle; whereas, in Galloway,
and in some parts of our coast, particularly near Gun’s Green,
to the eastward of Eyemouth, where the curvature deviates
from that simple character, and becomes in the utmost degree
irregular, we must conceive tlie force to have been more com-
plicated, or most probably to:have acted at successive pe-
riods.

This conjecture no sooner occurred, than I endeavoured to
illustrate my idea by the following rude experiment, made
with such materials as were at hand. Several pieces of cloth,
‘some linen, some woollen, were spread upon a table, one
above the other, each piece representing a single stratum;
-a door (which happened to be off the hinges): was then. laid
above the mass, and being loaded with weights, confined it
under a considerable pressure, (fig. 3. Plate LV.), two boards
being next applied vertically to the two ends of the stra-

~ tified

* Tam aware, that this expression of parallel curves is irregular ; but I can
find no other mode of conveying the idea. It is not easy to trace, a priort, what
form would be assumed by these beds, supposing the whole to be held down by
a force so powerful as to prevent any vacuity. It is enough, however, for our
present purpose, that the forms of nature correspond with those obtained in an.
experiment soon to be mentioned.

86 ON THE CONVOLUTIONS OF STRATA,

tified mass, were forced towards each other by repeated
blows of a mallet applied horizontally. ‘The consequence
was, that the extremities were brought nearer to each other,
the heavy door was gradually raised, and the strata were con-
strained to assume folds, (fig. 4. Plate 1V.), bent up and
down, which very much resembled the convoluted beds of
killas, as exhibited in the craggs of Fast Castle, and illustrated
the theory of their formation.

I now exhibit to the Society a machine, by which a set of
pliable beds of clay are pressed together, so as to produce the
same effect, fig. 5.; and I trust, that the forms thus obtained
will be found, by gentlemen accustomed to see such rocks, to
bear a tolerable resemblance to those of nature, as shewn in
“fig. 6., copied from the forms assumed in the machine, by an
assemblage of pieces of cloth of different colours.

It still remains for us to consider how this horizontal thrust
may have been produced. It will be found, I conceive, to
arise, as a natural consequence from Dr Hurron’s original
hypothesis, according to which our continents have been rai-
sed from the bottom of the sea, and elevated to their present
positions, by the internal action of the same heat which shews
itself externally in volcanoes.

The most obvious mode of investigating these internal ac-
tions, in pursuance of the Huttonian view, is to study the ex-
ternal volcanic phenomena, and to consider what variations
and modifications would be produced upon these last by the
circumstances attending the subterranean action of the same
powers.

With this view, I beg leave once more to solicit the atten-
tion of the Society, to a scene which I have mentioned in for-
mer papers, and to refer to some plates representing it, which
I have given in the sixth volume of our Transactions, in my

paper

AND THEIR MEEETING WITH GRANITE. 87.

paper “ On the Effects of Heat modified by Compression.”
This scene, as viewed in the Atrio del Cavallo, (Plate V..
volume vi. figs. 41, 42, 43, and 44.), exhibits in nature a com-
plete section of the old volcano of Vesuvius, now called Som-
ma. The mountain is there seen to be composed of a succes-
sion of beds of lava and of cinders, the lava occupying only a
fourth or a fifth part of the mass, which is traversed vertically,
but irregularly, by numerous rents filled with solid lava ;.
these rents, as 1 have endeavoured to prove, having undoubt-
edly served. as the pipes. through which lateral eruptions have
been discharged.

_ Each of these rents would continue open during the course:
of the particular eruption by which it was formed, and the la-.
va would flow freely through it; but when the eruptive im-
pulse ceased, it would remain full of the liquid lava, which
would congeal, so as to leave the rent, as it now appears,.
completely filled with hard and solid rock.. This new sub-.
_ stance welding itself firmly to the extremities of the beds.
of lava which-had been broken across, would bind them. toge-.
ther into a species of net-work, and thus the injury done to:
the mountain by the formation of-the rent, would be repaired,.
and much more than repaired ; so that when a new eruption.
_ was directed to the same quarter, it would be less able to pe-
netrate than before, and the eruption would be restrained till.
a fresh rent was effected in some other part of the mountain.
A new eruption must thus, in every case, be an act.of vio--
lence ; and we see how a lateral eruption may. be followed, as-
frequently happens, by a discharge of lava from the summit.
of the mountain, which could not have taken place, had the-
first lava continued fluid, since it would never have ceased in:
that case to flow through the lowest aperture, whereas, in:

consequence:

88 ON THE CONVOLUTIONS OF STRATA,

‘consequence of the congelation of its upper part, that aperture
is closed.

What is true of volcanoes, must be no less true of those
internal operations, which, according to the Huttonian theory,
have been the means of raising all the rocks and mountains
from the bottom of the sea into their present situation; and
by which the unstratified substances have penetrated the stra-
ta, and filled the rents formed in them, producing the veins or
dikes so common in this country, just as we have seen the
lava of Mount Somma filling the rents through the beds of
lava and of cinders.

It cannot be doubted, that the secondary strata must
have been greatly strengthened in this way. We may be sa-
tisfied of this, by looking at any great dike of whinstone (such
as that of twenty or thirty yards in breadth, now opened on the
north side of Edinburgh, as a quarry for pavement), crossing
and connecting substances of every variety of hardness; also
at the two small dikes which appear crossing the loose shale
in the bed of the Water of Leith, close to the two mineral
springs.

The introduction of this new substance, and the heave of
the superincumbent mass, which is its necessary consequence,
have been productive of several very important results, which |
shall be the subject of a future communication to this Socie-
ty. Let us confine ourselves at present, however, to the con-
volutions of the killas.

According to the Huttonian theory, that loose assem-
blage of sand of various qualities, which was destined to give
birth to strata of every sort, from gneiss to sandstone, lying
originally in a position nearly horizontal, as deposited in beds
at the bottom of the sea, and being acted upon from below,
on successive occasions, by a heat of great intensity, must be

conceived,

AND THEIR MEETING WITH GRANITE. 89

conceived, in consequence of the progress upwards of that
heat, to have possessed at any particular moment a great va-
riety of intermediate temperatures, between that intense pitch
and the ordinary heat of the sea. Owing to these varieties of
substance and of temperature, the utmost diversity of charac-
ter in point of tenacity, from firmness and brittleness, to the
most perfect pliability and ductility, must have belonged to
the assemblage in various parts.

‘Let us now suppose a rush to have taken place from below
upwards, of any of those bodies in a state of liquid fusion, which
on cooling have constituted all our unstratified substances, from
granite to whinstone inclusive, and that this fluid was ur-
ged by an irresistible force ; the consequence must be, that the
stratified mass would yield in various modes. Such beds as
were in a frangible state, would yield by the formation of rents,
and the others, by having their substance forced through and
partly dragged upwards. Into these rents and openings the un-
stratified matter in.fusion would enter, and would proceed up-
wards more or less, according to its fusibility. Whinstone, the
most fusible of the set, would flow the farthest, and would even
perhaps arrive at the surface, and there discharge itself in the
open air as a real lava, or, breaking through the bottom of a
deep sea, might constitute a submarine lava, like one of
those observed in Iceland by Sir Georce Mackenzie,
which, with the characteristics of a lava, have their cavities
studded with calcareous spar*. When I met with this ob-

_ Vor. VII. Loy ML. servation

* M. ve Luc, in his Elementary Treatise on Geology, p. 365. art. 311. has
undertaken to shew, that my experiments with compression are not applicable
to Dr Hurron’s hypothesis. ‘‘ When calcareous substances,” (he says, p. 365.)
«© are calcined in open air, the fixed air which is produced immediately escapes,

iG and

90 ON THE CONVOLUTIONS OF STRATA,

servation in Sir Grorce Macxenztie’s work, it recalled to
me what I had seen in Sicily, where the Cyclopian Islands, at
. the

“ and it continues to form until the substance is deprived of its ingredients ; but
“¢ when a solid body prevents its escape, the particles first formed acquire a de-
‘* gree of condensation proportional to the resistance which they experience,
“* and they oppose in their turn the same resistance to the formation of other
“© particles. Under such circumstances, therefore, if the heat be increased, it
“* produces other combinations of the fixed air with the calcareous earth, as in
‘© the experiments of Sir James Hatt. But, under water, which the particles
** of that gass can easily penetrate, in which, collecting in bubbles, they will
‘ rise rapidly, on account of their inferior specific gravity, there can be no im-
‘* pediment to their formation, any more than that of the aqueous vapour in wa-
*‘ ter, under the pressure of the atmosphere, when the heat is sufficiently in-
“ tense.”

When M. ve Lwvce says, that in my experiments a solid body preventing the
escape of the fixed air, “ the particles first formed acquire a degree of condensa-
** tion proportional to the resistance which they experience,” he must conceive,
that during the first application of heat, some fixed air has separated from the
lime, and has accumulated in the cavity left in the barrels. But if he will look
again into my paper, he will find that I had foreseen this inconvenience, and
had guarded against it; that being under the necessity of leaving some cavity,
in order to allow for the liquid expansion of the fusible metal, I introduced some
water into the barrel, which assuming the gaseous form, and reacting with great
power, before the heat had risen to the calcining point, effectually prevented the
separation of any fixed air. And the same thing would happen at the bottom of
a sea that was deep enough. In some of my experiments, made with a compres-
sing force equal to 171 atmospheres, equal to 5693 feet, or about a mile of sea,
the carbonate bore the heat of melting gold without calcination, and entered in-
to fusion. Now, it is obvious, that the same result must take place at the bottom
‘of a sea of this depth, and that a shell lying on its bottom, if met by a lava
whose heat was equal to that of melting gold, would enter into fusion, and no
fixed air would be separated in the form of gas. M. pe Luc’s objection, there-
fore, which is founded on the levity of the substance in that gaseous form, must
fall to the ground.

In those experiments which I have made, with a compressing force applied by
means of a known and regulated weight, the carbonate has been placed exactly

in

AND THEIR MEETING WITH GRANITE. Ol

the foot of Mount Etna, are possessed of that same character.
M. Dotomrev considers these and others as having been
covered by the sea.

Other unstratified substances would atta, in a liquid
state, to positions less and less elevated, as they were more
and more refractory; and the granite would be the soonest
congealed, being the least fusible of the whole set. In
any of these cases, when the opening above was stopt by
congelation, the force from below being irresistibly power-
ful, the liquid, as we have said, must have found room for it-
self among the strata. ‘This must have been done in one of
two modes.

Either, Ist, when the strata were in a hard and inflexible
state, in which case, the liquid must have forced itself be-
tween stratum and stratum, by flowing horizontally among
them, by which means an arrangement would be produced,
similar to that of great part of the group in this neighbour-
hood, consisting of Arthur’s Seat and Salisbury Craigs, as well
seen from the south-west, where thick beds of uniform basal-
tic matter, emanating on both sides from the vast massive
block in the middle, which rises highest of any, are interposed
between thin beds of freestone, lying parallel to each other,
and inclined to the horizon at an angle of about thirty de-
grees.

Or, 2dly, where the strata were soft and pliable, and pos-
sessed of considerable toughness. In this case, they would
yield on both sides, so as to allow the vein to become wider

M2 and

in the predicament ascribed to it by Dr Hurron, when exposed to the same heat
under a sea whose pressure is equal to that force.

The fusions, then, which have taken place in my experiments, confirm Dr
Hurton’s theory, in so far as it depends upon the action of heat on limestone.

92 ON THE CONVOLUTIONS OF STRATA,

and wider to an indefinite extent, producing a solid unstrati-
fied mass. At the same time, they must have made room for
that yielding, partly by heaving up the superincumbent mass,
and partly by propagating the motion horizontally along their
own beds; which last motion will be opposed by their friction
and inertia. _We should then have three forces more or less
opposed to each other ; the force of elevation of the liquid, the
superincumbent weight, and the friction of the strata. The
consequence would be, that the strata, to a certain limited ex-
tent, would be thrust horizontally ; and so far as that action
reached, would be placed in the exact. predicament of the
pieces of cloth in the old experiment, or of the clay in that be-
fore us, (figs. 4. and 6. Plate1V.) We have every reason to ex-
pect, then, that our experiments have been a faithful repre-
sentation of what would happen in a similar case in nature.
And the results we have obtained, bearing an exact resem-
blance to the peculiar forms of the strata of killas, seem to
justify that conclusion. If we suppose two such invasions of
matter in fusion, to rise parallel to each other, and both un-
der the circumstances above described, their influence exerted
in parallel, though opposite directions, would conspire, and
the space between them would be still more completely con-
voluted than where one action alone took place; or would be
carried to a greater extent, than merely the double of one of
them. Were the neighbouring veins inclined at any angle to-
wards each other, the amount of the effect produced, and the
situation of the axes of convolution, would-be difficult to cal-
culate; but it is certain, that their effects would still conspire.
The complication would be still farther increased along with
the amount of the action, if a third vertical burst of liquid
matter occurred, so as to enclose a district of the stratified
mass within a triangle. We are not possessed of data by

which

AND THEIR MEETING WITH GRANITE. 08

which the extent of such a triangle may be limited. It seems
clear, however, that the greater the superincumbent mass, and
the deeper the bed of ductile strata, provided that the force
from below were sufficiently powerful, the more extensive
would be this influence. And the influence of such a force
upon a mass which had, by previous actions, acquired a
simple curvature, will account for any deviation from that
simplicity. By acting upon a set of beds previously rendered
vertical in part, it might thus produce convolutions having a
vertical axis, as at Gun’s Green.

Let us now suppose, that, after the strata had cooled to such
a pitch as to lose their pliability, a fresh quantity of matter in
liquid fusion was impelled against them; the whole penetra-
tion would. now be effected, by rents traversing the convolu-
tions in all directions, and the liquid stone would flow into
them, the temperature of the strata not having yet fallen so
much as to occasion its immediate consolidation. Some of
these rents might penetrate the mass in directions horizontal
or nearly so ; and these, swelling by the infusion of liquid from
below, would form great unstratified masses, and contribute
powerfully to the general elevation.

All the junctions of stratified with unstratified matter,
which took place during this second stage, would possess a dif-
ferent character from that in the first. In the first, the axes
of convolution would of course be parallel to the neighbouring
boundary, between the two substances ; whereas, in the second
case, no such parallelism need be looked for, since the liquid
stone would flow in rents, and along surfaces which were pro-
duced by the laceration of a frangible mass, in which the axes
of convolution would act no part. .

According to this view, as all the substances concerned
must have lain very deep at the time of the first operation,
and as the mass by which this powerful horizontal thrust was

performed,

04 ON THE CONVOLUTIONS OF STRATA,

performed, must have been of great bulk and consequent soli-
dity, it seems probable, that the convoluted mass, together
with the matter in a liquid state which it had received after
its consolidation, would, upon a subsequent application of the
elevating cause, be more easily raised than the solid unstrati-
fied mass, by whose swellings the convolutions were first ef-
fected.

It is natural, then, to expect, that in the various rents and.
agitations which these masses have evidently undergone, the
original mover of the convolution, and the scenes of its meet-
ing with the stratified mass, may very frequently have been
left in the deep abyss. In an account which I am now pre-
paring to lay before the Society, of circumstances relating to
the revolutions of the earth’s surface, I shall have occasion
to state a fact, which seems to prove, that the particular mass
of killas of which we have been speaking, has undergone one
palpable revolution of this sort, by which the mass in its im-
mediate neighbourhood has been left at a considerable distance
below it. I must hope, however, that on some occasions, scenes
exhibiting the junction of the prime mover with the strata, and
in which the axes of convolution shall be found parallel to
that junction, may hereafter be discovered, in situations raised
up, and well exposed to view; and I recommend this as an
object of great interest to geological observers.

Our attention is naturally turned in this case to Granite, as
far surpassing in importance every other species of unstrati- —
fied body ; and I have little doubt that it has in fact been the
agent of these conyolutions. I have not, however, been able
to discover any case in which it has performed this function.
All the junctions which I have seen belong decidedly to the se-
cond class mentioned, and bear marks of an infusion of the li-
quid granite into hard and brittle strata; and the peculiar

junction

AND THEIR MEETING WITH GRANITE. 95

junction we have in view, if it does occur at the surface, will
most probably be found where. granite meets with gneiss or
mica-slate, not where it meets with killas*., I have no scrupie,
however, in presenting these speculations to the Society, al-
though I cannot produce direct evidence in support of them,
because I trust that the conjecture is sufficiently plausible to
merit some attention; and, above all, because it may be the
means of giving rise to much interesting observation, in a de-
partment hitherto overlooked, or in which, for want of any
connected system, the observations of travellers have been
lost.
It will be an object of consequence, that future travellers
should attend to this circumstance in the Alps, where a very
long ridge of granite is bordered on both sides by strata. The
ideas just stated, not having occurred to me till long after I
had left that country, I can form no judgment with respect to
what inferences may be drawn from the state of facts which
are there to be seen. It is certain, that the strata of the Alps
are very much convoluted, as mentioned in various places by
M. pr Saussure; but whether these forms could reasonably

be

* Gwyetss is found to pass by insensible degrees into granite; that is, speci-
mens of every conceivable intermediate step have been found. We may then
conceive one stage more advanced towards granite than the rest, in which all
character of the original stratification is removed, and the mass may have be-
come wholly crystalline, but in which the peculiarity of each stratum may still
have left a trace of its character, in the quality of the granite thus produced
from it. This seems to explain the nature of a great part of the internal ridge
of the Alps, which is possessed, as Saussure mentions, of a stratified character.
This mass may, again, be traversed from within by granite in higher heat, and
in a state of complete liquidity, which would be more ready than the mass first
described, to penetrate into the neighbouring masses. Accordingly, Saussure
observes, that those veins, and other masses which, project from the central _
ridge, and penetrate farthest into the neighbouring strata, are devoid of that
stratified character.

96 ON THE CONVOLUTIONS OF STRATA,

be ascribed to the elevation of the central granitic ridge, or
whether its arrival at its present place has been connected
with their formation, does not appear from any of the facts
which I have read an account of, or recollect to have seen.
It is probable that the point will not be decided, till that
country is visited by a person previously aware of the theore-
tical views which we have been considering.

A case of such convolutions is mentioned by M. pe
SaussuRE, at a spot which I remember well, the cas-
cade called the Nant d’Arpenaz, on the road to the Gla-
ciers of Chamouni. The strata there consist of limestone,
and are bent in such a manner, as to have struck that
valuable observer with the utmost astonishment; yet, in
our view, they may easily be accounted for by a lateral
thrust. In reasoning upon this subject, he finds himself for-
ced to contemplate the possibility of those convolutions ha- —
ving been the work of subterraneous forces, occasioned by in-
ternal fire ; but he abandons the idea almost as soon as he has
formed it, from the reflection that this mountain, and its
neighbourhood, shew no indications of the action of fire. Af-
ter a good deal of argument, he at last (though with seeming
reluctance), submits to the idea, that these great results
may have been the work of crystallization; the insufficiency
of which reasoning, Mr PLAYFAIR, in his Illustrations,
art. 207. has clearly pointed out.

Since this paper was read in the Society, I have met w ith
a very interesting account of a set of rocks in Argyleshire,
whose position and arrangement greatly resemble those which
I have been describing, and among which, one fact occurs
which seems well worthy of notice. . (This account is contain-
ed in the Edinburgh Encyclopedia, under the article Ar-
GYLESHIRE, and was written by Mr ArcuiBpatp Camp-

BELL,

AND THEIR MEETING WITH GRANITE. 97

BELL, whose recent death is much to be lamented). The
strata there described occupy a great extent of coast, near-
ly forty miles; they consist of strata of slate and limestone,
sometimes alternating, and seem to belong to the class of
killas. Their convolutions are less elevated and less abrupt
than those we have been describing, but in all other respects
exactly resemble them. One circumstance is mentioned by
the author as a simple fact, and without view to theory, but
which seems, in a striking manner, to accord with what we
have endeavoured to establish. ‘ Where the strata (he says)
consist chiefly of limestone, with few, or very thin stra-
“‘ ta of slate intervening between them, the thickness of a
stratum is frequently five or six times greater at the sum-
‘‘ mit of the wave, and at the hollow where it begins ascend-
ing to form the next wave, than at the intermediate point,
“‘ where the contrary flexure takes place.”

[ recollect no such difference as to thickness among our
strata; but the circumstance might be expected, upon our theo-
ry, to take place, when the beds acted upon by the horizontal
thrust were not only flexible and tough like cloth, but also
ductile, and capable of being elongated by pressure. For
supposing the thrust to have continued, after the folds had, to
a certain extent, been accomplished, it is evident, that the ho-
rizontal pressure acting in some degree at right angles to the
beds, where the contrary flexures took place, and of course
where their position was most erect, would tend to elongate
and thin them at those places, and would have a contrary ef-
fect, if any, at the summit and hollow of each arch, where the
stratum for a short space occupies an horizontal position,
This unexpected fact tends then, I conceive, in a striking
manner, to confirm our theory.

Vor. VIL. N When

98 ON THE CONVOLUTIONS OF STRATA,

WueEN we undertake to account for the convolutions of the
killas, by the forcible invasion of granite, one material point is
to show, contrary to the opinion entertained as yet, I believe,
by all geologists but those of the Huttonian school, that gra-
nite has been the latest formed of the two. The scenes in
Galloway, where these substances meet, prove this, I conceive,
beyond dispute; but they prove it over much in one point of
view, since they show the arrival of the granite at its present
place, to have been posterior, not only to the formation of the
strata of killas, but also to their convolutions when in a state
of softness, and to their subsequent consolidation. It must,
therefore, be admitted, that this mechanical effect cannot have
been produced by the particular granite there exhibited ; but
the circumstances which the junction presents to view, autho-
rise us to believe, that another granitic mass, acting in a for-
mer period, with the same powers, but when the killas was in
a soft state, has been the agent of these convolutions. It be-
comes, therefore, of great importance in this inquiry, to make
a clear statement of the mode in which the introduction of the
granite into its present place has been effected in this authen-
tic instance.

In that view, I shall ask permission to lay before ‘hie Socie-
ty, the details of some observations, which, in general terms, .
mentioned in a former communication.

In the year 1790, I read an account in this Society of my
observations on one of those granitic masses which reaches
from Loch Ken to the valley of Palnure, a short abstract of
which has been published in the History of the Society at
that period. It is there stated, that I had traced the junction
of this mass with the neighbouring rock, in a complete circuit
of it, which I made in company with the Honourable Tuomas

Dove as

AND THEIR MEETING WITH GRANITE. 99

Dovetas (now Earl of Selkirk), and that in “ all this extent,
‘« where the junction of the granite with the schistus was vi-
“ sible, veins of the former, from fifty yards to the tenth of
** an inch in width, were to be seen, running into the latter,
“* and pervading it in all directions, so as to put it beyond all
© doubt, that the granite of these veins, and consequently of
“the great body itself, which I observed forming with the
‘‘ veins one continued and uninterrupted mass, must have
“© flowed in a soft or liquid state into its present position.”

I have since, on many occasions, visited the same place,
and every fresh observation has confirmed my first impression,
and has served more and more to convince me, that the gra-
nite is posterior in formation to the killas, and has flowed into
its present position from below upwards, in a liquid state,
whilst the stratified mass was hard, or at least sufficiently so
as to break with sharp angles, and to allow the liquid granite
to mould itself upon its fractures.

I observed every circumstance that sad ot be expected 1 in
such a case. I saw the granite meeting the strata in every
possible angle. In one case, which occurs in the bed of the
river, at the High Bridge of Dee, I saw the bounding surface
of the granite dipping at an angle of 45 degrees from the
centre of the granitic mass, and the strata lying upon it, in
what (in the Wernerian language) is called a conformable posi-
tion to the granite, and corresponding exactly to what they
have held out as the mode in which the granite always meets
the strata.

The Hill of Lauren, which occupies the south-west of Loch
Ken (on the side of the granitic mass, nearly opposite to the
spot last mentioned) presents a junction of these bodies,
whose character is as completely different as could well be
conceived. At the southern extremity of the ridge, the junc-
tion is well seen, characterised by large features. The strata

N 2 are

100 ON THE CONVOLUTIONS OF STRATA,

are here nearly vertical, stretching from north to south. The
line of junction, which occurs on the face of the hill, towards
its summit, cuts the strata at various angles, sometimes nearly
at right angles; and the strata thus abutting endwise against
the granite, the two substances are, as it were, spliced into
each other. The granite enters among the strata in several
large dikes or veins, which at first are a hundred yards in

wideness, but which rapidly taper away to a small breadth.
Along the whole line of junction, from this point north-
ward to the burgh of New Galloway, at a distance perhaps of
two miles, a scene of almost perpetual interest presents itself,
being a repeated display of the penetration of the stratified
mass by the granite; and the rock being but thinly covered
with soil, these circumstances come frequently into view, and
particularly at the spots known by the name of Sight Knoll,
and the Hog Knoll. In 1788, I had seen an instance of ‘a
dike penetrating the strata, and distinctly emanating from the
mass of granite, in such a manner as to convince me that it
constituted with that mass one uninterrupted and identical
substance. On my return in 1807, when the subject had ac-
quired a peculiar degree of interest, in consequence of the dis-
cussions carried on in this Society, the progress of vegetation
had been such as to conceal it entirely ; but being well con-
vinced of the reality of its existence, I determined to recover
it, and employed several workmen to clear away the earth and
vegetable matter from the most interesting spots. At various
distances, within fifteen or twenty yards from the main gra-
nitic mass, several masses of granite, or portions of veins,
made their appearance, which I conceived to be emanations
from the great mass, although their junction with it was con-
cealed. I was anxious to trace some of these to their source ;
and after the labour of several days, I at last succeeded with
one

AND THEIR MEETING WITH GRANITE. 101

one of them, though I cannot tell whether or not this was the
same which we saw in 1788. Having in this instance traced
the communication between the vein and the main mass, [I al-
most exclusively devoted my attention to it, and, I trust, not
fruitlessly. Besides exhibiting by a drawing, (Plate V.), the
appearances of this very interesting spot, which is called the
Windy Shoulder, I procured a more expressive representa-
tion of it in the form of a model, which now lies before
us *,

The Windy Shoulder is situated nearly opposite to the
point on the other side of the loch, at which the Shirmers
Burn enters it; the entry bearing from it E..10N. by true
bearings. ©

The strata, which continue here in a vertical position, meet
the granite on the surface at an angle of about 45 degrees.
The dike runs for about twenty-three or twenty-four feet be-
tween two of the strata; it then starts across them, and re-
sumes nearly its first direction, which it pursues for a consi-
derable distance more; making in all ninety feet from the
granite. |

I was at the greatest pains to examine the circumstances at-
tending the exit of the vein. The earth and vegetation were
carefully removed. Some parts of the surface of the rock
were dressed by a mason, and a powerful temporary polish was
given to that surface by water dashed upon it. All these pre-
cautions tended to confirm the identity and continuity of the
two rocks, which appeared more and more conspicuously after
every fresh exertion that was made to remove the influence of
external actions. 3
. Dr Several

* I have also presented one of these models to the Geological Society of
London, |

102 ON THE CONVOLUTIONS OF STRATA,

Several small veins were found to cross from the dike to
the main mass, having an identity of substance throughout.
That which is represented in the model, incloses a triangle of
killas, whose sides are seven feet by five; the strata being
here moved by a small shift. Many other smaller veins oc-
curred of the same kind, and in the same position, which have
been omitted as too minute. The dike, near its exit, also ex-
hibits a fme example of another most important and instruc-
tive circumstance in geology. The granite actually contains
a mass of the stratified body included in its substance, and
surrounded on all sides with granite.

In the immediate neighbourhood of the granite, to the dis-
tance of a foot or two, and not more, the stratified matter has
in many instances assumed a highly micaceous character, so
as to deserve the name of Mica-slate, and perhaps of Gneiss.

Every thing seems to indicate that those dikes, which ap-
pear on this hill in such abundance, and which have been
shewn in this case to be continuations of the same mass, have
come from below; and this opinion seems to be strengthened
by the fact, that on the north-west side of the same Windy
Shoulder, the granite at the junction seems to dip under the
killas. From the shape of the ground, sinking rapidly below
the line of junction, I expected easily to reach the granite, by
blowing up with gunpowder the killas at some point beneath
this line. The first blast did not succeed ; but a second, near
the junction, was very effectual. It rent the mass at right
angles with the junction, by which the granite is seen actually
to dip under the killas, as at first supposed, with an irregular
line. |

The surface being dressed at the emergence of one of the
small veins from the great mass, the following curious fact
presented itself To the distance of about three inches with-

in

AND THEIR MEETING WITH GRANITE. 103

in the junction, the progress of the granite vein was visible
through the outer part of the granitic mass ; the substance of
which last was there in a confused and undefined state : far-
ther in, the vein spread wider, and in the space of a few inches
more, was quite lost in the general mass. I account for this
by supposing, that the granite near the junction being partly
cooled, and partly contaminated chemically by the contact of
the strata, is rendered less liquid than elsewhere, and that a
quantity of more thoroughly liquid matter occasionally and
subsequently forces its way through this barrier, and through
the contiguous substances.

_ We have thus a representation in miniature of one of those
events which I conceive to have happened on a large scale in
the formation of that mass, which, in its present elevated si-
tuation, constitutes the body of our island. One portion of
liquid granite, forcing its way among the strata of killas, then
lying low and flat at the bottom of the sea, and in a state of
softness and pliability from semifusion, has, by its swelling,
pressed them into a convoluted shape, and has taken its station
among them. By the progress of cooling, this whole assem-
blage, both stratified and unstratified, has become susceptible
of laceration, and has been rent by subsequent forces acting
from below. A fresh stream of liquid granite has penetr iil
into the rents so formed, and has’ swelled and spread among
the convoluted and broken killas, so as frequently to occupy
an extent of many miles, constituting one of our external gra~
nitic masses. But this last-mentioned invasion, though doubt-
ess producing a comparative elevation, has still, I conceive,
taken place at the bottom of a deep sea, where our sandstone
strata have since been deposited, on the rock both of killas
and of granite; and where the fragments composing that
sandstone have undergone the i Nene heat by which they

have

104 ON THE CONVOLUTIONS OF STRATA,

have been converted into stone. The whole assemblage of
granite, killas and sandstone, having been raised into the posi-
tion which they now occupy, by revolutions of a still posterior
date.

The present order of things may thus be accounted for, by
a set of progressive steps of elevation, without the necessity
of supposing, everywhere, an interposed submersion. Not
that I am disposed to deny the occasional occurrence of such
submersions ; which may naturally be expected to have taken
place, in consequence of the voids, which could not fail to be
produced by so many undoubted elevations.

The circumstances thus stated are different, as may be ob-
served, on the Hill of Lauren, from those of the junction on
the bed of the Water of Dee, as described above ; but such
differences are perfectly consistent with our view of a liquid
forcing its way among a set of beds previously consolidated
and indurated.

The conformable junction at the Water of Dee, is the only
one which, being ambiguous, does not contradict the Werne-
rian view of the general system; a view that is completely ex-
cluded by the perturbed junction at Lauren. Now, both of
these junctions are consistent with the Huttonian theory, ac-
cording to which, a diversity of this sort was to be expected
in such circumstances. It is very obvious, that the substance of
a vein must be of newer formation than the rock through which
the vein passes ; and it is no less obvious, that where the angu-
lar fragments of one substance are contained in another, the
substance thus contained must be the older of the two. In
these observations, we have seen that two veins of granite,
which penetrate the killas, do constitute one continuous mass
with the great body of granite which lies below, and are of
course of contemporaneous formation with it. The conclu-

sion,

AND THEIR MEETING WITH GRANITE. 105

sion, then, is irresistible, that the granitic mass of Lauren is
posterior in formation to the killas which lies above it. This
admits of no other rational solution, but by supposing, as Dr
Huron has done, that the granite, in a liquid state, has flow-
ed in its present position, and that emanations from that li-
quid penetrating into the rents of the strata, have formed the
veins.

The same general facts which have been observed with re-
spect to the granite of Lauren, and the district of which it
makes a part, occur also in the other two granitic masses of
Galloway, as I have found by a particular examination of their
junctions with the strata.

I was convinced of this as to the mass which crosses Loch
Doon, by a circuit which I made of that mass in 1807, accom-
panied by Mr Jarprve of this Society. In the island upon
which the Castle of Doon stands, a fine example occurs of an-+
gular fragments of killas, included in the granitic mass near
the junction. The dressing which this stone has received
from the hand of nature, renders this very conspicuous, as I
shall have occasion soon more particularly to state to this So-
ciety.

I have at different times, though not with the same regula-
rity, examined various places, where the third granitic mass
in Galloway, of which the Mountain of Criffel makes part,
meets the surrounding strata ; and I have seen dikes of granite
near the junction, and other circumstances leading to the
same conclusion, particularly on the sea-shore, at a place
known by the name of the Needle’s Eye, which approaches to
the granite boundary; and also on the side of Criffel, which
lies directly opposite.

_ According to a rough computation, asta of these three
granitic masses occupies a ee of about six miles by four.

Vou. VII. O _ Their

10 6 ON THE CONVOLUTIONS OF STRATA,

Their positions, and bounding lines, which are very irregular,
are laid down, as nearly as we could guess, in the map of
the stewartry of Kirkcudbright, now ‘on the table. There is
good reason, I conceive, to suppose, that all granitic masses
are related in a similar manner to the neighbouring strata,
where such strata are found penetrated by granitic veins.
Such veins were first observed, I believe, by M. pve Saus-
suRE, in the Valoisine, and also at Lyons and Semur. Dr
Hurron examined them with great care in Glentilt, in
Arran, and in other parts of Scotland, and upon these obser-
vations founded his bold and original theory with respect to
granite. Mr Prayram has not failed to make ample use of
those which he has more recently discovered at St Michael’s
Mount in Cornwall. All. the appearances which I have wit-
nessed in Galloway, as to the relative situation of granite, and
the contiguous rock, accord with the doctrine of Dr Hurroy,
and tend, I conceive, to confirm his views.

It might be rash to extend universally to all granite those
conclusions which have been established by particular ocbser-
vations ; yet as no instance warranting a contrary inference
has occurred since the subject began to be inquired into,
enough seems to have been done to contradict the generality
of that leading maxim of the Wernerian doctrine, that the
order of position which rocks maintain with respect to the
centre of the earth, denotes the order of formation.

It is an important circumstance to observe, that the sub-
stance whose formation is thus proved to be prior to that of
the. granite of Galloway, is the killas, or grauwacke of the
German school, which, holding only a middle station among
stratified bodies, as to antiquity, is considered, according to
their doctrines, or of formation long subsequent to that of
any kind of granite. The quality of this. stratified mass,

from

AND THEIR MEETING WITH GRANITE. 107

from one side of the island to the other, seems to be uniform
throughout, except in the immediate neighbourhood, or con-
tact of the granite, where it assumes a micaceous character,
approaching to the nature of gneiss or mica-slate. This fur-
nishes a most notable indication of the action of heat ; since
the granite, by its local intensity, has performed the very ef-
fect which Dr Huron ascribes to the general heat below,
as acting upon the lower beds, and converting them into
gneiss. | pie ep:

Another cireumstance of importance is, that at the Rae
Quarry in Peeblesshire, nearly in the middle of this mass of
killas or grauwacke, a bed of limestone occurs, interstratified
with the killas, and of course coeval with it, which bed con-
tains shells in abundance. Now, as this mass of killas has
been proved to be of older formation than the granite of Gal-
loway, it is obvious that granite is here found to be of a for-
mation posterior to the existence of living animals.

The relative age of granite and of sandstone has not been
decided in any case that I have had occasion to observe, and
is a point of considerable importance in geology. Nothing
seems as yet to prove, that granite may not have flowed up
against a stratified mass, possessing, in some of its parts, the
properties of sandstone ; I conceive, however, that these pro-
perties will nowhere be found to belong to that part of the
stratified mass which lies close to the granite. For we have
seen, on the Lauren, that killas near the junction has been
changed into gneiss or mica-slate by the heat of the granite,
as we conceive ; and there is still stronger reason for believing,
that a similar change would take place on sandstone in the
same circumstances. We ought, therefore, to find, that while
a remote portion of the stratified mass retains the properties
of sandstone, that which lies but at a little distance from the

O02 granite,

108 ON THE CONVOLUTIONS OF STRATA, &c.

granite, has been converted into gneiss or mica-slate, or at
least into killas; and this view is confirmed by the circum-
stance, that no example has been produced of granite veins
traversing sandstone.

I expect, then, that granite and sandstone will not be found
to occur in immediate contact, unless where the latter has
been deposited upon the former. In the junction which is
seen in the bed of the river near Jedburgh, and in that at the
Siccar point, on the coast of Berwickshire, we see that the
sandstone has evidently been deposited in the state of loose
sand, on killas then existing as a hard and shivered rock.
We may easily conceive, that sandstone has been deposited
in a similar manner on the granite of second invasion ; and
that, in a similar manner, it has been consolidated and ele-
vated.

I have not met with an example of this; but such may be
looked for, and will be interesting in geology. I have just
learnt from a young friend, member of this Society, who has
spent a few days in the course of this year at the Cape of
Good Hope, that upon the side of the Table Mountain, a junc-
tion occurs of granite with killas, and that, higher up on the
hill, the same granite actually meets with sandstone. I hope
soon to have the means of laying before this Society the details
- of these observations..

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Il Remarks on the Transition Rocks of WERNER:

By Tomas Axian, Esa. F.R.S. Eprn.

,
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[Read Feb. 17. 1812.].

| Lrnoucu we have many writers on geological subjects,’
whose works are distinguished by ingenuity of doctrine,
and novelty of opinion, and, among them, some who have :
made advances towards arrangement ; it was reserved to the
celebrated Werner, to introduce means, by which rocks might
be described with some degree of precision. Many ingenious
theories were invented, to account for their formation ; but .
little or no attention was paid, to the acquirement of an ac-
curate knowledge, either of their composition, or their relative
position in nature ; although these certainly appear to be the -
bases, on which such speculative opinions ought to be found-.
ed.
But while we acknowledge these obligations to the Professor
of Freyberg, we cannot extend our unqualified approbation to
the systematic arrangement he has introduced. It was not to be
| expected, that the labours of one individual, who, from peculiar
circumstances, was confined within certain limits *, were suffi-
| cient
* In Werner's Preface to his Theory of Veins, he states, that his limited for-

tune, and the nature of his present situation, prevented him from travelling into
more distant countries. ANpErson’s Translation, xxi,

110 REMARKS ON THE

cient to attain perfection ; nor could it reasonably be supposed,
. that any-district, however extensive, should be so singularly:
favoured, as to contain all the variety of facts, that occur in
other parts of the world, from which deductions are to be
drawn, and elucidations afforded, investing phenomena. with
characters which they do not present elsewhere.

In forming his arrangement, Werner may have exhausted
the means he’ possessed ; te therefore, ought not to be reproach-
ed, for although his conclusions are more general, than are war-
ranted by the circumscribed field to which he was confined,
yet he has formed a groundwork, on which the labours of fu-
ture geologists may rear a system, more capable of affording sa-
tisfaction.

It is greatly to be wished, that arrangements of this kind
were less dictated by theory. The pupils of the Wernerian
School have been peculiarly fettered, by an ideal necessi-
ty of supporting the principles of their master ; but the blend-
ing of theory with description, is an error common to all spe-
culative geologists ; the support of preconceived opinions being
very generally the principal object in view.

Hence we find, that collections of those facts which are
supposed favourable to certain doctrines, have been eagerly
pursued, and others, equally interesting in themselves, entire-
ly overlooked ; while that minute detail, which is alone capa-
ble of placing the student in a situation to draw conclusions of
his own, has been totally neglected.

The part of the Wernerian System, which it is my inten-
tion to notice at present, is the class of rocks termed Tran-
sition. After stating the grounds on which this distinction
has been established, and the particular rocks of which the
series is composed, with their extent and importance, I shall

endeavour

TRANSITION ROCKS. 1ITI

endeavour to shew, that those which constitute its principal
members, are similar in different districts ; and, finally, that
they are of an older date than Granite, which maintains the first
place in point of priority in the system of WERNEr.

It is well known, that one of the principal arguments Uaoial
forward by Dr Hurton, is drawn from the penetration of the
stratified rocks, by veins extending from the mass of granite,
which he considered as affording a decisive proof, of the subse-
quent formation of that rock. It must not, therefore, be sup-
posed, that I aim at any thing original in the above assertion,
or that I even wish to limit the term Alpine Schistus, as ap-
plied by that ingenious philosopher; there can be no doubt;
that, under this name, he ineluded both the Primitive and
Transition stratified rocks of Werner ; but in his time no di
stinction had been drawn between them: it is only Jater disco=
veries that have imposed the necessity of! more specific lan-
guage, which may at once account for that want of precision
by which his writings are so much obscured, and the deficien-
cy of mineralogical iinawlédad, with which he has been so fre-.
quently dunerod

Werner, in the construction of his systematic: arrangement,
shinighst that he perceived grounds for considering all rocks,
from Granite down to Clay-slate, as bearing marks of having
been deposited from the original chaotic fluid, in a certain de-
terminate order. In them no detritus, or anything like organised
nature, was to be observed; and to this point every rock re-
mained exactly in the same state, in which it was at the period
when it first acquired solidity.. To these alone the title of
Primitive was attached.

In the rocks immediately following, of which Limestone is
said to be the first, he remarked an essential difference; the
limestone not only abounded in organic remains, but other

members

112 | REMARKS ON THE

members of the series were composed of fragments, which
must have existed previously in a different state: hence he
inferred, that these rocks were formed at a subsequent period,
which, from their constituent parts, he concluded, must have
been after the creation of living animals, and nearly at the
time when the earth passed from its chaotic to its habitable
state * ; and on these grounds he distinguished this class by the
name of Transition. |

To this another class succeeded, also presenting new and di-
stinct characters, one of the most remarkable of which is posi-
tion. They are never found conformable with the transition
rocks; while these present an uneven or serrated outline, ei-
ther from the natural contortions of the strata, or the bro-
ken edges of the highly inclined beds ; the rocks which suc-
ceed, fill up the inequalities, and assume an horizontal posi-
tion. To them he gave the name of Floetz rocks.

Thus the system is divided into three great classes, the Pri-
mitive, Transition, and Fleetz.

Although the Transition has been known in this country as
a separate class, only within a few years, yet it occupies a lar-
ger superficial extent in these islands, than any other rock-for-
mation. But before I proceed to trace its limits, it may be
proper to explain what is understood by the Transition Se-
ries.

In doing this, and, indeed, in whatever else I have stated,
with respect to the Wernerian Geognosy, I beg to be under-
stood as having taken it from that work, which I consider as
containing the most authentic account of the system taught at
Freyberg; I mean the third volume of Professor Jamrson’s
Mineralogy. As WERNER has published no account of it himself,
it is only from the works of his pupils that we can become ac-
quainted with his system. After the intense labour which has

been

* Jameson’s Mineralogy, vol. ur. p. 146.

TRANSITION ROCKS. 118

been bestowed on bringing it forward *, it cannot be supposed
to contain any errors, according to the strict notions of Wer-
NER; and if his pupils find it necessary to introduce any ma-
- terial alterations, and so to mould it, as to suit their own subse-
quent observations, it will no longer be the system of that phi-
losopher,—which the arguments in the present paper are alone.
intended to meet.

The Transition Series is caftipeeed of Limestone, Grauwacke,
and Grauwacke-slate, Trap and Flinty-slate. TetiestOds Is pla-
ced first, as being the oldest member, and is said to rest im-
mediately on the newer clay-slate t. Of this we have no in-
stance which I am acquainted.with in Scotland, where, indeed,
transition-limestone may be considered as rather of rare occur-
rence. Grauwacke, and grauwacke-slate are with us the princi-
pal members. The first of these is a stone usually of a bluish
colour, passing into grey, and sometimes greyish-red ; it is
composed of fragments, often of considerable size, but some-
times so minute as to be scarcely distinguishable; these
fragments are quartz, clay-slate, flinty-slate, and occasionally
jasper, which are agglutinated by a basis of clay-slate, through
which minute particles of mica are also sometimes dispersed.

Grauwacke-slate differs from the fine-grained grauwacke on-
ly in its minute stratification, and fissile character ; it bears so
strong a resemblance to clay-slate in hand-specimens, that even
an experienced eye cannot distinguish it; in the rock it is not
so easily mistaken: it usually alternates with grauwacke, and
is often remarkably contorted. Both substances are traversed
by quartz veins, which are sometimes of enormous dimen-
sions, but generally very minute and abundant.

Vou. VII. be The

* Werner, “ after the most arduous and long-continued investigation, con-
ducted with the most consummate address, discovered the general structure of
the crust of the globe,” &c. Jamuson’s Mineralogy, vol. m1. p. 42.

+ Jameson’s Mineralogy, vol. 11. p. 147.

114 REMARKS ON THE

The only limestones of this class that I know of, are three :
First, that of Rae Quarry, near Crook in Peeblesshire, where
it is interstratified with grauwacke, and contains abundance of
shells. The second is that of Cumberland, on the Jakes of
Windermere and Coniston, which also contains organised bo-
dies. The third is the Plymouth limestone, which, according
to the account of Professor PLayrair, corroborated by Dr Brr-
GER, is also transition-limestone; and in it Mr Prayram
states, that he found a petrified shell*, I have not my-
self visited the spot, but it is of consequence to observe,
that the limestones of all these different districts exhibit traces
of organic remains. The other transition-rocks, are Trap and
Flinty-slate +; but I have had no opportunity of observing either
of them in their natural position. Such, according to Werner,
is the extent of the Transition series ; but it does not compre-
hend all the rocks which occur in some of the transition dis-
tricts, particularly that of Cumberland, although, with little ex-
ception, it is adapted to the south of Scotland, in a very remark-
able manner.

I may now notice the extent of country occupied by rocks
of this description ; but such is our limited acquaintance even
with our own island, that it can be done only in an imperfect
manner. We know too little of the north of Scotland, to be
able to say, what rocks occur beyond the Moray Frith; but it
is by no means improbable, that when these regions have been
more fully examined, the transition series will be found among
them. Indeed I have learnt from Dr Maccutzocu, that it oc-
curs in great abundance in the north.

I

* Jllustrations of the Huttonian Theory, p. 165.

+ I suspect both these abound in the mountains of Cumberland, from speci-
mens I have picked up among the loose fragments.

TRANSITION ROCKS. 115

-{ am inclined to consider, that it occupies a large propor-
tion of Forfarshire ; and if I be correct in an observation made
on the banks of Loch Katrine several years ago, the transition
rocks extend in that direction. I have likewise found traces
of them on the right bank of the Clyde, near Dalnotter Hill in
Dunbartonshire. But the transition country we are best ac-
quainted with is that of the south of Scotland, which stretches
entirely across the island.

On the one side, it begins near the boundary between Kast
Lothian and Berwickshire, and continues along the coast, to a
little beyond the river Tweed. Extending a line from the first,
to a point on the west coast, between Girvan and Ballantrae;
and from the second, another which shall pass, by Langholm, to
a point between Annan and: Carlisle, we shall find nearly the
whole of the intermediate space to be Transition, excepting

where granite comes in, and some partial deposites of later
strata, which occupy the lower parts of the valleys of Nith,

Annan, &c.
~The mountainous ists of Cumberland, Westmoreland,
and the north of Lancashire, which is divided from the Transi-
tion of the south of Scotland only by a small proportion of pa-
rallel strata*, belongs to the same, at least we know of
none other with which it can be classed, although it contains a
variety of rocks, which cannot be referred to any in the series
of WERNER.

Adjoining to this, in the western part of Yorkshire, the
same rocks occur: it is on these that the limestone of Ingle-
a. and Whernside rests. To this succeeds the extensive

BZ ows district

* This term has been applied to distinguish the sandstone strata, and in that
sense I now use it; it is objectionable, however; for all stratified rocks present
the phenomena of parallelism, consequently, without qualification, this term af-
fords no distinction.

116 REMARKS ON THE

district of parallel strata, including the coal-fields of Warring-
ton and Wigan, and the great alluvial deposite of Cheshire.
These bring us to the neighbourhood of the Welch mountains,
which I believe are all of the same nature, some specimens ha-
ving been given me by a member of this Society, taken from
the summit of Snowden. Grauwacke, according to Mr Arkin,
makes its appearance at Church Stretton in Shropshire *;
_and near Hay, on the border of Hereford, I observed it my-
self. |

A great part of Somerset, and, finally, the whole of Devon
and Cornwall, again excepting the granite, and a small por-
tion of serpentine, and some other rocks, are all composed of
Transition strata. Thus, by extending a line almost due south,
from Berwick to the English Channel, we shall find a large
proportion of the country to the west composed of Transition
rocks ; while, so far as I know, none occurs to the east of it ; al-
though it is probable, that at Mount Sorrel in Leicestershire,
some of the same series may be found.

We are still less acquainted with the precise limits of its ex-
tent in Ireland: we know, however, that it occupies the coast,
from Belfast Lough to the mountains of Morne, which are of
granite ; it also extends westward as far as Monaghan, and
probably much beyond that point. From what Mr Werp
states, in his account of Killarney, it appears to be the princi-
pal rock of the Kerry mountains, and I know it occurs in great
abundance in the county of Cork.

Hence, even with the little information we possess respect-
ing its exact limits, we have enough to know, that the. transi-
tion rocks form a very large proportion of the superficial ex-
tent of Great Britain and Ireland, and also comprehend the
principal mining districts.

Having

* Geological Transactions, vol. 1. p. 212.

TRANSITION ROCKS. 117

‘Having thus imperfectly chalked out the boundaries, or ra-
ther localities of the transition districts in these islands, I shall
endeayour to shew that some of the rocks of Cornwall are
grauwacke, in all respects similar to some of the south of Scot-
land ; and if strata may be compared to the leaves of a book, a
few decided and indisputable specimens are sufficient to cha-
racterise a district.

It was in consequence of some observations during a tour
through Cornwall and Devon last summer, that I was led to
suspect this class stood in a very different relation in point of
period, with respect to granite, from that which I had hitherto
conceived ; greater experience, or perhaps sufficient attention
to the writings of Dr Hurron, might have pointed out this before. .
Had I looked more attentively into his description of the granite
district of Galloway, and at the same time attended to the na-
ture of the stratified rock of which that country is principally,
composed, this fact would not have been new to me now.
There were other circumstances, however, which severally
contributed to prevent me from supposing that grauwacke:
could occur in this position.

First, The unlimited use to which Dr Hurton applied the:
term Alpine Schistus, left us quite uncertain with respect to
the species of rock he meant: secondly, the alteration induced
on grauwacke,near its junction with granite,—a circumstance so-
strikingly exemplified in Galloway, that I own it deceived my-
self; and, lastly, the assertion I have so often heard repeated
by the Wernerian geognosts, that granite veins never occurred
excepting in rocks formed of the same constituents, alluding to.
gneiss and mica-slate.

_ Before I visited Cornwall, I knew that granite abounded in
the Stannaries, and that tin and wolfram, metals which are con-
sidered nearly of the highest antiquity, were there common.

productions..

118 REMARKS ON THE

productions. I therefore expected to meet with a perfect epi-
tome of the Wernerian System, containing the usual series of
primitive rocks, descending from granite, through gneiss, mica-
slate, and clay-slate, with all the et ceteras of serpentines, traps
and porphyries ; but in this I was mistaken.

On my approach to Exeter through Somerset, I first obser-
ved the transition strata. between Bridgewater and Taunton ;
(Nos. 1. &2.*) and from thence traced them, more or less distinct-
ly, till I crossed the river Teign, which bounds Dartmore on
the east. Thus far great part of the country is very flat, some of
it extremely hilly as a road, but none of it mountainous. The
transition strata are by no means continuous, and in many
places appear only in small projections above the surface.

On the right bank of the Teign, the road winds up the side
of a steep hill; and where the rock is cut, there is a consider-
able display of strata, having all the external appearance of
grauwacke. On examining it, I found some of the strata
coarser than others ; but, in general, the grain was extremely
fine, (Nos. 5,6, 7.) the texture solid and compact, the colour
very dark-grey : it was very tough under the hammer, it broke
with a smooth, and somewhat conchoidal fracture, and did
not split into the thin lamine of the grauwacke-slate.
This appearance puzzled me at first; the rock presented
all the external characters of grauwacke, and yet internal-
ly it was different. [ had not proceeded many paces, how-
ever, when I came upon Granite, (No. 8.) the proximity
of which, as before mentioned, is always marked by a
very material alteration in the consistence of the adjoin-
ing rock. This alteration, I observe, was not unnoticed by
Dr Bercer, in his interesting paper t on the physical structure

of

__* The numbers refer to the Appendix, at the end of this paper.
+ Geological Transactions, vol. 1. p. 112.

i]

TRANSITION ROCKS. 119

of Devon and Cornwall. In mentioning grauwacke, which he
distinguishes from grauwacke-slate only by its compactness,
he says, “ It is found higher up than the grauwacke-slate, it
“ may be supposed to have been precipitated more slowly, and
“ under less powerful pressure ; whereby the mass has been al-
“ lowed to contract, and to assume a kind of crystallization. It
“ rests immediately on granite.” ‘The conclusions he draws are
different from mine; but from the above quotation it appears,
that the circumstance I observed at Teign Bridge is usual in

similar situations all over Cornwall.
Near St Austle, on the road leading to Carclaze mine, I

found grauwacke, (No. 23.) in my opinion extremely well cha-
racterised ; also on the road to Cambourn, not far from Dol-
coath, (No. 31.); likewise on the shore near Penzance (No.
42, 43.). Here it is also fine-grained, and tough under the
hammer, and at no great distance from granite. Near Oak-
hampton, I found it along with grauwacke-slate, in the most
unequivocal state, (No. 57.) ; and on the shores of the Bristol —
Channel, near Ilfracombe, the rocks are all of the same mate-
rial *, |

Here, on the beach, to the west of the town, I spent some
hours the evening before I crossed to Swansea ; and found no-
thing among the rocks, to lead me for a moment to question,
that they were wholly composed of grauwacke. Indeed I even.
remarked some of the contortions which are so common in this
rock. Next morning, however, when walking down to the
boat, under a point where a small battery is built, I found on

the

* The specimens alluded to, were examined by the gentlemen present when
this paper was read, who considered those from the road leading to Carclaze

mine, and from near Oakhampton, as Grauwacke; and those from the vicinity of
Penzance as Greenstone.

120 REMARKS ON THE

the trodden surface of the rock, an appearance very similar to

mica-slate, for which. substance it might readily be mista-
ken, (No. 61, 62.), but this resemblance appears to be owing
to the friction of the feet, and the action of the weather, on a
variety of grauwacke, containing an unusual proportion of
mica.

By casting an eye over the map of Cornwall, it will be ob-
served, that the above specimens are selected from the
most remote corners of the peninsula. On examination, I
think they will be found sufficiently similar to the Grauwacke
of Werner, to be entitled to be classed along with that rock.
Dr Bercer, in his paper on the physical structure of Cornwall,
gives them no other name, and if authority is to be qualified
by experience, the opinion of one who has traced the footsteps
of Saussure, and who has studied the geognosy of WerRNER
with the utmost enthusiasm, cannot fail to he received with re-
_ spect.

I have thus endeavoured to shew by the selection of spe-
cimens, and by the opinion of a very scientific observer, that
the stratified rock of Cornwall is grauwacke. It would be un-
candid, however, not to acknowledge, that the general texture
-of this rock was different from the grauwacke of the south of
Scotland ; it was more of the slaty variety, and frequently seem-
ed, from its smooth and soft feel, to contain a large proportion
of magnesian earth *.

I understand, in a course of lectures. now delivering, a very
material alteration has been proposed upon the Wernerian Sys-

tem,

* Since I read this paper, I have had occasion to pass through the transition
country of Peeblesshire, &c. On former occasions, I was in the habit of search-
ing ior characteristic specimens of the grauwacke ; I now looked for such as re-
sembled the killas of Cornwall, which I found in abundance, (Nos. 62, 63.).

TRANSITION ROCKS. 121

tem, in order to introduce thisrock in a position distinct, and very
distant from grauwacke. It appears to me much more simple
to suppose, that rocks of the same class, in different districts,
may present peculiar characters, than that the operations of
nature should have been so multiplied and complicated, as to
afford the endless distinctions which are thus required. | In-
deed, I cannot help thinking, that if the Killas of Cornwall had
been sufficiently known, it would have excluded entirely the
introduction of that harsh-sounding German term Grauwacke.
Killas appears to me to be as proper a translation of that word
as Specular Iron-ore is of Eisen-Glanz, and I think may be
used with great propriety ; distinguishing Grauwacke and Grau-
wacke-slate, by Amorphous and Schistose Killas.

The only other rock of any importance in Cornwall is Gra-
nite, termed Grauen by the common people,—a name also given
to clay-porphyry, a substance found pretty frequently in large
veins, (Nos. 16, to 19, 28,48.) The shades of distinction chro-
nicled by the mineralogist, cannot be expected to attract the at-
tention of the miner, who knows but two rocks, grauen and kil-
las, throughout the Stannaries. It has been thought that a dis-
tinct rock was understood by the term Elvan ; but this is a mis-
take, elvan may sometimes be greenstone, but in general is
either killas or granite, and is so termed by the miner when he
finds the rock harder to work in one place than in another.

Before I entered Cornwall, I was led to believe that it
abounded in two kinds of granite, Primary and Secondary.
Never having had an opportunity of comparing them in situ,
I was anxious to do so here, and different localities were
pointed out to me; these I examined with care, but could
discover no grounds to justify any distinction. Dr BrrcEr
makes no mention of secondary granite; and another gentle-
man, whose opinion on this, as on most subjects, will be
received with the utmost deference, and who had the same ob-

Vor. VII. Q | ject

122 REMARKS ON THE

ject in view, during a visit made since I was there, informs me
that he could discover no distinction at all.

It is therefore of importance to ascertain whether the granite
of Cornwall be new or old; which will easily be done, by com-
paring the appearances it presents, with the descriptions of
these rocks as given in the Wernerian school; it is there
taught, that three formations of granite have been ascer-
tained.

The oldest is the basis or nucleus, round which ail other
rocks have been deposited. The second occurs only in veins,
traversing only the granite of the older formation. The third
rests on some of the older primitive rocks, in unconformable
and overlying position. From this description of its external
relations, it is evident that the granite of Cornwall can neither
be the second nor third. With respect to its internal structure,
we have the following definition: Granite is a granular aggre-
gated rock, composed of felspar, quartz, and mica. These al-
ternate from large to small, and even to very fine granular.
The large and coarse granular usually belong to the oldest ;
the small and fine granular to the newest granite formations.
Besides felspar, quartz and mica, other fossils sometimes occur
in it; of these, schorl is the most frequent, then garnet and
tinstone *.

At Penzance I observed some buildings constructed of a re-
markably fine-grained granite ; but this | nowhere saw in situ:
otherwise, from Teign Bridge, where I first set my foot on
granite, to the Land’s End, it is generally of that character
which entitles it to be ranked with the oldest variety, (Nos.
8, 21, 27, 34, 35, 54, 55.) In many places it has suffered to a
most wonderful extent by decomposition, but where it retains
its freshness, no granite can possibly be better characterised.

The

+ Jameson’s Mineralogy, vol. m1. p. 102, &e.

ee

TRANSITION ROCKS. 123

The specimens which I was able to bring away, and which
are now before the Society, are by no means adequate to con-
vey an idea of the coarse texture it sometimes presents. In
the granite of Dartmoor, the crystals of felspar are uncommon-
ly large, often four inches in length. I believe it was from
this neighbourhood that the flags of the footpath on Westmin-
ster Bridge were brought ; in these, crystals of felspar nearly as
large may be observed.

Granite countries usually present a bold and varied outline ;
but to this rule Corrwall is a most decided exception : its as-
pect is tame in the extreme, being comparatively flat,—a cir-
-eumstance visibly occasioned by the corroding operations of
time. Nowhere are the vestiges of degradation so remark-
able as here. The enormous deposites of tin in the different
stream-works, of which that of Carnon is perhaps the most ex-
tensive, clearly prove the destruction of surrounding moun-
tains. This tin, in the shape of rounded pebbles, formed a
stratum, of about a foot thick, under a deposite of granite-gra- |
vel and mud, together forming an overburthen of forty feet
thick, and occupying a valley of very great extent. The lodes
which furnished this tin must have existed above the level of the
deposite ; and from the quantity of metal deposited, they must
have occupied a large tract of country. Other monuments of this
general destruction may be found in the peaks which are seen
in every direction in the granite districts of Cornwall. These
are evidently the result of surrounding decomposition, and are
formed of huge masses of rock, apparently piled on each other,
with a regularity resembling masonry, and in all respects simi-
lar to the arrangement observable on the summit of every
mountain in Arran, where the traces of time are also deeply
furrowed.

Roach Rock, a binary compound of quartz and hornblend,
is another very remarkable instance of the same fact: this rock
is flat at the top, and being quite perpendicular on three sides,

Q2 : when

124 REMARKS ON THE

when viewed from the west, presents the appearance of a
square castellated building, which is rendered more conspicu-
ous, by being nearly of the same height as the tower of an ad-
joining church. There can be no doubt that this singular
rock, owes its present appearance to the operations of time on
the surrounding materials, which its peculiar composition has
enabled it to withstand.

The killas likewise presents marks of degradation, where the
country is composed of that rock. I noticed in some districts
the roads mended entirely with quartz, (No. 24.) ; the brilliant
white appearance of which, after a shower, had a very curious
effect. I could not comprehend by what industry the accu-
mulated heaps of this substance were obtained: at last I per-
ceived that they were gathered from the adjoining fields, and in
some places picked from the surface of a common, by means of
a hoe or mattock. That fragments of quartz should occur so
unmixed with any others, is only to be accounted for, by sup-
posing that they formed the quartz veins in the killas, which,
from superior tenacity, resisted decomposition, while the softer
parts of the: rock, yielding to the action of the weather, were
reduced and carried away.

We thus find, that the granite of Cornwall possesses the
characters ascribed by Werner to that of the highest antiquity.
Some inferences may likewise be drawn, in corroboration of its
title to be classed with rocks of this description, from the na-
ture of the metallic veins by which it is traversed.

In the German account of the relative ages of metals,
tin is the third, and wolfram the fourth in order of antiquity *.
If veins’containing these metals, be considered in other coun-
tries as indicative of rocks of the oldest primitive formation,
the same application must be made to those of Britain.

I may now ask, if this be not the Oldest Granite, where are
we to find it? as it appears to me impossible that any sub-
: stance
* Jameson’s Mineralogy, vol. 1. p. 275.

TRANSITION ROCKS. 125

stance can more decidedly concur with definition. In the Alps,
Dr Bercer must have learnt what primitive granite meant; yet
not a doubt escapes him, of the Cornish being any thing else.
Distinctions either do, or do not exist; if they do, character
must be attended to; if they do not, it is quite unnecessary to
add the terms Secondary and Tertiary to a substance posses-
sing every attribute of a primary variety, merely because the
structure of an adjoining rock does not accord with a specific
theory.

Grauwacke, or, as I shall in future call it, Killas, I have be-
fore noticed, is a rock composed of fragments more or less
comminuted, which must have existed in another state before
they assumed their present. arrangement. Along with the-
strata formed of these, beds of limestone are found, containing
indications of organic remains. ‘These are not confined solely
to the limestone, they occur also in the killas; a fact whic
may be witnessed at any time, either.in the neighbourhood of
Coniston *, or on the right bank of the Blackwater, a little. be- -
low Fermoy, in the county of Cork, (Nos. 66, 67.). The for-
mation of this class of rocks was therefore subsequent to.the
formation of living animals, whose existence is supposed to be
proved by the occurrence of organic remains in the composi-
tion of the rock..

In Cornwall, in Westmoreland, in Galloway,.and in the
counties of Down and Derry, this rock lies directly on. granite,
—a circumstance which we should at first sight be inclined to
consider as indicating its subsequent formation. This thought,
however, vanishes the moment we contemplate the veins of —
granite by which it is traversed. Of. these there are many ex-

amples; |

* Since I read this paper, I wrote to a friend at Coniston, requesting a. few
of these specimens, well characterised, might be sent me: some of which are de-.
posited, along with the rest, in the cabinet of the Society, (Nos. 64, 65.)

126 REMARKS ON THE

amples; but the most striking are at the Louran in Galloway,
and at St Michael’s Mount in Cornwall. .

It is many years since Sir James Hatt laid before this So-
ciety an account of his observations on the granite district of
Galloway, of which the Louran forms a part; and to the perse-
vering activity of that gentleman, we are indebted for the dis-
play of one of the most interesting exhibitions of granite veins
that exists. The peculiarities observable in Galloway, were first
pointed out to me by him; and as he has so lately favoured
the Society with a particular account of them, it leaves me no-
thing to say regarding that quarter.

At St Michael’s Mount, the shooting of the veins from the
great mass of granite, is also most strikingly exemplified.
They were here first noticed by Professor PLayrair, who com-
pares them, most aptly, to the ramifications of the vegetable
root * ; for, indeed, nothing can be more illustrative of the phe-
nomenon as it is here exhibited.

It is to be observed that granite veins, particularly when ex-
tremely minute, usually differ in texture from the mass to
which they belong. While the little peak of St Michael’s Mount
maintains a similarity of character with all the rest of the
Cornish granite, not only in point of internal structure, but
with respect to the tin and copper veins which traverse it, as
well as by the massive blocks, hewn by the corroding hand of
time, which ornament its summit; the veins that set off from
it, gradually become finer as they recede, but still preserve the
perfect character of the rock.

The importance deservedly attached by Dr Hurron to the
phenomena of granite veins, gave rise to a variety of hypothe-
ses among those who were inclined to consider this rock as
the original deposite, who have accounted for their formation
in different ways.

It

* Illustrations of the Huttonian Theory, p. 318.

TRANSITION ROCKS. 127

lt was first stated, that they were formed of newer granite,
and, if properly examined, would be found to cut the old gra-
nite as well as the rock which rested on it.

This opinion was-once very strenuously supported. in this
country ; but as facts would not bear it out, it was abandoned.
I find, however, in a recent publication, something similar to.
it maintained by Dr Luc, who asserts that the veins at St Mi-
chael’s Mount are not granite, but merely quartz, which tra--
verses the granite as well as the stratified rock. I cannot com-
prehend how De Luc could have been so much deceived at
this place ; as simple inspection of the smallest. specimen, will
prove that he was mistaken.

It was next said, that the veins in question were not true
veins, but such as are termed Cotemporaneous. To support
which, it was boldly asserted, that they never extended beyond.
the limits of such rocks as were composed of the same mate-
rials, gneiss and mica-slate.

I trust it is now distinctly shewn, that they do extend bes
yond these limits, and likewise that they traverse rocks from :
which, by no method of reasoning, it can be supposed that
they could possibly be formed by secretion.

The last opinion is that which has recently been brought
forward by Dr Bercer*. After describing the granite veins of
St Michael’s Mount, he proceeds to say, that they are simply
elevations on the plane of the granite existing previous to its
being covered by the stratified rock; that the spaces between
them were filled up as the grauwacke was deposited ; and hence
the abrasion of the surface, brought to light a section, which
has merely an appearance of veins.

_ Were the devotion of Dr Brrczr to his master less conspi-
cuous in his geological disquisitions, I should be inclined, on
the

* Transactions of the Geological Society, vol. 1. p. 147.

128 REMARKS ON THE

the above statement, to call his character as an observer in
question, having passed over in silence the detached masses
of killas, which he could not fail to observe included in the gra-
nite, and which the above hypothesis is as far from accounting
for as either of those mentioned before.

_ [have only a few specimens (Nos. 39, 40, 41.) to lay before
the Society from the veins of St Michael’s Mount; but they
are equally interesting and satisfactory. One, exhibits a por-
tion of the killas bounded on each side by granite; another, a
portion of two granite veins traversing killas; and the third a
mass of killas included in the granite.

Simple inspection is sufficient, in the first place, to shew
that the opinion of Dre Luc is groundles with respect to the
substance of these veins. One of the specimens also, contains
two small veins of quartz, which are of the kind called Cotem-
poraneous ; these keep the direction of the seams of the strati-
fied rock, and are cut off by the granite in the same line with-
out any interruption. |

To the opinion of Dr Brrcer they also offer some reply.
If the grauwacke had been deposited on the granite in the
way he supposes, it is natural to conclude, that it would
have been arranged in lines parallel to the sides of the
elevations, somewhat similar to the coating of bark on the
trunk of a tree: but in place of this, the seams of the killas are
set at an angle of about 30°, to the planes of intersection with
the granite ; consequently, if deposited from a supernatant
fluid, they have assumed a very different position from that
which either mechanical or crystalline influence would have
induced.

The hypothesis suggested to Dr Hurron by the appearance
of these veins, meets every difficulty: they conveyed to him
evidence of being derived from a source of the greatest vio-
lence ; and also that nothing but liquid matter injected from

below,

TRANSITION ROCKS. 129

below, could have created the disturbance among the stratified
rocks, so conspicuous when in contact with granite. As itis a
self-evident position, that a rock which is cut by a true vein,
must have existed in a solid state previous to the formation of
that vein; so is it equally obvious, that if the vein can be tra-
ced into an adjoining mass, of which it is found to be a part,
that mass must stand in the same relation, in point of period,
to the rock which contains the vein, as the vein itself does:
as also, that if pieces of one rock be found imbedded in
another, the including rock must have been of, subsequent
formation to the included... No theory, however, but that
of Dr Hurron can account for these appearances: to. no-
thing. but force can the position be attributed, which the
stratified rocks haye assumed in the vicinity of the unstratified;

and nothing but matter injected i in.a liquid state, could possi-
bly have formed the shoots which traverse from the great mass
of granite perforating the stratified rock, and at the same time
envelope detached fragments of that rock. As the idea of vio-
lence in these operations has been so frequently combated, I
cannot refrain from noticing here, a very striking mark of it I
met with at Coul in Ross-shire, when visiting Sir GxrorcE
Mackenzie. There the strata of gneiss are oie disturbed
by the invasion of granite veins: near which, on the outside
curvatures of some of them I perceived rents similar to what we
might expect on bending a flattened mass of clay, nearly de-
prived of moisture. I am fortunately enabled to present to
the Society specimens illustrative of this interesting fact (Nos.
68, 69.).

An the theory of Dr Hurroy, we find also some grounds to
account for the diminution of grain in the substance of the
veins. The same cause to which, in a former paper,, I at-
tributed the gradation in the texture of greenstone, may
be supposed. to have acted here.; It does not, however, ob-
Vou. VIL. R serve

130 REMARKS ON THE

serve an equal constancy, some veins of granite being as coarse-
grained as the mass to which they belong.

In a former part of this paper, I had occasion to notice an
alteration which appears to take place in the texture of killas,
when in the vicinity of granite. This circumstance was so re-
markable in Galloway, at the Louran and other places, that I
took the strata so situated, for mica-slate, although I had obser-
ved no line of separation between it and the killas ; I was for-
cibly struck with this, at the moment, but having then no time
to follow it up, I was obliged to leave the country without any
particular examination. It will be observed, by the specimens
from St Michael’s Mount, that the killas there assumes the ap-
pearance of fine-grained gneiss. At Wasseldale Crag, between
Kendal and Shap, I noticed a rock, in the immediate vicinity
of granite, quite similar; and I am told, that the texture of the
strata, near the granite of the mountains of Morne, is altoge-
ther the same.

This alteration is always of a gradual nature; and is so im-
perceptible, that it affords a good example of what might be
understood by the German term Passage, or transition from
one species to another ; this Passuge, even admitting the sub-

_stance altered, is of too limited a nature to constitute a distinct
and totally different rock. _

This alteration, if traced with attention, may lead to some
very important results ; but, without entering upon it at pre-
sent, I shall content myself with recommending it to the no-
tice of geologists, some of whom may consider it of too minute
a nature to deserve attention. They may, however, rest assu-
red, that it is only by an accurate examination, and a faithful
detail of such objects, that we can hope to arrive ultimately at
truth, the only solid basis of philosophic inquiry.

I may be accused of generalising too much in the foregoing

statement, on grounds so limited; it must be remembered,
however,

TRANSITION ROCKS. 131

however, that I have purposely confined myself to the exam-
ples of the relations which exist within my own knowledge,
between the Transition rocks and Granite. The same pheno-
mena are familiar, where gneiss and mica-slate come in contact
with that rock ; but as these strata are considered to be of a
very different age, the facts which I might have cited, had my
object been to prove the age of granite with respect to all
other rocks, were unnecessary, when my purpose was to point
out the relative ages of killas and granite.

From what I have said, I consider myself warranted in fi--
nishing this paper with the following conclusions :

The Killas of Cornwall belongs to the Transition series of
WERNER.

The Granite of Cornwall is possessed of every character by
which the Oldest varieties are distinguished.

That Granite, the nucleus round which Werner conceives
all other rocks were deposited, is in some cases actually of a
_ later date than the Transition series, which comprehends strata
containing shells; and that its subsequent formation is clearly
evinced by the appearances at St Michael’s Mount.

Hence, that the distinction of Transition rocks, is grounded.
on false conclusions.

And finally, That Werner must make very material altera-.
tions on his present system, if he wishes to accommodate it
to the phenomena so commonly presented in nature.

R2 APPENDIX.

GY

ently, tan wee

Barge eMac ey

eas -puwceintiy vem

oy bets a)
Peat ae
fo ove

rs ye ee Ts eee apie

crn

133

APPENDIX.

On a former occasion, I stated as my opinion, that all geolo-
gical papers ought to be accompanied with specimens of the
rocks of which they treated. This is a condition not always
to be complied with, unless the intention to write precedes the
examination, when a collection may purposely be made; but
when the idea suggests itself, after one is far removed. from
the district, it amounts nearly to an impossibility. In the pre-
sent instance, although I be possessed of all the specimens
necessary, they belong to a series which I formed for other
purposes. Mather, however, than mutilate this, I have
thought it better to present the whole to the Society, in
whose possession I shall have an opportunity of referring to
them at any time; and as they have signified their acceptance,
it is necessary to add to my paper, the following brief list of
the minerals I collected, which are marked and numbered, as
picked up on my route, commencing in Somersetshire, where
the transition rocks first make their appearance, and ending at
Ilfracombe, after traversing Devon and Cornwall in different
directions.

After leaving Bristol, on the road to Exeter, we traverse the
limestone ridge of Mendip; to the south of which, there is an
extensive plain, stretching to beyond Taunton, whose unifor-
mity is occasionally interrupted by small isolated hills, like
islands in a lake. These are probably formed of Transition

rocks,

Nos. I, & 2.

5,6, 7.

134 REMARKS ON THE

rocks, although on the plain itself, where the soil is laid
open, which is principally composed of limestone debris hori-
zontal strata of the same substance were exposed to view. Ap-
proaching Taunton, the road leads over some of these hills,
and here it was that I met with strata highly inclined, very
similar in colour and aspect to some varieties of sandstone, but
considerably more refractory under the hammer, indicating,

I suspect, the commencement of the Transition series.

VesicuLar Trap. I found this on the road near the house of
Sir Tuomas Actanp, a few miles north of Exeter. I saw
none of this in situ, though very commonly in the buildings
in and about Exeter.

On quitting Exeter for Moreton, the road is extremely hilly,
rising and descending over abrupt knolls almost all the
way ; these are principally formed of a soft decomposing
rock, in thin strata, breaking in rhomboidal fragments, and
very similar to the slaty clay of Werner.

After passing Teign Bridge, this substance assumes a greater
degree of consistence, and occurs in strata nearly vertical,
some of which are coarser in the grain than others. These
were extremely difficult to break, and presented a close
smooth fracture, approaching to conchoidal.

The Teign is the eastern boundary of Dartmoor, and, within a
few hundred yards, of it, and immediately beyond the strati-
fied rock last mentioned, Granite occurs, containing very
large crystals of felspar, which continues to within a short
distance of Tavistock, situated on the Tavy, which bounds ~
Dartmoor on the west side.

Here, as on the banks of the Teign, the. Killas rests upon the
Granite. At Wheal Friendship, a mine at that time under
the management of Mr Joun Taytor, (to whose intelligence
I am deeply indebted for a great share of the information I

obtained

10.

11.

12.

13.

i4.

18.

TRANSITION ROCKS. 135

obtained in the country), I selected the following speci-
mens, as illustrative of the Cornish terms, which certainly
afford the best explanation that can be given, of a language
entirely peculiar.

Killas, by comparison with the Grauwacke Slate of Frey-
berg, I find this to be quite as similar as any two speci-
mens from the same quarry could be expected to be.

Elvan, as pointed out at Wheal Friendship. This I took for
coarse-grained Grauwacke ; it was very difficult to break,
and a very small proportion of it exposed to view. I could
not, therefore, observe its connection with the surrounding
rocks ; but, from more minute examination, I suspect it may
belong to a bed of Greenstone.

. Capel, a veinstone or Salband, composed of Quartz penetra-

ted by Chlorite.

A Bunch of ore, is here exhibited by a portion of Copper-
pyrites, in a vein of Quartz, which represents the lode.
When found in this way in a mine, it is termed a Bunch of
Metal. i a |

A heave to the right, the Killas is here traversed in different
directions by Quartz veins; that marked A represents a
lode, intercepted and heaved to the right by B, a cross
course. When the lode is cut in a very oblique direction,
it is said to be caunted.

A Horse, when a lode is divided, and joins again, it is said
to take horse, and the included mass in this specimen, is
called the Horse of Killas, &c. |

A Squat, when the lode suddenly enlarges, it is called a
Squat; and the metal it contains a Squat of Ore.—By
means of this vocabulary, I very soon became familiar with
many of the commonest mining terms in the country.

In

Nos. 16. to 19.

20.

ai.

136 REMARKS ON THE

In order to form a junction between the Tavistock Canal
and the Tamer, it became necessary to drive a tunnel, for
a mile and a half, through a hill called Morwel Down, which
promises to be a source of interest to the geologist. In

forming this tunnel, several powerful veins of clay porphyry

have been penetrated, the substance of which is in some places
much disintegrated, in others firm and compact ; veins suppo-
sed to correspond have since been observed on the surface.

In the tunnel, the Clay Porphyry alternates several times with
the Killas, which is here of a light-grey colour, and a soft
friable texture.

In the course of this undertaking, two workable metallic veins
have been intersected, no traces of either had been found on
the summit of the hill, although diligently examined.

Passing the Tamer, we enter Cornwall, and at Gunnislake, is
a mine of Copper in Granite ; and a little beyond, at Drake-
walls, there is another of Tin, in Killas.

Tin-vein in Granitc, from Carelaze, near St Austle.

Killas found on the road from St Austle to Carclaze; this I
consider a very perfect specimen of Grauwacke.

Mass of white Quartz, of which the roads are formed.

Mixture of crystallised Quartz and Wolfram, covered with a
coating of Bitumen, found in Poldice mine near Redruth,
at the depth of 106 fathoms, in Granite.

Arsenical Pyrites, mixed with acicular, dark, greenish-grey
crystals, supposed to be actinolite, front sna S Shaft, a
branch of Wheal Unity.

Granite, Cairn Brae.

From a vein which traverses the north-east side of Cairn Brae:
on the spot it appeared to me to be Clay-Porphyry, i in hand

specimens it resembles fine-grained Granite.
Vein-stone.

Nos. 29:

30: +

31.

TRANSITION ROCKS. 137

Vein-stone of Quartz, impregnated with red Oxide ef Iron,
and containing white Steatite, from Tincroft.

From the high-read near Tincroft. This is a very tough rock,
and very fine-grained: it appears to be a variety of Green-
stone similar to NO. 10.

Killas, marked with dark-coloured spots, from the side of the
road to Cambourn, a little westward of the last.

Killas of a light-grey colour, from St Anns.

From Beacon Hill, a conglomerate formed of the debris of
Granite, very similar to some varieties of Sandstone.

Granite from the Land’s End.

Hornblend-Rock from Botallock, a curious, little, but valiiable
mine, on the north side of the Peninsula, near the ex-
tremity.

Cockle, massive Tourmaline, from the same place.

Specimens from the junction of the Granite and Killas, at St
Michael’s Mount.

From the shore near Penzance: these I consider to be Killas
of a very tough and compact variety, they are found very
near Granite, or some similar rock, which presented some-
thing so peculiar in the aspect, that I cannot help recom-
mending it to the attention of geologists.

Serpentines from the Lizard.

Hornblend-Rock, which forms the basis on which the light-
houses of the Lizard stand.

Clay-porphyry, near Trewithin.

Granite, with a vein of Tin, St Stephen’s.

Conglomerate of Quartz and Granular Talc, from the same
place.

Phosphate of Lime and crystallised Talc, in Granular Talc,
from Stoney Gwins.

Killas from a quarry between Bodmin, and the race-course of
that town. This substance is very soft, but well adapted

Vou. VII. Ss for

54, 55.
56.

57.

58.
59.

60, 61.

62, 63..

64, 65.
66, 67.
68, 69.

70.

138 REMARKS, &c,

for building, from the peculiar facility with which it is quar-
ried ; the stratification being horizontal, and the cross rents
perpendicular, and so regular, the quarry presents a very
symmetrical appearance.

Granite, coarse-grained, near Bodmin.

Fine-grained Killas, near Launcestown.

About sevén miles from Launcestown, on the road to Oak-
hampton, I found a quarry containing schistose and amor-
phous Killas interstratified, the last of which I believe to be
as perfect Grauwacke as any in the district of Lammer-
muir.

Greenstone, Hatherleigh.

Variety of Trap from Cleave.

Killas from Ilfracombe, alluded to in page 119.

Specimens quoted, but not from the same country.

Fine-grained Grauwacke, from Peeblesshire, in all respects.

similar to the Killas of Cornwall. Note, p. 120.
Shells in Killas, from Coniston. Note, p. 125.
Same from Fermoy, county of Cork, p. 125.
Gneiss from Coul, p. 129. :
Transition Limestone from Rae Quarry, containing shells,
p-. 113.

IV.

Sy ae

Te —————

IV. On the Revolutions of the Earth’s Surface. By Sir James
Hatt, Bart. Pr. R.S. Ev. & F.R.S. Lonp.

PART L

[ Read March 16. 1812. ]

I, are never more disposed to give credit to a philoso-
phical system, than when we meet with a case of its
successful application, unknown to the author, or containing
circumstances which he had not taken into account when he:
formed that system.
~The facts brought forward in the following paper, which,
according to my view of the subject, clearly indicate the
operation of immense torrents, can be accounted for, I think,
in a very satisfactory manner, by the Huttonian Theory, and
consequently afford some very powerful arguments in support
of it.
But such was by no means the view taken of this subject by
Dr Hurrown himself, or by Mr Prayrar, who, since his death,
82 has

140 ‘ ON THE REVOLUTIONS

has so ably illustrated and maintained his geological opinions.
These gentlemen have expressed themselves, on all occasions,
in a manner peculiarly hostile to the employment of such

torrents as geological agents, believing that all the phenomena

may be traced to the influence of diurnal causes only.

I have no hesitation in declaring my hearty concurrence in
what I consider as the essence of the Huttonian Theory ; I
mean as to all that relates to the influence of internal heat in
the formation of our rocks and mountains: But I could never
help differing from Dr Hurton, as to the particular mode in
which he conceived our continents to have risen from the bot-
tom of the sea, by a motion so gentle, as to leave no trace
of the event, and so as to have had no share in producing the
present state of the Earth’s surface.

_ At an early period of life, while I imbibed from the delight-
ful conversation of my worthy friend Dr Hurron, the spirit of
his geological views, I retained my attachment to opinions
suggested by M. pvr Saussure’s observations, which, at a
still earlier period, I had acquired in the Alps, and which
had. been: rivetted in my mind by the sight of the pheno-
mena from which they have. been inferred. The facts also
observed in the Russian empire, and broyght forward. by
Professor Patuas, relative. to the productions. of the tropics,
which are found upon the banks of the Frozen Sea, appeared
to me of sufficient force to justify his belief, that, at some re-
mote period, a torrent of water had swept across the conti-
nent of Asia. I have, therefore, been always disposed to com-
- bine the doctrines of Hurron with those professed by the gen-
tlemen just named, relative to marine inundations ; and a num-
ber of facts which I have observed in this country, will con-
tribute, I hope, to throw. some additional light upon this, diffi-
cult subject.

Before

A

OF THE EARTH'S SURFACE. 14]

Before mentioning my own observations, I beg leave to lay
before the Society the state in which [ found the question.
The central ridge of the Alps, of which Mont Blanc is the
principal mountain, consists, as is well known, of Granite.
Nearly parallel to it, and at a distance of fifty-four miles to the
north-west (by Sir Grorce Suucksurcn’s measurement) lies
the mountainous ridge of Jura, fifty or sixty miles in length,
composed entirely of calcareous matter. Between these two
ridges are interposed the valley and lake of Geneva, and other
valleys and inferior hills. The native place of the granite is
confined to the centtal ridge; but over the surface just de-
scribed, innumerable detached granitic blocks are very irregu-
larly scattered, which have originated, as we must presume,
in that central ridge, and have been transported. to their pre-
sent position by some mechanical power.

Upon the southern side of the Baltic, a multitude of similar |
blocks are found, also scattered irregularly over a sandy di-
strict, of which a particular and detailed account is given in
M. pe Luvc’s Geological Travels, vol. i.

The origin and history of such blocks, which occur in yva-
rious other places, have given rise to considerable discussion ;
and the question. is inseparably connected with other points
of magnitude in geology,—such as the formation of valleys
and lakes, and the distribution and arrangement of various
beds of clay and gravel, and of all the loose and alluvial as-
semblages which occur under various forms in all parts of the
globe, and constitute its most valuable districts in point of fer-.
BUY,

M. ve Saussure ascribes the transportation of the granitic
ioe lcs on the Alps to the action of an immense torrent of wa-
ter, or Debacle, as he terms it, which at some remote period,
flowing over the summit of the Alps, had carried these blocks
along with it.

Dr

142 ON THE REVOLUTIONS

Dr Hurron and Mr Prayrar, as I have already said, deny
the necessity of introducing such an agent, since the circum-
stances, as they conceive, might have been produced by the
usual action of rivers. But this simple view seems to be ex-
cluded, when we consider both the magnitude and the posi-
tions of these blocks. Their size, in some cases, amounts, as
in the valley of Monetier upon Saleve, to 1200 cubic feet, and
in the case of those on the Coteau de Boisy, to 2250, and even
to 10,296 cubic feet, which is the measure of the block called
Pierre & Martin.

To move a mass of granite of even fifty or sixty cubic feet,
and to carry it a few yards, would require the utmost efforts of
the Rhone or the Arve, as they flow near Geneva, in their
highest floods, but that such blocks could be conveyed by one
of them along its whole course, is contrary, I conceive, to all
experience, and still more when we consider that these rivers
are divided at their source from beneath the Glaciers into for-
ty ot fifty small streams. Yet from the Glaciers, these blocks
must have come ; and when we take into account the magni-
tude of some of the granitic masses, it is clear that the task is
beyond the power of any river that flows on the surface of the
earth ; nay, it seems more than water, under any predicament,
could accomplish, and more than could be expected from the
Debacle itself, however extravagant its magnitude may appear:
but we shall again return to the subject, and shew in what
manner this difficulty may be explained.

These stones do not lie merely in the beds of rivers, but oc-
cur all over the country, and on the summits of mountains,
where rivers could least be conceived to have flowed ; nor are
they confined to that side of the country, or to the side of the
lake of Geneva which lies next the Alps; for we find them in
particular on the face of Jura, which fronts the central ridge

and

— i ee ee

OF THE EARTH’S SURFACE. 143

and the lake, at an elevation of 2000 feet above the latter. A
set of low hills also intervene, which occasionally hide that cen-
tral ridge from the view ; and it is principally where the snowy
summits are visible from the face of Jura, by means of some
depression in these intervening hills, that we find those travel-
led masses; as I remember well to have witnessed, at some of
the places which Saussure has pointed out, where, in higl:
situations, on the face of Jura, I rode through great assem-
blages of granitic blocks, three or four feet in diameter.

The force of this fact is admitted, but an attempt is made *,
even under that admission, to refer the whole to diurnal ac-
tions, by supposing, that from the spot where these blocks lie,
up to the summit of Mont Blanc, one continued solid plane
has ascended, along which, on a declivity computed at one in
thirty, these blocks may have been hurried by a stream of wa-
ter ; and that subsequently, in the course of ages, all the inter-
vening mass had been washed away, so as to reduce the coun-
try to its present situation. But this hypothesis removes the
difficulty of the intervening valleys only ; for the transporta-
tion in this case would be scarcely less difficult than it would
be to Geneva, as matters stand at this day ;—and a circum-

stance occurs, founded upon the observations of Sir Grorcr

SHUCKBURGH, which seems entirely to Laie this hypothe-
sis.

According to his measurement and scale, as given in the
Philosophical Transactions, vol. Ixvii. the height of Mont Blanc
is 14,432 feet above the lake, and the distance in a straight line
from Jura to Mont Blanc, I find, by his scale, to be nearly fif-
ty-four miles, and 2000 feet is the height at which these gra-
nite blocks occur on Jura. The slope, therefore, along which
these blocks must have descended, would be nearly that of one

. ; in

* Zilustrations, art. 345, page 385.

144 ON THE REVOLUTIONS

in twenty-three. But without inquiring whether or not this
declivity would be sufficient for the purpose, it is of conse-
quence to attend to another circumstance pointed out in these
measurements. The line above which snow lies perpetually,
during all summer, is there noted, and lies by the scale at
7500 feet perpendicular below the summit of Mont Blane. It
is easy, then, to calculate to what horizontal distance from the
centre of the ridge, this limit of perpetual snow would extend,
and we thus find it to be 32 miles *. But Saussure has found
the junction of the granite with the surrounding strata at the
Buet, and by the same scale, I find the distance of this moun-
tain from Mont Blanc is about 10 miles. It is obvious, then,
that in the supposed situation of the Alps, in which the gra-
nitic

* Let AD be Jura, and BC Mont-Blanc. Let D be the place on Jura where
the blocks lie; the line DC will be the outline of the supposed surface. Let
AB be drawn horizontally at the level of the surface of the lake, and DE at a
level 2000 feet higher, meeting BC in E. We have then AB = DE = 54 miles.
= 285120 feet ; and CE = CB— EB = 14432 — 2000 = 12432 feet. The mea-
sure of this declivity along CD may therefore be easily obtained. Thus,
CE: ED: : 12432 feet : 285120::1:22.9, nearly one in twenty-three. Mr

Puayvrair states it at one in thirty ; but he has reckoned to the summit of Jura ;
whereas the blocks under consideration lie at some distance below that summit.

Let CF be equal to 7500 feet, and let FG be drawn horizontally; then
G will be the lowest point of perpetual snow upon the supposed surface.
The ‘horizontal distance of G from the centre will thus be obtained,
CE:CF:: ED: FG, or 12432: 7500: : 54 miles : 324 miles. Let H be the ex-
treme point of the granitic mass at the Buet, and let HK be drawn vertically;
the point K will.denote the limit of the granite upon the supposed surface.

OF THM EARTH’S SURFACE. 145

nitic mass could not be conceived to extend farther than it
now does from the middle, that the whole granitic surface must
not only have been buried in everlasting snow, but that the ex-
tent of this snow must have been three times that of the gra-
nite. Now there is every reason to suppose, since the tempe-
rature diminishes as the height increases, that within this up-
per third, the temperature has never, in the hottest day in sum-
mer, reached so high as 32°; that is to say, that water has ne-
ver there existed in a liquid form. We cannot, then, conceive
any block, however small, to have been conveyed from thence
by means of water, acting by the usual diurnal laws,

M. ve Luc admits the reality of M, pr Saussurz’s debacle,
and accounts for it in the same manner; but he does not
ascribe to it, either in Germany or in the Alps, the transportation
of the granitic blocks, the presence of which he accounts for verv
differently. He supposes that these blocks have nowhere migra-
ted along the surface, but have been ejected from below, at the
_ places where they now lie. This ejection he produces by a
very extraordinary hypothesis *, founded entirely on gratui-
tous suppositions, and which affords no plausible solution of
the difficulty, by which we might be tempted to adopt it.

_ M. ve Luc mentions a theory formed by Mr Wrens, a Pro-
fessor of Berlin, to account for the same blocks. He embraces
a belief which seems to have been in considerable favour, that
the level of the Baltic Sea has been sinking for ages past, and

he extends his belief of the same change taking place in the
- Vou. VII. fy whole

* He supposes, that below the firm crust of the earth, then lying horizontal-
ly at the bottom of the sea, a set of caverns once existed, filled with peculiar elas-
tic fluids. That at a certain period, this crust breaking to pieces, fell with great
violence into these caverns, and drove out the elastic fluids contained in them
with such impetuosity, that the blocks of granite under consideration, which then
constituted portions of the lower part of the crust, were forced upwards into the
air, and fell back into their present position.

146 ON THE REVOLUTIONS

whole of the North Sea. His idea is, that a change has been
gradually going forward in the position of the centre of gravity of
the earth, which has been moving to the southward, and that an
equivalent rise is experienced in the southern hemisphere.
That when the North Sea stood at its highest level, these gra-
nitic blocks had been transported across the Baltic, by means.
of the winds, on floats of ice, and settling in their present pla-
ces, had been left by the retiring waters.

M. ve Luc, in a very satisfactory manner, in my opinion, re-
futes one essential part of this system, by shewing, from the
form of the new lands, and from other circumstances, that no
change in level whatever has taken place on the surface of that
sea for many ages back, and, indeed, ever since the surround-
ing country has possessed its present form. As to the other
part of his system, which relates to the transportation of these
blocks by means of ice, we shall soon have occasion to resume
its consideration. *

Besides the consequences resulting from these particular
phenomena, there are other material branches of Dr Hurrten’s
theory connected with the same views, which in my opinion
require to be carefully revised. The theory which he has ad-
vanced respecting the formation of valleys, by mere diurnal
actions, appears to me liable to great objections, and I cannot
help agreeing with M. pve Lue, in much that he has urged
against Mr Prayrarr on this pot. I also concur with my
friend Sir Georcr Mackenzig, in some general views, sug-
gested to him by the aspect of certain rocks in Iceland, and
in rejecting the slow operations of the reggiiene > ( Travels
in Iceland, p. 39.)

The difficulty is peculiarly great where a ley occupies the’
bottom of the valley, and is very conspicuous in the case of the
Jake of Geneva lately mentioned. For, granting all that has

heen

@F THE EARTH'S SURFACE. 147

been advanced in support of the diurnal formation of the val-
‘ey in which this lake lies, granting that it has been excavated
by the diurnal actions, since these granitic blocks were deposi-
ted upon Mount Jura; it still remains to be explained, how
the lake of Geneva itself was formed, the depth of which
amounts in some places (Saussure, art. 44.) to 950 feet. Now,
as has very fairly been stated, this lake is constantly receiving
all the spoils of the district which lies above it, called the Val-
lais, yet delivers nothing at Geneva, situated below it,
but pure water. It is evident, then, that every known diur-
nal action tends to fill up this lake, and none to excavate it.
This is therefore admitted by Mr Prayraar, to be a case “ in
“ which hypothetical reasonings are warranted by the strictest
“* rules of philosophical investigation, and where we must
“ therefore have recourse to an agent that is invisible.” /Ju-
strations of the Huttonian Theory, p. 366.

This acknowledged difficulty seems calculated to entitle the
following speculations to a patient hearing from this gentle-
- man; and he has already, in another part of the same work,
expressed himself with regard to them, and other kindred opi-
nions, in a manner highly encouraging to discussion, and which
affords one of the most striking examples of candour that has
ever occurred.

“ These arguments,” Mr Prayrair says, (referring to those
he had just been stating) art. 367. page 412. “ appear to me
“ conclusive against the necessity of supposing the action of
sudden and irregular causes on the surface of the earth. In
this, however, perhaps I am deceived, neither Patias nor
“ Saussure, nor Do.omiev, nor any author who has espoused
“ the hypothesis of such causes, has explained his notions
“ with any precision; on the contrary, they have all spoken
* with such reserve and mystery, as seems to betray the weak-

, T2 “ ness,

ao

4

hal

$

al

148 ON THE REVOLUTIONS.

“ ness, but may have concealed the strength of their cause. I
have, therefore, been combating an enemy that was in some
respects unknown, and I may have supposed him dislodged,
only because I could not find his strong holds.”

The charge of obscurity here brought forward, is very appli-
cable to the diluvian system of Saussure and Dr Luc, in what
regards the origin of the torrent, or the disposal of the water
after it had overwhelmed the land. The same charge seems
not, however, to: apply to the suggestion of Professor Patuas,
who, in an early work, entitled, Observations sur la Formation
des Montagnes, first published in 1777, has very, explicitly a-
scribed the inundation by which he conceives the continent of
Asia to have been overwhelmed, to the action of volcanoes ri-
sing in the Indian Sea, and forming the Moluccas, the Philip-
pines, and other islands, known or supposed to be volcanic.

It must be admitted, that such an event may occasion-
ally have happened. But the occurrence of similar catastrophes
may be inferred in a, manner still more general and unequivocal,
from those Plutonic * revolutions the reality of which has been
established by Dr Hurron’s observations. According to his
system, all our strata once lay at the bottom of the sea, and
have been raised into their present situation by the subterra-
nean and submarine exertions of heat, similar to that which ap-
pears externally in the volcanoes. And the angular fractures.
exhibited by these beds on many occasions, prove that this
elevation. was performed in such cases when the mass was in
a hard state. It is obvious, then, that the same principle:
which I lately attempted to apply (page 87. of this volume) to
the volcanic phenomena, as exhibited in the Atrio del Cavallo,
will apply to those Plutonic revolutions ; and we are authori-

sed

6

* T need scarcely say, that by the term Plutonic, I mean to characterize that.
geological system in which the principal agent is heat acting under Compression.

OF THE EARTH'S SURFACE. 149

sed on these principles to expect, that the liquid substances
of basalt and of granite, in their progress through the renis
of our strata, have been exposed to congelation, like the
lava in the rents of Mount Vesuvius; that their progress
has been arrested, and the protruding energy accumulated in a
similar manner, till it acquired sufficient power to break
through that obstacle, or through some other opposed to it ;
and it is manifest, however gradual and uniform the propelling
force may have been previous to its accumulation, that the ul-
timate laceration must have been performed, by a sudden and
violent motion, producing an earthquake at the surface, and
‘thus affording a more extensive and more satisfactory solution
of that tremendous Phenomenon that is furnished by the steam
of Mr Mrrcuetzt; though I am ready to admit, that in the vol-
canic actions, the production and condensation of steam, on
many occasions, has produced very powerful effects. In the
Plutonic regions, as the restraining mass was beyond all com-
parison stronger, and thicker and heavier, than in the most
violent volcanic action, it must have exerted a. power of resist-
ance greater in the same proportion ; consequently, the time of
that constraint must have been of incomparably longer dura-
tion, and the violence of the shock, when the fracture did take
place, though no less sudden, must have been vob ah
more powerful.

Thus, as Vesuvius, in: the course of the middle ages, was
once at rest during several centuries, we have reason to presume
that the Plutonic action, after being suspended for several thou-
sand years *, should ruin forward with a degree of violence pro-

portioned

* This observation. meets an objection urged against Dr Hurron by M. px
Breisiac, a gentleman. to whom I feel indebted for the handsome manner in
which he has mentioned’ the result.of my experiments, and who, on most occa-
sions, has treated. our views with peculiar fairness,. but who seems in this im-

portant

‘150 ON THE REVOLUTIONS

portioned to the time of its previous constraint, and capable of
fulfilling all the conditions of Saussurr’s debacle, or the wave of
Patias; and the existence of these tremendous events is thus
indicated @ priori by the Huttonian principles.

I shall now consider, whether such traces have not been ac-
tually left by these waves, as to place the reality of their exist-
ence beyond all doubt. We have already alluded to some of
these, and shall have occasion to mention some others ; but in
a case of this sort, no historical, nor even traditional authority
need be expected ; for though no limit could well be assigned
to the magnitude which such a wave might actually reach,
there is a decided limit to the magnitude of one that could
be recorded; since, by exterminating all witnesses, every
wave beyond a certain size would infallibly be the cause of
its own oblivion. Those of a moderate extent are most likely
to have been recorded by man, having sufficient power to pro-
duce the most awful impressions, and yet sparing a sufficient
number of witnesses to transmit the event to future genera-
tions.

In our attempts to elucidate this subject, we shall refer, in
the first place, to specimens of this tremendous phenomenon
in still lower stages of its power, since they alone have been
recorded in an authentic and intelligible form, I mean, by res
ferring to those agitations of the sea which have accompanied
most of the great Earthquakes in our own times, as we learn
from the following regular statements.

In

portant article to have altogether misapprehended the system proposed. In his
late work, (Introduction @ la Geologie, tr. Fr. p. 115.) he urges as subversive of
Dr Hurron’s views, some thermometrical observations in which the bottom of
the sea was found to be as cold as its surface. ‘To urge this as an objection,
implies that the heat employed in this system is supposed to be for ever, and
everywhere, acting upon the sand of the sea; whereas it is well known that Dr
Hurron conceived that the subterranean. heat, as well as that of the volcanoes,
was subject to short fits of activity, with ages of intermission.

OF THE EARTH'S SURFACE. 151

In the Philosophical Transactions, vol. xurx. p. 424. we
have an account of the earthquake at Cadiz, by Mr B. Bz-
wickE, merchant there, 1st November 1755, in which it is said,
* an hour after” (the first shock) “ looking out to sea, we saw a
“* wave coming, at eight miles distance, which was at least six-
“ ty feet higher than common. Every body began to tremble ;
“© the centinels left their posts, as well they did; it came
* against the west part of the town, which is very rocky ; the
* rocks abated a great deal of its force; at last it came upon
“ the walls, and beat in the breast-work, and carried pieces of
“ eight or ten tons weight, forty or fifty yards from the walls,”
&e.

We have another account of the same by Don Anvonro DE
Uttoa, Phil. Trans. vol. xurx. p. 427. who describes the wave
as having returned five times after the first*. And similar
facts are stated of other scenes of this sort. |

One circumstance in addition to those mentioned, which has
accompanied all these great events, and which seems at first
sight to contradict our explanation of them is, that in all the
agitations of the water, the first event has been a retreat of the
SCa.

Mr

* He says, “the inhabitants had scarcely begun to recover from their first
“ terror, when they saw themselves plunged into new alarms; at ten minutes
‘* past eleven, they saw, rolling towards the city, a tide of the sea, which passed
“ over the parapet of sixty feet, above the ordinary level of the water ; at thirty

minutes past eleven came a second tide, and these two were followed by four

others of the same kind, at fifty minutes past eleven ; at twelve o'clock, thirty
*‘ minutes; one o'clock, ten minutes; one o’clock, fifty minutes. The tides
“ continued, with some intervals, till the evening, but lessening. They have
“ ruined one hundred toises of the rampart, part of which, of three ee length,
“and of their whole thickness, were carried by the torrent fifty paces.” It is
remarkable, that in these six waves, the two first intervals of time are exactly of
twenty minutes each, and the three others of forty. It is sheila that they
have all resulted from one great impulse,

(34

“

152 _ ON THE REVOLUTIONS

Mr Mircuett says, Philosophical Transactions, vol. ut.
p- 566. 611. speaking of the earthquake at Lisbon in 1755,
“ the bar (at the mouth of the Tagus) was seen dry
“ from shore to shore, then suddenly the sea, like a
“ mountain, came rolling in. This phenomenon accom-
“ panied the same earthquake at the island of Madeira,
“ where we are told, that at the city of Funchal, the
“ sea, which was quite calm, was observed to retire sud-
“ denly some paces, then rising with a great swell, without the
“ least noise, and as suddenly advancing, entered the city *.”
He further states, in the same page, that “ in the northern
“ part of the island the inundation was more violent, the sea
“ yetiring there above one hundred paces at first, and sudden-
* Jy returning, overflowed the shore, forcing open doors,” &c.
Again, in page 466. he says, “ The great earthquake that de-
“ stroyed Lima and Callao in 1746, seems also to have come
“ from the sea; for several of the ports on the coast were

‘““ overwhelmed by a great wave, which did not arrive till four

“ or five minutes after the earthquake began, and which was
“ preceded by a retreat of the waters, as well as that at Lis-
“. bom.:

Looking into the original account of these calamities in Don
Antonio DE Uttoa’s Travels into South America, French
edition, vol. i. p. 467. I find that he mentions two events of
this sort, which took place at Callao; one in 1687, in which
the sea first retreated, and then returned with such force as to
overwhelm Callao and other places. And again in 1746, when,
in the course of twenty-four hours, two hundred shocks were
felt : on this occasion, the sea retiring as it had done formerly,
on similar occasions, returned furiously, and overwhelmed Cal-

lao

* Philosophical Transactions, vol. xu1x. p. 433. The retreat is Hcy pe to
have begun an hour and a half after the shock.

OF THE EARTH’S SURFACE. 153

lao so completely, that nothing remained of the whole town
but a remnant of Fort Santa Cruz. Out of twenty-three ves-
sels at anchor in the harbour, nineteen were sunk, and the four
others, one of which was a frigate, were carried to a great di-
stance on shore, and left on dry land. At Callao, out of four
thousand inhabitants, only two hundred were saved.

Mr Mrrcuerzt endeavours to account for this, by his favou-
rite doctrine of steam, according to which he conceives, that
the strata at the bottom of the sea have been raised as a roof ;
he then continues, (p. 613.) “ now while the roof is raising, the
“ waters of the ocean, over it, retreat, and flow from thence
* every way; this, however, being brought about slowly, they
“ will have time to retreat so gently, as to occason no great
“ disturbance ; but as soon ‘as some part of the roof falls in, the
“ cold water contained in its fissures mixing with the steam,
“« will immediately produce a vacuum, in the same manner as
“ the water injected into the cylinder of a steam-engine, and
“ the earth subsiding, and leaving a hollow place above, the
* waters will flow every way towards it, and cause a retreat of
*“ the sea on all the shores round about.” But the gradual
elevation of the roof, keeping tight all the while, which is here
assumed as the steam was collecting, can by no means be ad-
mitted; since, as we have shewn, a mass such as this, when
forced upwards, would have yielded suddenly.

- This phenomenon, however, along with all the rest mention-
ed, may, I conceive, be traced as consequences of the simple,
but rapid, elevation of the bottom, which we have ascribed to
the forcible introduction from below of stone in liquid fusion.

Water being almost incompressible, or elastic in an ex-
‘treme degree, it is obvious, that an elevation of that portion
‘of the fluid which lay immediately upon the part of the bot-
tom raised, would take place almost simultaneously. This
Vor. VIL U elevation

154 ON THE REVOLUTIONS

elevation would of course be the greatest in the middle, the
quantity of matter in the vertical line being the least ; but there
is no doubt that an action of the same kind, diminishing in
a high ratio, as the distance from the centre increased, would
be extended all round; the surface of the fluid being thrown
into the form of some species of conchoid, produced by the re-
volution round the vertical axis cb of the line dce, (Plate VI.
fig. 1.) the highest point of which is at c, with a contrary flex-
ure at fand h, and going off beyond these points, in such a
manner as to have the original level surface of the water dbe
for an asymptote. This conchoidal elevation, produced in the
first moment, being just equal in bulk to the quantity of water
displaced by the solid mass (a a) elevated at the bottom.

If this mass stopped suddenly, as would naturally happen,
when, in consequence of the rupture, the protruding liquid
stone has found a vent ; it is evident, that every part of the wa-
ter put in motion during the first moment, would tend, accord-
ing to the first law of motion, still to continue moying during
the next and following moments; but this tendency could not be
everywhere effectual ; because, if all the water that rose in the
first moment were to rise also in the second, a. vacuum would’
be the consequence. In the second moment, then, a struggle
must take place between the different portions of the fluid;
the middle portion, which had acquired the greatest velocity,
would continue to flow upwards, and its place not being sup-
plied from below, as, during the first moment, a suction would
be exerted downwards, upon all the surrounding fluid. The
consequence must be, that the rise which each particle would’
have performed by its separate momentum, during this seeond
moment, would be counteracted by the pressure of the atmo-
sphere, and entirely done away at a certain distance from the
centre, as at f and A, fig. 2..; beyond. that. limit the water would

sink

OF THE EARTH'S SURFACE. 155

sink below the medium level, as at k andi. An annular de-
pression would thus be produced, surrounding the central ele-
vation, vertical sections of which are exhibited by dif and
hie; that depression below the. medium level being exactly
equal in bulk to the additional elevation at the centre, occa-
sioned by the momentum, the’ vertical section of which is
fghe. The middle elevation, and the annular depression,
would continue to increase during a period, and to an
amount regulated by that class of laws, which determines
the magnitude and duration of waves, as relative to the wind
which produces them; and the water at the end of that
period would be thrown into the position denoted by the
dotted line in fig. 2., and by the single continued line in
fig. 3., indicated in both figures by the letters dk fg hie.

During a third period, the water flowing from without the
annular depression, to fill it up, a wave of depression would be
propagated outwards in all directions, and would visibly reach
to places where the elevation produced by the direct impulse
in the first moment, had not been at all perceptible, in con-
sequence of their distance from the centre. It is owing to
this cause, Iam convinced, that the catastrophes at Lisbon,
at Cadiz, at Madeira, and at Lima, in so far as the position
of the surface of the sea was concerned, were all first announ-
ced by a retreat of the sea, as shewn at m, in fig. 4.

During another successive period, the undulatory motion
continuing, the wave of elevation would advance towards the
shore at m, and being met by the retiring water, would produce
the curling form called the breaking of a wave, as shewn
at m in figure 5. At that instant the calamitous effects
described in all the great earthquakes, as resulting from the sea,
have been produced.

U2 3

156 ON THE REVOLUTIONS

I have made a few experiments lately with explosions of
some pounds of gunpowder under water, in order to try the
effect of sudden impulse. In every case, a very manifest heave
of the surface was produced at the instant of the explosion ;
and at that same instant, a very smart percussion was felt.
This was always followed in two or three seconds by a distinct
and separate agitation of the water, occasioned by the rising
of the permanently elastic gases produced in the explosion.
The form given to the wave in fig. 1. has been sketched from
the recollection of that first momentary impulse.

We have thus a theory of those waves which seem almost in-
variably to have accompanied the great earthquakes ; supposing
these to have been occasioned by submarine elevations, and to
form an intermediate step between the Volcanic eruptions, and

the truly Plutonic operations by which our continents have been.
elevated.. |

But, to return to the alpine scenes with which we set out :
If the phenomena on the banks of the lake of Geneva, to
which we have alluded, were really occasioned by a torrent of
water, its magnitude must have been such as to leave few ve-
stiges of the human race, in Europe at least, to-record the cir-
cumstance ; and we can only expect to find proofs of its reality
in geological facts. The events of Lisbon and of Callao,
though on a scale comparatively diminutive, help to lead
our imagination to the conception of this. colossal. disaster.
It may still, however, be alleged, as I have already hinted,
that it would. be impossible for:-water of any depth whatever,
or moving with any velocity, to carry blocks of'such magnitude
to such situations; and the consideration is of so great import-
ance, that TI am induced, in attempting to unite the ideas of
Saussure with those of Hutton, to retain part of the system

proposed

ON THE EARTH S SURFACE. 157

proposed by M. Wreng, in so far as to consider the granitic
blocks as having been made-to float, by means of a. mass of ice
attached to each.

‘A circumstance happened lately in this country which tends
to encourage that idea. Upon the coast of the Murray Frith,
a large block of stone, four or five feet in diameter, lying with-
in high-water mark, and well known as having served to de-
note the boundary. between two estates, was, during a stormy
night-in winter, transported to the distance of ninety yards,
and the persons upon the spot were convinced, that this mi-
gration was performed by means of a large cake-of ice, formed
round the stone, and attached to it; and that the whole had
been lifted and carried forward by the rising tide. The course
of this:stone was marked: upon the sand. below, by a deep and
broad furrow, which remained visible for a long time after-
wards, as: I have been informed by several members of this So-
ciety, who saw it after an interval of more than a year.

_ By supposing that an agent of this sort acted in concert with
our diluvian wave, the difficulty with regard. to the transpor-
tation of the granitic blocks, seems to be in-a great measure re-
moved ; and this explanation happens to be peculiarly appli-
cable to the case in point; the native place of these blocks
- being covered profusely with ice, in the state best calculated
for fulfilling the office here assgned to it. M. pe Saussure has
given the following clear account of the formation of the -Gla-
-ciers.. In any region whose temperature is-such that the heat
of summer is not sufficiently powerful to melt all the snow of
winter, the remaining snow, which, by partial thawing, and sub-
-sequent freezing, is turned into ice, must accumulate year af-
.ter year to an unbounded degree, so that the mass must be-
-come at last so lofty, as to. be unable to bear its own weight,
-and must produce a motion downwards, which will be greatly
3 assisted .

158 ON THE REVOLUTIONS

assisted by fractures, and by the sliding of the ice upon the
ground, In this manner the glaciers are produced, which con-
sist of an assemblage of great blocks of ice, each as big as a
house, which, sliding and rolling upon each other during sum-
mer, make their way from the high frozen valleys where they
were formed, through narrow glens, into the rich and warm
vales below, in which they remain a considerable time, pre-
senting a curious spectacle among the meadows and woods,
some of which they overtop. These masses, however, melt at
last, in this new situation, and leave vast assemblages_of stones,
which had been attached to them, forming a ridge called the
Marene of the Glacier.

It is obvious, then, that a wave washing over these high al-

pine valleys in summer, would float and carry off all the ice in”

the glaciers, and accumulated in the higher valleys, and, along
with the ice, all the blocks of stone imbedded in it, or attach-
ed to it in any way. The stream, with this load, would find its
way through every opening, and would in a particular manner
flow through those depressions, which at this day, as we have
said, afford a view of the snowy summit of Mont Blanc,
from certain places on the face of Jura where these blocks
abound.

_ The enormous masses already mentioned, which are found

near Geneva, and at the Coteau de Boisy, may now be ac-
’ counted for ; and the same system will apply also to the blocks
upon the Baltic, which may have been brought to their pre-
sent place, not by a permanent and steady position of the
ocean, varying by slow degrees, as has been alleged by M.
Wrentr, but by a sudden diluvian wave washing over some di-
strict, situated either at a sufficiently high level, or near enough
to the pole to be the seat of glaciers. _| Iam not at present ac-
quainted with any facts by which the native place of these

blocks

OF THE EARTH’S SURFACE. 159

blocks can be traced; but I trust we shall not long remain in
that state of uncertainty, since there are means by which that
point will be found of very easy decision, as I shall endeavour
to shew in a subsequent part of this paper, by examples in the
neighbourhood of Edinburgh.

It is well known, that granite is found native in Swe-
den; so these blocks may have been carried across the Bal-
tic, as those of Mont Blanc have crossed the valley of Geneva.
It is possible also, that they may have been transported by the
help of ice from the Alps across Germany, by the very same
torrent we have been considering, and which had left a portion
of its load behind it on Mount Jura.

This view would afford a natural account of the production
of Holland, and of a great part of that quarter of Europe,
which consists entirely of sand, and whose magnitude appears.
to me very far to surpass any deposition that could reasonably
be ascribed to the present rivers. All this sand may be con-
ceived to have been hurried along by that mighty stream, and
deposited when the torrent began to spread, and lose its force
by diffusion. It is likely, too, that an immense quantity of
this sand would be carried far into the ocean, and its deposi-
tion being there modified in various ways, by local tides and
currents, a ad assume the character of horizontal strata, so as

_ to lay the foundation for future productions of freestone or of

killas. We might thus, by the help of this diluvian agent,
complete the great circle of events, so elegantly pointed out by
Dr Horron, but which the diurnal agents seem quite insuffici-.
ent to fulfil.

As the sand was Paina upon the laud countries, the:

' blocks of granite, with their accompanying ice, from whatever

quarter they originated, would still keep floating, and thus ac-
count for a striking fact stated by M. pz Luc. He observes,
that

160 ON THE REVOLUTIONS

that the granitic blocks lying in the district between Berlin
and the Baltic Sea, occur frequently, and almost constantly, in
very numerous assemblages, upon the summits of the sandy
hills with which that country is interspersed, whilst none are
to be met with in the intervening valleys. That they also
abound on the islands of the Baltic; and these blocks shew
themselves upon, the beach only in those places where the sea
reaches the base of some of the hills on which they lie.

The present theory affords an easy solution of this fact. In
the descending stream, these hills, constituting shallow sand-
banks, would afford the first resting place for the floating
blocks of ice, which, grounding upon them, would accumulate
to very numerous assemblages, and there deposit their grani-
tic charge, while all the other similar blocks flowed onwards,
in the deep water between *.

We are thus enabled to give a tolerable account of the gra-
nite blocks; but the formation of valleys, and the excavation
of lakes, in particular of the lake of Geneva, remain to be ex-

plained.

* This aid, by which our diluvian wave is so much assisted, can be of no
‘such service to M. pe Savssure’s hypothesis, as he has originally framed it. He
conceives (art. 210, p. 141. vol. i.) that, at a period when the mountains were
covered with water, the crust was broken which defended certain caverns then
void, and the waters rushing into them with violence, left the mountains in their
present state, and, by their retreat, produced the diluvian torrent. It is plain
that such a torrent could derive no assistance from the blocks of ice. For when
this water, in its previously stagnated state, touched the solid earth, if any
blocks of ice were there, they would adhere to that solid mass, and would not be
carried off by the retiring waters; and where this water lay deep upon the solid
mass, its ice, if it had any, must have been floating at the surface, and could not
‘be attached to blocks of stone, lying of course at the bottom.

It is obvious, from the mode in which this topic is introduced by M. pe Saus-
surE, (which he does, as he expressly says, to meet the impatience of his reader,)
that he is not satisfied with it himself, nor can it bear the slightest examina-

tion.

OF THE EARTH'S SURFACE. 161

plained. I trust, however, that the same principles will extri-
eate us from this difficulty also.

If my view is correct, as to the violent manner in which our
continents have risen from the bottom of the sea, to their ut-
most elevation in the atmosphere, it is quite obvious, that the
cold and hard external crust, while it communicated such
shocks to the ocean, must itself have undergone the greatest
agitation, and must have been rent and broken in every con-
ceivable mode. The stone, in liquid fusion, introduced into
the rents, would assist the elevation, in so far as it tended to
facilitate the shifts, by enabling one mass to slide on the other ;.
but forcing its way upwards, this liquid would at last reach a
temperature, in which, as we have said, it would congeal ; its
further progress in that direction, with respect to the neigh-
bouring substance, being thus effectually stopt, and the propel-.
ling force from below. continuing to act, the local elevation would
be converted into a more general one, either where the strata
were in a flexible state, by means of an horizontal thrust, pro--
ducing an elevation along with the convolution of the strata,
(in a manner lately pointed out in this Society), or, where the
neighbouring substances were inflexible, by a penetration of
the liquid through the mass, giving rise also to a vertical heave
of the whole. Ia either case, a number of rents would be
formed, in the hard outer crust, which would widen upwards
as the heave advanced *, thus forming the rudiments of valleys

Vor. VIL. | x: of

_* This elevation may be illustrated, by the familiar example of what happens-
in the act of digging a piece of firm soil. The gardener first thrusts his spade into
the unbroken ground, then leaning on the handle, gradually forces the flat iron up-.
wards; by this means, a heave of the soil takes place; the middle part being
raised, while the sides remain more or less attached to the firm soil. A separa-
tion between the two is the consequence ; and a formation of rents open upwards..
which gradually become wider and wider as the spade rises.

162 ON THE REVOLUTIONS

of every degree of wideness, from the narrowest ravine to the
most open vale.

All this progress, or at least great part of it, being perform-
ed by successive starts, each of which, while under water, pro-
ducing a tremendous wave; the mass, in rising, would be re-
peatedly exposed to these diluvian torrents, some formed by
itself, and some by neighbouring elevations, so as at last, after
long exposure to agents, fairey diluvian and partly diurnal, ‘it
would arrive at its present situation and condition.

In consequence of the diversity of these elevations in place
and in magnitude, acting upon substances of every sort, an
endless diversity of effect would be the result. In some cases
a rent, in consequence of the locality of the heave, would be
rendered both large and deep in the middle, while it remained
nearly closed at both ends. Water, therefore, could not flow
through it without stagnating by the way, and thus a lake
would be formed, the depth of which might be very great in
the middle, though its extremities were shallow. This applies
to the formation of the lake of Geneva, either before or since
the passage of the granitic blocks. It is applicable also to
all lakes which occur in alpine or rocky districts. It will ap-
pear in what follows, that an account no less satisfactory may
be given on other principles of those which belong to alluvial
countries.

_ An example of the relative changes among rocks, produced
by motions of this sort, occurs in the mass on the coast of Ber-
wickshire, with which we have been so much occupied in a for-
mer meeting, as affording a display of the convolutions of the
strata. Upon this coast, the killas and sandstone meet on the
East near Eyemouth, and on the West in the parish of Cock-
burnspath, at the Siccar Point, where the junction is beautiful-

ly

OF THE EARTH’S SURFACE. 163

ly displayed. In the neighbourhood of both junctions, the sand-
stone strata, laid open by the shore, present to view a striking
picture of former revolutions, as | have endeavoured to repre-
sent by two sketches taken upon the spot. One is at the Hal-
lahole near the Press, between Berwick and Eyemouth (Plate
VIL.) on the east ; and the other at the Coveshore (Plate VILL)
in the parish of Cockburnspath on the west.

In both, the sandstone, remote from the junction, is seen in
an horizontal position, which seems to be its general character,
and which upon the West it maintains to a great extent ; but in
the neighbourhood of the junction, the beds become absolute-
ly perpendicular, in a rock which, in both cases, rises to the
height of thirty or forty feet. This change of position takes
place differently in the two cases. ‘That upon the East is sud-
den and immediate, the whole change being performed in a
single cliff, at the bottom of which the beds are horizontal, and
at its summit vertical, nay, leaning over upon themselves ; on
the other it is gradual, the strata being seen in succession to
pass through every intermediate declivity, the change occupy-
ing more than a mile of coast.

This local elevation seems unequivocally to denote a great
perpendicular shift. kither the sandstone mass has sunk and
left the killas behind it, or the killas has risen from below,
leaving the sandstone, and dragging its contiguous beds partly
up along with it. As we know that the whole once lay deep
below the sea, and that it is now raised, it seems more simple
to ascribe these changes.to one action, and. to believe that the
last supposition is the true one. ,

_A fact which I witnessed in Calabria, not long after it occur-
red, belongs to the same class, and may bear a similar inter-
pretation. What is called the Plain of Calabria is an alluvial

MOQv aoi district,

164 ON THE REVOLUTIONS

sdistrict, situated along the western coast, behind which there
rises a ridge of primitive mountains. When the terrible earth-
quake of 1783 took place, a very extraordinary circumstance
happened, the remains of which I went to see in 1785, and
found it corresponding to DoLomizv’s description. A naked
scar of red earth, facing the plain, made its appearance upon
the primitive mass, all along the line of junction between the
two; this scar being ten or fifteen feet high, and appearing al-
most universally in a tract of many miles. Dotomrev has gi-
ven an ingenious theory of this phenomenon, which appeared
to me satisfactory at the time. He supposes, that in conse-
quence of the agitation of the alluvial mass by the earthquake,
it had undergone a subsidence, or tassement (as it is expressed
in French), similar to what happens when a bushel of wheat is
struck by the hand ; and that in consequence of the subsidence
of the loose country, the firm country had been left behind. I
am now, however, inclined to suggest a different explanation
of the same fact, and to connect it, by analogy, with some of
those lately mentioned, by conceiving that the middle, or rocky
mass, may have been raised, leaving the alluvial mass behind
it, and that its motion has been the proximate cause of the
earthquake. It may further be observed, in favour of this
view, that if the alluvial mass did subside in the manner point-
ed out by Dotomtsu, the districts in the neighbourhood of the
sea must have been submerged. It would have been easy, if
such a conjecture had occurred on the spot, to bring it to the
test of observation; for the opposite side of the coast of the
peninsula must have furnished some facts either in confirma-
tion or refutation of the idea. I mention it here, as a hint to

future travellers, in tracing the result of earthquakes.
I cannot too strongly recommend to geological travellers, the
examination of those scenes where earthquakes, and their at-
tendant

OF THE EARTH'S SURFACE. — 165
tendant waves, have exerted their influence, and which have
probably left behind them very striking monuments of their
power. I conceive that in this way, the doctrines already ad-
vanced in this paper, and which I am now about more fully
to illustrate, will be submitted to the test of direct cbserva-
tion.

‘The fact which I have met with most strictly in point, oc-
curs in Humsoxtpt’s Account of Mexico, Eng. Trans. London,
1811, vol. ii. p. 212. At San Pedro de Jerullo, “in the month
“ of June 1759, a subterraneous noise was heard. Hollow
* noises of a most alarming nature (bramidos) were accompa-
* nied by frequent earthquakes, which succeeded one another
“ from fifty to sixty days, to the great consternation of the in-
“ habitants of the Hacienda. From the beginning of Septem-
“ ber, every thing seemed to announce the complete re-esta-
“ blishment of tranquillity, when, in the night between the
“ 28th and 29th, the horrible subterraneous noise recommen-
“ ced. The affrighted inhabitants fled to the mountains of
* Aguasarco. <A tract of ground, from three to four square
“« miles in extent, which goes by the name of the Malpays,
** rose up in the shape of a bladder. The bounds of this con-
+ yulsion are still distinguishable in the fractured strata. The
“ Malpays near its edges is only twelve metres (thirty-nine
* feet) above the old level of the plain, called Playas de Jo-
“ rullo; but the convexity of the ground thus thrown up, in-
“ creases progressively towards the centre, to an elevation of
“ one hundred and sixty metres (five hundred and twenty-four
“+ feet).””

a

Lal

Lad

oO

In this most striking and interesting scene, we have an ac-
tual specimen of those violent and sudden operations by which
our continents have been raised to their present position, ac-

cording

166 ON THE REVOLUTIONS

cording to my view of Dr Hurron’s Theory; and had, this
event come to his. knowledge, which happened im his day, it
might have induced him to admit the probability of those sud-
den elevations, indicated by so many facts.

The process of elevation, whether performed gently or
rapidly, is free from a difficulty to which the systems of
beth Saussure and Werner are exposed: both of these geo-
logists conceive that our continents and rocky districts were
ence covered with water, which has since flowed away,
these rocks maintaining their original position; now, to
lay a rock bare in this manner, we must dispose not only of
the water which covered the immediate mass of rock, but also
of that body of the same fluid which occupied an equal level
all over the globe. This difficulty was strongly felt by Professor
Pauxas, who says, (Observations sur la Formation des Montagnes,
p. 79.), that were the summits of the mountains supposed to
have been covered, the mass of water required to equal and
surmount them round all the globe could not be disposed
of within the earth, even were its inside made up of ca-
verns: On that account, he denies that the summit of the
hills has been covered. He burdens himself, however, with a
very considerable share of the same difficulty, by supposing
that the sea had stood at such a level as to submerge hills of
100 fathoms high.

According to our theory, there is no such embarrassment.
We suppose these low hills, as well as the high ones, to have
been raised from the bottom of the sea, which need not be
considered as ever having stood above its present level. And
I think myself authorised by the facts stated in the course
of this paper, in deviating so far from the Huttonian hypo-
thesis, as to believe that the elevation of the land was per-

| formed.

OF THE EARTH'S SURFACE. 167

formed by successive starts, similar to volcanic eruptions,
though far more rare and more powerful; and that the per-
cussions impressed by these starts upon the waters of the
ocean, were such as to form waves, sometimes of a moderate
force, as those at Lisbon or Callao; sometimes of overwhelm-
ing magnitude, and capable of producing the effects described
in the Alps, in Germany, and in Russia. }

As the inferences derived from these distant facts are called
in question by some gentlemen of the highest authority in this
Society, I am happy to have it in my power to produce a set
of observations made in this immediate neighbourhood, which
seem in a manner no less satisfactory, to lead to similar con-
clusions. These are the subject of the second part of this com-
munication.

PART II.

“noo Velie OB 84
inde afte ye Sify Vote
se ne, rex rnpeeton A 0) AD Heong iB
nA ¥ eee Psy het shady say ay
i cenctltenin | Mite ition it aati
1 Nha aire. Ae, Oren otras igre
versed Qa, sa? estat 5 Oy SRS OR mA nga gh
ADTS NT, 00 Na ted ote debe: aoe aoe
; oes heise’ oy toy ae faa elie! Meee eran), ccaoudies pt
“it Mies ee. en aan: «hel clement t Roend cadner~ebipaaanes:e
measait ines aah Lor oe teens tu ones Yt ye aE
o eaeeamcagilie Ce a ee
4 dynes shee wleowagm ho} liptowes x9 vor ua jamergie =
Ota, Yaar bene st, asa age Soy vie 0 teh, eda
sur wie Ms Cage, eo) thn endian a rwas: | ‘ t
aga ose: ata papi 0cSea age ha nae ose
St vvetlAl vll 2c aga 9 tie: “nn
CAM WA Lene hom Geren eine
Aho teenies ton ates previ ta 1 itt + diipea eval iteyn

a

Liat pp imae, teks <a aly Cabs aidenondiias Ce
vt ¢ wine

~~ =

V. On the Revolutions of the Earth’s Surface. By Sir James
Haut, Bart. Pr. R. S. En. & F.R.S. Lown.

PART II.

BEING AN ACCOUNT OF THE DILUVIAN FACTS IN THE NEIGHBOUR-
HOOD OF EDINBURGH.

[Read June 8. 1812.]

F such tremendous agents did in reality exert their influence
in the Alps, it is not conceivable that other countries, si-
tuated lower, and composed of materials much more frail,
could have been spared. We hear in fact of similar traces,
more or less distinct, in all quarters of the globe. From the
bones of animals, natives of the hottest climates, which are
found over a frozen region of vast extent in the Russian em-
pire, Patias* concludes, that an enormous torrent had trans-
ported their carcases across the ridge of Tartary.
Vou. VIL Y | On

* Observations. sur la Formation des Montagnes, p. 71. Nov. Com. Petr.
tom. xvir. p. 576.

170 ON THE REVOLUTIONS

On my return from the Alps, looking for traces of the same-
agents in this country, I found them in abundance, particu-
larly in the neighbourhood of Edinburgh ; and the circumstan- —
ces of this sort which I have met with, both on a large scale.
and in detail, seem to afford more precise information as to
these events than has hitherto been furnished by the alpine
phenomena.

In order to acquire principles upon which these ‘observations
may be made to advantage, and by which the truth or false-
hood of the systems to which they lead may be brought. to a.
certain test, it is of importance to examine the results of simi-
lar actions, in such analogous cases as lie in all respects within.
reach of observation. Ifa torrent, like that which is supposed
to have inundated the Alps, had flowed over this country, it
must have left behind it traces of various sorts, resembling in
some degree those that occur in the course of any common
river which has recently overflowed its banks. Thus in both
cases, sand and mud, and loose stones, must have been transport-
ed and deposited ; and fixed objects must have been overwhelm-
ed and. abraded, by the action of the water and of these mo-
ving bodies: The relation. of the stream to these objects, either
met. or transported, is very different, it is true, in the two
cases ; but a sufficient agreement exists between them to an
us on the present occasion.

It is an undoubted truth, that where an obstacle occurs in
the course of a fluid, which is in the act of transporting and
depositing heavy substances, the deposition in the neighbour-
hood of that obstacle undergoes considerable modification.
The theory of these modifications would be difficult to deter-
mine ; but their effects may easily be traced, by observation in
the bed of any stream after a flood, or in the drifting of snow,
fallen during a high wind, or which is in the act of falling.

Where

OF THE EARTH'S SURFACE. 171i

Where the obstacle is high and narrow ; where its height, for
instance, is at least equal to its breadth, we perceive that a
stagnation of the fluid takes place on the side towards which
the stream is flowing, and a deposition is formed of the trans-
ported substances, constituting’a tail or prolongation, which ex-
tends in the direction of the stream, by a gradual descent to
the distance frequently of eight or ten times the height of the
obstacle. At the same time, an acceleration is occasioned at
certain places in the neighbourhood, by which the general de-
position, which was going on at the time, and which would
have been universal had no interruption occurred, is there
prevented. This acceleration takes place along that face of
the obstacle which fronts the stream, along both its sides, and
along those of the tail, forming by the stagnation just men-
tioned: the consequence is the production of a hollow or de-
pression in all those places, below the level of the general de-
position in the neighbourhood. The case is different where
the obstacle is of great breadth compared with its height.
When its breadth, for example, is five or six times greater than
its height, the effect is often reversed, and an excavation is
occasioned on the side towards which the stream is flowing.

The action of a current of water upon sand, or of wind upon
snow, previously deposited, produces effects similar to those
just pointed out. Thus, a firm body, occurring in the midst
of such an assemblage, mitigates or prevents the action be-
hind the obstacle, that is, on the side’ towards which the cur-
rent is flowing, and, at the same time, augments the corrosive
energy in front of it, and along the two sides. Effects are
thus produced similar to those in the case last mentioned ; and
it may be difficult in many cases to determine whether a par-
ticular assemblage has been produced, by a modification of the
first deposition, or by 3 second action upon an assemblage pre-

| Y2 viously

niZ ON THE REVOLUTIONS:

viously formed. The action of a current, with the assistance-
of the solid masses of every size transported by it, upon the
substance of any solid rock opposed to it, is subject to certain
laws, the principles of which must, in many respects, be com-
mon to it in the two cases just mentioned, as we shall have oc-
casion to point out more fully in the course of this paper.

In attempting to apply these principles to the great scale of
geology, and to vindicate my opinions on this curious sub-
ject, I shall appeal to a series of facts which are very accessible
to this assembly, the greatest part of them lying within two or
three miles of this city. In that view, I have given, along with
this paper, a plan, on actual survey, taken on this account, of
a small district in the neighbourhood of Edinburgh, compre-
hending the Corstorphine Hill and its. immediate neighbour-

hood. I thus hope to indicate the place:of each specimen al-

_luded to, in such a manner, that, provided the rock remains in.
existence, it may be in the power of an observer to discover it
at any future period, however much. it may have been con-
cealed by the accidents to which such specimens: are perpe-
tually exposed..

The country in the: neighbourhood of Edinburgh is what all
are agreed to call Secondary, consisting of beds of sandstone,
and. occasionally of limestone and coal, interstratified with
thick assemblages, ef shale, in loose and frail strata. This mass

_is traversed with the utmost irregularity, by dikes or veins of
_whinstone, which occur also in vast interjected masses, some-
times lying in great amorphous blocks, and sometimes in thick
_beds, parallel to the strata. The strata, themselves, as might
be expected, are thrown, by means of its intrusion, into much
irregularity, and though nearly parallel to each other in any
particular spot, exhibit the utmost variety, when different places
_are compared together, as to their dip and direction. This

contrast

OF THE EARTH'S SURFACE. 173

contrast is conspicuous in Salisbury Craig on the east, and in
Corstorphine Hill on the west of Edinburgh. Each consists:
of a thick mass of whinstone, parallel to the strata beneath it,
which, in the first mentioned hill, dip rapidly to the east, and
in the second to the west.

The surface of this district, together with the alluvial part
ofi ts mass, bears every mark of the effects which a wave of
sufficient magnitude to overwhelm it, might be expected to
occasion upon so multifarious an assemblage. .

Raised from below by the violent and abrupt means already
alluded: to, in my-last communication to the Society, this dis-
trict would present to a stream overwhelming it at any subse-
quent period, numberless points of attack. Many of the
rocks being rent in various ways, the hardest parts being in a
shivered, state, would easily be carried forward. The soft
beds of shale or slate-clay being laid open to the attacks
of the- current, would: be. deeply abraded» by its. action,
and thus masses, both. stratified and unstratified, that were
originally unbroken, would be undermined, and, yielding to
‘ their own weight, would add to the quantity of moving
matter, and extend the field of attack upon the weaker
parts. The water would thus be loaded with a multitude of
blocks of every size, shape, and quality, and with a quantity of
clay, which being soon reduced to mud, through which these
stones were irregularly and confusedly scattered, would flow at
the bottom of the water, and along with it, and would be de-
posited, according to the laws already pointed out, when the
stream approached to a state of rest. Such seems to have been
the origin of that body. of compact blue clay which forms a
material part of our low districts, bearing every indication of
having flowed as a mass into its present situation ; for it is to-
tally devoid of stratification, though frequently bf great thick-

ness.

174 ON THE -REVOLUTIONS

ness. ‘This mass shews itself in several places, in the bed of
the water of Leith, where the banks have been laid open by
natural or artificial means. It was well displayed formerly,
and may still be seen above the Bells’ Mills Quarry, and is
now exposed to view upon the right hand, after crossing the
Dean Bridge, on the old road to Queensferry. It here pre-
sents to view a face of about twenty or thirty feet deep, though
it often extends to forty or fifty feet. We find it also upon the
shore to the west of Leith, as laid open by the sea; and I am
informed by the person who conducted the work, that at the
Fort in that neighbourhood, in a search for water, it has been
penetrated to the depth of eighty feet from the surface, being
fifty below high-water mark. It is obvious, that the power of
such mud, when flowing as a stream, in transporting heavy
bodies, and in abrading ‘assemblages previously formed, must
bear some relation to the resistance which it would oppose to
any object forced through it, and of course, that its power in
these respects must have been much superior to that of pure
water. I conceive also, that a deep stream must exert a great-
er power of transportation and corrosion than one which is
shallow, flowing with the same ‘velocity.

The existence of assemblages of this sort, affords, by its
simple testimony, a powerful argument in favour of a stream
having overflowed this country, superior in magnitude to any
‘known river; and the facts seem to meet the challenge held
out by Mr Puayrair in the following passage, J//ustrations,
art. 366. “ Lastly,” he says, “ if there were anywhere a hill,
‘“* or any large mass composed of broken and shapeless stones,
“ thrown together like rubbish, and neither worked into gra-
“ vel, nor disposed with any regularity, we must ascribe it to
“ some other cause than the ordinary detritus and wasting of
‘the land. This, however, has never yet occurred, and it

** seems

a

—

OF THE EARTH'S SURFACE. 175

*“ seems best to wait till the phenomenon is observed before
* we seek for the explanation of it.”

Now it appears to me, that these vast assemblages, in which
blocks of every size, and shape, and quality, some sharp, some
round, are confusedly scattered through clay, are inexplicable
by any diurnal cause, and do call for some particular solu-
tion. ;

Such parts of the torrent as.encountered less of the strata of -
shale and clay, would hurry along with them the comminuted.
sandstoné, and deposite it in the form of sand:and of gravel.
Vast accumulations have thus-been formed in all our lower di-
stricts, the external figure of which, and of the clay, has acqui-
red, as we shall soon have occasion to point out, a character pe-
culiar to itself, and having externally a smoothness and regu-
larity, which forms a striking contrast with the abrupt and
most irregular dislocation which very commonly occurs in the
solid mass within...

In the midst of this general wreck of all the frail parts, the
strongest masses,. principally those which, like Arthur’s Seat,
have been powerfully. pervaded with whinstone, would resist
and defy all the impetuosity of the stream. The principles
which we have endeavoured to lay down, as to the influence of
firm obstacles on depositions and abrasions, would thus be
brought into action.

The rock upon which the Castle of Edinburgh stands, toge-
ther with the site of the Old Town, exhibit the most perfect
example that could be conceived of the application of these
principles. The rock itself, about two hundred feet in height,
above its base, and bare on three-fourths of its circumference,
consists of one of the most complete and uniform masses of
whinstone that is known in this country. Its form is rudely
cylindrical, and from it the ridge upon which the Old Town

stands,

L76 ON THE REVOLUTIONS

stands, composed partly of deposites, and partly of protected
strata, extends, gently sloping, for about a mile to the east-
ward, from the Castle to the Abbey of Holyroodhouse, where
the tail terminates. Round the western, southern, and north-
ern sides, a hollow valley occurs, which, towards the north, is

still a marsh, and was once a lake, being known by the name .

of the North Loch. |

Corstorphine Hill, which, as seen from Edinburgh, occupies
the horizon to the north-west, affords, in one respect, an ex-
ample of the other case just mentioned. — It consists of a ridge
* of about a mile and a half in extent, rising in the middle, de-
clining gently at both ends, and pointing from north to south,
with a declination of about 20° to the east. It presents a
smooth face of whinstone to the west, towards which the mass
dips in parallelism with the strata beneath it. Upon its eastern
side a hollow valley occurs, in which the old castle of Craig-
crook stands, and from its southern extremity a tail extends to
the eastward, lying between Ravelstone and Murrayfield, upon
the southern face of which Murrayfield stands.

Thus, the Castle of Edinburgh, gives an example of the ef-
fect of a-narrow obstacle; and this hill, of a broad one, in so
‘far as it has a valley on the side towards which the stream was
flowing.

We have endeavoured, in the last communication to this So-
ciety, to account for the formation of such lakes as occur in
alpine and rocky districts. The circumstances just pointed
out, explain the formation of those which belong to districts
formed of frail and moveable substances. At Lochend a stri-
king example cccurs, of a lake produced upon the upper side
of an obstacle, in consequence of local acceleration.

Immediately on the east of Corstorphine Hill, a set of firm
zocks, or little hills of sandstone occur, rising up fou this hol-

low,

OF THE EARTH'S SURFACE. a77

low, or standing upon its eastern side. Of these, Ravelstone,
Craigleith, and Blackcraig, are the principal, well known as ex-
cellent quarries. From each of them a tail or prolongation
extends to the eastward, formed chiefly of the blue clay alrea-
dy mentioned, together with beds of sand and gravel. These
decline very gently, and maintain, to a considerable distance,
the individual character given to each by the firm mass produ-
cing it. These ridges, however, are occasionally interrupted
by the interference of the same principles ; as we see well illu-
strated near the rock of Craigleith Quarry, by which the tail
extending from the Maiden Craig, (another sandstone mass to
the westward of it,) is abruptly cut off.

_ From Corstorphine Hill to the eastward, the country em-
bracing all the space between Edinburgh and the sea presents
one continued series of ridges, upon one of which the New
Town of Edinburgh stands. It is an important circumstance,
that these ridges maintain a very correct parallelism with each
other, with the tail of the Castle rock, and of the Calton Hill,
and with the alluvial prolongations that extend to the eastward
from all the eminences of this neighbourhood. And a series
of parallel ridges occur also on the south side of Edinburgh,
extending from all the rocky eminences, as may be well seen
on the read leading to Dalkeith, which passes over several of
these; one of the most remarkable of which is, that on which
the village of Libberton stands.

Such an arrangement cannot have been the work of the
diurnal waters produced by our common rains; for the
course of such waters, flowing by the action of gravity,
and guided by the general slope of the country, which de-
clines towards the Frith of Forth, ought to have produced
depositions nearly at right angles to those under considera-
tion. It is in vain that a vast duration is ascribed to the influ-

Vou. VII. Zz ence

178 ON THE REVOLUTIONS

ence of an agent, unless it can be shewn, that its action has a
tendency to produce the alleged result. If it has a tendency to
produce a different result, that difference would be augmented
in proportion to the duration of the action. Now, the diurnal
operations are everywhere found in the act of corroding and
altering the forms here alluded to * ; but they are nowhere seen
to produce them. This class of facts, on the other hand, all

conspire in giving probability to the hypothesis of a diluvian -

wave, which affords an easy explanation of all the large features
of this country.

An important principle of the theory of running streams
must here also be considered, namely, that the shape assumed

by such a stream flowing through sand or other loose matter,

bears a distinct relation to the magnitude of the stream; the
radius of curvature of its bendings being in proportion to that
magnitude. Thus, all the water collected from this neighbour-
hood, is capable of producing no more than a paltry brook,
as appears from the Water of Leith, which we see meander-
ing between two of the ridges just mentioned. This meander-.
ing course, suits the diminutive size of the brook; whereas
these ridges being straight, or, mathematically speaking, having
a curvature whose radius is of infinite length, we are led, by a
very obvious analogy, and in concurrence with what has been
observsd in other parts of the globe, to believe that a cause
very different from any now in activity, and far more power-
ful, has exerted its influence upon this spot; that a stream

has

* As is very apparent upon some of the ridges last mentioned, as we see on

the road to Dalkeith, just as we leave Edinburgh. Some ravines there present.
themselves in front, and on the right hand, descending the northern side of the
ridge, and denoting a genuine diurnal action, in obedience to the mere action of
gravity.

. Se ee.

a ie ooo)

OF THE EARTH S SURFACE. 179

has flowed over it, capable of: overwhelming and disregarding
objects by which the Nile or the Ganges would have been
turned out of their course.

But the testimonies in favour of this hypothesis are not de-
rived from these large features alone; and it is not concei-
vable, that such agents could have been at work, without leay-
ing behind them indications of their influence still more un-
equivocal. These occur in the very places indicated by the
theory, and exhibit remarkable instances of abrasion. In
order to investigate them with success, we must have recourse
once more to the effects produced by one of our common
streams. .

Where a firm rock of any kind has been exposed to the action
of a rapid river, its surface acquires in consequence of that abra-
sion a peculiar character, which every one recognizes at a
glance, but which it is difficult to describe in words. The
most obvious and universal effect of such an_action, is the
rounding of all the original angles of the rock ; not only the pro-
minent, but also the entering angles. For where an original
hollow has occurred, coinciding at all with the course of the
stream, the water has undergone an acceleration along that
hollow, and has excavated for itself a waving groove more or
less longitudinal. The whole has thus acquired a pecu-
liar character, by an assemblage of flowing lines, which re-
calls the water-worn state of the rock. Another set of
forms also present themselves in all such cases, which could
not easily have been foreseen, and whose existence we
learn only from observation of the fact: we observe, that
the surface is in many parts excavated by shallow depres-
sions of various sizes, which I shall distinguish by the name of
scoopings, as resembling the effect which would be produced
upon a soft body by the oblique blow of a spoon or scoop. I

Z 2 conceive

180 ON THE REVOLUTIONS

conceive that they have in fact been produced by the action of
eddies of inferior force to the main stream, but acting in com+
pany with it in different, and sometimes opposite directions.
These various corrosions going on together, have each produced
its peculiar effect; and most of them being concave, their
meeting has given rise to the set of waving angular ridges
which constitute the most unequivocal feature of a water-worn
rock. These angular forms differ completely from those which
occur in the broken surface of a rock. These last are acute,
rectilinear and abrupt; while those others are continuous,
flowing, and having their angles very obtuse ; so obtuse in
some cases, as not to be visible, unless the light strikes upon
the rock in a peculiar direction *.

In a small but rapid brook near my house in the country,
these forms occur on the surface of a smooth bed of sandstone
over which it flows. I observed lately, when the brook was
low and clear, that, to a certain distance below each of these
obtuse-angled ridges, the rock was covered with green moss,
while above the angle it was bare. The mode in which these
forms are produced and maintained, seems thus to be pointed
out: the main stream being possessed: of just. power enough
to keep the rock clear of moss, and the eddy being too weak
for this purpose. In a flood, L presume that the eddy acquires
such power, that the whole rock is cleared.

In

* T have endeavoured, as yet without success, to make or procure an adequate
representation of these forms; but I do not despair of overcoming this difficulty,
and of being able, on some future occasion, to lay something of the kind before
this Society that may not be unworthy of their notice. In this undertaking, I
hope for the assistance of a very masterly artist, who is interested in the investi-
gation, and who has already rendered me great services in this and other pup-

suits.

OF THE EARTH’S SURFACE. 181

In whatever manner we account for the production of these
forms, it is certain, that they present themselves on the sur-
face of water-worn rocks. I have also observed them upon
the surface of a mass of snow which had been acted upon, and
partly removed by a strong wind. As the abrasion occasioned
by a fluid in motion seems alone to possess that power, we
-may reasonably conclude, then, that a fluid has acted where
such forms occur.

Now, it is a fact of which I shall presently lay various ex-
amples before this assembly, that the very rocks over which,
according to the theory advanced in this paper, torrents of wa-
ter have flowed, loaded with sand, and gravel, and large stones,
and accompanied with streams of mud, are found to exhibit at
their surface all the characters of abrasion lately mentioned ;
—the rotundity and flowing: character ;—the excavation of hol-
lows into the form of waving grooves ;—the concave scoopings,
and the obtuse-angled, and waving ridges. Circumstances,
then, seem to justify the conclusion, that, in fact, mighty tor-
rents have traversed these-districts. - .

In addition to the facts mentioned, and in company with
them, another set also occur in these scenes, which powerfully
corroborate the same conclusion. As stones of considerable
bulk are often carried down by torrents, it is reasonable to ex-
pect, that upon rocks along which they have been hurried,
and on which they could not fail to act as grinders, traces
should shew themselves of that passage by scratches and
abrasions of various sorts; and I have little doubt, that such
will be found, when the effects of great floods in rapid rivers
are properly examined ; especially where a stream of mud has
accompanied the torrent. Not having had occasion, however,
to visit any scene of this sort, since the importance of the ob-
servation occurred. to me, I have as yet, only met in rivers

with

182 ON THE REVOLUTIONS

with cases in which the surface of the rock has been dressed to
smoothness, and in which the abrasion shews itself in the ge-
neral rotundity of the grooves and scoopings, and in the obtuse
angled and waving ridges just described *.

But what I have hitherto looked for in vain in common ri-
vers, occurs universally in the diluvian scenes, where there is
reason, from other circumstances,to believe, that a powerful abra-
sion has taken place, and where the surface has been protected
from the injuries of the weather. Where it has been exposed
to that injury, we generally find, that the large features of
dressing, the grooves and scoopings, and obtuse-angled ridges,
only remain. But where a mass of this kind, either by acci-
dent or design, has been followed under ground to where its
surface has been protected by a covering of clay, an interest-
ing and striking scene presents itself; the surface is found to
resemble that of a wet road, along which a number of heavy
and irregular bodies have been recently dragged; indicating
that every block that passed, and every one of its corners, had
left its trace behind it; and these are rendered very distinctly
visible, when the surface is drenched with water.

In many cases these furrows or scratches have been so deep
as to resist all the effects of the weather, and shew them-
selves in rocks that have been always exposed, sometimes

many

* The only case which has as yet occurred to me, bearing any relation to the
action here alluded to, arose from a cause seemingly quite insignificant. Ina
neighbouring county, a country house, situated upon the slope of a hill, was as-
sailed by a sudden torrent of water, produced by the bursting of a thunder-storm
on the hill above. The impetuosity of the stream was such, that it forced its
way through the under storey of the house, carrying along with it quantities of
sand and gravel, and stones of considerable bulk. Happening to be upon the
spot a few weeks after the accident took place, I observed, that every stone, as
it passed through the house, had left a rut or scratch behind it, upon the flags
ever which it passed.

QQ’ Sees oe a ee

OF THE EARTH'S SURFACE. 183

many yards in length. Occasionally, single scratches, and pa-
rallel sets of them, deviate by five or six degrees from the ge-
neral direction ; but the important circumstance is, that such
deviation is rare, the very great majority of both sets agreeing
in parallelism with each other, and with the general direction,
not only of the scoops and grooves of the rock upon which
they occur, but also of the ridges and large features of the di-
strict. A rock covered with these furrows, has externally an
appearance greatly resembling what is called Slickenside, with
this difference, that in the slickenside, we can always discover
some proof that one portion of the main rock has performed a
small slide upon the other ; whereas, in this case, every thing
shews, that the rock ae consideration has stood firm, and
has been abraded by a number of bodies in motion. The cir-
cumstance just mentioned, of occasional deviations from paral-
lelism, seems also to distinguish this form from the slicken-
side ; in which last, I believe, the lines are invariably paral-
lel *.

The direction of the ‘stream in the neighbourhood of Edin-
burgh, as indicated by the medium result of a number of ob-
servations, appears to have been from 10° S. of W. to 10° N..
of E., by true bearings taken with a needle, and allowing
271 degrees west of north as the variation; and I have met

with

* They are also distinguished by this, that in the case of Slickenside, the rock
has always upon it a crust of calcareous spar or zeolite, which seems to have oc-
cupied a vein. Both sets seem to have been the result of mechanical action. The
slickenside has been produced, I conceive, in the Plutonic regions, at a time when
the mass in general has been:so far cooled, as to be solid, though sufficient heat
has remained to keep the fusible matter, as carbonate of lime or zeolite, which
filled the vein, in a.state at least of semifusion ; so that in the sliding of one mass
on the other, it has acted like grease in the wheel of a carriage: this pane ace.
aes for the parallelism of the lines of slickenside.

184 -ON THE REVOLUTIONS

with no case deviating more than 10° or 12° from that average
on either side *.

Specimens.

_ [shall now describe the situation of fifteen specimens around
Corstorphine Hill, denoted in Plate [X. by the number of
each inclosed in a little circle.

No 1. The first is upon the rock at Craigleith, part of which
is now worked as a quarry. It is a very complete and firm
sandstone, and, as I have already mentioned, stands up, in the
course of our supposed stream, to the height of forty or fifty
feet, having a long projecting tail to the eastward, similar, on
a small scale, to that of Edinburgh. It has likewise, on its
western side, an excavation similar to that which forms the

North Loch, but on a proportionally small scale.

_ This rock had lain bare, and open to the day on its wester-
ly front, and it everywhere presents to view, where not con-
cealed by the rubbish of the quarry, that rotundity of form
which might be expected in such a situation, though, by its ex-

, posure

* I am aware, that the usual mode is to describe the direction of a current at
sea, by stating the point towards which it flows. But my object, on this occa-
sion, being to trace the origin of these currents, I have been induced to follow an
opposite mode, and in general to denote the course by the point from whence
the stream has been supposed to flow. In the following descriptions, the prin-
cipal object of which is to mark the place of each specimen, I have frequently

omitted the direction, in order to avoid interruption. But these directions have
been carefully observed, and may be seen by turning to the page at the end of |

this paper, where they are all placed in one column, each opposite to the name
of the spot, and to its number.

s
:

OF THE EARTH'S SURFACE. 185

posure to the air, it has here lost every other symptom of dilu-
vian action. Another face of the same rock, sloping to the
south, which occupies the left hand mass of rock on the entry
to the quarry from the south, which has lately been freed of its
alluvial covering, exhibits the same rotundity of form, with the
addition of the more minute circumstances of dressing, in high
perfection. The space here laid bare is about ten paces by
three. The upper portion is nearly flat; a great part of the
surface inclines rapidly to the south; indeed, in some places,
it is almost perpendicular. ‘The perpendicular face, as well as
the rest, is covered with furrows and dressings, indicating that
the grinders had been pressed against the rock by the impetu-
osity of the stream, independently of their gravity ; for almost
the whole of these dressings are horizontal, or nearly so.
There are some, however, which cut the rest at an angle of five
or six degrees, or even ten degrees. The average direction is
west, five.degrees south *.

No. 2. The second specimen is of small size, but is well chat
racterised, differing in no essential point from the last. It ap-
pears on a space of only two or three square yards, close to the
road side, at the remains of an old quarry, called the Maiden
Craig, about two hundred yards west of Craigleith, and oppo-
site to the lodge of Ravelstone House. This rock, which is of
sandstone like the last, has also a tail, interrupted, as mentioned
above, very distinctly by the diluvian excavation on the west of
Craigleith.

* Since this paper went to press, the valuable specimen here mentioned has
been almost entirely concealed by the mettle of a road thrown upon it. The
rock, however, remains entire, and may be cleared by any future observer.

Vox. VII. Aa No. 3.

186 ON THE REVOLUTIONS:

No. 3. The third is within the court of the old farm yard-of
Ravelstone. The greatest part of this court consists of a rock
entirely bare, and nearly horizontal; the whole surface of
which exhibits the dressings in the most distinct manner, be-
ing entirely composed of furrows, some of which are of a rh
size.

No. 4. The fourth specimen occurs near the foot of Camden
phine Hill, upon an old quarry, called the Well Craig, within
two or three hundred paces, bearing east 25° south of the
old castle of Craigcrook. It presents the dressing very di-
stinctly, and, like the two first specimens, upon a sata sloping
rapidly to the south.

These specimens are all upon sandstone.. The ‘remaining -
cases belong to whinstone, which, as has been said, occupies.
the upper part of Corstorphine Hill, sloping to the west. The
ridge of the hill lies north and south, with an inclination of
about twenty degrees west of north. It therefore meets our
supposed westerly stream nearly at right angles. The ridge,
as seen from Edinburgh, is very much. serrated, being cut.
across by small ravines; and upon the north, after the ge-
neral mass has sunk below the neighbouring country, the.
whinstone makes its appearance in various elevated masses in.
Barnton Park, lying in the prolongation to the northward of
the longitudinal line; the most northerly of these elevations,
which comes within forty or fifty yards of the old house of
Barnton, rising not. more than six or eight feet.above the turf.
These rocks, all of which, like the hill itself, present a slo--
ping face to the west, exhibit, upon that face, all the large di-
luvian features already described : the retundity, together with
the grooves and scoopings; but none of the scratches, or other
small features, are to be seen. . The character, however, of the
general operation is so well shewn, that the bearings of the

stream

pose

OF THE EARTH'S SURFACE. 187

stream are distinctly marked, and agree with those already ob-
served.

The ridge of the hill is about a mile and a half in length,
and rises in the middle to a height, according to the map, of
four hundred and seventy feet from the sea, perhaps three hun-
dred from its base. Along the summit, which is everywhere
planted, the rock is seen bare very frequently, in the midst of
the young woods, and often shews itself also in the ad-
joining fields. Among these rocks, which I have examined
again and again with care, so many examples occur, similar to
those just described in Barnton Park, that the hill itself may
be looked upon as one specimen illustrative of this import-
ant truth, in so far as the great features are concerned. In
the following ten specimens, chosen on that same ground, the
minuter indications of abrasion are also visible.

No. 5. In a place called Craighouse, upon the south side of
the Queensferry Road, opposite to Barnton Park, and between
it and the main hill, a mass of whinstone occurs, making part
‘of the same longitudinal line. It was formerly worked as a
quarry, for the purpose of paving and road-making, and is
now clothed with young wood. In its highest point it ex-
hibits all the large features of diluvian action, but none of
the small ones. These, however, it appears, have been de-
faced by the action of the weather; for, on removing the
young wood and soil from a surface of about twenty yards by
thirty of the lower part immediately adjoining, I have disco-
vered them in full perfection. Not only the grooves and
scoopings make their appearance, but the surface is seen, when
drenched with water, to be entirely covered with longitudinal
dressings, as already described, in speaking of the specimens
on sandstone. Where a rent has occurred at all in the direc-
tion of the current, it has guided the formation of a groove,

Aa 2? the

188 ON THE REVOLUTIONS:

the zig-zag form of the rent being softened off into a waving
hollow of uniform breadth, highly characteristic of the violent
action of a stream vested with the power of grinding. It is
remarkable, too, in more than one of these grooves, that at
their Eastern extremity, after maintaining an equal wideness
throughout, they suddenly spread to right and left, and lose their
form. These grooves are three or four feet in length, by four
or five inches in breadth. When arent has occurred at right
angles to the current, the rock has been ground across it, with-.
out visible modification of the action.

No. 6. From Craighouse Quarry (following the road which
leads to Corstorphine along the western face of the hill, and
passes on the east side of Clermiston) we arrive at a ruined cot-
tage, on the left hand, at the mouth of a little ravine which here
crosses the main ridge, and is called the Glen of Nortli
Clermiston. Close to the read, immediately upon the north side
of the ruined cottage, and within the wall which encloses the
wood, the whinstone almost bare, presents to view a continued
series of parallel grooves, one of which is twenty paces in length,
and others more. The hollows. of these: grooves are filled with
moss and earth, which, being removed, and the rock drenched’
with water, a set of furrows shew themselves perfectly well’
characterised, having the same bearings with those of the other
specimens, so-as to lie quite at right angles with the longitudi-
nal direction of the hill. This situation must be at least one
_ hundred feet perpendicular above Craighouse.

No. 7: About two hundred yards farther to the south, below
the road, stands a group of cottages, comprehended under the
same name of North Clermiston. Opposite to these, and
above the road, is a. barren space which has been the seat of
former quarries. Here several rocks are visibly dressed with:
the large diluvian features ; and at one spot, just twenty-six

paces.

OF THE EARTH'S SURFACE. 189

paces north-east from the nearest house, a fine set of furrows
occur, having the direction west 10° south. Continuing along
the same road, after passing through a young wood, we ar-
rive at the farm-house of Mid» Clermiston, lying below the
road upon the westward. Two sets of enclosures occupy the
space above the road, between it and the young wood, which
covers the summit of the ridge; the most northerly of these,
called the North Hill Park, contains two very interesting spe-
cimens, both: situated upon the upper side of the field, and
close to the-wood.

No. 8. Near the middle of the upper side. Here'a space of —
several yards square has here been laid bare by my former ope-
rations, and furrows and diluvian dressings are most distinctly
visible, indicating. a direction from west 10° south. One
small set, consisting of four or five parallel scratches, produced
probably by one. stone, cut the rest at an.angle of five or six
degrees, indicating west 5° south. -

No. 9. In the same field, and also close to the wood, about
thirty or forty paces towards:the- south, another specimen. of
the same kind occurs very well characterised.’

No. 10.. Immediately.adjoining:to this last-mentioned: field,
on the south of it, lies another irregular field, called the
North Mid-hill-park. From the middle and upper part of this
field, a path. leads up to. the summit. of the: hill, in a di-
rection nearly due east.. This path crosses an open: and
nearly bare space, in the midst of. the wood, at: the dis-
tance of about fifty paces from the ruins of the signal-house
on the summit. This space is-of about half an acre in extent,
and: so bare, that no trees have grown upon it. The rock has
here stood up in parallel tables, as is not unusual with whin-
stone, running nearly east and west; these have been com-
pletely rounded, as I conceive, by the current, and shew the

large

190 ON THE REVOLUTIONS

large features of dressing very distinctly ; the scoopings, in
particular, are very well debacky the small features have been
mostly defaced by the action of the air, but the removal of the
turf has brought some of them very well into view. These
agree with the grooves in the general indication of west 10°
south. In several places where a rent has occurred in the di-
rection of the stream, it has been excavated into the form of a
waving groove, as already seen in No. 5 p

No. 11. At the summit, a signal post had once been placed,
and the house used for that purpose, remains in a state of ruin *.
The rock of the summit (eight feet south-east from the south-
east corner of the house) is dressed with some diluvian furrows,
denoting west 10° south, as I found by clearing away some of
the turf. ene

The ridge of the hill stretching to the south, shews every-
where the same general character, by the rounding of —
denoting the action from the west.

No. 12..In a field called the South Midchillopark; in the
te of Mid Clermiston, in the south-east corner of the —
is a fine specimen, indicating west 5 south.

No. 13. The rock on which the summer-house of Ravelstone
stands (the Stone View, as it is called by the country people)
though completely exposed to the weather, shews some de-
cided furrows. It forms the summit of the southern part of
the ridge, and is only a few feet lower than the highest
point. From it the scenes No.1. No. 3. and No.4. are still
distinctly visible.

No. 14. In a pasture-field facing to the south, called the
Sheep, Park, belonging to cigs (0 Hill house, and imme-

diately

* Since this paper was read, the signal-house has been removed, and its foun-
dation only is now visible.

OF THE EARTH'S SURFACE: 19]

diately above it, is a good specimen, shewing the small features
of the dressing; the direction of which agrees with that of
the rest on this hill. This specimen lies contiguous to the
fence, on the south side of the field, at the distance of, forty-nine
paces west from a wicket, close to some cottages...

No. 15. Close to the: bottom. of the hill, on the south-east,
decain is a specimen, in fine condition, near to the avenue lead-
ing to, Belmont. As we go up this ayenue, in a direction
nearly due north, we leave two. fields upon the right hand.
The specimen here alluded to lies in the second or uppermost
of these fields ; being the same in which.a whinstone quarry is
now worked. The specimen lies near to the south-west cor-
ner of that field, being forty paces distant from the wall on the
west, and forty also from.that on the south. It presents one
of the most perfect and complete:examples I have met with,
of a groove, with a set of scoopings. corresponding alternately
to each other in opposite sides of it, and some of the obtuse
angled ridges in the highest perfection: . The whinstone is also
very distinctly dressed with the small features, which lie hori-
zontally, and follow some wavings of the groove: their general

- direction is like that of all the rest, with slight variations on

each side, of ten degrees south of north; at the same time, it
is worthy of notice, that the surface of the ground declines ra-
pidly from north to. south...

I have thus. pointed out fifteen specimens, within a circle
two miles in. diameter, surrounding Corstorphine Hill, each
exhibiting both the large and rem small features which in--

dicate the action of water flowing with violence along the

surface,

192 “ON THE REVOLUTIONS

surface, and carrying large blocks of stone along with it. The

number of examples concurring in the same indications of di-
rection, might easily have been greatly augmented, as any person
will see who examines the summit and western face of this hill;
but I have judged that number to be already sufficiently great.
I have taken care to denote each spot alluded to, in a manner so
particular, that it might easily be found at this moment: I say
at this moment, because, as is well known to every geologist,
nothing is more precarious than the existence of such specimens,
they being liable perpetually to be overgrown with vegetation,
or covered with rubbish, or perhaps completely annihilated by
the progress of the same operations which brought them into
view. These specimens are by no means all equally interesting.
Some of them are brought forward as simple indications of di-
rection, and owe their value to the force which the argument
derives from the concurrence of such a number of results.
Those which are deserving of notice on their own account, are
Nos. 5, 8, 10, & 15.

By considering together four or five of these examples,
which lie at a small horizontal distance from each other, we
shall be led to a conclusion which could not be deduced from
any one of them singly. I have said, that close to the summit
of the hill upon the west, an extensive space (No. 10.) of
rock occurs nearly bare, displaying a succession of parallel
grooves, pointing in the direction of the supposed stream,
and upon which some of the minute dressings also are ap-
parent. On examining this spot, two members of this Socie-
ty, whose ideas on this subject are hostile to mine, immediate-
ly remarked, that the appearance reminded them of what they
had seen in Arran, in the bed of the Garvalt, where the gra-
nite has been dressed by that torrent ; and they alleged as a con-

sequence, that the phenomenon was reduced to a common event.
I

we. eS - 2

|

OF THE EARTH'S SURFACE. 193

I beg leave, in the first place, to avail myself of this testi-
mony, in proof of the fact, that a stream, at least equal in force
to the Garvalt, has, at one period, flowed. over the rock at the
summit of Corstorphine Hill.

It now remains a question of importance to say, from what
source such a stream could have flowed, and how so much wa-
ter could be collected. The spot under consideration, is not
above twenty feet perpendicular below the extreme summit, so
that the heaviest thunder shower, could scarcely produce there
a sensible run of water; and if such a run were produced, it
would have nothing to carry, the whole consisting of one hard
and firm rock. The dressing is of large extent in itself, as the
bare rock shews, and it is also connected, more or less intimately,
with the dressed spots on the western face, Nos. 6, 7, 8, 9,12, &
14., so that a stream of considerable breadth as well as power
ai be required to fulfil the conditions of the case. The diffi-
culty is rendered more pressing still by two cases already men-
tioned; one at No. 11., and the other at No. 13., in both of
which cases the rock is visibly dressed, in a spot which con-
stitutes the local summit; the last of these, No 13. being the
-actual summit of this hill, and the highest point within the dis-
tance of many miles ; and the other being separated from any
higher ground by ravines, so that, in the present state of things,
no water could flow towards either of them.

The only explanation that could be given of these facts, by
means of the diurnal agents alone, must be obtained by
going back (as has been done in a theory discussed in an ear-
ly part of this paper), to some very remote period, when this
hill was much higher, and more extensive than at present, and
when a stream equal to the Garvalt could be collected above
those spots, and could run over them, so as to produce the
dressings under consideration ; and, by supposing, that in sub-

Vou. VII. Bb sequent

194 ON THE REVOLUTIONS >

sequent intervening ages, as in the hypothesis alluded to, all
this additional mass of elevation and extent had been removed:
by the perpetual corrosion of diurnal actions.

This hypothesis might be maintained as within the limits of
mere possibility, if all these dressings lay on one side of the
hill, as this imaginary additional height might be carried to the
opposite side. But as they occur equally on both sides of it,
either upon the hill itself, or very near to its base, that hypo-
thesis seems to be done away, as applicable to a part only of
the phenomena *. |

To

* It has also been alleged, admitting these dressings to have been the work of
flowing water, that the action may have taken place at the bottom of the sea,
and that the rock has since been elevated into its present position. Subscribing,
as I do most heartily, to the doctrine of elevation, as advanced by Dr Hurron,.
I am far from denying, that the very ease here supposed, may frequently have
happened ; I even conceive that it must have occurred occasionally. I should not,
therefore, object to this explanation of a dressed rock, that stood single in an ex-
tensive district. But that is by no means the case in the present instance: the
phenomenon is far from single; it is surrounded, on the contrary, by facts, and
classes of facts, calling for an explanation. This is afforded, if I do not deceive
myself, by the hypothesis advanced in this paper. But the explanation just
alluded to, would account for the dressed rock alone, and would be altogether
_ inapplicable to the other classes of phenomena; by such a partial solution, we
should therefore lose all the advantage derived in the theory proposed, from the
mutual light which the large features and the small ones have thrown upon each
other. ict
This explanation, too, would require no less an effort of imagination. than
ours; in, fact, the two suppositions do not differ as to the magnitude of the exer-
tion employed, but only as to the place of its original action, which we have
conceived to lie somewhere to the westward. An elevation such as would carry
this distriet from the bottom ef the ocean into its present position, could not fail,
(as we have endeavoured to prove in the first part of this paper), to be per-
formed by starts, and consequently to. produce waves, If the whole elevation
took place at once, it would be of magnitude amply, sufficient to fulfil, in some
other quarter, all the conditions of our hy pothesis, ;

It

OF THE EARTH'S SURFACE. 195

' To account for these dressings, therefore, we must call in the
assistance of some extraordinary agent; and this assistance is
at hand in the stream flowing from the west, the existence of
which we have been led to imagine by the parallel ridges and
tails which occur in this district. For the form, situation, and
direction of these dressings are such, as a belief in the reality of
that stream would lead us to look for. The mere arrangement
of ridges stretching east and west, leaves it in doubt from
which of these two opposite points the stream flowed ; but the
circumstance of the long depositions or tails parallel to these
ridges and dressings, which occur upon the eastern side of ob-
stacles, such as the rock of Edinburgh Castle, entirely removes
that ambiguity, and proves that the stream must have flowed
from the westward.

The grinders must then have been forced to move upwards

along the westerly face of Corstorphine Hill, and in that mode
Bb 2 their

It might also be alleged, that the elevation was performed only in part, when
the dressings took place ; and that a further rise had carried the mass, on a sub-
sequent occasion, to where it now stands; but nothing here seems to justify such
an intermediate supposition. All the diluvian facts in this neighbourhood, that
have come under my observation, concur in denoting one inundation overwhelm-
ing the solid mass of this district, which had been elevated into its present posi-
tion by some still more ancient revolution of the same sort; this inundation be-
ing the last catastrophe to which it has been exposed.

Having endeavoured to illustrate the appearance of the dressed surfaces, by re-
ferring to abraded rocks in the beds of rivers, I find that some gentlemen, who
had heard but a partial statement of my views, conceived it to be part of my sup-
position, that these dressings, like those in a river, were produced by water act-

ing for a long time. But this is by no means my view; my theoretical notions

limit the action upon the hill under examination, to the passage of a single
wave, embracing a period of time that could only be expressed in minutes ,; but
during that short time, I conceive the water to have been urged forward with
such force, and to have carried with it so many powerful agents, that it has pro-
duced effects equal to the work of ages under other circumstances.

196 ON THE REVOLUTIONS

their action upon the rock would be most powerful, provided
they were driven forward by sufficient force; the horizontal
motion thus urging each stone against the object to be ground;
(by an action similar to that which impels forward the chisel of
a mason, dressing the surface of a stone, which acts in the
direction of the axis of the chisel, forming an angle with the
surface upon which it acts), whereas, if the declivity lay the
opposite way, that same horizontal force would tend imme-
diately to draw away the grinder, and prevent its action. We
observe, accordingly, that though furrows or dressings do occur
at a little distance to the eastward of the base, upon elevations
presenting a western aspect, or lying flat, none such are any
where to be found on a surface of rock inclining to the east.

It is further remarkable, how little the direction of this ac-
tion has been disturbed by local circumstances. Thus, the
furrows in No. 6. follow the medium course right up the hill
though close to the ravine on the south, and though, upon the
other hand, at the distance of about two or three hundred
yards from the abrupt termination of’ the hill itself. This.
seems to prove, not only that the stream flowed over Corstor-
phine Hill, but that it flowed over it with a great depth ; for
had the stream done no more than just cover the summit, its
course must have locally obeyed the inclination of these sur-
faces. To pass along and disregard them entirely, seems to
denote a great superiority of depth ; and in calling it double,
we probably do. not exceed what is necessary. We have seen
enough, however, to justify my assertion, that the stream must
have been incomparably superior in magnitude to the Nile or
the Ganges, since even the ont AS Hill, occurring in the
course of these. mighty streams, must have completely deranr

ged their « course:
This

OF THE EARTH'S SURFACE. 197

This hill is stated to be four hundred and seventy feet:
above the sea. If we consider our stream as double the
depth, or one thousand feet, we shall probably not go beyond.
the truth. This height is nearly sixteen times the altitude of
the wave at Cadiz, which was sixty feet. The phenomena of
the Alps, though very imperfectiy known, indicate a magni-
tude double of this, by the mere position of the blocks on Ju-
ra, two thousand feet above the level of the Lake of Geneva.
While I thus, however, ascribe great magnitude to the dilu-
vian, torrent, Iam upon my guard against the excess of such
impressions, and the means have already occurred, as I shall
presently state, by which limits.are assigned even to this colos-
sal agent.

The geological truth supported by this concurrence of facts,
both vast and minute, is confirmed by innumerable circum-
stances, which present themselves to, view on all hands. in this
neighbourhood.

No. 16. At a place called Dickson’s Craig, upon the road to
Queensferry, about two or three hundred paces west of, Barn-
bougle Gate, is an example of whinstone rock dressed like
those, mentioned, having a sbrcobjon of three degrees south of
west.

No. 17. Another also occurs at the sandstone quarry. of
Redhall, at the distance of about two miles south of Corstor-
phine Hill, and occupying the side of the valley directly oppo-
site to it. This quarry is opened in one of the diluvian ridges,
and. the rock is covered by a bed of about twenty feet thick of
the blue clay, having various large blocks of whinstone suspend-
ed in it, one of which is not less than forty cubic feet. The
dressings point eight degrees-south of west.

No. 18. On the hill of Ravelrig, in a young. wood, near r the
eighth milestone from Edinburgh, on the road to Lanark, is a
fine

198 ‘ON THE REVOLUTIONS

fine specimen of dressed rock, which had been laid open by
the forming of the road, and is still visible ; the direction is
fifteen degrees south of west.

North Berwick Law in East Lothian, has a tail extending
towards the east ; it has likewise a specimen of whinstone rock
with the dressing upon it.

No.19. Another specimen occurs on a hill, which makes one of
a group of rocky eminences, to the southward of North Berwick
Law, upon one of which the ruined tower of Fenton stands. The
particular spot lies three or four hundred yards to the northward
of that tower, and close to the eastward of the little village of
Kingston. The rock presents to view furrows and scratches si-
milar to those above described on Corstorphine Hill, with the
additional circumstance, that the action of the stream has here
undergone a visible modification, by the prominent form of
some parts of the rock, in consequence of which the dressings
have, in some places, been turned, to the amount of five or six
degrees, out of the general direction ; which, however, they re-
sume gradually, in the course of ‘a few yards. A curvature is
thus produced, highly characteristic of the action of a torrent
from the west. The scoopings, too, meeting the general direc-
tion in obtuse angles, are indicated in the most striking man-
ner. The general direction, independently of these local dis-
turbances, agrees with that in the neighbourhood of Edin-
burgh, being from fifteen degrees south of West.

The same law prevails in other parts of East Lothian, as ap-
pears by examination of the ridges at Spott and Pinkerton,
which are very conspicuous objects from the great road be-
tween Edinburgh and Dunbar.

Observing the direction so constantly maintained in all this
district, which, at the same time, is that of the valley in which

the

OF THE EARTH'S SURFACE. 199

the estuary lies, I began to suspect that the production of
these effects may have been influenced by that valley; for
though the torrent had sufficient power to disregard Corstor-
phine Hill, it may have yielded in some degree to greater emi-
nences. If this law were established, we should be enabled
better to understand these operations, by having their stupen-
dous and unbounded magnitude reduced within tangible
limits. I became, therefore, anxious to examine the facts
which lay beyond the influence of this valley, where the indi-
cation of actions of a similar nature-might be found.. I recol-
lected having seen some ridges of a diluvian character in the
country immediately behind the promontory of Fast Castle in.
Berwickshire ; and as this constitutes one of the southern
flanks of the mouth of the estuary, | expected that some no-
velty in point of direction might here occur, and I was not
disappointed ; for I here met with a set of very distinct dilu-
vian ridges, called Lowry’s Knolls, the direction of which lies,
by true bearings, west 35° north; so that they form an
angle of no less than forty-five degrees with the general di-
rection of the estuary, such at least as it occurs in East and Mid
Lothian. As this new direction is assumed by the stream im-
mediately on finding itself at liberty, we must suppose that the
water, in this last-mentioned course, follows either the main di-
rection, or approaches nearer to it than it did in the estuary.
More observations are now much to be desired. With a view
to them, and in consequence of a recollection which led me to
suppose, that the Castle of Stirling was possessed of a diluvian
character, I have (since this paper was read) made a little ex-
cursion to that place.
I discovered, however, that the elongation from Stirling
Castle is entirely composed of solid whinstone, aihisceincnlthy
that

200 é ON: THE REVOLUTIONS

that its form has not been produced by a diluvian action. On
the other hand, I found myself surrounded by a ‘set of
ridges of alluvial matter. possessing a true diluvian character,
and several rocks presented themselves, having the larger fea-
tures. What gave a peculiar interest to these facts was, that
these features agreed with the ridges, in indicating a direction
between west and north, or east and south ; that is to say, quite
different from that near Edinburgh, but nearly agreeing with
what I had observed in the lower extremity of the Frith of
Forth. After considerable search, I discovered a rock of
sandstone in ‘Torwood, about six miles on this side of Stirling,
possessing the diluvian dressing in the highest perfection.
This rock is visible upon the south side of the road, just one
hundred paces west of Torwood turnpike-gate ; and the dress-
ing is most conspicuous close to this, in the neighbouring
wood, on the surface of a rock, some square yards of which I
laid bare. The direction of this dressing confirms what in a
great measure I had inferred from the large features, and from
the ridges. Its direction indicates no less than fifty degrees
north of west, or south of east, and thus differs very widely
from that near Edinburgh, going still farther to the north-
ward than what I had observed at the mouth of the Frith of
Forth. It has a considerable agreement, however, with this
last, and seems to favour the idea just suggested, that the di-
rection in the neighbourhood of Edinburgh may have been oc-
casioned by the local influence of the estuary, since the direc-
tion of the stream before entering it, and after quitting it, is
nearly from north-west to south-east. This influence upon the
direction of the stream, and on the deposition of loose matters,
seems to bear an analogy to that which is exerted, on a small
scale, in the abrasion of solid rocks, as seen on the ridge of
Corstorphine Hill and at Kingston.

I

OF THE EARTH'S SURFACE. 201

I have witnessed another set of facts, of which I can, as yet,
produce but one example. The district along which the road
passes from Edinburgh to Dumfries, in the neighbourhood of
Noblehouse, exhibits a series of low hills, possessing the cha-
racteristic forms of craig and tail, which belong to those in
the neighbourhood of Edinburgh, but such as to indicate the
action of a stream flowing from the south-west. This is a high
district compared to that of Edinburgh, and the waters may
here be supposed in some measure to flow towards the estuary
of the Frith of Forth.

These changes shew the importance of more extensive ob-
servations. At the same time, the concurrence of various
indications, in pointing out one common direction at each
place, seems to denote the influence of some general cause,
and authorises a hope that the facts, when properly col-
lected, will enable us to trace the general direction, and per-
haps the origin, of this important agent.

Character of the Western District.

Another district of Scotland, which circumstances have led
me to traverse in various directions, presents to view a state of
things as different from those which have lately been described
as could well be conceived. I mean, the south-west of Scot-
land, comprehending the stewartry of Kirkcudbright, the shires
of Galloway and Dumfries, with part of Ayrshire, on one hand,
and part of Cumberland on the other.

Vou. VIL Ce In

202 ON THE REVOLUTIONS .

In that district, the straight and parallel ridges, so universal
in this neighbourhood, and the forms of craig and tail, such as
that of Edinburgh Castle, nowhere occur. The same assem-
blage of substances assume a different form, and present to
view a perpetual succession of knolls, equally round at both
extremities. This. arrangement is conspicuous in the neigh-
-bourhood of Gilsland, which is surrounded with knolls of this
description. It was there that a theory occurred to me, to ac-
count for the contrast of the opposite side of our island, which
I have never since had occasion to alter, having found that it
gained ground by every new observation. I have, in particu-
lar, observed these forms to prevail exclusively in the valleys
of Carlinwork, of Dumfries, and of Kirkcudbright. I imagined,
that the diluvian wave had flowed at some remote period from
a westerly or north-westerly direction, and had broke over our
island ; that its magnitude, though perhaps far short of the al-.
pine stream, had been such, that a great body of its water
crossing the ridge of country which separates the two coasts,
overwhelmed the district in the neighbourhood of this city, dis-
charging itself into the German Ocean. But that another por-
tion of the wave, being retained by that ridge of country, and
being left to follow the impulse of gravitation, when the supe-
rior water flowed on, had returned again upon the countries
which it had just crossed, like the back-draught of a common
wave. By watching the operations of a high sea, breaking upon ~
a rapidly shelving beach, coyered with coarse gravel, we may
1orm some judgment as to the influence of such a back-draught; .
the sound produced by the blocks of stone grinding upon each
other, as the wave retires, conveys a strong idea of the corro-
sion which must take place in such circumstances. Our East-
ern coast would thus be exposed to. a. single diluvian action,
syhereas that. on the West would undergo two in succession,

and.

OF THE EARTH'S SURFACE. 203

and nearly in opposite directions; and the analogy of the
events at Lisbon and at Lima, leads us to suppose that seve-
ral similar actions may have taken place in succession. At Lis-
bon, five waves in succession followed the first. In the present
case, the influence of all but the first, would probably be
confined to the western side; or if any of the rest possessed
elevation sufficient to surmount the ridge, still the portion of
its water which passed over, and that which returned, would
each follow the same course with the corresponding portions
of the first wave. And there is every reason to believe, that
the action would be repeated. often upon the side facing the

inundation. ‘2
The facts seem to correspond with this theory. We have
endeavoured to account for the peculiar form of craig and tail,
and for the parallel ridges, so frequent on the eastern coast, by
the influence of a single powerful stream, the effects of which
have since undergone no modification, but from the feeble exer-
tions of diurnal causes ; whereas, on the other side of the island,
the same set of forms, which we may conceive to have been gene-
rated by the first direct impulse, being assailed in new direc-
tions, by other forces, less powerful, but frequently repeat-
ed, we have reason to expect that these assemblages, compo-
sed of loose, and newly deposited materials, would undergo great
changes, and that the ridges would be broken down into succes-
sions of knolls ; that the crags would be filled up, so as to equa-
lise the declivity on all hands; in short, that such a scene as
the west coast of Scotland presents to view, would be the re-
sult. The circumstances of detail concur with the observa-
tions founded. on the large features; at least they by no means
contradict them. In the west, many striking instances occur,
of rocks dressed with grooves and furrows, as already described
in the east: but there is this material difference between the
; Cre 2 “4 two

204 ON THE REVOLUTIONS

two sets,—that whereas in the east, these furrows have preser-
ved the same direction, those on the west follow directions so
irregular, as to baffle all arrangement, or, if any such can be
traced, it is found to be entirely local, and to depend upon the
course of the valleys. in the immediate neighbourhood. In
some places in the west, as near Moffat, I have met with vesti-
ges of ridges; but, on close inspection, I found them rounded off
at both ends. Even these, however, occur but very rarely, and
are to be expected, under the hypothesis here laid down, ac-
cording to which, it is reasonable to suppose, that the effects of’
the first impulse should not be always completely done away
by those which followed. Also the direction of hills in the.
west, may occasionally have been such as to produce conspi-
ring effects with those of the first action.

In the neighbourhood of the Bay of Kirkcudbright, I have:
seen two specimens of rock, dressed with furrows, very well-
characterised, and both indicating a direction from the north ;
one near the porter’s lodge connected with the House of Bal-
mae; the other upon a rock within high water-mark, upon
the south side of St Mary’s Isle. But the neighbouring country
has no corresponding character, all the loose assemblages being
arranged in. knolls.

On the island in Loch Doon, upon the confines of Ayrshire,
and the stewartry of Kirkcudbright, the dressing of the rock is
peculiarly interesting. The island is of granite, near its junc-
tion with the strata; and the granite contains many sharp an-
gular fragments of'killas. Where the rock has undergone the
diluvian dressing, the contrast of the two substances is beauti-
fully displayed, the granite being of a light colour, and the kil-
las dark-blue.

By the action of the air, the granite has been decomposed’
at the surface, and has been corroded nearly to the depth of an

inch ;

OF THE FARTH’S SURFACE. 905

inch ; but the killas has resisted that action completely, and its
fragments stand above the level of the corroded granite, pre-
senting to view the diluvian dressing unchanged. A curious
consequence has resulted from this circumstance: A fine white
clay, produced by the decomposition, was mistaken some years
ago for marl, and in order to obtain it, a tunnel was cut
through the rock, over which the water in its exit to the lake
had flowed. The level of the water having in this manner been
lowered several feet, a portion of the rock of the island is
brought into view, which had previously lain under water, and
which, in consequence of the exclusion of air, had not been de-
composed, nor had suffered any change, since it underwent the
diluvian dressing. ‘The consequence is, that in the upper part
of the island, we see the granite corroded, and the killas en-
tire, whereas, near the water’s edge, the surface of the rock
presents its diluvian dressing throughout; and the two sub-
stances are only distinguishable by their colour. We have
thus an interesting display of the influence of time; and the
circumstance suggests to me a mode, by which the antiquity
of these events may perhaps, in a certain degree, be ascertain-
ed, and of which some future observer may avail himself.
Had the tunnel been cut many centuries ago, at a known pe-
riod, and had the granite exposed by it to decomposition, un-
dergone a measurable corrosion, we should have been furnish-
ed, by instituting a comparison between the two corrosions,
with a chronometer, or a rational basis for calculating the anti-
quity of the diluvian event. The same view may be taken of
those blocks of granite in the valley of Monti, upon Saleve,
mentioned by Saussure, and alluded to in a former part of this

paper.
In the neighbourhood of Loch Doon, a set of very large,
loose, and rounded blocks of stone occur, which resemble those
to

206 © ON THE REVOLUTIONS

to which I have so often alluded in the valley of Geneva: the
largest of these is known by the name of the Carnwhaple-
stone. The appearance of the country induces me to imagine,
that they had been lifted out of the loch by some concentrated
force of the returning stream.

A number of large blocks of granite also occur on the hill,
at the Pass of Stanmore, in Cumberland, which I was at pains
to trace to their source, and found it to be a rock called the
Westledale Crag, which is a granite of the same quality with
them. .

A single block of granite, of four or five feet in diameter,
occurs in the street of Darlington.

The transportation of such blocks does not seem to have
happened very frequently in Great Britain, at least in those
parts of it with which I am acquainted ; and where they occur,
in the neighbourhood of Edinburgh, they are generally embed-
ded in the blue diluvian clay. That water, however, in the
circumstances which we have supposed, does possess the power
of transporting very large blocks, we learn by a direct proof,
in what was done at Cadiz by the wave which accompanied the
earthquake in 1755. It broke down a large piece of the ram-
part, and carried solid masses of masonry, of eight or ten tons
weight, to the distance of forty or fifty yards, as we learn by
the account of Mr B. Bewicx, (Philosophical Transactions,
vol. xLIx.)

THE

a hs 2

_—_— ee _—

— |

OF THE EARTH'S SURFACE. 207

Tue observations I have made on this diluvian subject, has
been confined to a small range of country, comprehended be-
tween our two seas, because it is only of that small range that
I can speak with any tolerable certainty ; but I have reason to
believe, that other members of this Society, possessed of every
requisite advantage, are ready to take up this curious subject,
and to pursue it with vigour. On that account, I have the less
scruple in bringing forward views, that may to many appear
extravagant, since there is reason to expect, that whatever er-
rors I may have committed will soon be rectified. .

I trust also, that the facts brought forward in this paper, are
susceptible of an extensive application, and that they furnish ;
the means of ascertaining the direction of diluvian inundations .
across the great continents. By a comparison of directions, .
- these tremendous agents may be traced to their source.. The
native place of the granite blocks, mentioned in the Ist part of
this paper as occurring on the shores of the Baltic, and also of”
those on Mount Jura, may thus be discovered. Ifboth sets came
from Mont Blanc, we may expect to find between it and the
Baltic Sea a system of crag and tail like that in the neighbour-
hood of Edinburgh. Ifthe Prussian blocks came from another -
quarter, the circumstance will soon speak for itself, and the
question will probably be decided by the first traveller ac- .
quainted with these ideas; who passes; ever so rapidly, through
those countries.

_ In the same manner, we may expect to see light thrown on
the histery and circumstances of that tremendous event alrea-

dy

208 ON THE REVOLUTIONS

dy alluded to, as indicated by the observations of Patias; by
which it appears that the skeletons, and even carcases of great
animals and fish, natives of the torrid zone, are found embed-
ded in the soil along the banks of the great Russian rivers, and
buried in the earth, in the frozen regions along the shores of
the North Seas, where thaw never penetrates more than a yard
below the surface.

The series of inquiries, the result of which I have laid be-
fore the Society in the course of this season, was first sug-_
gested to me by the vertical rents, filled with congealed lava,
which are visible on the craggy face of Somma, the ancient
part of Mount Vesuvius. They exhibit a clear view of those
restraints under which the eruptive efforts of volcanoes are
held in quiet times, and which are occasionally surmounted ;
and this circumstance, transferred by analogy to the plutonic
regions, has afforded, by means of the forcible intrusion of li-
quid granite, a satisfactory account of the convoluted structure
of the strata of killas, when in a semifluid and flexible state ;
the convolutions thus formed, furnishing an easy explanation
ef vertical stratification.

The same restraint, occasionally overcome, has explained
the protrusion of whinstone among the secondary strata, some-
times in vast beds parallel to them, and sometimes in huge
amorphous masses. The restraint exerted by these inflexible
obstacles, being surmountable only by acts of violence, I have
concluded that the elevations, both volcanic and plutonic,
must have been accompanied by a succession of powerful
starts; and great part of these operations taking place un-
der the sea, that enormous waves must have been thus pro-
duced. In this manner, a satisfactory account has been furnished
of earthquakes, and of their attendant waves, as well as of the
overwhelming inundations alluded to in this paper, the reality

of

OF THE EARTH'S SURFACE. 209

of which is evinced, as has been shewn, by the concurrence of
a three-fold set of facts, surrounding us in this neighbourhood.
1. The distribution of loose matters in tails and ridges, on
this side of the Island, and in knolls on the West. 2, The
grooves and scoopings, and obtuse-angled ridges, occurring
on the surface of rocks of every description ; and, lastly, the
scratches and other minute features of abrasion, which are
found to accompany the large features, where the rock has
been . protected from injury.. All these events have been
shewn to arise, as natural COREG AT CEs: out of the Huttonian
Theory. | |

As another consequence of these: sided L have also: ‘brought
forward the formation of valleys of all sorts.. I have imputed
the detachment of mountains, and the formation of islands, as
well as of promontories and arms of the sea, to-circumstances
which could not fail to take place in the forcible elevation of
stiff and frangible masses, performed. by a ane sisk of local
efforts from beneath, urged by irresistible power *

I have furnished a theory of the formation of lakes, which
does not seem hitherto to have been accomplished in a satis-

factory manner, by any other hypothesis. One class, belong-
Vox. VIL. ing.

* Since the first part of this paper was printed, a very familiar circumstance
has presented itself, which affords a clear illustration of this great natural ope-
ration. When a mason is preparing common lime for building, he lays the burnt
limestone in a heap, and throws water upon it; after this, some time elapses be-
fore any action is visible, before the lime, as.it is said, begins to fall; in this in-
terval the sand, which is to be mixed with the lime, is thrown upon the heap, so
as to cover it completely, and the surface is made smooth and uniform by re-
peated blows of the flat of a spade. Soon after this, a heave takes place from
within ; the lime swelling, raises up the sand, and divides it by numberless rents,
which becoming wider and wider upwards, as the heave advances, a representa-
tion in miniature is produced, of an alpine district.

Bins 5 ae Nagy OI
. ® 2 ‘ Ti, 7
210 2 ON THE sa sil TC ae a

ing to solid rocks, I have derived from rents formed b sll ¥
lities of elevation, and the opening of rénts upwards. Another oF
class, formed in alluvial districts; has been traced to modifi-
cations performed. by various obstacles upon the depositions _
made by the great inundations alluded to. UHR SSO | ae
WS. 20 ¢71201, ie.goslage oxls on

In thus controverting some of the collateral opiltfonds of Dr
Hourron and Mr Prayram, I venture to-hope that my argu-
ments, which have been founded on their principles, and whi
have led me to acquiesce in their most general and important
conclusions, may tend less to weaken, than to confirm, the re-

sult of their immortal labours. NDA Mg
. : ‘
tai
7 od 4
a ? ‘ . f P
« me SPECIMENS. ~— |
- .
ra
& . :
ff
a
r
» se a
. . “* :
xy a
+ a

*
«
OF THE EARTH’S SURFACE. 211
ou : fs
i... <
a 4 SPECIMENS.
tHe = 8
No. 1. Craigleith ay from” rae UW. 5° Sto Eb? N.
_ 2, Maiden Craig, ——- sone W. 5° S.
3. Ravelstone old farm-yard, Wz. due.
4, Well Craig, near Craigcrook, W. 20° S.
5. Craighouse Quarry, Oe. SS.
6. North of ruin at Dean of North
Clerimston, @ * »*- 'W.10°S2
7. North-east of cottages there, W.10 S$.
8. Middle of the North Hill Park, W. 10° S.
9. South side of ditto, - W. 10° S.
10. Bare space west of summit, W. 10°S.
11. Summit of the hill, = W. 10°S.
12. South-east corner of South Mid-
Hill Park, - - RY 15° SS.

13.. Summer-house on second sum-.
ree mit, belonging to Ravelstone, _ W. 15° S...
14. Sheep. Park of. Corstorphine -

Hill House,: _ ~ WY. 3’ §
15. Below Murrayfield Quarry, east”

of Belmont, - W. 15° S.
16. Dickson’s Craig, Barnbugle, W. 3°S.-
17. Redhall, - = el. 8S
18. Ravelrig, - raw LP §.

19. Kingston, near North Berwick, W. 15° 8.

~~

Dd 2 VI

be

+g.
on
»

4s ig

Be ag

Pee

i

ee
a «

PLATE VI. Vol VIL page 222.

Fnad by Ie D.Lixars Bdint

pinpy sonra ya kg plus

“aT O BVI Hl

LL Sted SUP

Cae a eae ease f = {oer
en ae oe ee ee Fae, | e
Ce ee ‘ et eae oS /
oo Et i a OES ‘ . co = ere

oo Ree

| elarhredt ign

“ie om: &)
(vier eat Ab

Barn or ~
ne near ‘i

LUT SONT ANAL VL

~ SS -
WSs
- =

MYT 8 Y SULL,

“qty eS *

et Pan aaale| oak

: : : .. ‘ °

aS Jee ee ’ "
se = ss e
1 a: 4

MPT EONT TY M MQ bug

a a

TN et [=

TK PLL 0 ST A

yrrypg somup Aq posoarnig

-ZLINT OL,
aD =

TIE TNMLEIMOLSE

Da

OS pENpTO ds

Soe
NVTE |
LS ds 5

= = 3),
ee anni S a

ypredue og

Wt

=

\\

‘ AW

~

: i y es
ade

yn

AUTtOg py Ut eA
Aer TO gs

SOs

A
wer

RR

yr

as

4

34

“4

spon

“‘poomnaoog
F

A

gut!

nov

uu

ouere g PTO

pee]

LUT SL UPL,

.

as

ois:

Se

inc pil torre ah

pas

aval cen mete Se oe
eS

Sate GAB as ete LAG RS ins el as ite BOTS IOR

sa eS See

oy

i &
Ae ass Y

AW ed
wr Oy.
Deets

2

EN

VI. An Account of some Geological Facts observed in the Faroe
Islands. By Sir Grorce Stevart Mackenziz, Bart.
Pr. Pu. Ci. R. S. Eni. :

{Read Nov. 2. 1812.]

TCHE singular appearances which were presented to my
view by the Trap Rocks of Iceland, and the interest
which they excited, made me resolve, as soon as I had given
an account of that country to the public, to visit the Islands of
Faroe. This expedition was undertaken, for the purpose of
ascertaining, whether, in a Trap Country, where no traces of
external volcanoes existed, any thing similar to the peculiar
features of the rocks of Iceland was to be found. In the latter
country were discovered a series of rocks, lying above the beds
of Trap, which bore the most striking marks of igneous origin ;
in some instances having a perfect resemblance to ordinary
Trap, and in others to the common Lavas of the country.
The beds of Trap, and those above them, being separated by
mechanical depositions of Tuffa (Trap-Tuff), led me to the
conclusion, that the whole of the beds had been formed at the
bottom of the sea, by successive eruptions of a submarine vol-
cano.

214 GEOLOGICAL FACTS OBSERVED > -

eano. The results which I suppose may have attended a sub-.-
marine eruption at a great depth, will be quoted in the se-
quel. \ o

The following observations of Lannr, Ain Se the forma-.
tion of these islands, contributed essentially to confirm the de-
sire I felt to explore the country. It must be believed, that
this clergyman had possessed some previous knowledge of the
igneous theories. “ It would form,” says he, “ a.curious ob-
ject of research to inquire, in what manner the Faroe hills have.
been formed, and how they attained their present elevation ;
whether above or under water? Whether they owe their
height to volcanic explosions, which threw one stratum above
another, or whether these strata were deposited upon each —
other under the water, and were afterwards raised to their pre-.
sent situation by a volcanic eruption, or some elastic force pro-
duced by subterranean inflammation ; or whether these hills
have been formerly covered by the sea, which has since retired"
back, in consequence of some convulsion of nature * ?”

Again ; “ But in examining the bottoms of the hills along the
sea-coast, one will often discover indubitable.marks of colmaiiie
eruptions, or of some other convulsion: of nature, which has
acted a distinguished part in the formation of the singular phe-
nomena which here present themselves to the eye of the curi-
ous observer. It, is seen in many places close to the water’s
edge, that the matter of which the rock is formed has been. in
a state of fusion, and has become hard in. its, course. Some-
times this hardened matter is smooth, on the. surface, but. has
the appearance of the ice on a stream or rivulet, where the wa-
ter rises above the first crust, and, forms several strata, one
above the other ; but sometimes this hardened matter is rough,

| and.

* Lanpt, Translation, Lond. 1810, p. 5.

™... - ‘IN THE FAROE ISLANDS. 215

a ‘and full @icles and knobs, such as we may suppose would be
_seen in metal. first fused, and then cooled in water *.’
Sadie, Besides the desire natural to all travellers, to have a friend to
“partake their ‘labours and enjoyments, the particular object I
had in view, rendered it a matter of importance, that I, should
have a companion, of whose competency to judge upon the

/-
spot, of any new fact that might occur, there could be no doubt.

On proposing to him to take a share in the expedition, my
friend Mr Tuomas ALLAN, whose great experience in geological

- @ examination, and his intimate acquaintance with imdividual

minerals, eminently qualify him. for research, tpadily agreed. te
seep paly me.
The islands of Faroe, or North Faroe as they are: acura
_ called, are nearly midway between Shetland and Iceland; and
lie between the parallels of latitude 61° 20’ and 62° 251, extend-
ing north and south about seventy-five miles. The meridian
of the seventh degree of west longitude divides the group into
two nearly equal parts ; the extreme points of land on the east
and west sides including 1° 25’, or about forty miles. Besides
. a great many detached rocks, the islands are eighteen in num-

_ ber; the largest, viz. Stromoe and. Osteroe, being in the centre.
The extent of the former is twenty-eight miles long, and, on
an average, six miles broad ; that of the latter, about the same
breadth, and twenty-two miles long.

_ The general aspect of the country is mountainous and preci-
pitous ; and, while the lofty rocks which frown over the ocean,
inspire distrust in those who approach them for the first time,
many excellent harbours are to be found, where rate of any
size may ride securely.

» The principal place i is Thorshavn, situate on the east side
of Stromoe. It is a small town consisting of wooden build-

ings,

* ‘Lanpt, p.11.

oe “B® ; _ fF a ps

Cin gi x
216 # GEOLOGICAL FACTS OBSERYED © sae aby Se

into a oy and mine two very pS iene harbours.
country in the vicinity, though by no means flat
the greatest tract of comparatively low land to be n
in any of the islands ; but it is exceatt ingly bleak a d
There are, in a fae places, valleys of yee small extent ; the
separation of the mountains being for the most part narrow
glens, and, in many instances, merely the breadth of py oi
stream. oP z
The soil, in almost. sienipepart of the islands, is chie eae.
No trees are to be seen, excepting one or two stunted moun-
tain-ashes in the governor's garden. This deficiency of trees
may be attributed, perhaps, more to the wetness of the soil
than to the climate. The whole country abounds i in springs ;
no part of the soil being naturally dry, while, at the same time,
it is very shallow.
There are two lakes of considerable size in the island GP ¢
Vaagoe. One, called Sorvaags Vatn, is about three miles long,
and about half a mile broad. The waters of this lake approach
very near the coast, which is lofty and precipitous ; and, after a.
short course, fall into the sea, forming a magnificent cascade |
about eighty feet high. The other lake is on the north-west ~
side of the island, and is about a mile long, and a quarter of a
mile broad. It is not named on the chart, nor by Lanpr.
In Stromoe there are several small lakes, the most consider-
_ sable being that near the village of Leinum.
There are but few in Osteroe; the only one of note is .
that called Tofte Vatn, at the south-east end. ‘ :
The streams are in general merely brooks ; that which is- a
sues from the lake of Leinum being the only one which can ¢
be considered as a small river. ‘The variety of cascades which» ~ %
these streams form, is endless: and some of them, whe
swollen =

: a“ a ° -
: ae ial a )

= ih * IN THE -— ISLANDS. © 4 217
t fo en aes rain, are a | picturesque. Many of them
gil frommsugh a vast height, that they are completely disper-
i. ted into - fine spray } long before » they reach half-way down the
precipice £
{The mountains, present a variety of forms, but tend chiefly
to assume that of a cone at their summits, which are often very

, sharp and rugged. The Northern Islands, Kalsoe, Kunoe, Bor-
"—

~
-

doe, and Videroe, consist of long sharp ridges, the summits being
Porqken into many fantastic shapes. The highest land is in Stro-
a %. moe and Osteroe, which are separated by a narrow channel,
which in one place is scarcely a quarter of a mile bread.
The state of the weather prevented our ascending the highest
mountain, called "Skellingfell, in Stromoe: but we succeed-
ed in reaching the summit of one of the highest mountains
in Osteroe, called Slatturtind, near the village of Eyde. By
barometrical observation, this appeared to be 2825 feet above
the sea. Skellingfell * cannot ‘be less than 3000 feet high,
and is probably somewhat more. ~
The western coast of Stromoe presents an extent of twelve
miles of the most sublime rock-scenery that can be conceived.
_ Every part of the Faroe group has its romantic beauties ; and
’ there is scarcely a promontory which does not exhibit a scene
calculated to excite the most lively admiration. The general
‘elevation of the precipices on the west side of Stromoe, varies
from 1000 to 2000 feet. There is a cliff called Kodlen, form-
ing the north-west promontory of Osteroe, which did not strike
us so much by its elevation, (for it sunk far beneath the neigh-
bouring rocks of Stromoe), as by the circumstance of its being
+ exactly perpendicular. Mr Atran measured its height by
? L te Vou. VII. Ee means

woe .
w an

»

* The name of this mountain, and some other names, are variously spell.
- ed; but the mode adopted in this memoir conveys the pronunciation.

>.

w i» o* -~
= ae | - Per o "*
id es |
218 GEOLOGICAL FACTS OBSERVED . pe es
*
“means of a 4° lt was thus +” ta tian be 1134 fe
nip:
Greatly as our admiratio Ws excited | by ae & oe ea %
exterior of these islands, t eir internal oe fil:
mont power to arrest our tattentoht <n

* The Faroe Islands are ‘composed almost entirely of Tatts ?

~ most common characters of which are amygdal idal and por-
phyritic. Beds of coal. occur in Suderoe, and, it is ‘said, also i in
Myggenzes, neither of Scifth islands we could visit, on account of*
the unfavourable state _of | e weather, at the time we barere +s
about to make an attempt to land upon them. The beds of _
Trap are inclined at a small angle, abo 4 or 5°, and dip to-
wards the south-east *. Their thickens varies; in some, it is
but a few feet ; and Lanprt states that of some columnar beds,
which we did not teach) to be from 100 to 300.

The first striking resemblance between the rocks of Fa-.
roe and those of Iceland, We observed in the separation
of many of the beds of Trap by thin layers of Tuffa, re-
sembling red sandstone. In both. countries, this tuffa occurs
of a pba and of a yellowish colour ; and sometimes assumes
the small columnar form, and then it has a: tendency to the tex- >
ture of Wacke, In Faroe it occurs also of a green co-
lour f. -

» , “ The

bg

*
%

.

-* We had a view of Myggenes, near enough to distinguish that it was com-

posed of beds, which rose at an angle considerably greater. ~The coal is proba- 4

bly in the same position as that found in the ise of Skye, near Talisker, where ~
it occurs between beds of trap. } a c
+ I have preferred the term Tuffa to thet of Trap-tuff, because I wish to em- 4

ploy a generic term, and one that has no allusion to theory. T'rap-tuff x »
no doubt, used as generic by the Wernerians; but it is in reality a Spe Ne
cific term. It is a question whether the specific terms should be derived —

. from ~

= ca

» & Age e

* et Se

to a + e *
, -* ie DS PAIN THE PAROE ISLANDS. » t 219
. oo & ; i +
S rue rst example we had an opportunity of examining, of
t species es'of tuffa nse beds of which form so remark-

uture of Tecland, + was observed forming part of a very’

us rock on the : coast of the island of Vaagoe, call-
a1 ar We saw the same sort_ of 4 in different
aces ; sh aaa icularly at the bottom of the promontory called,

‘the basis, which variés | in, Hors respects, it may perhaps be best, when there
‘is ‘any uncertainty Yayal© describe both it and the ‘included masses; for pro-
lixity is, in every description, preferable to want of ‘perspicuity. Trap-tuff im-
‘plies, either that the basis is derived from Trap, or that the included masses are
Trap, or that both have the same origin. — Now, as the rock in question often
contains sandstone, and sometimes wood; and as in Tceland “and other volcanic
‘countries, it contains lava and other voleanic substances; the term Trap-tuff
conveys none of these important particulars. ‘Correctness seems, therefore, to
" demand some reform. I would propose that the basis should be understood ge-
~ nerally, as Professor Jameson has described it, to be “ rather a loose, spongy,
_"_ « clayey basis,” and that we should relinquish the term trap, and use, as a ge-

neral term, the word tuff, or the original and more harmonious Italian Tuffa, and

describe the included masses. Thus, in Iceland, I met with tuffa, the compo.

nent parts of which were so minute, that it resembled red sandstone ; tuffa inclu-

tuffa including masses of trap, lava, slags, and mineralized wood. Here the de-
scription appears to be absolutely necessary, to prevent misapprehension ; and in-
"stead of being at.all offensive, it affords perfect satisfaction: whereas, ware
? use for them all merely Trap-tuff, many important oo would be =
ted. ) 4
. Objections also arise to the term Cale-tuff, which may be 2 understood to Hoan
_ a calcareous basis, cementing together substances, the nature of which we are left
to imagine. The included masses, being sometimes, entirely calcareous, and
. sometimes heterogeneous, the term, by itself, conveys nothing satisfactory. For

jectionable, when qualified, as circumstances may ney Ma a description of
the basis and the included masses. t -

« hes

Niepen) in Stromoe. It may also be seen on the beach, near
4 the village, in Naalsoe. 8
“a ee ‘hs *, - e2 Ro The
Py yam ME I
» ‘from the basis ae included aa. 3 As it is not in any case:easy, I
‘may say possible, to d nine to what specific substance we ought to refer

ding rounded masses of trap, from a size very minute, to many feet in thickness ;
w@

- fragments connected by a solid basis, the ol ‘term breccia, seems to be unob-

" es ' : =

+ : ave

ed

«
220 Pa cnonoere at. FACTS OBSERVED © - ~

The Society ‘ill PS doubt collect thesfact which T “s
scribed, of the under-su rfaces of many 0 | the beds of ake
: Iceland, bearing unequivocal mafks of their having b een in’ a
state of fusion, of which the arious specimens in our ca-
binet. On “finding t the red separating the beds in Fa aroe,
ar expected fo meet w with some indications of héit'in that ‘coun-
een also; and T was not disappointed, though theif occur-
“rence was not so frequent in Faroe as in Iceland. Near.

2 are

Kirkeboe, we observed a considerable degree of roughness ”

on the J bottom ofa bed f rock, eee resembled s some
that éccurred ‘in Akkrefe Iceland uch, that the
specimens differ only in. ee of colour. At Kirkeboe,
such marks of fusion were in many places quite apparent 5

but I did not suc ed in my attempts: to procure a mass
of a size eullicientt to. Sahib, in a satisfactory manner, the ge-
neral feature which is so remarkable. The most ‘perfect: I
could pr ocure on a small scale, of that Slagginess which was so
conspicuous in “Iceland, was found on the ill of Leinum in
Stromoe. «I had to regret that heavy rain, and: the risk incur-
red in wandering among high precipices, while surrounded
by thick fog, pievented - ‘my ablehe this mountain so com-
pletely as I wished.”

But whatever degree of doubt might have been left on my
.mind by the appearances just described, it was entirely
dissipated “by a new ‘and most important fact, in rela-
tion to heat having operated»in the formation of trap,

nich first presented itself to our notice in the island of
Naalsoe, where almost every circumstance of importance
in “the geology of Faroe is to be seen, and where the great-
est variety of the indiv idual minerals which oecur in trap
are to ‘be found. This _island “Hes opposite to Thorshavn,
% being separated from Stromoe | by a channel about five miles
broad. ~ It, consists of one mountain, rising to an elevation of

a* al Me % 1500

5

GhoLogr ar Fanox. PLATE I

a ee

{
i
:
;
4
e.
ie
\
p
a
'
y
€i
§ ‘
$e |
re! ’
Ee

GeoL00¥ OF L4AROB LLATE 2- *

Ys vy
v sal
* S ° ,
ms a! be #, IN THE FAROE ISLANDS. oot
. _* * :

» >: 1500 feet ; and receives its name, which signifies Needle Island,
ain from a perforation in a rock at the south end, thought to re-
) ». semble the eye of a needle. ~

: “The surfaces of many lavas which I passed over in Iceland,

= were not unlike coils of rope, or crumpled cloth; an appear-

EF ince which we should expect to be assumed by any viscid

* > matter in motion. On our first visit to the Island of Naalsoe,

_» we observed the surface of a bed of amygdaloid, which had

been exposed to a considerable extent by the removal of the

we bed above, exhibiting an exact picture of the lavas I had seen

in Iceland. At. first sight, this discovery forced instanta-

* neous conviction on the minds of those who were with me, none

of whom had ever seen lava, that heat must have caused the

appearance before us. We brought away a number of speci-

_. .» mens, which are now before the Society, and which speak a
F language not to be misunderstood. (See Plate I.)

We afterwards discovered varied examples of this crump-
led surface in different parts. of the country.. In the vici-
nity of Eyde in Osteroe, there were many instances, in
which the matter appeared, as if, in a viscid state of fusion,
it had flowed and spread itself out. Of this a specimen is be-
fore the Society, sufficient to explain the fact, though it does
not afford so good a display as we could have wished: our at-

7 _tempts to raise large masses entire having failed. (See
Plate IL) We found that one bed was exactly moulded
on another, and had every appearance of the lower one
having become hard before the next had flowed over it.
This “was observed at various elevations. Near Waii in
Bordoe, we saw several examples; some at the height of
1000 feet above the sea. It is to what has been described,
no ce that Lanpr alludes in the passage quoted in page
second,

a

It

. A
~ 3 s ’ e é
* * we

» ‘9 ».
222 GEOLOGICAL FACTS OBSERVED | © ?. ‘
¢ + a >,

It has been observed to me, that what has been remarked on™
the upper surfaces of the beds of Faroe, cannot be reco ciled '
with the ideas I had formed respecting the matinee, which ~~
the slagginess of the under surfaces had been produced. Though a
all I wish to contend for, in either case, is, that heat had op
rated, I request the indulgence of the Society, while I shortly ~~
endeavour to show, how a lava, flowing at the bottom of the ~ .

|
sea, might also assume the marks of fusion on the upper sur- ©.

face. , * 7
The effect of water on the surface of metals in a state of
fusion, is well known to be the production of wrinkles. This
is the case also when any viscid substance, whether fluid by fu- ;
sion or otherwise, becomes gradually solid while in motion. ©
In the case of water applied to the surface of a hot body, the ~
phenomena are familiar to most persons. When, for instance, ©. &
brass is in fusion, a few drops of water poured upon it remain
suspended almost without motion; but as the heat dimini- -
shes, the water approaches nearer and nearer to the hot
surface, and at length coming into contact with it, violent
ebullition and quick evaporation take place. In the case
of a lava erupted at the bottom of a great depth of sea, a
stratum of steam must be produced, continuing, while the heat ’
exceeds a certain degree, to keep the water and the hot mass_ -
separate. In the operation of boiling the mercury in a baro-,
meter tube, an event analogous to this takes place, and we see
the column of mercury raised up by the vapour occupying the ~~
lower end. As the heat of a stream of lava flowing under the, °
sea is reduced, and the lava itself becomes viscid, its mo-
tion, combined with the action of the water coming into
contact with it, will infallibly produce a ‘surface full of "
wrinkles; and therefore we should expect to find the upper a
. surfaces 4

“4

> a el
» ® o *

to We 2? 9
% ad IN THE FAROE ISLANDS. 223

* ‘ . 4
ples before the Society. — |
>. In considering this subject, it ought to be observed, that
, steam is not like permanently elastic fluids, which, when they
> escape, overcome any pressure of water, and rise quickly to the
surface. In the case of water above a greatly heated surface,
” . there is a constant production, as well as a constant condensa-
“am at tion of steam; and the water itself may, to a considerable ex-
>. tent, become greatly heated. But steam produced under the
: ¢ lava, by its flowing over a wet, and, if tuffa be present, over a
- spongy surface, would act in a very different manner, as I have
§) shown in my account of the Mineralogy of Iceland. It will
have a tendency upwards, and will act upon the hot mass, ren-
«dering it more or less vesicular, according to its degree of flui-
a a? dity aes ,
. Doe Thus .
. »
s

»
~~ a
a _* 2 4 . ’
i et faces of submarine lavas uneven and rough, as in the ex-
_* “am

* « When the lava is very hot, and consequently very liquid, the steam will
have less difficulty in penetrating it than when it is viscid. We may con-
ceive cases in which the lava burst forth in such a high state of liquidity, as
to permit the whole of the moisture to pass through it in the form of steam ;
in such a state of viscidity, as to admit of its escaping very slowly, so that the
‘lava may become solid, and, by confining the steam, more or less vesicu-
ae lastly, so tough, that the exertions of the elastic vapour shall be -
confined entirely to the lower surface of the lava. In the first case, a com-
: »pact mass of stone would be formed, having no appearance of the action of
of. heat; in the second, on account of the pressure of the superincumbent wa-
‘ter being sufficient to prevent the escape of carbonic acid and other volatile
ca » ingredients, a vesicular and amygdaloidal mass would be produced ; and from
~~ the last would result a mass entirely compact, excepting at the under surface.”
Travels in Iceland, chap. 1x.

_

a

%. _ To this passage of the text the following note is subjoined : -
mS a ** In such a case, it is possible that the steam, when condensed, would, in -
7 - some instances, remain confined in the stone in the form of water; and thus

Bs" . : the

7 - .
oh . €.

: ; 2
BIA GEOLOGICAL FACTS OBSERVED > hs

Thus it appears, that the marks of fusion, exhibited [by they §
upper, as well as the under surfaces of the beds, are “ee
reconcileable to the supposition of their having flowed 4 a
state of fusion at the bottom of the sea. ie

Another point of resemblance between Iceland and F aroe
remains to be noticed. Lawnoprv, in his description of Far
(which, as far as I had the opportunity of judging on’ the ee ae
is a very faithful one, though his translator does not always do
him justice), mentions great fissures which can often be ee 4
from one island to another. We found that these fissures | had.
been originally entirely filled with veins of basalt ; and in those
only did that rock occur to our observation. “pete columnar,
and the columns being perpendicular to the mallee the ba- ~
salt is easily broken down; and water-courses being form- «
ed, the veins are soon worn away. On examining the.
sides of the veins, we found, though not in every instance, —
a vitreous coating, similar to what was observed on those of
Iceland. ~

Thus, the perfect resemblance between the trap rocks of Fa-
roe, and those of Iceland, seems to be completely established.
The beds are separated by the same substance, viz. layers and
beds of tuffa. They present indications of fusion; and Fa-»
roe has afforded some of a new and very decided charac-
ter. I have heard that similar appearances exist in Norway ;
and it is not improbable, if geologists take the trouble of look- ‘a
ing for them, that such will be fonnd in every country whol-
ly composed of trap ;_ i and that the igneous origin of that , %

genus"

the fact of water being found in the vesicles of basalt and other rocks, may

be accounted for. It must be observed that the steam, in such circumstan- "
ces, must have been very much condensed, so much, indeed, as to be almost
in the state of water greatly heated; much more so than in the familiar ex-
periment made with Papin’s digester.”

bed v4 ‘ a ied ® *
» ‘ ‘
« ” .
- -
* ¥ .

“os

- .- «"? IN THE FAROE ISLANDS. 9925

i. 2
* > a

$ © genus ¢ f rock will be established beyond a doubt. The discove-
ae “zy of submarine lavas, the idea of which first struck the cele-
Le br ted Tino, serves as an additional illustration of the
magnitude and various exertion of that power, which, when
subjected to the control first conceived by the ingenious
' Horton, explains almost every phenomenon of the mineral Te-

* © gions. ‘ . ;
While the great point, the action of heat in the formation of
> trap rocks, seems to be demonstrated, forming a theory of the
manner in which heat has operated in particular cases, is, in 2
gocral view, perhaps not absolutely necessary in the present:
*y ‘state of geology. Yet it is satisfactory to the mind when any
‘explanation, consistent with the laws of nature, is suggested.
* The theory of submarine volcanoes is not meant to be extended
%® . to the appearance of beds of trap interspersed between strata of
a sandstone and other rocks. These have been thrust among
, the strata from below, and have probably been the cause of the
strata being elevated above the sea, in which they were form-
ed. The succession of beds of trap, one above another, is the
fact which the theory of submarine volcanoes is intended to
. explain; and though it may not be thought to afford grounds.
for conviction, yet, in. a case where the agent employed is of
. unlimited power, the imagination is led, by this theory, into a
scene on which it can dwell with some degree of satisfaction.
Some affect to view geological theory in the light of idle spe-
© culation; while others, of whom I am one, consider it the
“gmain spring of research, and the direct road to discovery.
There are three descriptions of geological facts of importance
to theory ; those which support it, those which are difficult to
-.» account for, and those which can be explained by the opera-
tion of agents opposite in their nature, as fire and water. In
proportion as the first accumulate, the second present fewer

Vou. VII. Ff obstacles ;

-

296 GEOLOGICAL FACTS OBSERVED :

obstacles ; and the last, which may be called neutral, are asso-
ciated with the first. Difficulties remain to be overcome both .
in the Huttonian, and in the Wernerian system; and unless
the partizans of each were zealous in applying their doctrines
to the facts which they discover, the face of nature would cease
to be referred to for those steps by which alone we can hope
to arrive at a perfect system: and our progress would be so
slow and heavy, that prejudice might take possession of our
minds, so as to shackle, if not to exclude, the free exercise of
reason. |
Rocks such as those of which the Faroe islands are formed, are
very liable to destruction by the operations of the atmosphere.
The great abundance of springs, which is characteristic of a trap
country, aid the action of frost. Accordingly, the whole of Faroe
exhibits extensive marks of the constant and destructive opera- 3
tion of these agents. The sea, too, rapidly undermines the preci-
pices, large masses of which are daily buried in it. As all the
narrow channels which separate the islands, lie in the same di-
rection, and as veins of basalt are sometimes seen as if branch-
ing from them through the adjacent islands, I am induced to
suppose, that the separation of the islands has originated in the
destruction ef large veins, subsequent to the land being eleva-
ted above the sea, and caused in the same manner as that of
‘other veins or dikes, now going on. The support of the walls
being removed, decomposition, and the effects of moisture and
frost, would operate in gradually destroying the beds, and at ~
last the sea, breaking through (as it is constantly doing in va-.
rious parts of the islands), these channels might in this manner
have been formed. In the same way, the position, in some
instances, of those huge masses which now stand separated
from the coast may be accounted for. Indeed, in several pla-
ces, we saw the separation actually proceeding, by the remo-
7 val

IN THE FAROE ISLANDS. 997

val of veins, particularly near the village of Tiornevig in Stro-.
moe.

os

An account of some other geological facts, of the varieties
of the trap, and of the various minerals contained in them, I
leave to my friend Mr Auuan, whose great accuracy in such
descriptions is well known to the Society,

Ef72 No. VIL.

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HNL JO LEI

VII. An Account of the Mineralogy of the Faroe Islands.
By Tuomas Axuan, Esa. F. R. S. En.
; Mf

A

[Read 1st February 1813.]

IR Grorer Mackenzie having already given a paper, en-
S titled, “ An Account of some Geological Facts observed
“ in the Faroe Islands,” it may be necessary to explain why our
communications were not combined in one. This was simply
owing to our objects being in some measure dissimilar. He was
anxious to compare the facts presented in a country decidedly
volcanic, with those in a trap district, where no traces of a vol-
cano were to be discovered ; consequently, his observations were
confined to particular facts: whereas my object is to describe,
without relation to theory, whatever appeared to me interest-
ing in a geological point of view.

I do not propose to embarrass myself with an attempt to re-
duce the various phenomena I remarked, to any existing theo-
ry, farther than what appears warranted by the new and addi-
tional light we derived from some of the appearances in Fa-
roe. I shall content myself with aiding the labours of future

travellers,

230 ACCOUNT OF THE MINERALOGY

travellers, by enabling them to profit by our experience, and
by removing the difficulty we encountered in procuring infor-
mation, regarding the objects calculated to gratify curiosity,
or assist us in our investigations, which neither of the ac-
counts of Faroe published are capable of doing *.

In the following pages, | shall take notice of the objects
most deserving of attention, and particularly note the locali-
ties where minerals are to be found ; and conclude with a few
observations on the geology of the islands.

To this I shall not attempt to add a description of the inha-
bitants, their mode of life, or their means of subsistence, al-
though all are peculiar, and all interesting. It would be teme-
rity to attempt it on an acquaintance of five weeks, although
that time was sufficient to satisfy us, that they are a people in
all respects honest, industrious, and hardworking, who earn
their scanty livelihood with more labour than perhaps any
other set of human beings, while nothing but patience and:
contentment appears to prevail among them.

In our voyage to Faroe, we were extremely fortunate ; al-
though the weather was boisterous, the wind was fair and stea-
dy, so that we cast anchor at Thorshavn exactly in sixty hours
after passing the Isle: of May,—a run of about five hundred:
miles. When we first made the land, the atmosphere was so-
thick, that it was some time before we discovered the island we
were approaching to be the Lesser Dimon, situated between
Suderoe and Sandoe. . The form of this rock is similar to that
of Ailsa; it gave us a glimpse of the trap country we were go-
ing to ransack, and as we approached our anchorage, other
magnificent cliffs successively displayed themselves, affording:
some idea of the grand scenery we were about to-visit.

Having

* The only publications on the Faroe Islands are those of Dewxs and Lannr.
The former appeared in 1670, the latter in 1800.

OF THE FAROE ISLANDS. 931

Having established our head quarters in the house of the
‘Governor, Major Lozsner, who entertained us with the greatest
hospitality, we engaged a servant and a guide, who both of
them occasionally acted as interpreters ; and the weather be-
ing unfavourable for commencing our journey, we delayed a
few days, in hopes of its improvement. We had selected

June, as a season most likely to afford us comfortable wea-
ther; but during the whole month, we had not two days

together that it did not either rain or snow. August and
September, we feund, were considered the most favourable
periods. During this delay, we had time to inform ourselves
of the best mode of travelling through the country.

In Faroe, the term road means little more than direction, as
not even a path is to be discovered in some of the principal
routes, which are merely the most passable cuts across the

_ hills: occasionally a priest may save himself bodily labour, by
“traversing these wastes on horseback; but a stout man will ge-

nerally accomplish the same distance in less time on foot.
Where a country is so entirely intersected by the sea, inland

‘communication is but seldom resorted to, ner would it at all

answer the purpose, where such constant intercourse is requi-
red ; the inhabitants of the most distant parts being obliged to
repair almost weekly to Thorshavn, to draw their little por-
tions of grain from the Government store; where the stock
is always so stinted, never more than a fortnight’s allow-
-ance is delivered at one time. Besides, all the habitations are

_ situated on the coast. Boats, therefore, afford the best mode

of travelling, and the only means of conveying goods. Even
to a stranger, there is no inducement to traverse the interior,
which presents nothing but dreary desolation. All the stri-
king scenery is on the coasts, and there only are minerals to
de procured; for although Lanpr mentions, that the best zeo-

lites,

232 ACCOUNT OF THE MINERALOGY

lites he got, were found among the debris upon the sides of
the hills, those we picked up in such situations, were uniform-
ly deprived of lustre, and otherwise much damaged.

The boats are principally used for fishing; they are all con-
structed in the country, of plank brought from Norway. They
are built in the canoe shape, and though not very commodious,
are so admirably fitted to the seas of Faroe, that I do not.
recollect, during the whole of our excursions, to have been in
the least incommoded by the rising of the spray. The conti-
nual practice of the natives, and their constant habits of attend-
ing to the tide, not only for the purposes of their avocations,
but also to mark time, when the sun is obscured in clouds,
renders them extremely expert in the management of their
craft; yet they never venture their boats to sea without ha-
ving them well manned,—a precaution extremely necessary,
where, by the rapidity of the currents, andthe sudden gusts
of wind, the waves are thrown into the most violent agitation:
almost instantaneously.

The Faroe Islands being so celebrated.as the source of the
finest zeolites and calcedonies, which decorate the cabinets of
Europe, there expected to find a perfect magazine of every thing
magnificent of that nature; and never doubted that we should
meet with people in plenty, who, if they had not objects of this
description to dispose of, would at least be able to conduct us to
the places where they were to be procured. I was therefore sur-
prised, that not one person in Thorshayn could give us any sa-
tisfactory information. on the subject. Such is the indifference-
those beautiful productions of nature, so justly prized abroad,
meet with in their own country. Our guide, Hans, who had also.
attended Sir Joun Sranizy in the same capacity, told us, that.
that gentleman had supplied himself with zeolites from a cave
in Nalsoe, about twenty-three years before ; but that he had

not

OF THE FAROE ISLANDS. _ 233

not been in it since. Knowing what a hopeless measure
it is to explore a country in quest of its mineral produc-
tions, without being previously directed to the particular spots
that afford them, this information occasioned considerable cha-
grin; and as it appeared we had only our own exertions to
depend upon, we commenced operations with all possible
speed.

That part of Stromoe which surrounds Thorshavn is tamer

_than the generality of the country, and, so far as we could dis-

cover, presents nothing of interest to the mineralogist. . We
therefore immediately proceeded to explore Nalsoe, a long
narrow island which lies within five miles; and here we found
a constant source of amusement ™.

Almost the very first. object. that attracted our attention on
landing, was the very remarkable appearances of fusion, on the
surface of a bed of amygdaloid, mentioned by Sir Grorce
Mackenziz. These occurred on a point as nearly due east as
possible from Thorshavn. Two miles south of this is the
cave in which Sir Joun Srantry had found so many brilliant
specimens of zeolite. It is described by Lanopr as a very re-
markable cavern, not, however, for its productions, of which
he takes no notice, but as leading to a perforation said to pass
so nearly through the island, that the noise of the waves on
the opposite side may be heard at the extremity of it. This
aperture I could not, find; it may, however, be covered with
debris, the place being so, much altered since Hans our guide
was there before, that | he scarcely knew it to be the same.

It is situated considerably above the level of the sea, in a
soft amygdaloid, and presents an opening of about two hun-
dred feet in length, while its inmost recess does not exceed

er Vil. | Gg eighty,

* ne the annexed map of the Faroe ‘Tela, reduced from that of Captain
Born, I have traced our different routes.

234 ACCOUNT OF THE MINERALOGY

eighty ; in front it is nearly closed up with debris, which slope
gradually into it, so that it is in many places quite low. Here,
both in the solid rock, and among the fallen fragments, we
found specimens of zeolite in abundance, of the species Stil-
bite, Apophyllite, and Chabasie.

The first of these was the most abundant, and occurred very
beautifully crystallized, in irregular crevices, disposed in
groupes, on globular mesotype, mixed with minute crystals of
chabasie, and of the following forms:

l. Flat rectangular prism ; the broad surfaces of which have
a lamellated and pearly aspect, while the narrow ones
are longitudinally streaked, with smooth shining termi-
nations, set at right angles to the rest, forming a paral-
lelopiped. 7

2. The same; having each of the solid angles replaced by
two planes, set obliquely on the narrow sides of the
prism, presenting the form dodecaddre, fig. 118. of
Havy.

3. When the replacement of the solid angles is not complete,
part of the terminal plane of the first variety remains.
Form epointé, fig. 179. of Havy.

Besides these, we found it in radiated and lamellar masses,
and in aggregations assuming the sheaf shape.

The Apophyllite is a rarer mineral ; we found it only among
some of the fallen masses of rock, disposed on a ground si-
milar to, the last, and, mixed with. crystals of stilbite. The
forms it assumes are very simple, and as follows:

1: Equilateral rectangular prisms ; terminated at each end
by a plane set at right angles. Here the sides of the
| boonbo: | | prism

i}

OF THE FAROE ISLANDS. 235

prism are all streaked, and the terminations pearly ;
these crystals appear to have but one cleavage, which
is at right angles to the axis, and extremely distinct.

2. The same; slightly truncated on all the solid angles.

3. The same; with the truncation on the angles somewhat
deeper; a small four-sided facet remaining on the sum-
mit, forming a truncated pyramid.

In other specimens I have found the apex complete,
producing a very distinct sharp-pointed pyramid *.

We here likewise found radiated’and amorphous mesotype ;
also in most delicate minute acicular fibres.

Chabasie occurred here only in very small crystals; but
towards the southern extremity of Nalsoe,,we found it in
very large crystals, some of them at least an inch in diame-
ter ; they were imbedded in a very tough rock, and, being
naturally brittle, we were unable to detach them.

From the southern point of Nalsoe, a portion of the rock
was removed some years ago to Kongsberg in Norway, for the
purpose of extracting the native copper dispersed thréugh it ;
this, however was not found to answer, from the small quanti-
ty it produced. Another spot was also pointed out to us as
affording copper, on the east side of the island, a little north of
a small detached rock called Kabelen, and not very distant from
where we first saw it.

Gg2 I

* This variety has been referred by Havy to the species Mesotype. From
the great respect I entertain for the opinions of that distinguished mineralogist, it
is with reluctance I venture to place it under a different name. It is not, how-
ever, without due consideration that I have done.so: my reasons I shall detail
more fully, when speaking of the Crystallised Mesotype.

236 ACCOUNT OF THE MINERALOGY

I here had the good fortune to procure some very good spe-
cimens of the metal, in rather larger bulk than usual, very
beautifully crystallized, with some of the sprays forming the
nuclei of radiated mesotype; which, when considered in a geo-
logical point of view, is a circumstance highly deserving atten-
tion. Here the native copper is found in amygdaloid, at no
great distance from the spot where we saw a bed of the same
material covered with the most decided marks of fusion. It
does not traverse it in veins, but is disseminated in minute par-
ticles, and sometimes presents crystallizations, equal in beauty
to any from the veins of Cornwall, although imbedded in the
solid substance of the rock, through which it branches with the
utmost elegance and freedom.

The places I have mentioned as the localities of these
minerals, with one or two others, rather of less note, were
the only spots we landed at. There were many others, which
appeared sufficiently inviting; but from the roughness of the
waves, and the quantity of sunken rocks, we could not with
safety approach them.

Having delayed some time, vainly waiting for good weather,
we. at. ine proceeded to the western coast of Stromoe, and
took up our lodgings at Quivig, in the house of the priest, Mr
Horm. During our voyage to this place, the. mist lay. so
thick upon the islands, that we seldom could see the summit
of the cliffs, near which we were obliged to steer; in order to
‘keep our course.

Our host at Quivig, was the only person whom we met with
in Faroe, in the habit of collecting its mineral productions ;

and although he did not appear to have, made, avery good
‘selection for himself, yet he. conducted. us to. different: .ca-
vities,.on,the shore, from: which we' ‘obtained some of the finest
zeolites that ever were e brought from these islands. Some of the
cavities

OF THE FAROE ISLANDS. 237

cavities were three feet in diameter, and entirely lined with large
crystals of stilbite; but .the most interesting, were between
Quivig and Westmanhavn. In one, we observed the mesotype,
in long acicular crystals, but so extremely slender, that it
was quite impossible to detach them entire from the rock.
In another, we found the same substance, but in a more tangible
form. This cavity was about two feet wide, eighteen inches
deep, and nine high, in a perpendicular rock, about ten feet
from the base, which was washed by the tide. By means of
a ladder, we succeeded in reaching this repository, and found
the whole interior coated with aggregated groups of stilbite,
having only the crystallised acuminations visible, of an opake
yellowish-white colour, and varying from an inch to an inch
and. a half in thickness. Upon this ground were disposed nu-
merous groups of mesotype, radiating from a centre, and shoot-
ing from the surface, an inch to an inch and a half in length,
in clear, transparent, well-defined prisms, of a rectangular
form, terminated with a flat four-sided pyramid, the variety
pyramidée of Hauy, and varying in size from a hair to a line
in thickness. | It was a mortifying circumstance to be obliged.
to destroy any part of this very magnificent specimen, in de-
taching it from the rock; a circumstance, however, totally un-
avoidable. I succeeded in obtaining several very good speci- ©
mens, and. by gluing them carefully to the bottom of a box, was.

very fortunate in preserving them in all their natural beauty.
This is the Mesotype of Havy, and the Nadelstein of Wer-
NER ; it varies entirely from the Apophyllite formerly noticed ;
in place of a distinct foliated cleavage, cutting the axis at
right angles, with a pearly lustre on its terminations; it pre-
sents a vitreous fracture, without the appearance of any regu-
lar cleavage, and an uniform lustre in all directions. Fragments
of Mesotype dissolve in nitric acid, and form a clear transpa-
rent

238 ACCOUNT OF THE MINERALOGY

rent jelly ; while the Apophyllite separates into minute parti-
cles, of a semitransparent white *. It .besides varies in refrac-
tion, and is in all respects similar to the Mesotype from Puy
de Dome, a magnificent specimen of which I had lately the
honour to receive from the hands of Monsieur Havy.

On the east side of the Bay of Westmanhavn, we found
other cavities containing Mesotype. We there also discover-
ed a vein of calcareous spar, about two feet in width, from
which we detached several specimens ; it was entirely compo-
sed of a congeries of crystals, among which were imbedded,
rounded masses of amygdaloid. The forms here presented by
the carbonate of lime are quite new to the mineralogist, and are
particularly described in the late work of the Count de Bour-
non, who has added to his already numerous collection of the
crystallizations of that substance, no less than eleven varieties.
To his interesting work I beg leave to refer for their enere.a
description 7.

Having been compelled to abandon our intention of ascen-
ding Skcelingfeld, from the state of the weather, we were like-
wise advised not to attempt the open sea, by which we propo-
sed to proceed on our journey to Osteroe. We therefore
passed over to Wagoe, and paid a visit to the island of Tint-
holm.

The peculiarities of Tintholm are not ener in the
translation of Lanpr, although fully described in the origi-

nal.

* The Apophyllite of Uté in Sweden, as well as of Disco in Greenland, after
separating in the acid, swell out in a very remarkable manner, occupying a
space very much larger than the original; but do not combine into a gelatinous _
mass.

+ Catalogue de la Collection Mineralogique du Comte de Bournon, London,
1613.

OF THE FAROE ISLANDS. 239

nal. This little island forms a continuation with the west
side of the Bay of Sorvaag, but is not seen from the village of
that name. We there obtained a boat, to proceed towards. it,
and in going down the bay, which is very narrow, we came
suddenly in view of it, with all the singular and grotesque
rocks by which it is surrounded. One of these is perforated
by the sea, forming a very fine natural arch; while another,
like an enormous column, placed crooked on its base, stands
as if prepared to fall into the abyss beneath.

The summit of Tintholm may be from five to six hundred
feet above the level of the sea; it is divided into a number of
pinnacles, so extremely slender to appearance, that it becomes
a matter of surprise how they resist the fury of the storm. This
peak presents on the south side a bare perpendicular cliff, and
appears to be principally composed of amygdaloid. The only
observation we made here, was with regard to the extreme si-
milarity of the trap-tuff to that which Sir Grorce Mackenzie
met with at Akkerfeld, and in other parts of Iceland. It con-
tained no minerals of any notes

Here, for once, the weather favoured us; and although the
cliffs of Wagoe were not more elevated than others we had
previously seen, they were disincumbered of clouds, and
when viewed from the farther extremity of Tintholm, form-
ed a most sublime prospeet. At the time, we could’ not

sufficiently estimate their altitude; but the diversity of
form into which their summits were broken, and the fine
contrast afforded by the intervening rocks, with the beautiful
effects of light, altogether rendered our visit to this place ex-
tremely gratifying, particularly, as we were not at all prepared
‘tomeet with any thing of the kind; and we left it. with a feel-
‘ing, that overlooking Tintholm, would have been the omis-
sion of an important object of curiosity, in a tour to Faroe.’
Next

240 ACCOUNT OF THE MINERALOGY

Next morning Wagoe was obscured in heavy clouds of thick
mist. When the tide served, we left Midvaag, on our return
to Thorshavn; but had no sooner fairly quitted the shores of
this island, when, emerging as it were from darkness, we had
a view of Skeeling, and the other mountains of Stromoe, with
the islands of Hestoe, Kolter, Sandoe and Suderoe, none of
which had been visible as we passed them before.

It very frequently happens, that one island is enveloped i in
fog, while the next is quite clear of it. The clouds take their
partial stations with inconceivable tenacity ; and, according to
the direction of the wind, it was usually known what sort
of atmosphere was enjoyed in the remote quarters of the
group. °

From Thorshavn we proceeded on a second tour, to Eide, a
small village situated at the farther extremity of Osteroe. The
channel which divides the two principal islands is very narrow
in some places, and cannot be passed at all times of tide, even
in the small craft of the country, being traversed by a reef of
rocks near the middle. The hills are generally tame on both
sides of this passage, excepting at Zellatrae, where there is a
magnificent bed of columnar greenstone.

At Eide we remained some time ; but our proceedings were
still sadly impeded by the weather; we, however, had an op-
portunity of ascending Slattertint, a neighbouring mountain,
apparently not much lower than Skeeling.

According to Captain Bory, the last-mentioned is only 2400
feet high. F rom the very excellent chart constructed by that _
gentleman, after an accurate survey of the islands, in which
even the shading of the mountains is executed with great cor-
rectness, we ought to state with diffidence, that our measure-
ment of Slattertint, by means of a barometer, indicated an

elevation of 2825 feet; from its summit we could discern,
. that

‘OF THE FAROE ISLANDS. 211

that Skeelingfeld was considerably higher, and, according to
our estimation, not less than 3000 feet above the level of the
sea. We had no opportunity of repeating our observation ;
but as we took all possible pains to guard against error, we
have room to suspect that Captain Born must have fallen into
some mistake ; although, from the opportunities of observing,
which his long residence in the country must have afforded
him, we cannot, without much hesitation, come to such a con-
clusion.

* In this excursion we had reason to congratulate ourselves on
our good fortune. The atmosphere was clear of clouds, conse-
quently almost every island in the group was within sight,
which, from the wonderful variety in the form of the hills and
islands, affords a very grand and striking prospect.

The peculiar delight one feels in the enjoyment of a

boundless view from an elevated situation, was, on this occa-
sion, considerably enhanced by the unobscured horizon, and
peculiar brightness of the day; since our arrival in the coun-
try, we had not till now enjoyed a single hour, that would
have permitted us to see half the extent. Though bleak
and barren, and in many places covered with eternal snow,
the novelty of shape, which varied in every hill,—the deep
‘indentations of the sea,—the contrast of the irregular out-
Ime with the even and unvarying direction of the rocky beds,
and the placid stillness of the surrounding ocean, all contribu-
ted to repay us most amply for the trouble of our ascent.
“y Like many of the Faroe hills, the summit of Slattertint is
flat, and presents an irregularly oval plane, of sixty yards by
thirty-six in its greatest dimensions. This surface is covered
with thick moss, under which the soil was completely frozen.
We observed nothing remarkable in the composition of the
beds, and no minerals of any consequence.

Vor. VII. Hh The

949 ACCOUNT OF THE MINERALOGY

The village of Eide is situated on the-acclivity of one of
the headlands which presents a perpendicular front to the
ocean. Some of these we had previously been much strugk
with ; that of Nypennes puzzled us extremely. Lanpr re-
presents it to be 1200 feet high, which, from the magnitude of
every thing around, the little distance we thought we were from
it, and without any object by which we could form an estima-
tion, we could not bring ourselves to believe. I was therefore
determined to ascertain, by the simple mechanical means of a
line and plummet, the height of the Kodlen, as. the headlané
near Eide is called, and succeeded, by letting down a fishing-
line, with a stone at theend of it, from the top of this fermi-
dable precipice, from which I ascertained its height to be
1134 feet *. 'Fhis, I believe, is a very near approximation to.
the truth: the elasticity of the cord was the only material source
of error; but I.-endeavoured to counteract this defect, by.
stretching the cord sufficiently when it was measured off.

We were thus furnished with the means of forming a.
proper estimation of these tremendous cliffs, and without it.
we should in all probability have left the islands under a very
different impression regarding them than we did. The Kod-

| GS “AE Beater WS len

* It was not till after the third attempt. that I was satisfied with this experi~
ment. In the two first I met with unlooked for difficulty, by the hitching and
entanglement.of my cord, upon the projecting points. of the rock, and also by, the
severity of the blast, which, striking on so large a surface, blew upwards with
tremendous fury, even when- there was otherwise apparently but little wind. I
consequently bethought myself of coiling a given quantity of cord, upon a round
stone, and forming a compact mass, of sufficient weight to overcome the violence
of the wind opposed to it at the summit, which decreased proportionably to the
opposition it met with in descending; while the shape, and unfolding of the
rope, rendered it less liable to attach itself to-the points of the rock. By means.
ef this device, I succeeded to my satisfaction.

OF THE FAROE ISLANDS. 248

len is by no means remarkable for its elevation; the Myling,
in Stromoe, is at least a third higher. presenting an unbroken
mural front, with scarcely a point for a bird to perch upon
from the summit to the base.

On the west sidé of the promontory, opposite Thiornivig,
and also on the east side, upon the shore, we observed nume-
rous indications of fusion upon different surfaces of the rocks ;
and it was from this vicinity that we procured the principal
part of the specimens, bearing ‘testimony of this fact, that we
brought home with us. It was among some large fragments,
also on the east side, that we discovered specimens of apo-
phyllite altigekh ert rare for the magnitude and beauty of cry-
stallization.

They here occur in ti a iotka. eieengn perfect cubes,
sometimes longer, sometimes shorter ; occasionally, the cubes
are truncated upon the solid angles, either slightly, or so
deeply as to meet, forming the regular cubo-octohedron.
The crystals, like those formerly mentioned, which we found
in Nalsoe, are streaked on the sides longitudinally, and have
a pearly aspect on the terminations; they are disposed on a
ground of mamillated mesotype, and in some _ instances
grouped like fluor-spar ; the cubes being irregularly implanted
-on each other. They are perfectly transparent and colourless,
except when affected by the weather, which renders them dull
and opake. The largest I met with measures seven-tenths of
an inch, by five-tenths. I was assured by M. Varina, a Spa-
nish mineralogist, and a distinguished pupil of Werner, that
it is to this variety he gives the name of Cubizite, although it
is under that appellation the Analcime and Chabasie of Havy
are described by Brocuant and others. It may be, therefore,
that the Cubizite of Werner, is in fact the Apophyllite of
. Hh 2 3 Havy,

244 ACCOUNT OF THE MINERALOGY

Havy, and that Wrrner’s Nadelstein should be confined to
Havy’s Mesotype.

The only other circumstance of interest which I met with
near Eide, was a remarkable instance of the abrasion of the
surface, where the rock appears to have been worn down by
the friction of heavy bodies. Of this I shall take notice in the
sequel.

Again, we were obliged to abandon our station, without
completing our intentions, in consequence of the badness. of
the weather; and being deterred from venturing to the north-
ern islands in this direction, we returned to Thorshavn,
resolving to attempt it by the south side; and after some
delay for a favourable day, we reached Waaij in Bordoe,
with tolerable prospects of success. Here we had just landed,
and prepared ourselves for our afternoon’s excursion among
the neighbouring hills, when it began to rain heavily, and conti-
nued pouring for fifty hours, accompanied with sleet; on
the third evening a shower of snow commenced, and next
morning the mountains were clothed in white almost to the
water’s edge. It was now the 23d day of June, and yet this
inclemency created no surprise among the natives, who assured
us, that at Christmas the weather was generally better. The re-
cent snow did not lie long, and, anxious to do something be-
fore we left the place, we ascended a hill which: lies on the
west side of the village, while it yet snowed, and were repaid
for our trouble, by observing marks of fusion, similar to those
of Eide, but at a height of at least 1200 feet, We had hither-
to found them only close upon the shore.

Despairing of being able to proceed farther, and as our pro-
visions were not calculated for so longa delay, we were compel-
led to return to ’Thorshavn, and busied ourselves in directing
preparations for our final departure. At this time the weather
suddenly

OF THE FAROE ISLANDS. _ 245

suddenly assumed a more settled appearance than it had hitherto
done; and having still a few days at our disposal, we resolved
to make a last effort, to visit the objects we had hitherto been
prevented from seeing. We had now to retrace a great part
of our former track ; but the difference of weather rendered it
entirely new to us. Formerly, as one cloud followed another,
we caught an occasional glimpse of the coasts along which we
were steering; now we had a delightful view of all the islands
and groups of mountains, perfectly unimpeded; and their
rough surfaces afforded as magnificent effects of light as can
well be imagined. One of the most extraordinary of these, is
in the island of Wagoe. On the north side of the entrance to
the Bay of Midvaag, there is a fragment of a rock standing out
from the rest, to which, from its acute pyramidal form, they
have given the name of the Trolkende Fingeren, or Witch’s
Finger. As we approached it from the extremity of Stro-
moe, the light struck upon it, and the rocks in its vicinity,
exactly so as to produce the appearance of a Gothic cathedral ;
an appearance not requiring fancy to help it out, but actually
demanding attention to overcome the illusion. We had pas~
sed close under this rock twice before, but had not till now
seen it.

We again passed our former residence at Quivig, and reach-
ed Westmanhavn soon after noon. Next morning we were
ready to start on our long meditated expedition at an early
hour. The weather was fine, and the water in the bay as
smooth as any lake; still the people wished to dissuade us
from venturing upon the open sea, asserting that we should find
it very rough without. We now began to be less moved by their
representations than formerly, having observed their extreme
caution, or rather timidity, on all occasions. We determined
to proceed, and although the sea was certainly more agitated

than

246 ACCOUNT OF THE MINERALOGY

than we expected, all inconvenience it occasioned soon ab-
sorbed in the stupendous grandeur of the scenery that open-
ed upon us. From the northern coast of Wagoe, all the way
to Eide, we had a continued series of magnificent cliffs, tower-
ing in many places, like minerets, to the height of 2000 feet.
Here also we saw a series of rocks, which, from the accounts con-
tained in Lanpr, had excited a great degree of curiosity: al-
though they do not by any means accord with his description,
yet they present some of the wildest and most magnificent ap-
pearances possible. Here a part of the coast is separated from
the rest, and appears to have formed a barrier or wall in front,

the ruins of which now only remain. In one place, where the
largest portion stands highly elevated from the water, an im-
mense perforation, like a grand portal, presents itself, through
which boats of any size may row in safety. The rest of this
reef, as it may very properly be considered, presents a string
of fantastically shaped rocks, many of them acute pyramids,
denominated Drengs in the language of the country, in a line
at unequal distances. In a little narrow bay near this, of about
three or four hundred yards in depth, there is another wall,
somewhat similar, dividing the bay in two; the extremity of
which ranges with the entrance of it. The end towards the
sea is highest; and from this it declines to the other,
being ornamented all along with the same kind of pinnacles
we formerly admired at Tintholm. In it we also found a na-
‘tural arch, through which we passed in the boat. These walls,

I first suspected, might have been the remains of enormous
dykes, similar to some which exist on the coast of Antrim ; but
on examination, I found no traces to support that conjecture,
nor could I discover any probable cause for their mitaepct
from the adjoining country.

-We

OF THE FAROE ISLANDS: JA'T

' We arrived at Eide in the afternoon ; and from thence pro-
ceeded, early next morning, towards the northern islands,
directing our course to Wideroe. From the general appear-
ance of the country, and the perfect sameness we every where
met with, in its geological characters, we found there was little
inducement to prolong our stay in this quarter, and therefore -
resolved, if circumstances permitted, to return the same day to
Thorshaven.

The morning was beautiful ; and as we skirted bap we had '
a delightful view of the coast, which presented many of the
singularly shaped rocks, of which we had seen so many the
day before. Being obliged to keep out to sea, to get into the
current, we had an opportunity of comparing the relative
heights of the Myling and Kodlen, and to form avery accurate -
judgment of the former, by knowing the altitude of the latter. .
We now passed along the islands of Kalsoe and Kunoe, which
are little more than lengthened ridges of barren rocks, pre-
senting the most frightful aspect of sterility. We arrived at.
Witlatoe a little Before mid-day ; it is situated on a peninsula,
the isthmus of which is of considerable extent: on the left, the
rocks rise, in wild. and rugged peaks, to a very great height ;
and having viewed the bold and rocky shores of Fugloe ie
Swinoe, fori the opposite side of the ee we again em--

barked. ‘

It was our intention, at this- place, to have einai our’
boats ; but the people being all engaged abroad, plucking their.
sheep *, our crew from Eide offered to take us forward, appa-
rently delighted with the opportunity it gave them of obliging
us. We had already come twenty-three miles, and were dis-

tant:

* The savage custom of: tearing the wool from the backs of their sheep, still
prevails in these islands.

248 ACCOUNT OF THE MINERALOGY

tant thirty-three from Thorshavn, where our people were still
twenty-three miles from Eide; and as they never remain:
from home over night, they had to complete a journey of se.
venty-nine miles without rest, and almost in the constant ex-
ercise of the oar. From their knowledge of the tides, they
are enabled to take every advantage of the current; but ina
voyage of this extent, it was impossible to have it always
favourable ; we were therefore more than once stationary for
upwards of half an hour; the utmost exertion of the crew be-
ing barely sufficient to prevent the boat being carried back
with the stream, in turning some of the headlands we had to
pass.. About eight in the evening we reached Thorshavn,
where, after resting an hour, our crew left us to return home,
and arrived there at two in the morning, having performed
their voyage in nineteen hours, including stoppages, an
exertion which may appear incredible but to those who saw
it. }

By this rapid and successful voyage, we retraced in three days
nearly all our former excursions, and, besides, accomplished our
visit to the northern islands. We were now fully satisfied, we
had nothing new to expect by extending the period of our stay,
and nothing now remained worth examination, except the island
of Suderoe, which, lying in the course of our return, we expec-
ted to stop at after our final departure from Thorshayn; but
in this we were unfortunately disappointed.

We were likewise satisfied with the supply of minerals we
had obtained. We had made a splendid collection of zeolites,
of every variety, except analcime, of which I was rather sur-
prised not to have seen a single specimen in the country, ex-
cept one solitary crystal, which was found among the debris at
Waaij. Since our return, however, I have procured a very
magnificent specimen of this substance from. Kollefiord in

Stromoe;

OF THE FAROE ISLANDS. 249

Stromoe, not above ten or twelve miles distant from Thors-
havn; a discovery somewhat mortifying, considering we could
have visited it with great facility.

Of Calcedony we had likewise procured several very capital
specimens, all brought by the people to barter against tobacco ;
nor could we learn where they were to be found in situ, being
constantly told, that they were got loose upon the sum-
mits of the mountains, and by the priest at Quivig, that
the place he found them in, was at that time covered with
. snow. Two days before our departure, an accidental circum-
stance led to the accomplishment of what I so much desired:
a country man offered us some masses, having the appearance
of being recently detached, from some small barnacles which
adhered to them being still alive. This led us to inquire where
they were got ; and being informed at Lambevig, within twelve
or fifteen miles distant, we determined to explore it. The
nearest approach to this place is by Skaalefiord, on the west
side of Osteroe. Here we landed at Glibre, and walked over
to Lambe, not three quarters of a mile distant, and having
there procured a boat, were set on shore among the rocks, a
little to the right of the harbour, where we soon found some
immense masses of calcedony.

Our apparatus was now considerably impaired ; besides, the
rock was so situated, that nothing but mining tools could ef-
fectually act upon it. These we had now neither time nor op-
portunity to apply, although we would certainly have done so,
had we come here earlier; as it was, we procured some excel-
lent and interestg pieces of calcedony, as well as some capi-
tal specimens of chabasie. But the circumstance which afford-
ed me most satisfaction on this expedition, was to find the ca-
vernous calcedony in situ. I here saw plates of it of extraordi-
nary dimensions, one being four feet long by two in breadth,

Vor. VII. I which

950 ACCOUNT OF THE MINERALOGY:

which appeared to be parallel, with several others. which I saw
in the same place, and all of them horizontal.

On the shore of Skaalefiord, we also found several mas-
ses of calcedony, of the same description, likewise cavernous ;
and I have no doubt, that by a little attention, abundance may:
be found in the same vicinity.

This excursion was particularly gratifying to me, as it afford.
ed an opportunity of observing some peculiarities in the rela-
tions of a fossil, very much referred to by the supporters of
the two great geological questions, each as affording decisive:
proofs in their own favour. Viewing it as belonging to that
subject, I shall connect my observations on calcedony, with
those I have to make on the geolog gy of the country. ;

The difficulty we met with, in discovering the localities of
minerals, fully confirmed the fears I anticipated on our
first arrival. Excepting Mr Hotm the clergyman of Qui-.
vig, we did not find a person in the country, in the prac-.
tice of collecting minerals. But notwithstanding the appa-.
rent indifference, with which. these beautiful productions are.
treated by the natives, yet they scon found: out’ the ob-.
jects we- were in pursuit of, and frequently afforded consi-
derable assistance in finding them ;, as all , however, depends on =
the care with which minerals are taken from the soil, and as these-
poor people are-destitute of implements for this purpose, it is
impossible they can obtain them in their most interesting
state, even if they were inclined to bestow their time and la-
bour in collecting them, which the difficulty they experience in-
obtaining the more necessary articles of acl aie sisphiea most.
peremptorily forbids. AAAS pa tad

This excursion to Lambe was the- ne The aa flows:
we embarked, expecting the vessel would come’ to anchor off
Suderoe, as was originally intended. But as. we approached.

‘that:

OF THE FAROE ISLANDS. 951

that island, the wind blew so fair, and at the same time so
strong, that we thought it more advisable to bear away, and
had the singular good luck to reach Leith Roads in less
time than we took going out, having performed our expedition
exactly in six weeks.

GEOLOGY.

In the preceding part of this paper, I have purposely tefrain-
ed from touching on geology, in order that I might bring to-

gether the few remarks that occurred on that subject. No

country perhaps presents such perfect sameness in its geologi-
cal relations; from end to end the islands are composed of
trap rocks; consequently, it is only to the peculiarities this
interesting series here affords, that my observations can ex-
tend.

_ Sir Grorcz Mackenzie has already described part of the cu-
rious phenomena I now allude to, which he thinks corroborate

the doctrines suggested by some of the facts he met with in

Iceland, and has, in a great measure, exhausted a subject so
singularly meagre. A few observations, however, still remain
to be made, without entering into any theoretical discussions,

which, though amusing, in the present state of knowledge, are

not capable of leading us to any satisfactory conclusions, with
respect to the general formation of the globe. All I hope to

“accomplish is, to give a faithful description of what I have
- seen; and to mark the impression made upon my mind, by

Ti 2 certain

952 ACCOUNT OF THE MINERALOGY

certain features which distinguish the Faroe Islands from afl
oe countries I am acquainted with.

The Faroe islands occupy a geographical extent of about
sixty miles by forty; their greatest stretch being north and
south. Throughout the whole, there is not one atom of stra-
tified rock to be met with, if I may be allowed to judge from:
the islands we visited, together with what we learned of those-
we did not touch at. I do not consider, that even the coal of
Suderoe presents an exception to this general conclusion.
We have much reason to. regret, that circumstances prevented.
us from exploring this island; as, from some remarks, both
of Deses and Lanpt, as well as from some observations of
Captain Born, which occur in a periodical publication of Co-
penhagen, devoted to natural history, Suderoe contains pecu-

liarities in the arrangement of some of the trap rocks, with
which we found nothing analogous in any of the other

islands. According to Lanpr, the coal-was. particularly exami-
ned by a Mr Henexe,in 1777, in obedience. to. the orders of
the directory of mines; and by his report, the veins extend-in
length: 12,000 feet, and, at an average, 4000 in.:breadth. He
then goes on to calculate the quantity of fuel that an area of
such dimensions would produce. From this it must be suppo-
sed, that, he has estimated in the above sum, the whole of the
coal to be met with in, Suderoe ; consequently, as there are se-
veral places at which it is found, none-of the seams: can be of
large extent. With respect to, the quality of the coal, he as-
serts, that it was found to. be superior to that of Airshire ; but
this cannot be the case, if it be all like the specimens we pro-
cured, which are entirely similar to that occurring imbedded in.
the basalt, in the vicinity of Ballintoy, on the coast of Antrim.
It presents the same ligneous texture ; it burns with difficulty 5
iM

OF THE FAROE ISLANDS. 258

it emits the same intolerable smell; and produces a very large
proportion of ash. At Ballintoy it occurs only in small beds,
sometimes in very minute patches, and is used only in burning
lime. |

I think it is fair, therefore, to conclude, that this coal pre-
sents none of the characters of regular stratification ; and it be-
sides, appears to be totally unaccompanied with sandstone, as
I find it immediately connected with trap in some of the spe-
cimens I have got. So far as we saw, sandstone does not oc-
cur in the country. Lanpr mentions generally, that it is to
be found in the:dales of Nordstromoe. We nowhere, however,
saw any vestiges of it; and from the very low ebb of his geo-
logical acquirements, nothing on that subject, unless corrobo-
rated by other testimony, can be attended to, as we may judge
by the following passages, quoted from Captain Born, as au-
thority. “ If (says he) a bluish-grey fine-grained sort of stone,
“ which contains grains of quartz and calcedony, be not gra-
“ nite or limestone, neither the one or other is to be found in
‘“* the islands.” Page 140.

The varieties of trap we met with, were Greenstone, Por:
phyritic Greenstone, Amygdaloid, Trap-tuff, and Porphyry-
slate. Basalt we found only in a few dykes; we nowhere saw
it in beds, or presenting the beautiful articulated columns of
Staffa and the Giant’s Causeway. ‘The beds composed of
these different kinds of trap, have one uniform dip and direc-
tion; stretching from S. S. E. to N. N. W., and so very slight-
ly inclined, that it. required a considerable portion of the rock
to, be seen at once, to render the inclination. perceptible.
When surveyed from the north or south, the beds conse-
_ quently appear horizontal; while on the east and west sides

an inclination is observed, dipping almost imperceptibly to,
wards the south. . |

This:

J 54 ACCOUNT OF THE MINERALOGY

This arrangement of the mass of beds, prevails with great
uniformity throughout; we observed them to deviate only in one
instance from it, at the western extremity of Myggenaes, where
they rise abruptly to an angle exceeding 45°. There was no
particular uniformity that we perceived, in the succession of
the different kinds of trap, although such might perhaps be dis-
covered on more minute investigation. The trap-tuff was more
abundant than any of the other varieties, and was often the
only material we could distinguish, in cliffs of tremendous
elevation, in which we sometimes found it difficult to trace
the separation of the different beds. When greenstone or
amygdaloid are interposed, the separations are better defined,
and are often divided, by a layer of brick-coloured fine-
grained tuff, which passes into the substance of the adjoining
bed, and is analogous to the red material which forms so stri-
king a feature in the basaltic promontories of the Giant’s
Causeway. The grandest display of greenstone which we met
with was at Zellatrae in Osteroe, where the bed, like that
of Fairhead, is three hundred feet thick, and split in a similar
manner, into prismatic concretions, which, at a distance, give
it a regular columnar appearance. On the top of the hill, at
Leynum, I found the greenstone in the rude columnar form,
which it assumes on the south-west side of Arthur’s Seat;
and in Nalsoe, as well as in some other of the islands, we no-
ticed beds of a description quite new to me. Being considera-
bly elevated in the cliff, we could not ascertain the dimensions
with accuracy. 1 think, however, that, in Nalsoe, may be
from forty to “fifty feet thick; it is composed of vertical co-
jumns, enormously thick. In some the diameters were little
short of their length ; and although they stand straight upon
the base, they are all bent at the sides, so as to present an ir-
regularly waved line between each. The most singular cir-
abs cumstance

OF THE FAROE ISLANDS. 955°

eumstance respecting them is, that they are all coated with an:
arrangement of small prisms, set at right angles to their axis ;.
so that when some of these rude masses are broken in their
longitudinal direction, a circumstance which occurred not -un--
frequently, a double set of small prisms appeared, to separate
the columns, not unlike little dykes; and when an horizontal
direction chanced to be displayed, a radiating arrangement of
prisms was observed around the edge. The substance which
generally occurs, of a brick-red colour, and forms partial sepa-
rations between some of the varieties of trap, seldom extends.
to any great length ; in thickness it is very irregular ; the great-.
est depth we met of it, was in the vicinity of Kirkeboe in Stro-
moe, where it may be from eight to ten feet. It is not
invariably of a red colour: under the greenstone at Leynum, it.
occurs of a dark-green. This material, which in some cases
may very readily be mistaken for sandstone, particularly as it
frequently presents a slaty texture, after being acted on by the
weather, appears to me to form a portion of the overlying trap,.
although it no doubt presents a very different character. In
other beds of greenstone, nearer home, alterations equally re-
markable may be pointed out; and as we frequently observed
in it cavities lined with zeolite, similar to those which were
dispersed through the other parts of the same bed, it cannot
possibly be considered of a separate formation.
Notwithstanding the uniformity that prevails in the general
disposition of the trap in Faroe, there are some beds which dée-
part entirely from it. The most remarkable of these, we met.
with in the vicinity of Norderdahl in Stromoe. “A. little north
of this’ place, there is a conical hill, presenting a projecting
rounded front towards the shore; and being denuded from top
to bottom, the structure is distinetly seen, and the horizontal
beds traccd with the utmost precision. Resting on these, and
covering

956 ACCOUNT OF THE MINERALOGY

covering the summits and sides of this cone, excepting on the
south, a bed of greenstone stretches, which is rendered parti-
cularly conspicuous by the vertical rents of its prismatic con-
cretions. On the west side, after descending more than half-
way from the top of the cone mentioned, it continues towards,
and again rises to the top of Dalsnypen ; from whence passing
under other beds, it may be traced in an undulated line, al-
most without interruption, to Skellingfeld, where it terminates
in a wedge, about half-way from the base of that hill. A little
north of this, and nearly in a line, the same kind of greenstone
recommences, and extends to beyond Leynum. Skeeling pre-
sents on the west side a bare section, like the conical hill of
Norderdahl, whence the beds may be counted in one continu-
ous slope, from the base to the summit, rising to a height of
about three thousand feet; and here, although the powerful
mass of greenstone I have just noticed, loses itself in a wedge,
there is not the slightest derangement created among the other
beds of trap of which Skeelingfeld is composed.

The position of this enormous mass of greenstone is worthy
of attention, and is difficult to reconcile with any of the doc-
trines I know of. Its occurrence in Skeeling, &c. as an adven-
titious bed, like that of Salisbury Craig, is nothing uncom-
mon; but when it extends from under the incumbent trap,
stretching itself over a most irregular surface, and finally co-
vering, as ike a cap, a very acutely conical hill, it assumes a
new and totally different character.

It is in the beds of amygdaloid that the beautiful zeelites
and calcedonies are found. I have already noted the different
places where they occur, and have also given sufficient details
respecting the varieties of zeolite. But as the peculiarities of
Calcedony have often been urged in support of doctrines very

opposite

OF THE FAROE ISLANDS. - 25%

opposite in geology, a description of them belongs more pro-
perly to this part of my subject.

From the proofs we met with in Faroe, of the igneous ori-
gin of trap rocks, I think it almost unnecessary to enter into
any discussion respecting the formation of Calcedony, as no
doubt can very reasonably be entertained of its co-existing with
the matrix in which it is inclosed. The laws by which it
has been regulated, in assuming the various appearances it now
presents, are, however, beyond our reach; nothing I met with~-
tended in any degree to elucidate the cated

Calcedony occurs in the rock in the most irregular masses,
generally rounded, and sometimes shooting into forms like
bunches of grapes. It is either solid, or in hollow cavi-
ties, and varies in size from the head of a pin to a foot or up-’
wards in diameter. When solid, the masses are marked with:
parallel lines, straight or concentric, sometimes with botly; the
latter forming a border or coating round the straight lines.
The solid pieces are frequently penetrated. by minute stalac-
tites of the same substance; branching through the mass, in a
form perfectly vegetable ; and as these always contain a por-
tion of green earth, it occasions an appearance extremely
similar to moss; which no doubt has given rise to the
assertion of Lanpt, that moss and straw actually occur
in them. I have sometimes found, on breaking the solid
masses, which contained these slender: fibres, the latter would:
séparate from their bed, and leave an impression of their form,—
a tolerable proof that they must have been in a solid state pre-:
vious to their being enveloped in the larger mass. I have ob-
tained very few stalactites, whose centres are not occupied by
this green substance; it. seldom exceeds in thickness the:
twentieth part of an inch, and varies in colour, from a very

Vou. VIL. Kk . dark

258 ACCOUNT OF THE MINERALOGY

dark green, with a tinge of blue, to a pale green, and even &
light straw-yellow. It is always opake. It is not easy to
conceive, that this substance could have existed without some-
thing to support its very delicate fibres; but yet this appears
to be quite evident, from the examination of specimens, and.
consequently adds one more difficulty to the solution of the
formation of Calcedony. _

When calcedony occurs in hollow cavities, they are simply
mamillated, ornamented with stalactites, or lined with crys-
tals. Externally, they are of a very fantastic shape ; but with-
in, the arrangement is more symmetrical. The upper part
forms a kind of dome, with a smooth ‘mamillated surface, or
appended all over with stalactites, which generally hang per-
pendicularly, but sometimes ramify in.every direction ; while
the lower part of the cavity is filled up, so as to present an
horizontal surface or platform, affording a pleasing contrast
with the irregularity opposed to it.

This platform is evidently the result of circumstances sub-
sequent to the formation of the stalactites, as they not only
occasionally penetrate it, but sometimes the horizontal partseems
to have risen to the top, so as to have filled the cavity, and en-
velope the stalactites entirely: This part of the mass also
varies from the rest, by presenting different shades of colour,
forming the onyx, or Band Calcedony of the lapidaries ; it is
often accompanied with semi-opal, white, yellow, and green in
colour, and also with the opake white substance, known by the
name of Cacholong. It likewise often happens, that the upper
and stalactitic part of the cavity is covered over with a second
deposition, forming a distinct coat, which sometimes differs
in colour. Besides the circular arrangement which this pro-
duces in the section of the stalactites, when they are cut across

and

OF THE FAROE ISLANDS: 259

and polished, a radiation of fibres may be observed diverging
from the slender green thread which occupies the centre.

It does not appear as if the form of the stalactites were ow-
ing to the pendulous. position in which they are found, as they
sometimes occur attached by the side; and terminated both
above and below. With respect to»size, they vary, from. the
thickness of a hair to two inches in diameter; but I have not.
found any above four inches in length.

The cavities are often entirely lined with crystallized ‘quartz, .
which always forms a distinct coat, and is sometimes interpo-
sed between the two coats of calcedony. To illustrate these
combinations, I selected a series of specimens, all of them por-
tions of hollow masses. In the first, the quartz is transparent and
crystallized, in the usual form. In the second, the crystals are~
coated with calcedony, but so slightly, that the shape of the
quartz is preserved entire. In the third, the edges of the crystals
are rounded off. In the fourth, the apices are partly converted.
into mamillons. And, in the fifth, the crystallization is entirely
replaced by a. mamillated surface; the quartz being. visible
only in the section of the mass. Nearly the whole of these
changes may be traced in one specimen belonging to Sir
Grorce. Mackenzie. At.one part, the crystallization is nearly
complete, while, at the other extremity, it is perfectly mamil-
lated. I never observed quartz crystals among stalactites,
or stalactites among crystals. The quartz and calcedony al-
ways occur in distinct coats, one or other occupying the whole
surface, and, except very rarely, with perfect uniformity.

Quartz and calcedony is a combination well known to mi-
neralogists ; but before visiting Faroe, I was not aware, that
the latter substance occurred, also intimately connected with
zeolite. Some Danish mineralogists have considered. this sub-
stance as the connecting link between calcedony and opal; a

Kk 2 conclusion:

260 ACCOUNT OF THE MINERALOGY

conclusion I did not find to be justified by the observations
which occurred to us; opal and the mixture of zeolite and
calcedony having uniformly very different aspects.

The first specimen of this description which I procu-
red, is a very interesting one. The outer surface, or that
which lay next the matrix, is formed of radiated zeolite,
which has also been projected into the cavity, in the form of
stalactites. The whole of this is covered over with calcedony,
which is so intimately blended. with the acicular fibres of the
zeolite, that it is nearly impossible to trace the demarcation
between the substances. And, again, upon this calcedony, is
imposed acoating of most slender stalactitic fibres of the same
material. In the centre of the zeolitic stalactites, there is a
point, like that occupied by green earth, in those of calce-
dony, from which the zeolite diverges. Here the zeolite
is infinitely harder than is usual with the varieties of that
substance,—an effect no doubt produced by its intimate con-
nection with the calcedony.

In cavities of this description, we sometimes found quartz
and sometimes zeolite; but the latter does not, like the for-
mer, uniformly occupy the entire surface, being occasionally
dispersed in solitary crystals, among the stalactites of calcedo-
ny, and sometimes, though rarely, accompanied with carbonate
of lime. |

The only variety of crystallized zeolite which occurred in
these cavities, was Apophyllite, presenting two or three very
beautiful varieties of crystallization :

1. In rectangular prisms, terminated at each end by faces set
at right angles to the axis, and deeply truncated on all
the solid angles, so as to form a truncated pyramid,

the.

‘OF THE FAROE ISLANDS. 961

the sides of which would measure about 67°. This is
the Mesotype epointée, fig. 175. of Havy.

2, The same crystal, with the apices of the pyramids perfect ;
may be termed the Pyramidal Apophyllite.

3. When the same crystal is so short in the prism, that the
truncating faces touch, and so broad on the terminal
faces, as to reach the sides of the prism, a cube trun-
cated on all the solid angles is produced.

4, In rectangular prisms, hollow, and diverging at the termi-
nation. This variety, I suspect, owes its present ap-
pearance to decomposition.

In one specimen, I found some of the crystals of zeo-
lite covered with a sheath of calcedony, open at the top,
and partly hollow, owing to the decomposition of the apophy]-
lite. It would be almost endless to proceed, with a detail
of all the peculiarities which occur, in the combinations of these
different substances. I have said enough to mark several cu-
rious circumstances relating to them ; many of which will per-
haps have an effect quite the reverse of affording any clew to-
wards those hidden arts by which the hand of nature has ae-
complished their formation. We have proofs, most unequivo- .
eal, of the igneous origin of the rock in which they are imbed-
ded, and consequently of their own. But granting this, as also
the construction of the cavities, and the production of the sta-
lactites of calcedony, whence came the second coating, which
so frequently occurs, linmg them entirely and uniformly
throughout ? whence the different alternations of quartz and
calcedony ? and whence the substance of those beautiful crys-
tallizations of zeolite I have just mentioned ?

eke

262 ACCOUNT OF THE MINERALOGY

Like all other trap countries, the Faroe islands are intersec=
ted by innumerable dykes. Those we examined were princi-
pally of fine-grained greenstone, and more or less formed of
prismatic distinct concretions. ‘They frequently occur in the
hollows, between hills, and in gulleys which intersect. the
precipices, being, from their proneness to decompose, them-
selves the cause of these indentations. They do not appear to
have any peculiar direction, although they be generally very
nearly perpendicular. Many we perceived cutting the hills-
from top to bottom. Some we could trace from one island
to another; and even where covered with soil, we- often ob-
served their track, by the superiority of the verdure on the-
surface; the dyke, from its looseness of texture, having
acted as a drain, and rendered the bottom more nourishing to
the vegetable root. This circumstance proves how permeable-
these dykes are to.moisture, and helps.to account for the sin-
gular fissures that. often present themselves on the shore..
They are considered by Lanor as marks of some violent con-
vulsion in: nature; and. to a common. observer, they have very
much that. appearaice: The effects of the weather, however,_
without any such assistance; are quite sufficient to accomplish.
this end; nor will its operations. be tardy ; the constant ac-.
tion of the surface-water on the summit, and the continued.
lashing of the wayes at the base, are agents of sufficient power ;,
and we have thus: dykes washed from their sockets, for an ex-.
tent of several hundred feet, leaving: a: atin chasm in. rocks
of enormous height..

Two, of the most singular dykes, we met salads, are Tareas
Thiornivig and Westmanhayn, on the north-west coast of Stro-
moe. The first intersects a mural. precipice, a little be-.
yond Stakken. This: is a double dyke: immediately under

the edge of the cliff, it divides, and. shortly after joins again ;
it,

OF THE FAROE ISLANDS. 263

it then separates a second time; and thé left branch con-
tinues its course downwards to the sea; while that on the
right diverges, and breaks off in a point; a little beyond, but
ssomewhat above the level of this, it recommences, and con-
tinues downwards to the edge of the water, in a line parallel,
but at a distance from the other. Both terminate in caves,
which often occur at the base of dykes.

The other which attracted our attention, is a little south of
the entrance to the bay in which Saxen is situated. At the
top, it cuts the edge of the cliff, in the usual manner. After
descending for some length perpendicularly, it makes a curve
to the left, in the form of a hook, and becomes evanescent.
Within this curve another takes its rise,-and after describing
a figure similar to the letter S, it again vanishes. To this ano-
ther succeeds, somewhat similar in form, but not quite so
regular, commencing and vanishing in the same way; and
from within the lower curve of the last, another sets off; and
from this the dyke continues perpendicularly till it reaches the
water. The cliffs in which these two dykes are, being princi-
pally composed of trap-tuff; the colour of which is dark-brown,
while the dykes themselves are almost black, and of the pris-
matic structure; the contrast renders them conspicuous and
well defined. |

Ihave seen many veins of basalt, but never found one pre-
‘senting features at all analogous to those of the last mentioned.
From the appearance of the tuff in its immediate vicinity, one
would almost imagine, that the whole mass, from top to bot-
tom, not less, I think, than about 1000 feet, had been in a soft
state when invaded by the dyke. In many of these rocks there
is a parallel disposition of the materials observable ; and in
some, myriads of minute particles of zeolite were arranged in
such regular lines, as to give them a decided stratified appear-

ance.

264 ACCOUNT OF THE MINERALOGY

ance. Some such lines existed in this cliff ; which, near the dyke,
were drawn as it were into the curves it has described, which
could not easily have been the case, had the rock been in a so- —
lid state when it was traversed by this dyke.

The soil produced by the degradation of trap-rocks is usu-
ally found to be fertile, and favourable to vegetation. These
islands, however, where no other rocks exist, have no such
happiness to boast of. In Faroe, there is no flat land, on
which the reduced materials can rest; and where not occu-
pied by impracticable cliffs, they present a solid smooth sur-
face, always highly inclined, on which vegetation, by degrees,
arrests the crumbling particles, and in time forms a sward
upon the arid rock. Here, however, from the impenetrable
nature of the mass, no support can be obtained by the vege-
table fibres ; accumulation, therefore, becomes fatal, and, sink-
ing under its own weight, the soil slips from the surface, —
eae the rock in its original naked state.

The hills being placed so near to each other, there are no
valleys to enrich ; consequently, whatever falls from above,
is. swept away by the mountain torrents, and affords no: far-
ther benefit. So slight is this vegetable covering, that it ofter
gave way under our feet, leaving the smooth rock exposed:
This was likewise the case among the more recent debris;
on which, when expecting safe footing at least, we often found
an inclined and slippery surface, covered with wet clay, which
rendered a considerable degree of caution necessary., — It is be-
tween the sward thus formed and. the rock, that the rains
water must find its way. Hence the cold damp. bottom on
which the verdure rests, renders it ‘ataaly unfit for re
or improvement.

Where the torrents ne a down re side of a hill, we had
ah opportunity of observing the smooth and. solid nature of

the

OF THE FAROE ISLANDS. 965

the rock, on which the action of the water had produced no
other effect, than displacing the soil, the course being simply
marked by it on each side; and Lanprt informs us, that there is
no soil in any part of the country above three feet thick.
It would be curious to investigate, whether this smoothness
on the sides of the mountains could be traced to any external
cause, such as that which has been observed by Sir James
Hatt, on Corstorphine Hill, and other parts of this country,
indicating the passage of heavy bodies along the surface.
Near Eide, I observed a very remarkable example of this
description. There the rock was scooped and scratched in a
very wonderful degree, not only on the horizontal surface, but
also on a vertical one, of thirty to forty feet high, which had
been opposed to the current, and presented the same scoop-
ed and polished appearance with the rest of the rock, both
above and below.

Had any doubt respecting the igneous formation of trap
rocks remained upon my mind, previous to my visit to Faroe,
‘it would have been completely removed, by the facts we
there met with, which have been so ably described by my fel-
low traveller. These we first observed in the Island of Nal-
soe, and afterwards at Hide, and at Waaij. The specimens
bearing marks of this phenomenon, which we brought home,
in order to present to the Society, wili sufficiently convey the
same impression to all who examine them. No production of
a furnace can tell its tale in plainer language, nor any slag
bear more distinct marks of the effects of heat.

In Nalsoe, it was only on the surface of one bed of amygda-
loid that we observed these marks of fusion. They were the
first I had seen, and of course created no small degree of sur-
prise. This was distinctly the upper surface of the bed, be-

Vou. VII. Ll ing

266 ACCOUNT OF THE MINARALOGY

ing immediately overlaid by the brick-coloured trap-tuff, pass-
ing into the superincumbent bed. At Eide and Waaij, the-
appearances differed from those of Nalsoe. They did not oc-
cupy the-surface, but were dispersed through the bed, at dif-
ferent elevations, yet all parallel, as if it had been formed of a
multitude of partial flowings, each moulding on the consolida-
ted surface of its predecessor, and extending, as the supply of
fluid matter permitted ; and, so far as we observed, this was
always in the direction of the declivity of the hill or cliff on.
which we perceived them.

By the regularity of the folds wad wrinkles. which characte-
rize their surfaces, and their usual horizontal position, they
seem to have flowed undisturbed ; and although we never met
with any very extensive surface exposed at one place, in con-
sequence of finding them always on the declivity of a hill, yet
we had the most perfect evidence of their passing under the
incumbent rocks, but to an extent of which we could of course
form no estimation. There was enough, however, seen, to
mark it as a fact of a general nature, and one which, more than.
any other I have ever met with, denotes the origin of trap:
rocks.

There is a wide difference between ascertaining the agency
by which a rock has been formed, and the manner in which
that agent has been applied. It is an inquiry perhaps of no:
great utility, but, in prosecuting the one, the other naturally
presents itself, and the inquisitive mind cannot be expected to
stop short, particularly at a point, where; ‘for the first time, it
has met with data quite unequivocal. Here, however, the multi-.
plicity of proof in favour of the former, throws a difficulty of great
magnitude in the way of the latter. Had each bed been the
operation of a volcanic eruption, the appearances of fusion

ot | tvould

OF THE FAROE ISLANDS. 267

would have been confined to the surface, as was the case in
Nalsoe; but when these occur throughout the whole mass, all
in parallel lines, it is difficult to comprehend how the minute
portions constituting a series of distinct and separate flowings, .
could have been produced. From the smallness of their bulk,
it appears evident, that they never were exposed to the action
of a superincumbent ocean, as they could not possibly contain
heat enough to counteract its effects; and if the whole bed
had been in fusion at once, the internal marks, if not oblitera-
ted, would, at all events, have been deranged. In order to.
conceive a bed of lava flowing under an ocean, I should ima-
gine one necessary postulate is, that the bulk of heated matter
must, in all cases, be equal to sustain the whole in a state
of fusion, until it has flowed into the situation it was destined
to fill; and from thence, again, other operations are requisite
to raise it to the station it now occupies, above the level of the
sea.

The extent of the country, the uniform inclination of the
beds, their regularity and symmetry, all present difficulties to
this mode of formation ; and while the igneous appearances in
the rocks of trap, bespeak a source in some near neighbour-
hood, throughout the islands, there is not one spot that can be
fixed upon, more readily than another, as the site of a volca-
no; the highest hills in the country, Slattertint and Skeeling-
feld, being surmounted by beds of trap, nearly horizontal.

To my mind, the subject remains loaded with difficulty. It
is something to have obtained’ such unquestionable corrobora-
tion of the igneous origin of trap. But the circumstances
under which that powerful agent has performed its office, are
to me, I confess, as inexplicable as ever.

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hh et r

VIII. Account of the Structure of the Taste Mountaty, and other
Parts of the Pentnsuta of the Care. Drawn up by Pro-
FEssor Prayrair, from Observations made by Captain

Basit Hati*, R. N. F. R. S. Epi.
(Read 31st May 1813.)

HE Paper which I have the honour of presenting to the
Society, is drawn up from letters written by Captain
Hatu to some of his friends in this country, after a visit made
to the Cape of Good Hope, and an excursion to the Table
Mountain, in July last. I have given the description, as much
as possible, in his own words, and have only connected parts,

which, from the nature ef the communications, were necessa-

rily disjommed from one another. One of the letters being
written to myself, and containing a general view of the whole,
has been my guide for arranging the rest.

Captain Hatz intended to have reduced his observations
into order, for the purpose of laying them before the Royal
Society, which, however, his professional avocations have not
left him leisure to accomplish. In the mean time, as they
make known a new fact in Geology, and one which, though
from analogy, we might suppose that it was somewhere to be

Vou. VIL, P. Ih Mm met

il Then Lieutenant.

270 ACCOUNT OF THE STRUCTURE

met with, has not hitherto occurred, it was thought right to
lay them before the Society; and I have undertaken the ar-
rangment of the materials the more willingly, that the de-
scriptions, though coming forward without the accurate finish-.
ing which the author alone could be expected to give them,,.
do great credit to his skill and judgment, and will, I am sure,
_be received by the Society as a most promising indication of the-
talents of a young and ardent Geologist, from whom much
important information. may hereafter be expected..

The Peninsula of the Cape is. a narrow mountainous ridge;. -
stretching nearly north and south, for thirty or forty miles, and:
connected on the east side, and near its northern extremity,,
with the main body of Southern Africa by a. flat sandy isth-
mus, about ten miles broad, having Table Bay on the north of
it, and the spacious indenture, or rather gulf of False Bay on:
the south. ‘The southern extremity of this peninsula projec-.
ting into the sea, with False Bay on the east, and the ocean on
the south and west, is properly the Cape of Good Hope, and is
the most southern point of the African Continent. At this:
point, the-chain which constitutes the peninsula, though rug-
ged, is lower than: at the north end, where it is terminated by:
the Table Mountain, and two others, which form an: amphi-
theatre, overlooking Table Bay, and opening to the north.
The sketeh. Plate XIII. represents the positions here referred:
to..

Table-Bay is open to the north and west, and is therefore an
unsafe station for ships while the sun is in the-northern hemi-
sphere, and while the wind blows strong, as it always does, at
that season, from the north-west. The ships then rendezvous
in. False Bay, where they have complete shelter from the pre--
yailing wind.. The ship in which Mr Hatt was, arrived on the:

coast

PHO Mey ara es

s* |

Royal Socidy Frans, Vol 7 Lage P70.

SRET Cay

of the
PENINS UL
of the
CAPs

\\

i
fii”

hae

Sa

Cape False

PLATE XIill.

20

oSeal Island

Noah's Ark

NY Simons Bay 77

eo
:

‘OF THE TABLE MOUNTAIN. 2Tl

voast in July ; it was obliged to go round the Cape to the lat-
ter station ; and as they stood close in-shore when they work~
ed into the Bay, he had an opportunity of seeing the general
distribution of the strata in the peninsula, which seemed near-
ly horizontal, but dipping somewhat to the south.

On the east side of False Bay, the outline of the hills is ex-
tremely rugged, often running into sharp conical peaks, and al-
together having the aspect of extreme asperity and barren-
ness.

The three hills which terminate the peninsula on the north,
are the Table Mountain in the middle; the Lion’s Head, some-
times called the Sugar Loaf, on the west side ; and the Devil’s
Peak on the east. The Lion’s Head, which is about 2100 feet
high, is separated from the ‘Table Mountain by a valley, that
descends to the depth of 1500 or 2000 feet below the summit of
the Table Mountain, which is itself 3582 feet above the level
of the sea. On the west of the Lion’s Head, the ground, after
falling, rises again, forming an inconsiderable elevation, known
by the name of the Lion’s Rump, from which the ground de-
scends gradually to the sea. The amphitheatre, formed by
these three mountains, is about five or six miles in diameter,
in the centre of which is placed the Cape Town. The situa-
tion is magnificent, with the sea stretched out before it on one
side, and the perpendicular cliffs of the Table Mountain over-
hanging it on the other. The Town itself is built with
uncommon regularity, but has so many squares, gardens
and trees interspersed, that the stiffness and formality of
streets, either parallel or cutting one another at right angles,
is entirely taken off. All round the town, on the land
side, up to the base of the cliffs, where the piles of ruins
from above effectually prevent cultivation, the ground is

Mm 2 covered,

272 ACCOUNT OF THE STRUCTURE

covered with gardens, laid out in the Dutch style. In
this. space, of course, the rock is nowhere to be seen. Exactly
in the middle of the perpendicular face of the Table Moun-
tain, a ravine indents it to a considerable depth. | Down this
a stream constantly runs, which is often suddenly swelled into
an impetuous torrent, and has acted very powerfully in clear-
ing away the earth and rubbish, and in laying bare the rock to
a considerable extent. _The.ascent to the top is by this ravine,
and, though the distance is not great, is a work of consider-
able labour, on account of the steepness, and still more, on ac-
count of the vast fragments of rock, which one must clamber over
continually, and which seem so exactly poised, that the least
addition to the weight of the projecting side, must precipitate
them to the bottom. The cut thus made in the mountain is
about. twenty or thirty yards deep, and from ten to fifteen
wide at the bottom, though, at the upper part, the walls are not
distant from one another by more than eight or ten feet.

Captain Hatt, in a letter to his Sidhe’ Sir James, gives the
following account of his first ascent.

“ The day before yesterday, I set out on an excursion to the
‘Table Mountain, with the ardour and impatience that you, I
have no doubt, on similar occasions, have often experienced.
I set out with the intention of following the course of a stream
that descends from the ravine in the face of the mountain. For
a considerable distance at the bottom of the mountain, the soil
covers the rock; and a little higher up, I found large fragments
of sandstone, and now and then a block of granite, which had
come down from above. I came, after a short ascent, to a
space where many yards of the, rock were laid perfectly bare,
and I found myself walking on vertical Schistus, or on what
might be called Killas. This rock was in beds highly inclined,

and.

OF THE TABLE MOUNTAIN. 273

and stretching from east to west, which is nearly the direction
of the mountain. It was not always easy to ascertain, which
way these beds inclined. They were often almost vertical, and
in some places I found them inclining from the mountain. On
looking forward a little higher up, I saw another portion of
rock that was also laid bare, and which appeared to be Granite.
I had now no doubt of reaching in a few minutes the precise
junction of the two recks, and I ventured to: predict to my
companion, who was not a little surprised at the pleasure I
seemed to feel on this occasion, that we should immediately
see veins from the main body of the granite, penetrating into
the rock on which we were now standing. In this I was not
deceived; the contact was the finest thing of the kind I ever
saw; the Windy Shoulder * itself not excepted. The number
of veins that we could distinetly trace to the main body of the
granite was truly astonishing ; and the ramifications, which ex-
tended on every side, were of all sizes, from the breadth of
two yards to the hundredth of an inch. Masses of killas, cut
off entirely from the main body of that rock, floated in the ora-
nite, without numbers, especially near the line of contact, and
the strata appeared there broken, disordered, and twisted in a
most remarkable degree: )

_ Near this place I found.a mass of killas in a:state of de
composition ; it had crumbled away, and left the granite dykes
with many of the slender ramifications standing. The word
ramification does not, however, properly express the nature of
these smaller dykes ; which are not branches, but plates or thin
slender walls.. There is nothing here that might not be ex-

pected,

* The spot which Mr Hau refers to, is on the side of’ Loch Ken in Kirk-
eudbrightshire, and is remarkable for veins of Granite, of the same kind with

those here described. An account of it will be found in the preceding part of
this volume, p. 99.

QTA4A . ACCOUNT OF THE STRUCTURE

‘pected, on finding a vein partly stript of the containing rock;
but as a specimen of this sort had never occurred to me before,
I thought it worth mentioning.

“ From this point, following up the course of the stream for
about -300 yards, I found the whole a solid mass of granite.
The granite is characterised by large crystals of felspar, which,
indeed, is true of all the granite which I met with at the
Cape. Besides quartz and mica, large masses of hornblend en-
ter occasionally into the composition of this rock.

“ After ascending about 300 yards farther, I came to a line
where the granite ceased, and was succeeded by strata of su-
perincumbent Sandstone. These strata were horizontal, and
without any’symptom of disturbance or violence whatsoever.
There was not.a shift nor a vein; and this junction formed a
most marked contrast with that which we had left below.

‘“‘ Looking round from the point where I now stood, to all the
parts of the amphitheatre, in the centre of which I was placed,
I could trace the same line of junction, extending horizontally
on every side.

“ From this point, where the sandstone was first discovered,
for about 150 or 200 feet perpendicular, the rock continued of
the same kind, viz. a red sandstone, in horizontal beds of no
great thickness. From thence all the way to the summit the
sandstone was of a much more indurated kind, quite white,
and having pieces of water-worn quartz imbedded in it, from
the size of a pea to that of a potatoe. The top is a plane of
about ten acres, somewhat uneven, though, on the whole, near-
ly level. The weather acting very powerfully in this exposed
situation, has worn holes, and laid open the strata in some
places to a considerable depth; and the cement of the sand-
stone being softer than the included masses of quartz, these
last, when they are exposed at the surface, are always pre-

sented

OF THE TABLE MOUNTAIN. 275°

‘

sented with considerable relief. From the same cause, the bot-
tom of every excavation is covered with a little beach of
quartz pebbles, which have belonged to strata now wom
away.

“ The day was remarkably fine, so that the prospect from the
top of the mountain could hardly be seen to greater advan-
tage than at this moment. It was, indeed, uncommonly grand,
and the interest was heightened by the novelty of the objects,
- and, perhaps, not a little by the reflection, that the point on
which we stood is so remarkable in the constitution of the
earth’s surface, and so memorable in the history of nautical dis-
covery. A carpet of the richest heath embellished the sum-
mit, and I sadly regretted, that my knowledge of botany was-
not sufficient to enable me to describe the beautiful varieties:
of that plant for which the Cape is so justly celebrated.

“ The same structure that is found in the Table Moun-
tain, extends to two others in its vicinity; particularly the
upper part of the Lion’s Head, which consists of sand-.
stone. Under the sandstone is found granite; and on the
north side, when you descend farther, you come to killas.
in vertical beds, which extend farther to the eastward, forming:
the Lion’s Rump, where the strata are not strictly vertical, but
incline to the north, at an angle of about 8° from. the perpen-.
dicular; their direction or stretch is across the peninsula, or
from east to west, as at the Table Mountain. I had not time
to undertake a particular examination of the Devil’s Peak.
The upper part of it is certainly composed of sandstone; the:
junction of which with the granite is distinctly visible from.

many places..
«“ The same structure, with the variation of some:circumstan-

ees, seems to take place all. over the peninsula. The line of
the junction of the granite and the sandstone, lowers in its le-

vel, however, as you approach the southern extremity, and the:
killas:

276 ACCOUNT OF THE STRUCTURE

killas at last diangiienad entirely... I uniformly found the rock,
whith the-sea washed towards the south part of the peninsula,
to-be granite, and five or six yards higher was the sandstone.
That which lay next the granite, was the red, as before, and
above that was the white and more indurated sandstone; nor
did it seem that there was much difference between the
thickness of the sandstone mass here and at the Table Moun-
tain. I must not omit to remark, that at the entrance of Si-
mon’s Bay, a creek in the west side of False Bay, where our
ship lay, there rose from the sea an oblong rock of granite,
about ten yards long, four or five yards wide, and eight or ten
feet high, called Noah’s Ark: abreast of this, on the beach, I
found two whin dykes, a foot wide each, cutting the granite.

“ Were it not,” continues Captain Hatt, “ too great presump-
tion in me to step out of the province of simple description, to
wander in the regions of theory, I would propose as a conjecture,
‘That the great mass of Sandstone which forms the summit of
the Table Mountain, and of all the hills in the peninsula, had
been raised from its original horizontal positien, to the eleva-
ted situation it at present occupies, by the Granite forcing it up
from below; that the rest of the peninsula had been raised
in the same manner, but not so high, or that it had been lift-
ed up a little more on the east side than the west. The high-
ly inclined position of the killas, at the base of the Table

Mountain, and the disjointed nature of its junction with the

granite, seem conclusive as to its having undergone a great
change; while the veins of granite which traverse the strata,
both by their appearance when they insulate the fragments of
killas, and by their minuteness of ramification, seem to have
been in a state of fusion, accompanied by very considerable
violence.”

Thus

4"

‘OF THE TABLE MOUNTAIN. On7

Thus far Captain Hari; and the concluding remark, so far
from requiring apology, seems to me a very fair interpretation
of the phenomena he has described. Conformably to this view
of the matter, I would only farther remark, that the phenomena
here described point out two separate epochas, distinguished by
very different conditions of the substances which now compose
the peninsula of the Cape. That peninsula, it now appears,
is a wall of granite, highest at the northern extremity, and
lowering gradually to the south ; faced, at its base, with grau-
wacky, and covered, at its top, with a platform of horizontal
sandstone. The penetration of the killas or grauwacky, by
veins from the mass of granite which it surrounds, proves that
the killas, though the superior rock, is of older formation than
the granite. The granite, therefore, is a mineral that has come
up from below into the situation it now occupies, and is not
one of which the materials have been deposited by the sea in any
shape, either mechanical or chemical. It is a species, there-
fore, of subterraneous lava, and the progeny of that active and
powerful element, which we know, from the history both of the
present and the past, has always existed in the bowels of the
earth.

The introduction of the oranite into the situation it now oc-
cupies, must have taken place while the whole was deep under
the level of the sea: this is evident from the covering of sand-
stone which lies on the granite, to the thickness of 1500 feet ;
for there can be no doubt whatever that this last was deposi-
ted by water. After this deposition, the whole must have been
lifted up, as Captain Hau supposes, with such quietness and re-
gularity, and in so great a body, as not to disturb or alter the re-
lative position of the parts. Thus. the granite is shewn, I think |
with great probability, to be newer than one of the rocks in-
cumbent on it, and older than the other. I know not that we
have ever before had an example of a fact which so directly ascer-

Vou. VII. P, I. Nn tains

278 ACCOUNT OF THE STRUCTURE, &c.

tains the place which granite really occupies, in respect of the
other parts of the mineral kingdom; it is one that from ana-
logy might be expected. to take place, and it is highly favour-
able to the opinion, that granite does not derive its origin from

aqueous deposition. It seems, indeed, to be an instantia cru-

cis, with respect to the two theories concerning the formation,
of rocks.

The sandstone, which covers the granite at the Cape, has the
appearance of being a very extensive formation; and is pro-
bably a part of the same which Barrow, Cisne and
other travellers, have mentioned as composing many of the
principal mountains over a great tract of Southern Africa. The
tenuity of the parts holding together large masses of that rock,

and indicating a singular approach to equilibrium between.the —
causes that produce, and those that resist decay, was observed

on the summit of the Table Mountain, as already mentioned;
and similar appearances excited the surprise of the two tra-
vellers just named, in some of the most inland tracts which
they. visited. :
Plates XIV. and XV. are representations of veins of eranite

connected with the main body of that rock, and penetrating

into beds of killas or grauwaky, which are nearly vertical. ;

LY te ae

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foyal Society Trans. Fol 7. Page 27d,

Sorted .

the Killas, the Staitdication becomes
very wndistinct, and frequently berms
ansuterably more than ary of these |
Sketches represent, jnost of the

detached fragments are Contoraea ,

|
Lr many of the Fes which traverse

and appear as if they had beer

|

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——l |
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GRANITE VEIN IN THE TABLE MOUNTAIN A YARD £ A HALF WIDE.

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IX. Comparison of the North Polar Distances of Thirty-eight

Principal Fixed Stars, on the 1st of January 1800, as de-
termined by Observations made at Greenwich, Armagh,
Palermo, Westbury, Dublin, and Blackheath. By
§. Groomsriner, Esq. Blackheath, F.R.S. Lond.

Communicated by Dr Brewster.
[Read 16th November 1812. }

BY comparing the longitudes and latitudes of the fixed stars,
as computed from their right ascensions, and north polar
distances, determined by observations made at distant periods,
Astronomers have been enabled to ascertain, with the utmost
accuracy, the precession of the equinoxes. The great accuracy,
however, which has lately been introduced into the construc-
tion of astronomical instruments, and the more general culti-
vation of Practical Astronomy, will hereafter be the means of
ascertaining the minute changes in the places of the fixed
stars, which have been denominated their proper motion, and
which, probably, arise from a motion of the solar system in

_ absolute space.

The observations made at Greenwich during the last fifty
years, have been chiefly upon thirty-six of the principal fixed
stars. Observations were also made upon y Draconis, as being

near

280: €OMPARISON OF OBSERVATIONS. ON

near the zenith, for determining the collimation of the qua-
drant ; and upon Polaris, to determine the distance of the pole:
for the co-latitude. In consequence of the erection of circular
instruments in several fixed observatories, since the year 1790,
they have been employed in. observing the same thirty-eight
fixed stars, and it is from the results of these observations that
we have been enabled to make the. comparison contained in
the following Table.

‘The first column: contains the observations made by Dr Mas-
KELYNE at Greenwich, with an eight feet mural quadrant: The
second, contains the observations. made at Armagh by Dr Ha-
MILTON : The third, those made at Palermo by M. Prazzz, with:
a five feet circle: The fourth, contains those made by Mr
Ponp at Westbury, with a two and a half feet circle: The fifth,
contains the mean of the observations made by the preceding,
circular instruments, as deduced by Mr-Ponp: The sixth, con-
tains the observations made by Dr Brinxtey at Dublin, with
an eight feet circle: And the seventh, contains the obserya-
tions made at Blackheath, by the author of this paper, with a.
four feet mural circle.

The: differences among ‘the results obtained by these instru=
ments, may-arise from various causes ;—from errors in the di-
vision of the instrument. ;—from. the assumption of different
formule of refraction, which will affect all the zenith distances.
as well as the co-latitude ;—from a probable deviation of the
plumb-line ; and fromthe uncertainty of the proper motion of
the stars, in reducing to the same-epoch the observations made
from 1792 to.1810, the quantity of which is very considerable
in Arcturus and Sirius. The mural circle of six feet, erected.
at Greenwich in 1812, may be expected to reconcile several of -
these: diserepancies, leaving’ ‘doubtful - ont the small quantity.

that.

THIRTY-EIGHT PRINCIPAL FIXED STARS. 281

that may be’ supposed to arise from the deviation of the plumb-
line.

The observations made at Palermo differ from those given
by Mr Ponp, in his paper on this subject; having been co-
pied from the recent catalogue of M, Piazz1, published in

1808. |

TABLE

| 2

STAR. Greenwich. Armagh.
‘Polaris, © es 14S SSST PP? 45° SS
y Draconis, 38 28 53.0] 38 28 53.8
Capella, 4413 21.6] 44 13 21.5
« Cygni, 45 25 41 .5| 45 25 39.5
a Lyre, 51 23 41 4] 51 23 37.4
... Castor, 57 41 14.4] 57 41 9.8
- Pollux, 61 30 10.2] 61 30 4.6
8 Tauri, 61 34 31.3] 61 34 32.8
« Andromede, 62 046.2) 62 045.5
« Corone borealis.) 62 36 10 .9| 62 36 7.9
« Arietis, 67 29 20.7] 67 29 22.7
Arcturus, 69 46 8.5] 69 46 11.8
Aldebaran, 73 5417.3) 73 5419.1
& Leonis, 74 18 35 .3| 74 18 34 9
e Herculis, 75 22 7 .4| Noobservation
« Pegasi, 75.51 57 .8| 7 52 13
y Pegasi, 75 55 S37 .1| 7% 55 38.4
Regulus, TF eR Di TE. SSB
« Ophiuchi, 77 16 54 .9| 77 16 54.3
y Aquile, 79 51 44 .6 | Noobservation
« Aquilz, 81 38 53 .0| 81 38 51.8
z Orionis, 82 38 31 .8| 82 38 33 .0
« Serpentis, 82 56 2.3] 82 56 1.0
6 Aquile, 84 4 52 .2| No observation
Procyon, 84 16 18 .5| 84 16 20 6
« Ceti, 86 42 7.3) 86 42 8.7
B Virginis, 87 6 27 .6| 87 6 30.4
« Aquarii, ald 2) Oe er 60 2
a Hydre, 97 47 50.9) 97 47 50.8
Rigel, 98 26 30.7| 98 26 35.1
Spica Virginis, |100 6 39 .0.100 6 41.0
12 Capricorni, 103 6 46 7 No observation
2« Do. 103 9 5.4:103 9 15.8
1x Libre, 105 9 13.9 No observation |
2« Do. 105 °11°.58 .0 110512). 3 8
Sirius, 106 26 58 .9|106 27 7.1
Antares, 115 58 18 .7;115 58 29 .4
Fomalhaut, 120 40 36 .5| No observation

~ + ¥° 45/36".21

Uicul 9 North Poldr Distance of Thirty-eight principal

Palermo.

51 23 37.8

57 41 14.
61 30 11
61 34 32.

4
16

86 42
87 62
v1 97
97 47
6 26

106 27 5.0
115 58 24.9
120 40 37.6

283

Fixed Stars, on 1st January 1800.

Westbury. Mr Ponn’s Dublin.

mean

- Blackheath.

———

ee,

—S=_

Polaris, 1° 45’ 36:2 1° 45’°35".0} 1°45’35".'70} = 1°45'35".01
y Draconis, 38 28 53.6 | 38 28 53.0) 38 28 53.11) 38 28 55 .96
Capella, 44 1318 4 | 44 13 19 4] 44 13 19.79) 44 13 19.51
« Cygni, 45 25 36.9 | 45 25 38 .2| 45 25 49 .26| 45 25.42 .08

_ « Lyre, 51 23 36.1 | 51 23 36.7) 51 23 39 .17| 51 23 40 44)
Castor, “BT 41 14.2 | 57 41 13 6 "BT 41 12 .92) 57 41 16.58];
Pollux, 61 30 13.9 | 61 30 12.6} 61 80 10 .83| 61 80 13.39

. & Tauri, |, 61 34 33.9 | 61 34 33.6] 61 34 31 .12| 61 34 35 45
« Andromede, 62 050.2 | 62 O 47.8) 62 0 49 47) 62 O 52.16)
« Coron borealis, 62 36 13.3 | 62 36 10 .4| 62 36 9.99] 62 36 16 .63|
a Arietis, . 67 29 21.1 “67 29: 21 er "67 29 23..89| 67 29 24 .60
Arcturus, 69 46 $8.0 | 69 46 10.2] 69 46 12 .57| 69. 46 13 .29
Aldebaran,,.. ~ 73 5416.0 | 73 5417 .5| 73 54 16.85) 73 54 21 .57
@ Leonis, %4 18 33.1 | 74 18 34.0] 74 18 38 .79| 74 18 38.19
# Herculis,. No observation | No observation| 75 22 12 .33| 75 22 18 .05

—————— aan 1

—

— |

« Pegasi, “75 51 58.6 | 75 52 0.6| 75 52 3.76| 75 52 5 86
vy Pegasi,. 75 55 37.6 | 75 55 39.3] 75.55 41.49) 75 55 45 .93
Regulus,. 17 334.7) 77 3 34.7] 7% 3.39 00) 77 3 41 .53
« Ophiuchi,. 77 16 54.2 | 77 16 54.0| 77 1658.68) 7717 2.85
y Aquilez, No observation | No observation|. 79°51 46.50] 79 51 51 .82
« Aquile, §1 38 52.3 | 81 38 52.7) 81 38 54.47) 81 38 59 .50
' Orionis, 82 38 32.3 | 82 3S 32.7) 82 35 32 .45| 82 38 35 .97
« Serpentis, 82 56 3.1 | 82:56 3.3| 82 56 3.42] 82 56 10 .66
' 6 Aquile,. No observation | No observation| 84 4 51.80} 84 4 58 .90
Procyon, 84 16 22.5 | 84 16 21.6) 84 16 22.00) 84 16 25 .24
« Ceti, 86 4211.4] 86 42 10.2] 86 42 10.28| 86 42 15.07
6 Virginis, Noobservation| 87 6 29.3] 87 6 26.58| 87 6 82.52
« Aquarii,. 9b 17 6.0) 91.17 5.4) 9117 6 .24|°91 17 8.89
« Hydre,, 97 AT 54.8 | 97 47 53.6) 97 47 53.00) 97 47 59 .67
Rigel,. 98 26 38 .2.| 98 26 36.3) 99 26 34 .58| 98 26 39 .50
Spica Virginis, |100 6 44.8 |100. 6 42.9/100 6 43 .06)100 6 47 37
lz Capricorni, | No observation | No observation|103 6 49 .94|103 6 55 .62

Qu Do.

103 ..9 10-.F )103 .;91; 9 8,103. 9 9 .54
1. Libre,

No observation | No observation| No observation
No observation|105 12 3.91105 12 1.80

oe

106 27 4.41106 27 5.71106 27 3.55
No observation|115 58 27 .8/115 58 24 .30
No observation | No observation) 120 40 42 .44

103 9 12.34
105. 9 27 .82}
105 12 7.60

106.27 ©7, BT
115 58 29 .62
120 40 44 .22

i

ere.
4

me,

X. On the Optical Properties of Sulphuret of Carbon, Carbo-
nate of Barytes, and Nitrate of Potash, with Inferences
respecting the Structure of Doubly Refracting Crystals.
By Davin Brewster, LL. D. E.R. S. Evy. & F. A.S.E,

(Read February 7. 1814.)

r I examining the choise shied light ean during it its
_L passage through transparent bodies, we not only receive in-
formation respecting the properties of that mysterious agent ;
but we are in some measure made acquainted with the compo-
sition of the substances themselves, and with the manner in
which their ingredients are‘combined. The optical phenome-
na, therefore, which bodies exhibit in their action upon light,
are so. many tests, to which the philosopher may have recourse,
either in supplying the place of chemical analysis, or in cor-
_recting and modifying its results. A difference in the optical
properties of two bodies, is generally an infallible indication of
_a difference in their elementary principles; and whatever con-
fidence we may place in the skill of the chemist, or in the ac-
curacy of his methods, the mind can never rest satisfied with
_the results of an analysis which is. directly opposed by optical
phenomena.

Vor. VII. P. II. Oo Te

286: ON THE OPTICAL PROPERTIES

It is highly desirable, therefore, that. the Chemical Philoso-
pher would avail himself more frequently of the agencies of
light m the prosecution of his inquiries. The various products
' to which his attention is constantly directed, cannot always be
preserved for subsequent examination, and can seldom be pro-
cured, by the Experimental Philosopher.. An opportunity is-
thus lost of confirming his own results, and of contributing
most essentially to the progress of optical knowledge. It is by-
the alliance, indeed, of Chemistry with Optics, that great revo-
lutions are yet'to be effected in. Physics’; and'the time is pro-.
bably not very distant, when, by their united efforts, we shall:
be able to develope those mysterious relations among the ele-
mentary principles of matter. which. hypothesis has. scarcely:
ventured to- anticipate.

In the following paper, I propose to. describe the optical
properties of Sulphuret of Carbon, Carbonate of Barytes, and
Nitrate of Potash, and to ateaer the conclusions to which.
some of these properties lead, respecting the structure of dou-.
bly refracting ari |

x -
I. Sutpuurer or CarBon.

This eearlestle fluid was lately discovered by Lamrantvs..
It is pure and colourless like water; has a specific gravity of
1.272; is remarkable for its extreme volatility’; ; and is compo-

sed of 85 parts of sulphur, and 15 of carbon. ’

Owing to the great length of spectrum which. this substance-
produces, I found ‘considerable difficulty in measuring the.

mean index of refraction. By taking the bisecting ray beyond

the green rays, and very considerably advanced. g: sol the blue-
space, I obtained. the following results :

~~ Angle:

OF SULPHURET OF CARBON. 287

Angle of the prism, 8°10
Angle of refraction, 5° 38
Refractive power, _ 1.687

By considering the bisecting ray, as passing through the green
space, and near its confines with the ene a following mea-
sures were obtained :

Angle of the prism, “ge 10°
Angle of refraction, ==» 55° 27
Refractive power, _ 1.6632

As the sulphuret of carbon has nearly the same action upon
the red and green rays, as balsam of Tolu, I have no doubt but
that the bisecting ray is considerably advanced upon the blue
space, and that the mean index of refraction is nearly 1.680.

A prism of flint. glass, with a refracting angle of 20° 53’,
corrects the colour produced by a prism of sulphuret of car-
bon, having a refracting angle of 8° 10:; the light being inci-
dent perpendicularly upon the fluid “Ata Hence it follows,
that the dispersive power of the sulphuret, or the value of

is 0.115, R being the index of refraction, age d the part

dk
R—1
-of the whole réfraction,to which the dispersion is equal; and
_ that the refractive power of the extreme red ray is 1.623, and
the refractive: power of the extreme. blue ray 1.7377..,
From these experiments we conclude, that the sulphuret of
dail exceeds all fluid bodies in refractive power, surpassing
even flint-glass, topaz and tourmaline ; and that in dispersive
power, it exceeds every fluid substance, except oil of cassia, hold-
img an intermediate place between pheepharis and balsam of
Tolu.:
‘These relations will be better destained from the, following
short Tables :

Oo 2 Refractive

288 ON THE OPTICAL PROPERTIES

Refractive Powers.

Sulphur, native, 2.115,
Boracite, - 1.701
Sulphuret of Carbon, 1.680
Tourmaline, - 1.668
Blue topaz, = 1.636

Flint glass, =~ d,G16,

Dispersive Powers;

Oil of cassia, - 0.139"
Sulphur, ~ - 0.130
Phosphorus, - 0.128
Sulphuret of Carbon, 0.115
Balsam of Tolu, - 0.103
Flint glass, =. 0.052-

Although oil of cassia surpasses the sulphuret of carbon in
its power of dispersion; yet, from the yellow colour with which
it is always tinged, it is greatly inferior to the latter, as an op-
tical fluid, unless ih cases whiere a very thin-concave lens is re-
quired. The extreme volatility of thesulphuret. is undoubted-
ly a disadvantage to which the oil is not liable; but as this vo-
latility may be'restrained, we have no: hesitation\in consider-
ing the sulphuret of carbon, as a fluid of great value-in optical
researches, and which may yet be of incalculable:service in the
construction of optical instruments. Ail other fluids are sepa-
rated from these two, in their ‘optical properties, by an immense
interval; and hence we are of opinion, that oil of cassia will

yet.

OF CARBONATE OF BARYTES. 289

yet be found to consist of ingredients as remarkable as those
which enter into the. composition of sulphuret of carbon.

‘HL. Carzonate or Barytes.

The native Carbonate of Barytes possesses, like the agate, the
remarkable faculty of forming two images, one of which is bright,
and the other nebulous: The shapeless appearance of the
agate; its heterogeneous: and imperfect structure, and its ano-
malous character in- the. mineral kingom, corresponded. well
with the singularity of its optical properties, and discouraged
the anticipation of analogous phenomena, in-minerals ofa more
perfect structure. I was, therefore, surprised, to find the same
character in carbonate of barytes, a mineral which has a re-
gular: crystalline form, and possesses two distinct refractive
powers. The index of refraction for the perfect or least refrac-
ted image is 1.540; and its dispersive power 0.0285.

In order to observe with accuracy the phenomena: presented
by- the carbonate of barytes, I: formed nine prisms,: cut in
different directions, from the same specimen. In one of these
prisms, which was~bounded by planes parallel tothe strice or
longitudinal joints, the least refracted: image was extreme-
ly distinct, while: the other was a faint nebulous image, of
a brownish-red' hue. It was small and round, and the intensi-
ty of its light was inconsiderable, when compared with that of
the bright i image. |

When the image of a candle polarised. by reflection, was
viewed through this prism, having the longitudinal joints pa-
tallel to the plane of reflection, the light which formed the
bright image of the candle was wholly reflected, while: the
nebulous light alone, penetrated the mineral.. But when the

longitudinal.

‘290 ON THE OPTICAL PROPERTIES

longitudinal joints were perpendicular to the plane of reflec-
tion, the light image became extremely distinct, in conse-
quence of the nebulous light having now refused to penetrate
the prism.

In a second prism, the nebulous, or most refracted image
‘was more luminous than in the first, and approached to a defi-
nite form; the general shape of me candle being distinctly vi-
sible. |

In a third prism, the nebulous image was more luminous
than in the last case, and the form of the candle still more di-

stinctly seen ; ‘but it had now the appear ance of an assemblage
of incoincident i images.
In a fourth prism, in which the plane of refraction was pa-

rallel to the longitudinal joints, both the images were imper-'

fect, and the most refracted image was extremely faint. By
inclining the prism, an image appeared on each side of ‘the
least refracted image; but they were polarised in the same
manner, and were probably analogous to the two images which
are frequently seen in specimens of calcareous spar.

In a fifth prism, which was formed by planes nearly per-
pendicular to the longitudinal joints, four images were plainly
visible, all of which were imperfect, and consisted of circular
arches of nebulous light. The two middle ones, which were
the principal images, were equally luminous, and were polari-
sed in an opposite manner, like all other double images; but
each of the two outer images was polarised in the same man-
ner as the bright image farthest from it. The most refracted of
the two principal images, was in this case the most perfect of
the two, and exhibited a degree of prismatic colour so much
greater than the other, that it obviously belonged to a higher
cenedee power. When the light enters the prism, and emer-
ges from it at equal angles, the four images are not distinctly

separated,

OF CARBONATE OF BARYTES. 291

separated, and are oe imperfect. When the angle of
incidence at the first surface of the prism is increased, the
images become more and more distinct, and better separated ;
but, by diminishing the angle of incidence, all the images ap-
proach one another, and are confounded into one mass of ne-.
bulous light. |
With a plate of Carbonate of Barytes, which. was about fio.
tenths of an inch thick, and which had its surfaces at right
angles to the direction of the longitudinal joints, the image of
a candle was a large circular mass of light, when the incidence:
was perpendicular. ‘By inclining the plate, this. mass was chan-
* ged into an annular image: By increasing the inclination, it as-.
sumed the form of a crescent, and at a. considerable angle of.
incidence, it was. separated into three imperfect images, or cir-
cular arches of nebulous. light, similar to those which were
seen with the fifth prism. The middle image, which was the
brightest, consisted of the ordinary and extraordinary image,
which were not. separated, in. consequence of the parallelism of
the refracting surfaces. In. one position of the plate, these-
arches. were crossed by, other three. similar, arches, inclined to
the first at an angle of 10° or 12°. |
‘The phenomena which. have now been described, differ in
several respects from those which are presented by the agate.
In the Carbonate of Barytes, the two images are distinctly se-
parated, and. are, therefore, formed by two separate refractive
powers ; whereas in the Agate, the bright image is placed. in
the centre of the nebulous mass. In the Carbonate of Barytes,
the imperfect image occupies a small space; but.in the Agate,
it is an elongated mass of light, extending about 71° in length,
and about 1° 7’ in breadth, on each side of the bright image.
_ These differences, however, are probably owing to the different
ways in which the two minerals have been cut; but it is not
easy

992 ON THE OPTICAL PROPERTIES

easy to submit this point to direct experiment, on account of
the difficulty of procuring a mass of agate, from which a varie-
ty of transparent prisms could be obtained. It follows, how-
ever, from the theory of the depolarisation of light, which I
“have explained in another place, and which is supported by all
the evidence which any theory can possess, that the specimens
of agate which depolarise light must necessarily form two di-
stinct images,—a phenomenon to which we have found a rapid
‘approximation in the carbonate of barytes. |

The property which has now been explained, forms a simple .
and infallible mineralogical character of the striated carbonate
of barytes ; and is particularly valuable to those who have been
perplexed by the numerous marks with which some writers
have laboured to distinguish it from its kindred minerals. The
assistance, indeed, which optics affords in discriminating mi-
nerals, is of the most extensive kind; and it is much to be
wished, that mineralogists would exchange many of their vague
distinctions for those unambiguous characters which bodies ex-

‘hibit in the modifications they impress upon light.

The Abbé Havy has, in some measure, begun this reforma-
tion, and has set a brilliant example of what may be effected
by the aid of mathematical and physical acquirements. In his
admirable work on Crystallography, which has never been duly
appreciated in this country, he has created a new science, in
which he has shewn how to determine the integrant molecules
of crystallised bodies ; and how, from a few primitive forms,
may be derived that endless variety of secondary crystals which
adorn the mineral kingdom. The recent discoveries which
have been made in optics, enable us to give a new direction to
these interesting inquiries ; to determine the forms, and even
the angles of crystals, from their optical properties ; and out of
a mass of shapeless fragments, to reconstruct an artificial crys-

tal,

‘OF NITRATE OF POTASH. 293

zal, of which all the parts shall have the same relation as they
_had in nature to the axes and sides of the primitive crystalline
_ form.

TIL. Nirrate or Porasu.

This salt possesses the most remarkable optical properties
of any crystal that is at present known, and its various actions

upon light are of the most spomseloyp and mRSEIEHYE charac-
~ ter.

The crystals which. I pcre were all Lien si hexae-
dral prisms ; and the light was transmitted through two natu-
ral faces, separated by another face, so that they were inclined

; to each other at an angle of about 60°. . This inclination is by
no means convenient for measuring refractive and dispersive
powers ; but I attempted in vain to form artificial faces incli-
ned at a less angle, and. those means which Thad found suc-

cessful with other, soft prvatalt completely failed when applied
to this salt.

When a candle was viewed. through the nitrate of potash, I
observed a double refraction very much greater than that of
calcareous spar,—a phenomenon which gave me the more sur-
prise, as the Abbé Havy, who examined many splendid cry-
stals of this salt, ascribes to it the property of simple refrac-
tion.

The least refracted i image Ww was a a circular mass of white ne-
bulous light, condensed at its centre, into a very faint image of
.thecandle, but without any strong prismatic tinge ; while the
light which had suffered the greatest refraction, formed a di-

stinct and highly coloured image. The great 5 sale between
Vou. VIL P, I. jo barRyp the

294 ON THE OPTICAL PROPERTIES

the two images; the achromatic nebulosity of the first, and the
distinctness and deep colours of the second image, formed al-
together a singular phenomenon, and, at the same time, afford-
ed an ocular demonstration of the existence of two dispersive
powers in doubly refracting crystals.

The following measures of the refractive powers.of the two
images were taken with the greatest care:

Angle of the prism, - 60° 21,
Angle-of refraction for the 1st image, 24° 8°
Angle of refraction for the 2d image, 38° 54
Index of refraction for the-Ist image, 1.3374
Index of refraction for the 2d image, 1.5156.

In order-to-confirm these results, I formed a new prism, and
obtained the following measures :
Angle of the prism, a a ee
Angle of refraction for the Ist i image, 24° 48,
Angle: of refraction for the 2d image, 40° 39 —
Index of refraction for the 1st image, 1.3326 —
Index of refraction for the 2d ime 1.5134

By taking a mean of these sane Non are re extremely 1 near
to each other, we > obtain for Bh Onw rr eae R

Least refractive: power, - 1.3350 -
Greatest: refractive lec 2 it bgion’ L 5145.

Hence it follows, that. the a cattwadlain of slinehee of pot-
ash, is almost exactly ‘the: same as ‘that ‘of Water, which i is.
1,3358,—a result of such an extraordinary nature, that I felt it
mecessary to confirm it by repeated observations. ihEVs ok

In:

a sig 66°, 0.0613
Angles of the flint glass jo Dispersive powers, } es

OF NITRATE OF POTASH. 295

In measuring the dispersive power of this salt, we cannot
expect the same accuracy of result on account of the great
angle of the prism. Owing to the nebulosity of the first image’
it is impossible to measure its dispersive power; but it evi-
dently corresponds with its low power of refraction. In order
to correct the dispersion of the second refraction, it requires a
prism of flint glass, with an angle of nearly 60°. With an
angle of 66°, the dispersion is more than corrected; but with
an angle of 56° the correction is not nearly completed. The
dispersive powers due to these different angles, are contained
in the following Table:

prism, -

56 0.0546

By taking a mean between the two extreme observations,
we obtain 0.058 for the approximate dispersive power,—a result
which could scarcely have been anticipated from the substan-
ces which enter into the composition of nitre. The follow-
ing Table will shew the relation which this measure bears to
the dispersive powers of other bodies :

Sulphate of lead, - 0.060
Nitrate of potash, 2d refraction, 0.058
Flint glass, - ~ 0.048
Water, ~ - 0.035

In order to examine the character of the rays which form

the two images, I polarised the light of a candle by reflection

from glass, and viewed it through two of the parallel faces of a
hexaedral prism of nitre. When the edges or common sec-

Pp@2 tions

296 NITRATE OF POTASH.

tions of its faces were parallel to the plane of reflection; a
bright image of the candle was seen in the middle of a mass:

of nebulous light, exactly similar to what happens in the agate
when its veins are parallel to the plane of reflection. But
upon turning round the crystal of nitre, the bright image gra-

dually vanished, while the nebulous light increased ; and when:

the edges of the crystal were perpendicular to the plane of re-

flection, the bright image was extinguished, andthe nebulous.

light a maximum. When the reflected image of the candle is
viewed. through two inclined faces of the nitre, the two images

vanish alternately, like those formed by all doubly refracting:

crystals,
A prism of nitrate of potash, having its refracting surfaces
equally inclined to the axis of the hexaedral crystal, possesses
the faculty of depolarising light ; and hence it follows, from the
theory of depolari isation, that the prism must, in this case, form
two distinct images..
The two neutral.axes of this salt, are parallel ae ek
cular to the sides of the hexaedral prism ; and the depolarising
axes are parallel to the diagonals of the square base common’
to the two pynninidaiadealii compose its primitive rectangular

octaedron. The least refracted image is that which is produ-

ced by the extraordinary law of refraction. )
The beautiful coloured rings which I exhibited to the Socie-

ty, as produced’ by the action. of topaz upon polarised light, and.

which I have:also diseovered in the agate, and in a:great varie-

ty of other bodies *, exist also, but-in a very singular manner,

in the nitrate of potash.
iin o> By

-* See Phil. Trans. Lond. 1814 Part 1. p. 278.)

si

el at a Ce

whe My rg ne

— —— en

STRUCTURE OF DOUBLY REFRACTING CRYSTALS. 397

By comparing, in a rude manner, the coloured rings formed
by different bodies, with the thickness of the plates by which
they were produced, I concluded that the conjugate diameters

of the rings were nearly as ne m being the index of re-.

fraction. In the nitrate of potash, however, their magnitude is
quite anomalous, as it produces along the axis of the hexaedral
prism a series of miniature rings, nearly eight times less than
they should have been according to the preceding law. The
beautiful generalisation of the phenomena of coloured rings,
which we owe to the genius of the celebrated Bior, may per-
liaps afford an explanation of this apparent anomaly.

The Carbonate of Potash forms also two images, one of which
is bright, and the other nebulous. They are polarised in an
opposite manner, like those formed by the nitrate of potash,
but the nebulous image is more distinct in the carbonate.
With a prism bounded by natural faces, and having a refrac-
ting angle of 49° 53’, I obtained. the following measures of its
mean refractive power : ,

Index of refraction for the ebiinies image, “i 37 9°
_ Index of refraction for the bright image, _ 1. 482

VW. On THE STRUCTURE on Dovatn REneAennrE CRYSTALS...

‘Notwithstanding the numerous discoveries which have re-
cently. appeared respecting. the polarisation | of light, no at-
tempt has been made to apply them in tly the pro-
blem of double refraction. Theyfurnish us, tne” with a va-
riety of beautiful” phenomena, analogous to the polarisation of
light, which always accompanies the production of two images ;
but they afford no ground of conjecture respecting she separa-
tion of the penci into two parts.

When.

298 ON THE STRUCTURE OF

When I discovered the property possessed by the agate, of
forming a bright and a nebulous image, and of polarising them
in an opposite manner, like all doubly refracting crystals, I
was sufficiently aware of the conclusions which it authorised * ;
but as no other crystallised body exhibited analogous pheno-
mena, I contented myself with stating these conclusions as
mere conjectures, which required the sanction of numerous ex-
periments. ,

In the carbonate of barytes, however, and in the nitrate and
carbonate of potash, we are presented with properties analo-
gous to those of the agate, and are therefore enabled to resume
this subject, with that confidence which can only be derived
from multiplied observations.

When we examine the two images formed by calcareous
spar and other perfectly transparent carat we find that they
have the same magnitude, and are equally luminous and di-
stinct. There is, therefore, no circumstance which can lead us
to suppose, that the light which forms the one image passes
through a part of the crystal, having a different structure from
that which transmits the light of the other image. In the car-
bonate of barytes, however, where the transparency of the cry-
stal is imperfect, one of the images is nebulous and imperfect ;
and as the same phenomenon is exhibited in the agate and in
the imperfectly transparent crystals of the nitrate and carbonate
of potash, we are entitled to conclude, that the light which
forms the imperfect image is transmitted through the imper-
fect structure ; while the light which forms the bright image,
is transmitted through a structure of a more perfect kind.
The imperfect transparency, therefore, of the crystal, and the

nebulous

* See Phil. Trans. Lond. 1813, Part 1. p. 101.

DOUBLY REFRACTING CRYSTALS. 299

nebulous character of one of the images, can be considered in
no other relation than that of cause and effect. |
From the optical properties of the agate, this conclusion de-
rives a still higher degree of probability. The two. images
formed by this mineral are not similar to each other, like those
of calcareous spar, though they possess exactly the same pro-
perties. One of them is bright and distinct, and the other is
a mass of nebulous light. Now it happens, that the agate pos-
sesses two different kinds of structure, corresponding to the
characters of its two images, and distinctly perceptible even to
the naked eye. One of these structures is composed of small
serpentine lines, like the figures 3333, resembling the sur-
face of water ruffled by a gentle breeze; and I have a speci-
‘men in my possession, one-half of which has much larger ser-
pentine lines than the other. The light which passes through
the serpentine lines, is that which forms the nebulous image ;
while that which passes between them forms the distinct
image. This may be demonstrated by a. variety of experi~
ments. ) yah ey Pas
‘When: the light is transmitted through a part of the agate
that has the largest serpentine lines, the nebulous image has
an appearance different. from: that which it has when the light
is transmitted’ through the other part where the serpentine
lines are smaller. If the agate is. inclined in the direction of
the serpentine lines, so as not to prevent the rays from passing
between them, the bright image will be distinctly visible as be-
fore; but when the agate is inclined in a direction at right
angles to this, so as to prevent the rays from passing between
the serpentine lines, the whole of the transmitted light is ne-
bulous. Hence it follows, that the nebulous image is produ-
ced by the imperfect structure of the agate, indicated by the

serpentine

300 -ON THE STRUCTURE, OF

‘serpentine lines; while the bright image is produced by a
structure the same as that of all other transparent bodies.

The curvature of the nebulous light, in some specimens of
agate, with incurvated veins, and its constant parallelism to
the laminz, and to the direction of the serpentine lines, give
additional probability to this conclusion. 7

Here, then, we have a case of the most unequivocal kind,
in which one image of a doubly refracting crystal is produced
by one structure, or by one part of the crystal, while the other
image is produced by another structure, or another part of the
crystal ; and hence we are led to conclude, in general, that the
two images exhibited by all doubly refracting bodies, are
formed by two different structures, related to some axis or fix-
ed line in the primitive crystal. Whether this difference of
structure is produced by a difference in the arrangement. of
the elementary molecules, or is owing to a combination of dif-
ferent ingredients, is .a point which still remains to be deter-
mained. | siti '
The phenomena presented by the agate and the carbonate
of barytes, convey still farther information respecting the
structure. of these imperfect crystals. In one direction, the
light transmitted by the agate is wholly nebulous; the perfect
image being converted into a shapeless cloudy mass, and con-
founded with the nebulous image. In another direction, one
of the images is distinct and perfectly formed ; and, in one
specimen, which has the faculty of depolarisation, there must
necessarily be two perfect images. In a prism of the carbo-
nate of barytes, both the images were imperfect. In a
second prism, the one image was nebulous, and the other
distinctly formed; while, in other prisms, there was a ra-

pid approximation to two perfect images. Hence it follows,
that

DOUBLY REFRACTING CRYSTALS. 30

that the imperfect structure, which, in general, transmits only
a mass of nebulous light, allows a distinct image to be formed,
when the rays are incident in one particular direction ; while
the perfect structure, which in general gives a distinct image,
allows an imperfect image to be formed, when the light pene-
trates it by a particular path.

These inferences, which I conceive to be irresistible, have a
higher degree of importance than we may at first be disposed
to attach to them. They form a real step in the explanation
of double images, and indicate a part of that structure which
is necessary to their formation. The other phenomena of
double refraction are still involved in obscurity. '! he opposite
polarisation of the two pencils, may be explained by suppo-
sing the crystal to consist of laminze inclined in various direc-
tions ; and, as I have shewn in another place*, the same phe-
nomena may be actually produced by an artificial crystal, com-
posed of bundles of glass plates. The most perplexing point,
however, is the extraordinary refraction which takes place at a
perpendicular incidence. Whether this phenomenon is the re-
sult of an extraordinary law of refraction, as Huycens and
Newron supposed, or is produced by forces dependent on the
elementary structure of the crystal, is a question which still
remains to be determined. The extraordinary reflection and
refraction arising from the last of these causes, which I have
discovered in Mother of Pearl +, present an analogy, by no
means remote, to the phenomena of double refraction. _

* Phil. Trans. Lond. 1814, Part I. p. 280.

+ This substance, whose remarkable optical properties I have explained in
another place, resembles the Agate, the Carbonate of Barytes, and the Nitrate
and Carbonate of Potash, in giving a bright and a nebulous image, when the

Vou. VII. P. II. Qq light

302 ON THE sTRUCTURE, &c.

light is transmitted in one direction, and two bright images, when tlie light is
transmitted in another direction ; but it possesses this property under circum-
stances of such an extraordinary nature, that I could not with propriety have
introduced any account of it into this paper.

A number of soft substances, of animal and vegetable origin, have likewise.
the faculty of forming a bright and a nebulous image, under various singular
modifications. A full account of the results which I have obtained with this.
elass of substances, will be found in another paper.

XI. An Account of Observations, made by Lord Wesx Sery-
| mour and Professor PLayrair, upon some Geological Ap-
pearances in Glen Tilt, and the adjacent Country. Drawn

up by Lord Wzzp Srymour.

(Read May 16. 1814.)

bs HE river Tilt is a principal branch of the Tay, which
rises on the borders of Aberdeenshire, and runs to-
' wards the south-west, through the north-eastern part of the
county of Perth. A portion of the valley along its course, for
about ten miles above Blair of Atholl, is called Glen Tilt.
2, The adjacent country presents the common character of
the Highlands. It is mountainous and rugged, and the surface,
except in the lower parts of the valleys, is chiefly covered with
heath. Peat-moss frequently occurs. The rock beneath con-
sists entirely of those substances, which belong either to the
Primitive Formation, or the Overlying Primitive Formation, of
Werner, and of which the stratified part is by Dr Hurron
denominated Primary. This account is warranted by all the
observations which have been made upon these mountains ; R
and their general aspect furnishes a confident inference for the
whole. To the north and north-east, the mountains about the
head of the river Dee, two or three of which are little inferior
Qq 2 in

304 GEOLOGICAL APPEARANCES

in height to Ben Nevis *, are said to be mostly of granite ; and,
it is probable, that either granite, or substances akin to it, oc-
cur in many places between these mountains and Glen Tilt.
From the south-east, round by the south, to west, there is little
room to doubt that the rock is almost wholly stratified, and
that its chief components are gneiss, mica-slate, granular lime-
stone, and granular quartz, with their intermediate gradations.
This opinion was supported by our own observations, at the
Pass of Killicranky, a few miles to the south-east of Blair,
where there is a fine transverse section of the strata, and by
others upon the rocks in the channels of the Garry and the
Bruar, todhe west and north-west of Blair. Without dwelling
upon these +, I shall enter upon a detailed description of what.
appears nearer Blair, and proceed with it up Glen Tilt f.

3. In-

* Their height is about 4000 feet ; that of Cairngorm, one.of the.highest, is-
4060.

++ See Note A, at the end of the paper.

+ The minnte details, which continually occur in the following pages, must,
to most readers, appear tedious and useless. It is necessary, therefore, to men-
tion, that Glen Tilt was the first scene, in which Dr Hurron met with what he
considered as a confirmation of his views, respecting the relations that subsist

between granite and the strata adjacent to it; and, in the controversy that has. .

since prevailed, between his followers and those of Werner, the former have in-
sisted much upon the phenomena in this Glen, while the latter have repelled
their arguments by a very different account of the structure of the rocks, and of
the substances that compose them. It became of importance, therefore, to ascer-
tain the facts more precisely. With this intention, Mr Prayrair and myself.
passed some days in examining Glen Tilt, in the autumn of 1807 ; and I return.
ed again, for a short time, in 1808. In my description, I have endeavoured to
avoid the language of theory as much as possible. When any thing has been no-
ticed which is trivial, and does not immediately bear upon the main question, it

will:

%

IN GLEN TILT. 305.

8. In the immediate neighbourhood of Blair, the river
Tilt, and the small stream of the Banavie, which runs through:
the Duke of Atholl’s pleasure-grounds, afford, each of them, a
deep section of the rock, and shew that it is almost wholly
formed of strata. The slight examination which we gave to
these, led us to conclude, that they consist, for the most part,
of granular quartz, mica-slate, hornblende-slate, and granular.
limestone. An observation made with an instrument for the
purpose *, upon the strata by the side of the Tilt, not far above
its junction with the Garry, determined the stretch-to be about
N. 60° E.; and another upon the strata in the bed of the Ba-
navie gave N. 58° EK. This near coincidence must, however,
be regarded as accidental; for the position of these strata is
varied by many inflexions of their planes, especially on the
banks of the Tilt. The dip is every where southerly, at an

angle which varies considerably, but is commonly small for.
primary

will be remembered, I hope, that the occasion called for a statement of the whole
ease ; and, besides, while the mere outlines of theory.are still under discussion, it.
seems expedient, in describing phenomena which strongly affect ony single point
of importance, to enter largely into the concomitant circumstances ; since it is im-
possible to foresee what may, or may not, become subservient to a more precise:
determination of the truth.

* This instrument was a Clinometer, in its- earliest. form, without the brass:
plate. Though it was by no means so accurate as the improved one, the obser-
vations may, in general, be considered as within a few degrees of the truth.
Some error may occasionally have arisen, from the-surface of the rock being ‘ra~
ther uneven, or from its not being quite parallel to the plane of . stratification.;
For a more convenient comparison of the various positions of the strata, the
bearing of the line of stretch is} throughout, indicated by the number of degrees
east of north. As the line of dip is always at right angles to that of the stretch,
it was thought sufficient to mark on which side the depression lay, by mention-.
ing that of the four, or of the eight, principal points of the compass, which was,
nearest to its bearing.

306 GEOLOGICAL APPEARANCES

primary strata. Where observed by the side of the Tilt, it was
between 20° and 30°; in the bed of the Banavie, it was
32°.

4, On the Western bank of the Tilt, between two and three
miles above its junction with the Garry, we observed some sie-
- hite in a scar, by the side of a walk through the Duke’s plan-
tations; and in another, not far from it, some gneiss. The
soil that covered the neighbouring ground, prevented us from
ascertaining the geological relations of the sienite. The gneiss
is singular for having its component substances so disposed,
that the structure of the stone bears no marks of stratification ;
but its structure differs from that of granite, in being less per-
fectly granular, and less highly crystallised.

5. The strata in the bed of the Banavie, a little below a
bridge, that crosses it about a mile above Blair, are cut by a
vein, or dyke, of felspar-porphyry. The felspar base is chiefly
of a red colour, but partly also grey. The vein is vertical,
and about ten feet broad *.

6. There is a good road carried up Glen Tilt, as far as Fo-
rest Lodge, one of the Duke of Atholl’s hunting-boxes, nearly
seven miles from Blair. This road, after crossing two or three
small streams, in the beds of which there is mica-slate, de-
scends, about the end of the second mile, to the side of the ri-
ver. There is here a bridge, called Gilbert’s Bridge, and about
fifty yards below it, we found in the channel gneiss, interstra-
tified with granular limestone. rom the bridge the road fol-
lows the bottom of the valley, and being often carried along
the bank of the river, affords good opportunities of examining

the

* Dr Hurron mentions, (in a manuscript intended for his third volume, and
aever published) that he found several dykes, both of grey and red porphyry, in
the course of this stream.

IN GLEN TILT. 307

the rocks, which the violence of the stream has exposed’
in many parts of the channel.. The substances of which they
consisted, to a point rather more than a mile and a quarter be-
low Forest Lodge, and marked by the letter A.in the map *
(Plate XXI.), and the plan of the river (Plate XVI), were, as
far as we observed them, gneiss, mica-slate, and granular Hime-
stone.

7. On the west side of the valley, between Gilbert’s Bridge
and the opening of Glen Merk, a great quantity of fragments,
brought down by torrents from the steep bank of the moun-
tain, consisted chiefly of mica-slate ; though there were among
them a few small ones of sienite. Mica-slate may, therefore,
be inferred to be the prevailing rock on this side, and some.
strata of it, near the brow of the declivity, were distinguishable:
in the bed of a torrent, even from a distance. Strata of mica.
slate occur also at the-falls of the Merk, near its junction with.
the Tilt. Farther up, on the same side of the valley, where.
the road crosses the Criny, that stream flows over some beds of”
granular quartz.

8. On the eastern side of the valley, we often:found granular:
limestone near the road, between Gilbert’s Bridge, and ano-
ther about two miles farther up, called Gow’s Bridge; and a
quarter of a mile beyond this, limestone is visible from a dis-
tance, in a scar on the same’ side, and three or four hundred
feet above the bed of the river.

9. Through all this part of the Glen, the stretch and dip of
the strata are tolerably uniform. In four observations + made
between a point a little: below Gilbert’s Bridge, and Gow’s.

Bridge,

-*® The outline of the map is copied from Srosre’s Map of Perthshire. An ate

tempt has been made to give a better representation of the mountains near Glen

Tilt ; some names have been added, and others have been differently spelt, with
a view of conveying the Gaelic pronunciation more distinctly.

+ An observation at the falls of the Merk is included.

~

308 GEOLOGICAL APPEARANCES

Bridge, the two extremes of the stretch were N. 38° E., and
N. 51° E., and the angle of dip, which was southerly, varied
from 26° to 38°.. As far as the eye could judge, we had no
reason to suppose that the irregularity any where exceeded
these limits. |

10. Fifty yards below Gow’s Bridge, the strata, which are
here of mica-slate, are cut by a vein of greenstone-porphyry.
The imbedded crystals of felspar are few and small, and the
base is very minutely crystallised, containing, in the place of
hornblende, what seems to be common actinolite ; but this dis-
tinction is, perhaps, of little consequence, since Hauy has
been induced to unite these two substances under the same
species, on account of their agreement, both in the structure
of the crystal, and in chemical composition, as proved by the
analyses of Vauqurtin. ‘The vein is about ten feet thick, and
dips westward at a large angle.

11, At the point A, ithe corm in the bed of the river undet-
go a material change, and for upwards of three miles, they con-
sist in some places of sienite, and in others of primary strata ;
and sometimes they exhibit masses of gneiss, granular lime-
stone, granular quartz, hornblende-slate, and other materials of
primary strata, interspersed among unstratified masses of sie-
nite. An idea of the irregular succession of the stratified and
unstratified masses may a derived from the plan *, which in-
cludes the course of the river between this point and a bridge
above Forest Lodge. Appearances of the same kind occur for
a mile and a half farther up.

12. In

* This plan was laid down, by taking bearings with the compass along the
ank of the river, according to its changes of direction. and by pacing the dis-
tances. The length of a certain number of paces was determined by measure-
ment.

IN GLEN TILT. 309

T2. In some of these rocks, the sienite is seen in contact
with various materials of the primary strata, and it was our
particular object, to examine the phenomena in such cases.
But, before I enter upon a detailed account of them, it
may be of use to give a general sketch of this part of the val-
ley. |

13. Glen Tilt, for about two miles below Forest Lodge, and
for three miles above it, to the junction of the River Chlochan,
runs nearly in a straight line, in the direction of N. from
46° to 480 E., and therefore not far from N. E. and S. W.
14. The elevation of this part of the valley is considerable.
‘According to General Roy’s measurement, the lawn at
Blair is 425 feet above the level of the sea; and Mr Puay-
rarr’s observations with the barometer, indicated the dif-
ference of level between Blair and Forest Lodge to be
about 400 feet. At the time of these observations, the baro-
meter was falling, and the result is consequently too great; but
after allowing for any probable error in excess on this account,
the height of Forest Lodge above the sea can hardly be esti-
mated at less than 700 feet.

15. The bottom of the valley is narrow, rarely exceeding a
furlong in breadth, and generally much less. The lowest
banks of the mountains rise on either side with very steep
declivities; on the south-east, to the height of from 600 to
800 feet above the river; on the north-west, to between
1000 and 1200 feet. They are not cut by any lateral val-
leys ; ; except, that on the south-east side, two or three deep
ravines, descending from the sides of Ben y Gloe, join Glen
Tilt between Glen Chlochan and Forest Lodge; and on the
north-west side, a mile and a half above the Lodge, a brook,
called the Crochie *, has deeply indented the ridge of the moun-

Vou. Vi. P. I. Rr

tain,

* This stream is called in the country Auld Crochie. Auld signifies brook in
Gaelic.

310 GEOLOGICAL APPEARANCES

tain; though it has still to find its way by a succession of falls
to the bottom of Glen Tilt. ‘Towards the upper end of the
valley, the breadth of it-is contracted to that of the river, and
the declivities are lower.

16. To theysouth-east of Forest Lodge, the lowest steep of
the mountait® succeeded by a more gradual ascent to the top.
of Cairn ioorchie, which is-from 1500 to 1800 feet above
the valley. Beyond this, after a small intervening descent,
an easy ‘slope leads to the top of Cairn Kin -Callum,
one of the three broad summits of Ben-y Gloe, the ‘highest
ridge in this neighbourhood. Cairn Gowar, the most lofty
of the three, was ascertained by General Roy to be 3650 feet
above the level of the sea, and Cairn Kin Callum cannot be
much lower. The third summit is Cairn Leea, which lies at
the south-west end of the ridge.

17.-To the north-west of the Lodge, the bank that forms the
valley, is immediately overtopped by another steep, of which
the highest point is called: the Griurnon. Mr Prayram deter-
mined the-elevation of this above the valley, by means of ‘a
base measured in a flat close to the Lodge, and found it to be
1590'feet. From the Griurnon, a broad ridge extends, in a”
north-westerly direction, for nearly a'mile and a ‘half, and rises
a few hundred feet to the pointed summit of Cairn y Chlan-
nan. The height of this’ mountain above the ‘sea is probably
about 2800 feet. |

18. The opposite sides of this part’ of Glen Tilt present a
striking contrast in their surfaces. Thesouth-easternside is most-
ly covered with soil, bearing either: good herbage, or heath,'and
sshews but little of the rock, either fixedor loose. - Along’ the
north-western side, the mountain ‘has in many’places a cragey
brow, the ruins of which lie’ thickly scattered over the decli-
vity below, so as frequently to cover the-ground. This is

particularly

IN GLEN TILT. > 811

particularly the case between the Crochie, and a point) more:
than three quarters of a mile below Forest Lodge, and
opposite to M in the map, and the plan of the river.

19. Such a difference of aspect in the surface, gave reason
to expect a difference in the nature of the rock beneath. Ac-
cordingly, on the south or south-east side, we found it to con-
sist of strata, of which the chief materials were granular lime-
_ stone, granular quartz, gneiss, and mica-slate. The general.
stretch of these strata coincides nearly with the direction of:
the valley, and their dip is towards the south-east, into the face.
of the mountain, at a large angle; though the stretch and dip.
are occasionally somewhat varied by inflexions. On the north
or north-west side, the mountain is chiefly composed of grey
sienite, or rather sienitic greenstone, which bears no marks of
stratification. In the bottom of the Glen, therefore, is the line

of junction between the strata on the south-eastern side, and
the unstratified masses on the north-western; and it seems as
if the course of the Tilt had here been very much determined
by the position of the limestone strata, which occur frequently
throughout the Glen, on the left bank of the river, and have
been cut through by the stream. The facility with which
limestone is worn away by water, in comparison with most of
the other materials of a primary country, must have struck
every mineralogist, who has met with it in that situation.

20. This general account of the rocks, that form the
opposite sides of the valley, rests on the following observa-
tions.

21. We saw no sienite on the south side of the river, except
immediately on its bank. The rock, where it appears, within a
hundred feet above it, is stratified, and often of limestone. In
order to ascertain its nature higher up, we ascended the moun-
tain in two places, following, in each, a line almost at right

Rr 2 angles
ae,

312 GEOLOGICAL APPEARANCES

angles to the direction of the valley, and therefore also at right
angles to the stretch of the strata.

22. One of these lines was in the course of a brook, which.
falls down the mountain within a quarter of a mile to the east-
ward of the point A, and has made a deep section of the rock,
though not in the immediate vicinity of the river, where the
declivityis gentle. After passing over this declivity, I found
granular limestone and mica-slate, from where the rock first
appears, to the height of about two hundred feet above the ri-
ver. For the next two or three hundred feet, there followed
a gneiss, resembling that which I have already mentioned as ,
occurring near Blair, on the western side of the Tilt. It is.
rarely sersuaboasd in its texture, and its stratification can only be.
learned from the outgoings of its large beds. These, as well .
as the limestone and mica-slate below them, dip into the.
mountain to the south-east, at an angle sometimes considera-.
bly more than 45°, and sometimes a little less. To the
gneiss succeeds mica-slate, conformably stratified ; and to that,
another gneiss, a good deal similar in its texture to the last...
Its beds are crossed by numerous slaty fissures, at right angles
to their planes, which give it the delusive appearance of a stra~
‘tification dipping at-right angles to that of the rocks below;
while, in fact, the beds lie conformably. Above, are distinct
strata of granular quartz, also conformable. This quartz. was
the highest rock that I examined, and might be about six hun- .
dred feet above: the river. About a quarter of a mile farther |
to the eastward, the strata are intersected by another brook ;
and, as far as I could judge from a; distant view, they corres-
pond with those in the first, as to the lypestone, and the lower |

beds of gneiss.

23. The other line, in which the rock was examined, on this.
ade of the valley, sets off from the Tilt, at a _ bridge near half a

mile

IN GLEN TILT. 313°

mile above Forest Lodge, a spot remarkable for its distinct ex-
hibition of a junction between the strata and the sienite, in the
bed of the river. The southern bank of the river is here the foot
of a declivity, several hundred feet in height, and excessive-
ly steep, on which the rock appears only at intervals.

24. In the ascent of this declivity, Mr Prayrair saw nothing
but granular limestone, to the height of perhaps more than
three hundred feet. ‘Ihe beds of the limestone dip southerly,
into the face of the mountain. Over the limestone is a bed of |
porphyry, twelve or fifteen feet’ thick. ‘The base of the por-
phyry is a grey compact felspar, and contains numerous small
and imperfect crystals, of a reddish felspar, hornblende, and’
mica. At the foot of the declivity, and close to the bridge, there
are lying many blocks of a porphyry, which has a base of grey
compact felspar, and is singular for containing distinct crys-.
tals, not only of white felspar and quartz, but also of mica in |
thin hexagonal plates.. From the sharp angles of the ‘blocks,
they must be supposed'to have fallen from the declivity above;
but whether they are a variety of the bed just mentioned, or
from another rock, we found no opportunity to determine.

25. Above the porphyry is-mica-slate, alternating with beds:
of granular limestone ; and: Mr Prayrair observed granular
limestone upon the brow of this steep face, where it changes:
to a more gentle slope. This is the highest point that is vi-
sible from the Glen below, and, by comparing its level with
that of another on the same face, immediately above the
Lodge, the height of which was afterwards determined by tri-
gonometrical measurement, he computed it to be about eight:
hundred feet above the Tilt.

_ 26. From hence the ascent is more gentle for a considerable
distance, and the ground is covered with long heath. The:
rock is rarely seen; but what appears is mica-slate. The
Jimesin which Mr Prayram ascended, conducted him to a

ridge,

314 GEOLOGICAL, APPEARANCES

tidge, formed on one side by the-slope he had passed over,
and, on the other, by the declivity of a deep ravine, through
which flows a stream that rises in the higher part of Ben y
Gloe, and joins the Tilt about three quarters of a mile above
the bridge, by a.course almost due north, while that of the Tilt
is to the south-west. On this ridge he fond mica-slate,
stretching N. 38° E., and dipping to the south-east at an angle
of about 35°.

27. In the direction of south, and perhaps a little west,
from this spot, and at the distance of about a quarter of a mile,
is a conical eminence, of considerable height, forming the point
of Cairn Toorchie. All the way to its summit, he observed;
the rock to be a granular quartz, in which there occur thin lay-
ers of felspar and mica; and thus the stone is a gradation into
gneiss. The granular quartz lies above the mica-slate last
mentioned, and, as far as he could judge, has the same stretch
and dip. Another high and bare point, at the distance of about
half a mile on the other side of the ravine, appeared pretty
evidently to consist of a similar rock, .

28. Mr Prayrair descended towards the north, Lliaige the:
sloping edge of the ridge, by the side of the ravine, and, in
the course of his walk, went more than once to the bottom of
the ravine, in order to examine the rock. At first, he found
mica-slate upon the ridge, and, in the bottom of the ravine,
granular quartz. Lower down, there was granular limestone
upon the ridge, of the same characters with that which he had
seen in ascending the steep declivity above the bridge, and he
had no doubt that it extended all the way to the side of the
Tilt. The rock, on this part of the ridge, is indeed generally
covered with a thick coat of earth ; but, in the bottom of the
ravine, for several hundred yards before it opens upon Glen
Tilt, there is limestone, which many falls in the stream have

worn down, and scooped out, into a variety of irregular forms. |

We

x
a

IN GLEN TILT. 315

—We were prevented from examining the higher parts of Ben
y Gloe, by an unusually inclement season, which brought
showers of snow, for several days. together, before the middle
of September.

29, On the northern side of Glen Tilt, there is not much of
the fixed rock to be seen upon the lower parts of the declivi-
ties. At the foot of the lowest fall of the Crochie, and on the
west side of it, there is grey sienite, approaching to sienitic
:greenstone. In the bed of the first torrent to the east of the
-bridge above Forest Lodge, there is, on the lower. part of the
-mountain, granular quartz, stratified, and dipping.at a large
angle to the south-west, but irregular. Higher up the. same
stream, there is sienitic greenstone.

80. the rock was examined in the bed of another torrent,
which joins the lilt between the bridge and a fall-a few. hun-
dred yards below it. On ascending the course of this stream,
_the first fall in it discovers hornblende-slate, obscurely strati-
fied, but, as far as could be judged, conforming to the ordina-
-ry stretch of the strata on the south side of the valley. A
-little higher, there is sienitic greenstone, and this. continues,
-as you proceed, to a considerable distance. ‘The hornblende-
. slate seemed to lie over the sienitic greenstone. -In.a spot not
far below the Lodge, and at the height of perhaps three-or four
hundred feet above the river, the Lea is partly sienitic green-
_ stone, and partly granular quartz.

31. We examined the fixed rock of the crags:.on, the brow
-of the mountain in one or two. places only, aly opposite to
the point M, and it was there a small-grained._ sienitic green
‘stone. But very satisfactory Be rinetion: with respect to the
nature of these crags, was afforded by the angular blocks, and
loose fragments, strewed over the steep declivity below. We
~examined numbers of them through almost the whole length
of the valley, and found them to consist chiefly of eadat ans

between.

‘316 GEOLOGICAL APPEARANCES

between grey sienite and sienitic greenstone, all bearing a strong

resemblance to one another in their general character, as well —

-as to those which have been already mentioned, as occurring in

the fixed rocks on different parts of the mountain. In these

ageregates, the felspar is commonly whitish, but has various
shades of colour, and is sometimes tinged with red. The pro-
portion of the hornblende to the felspar is generally large.
The grains are in some instances large and distinct, and in
others extremely minute. Quartz is seldom an ingredient, and
mica still more rarely. I conceive the most appropriate name
for all the varieties to be Sienitic Greenstone, as the majori-
ty of them approach more nearly to that substance, than to sie-
nite. |

32. Among the angular blocks of sienitic greenstone, there
occur also a few of gneiss and granular quartz; and a little
below the point marked B in the plan of the river, I saw, on
the side of the mountain, some fragments of hornblende-
‘slate and greenstone-porphyry.

33. Along the declivity, from a point over against M, to
another a little above Forest Lodge, there are occasionally
fragments of a sienite, similar to that which appears so often
in the bed, and on the banks, of the river. This differs, in se-
veral respects, from that which approaches to sienitic greenstone.
Its chief ingredient is felspar, sometimes grey, but most com-
monly red. It also contains less hornblende, and quartz in va-
rious proportions. Nearly opposite to the point B, I found a
few fragments of it a little below the Sein one about seven
hundred feet above the Tilt.

34. To these remarks on the northern bank of the valley, it
may be added, that the Griurnon, a point several hundred feet
above the crags of sienitic greenstone, consists of granular quartz,
containing

IN GLEN TILT. 317
containing specks of felspar, or small cavities, which may be
“supposed to have been once filled by it.

35. | return now to a farther consideration of the rocks
along the bed of the river, which consist partly of strata, and
partly of sienite. Our examination of these, and indeed of the
whole Glen, was much facilitated by the kind hospitality of
the Duke of Atholl, who allowed us to fix our residence at Fo-
rest Lodge for several days.
__ 36. Among the substances that compose the strata, gneiss,
hornblende-slate, granular quartz, and granular limestone, have
already been mentioned. Mica-slate occurs more rarely. Be-
sides these, there are many compounds of quartz, felspar, mi-
ca, hornblende, actinolite, compact dolomite *, chlorite, talc,
steatite, and serpentine, which, in different rocks, are found in-
timately mixed in a great variety of combinations, and in diffe-
rent proportions. As examples of these compounds, I may
mention that, among the specimens we collected, one is a com-
pact dolomite, penetrated by chlorite and talc ; a second, horn-
blende-slaté, penetrated by carbonate of lime; a third consists
of actinolite, felspar, mica, and carbonate of lime; a fourth, of
felspar, with hornblende and carbonate of lime; a fifth, of
- guartz, compact dolomite, and brown felspar; a sixth, of
quartz, penetrated with chlorite, talc, and carbonate of lime;
aud other varieties might be added. We found steatite and
Vou. VII. P. IL. Ss serpentine

_ * By Compact Dolomite, I mean a magnesian limestone, differing from com-
mon dolomite, in having its structure compact, and such as to render the frac-
ture not granular, as in common dolomite, but splintery, and passing to the

“even. The fracture is thus well described by Mr Jameson, in his account of the

dolomite of I-columb-kill, in his Mineralogy of the Scottish Isles ; and the name

of Compact Dolomite has been used by the Comte de Bournon, in describing
some specimens from that island, in the collection of Mr Autan. Compact dolo-
mite is found also in GlenElg, and in Kintail, on the coast opposite to the island
of Skye.

318. GEOLOGICAL APPEARANCES

serpentine in one or two places only. Almost all these com-

pounds effervesce, more or less, with muriatic acid; and of

course carbonate of lime, or earbonate of magnesia, perhaps
both, are among their ingredients. Small specks of iron py-
rites are frequent in them. One of the most common of them
eonsists of quartz and compact dolomite. ‘| he quartz is in a
large proportion ; but the dolomite renders the mass extreme-
ly tough under the hammer, and imparts a little of its charae-

ters to the fracture, which sometimes approaches to that of.

eompact felspar. It effervesces with muriatic acid, though of-
ten feebly. Its colour is whitish-brown, where it is not de-
composed. By decomposition, it assumes a rusty-brown colour
near the surface, indicating perhaps that manganese is an in-
gredient. Specimens from different spots present many varie-
ties in these general characters. In some of the rocks consist--
ing of the compounds above mentioned, neither the form of a
bed, nor a stratified structure, is discernible; but we were led

to consider them as parts of the strata, from the- imperfect. ie
crystallisation of their ingredients, and their analogy to others .

that are distinctly stratified.

37. The rocks of sienite do not indicate stratification, either
by the form of a bed, or by the structure of the stone. Of the
sienite there are two varieties, one grey, and the other red ; the
colour of each depending on that of the felspar, which in both
is the principal ingredient. Both contain quartz, and agree in
most other circumstances. We paid little attention to the
grey, as we no where found it in contact with the strata ; but
the characters, which distinguish it from the grey ateavas gra-
duating into sienitic greenstone, on the northern side of the val-
ley, have already been mentioned. In the red sienite, the fel-
spar presents different shades of red, graduating into grey ; the.

hornblende varies much in its proportion, and in the size of its _

grains,

IN GLEN TILT. 819

grains ; and so likewise does the quartz *. Minute crystals of

_ Iron pyrites are sometimes interspersed ; and our specimens ef-

fervesce slightly with muriatic acid. Ata point marked C in
the plan of the river, there is a variety of sienite, or rather sie-
nitic greenstone, which I shall have occasion to describe here-
after. ys
38. In the bed of the river there are four spots, that draw
peculiar attention by affording a good exhibition of the rock,
and three of them contain the most distinct phenomena of the
junctions of the strata with the sienite. They are marked in
the plan of the river by the letters A, B, C, and D, and I shall
employ these as names in describing them.

39. The spot marked A is the first place where the siec-
nite is met with, in ascending the course of the Tilt. It
may be readily found by a singularity in the channel of the
river. Some large irregular masses cf rock project on either
side from the banks, and through thém the water has cut a
deep and narrow chasm. Above these rocks, the river holds
a course nearly coinciding with that of the valley ; on meeting
with them, it makes a sharp turn to the southward, and, after
falling a few feet, in its passage through the chasm, expands
into a pool at the outlet, and resumes its former direction.
The direction of the channel through the chasm is near-
ly N. and S$.

S's 2 40. At

* This red sienite bears a close resemblance to that of the Malvern Hills in
Worcestershire, I do not remember to have seen one like it any where else,

320 GEOLOGICAL APPEARANCES

40. At the lower end of the chasm, the rock is a large bed of
granular quartz, stretching across the river in the direction of
about N. 56 E. Its stretch is indicated in the plan* of A
(Plate XV I.) by a line expressing the water-line upon its
southerly face, and referred to by the figure 1. Its dip is to
the south-east, at an angle of about 45°. Its structure is not
stratified.

41. Immediately below this, (ati 2 in the plan) there appears
a rock consisting of quartz, penetrated by compact dolomite.
Little of it is visible on the southern bank, but what there is,
agrees in its general character with the larger masses on the
northern, and there is probably a.bed of it, conformable to that
of granular quartz.. The masses of it on the northern bank,
are intermixed with others of granular quartz, but we could
not pronounce them to be in alternating beds.

42. The rock on the north side is then concealed by the soil
for a considerable distance down the river, except that, about
forty yards below the quartz rock, (at 3 in the plan), there may
be seen in the channel some small masses of gneiss, interstra-
tified with, and graduating into, mica-slate. The ‘stretch of
these strata is N. 63° E., and. their dip to the south-east, at an
angle of about 45°. Some of the gneiss is so highly. crystalli-
sed, as to have entirely lost its stratified structure, and is here
and there in the form of veins, one or two inches in breadth,
and cutting the strata of mica-slate ata very small angle. . Fi-
gure I, in Plate XIX, is a sketch of. a, horizontal section of a
forked vein of this kind.

43. On the southern bank, the strata are much covered by
soil er a short distance below the quartz rock, but granular

limestone

* In this plan the rocks were merely sketched in by the eye. So likewise in
the plan of D..

IN GLEN TILT: 82}

limestone begins to appear about ten yards from it. Soom af-
ter, the bank of the river turns to the westward, and exhibits
the outgoings of the limestone strata for about a hundred
yards. ‘Their average stretch may be considered as about
N. 30° E., within 20° of the direction of the bank, and their
dip is to the south-east., at an angle varying from 26° to 56°.
On a close examination, some rapid inflexions may be obser-
ved, and among them, a small one is remarkable for setting the
planes of the strata at right angles to one another. This is in
the slope of the bank, near to. where the limestone is first seen
below the quartz rock.

44, Returning now to the large bed of quartz, we find next
to it, on the eastward, a rock composed of quartz and brown
felspar ; and this is succeeded by an aggregate of quartz, brown
felspar, and hornblende. The granular quartz is not bounded
on this side by any tabular face, or strata-seam ; and we had
reason to think, that the granular:quartz passes into the quartz
and felspar, and that again into the compound of quartz, fel-
spar, and hornblende. Though the constituent parts of this
last rock are those of a sienite, the mass differs from sienite in
having them less perfectly crystallised, especially the horn-
blende. It may be considered as bearing the same relation to
sienite, which the gneiss, already described as having an unstra-~
tified structure, does to granite, and perhaps may with proprie-
ty be called Sienitic Gneiss. Some specimens of it effervesce
with muriatic acid.

45. In the rock of quartz and felspar, and in that of quartz,
felspar, and hornblende, there are no marks of a stratified struc=
ture, nor are there any of a formation in beds; except that, on
the south side of the stream, the sienitic gneiss lies very dis-
tinctly over, and conformable to, some strata that follow to the
eastward of it, and dip to the south. This circumstance, as well

ay

392 GEOLOGICAL AP NEAACSERP

as the oryctognostic characters of these rocks, and the appear-
ances of gradation from the granular quartz, induce me to re-
gard them as parts of the primary strata. Yet, if they are so,
‘they have been subjected to some peculiar cause of irregulari-
ty; for the stretch of the face of the granular quartz, which
forms their western boundary, is about N. 56° E., and that of
the strata, which bound them on the eastward, is at least 80°
E. of N., while the distance between these different lines of
stretch, measured along the middle of the channel, is less than
thirty yards. .

46. The strata to the eastward are a few feet in thickness,
and consist, partly of hornbiende-slate, and partly of granular
dimestone, varying to a compact dolomite penetrated with
quartz. They appear on both sides of the river. Owing to
some disorder in them, and a good deal of inflexion in one
place, their position could not be well determined; but their
average stretch was judged to lie between 80° and 90° E. of N.,
and their dip is southerly about 40°. It must be remarked,
that these strata stretch from 17° to 27° more to the eastward
than the gneiss and mica-slate lower down, and from 50° to
60° more to the eastward than the granular limestone on the
southern bank.

47. Above this, the channel of the river opens into a broad
and straight reach for a hundred and forty yards. On either
side the bank is high, and exhibits the bare rock along its
foot.

48. Beneath the northern bank, the strata last mentioned
are succeeded by the red sienite, which may be seen on that
side with few interruptions, through the whole of the reach, and
for between forty and fifty yards beyond it. Low rocks of this
substance often project into the water.

49, On the southern bank, nothing worth notice appears for
near twenty yards, and then (at 4 in the plan) we meet with

strata

IN GLEN TILT:. . “ 323

strata lying over the red sienite, of which a large mass follows

to the eastward. The strata have somewhat of the characters of.
compact dolomite, and probably consist of this substance inti-.
mately blended with a large proportion of others. Their

stretch is about N.’7s° E., and their dip southerly at a consi-

derable angle. Near the junction there are portions of the

strata included in the sienite, so a: to produce some resem-
blance to an interstratification of the two substances.

50. From hence rocks of the sienite appear on this side also,
near the water and beneath it, through the rest of the reach,
and forty or fifty yards farther. For about sixty yards, and to
a point marked 5 in the plan, a junction of the strata and the:
sienite may be accurately traced in the bank ; ; beyond that, the
whole rock is of sienite. ‘The strata, at the junction, lie over
the sienite, dipping into the bank at an angle of from 30° to
50°. In some places they are bent. No veins of the sienite
are here seen passing into the strata, and in the body of the.
strata I observed only one small obscure vein of sienite, or aso
haps red felspar. .

$1. But i in some of the rocks. aie the northern bank, there
are junctions of strata and the sienite, attended with different
circumstances. We found there no continuous strata of
great extent, but various detached masses, consisting of granu-
lar limestone, gneiss, mica-slate, and hornblende-slate. These:
masses lie very irregularly ; some of them are imbedded in the.
sienite, and others intersected by veins of it. Two instances.
deserve to be more particularly described. |

_ 52. One occurs in some strata of mica-slate, near the Daa:
of the water, in a spot referred to by the figure 6. In. str etch
and dip, these were judged to agree nearly with the strata ly-
‘ing under the sienitic gneiss lower down ; and this makes their
hac seca to be N. from 80° to 90° E., ie their: dip southerly

about

394 . GEOLOGICAL APPEARANCES

about 40°. These strata rest on the main rock of sienite; and
from it small veins of the sienite proceed upwards into the
strata, and intersect them, running sometimes parallel, and
sometimes transverse, to their planes. I think that the veins
do not any where exceed an inch in breadth, and that they
cannot be traced for more than a foot, owing to a covering of
soil ; but, though the fact is exhibited on so small a scale, it is

very distinct.
53. The other instance is in a mass of gneiss and mica-slate,
which stands detached, at a little distance from the bank, and
close to the water, at 7 in the plan. Its form is somewhat py-
ramidal, and its greatest dimensions may be about twelve or
fourteen feet long, six or eight broad, and between four and
five high. ‘The stratification is very distinct. This mass is cut
by veins of the sienite, from half an inch to fourteen inches in
thickness, which branch in various directions, and run in some
places parallel, in others transverse, to the planes of the strata.
The veins may be traced all round the mass, and, on the south-
east side, to their connexion with the main body of sienite be-
low. Figure II, in Plate XIX, is a sketch of this rock taken
from the south-east, on the opposite bank of the river. There
is no attempt at perspective in it, and it must be understood
to represent an orthographic projection of the surface of the
rock upon an inclined plane, dipping towards the spectator ;
but care has been taken to convey a faithful idea of the rela-
tive position of the strata and the sienite, as actually exhibited
upon the surface. The strata on the west side, which rise to
the top of the rock, have their stretch N. 168° E., and their
dip westerly 51°. At the foot of the rock on the east side, the
strata dip nearly at right angles to those on the western. The
lines of junction between the strata and the sienite are marked
with great precision. Near the top of the rock, the strata that
dip to the west, where in contact with the sienite, are a gneiss
containing

IN GLEN TILT. 325

*eontaining red felspar, but this extends only a few inches, and
graduates rapidly mto mica-slate.

54. Farther to the eastward, within about twenty yards of
the end of this reach of the river, and at 8 in the plan, a cut
lately made in carrying the road along the top of the bank, dis-
plays a junction of the sienite with some strata of hornblende-
‘slate. The strata lie to the eastward of the sienite, and are vi-
‘sible for about seventeen yards. The cut into the rock is of
small depth, and, where the substances are in contact, there is.
not much to be learnt. But the strata stretch about N. 130°
E., and dip to the nor:h-east at an angle of about 60°, thus in-
dicating a position very different from that of most of the strata
already described. In these strata there are some veins of sie-
nite.

55. Beyond this, we observed nothing remarkable on either
bank of the river for a considerable distance.

56. The spot marked B lies about eight hundred yards, in 4
straight line, above A. Here we found considerable masses of
rock, consisting of gneiss, granular quartz, hornblende-slate,
granular limestone, and some of the compound substances al-
ready described, in strata variously interposed. Some of the
limestone is a fine white marble. Rocks of the red sienite al-
so appear in many parts of the bed of the river, and the face
of the southern bank affords a clear view of a body of strata ly-
ing over the sienite. |

57. To shew the irregularity that prevails among the strata
at this place, and how much their positions differ from that of
the great body of strata along the south side of the valley, I
shall mention the stretch and dip of several masses, within

Vor. VII. P. II. ae small

326 GEOLOGICAL APPEARANCES

small distances of each other. It must'be recollected, that the
ordinary stretch through the valley is between 30° and 60° E.
of N., while the dip 1 ‘is Wace to the south-east. Near the
Astute bank, a little below the face of rock in which the
strata are seen lying over the sienite, ‘are ‘some strata standing
up in the river, which: stretch N. 97° E., and are almost verti-
cal. Within twenty feet of these, tlake is, on the north side of
the stream, a large mass of strata of gneiss and ‘limestone,
which stretch N. 78° E., and ‘dip to ‘the north at.an angle of
40°. Not thirty yards edie thence, the road, which runs along
the edge of the’ nor thern batik, ‘has been cut into some strata,
composed of actinolite, felspar, mica, and a little carbonate
of lime; and these stretch N. 165° E., with an easterly dip of
24°. Within a hundred yards, on the southern bank, and far-
ther up the stream, are some strata, which stretch N. from 78°
to 83° E., and dip to the north at a large angle.

58. Where the strata in the southern bank lie over the main:
rock of sienite, we did not observe that they were cut by any
veins of sienite. But such veins abound in most of the neigh-
bouring masses of strata, of which the irregularities have been
just described, and they traverse them in every direction.
Many of the veins contain little besides red felspar, but the fel-
spar resembles that of the sienite ; and:I remarked, where the.
main rock of sienite was in contact with some strata of compact
dolomite, penetrated by other minerals, that the substance of
the rock was sometimes) merely. 7 for two or three inches
from the line of junction. rf

'59. In the pure white granular Hinaidonale ftiete are veins.
er atiie of reddish felspar, minutely mixed. with quartz.
The limestone ‘has: yielded. more readily to the action of the.
water, and left the-veins very distinctly exhibited in their pro-
jections on the-surface; but the fracture of the rock shews
the substance ‘ofthe vein to be intimately blended with

‘the

IN GLEN TILT. 327

the limestone on its sides. The outlines of these veins are
often extremely irregular, and their breadth is rapidly va-
ried. '

60. The strata on the northern bank, described above as
consisting of actinolite, felspar, mica, and carbonate of lime,
are cut by small veins, partly of red felspar, and partly of the
red sienite. ‘The outlines of these veins are very regular and
distinct. |

61. To the eastward of these strata is a greenstone porphy-
ty, similar to that of the dyke below Gow’s Bridge. I con-
ceive it to lie here in a bed conformable to the strata.

62. In many of the veins at B, shifts, or slips, are very con-
_ spicuous, and they occur even in veins of large dimensions.
_ 63. Within a hundred yards above B, the strata appear in
the bed.of the river in several places, and are much intersect-
ed by veins of sienite, or sometimes perhaps felspar.

ee

64. The spot pointed out by the letter C lies about 260
yards above Forest Lodge. There is here a fall in the river,
and large masses of rock appear on both sides of it, but they
do not afford much information to the geologist.

65. Those on the southern bank are strata, which seem to
consist either of granular quartz, or of compound quartzose
substances, similar to those at A. There is a mass of granu-
Jar quartz standing up in the middle of the stream.

66. On the northern bank, the rocks are an ageregate of red
and grey felspar, intermixed with black or greenish hornblende.
The hornblende is in a large proportion, and the stone may be
considered as one of those gradations between sienite and sie-
nitic greenstone, which have been already described. The

re? rocks

325 GEOLOGICAL APPEARANCES

rocks of this substance have not a stratified structure, nor doe
they appear to form a bed.

67. From the nature of the place, the junction of the sieni-
tic greenstone with the adjoining strata cannot easily be tra-
Seat! and the rocks of either kind present few remarkable cir-
cumstances. We found, however, some pieces of granular
quartz and gneiss imbedded: in the sienitic greenstone, and
there is an appearance of veins of sienite cutting the large mass
of granular quartz-in the middle of the river.

68. At the foot of the fall, there is a vem of granular lime-
stone approaching to compact dolomite, which cuts the rock
of sienitic greenstone for three or four feet, and varies in thick-
ness from an inch to less than half an inch. Its fracture is
splintery, but passing to the foliated. Its hardness is consider-
able; and from this, as well as from the appearance of its de-
cotapeeed surface, it is evidently penetrated by some siliceous

substance. Its colour is a dark greenish-grey ; its greenish hue.

being probably derived from chlorite. It does not graduate
into the sienitic greenstone that forms its walls, and there are
small pieces of the sienitic greenstone imbedded in it. Its ter-
mination could not be seen in either direction.

SS ee

69. The bridge over the Tilt, rather more than half a mile
above Forest Lodge, stands at the place referred. to by D.
Twenty yards above the bridge, there is a fall of the river,
and the arch is thrown between two of the nearest points of
the precipices, which extend for a short distance on both sides
of the deep pool below the fall. This is by far the most
interesting scene in the whole valley for its geological pheno-

mena. For a plan of it, see Plate XVIII.
70. On the southern bank, seventy or eighty yards below

the bridge, is the eastern extremity of a high scar, extending
from.

IN GLEN TILT. 8329

from this point for about a hundred yards down the river, and
forming at once the bank of the river and the foot of the
mountain, which rises about eight hundred feet above it, with
more than usual steepness.. The rocks, that appear in this
scar, are strata, consisting for the most part, either of mica-slate,
or, more frequently, of granular limestone penetrated with —
mica. On a close view, they were found to.be much bent:

however, their general stretch may be estimated. at about

N. 33° E., and is nearly parallel to the course of the channel at

this place. ‘Their dip is to the south-east, commonly at an

angle of from 30° to 40°, but in one place they are almost ver-

tical.

71. Over against a point fifty yards below the east end of
the scar, (at 1 in the plan) the rock begins to shew itself un-
der the northern bank. The substance of it has here a base of
grey compact dolomite, which serves as a cement to angular
pieces of quartz, sometimes so numerous as to constitute the
largest portion of the stone. The pieces vary in size, from that:
of a nut to the smallest grains. This. stone: lies ina bed
stretching about N. 48° E.; and nearly in that direction from |
hence, there is on the other side (at 1) a rock of a similar cha-
racter, near the east end of the scar, close to the water’s edge ;
so that the bed probably extends across the river *.. The dip. .
of the bed. we could not determine.

72. On the northern bank, a little farther up the stream, (at

2 in the plan) the rocks present characters that are various and
complex. From near the same spot, I have.one specimen
consisting of quartz, penetrated with talc, chlorite, and carbo
nate

* In the plan, the bearings of the corresponding substances on the southern
bank have in every instance been laid down more to the east of north, than is
stated in the description. Perhaps, in sketching the channel of the river, it was
made too broad, which would account for the error.

830 GEOLOGICAL APPEARANCES

nate of lime or magnesia, and another composed of red felspar,
hornblende, and carbonate of lime. The latter is very similar
to the red sienite ; but the substances are not so highly crystal-
lised, as is commonly the case in the sienite. Within twenty
yards, these are succeeded (at 3) by a compound of brown fel-
spar, quartz, and a small proportion of compact dolomite.
The decomposed state of these rocks, and their complex cha-
racters, make it difficult to ascertain their ingredients with
much precision. The rock last described bears some slight
marks of stratification, but the stretch indicated by them is in
a direction nearly at right angles to that of the strata on the
opposite side of the river, for it is nearly at right angles to the
course of the channel: it must be observed, however, that the
planes of these strata, if such they are, are much bent. Far-
ther up, on the southern bank, (at 3 in the plan) and in the di-
rection of between 43° and 53° E. of N. from this point, there

are rocks of substances similar in character to some of. those —

hereabouts ; and these are in distinct strata, dipping south-east,
conformably with the neighbouring strata of limestone.

73. About the place where these strata appear on the north-
ern bank, the line of the bank turns to the northward; and
from hence to the bridge, a distance of near a hundred yada
there is a straight reach of the river. On both sides of it, the
banks are high and steep, and the margin of the water is
indented by many projections of the rock.

74. In proceeding towards the bridge about twenty yards
along the foot of the northern bank, the rock is found to va-
ry considerably. It is often a mixture of compact felspar and
quartz, and sometimes a pure granular quartz, but the fel-
spar is generally the predominant substance; sometimes also
it approaches to a gneiss. Specks of pyrites occur among
these substances. Their structure is not stratified, and, if they

are

—— v

y 7
eS se ee eee he

a a a ae

a ee a

IN GLEN TILT. Jak

are in beds, the small quantity of the rock, that appears,
would hardly discover them to be so.

75. ‘These compound substances are succeeded (at 4 in the
plan) by a red sienite, very similar to that at A. Owing to
a covering of lichens, which makes every thing obscure, and a
reddish tinge, which pervades the rocks last described as well as
the sienite, the one appeared on a first view to pass into the
other; but, on a closer examination, the lines of junction be-
tween the sienite and the granular quartz, even where the lat-
ter approaches to a gneiss, were distinctly traced, and veins
of the sienite observed to run through the granular quartz.
The sienite first shews itself on the southern bank a little far-
‘ther up, (at 4 in the plan) in the direction of N. between 48°
-and 53° E. from where it first occurs.on the northern..

"6. From these points, to the fall above the bridge, a dis-
tance of about ‘sixty yards on the southern bank, and between
‘eighty and ‘ninety on the northern, the prevailing rock is the
-red sienite ; but it is interspersed, especially on the north side.
of the river, with masses of gneiss, granular limestone, horn-
-blende-slate, and granular quartz, from the size of a hazel-
‘nut, to that of several feet in every dimension. The strati-
fication of these masses is for the most part distinct. Many
of them are imbedded in the sienite; and others are inter-.
‘sected by veins of it, varying in their breadth from a small.
fraction of an inch to more than a foot.

(77. The appearances throughout these rocks are closely
-analogous; but it may be more satisfactory to give a separate
‘description of the most remarkable of them, subjoining at
the same time, that in such spots as are not particularly dwelt
upon, we observed no facts materially different from what I
have to state. Livery thing that I have to notice below the
bridge is on the north side of the river.

78. The

332 GEOLOGICAL APPEARANCES

78. Fifty yards below the bridge, measuring along the north-
ern bank, there is a large rock, (at 5) which projects farther
‘into the water than any in its neighbourhood. A little to the
‘west of this, is another rock, containing a mass of limestone
imbedded in the sienite. The junction of the two substances
takes place without any gradation, or, if there is any, it is a
very rapid one.

79. The most prominent part of the large projecting rock has
its base formed by the main body of the sienite, and its top
by several considerable masses of strata, consisting chiefly of
hornblende-slate, with some. interstratified flaps These
‘Masses appear to rest entirely on the sienite, as the sienite
can be traced below all round them. Some of them dip to
the north-east, and others at large angles to the south-west.
They are intersected by veins of the sienite, several of which
were observed to be continuous with the main body of sienite
below. One of these, which, though small, was very dis-
tinctly traced, is near the top of the rock, on the side to-
wards the bank. ‘Three others may be discovered by a close
inspection in the steep face of the rock towards the river.
The mass of strata intersected by them consists of hornblende,
felspar, and quartz, and may perhaps with propriety be called
Sienitic Gneiss. One of the veins is from six to eight inches
broad, another about four inches, and the third about an inch
and a half. The substance of the two larger veins has precise-
ly the same characters with the sienite of the continuous main
rock beneath them. Where the small vein joins the main bo-
dy of the sienite, the substance of the main body, along the
edge of the stratified mass, is chiefly felspar, and so is that of
the vein for three or four inches ; but above this, the vein is of
a sienite similar to the common sienite of the rock below.
The stratified masses separated by the larger veins exhibit no

remarkable

IN GLEN TILT, 338

gemarkable correspondence in their outlines on the opposite
sides of these veins; but there is a distinct correspondence in
those divided by the small vein.

80. Adjoining to this projecting rock, but nearer to the bank,
are several masses of gneiss. Along the lines of junction be-
tween the gneiss and the sienite, there is sometimes an appear-
ance of gradation, owing to a large proportion of felspar in the
gneiss, and an irregular structure in its stratification. We be-
lieve there are instances, in which they may be justly said to

graduate into each other, but more commonly the line of junc-
tion is pretty well defined.

81. Among the rocks immediately to the eastward, we ob-
served an imbedded mass, which, from its general aspect,
might be considered as a granular limestone, but exhibited in
some parts a singular siliceous character, especially near its junc-
tion with the sienite, though the line of junction is precise-
ly marked. This character consists in a fracture that is rather

-splintery than foliated, a hardness so considerable as to yield
with difficulty to the knife, and a greasy lustre. Yet its de-
composed surface shows that it contains carbonate of lime, and
it effervesces when pulverised. Its colour is a light greenish-
grey:

82. Not far from this, there is a vein of limestone, less than
an inch in thickness, running between two masses of sienite,
and connected with an imbedded mass of limestone. ‘The im-
bedded mass and the vein have similar oryctognostic charac-
ters. The fracture approaches more to the foliated, than that
of the substance last described, and the hardness is less. The
lustre is greasy, and the stone appears to contain a good deal
of magnesia, but not a large proportion of silex. |

83. A part of these rocks (near 6 in the plan) is formed by
some large masses of granular quartz, containing numerous

Vou. VII. P. IL » Uu specks

4

334. GEOLOGICAL APPEARANCES

specks of a reddish felspar, which give their tinge to the whole
substance. The coincidence of colour, and that want of a stra-
tified structure which is common in granular quartz, made it
easily mistaken, on a superficial view, for a gradation from the
sienite ; but a more minute examination proved the line of junc-
tion to be well defined.

84. Nearer to the bridge, and from fifteen to twenty yards:
below it, the northern bank is formed by a rock, that rises al-
most perpendicularly from the edge of the water. This rock
consists principally of the red sienite ; but, near the level of the
water, there appears in the face of it (at 7 in the plan) a mass
of granular quartz, interstratified with hornblende-slate, about
ten feet long, and four thick. The stretch of these strata is
nearly the same as that of the strata of limestone in the scar
lower down on the other side of the river, about N. 33° FE.
But their dip is at an angle of 47° to the north-west, and there-
fore in a direction opposite to that of those strata, and oppo-
site to the common dip of the strata on the south side of the
valley. They dip immediately into the face of the rock, and,
as the sienite may be traced completely round them, they are
evidently imbedded in it. These strata are traversed by two
veins, composed of quartz and red felspar, in large grains, and
not intimately mixed. The veins run almost vertically. They
are visible for some feet in the sienite beneath the strata, and
under the surface of the water, and one of them is continued
in the sienite above the strata. There is a shift in one of these
veins. | ‘
85. At the bridge the breadth of the river is much contract-
ed, and the rocks on both sides rise many feet above it, with
precipitous and irregular faces. ‘Those immediately under the
bridge, and to the east of it, are free from lichens, and their
surfaces either retain that coarse polish, which they received,

when

IN GLEN TILT. 835

when formerly cut through and rounded off by the stream, or
have had it occasionally refreshed by the action of the water in
time of floods. They are thus well prepared to show the con-
trasted colours of the red sienite, and the blackish hornblende-
slate, and to render the phenomena attending the junction of
these substances extremely distinct.

86. From the east side of the bridge, there may be seen ly-
ing under the road that leads to it from the northern bank, a
large body of granular limestone, mixed with felspar, and pe-
netrated by chlorite, and: often approaching in its characters to
aserpentine. The position of the mass, with respect to its
stratification, cannot, I think, be well determined ; but I was

inclined to consider its stretch as parallel to that of some stra-
ta, which rise, a few feet to the eastward of it, on the other
side of an intervening chasm, and the stretch of these is
N. 115° E. Veins of the sienite appear in the limestone. A
part of the main body of sienite also lies over it, and the plane
of their junction dips towards the southern bank.

87. The rock, in which the sienite thus lies over the lime-
stone from the south, terminates towards the river (at 8) ina
bold projection, affording a distinct section on its top, and on
the three sides of its perpendicular face. Its substance is a
part of the main body of the sienite, but it contains many im-
bedded masses, of various sizes, particularly about its summit.
Two of them are of granular quartz, and the lines of junction
between these and the sienite are perfectly distinct. In the
rest we observed nothing but hornblende-slate, consisting en-
tirely of pure black hornblende, except that it is here and there
interstratified with a small quantity of red felspar. The angles
of the imbedded masses are always quite sharp, even when the

mass does not exceed half an inch in its largest dimension.
In these masses there are numerous veins, of which the sub-
| Uu2 stance

356 GEOLOGICAL APPEARANCES

stance is often quite the same with that of the main body off
the sienite, but they also exhibit a variety of gradations from:
it. The crystallised grains are often larger in the veins; in
some of them there is a little mica; and sometimes, though
rarely, they contain white felspar mixed with the red. ‘There:
are small] veins of red felspar and hornblende, running parallel
to the stratification of the hornblende-slate, and veins of the
same sort occasionally traverse the strata. The lines of junc-
tion between the veins and the hornblende-slate are generally
well defined, and often extremely so ; sometimes, however, the
substances are blended. I imagine that, by a nice selection of:
small specimens, a series of gradations might be made out be-
tween the hornblende-slate and the sienite ; but in the general:
aspect of the two substances, even where: in close contact,
there is a marked distinction of character. The veins are
sometimes reticulated, and display the greatest irregularity in.
their outlines and direction. I believe that those parts of the
veins, which are near the main body of the sienite, may im
almost every instance be traced to be continuous with it.

88. The southern abutment of the bridge rests on a rock,
which projects considerably under the arch. The larger part
of it is formed of the main body of the sienite, but it contains
many masses of hornblende-slate, in which felspar is some-
times interstratified. A large one, on the east side of the rock,
contains, much felspar, and is penetrated with carbonate of
lime. Of the larger masses, some cannot be traced to rest en-
tirely upon the sienite; but others can, and some of the small-
er, which dip into the face of the rock, are manifestly imbed-
ded in the sienite. There are adjacent masses, in which a cor-
respondence of form argues that they were once connected,
The position of the masses, with regard to their stratification, —
is'very irregular; and as instances of it 1 may mention, that on

| the.

IN GLEN TILT: 337%

the top of the-rock, in an area of about ten feet by eight. there
is one having its stretch N. 143° E., and its dip south-west at.
an angle of 40°; a second having its stretch N. 36° E., and its
dip north-west at an angle of 55°; a third, which appears to
ha: e been once united to the last, stretching N. 13° E., and
dipping west at an angle of 58°; and a fourth, stretching
N. 108° E., and dipping north at an angle of 55°.. The obser-
vations were taken in an order from the west to the east side
of the rock. Of the four masses, the first and last extend to.
an unknown depth into the rock below; but the second and:
third rest entirely upon the sienite.. Veins of sienite and fel-
spar, and of gradations between them, are frequent in most of.
the larger masses, and many of them may be traced to be con-
tinuous with the main rock of -sienite below. In the small.
veins there is generally white felspar intermixed with the red. .
As in the rock last described, there are small veins of felspar
mixed with hornblende, running sometimes parallel, and some-.
times transverse, to the planes of the strata. The veins also re--
semble those in the rock at 8 in their reticulation, in the great
irregularities of their direction and outlines, and in having:
their lines of junction commonly distinct. There is here too:
the same marked difference in the general aspect of the sub-
stances of the sienite and the hornblende-slate. Sometimes
perhaps the parts in contact are blended, but this is rare..
They are usually bounded by lines that are well defined, and.
some of the imbedded pieces are remarkable for the sharp-
ness of the angles, which they exhibit in the common sec-.
tion of them and the sienite, afforded by the surface of the
roekw)

89. At the bridge, the channel-of the river makes a sharp.
turn to.the eastward. The rocks about the bridge are chiefly.

_ formed of the main body of the sienite ; but, near the fall, this is

succeeded,

338 GEOLOGICAL APPEARANCES

succeeded by a body of strata, stretching obliquely across the
stream, which is cutting its passage through them. They ex-
tend about twenty yards along the northern bank, and twenty-
five along the southern, and consist for the most part of gneiss,
hornblende-slate, and granular limestone. Some of the horn-
blende-slate on the north side of the river, is a pure ‘schistose
_ hornblende, similar to that which forms the pieces imbedded
in the rock at 8. The average stretch of these strata is about
N. 115° E., and their dip to the south-west at an angle so large
as 64°; but there are some irregularities from shifts and bend-
ings. In the strata of limestone there are many small undu-
lations, which are clearly marked on the horizontal surface, by
parallel curved ridges of interstratified hornblende and felspar :
these harder substances have been left projecting, while the
softer limestone has been worn away by the water. Fig. 11,
in Plate XX, shews the curved line of oneof these undulations on
the north side of the river. I think that the breadth from « to
y may be about a foot.

90. The strata along the northern bank are not much inter-
ected by veins of the sienite ; but those along the southern are
so in the most striking manner, especially in the neighbour-
hood of the main rock of sienite. A blast in the rock on the
southern bank procured us specimens of these veins, where
they run through some strata of a dark colour, consisting of
hornblende, intimately mixed with tale and carbonate of lime,
and shewed us that a section of this part of the rock, in any di-
rection, would exhibit a complete net-work of them. The
spot, where the blast was made, is near 9 in the plan. From
hence I traced the veins in an oblique direction towards the
bridge, irregularly branching, and again uniting, among the se-
parated masses of the strata, to their junction with the ri

bith

.
ee

IN GLEN TILT. 332.

body of the sienite, which forms the lower part of the perpen-
dicular face of rock over the river, a few yards below the fall.
In tracing the veins, an interruption, even of a few inches, in
their actual substance, was scarcely any where passed over ; and
where any interruption was passed over, it was owing to a fis-
sure, or some other circumstance in the surface of the rock, of
such a nature as to cause no doubt of a perfect continuity of

’ the substance of the vein in its original structure.. I believe -

that the various and complex ramifications of the veins, be--
tween the spot in which the blast was made, and the main bo-
dy of the sienite, would allow the: ‘connexion to be traced in
more lines than one.. As the veins approach the main body
of the sienite, they grow larger, but contain many masses of
the strata imbedded in them. Some of the imbedded masses

are of granular limestone. One of these stands nearly vertical,

©

and has its stretch about north-east ; while the stretch of ano--
ther, which is within a foot of it, and also nearly vertical, is at
right angles to this.

91. The main body of the sienite appears on the horizontal
surface of the rock for some yards to the east of the bridge ;.
and it has been already mentioned that, where the adjoining
part of the rock exhibits, on its upper surface, strata intersect-
ed by veins of the sienite, the main body of the sienite is to be
seen in the lower part of its perpendicular face over the river.
These strata, where thus intersected, appear therefore to rest
upon the main body of the sienite.

_ 92. The substance of the veins varies much in our speci-

‘mens. Sometimes it is a sienite consisting of felspar, horn-
blende, and a considerable proportion of quartz, and precisely

similar to some specimens of the main body of sienite, taken

from a rock only eight yards nearer to the bridge. This forms

the larger veins ; but some of the smaller contain only felspar
and quartz; and felspar occurs here and there alone in the
smallest.

e

.
*
840 GEOLOGICAL APPEARANCES

smallest. There is an evident gradation in these aggre-
gates.

93. In the spot where the blast was made, the veins are so
numerous, as to destroy in a great measure the character of
stratification in the rock, and in our specimens some of the
pieces cut by the veins do not exhibit a stratified structure ;
but, about six yards farther to the eastward, there are some di-
stinct, and almost undivided, strata, from which we obtained
specimens precisely similar, in their oryctognostic characters, to
many of the pieces in our specimens of the veins. Among the
pieces of strata intersected by these veins, we found also some
specimens of serpentine.

94. The lines of junction between the veins and the strata
are in general clearly defined, even in some veins of which
the breadth does not exceed the sixteenth of an inch, and the
angles of the pieces of strata are often sharp. However, there
are partial instances of gradation, by an intermixture of sub-
stances, along’ the sides of some of the veins ; and, in the small-
est of them, oe felspar of the vein pecncieantia assumes the
appearance of a streak of red spots, upon the dark ground of
the stratified mass. ‘The connexion of such streaks with the
compact veins was traced in a number of cases, without any
exception.

95. On the south side of the river, the limestone among the
more entire strata is intersected by veins of felspar, which are
sometimes interrupted, so that pieces of the felspar appear in-
sulated in the surface of the rock. Both the veins and pieces
of felspar are very irregular in their form and outlines. These
appearances of the felspar resemble those of the veins in the
limestone strata at B.

96. The strata of gneiss, on the same side, are in some places
traversed by thin veins of white calcareous spar. One of these,

about

iN GLEN TILT. 344.

about half an inch broad, at length meets a thick stratum of
grey limestone, in which, after penetrating for an inch or two,
it branches out into small tapering veins, and is lost altoge-
ther.

97. On the northern bank (at 10) a large vein of white fel-
spar crosses a part of the strata. Its thickness varies, but is
in some places between one and two feet.

98. In the veins of sienite, or its gradations, throughout the
- rocks I have been describing, shifts are not uncommon.

99. Beyond the body of strata last described, the rock on
the southern bank is lost beneath the soil for a considerable
distance, and on the northern it appears only in some small
portions of strata, in’ which we did not observe any thing of
importance.

100. It will be seen, from the plan of the river, that both
the strata and the sienite occur frequently in the intervals be-
tween the spots upon which I have dwelt so long; but there
is no other considerable section of the rock, nor are the strata:
and the’sienite often seen in contact. In every other rock, in
which we observed a junction of them, the appearances are
quite analogous to those that have been described.

101. Above the bridge also, for about a mile and a half, and

considerably beyond eu junction of the’ Crochie, the rock,
where it appears in the bed of the river, consists either of sie-
nite, or of granular quartz, gneiss, and other stratified substan-
_ces, of the same characters with those already mentioned.

The strata are occasionally intersected by veins of the red siex-
nite.

ev, Pd, oer 102. The

342 GEOLOGICAL APPEARANCES

102. The preceding details afford grounds for the following
general statement of some of the most important facts.

103. The mountain along the southern side of Glen Tilt
consists almost wholly of primary strata; that on the northern
is formed chiefly of sienitic greenstone, with gradations into
sienite. Through the bottom of the valley the rocks consist
partly of stratified substances, and partly of crystallised aggre-
gates, which are commonly sienite, but in one or two places
slenitic greenstone. (Paragraphs, 11 to 84, 66.)

104. The great body of strata on the southern side of the
valley, forming the base of Ben y Gloe, dips towards the south-
east; and some stratified rocks on the southern bank of the ri-
ver, which, from their situation and general conformity, appear
to be connected with this great body, have main rocks of
the sienite lying under them. (Parag. 49, 50, 56.) The
sienite may therefore be considered as occupying a position
‘ lower than that of these strata * *

105. The lines of junction aorta these stratified rocks and
the sienite are in most places distinct. (Parag. 49, 50, 56,
58.)

106. The strata, which occur, with scarcely any visible inter-
ruption, through the lower part of the Glen towards Blair,

and

* Jt must be observed, that the fact of the sienite lying under these primary,
or primitive, strata, is inconsistent with the geognosy of Werner, who assigns
to sienite a place in his Overlying Primitive Formation, that is, in a class of stra-
ta, which, according to him, always rest on the primitive strata, when those of
the two classes are found in contact.

IN GLEN TILT: 343

along the slope of the mountain on the south side of the val-
ley, preserve a considerable degree of uniformity in their
stretch and dip, and vary their position slowly by large undu-
lations ; on the other hand, some stratified rocks on the south-
ern bank of the river, which appear to be connected wiih this
great body of strata, but are adjacent to the main rocks of sie-
nite, exhibit great varieties of position within a small distance,
and rapid changes in the curvature of their planes. (Pa-
rag. 9, and from 19 to te compared with 43, 45, 46, 50,
70, 89.)

107. Adjacent to some spots, where the main rocks of sie-
nite, and the great body of strata, appear either in contact, or
~near to each other, there are numerous masses composed of
substances which are stratified, and closely resemble those that
form the great body. These masses do not touch each other
at the present surface, and sections of the rocks in every direc-
tion: prove that many of them must be completely separate.
The smallest of these masses are not larger than a hazel-nut ;
the larger would measure several feet every way. From the
numerous sections of these masses, afforded ‘by the indented
and water-worn surfaces of the rocks, we farther learn, that the
concealed surfaces of the masses are rough; that their shapes
are irregular, and that they often terminate in sharp angles.
In position, as to stretch and dip, they often differ extremely
from the great body of strata, as well as from each other; and
this difference prevails even among such as lie nearest toge-
ther. (Parag. from 51 to 53, 76, from 78 to 81, 84, 87, 88,

108. Some of these masses rest upon he main rocks of sie-
nite. _ (Parag. 52, 53,79, 87, 88, 91.)

109. The intervals between such of these masses as appear
adjacent on the present surface, vary in breadth, from the small

Xx 2 fraction

B44 GEOLOGICAL APPEARANCES

fraction of an inch, to many feet. The intervals exhibi¢
great diversity and irregularity in their forms; but an ap-
proach to parallelism between the surfaces of the masses,
that lie nearest together, often gives to the interval the form
of a vein. In all the various sections of the rock formed by
the present surface, the intervals, whether above, below, or on
the sides of the masses, appear, with few exceptions, to be
completely filled, either with a sienite similar to that of the
main rocks, or with felspar, either pure, or mixed with other
substances, so as to present evident gradations from that sie-
nite. (Parag. from 51 to 54, from 58 to 60, 76, from 78 to 81,
84, 87, 88, 90, 92.)

110. This appearance of separate masses of strata, with the
intervals filled with sienite, was observed only where the great
body of strata, and the main rocks of sienite, were each of
them at no great distance. (Parag. 3, 6, '7, 21, 22, from 24 to
28.) One or two exceptions, however, occurred farther up the
Glen *. 4

111. In several instances, the sienite and its gradations,
which appear, in the form of veins, among the stratified masses
resting upon the main rocks of sienite, were observed to join
to the main rocks of sienite, without any abrupt change of cha-
racter between the substance of the vein, and that of the main
rock below. (Parag. 52, 53, 79, 87, 88, 90.)

112. The lines of junction between the stratified masses, and
the sienite, or its gradations, are in most cases definitely mark-
ed. (Parag. 50, 53, 59, 60, 75, from 78 to 81, 83, 87,88,

90,

* See the latter part of parag. 135, and note D at the end of the paper.

IN GLEN TILT. 345

90, 94.) The principal exceptions are, where the strata are of
gneiss, or of granular limestone *.

118. Shifts occur in the veins of sienite, and its gradations.
(Parag. 62, 84, 98.)

) ae :

114. These appearances afford grounds for some inferences

respecting what took place in the formation of these rocks.
115. A crystalline character in a rock is generally admitted
to prove, that it was once in a state to a certain degree fluid.
An opposite notion has indeed been advanced by Dotomigv,
and Mr. Grecory Watt; but, both the mineralogical appear-
ances, which suggested this opinion to Dotomigv, and the ex-
perimental. results, which led Mr. Warr to it, admit of an
easy explanation, from what Sir James Hawi ascertained by
experiment, with regard to the varieties of structure produced
by cooling under different circumstances; and no sound ar-
gument against the common opinion can be drawn from
what either of them has described. We may therefore in-
fer, that the main rocks of sienite have been in a state
to a certain degree fluid; whether by aqueous solution,
or igneous fusion, I do not now consider. We may make
a similar inference for the sienite, and the gradations from
it, which now occupy the intervals between the separate
masses of the strata, often assuming the form of veins.
I would farther infer, that the fluid from which the main
rocks of sienite crystallised, and the fluid from which the
veins of sienite, or its gradations, crystallised, were one and the
same ;

* The least real gradation may in appearance be a considerable one, where
the surface of the rock cuts the plane of the junction at a small angle. This is a
source of deception to be guarded against in observation.

346 GEOLOGICAL APPEARANCES

same; and that so far the main rocks and the veins are of
the same formation, or have a common origin. This infer-
ence will probably be disputed by some, and I shall therefore
offer a few remarks in support of it.

116. All would admit, that every part of one of the main
rocks of sienite in the bed of the Tilt was of the same forma-
tion. As in any other case of a rock of a crystallised aggre-
gate, such as granite, greenstone, &c. the continuity of the
mass, and its uniform, or gently varied, characters, are the
grounds for the inference. It is the most simple hypothesis,
and the rule that “ No more causes are to be admitted than
“‘ are sufficient to account for the phenomena,” authorises us
to conclude in favour of one productive process, where no rea-
sons can be shown for inferring more than one. We have
seen, however, that among the veins there are some con-
sisting of a sienite precisely similar in its characters to that
of the main rocks; and that some such veins are con-
nected with the main rocks, without any abrupt transition.
Now, where both these circumstances occur in the vein, ‘the
vein and the main rock are parts of one continuous and ho-
mogeneous mass ; and every reason for admitting that any two
parts of the main rock are of one formation, goes equally to
prove that the main rock and the vem are of one formation,
except in what regards the difference of form in the vein.
But this difference affords no just ground of distinction. In
several places, especially about the bridge, there are separate
masses of the strata imbedded in the sienite. When ‘such
masses lie far asunder, the sienite between them is regarded as
a part of the main rock: if we leok out for such as have still
smaller and smaller intervals between them, we shall by and
by find the intervening sienite to obtain the form, and the
name of a vein; and the sooner, according as we select larger

bie masses

IN GLEN TILT. 347

masses of the strata, and such as have their adjacent sides more
nearly parallel. The gradation thus pointed out removes
any objection from the extreme case of difference in the form
of the vein, where the vein is in substance precisely similar to
the main rock, and visibly continuous without any abrupt tran-
sition. .

117. In the next place, we have the evidence of close analo-
gy, for extending the inference of a common origin to those
veins in the neighbourhood of the main rocks, which consist of
a sienite similar to that of the main rocks, but between which
and the main rocks no connection can be traced on the pre-
sent surface. These veins are in substance similar to the for-
mer, and they intersect similar strata in a similar manner. Their
proximity to the main rocks therefore argues that they either
are, or have been, connected with the main rocks, though that
connection does not now appear.

118. With respect to all the veins which consist of a sienite
similar to that in the main rocks, an argument may be derived
from stating the question in a dilemma, between a common
origin and a different one ; and the probability of the former
must be proportionate to the improbability of the latter. Now
a sienite of these precise characters is by no means common,
either among minerals in general, or among those of the adja-
cent district ; and it must appear highly improbable, that two
separate processes should have agreed in producing it, with
such perfect similarity of substance, in these contiguous spots,
and there only.

119. Among the hypotheses, by which a separate formation
has been ascribed to veins analogous in character, and situa-
tion, to those in Glen Tilt, is that of a cotemporaneous forma-
tion by secretion from the strata, while yet in a soft state.
Should this hypothesis be applied to those veins of sienite in
Glen Tilt, which are of a substance precisely similar to that of

the

348 GEOLOGICAL APPEARANCES

the main rocks, it may! be opposed with peculiar force by the
last argument. The formation of the main rocks of sienite:
cannot be explained by secretion ; and the improbability that
two. separate, processes should have agreed in producing im
contiguous spots a substance so rare elsewhere, as this sienite,
is materially increased, when those two processes are supposed:
to have differed in. kind. .

120.. From the veins, which consist of a sienite similar to
that of the main rocks, it is easy to extend the argument to al-
most all those veins, which consist of various aggregates of fel-
spar and quartz, or felspar and hornblende, with a little mica.
in one or two places, and those whieh contain felspar only.
These present a great diversity in their ingredients, and in the
size of the grains; but their continuity with the veins.of sie-
nite, and the gradation of the substances composing them into:
the sienite, were traced in many instances, even where the
veins were most minute and obscure, and their ramifications
most complex. These circumstances. furnish sufficient grounds
for referring their origin to the same fluid mass. Above the
bridge, where the specimens were procured by a blast, we
found many of the most minute and complex veins of this
kind to graduate into veins of sienite, which again were joined
to the main rock of sienite, and grew larger as they approach-
ed it; while we observed that in a stratified rock, of precisely
similar characters, a little farther to the eastward, there were
no such veins, or scarcely any. (Parag. 90, 93.) This,
while it seems to exclude every explanation of those veins
from. circumstances, attending the formation of the strata,
points strongly. to the once fluid substance of the main rock of
sienite for their undoubted. origin *.,

: ) | 121, We

»* Sée note, B at the end: of the paper.

eS

IN GLEN TILT. - B49

121. We may likewise recur to the argument, that veins of
these substances appear rarely in the strata of the adjacent
country, where no main rock of a crystallised aggregate is
near.

122. It may farther be remarked, that the substance of the
main rocks of sienite is not quite uniform in its characters, for
in them the proportion of hornblende and quartz varies a
good deal, and is in some places small. A main rock at B was
mentioned, (parag. 58.) which, where in contact with strata of
compact dolomite with other ingredients, consists sometimes of
felspar only, for two or three inches from the line of junction.
A similar fact occurs at D. (Parag. 79.) While, however, we
admit, that the substances thus graduating into one another
were formed by crystallisation from the same fluid, the simi-
larity in the other circumstances of these veins forces us to
conclude, that some very trifling difference of cause was suffi-
cient to determine, whether hornblende and quartz should en-
ter ito the composition of the vein, and in what proportions.

123. It must at the same time be allowed, that there are cer-.
tain veins of similar substancés among these strata, of which it
may be doubted if they have been formed from the same fluid
mass with the main rocks of sienite; such especially are the
large vein of white felspar on the east side of the bridge, and
the veins of red felspar with quartz, intersecting a rock of sie-
nite, and an imbedded mass of strata, at the foot of the north-
ern bank, below the bridge.

124, The similarity of the stratified substances, lying in se-
parate masses among the sienite, to those which compose the
. base of Ben y Gloe, and occupy a wide district to the south
and west, leaves no room for doubting that both are of the
same formation. But if this be admitted, and likewise the
common origin of the sienite in the main rocks, and in the

Vox. VIL. P. I. Yy

veins,

350- GEOLOGICAL APPEARANCES

veins, the intermixture of the stratified masses with the sienite
remains to be accounted for, and the case seems to admit of
only two hypotheses. One is, That after the sienite had assu-
med its present form, the stratified substances were deposited
in the cavities of its surface. But the forms of these supposed
cavities,—the absence of crystals on their sides, as now exhibited
in the lines of junction,—the structure also of the veins, divid-
ing upon the sharp angles of the interjacent masses, branching
with every. variety of size and direction, and crossing each
other among the stratified masses,—all these circumstances
make it difficult to imagine, that the sienite would have receiy-
ed its present appearance, if at perfect liberty to assume that
which crystallisation tended to give; and the diversities in
position among the stratified masses, relatively both to the sie-
nite and to one another, furnish the strongest objections to the
idea that these positions were original.. This hypothesis there-
fore, though it has been adopted by some to explain analogous
appearances elsewhere, may be rejected without hesitation.
The hypothesis which remains, is, That the masses of gneiss,
limestone, &c. are portions of strata once continuous, and ly-
ing conformably with those which form the base of Ben y Gloe;
that these strata were: bent and broken by some violent shock;
and that the fluid, from which the sienite crystallised, was in-
troduced among the fragments.

125. Admitting this as the most probable, the nature of that
fluid comes immediately into question. It may be supposed to
have been some unknown aqueous fluid, which held the substance
of the sienite in solution, and deposited it by crystallisation. |
To account for the various positions of the fragments, and the
height at which they are now found resting upon the main
rocks of sienite, it may be supposed, that tiie. fragments fell at

various times from the sides of a chasm, in which the deposi-
tion.

IN GLEN TIL’. 351]

tion of the sienite was going on. But an objection to any
idea of a crystalline deposition from. an aqueous fluid, arises
from the compactness of the rocks consisting of stratified mas-
ses intersected by the sienite. ‘This circumstance has been ur-
ged by Mr Puayrarr, as an objection to the aqueous origin of
granite rocks * ; and the argument may be applied with greater
force to the veins of sienite in Glen Tilt. Had an aqueous
solvent deposited this substance among fragments, in some
places so confusedly heaped, in others so closely fitted, toge-
ther, we might have expected to have found occasionally what -
so frequently occurs in a calc-tuf, a porous structure, and ca-
vities, perhaps lined with crystals. On the contrary, in all
these veins, however complex and minute, scarcely a single in-
terstice appears unfilled.

126. It is to heat then that we may with more probability
ascribe the fluidity of the sienite. This hypothesis is farther
supported by the affinity of sienite to trap, or whinstone ; and,
in proportion to that affinity, we may extend to sienite the in-
ference of an igneous origin, which, with respect to trap, seems
established by so many convincing arguments. The crystallis-
ed aggregates of Glen Tilt afford excellent examples of
gradations between these substances, and the first steps of
the series from trap may be traced in the sienitic green-
stones of the northern side of the valley; some of which
very nearly resemble the most highly crystallised specimens
of common greenstone from Salisbury Craigs. The sie-
nite in the bed of the river may be considered again as a step
in a continuation of the series to granite ¢. But, though these ©

Yy2 gradations

* See Huttonian Theory, art. 81.

+ This series of gradations, in composition as well as structure, between
trap and granite, does not appear to have been duly noticed ; and I would parti-
ularly recommend it to the attention of those geologists, who, while they admit

the

352 GEOLOGICAL APPEARANCES

gradations afford a presumption in favour of the igneous origin
of all granitic substances, that presumption must always dimi-
nish, as the affinity of the substance grows-more remote; and
we have yet to wait for proofs, as strong as those which the
valuable experiments of Sir Jamzs Haz have furnished for
trap, to be drawn from direct experiments, in the same way,
upon sienite and granite.
127. Even admitting the sienite to have been introduced in
a state of fluidity from heat, it is still difficult to account for its
having completely filled up every interstice among the frag-
ments; and it seems necessary to infer, that it flowed with a
strong impulse, while at the same time a pressure of superin-
cumbent matter, confining the adjacent bodies, opposed its in-
troduction. Indeed, if the sienite be inferred to have been
fluid from heat, compression must be admitted to have modi-
fied the action of that heat, since the carbonate of lime in the
sienite appears to have suffered no decomposition. If we
ascribe the fracture of the strata, the disorder in which the
fragments now lie among the sienite, and the wide separation
of some of them, to the force of the impelled fluid, we shall
adopt a simple, and connected, explanation of the phenomena.
In favour of this it may be further urged, that the fracture
and dislocation of the strata are confined to the r eighbourhood.
of the sienite, while those at a distance are ie un-
disturbed.
128. Even close to the junctions, the large masses of strata
en the southern bank, similar in their component substances
| si to:

the igneous origin of trap, cannot bear the idea of violating by any such hypo-
thesis the dignity of a rock, which has been so long venerated as the first founda-
tion of the earth. The specimens, required to exhibit the whole series, would
not be numerous, though the shades of difference, in every step, were slight.
Perhaps our island does not afford a better field for illustrating the subject that
- Tilt, and the mountains to the north-west of it.

IN GLEN TILT. 353

to those among the sienite, but more nearly conforming in
their position to that of the stratified base of Ben y Gloe, do
not contain veins of sienite, or its gradations; (parag. 40, 43,
50, 56, 70.) and this fact, while it goes to exclude the idea of
secretion, or any other tranquil process, attending the forma-
tion of the strata, as the source of the veins, argues that the
force, which disturbed the strata, was one which impelled the
fluid against, and among, them.

129. Some of the main rocks of sienite were observed to lie
underneath large masses of strata, which are comparatively un-
disturbed, exhibit no veins of sienite, and are probably con-
nected with the great body to the south. This circumstance
favours the inference, that the direction of the impelled fluid
was either lateral, or from below.—That the direction of the
impulse was in some degree from below, may be inferred from
another circumstance. On the top of some of the rocks of
sienite, near the bridge, there are imbedded masses: of horn-
blende-slate:; Among these rocks, that referred’ to in the
plan by the figure 8 is one which exhibits such masses with
‘peculiar distinctness ; and, in its perpendicular face, the sienite
of the main rock is seen to the depth of several feet below
them. The sienite of this rock was found to have its specific
‘gravity 2.67; and of two masses of hornblende-slate resting
upon it, one has the specific gravity of 3.00, the other that of
3.01. Hence it appears, that the specific gravity of the horn-
blende-slate is to that of the sienite, as 100 to 89. Now the
specific gravity of the sienite, when fluid, whatever may have
been the cause of its fluidity, was probably less than it is at
present, and supposing it to have been somewhat greater, it
must have been considerably less than that of the hornblende-
slate : it can hardly therefore be imagined, that, if the fluid
sienite came from above among the fragments, it would have

buoyed

Bot GEOLOGICAL APPEARANCES

‘buoyed them up, and raised them to their actual position *.
Nor can'this be explained even by supposing, that these mas-
ses of hornblende-slate were attached to others of gneiss, and
limestone; for, while the heaviest specimen of sienite has the
specific gravity of 2.67, the lightest of two specimens of gneiss
was found to have that of 2.68, and the lightest of three speci-
mens of limestone that of 2.70. A fluid impelled from below,
though of a less specific gravity, might raise them; and that
they should have remained suspended till the sienite crystallis-
ed round them, may be accounted for by the supposition, that
the sienite was in that state of viscid fluidity, which earthy
bodies, when melted, are known to assume at a temperature
not far above their point of crystallisation ; joined to the consi-
eration, that the difference of specific gravity could not be
great.

130. Any theory ascribing the origin of the sienite to an in-
troduced fluid, of whatsoever kind, would lead us to account
for the gradations, which in some places appear upon the lines
of junction, by supposing that the stratified masses were acted
upon by the fluid, so as to admit of their being penetrated by
it, or at least by some of its ingredients. After having ascrib-
ed the fluidity of the sienite to heat, it is obvious to refer the
mutual action of the substances to the same agent, and to sup-
pose that it softened the strata, so as to enable certain ingredi-
ents of the fluid to penetrate them to a small depth. Some
instances of gradation, where carbonate of lime is one of the

substances,

_ *® The large projecting rock below the bridge furnishes a similar argument.
The specific gravity of one specimen of hornblende-slate, from the top of this
rock, was found to be 2.95, that of another 2.97: the specific gravity of its sie.

‘nite was not tried, but the mean onl gravity of two specimens of sienite
from D is 2.66.

IN GLEN TILT. 355

substances, agree very well with an igneous theory. Sir James
Hau found carbonate of lime, when fused under compression,
to be a powerful solvent of silex. This offers an explana-
tion of the gradation on the sides of the veins of felspar
in the strata of limestone at B, and of some similar ap-
pearances at D, (parag. 95.) ; also of the siliceous character in
the mass of limestone adjacent to the sienite at D, below. the
bridge, (Parag. 81.). In these cases, it may be supposed that
the carbonate of lime, when fused by heat, derived a portion
of silex from the felspar in contact. ‘The siliceous character of
_ the vein of granular limestone, or compact dolomite, at C, may
be accounted for in the same manner. On the other hand, it
may be supposed.that the sienite of the main rocks derived
its small portion of carbonate of lime by solution from the ad-
jacent strata. But;-whether we adopt an. igneous theory, or
any other, there are facts that it will appear difficult to ex-
plain ; for we have seen that there are masses of hornblende-
slate, and other substances, which, though penetrated by the
felspar of the sienite, have still preserved a stratified texture,
and the sharpness of their angles; and it is not easy to con-
ceive a state of aggregation soft, or porous, enough for the for-
mer circumstance, and at the same time firm enough for the
latter, or what agent could have produced it *. I have heard
“een Six.

* A remarkable example of fragments of a rock penetrated by an extraneous
substance is mentioned by M. Davsutsson, as having fallen under his own obser-
vation. In a note to § 72. of his translation of Werner’s Theory of Veins, he
tells us, that near Freyberg a metalliferous vein was found divided into several
small veins, containing between them fragments of gneiss, th rough which gale.’

_ na was disseminated in so large a quantity, that the quintal of gireiss contained!
thirty pounds of lead» He adds, as something more remarkable, that it was.
only the gneiss of the vein, which contained galena; for the gneiss of the rock, .
even where adjacent to the vein, contained none at all. :

356 GEOLOGICAL APPEARANCES

Sir James Harr mention the aggregation of curd and jelly, as
an analogy to obviate similar difficulties. Perhaps the pene-
tration of a fragment still retaining its shape may in some
cases have been effected, by one more soluble component
having been withdrawn by the action of a fluid in contact, and ~
having thus left the pores it occupied to be filled with a new
substance, derived from the fluid. It is clear, however, that
where there is gradation on the lines of junction, it has been
owing in some cases to a trifling difference of circumstance ;
for, among the specimens procured by a blast at D, the lines of
junction are precisely marked in some, while in others the red
felspar appears disseminated through the same blackish strati-
fied compound for an inch, or more, from the side of the
vein.

131. An igneous theory for the sienite might lead us also to
ascribe the high state of crystallisation, in some of the stratifi-
ed masses, to a slow reconsolidation after having been soften-
ed by the heat. Sir James Hatu’s experiments upon. the fu-
sion of carbonate of lime under compression, make it more
easy to admit this hypothesis with respect to the limestone,
than in the case of the gneiss, and some other substances.
The important information respecting the properties of carbo-
nate of lime, which we have derived from Sir James Hatu’s
experiments, may assist us in explaining some other appear-
ances in these rocks. Thus we may conceive that the vein of
limestone proceeding from an imbedded mass, (par. 82.) was
produced from a part of the mass which had been completely
melted, and remained so, after the sienite had grown so hard
as to admit of a crevice being formed. A similar origin may
be ascribed to the vein of hard granular limestone at C,
(par. 60.). The veins of calcareous spar, cutting strata of

gneiss, (par. 96.) may have been formed, either from fused por-
tions

IN GLEN TILT. 35%

tions of the adjacent limestone, introduced into crevices in the
gneiss, or by secretion from the strata themselves, in which
carbonate of lime is frequently an ingredient, and limestone
an interstratified substance. Sir James Hau observed that
carbonate of lime, when fused under compression, is a viscid
substance. In some limestone strata not far from the sienite,
on the eastern side of the bridge, (par. 89.) there are rapid in-
curvations, without fracture, which strongly suggest the idea
of a viscid state in the rock, at the time of their formation.
132. It has been mentioned, that there are shifts in some of
the veins *. Whatever theory be adopted respecting the man-
ner in which the sienite, and the stratified masses, assumed
their present relative position ; the shifts prove that, after they
had done so, there was a dislocation among these rocks, in
which the stratified masses, and the sienite between them, were
moved together. But the fact that these rocks are now com-
pact, and without cavities, can hardly be reconciled with the
idea of such dislocation ; unless by admitting that, when it took
place, a certain degree of softness pervaded their whole sub-
stance, both the strata, and the sienite. It accords with an ig-
neous theory to explain these cir¢umstances by supposing, that
the dislocation occurred not long after the introduction of the
sienite, while the heat continued sufficient to maintain a sofiness
through the whole. But the difficulty of conceiving such a soft-
VoL. VIL. F. iE Zz, Z ness

* In a rock near the bridge, there was noticed (par. 84.) a shift in one
ef two veins, which are apparently of posterior formation to the sienite. It may
_ be worth while to observe, that these veins dividing both the sienite, and
the imbedded mass of strata, can hardly be ascribed to secretion ; for it is highly
improbable, that the strata, which are of granular quartz and hornblende-slate,
should have agreed with the sienite in secreting the same substance; nor is it
likely, that a secretion from the one, should have filled that part of the crevice,
which had been formed in the other.

358 GEOLOGICAL APPEARANCES:

ness in all these substances recurs upon us; and the advocates
of an igneous theory cannot pretend to furnish a satisfactory
explanation of these, as. well as many other more common
phenomena of a primary country, till they have acquired a far-
ther knowledge of the properties of bodies composed of fet
spar, quartz, hornblende, carbonate of lime, mica, &c. when”
subjected to high temperatures, and regulated cooling o,—with
compression also, where there is any volatile ingredient. It is
to an igneous theory, however, that we may look with the
most confident hope, and it seems in vain to expect as-
sistance from any hypothesis of aqueous solution and depo-
sitions
133. The various inferences, for which I have been contend-
ing, have been separately considered, both for the sake of keep-
ing the argument distinct, and because I conceive the evidence
to be much stronger in favour of some, than of others. The.
whole hypothesis may be briefly expressed thus: That the sie~
nite, in a state of igneous fusion, was impelled from below, by
a violent force, against the strata; that it bent them, broke
_ them, dispersed them, and filled up the intervals, which it now
occupies ; that the fragments of the strata were in some degree:
softened by the hadi sienite, so as to admit of a sareslail ac-
‘tion; that, while the whole intermixed ma S was still soft,
some farther dislocation took place in it, and that all this oc-
curred under a great confining pressure of incumbent matter.
This hypothesis ee icides,3 in the main, with that by which Dr
Hurron explained the phenomena in Glen Tilt, in a paper
read before this Society in the year 1790, and published in its _
Transactions. If it differs widely from the speculative views
concerning these phenomena, which have been more recently
given by Professor Jameson and Dr Macxnicut a must leave
it to the candid inquirer to decide between us ; | if I have

differed:

IN GLEN TILT. 259

differed also in my description of the facts, Professor Jamrson’s
extensive experience, and acuteness in the discrimination of
minerals, might seem to claim submission on my part; did I
not consider me his observations must have been liable to a
certain degree of bias from a favourite theory,—a bias, from
which I can scarcely flatter myself that my own were kept en-
' tirely free *.

134. I proceed now to describe the rocks in the bed of the
Tilt, as far as the junction of the Tarff, and shall subjoin some
observations on the mountains to the north-west of the
Glen.

185. For about a mile below the junction of the Chlochan,
the channel of the Tilt is perfectly straight, and the bottom of
the Glen is contracted to its breadth. The channel is here
formed on both sides by rocks of a singular aggregate, ap-
proaching in its characters to sienitic greenstone. ‘The colour
of the mass is a dark greenish-grey, but varying according to
the proportion of its ingredients, which are intimately mixed,
and seem to be. apne felspar, sometimes commpact, and
carbondts of Aime; or eer perhaps both. The presence
of these last ingredients is inferred from its effervescing brisk-
ly with muriatic acid. It may not be improper to consider
the mass as a compound of hornblende, felspar, and compact
dolomite, with a little chlorite, or steatite. Its hardness is not
great, but it is very tough under the hammer. It is neither
Zz 2 | stratified,

* See note C.

360 GEOLOGICAL APPEARANCES

stratified, nor in beds. Sometimes it presents an appearance
of veins, a few inches in breadth, and consisting of a brown-
ish-red compact felspar, hornblende in large distinct grains,
with a curved foliated fracture, and a little quartz. These
veins, if they deserve that name, differ from those of the red
sienite already described, in the irregularity of their outlines,
and in a slow gradation on their sides into the contiguous, mass.
In the bed of the Tilt, not far from where it receives the
Crochie, there is a rock of a similar character as to its consti-
tuents, which is in some places cut by veins of the red sienite,
and the lines of junction are there precisely marked.

136. On the east side of the foot of the fall of the Crochie,
and nearly on a level with the grey sienite, or sienitic greenstone
on the opposite bank, (par. 29.) the rock is of a character similar
.to that last described, though its structure approaches to slatys
It effervesces slightly with muriatic acid, and seems. to be a
compact dolomite, penetrated by tale and chlorite. It is pro-
bable that a great part of the base of the mountain, between the
Crochie and the head of the Glen, consists of similar agere-
gates ; for a cut made by a brook farther up, shewed the rocks,
to the height of two, or three hundred feet, to have a strong re-
semblance to those that form the channel of the Tilt*. I
consider all these congenerous. rocks. as belonging to the pri-
mary strata. In their constituents they resemble some of the
compounds that I enumerated in the general sketch of the stra-
ta through the valley ; and one of them, which has been men-
tioned as. occurring in, the bed of the Tilt, not far from the

junction:

* Some of these substances bear a considerable resemblance to those which.
appear on the Malvern Hills, in the cut made by the road to Ledbury. The
latter are in a state of decomposition, which makes it difficult to discern their in:

=

gredients. he

IN GLEN TILT. 361

junction of the Crochie, and as cut by veins of the red slenite,

has in some parts a stratified structure. Their imperfect cry-

stallisation, the smal! proportion of the felspar, and their

brisker effervescence with acids, are the characters which dis-

tinguish them from the sienitic greenstones, that form so con-

siderable a part of the northern bank of the valley. Along

the foot of this bank, between the Crochie and the junction of
the Clochan, angular blocks of sienitic greenstone, with similar

varieties, still occur at intervals in great numbers, and shew

that the higher parts of the ridge contain a large quantity of.
this substance.

137. On the south side of the long straight reach of the ri-.
ver, granular limestone appears in two or three places. Near
the lower end, there are some beds of it extending about sixty:
yards close upon the edge of the water, in a face of rock that
is nearly vertical, and a few feet in height. The lines, that
mark the stratification of the beds, run horizontally in the face
of the rock; but.at each end the beds are curved upwards in a
remarkable manner, so that at the eastern, the lines of stratifi-
cation make an angle of between 30° and 40° with the hori-.
zon, atid at the western, an angle of from 40° to 50°. At the.
west end, the rock immediately in contact with the limestone:
is concealed, but the dark-erey aggregate appears within a few:
yards of it on the brink of the river. At the east end, this ag-.
gregate lies immediately under the curved extremities of the:
beds of limestone. See Fig. rv, in Plate XIX. |

138. On the same side, not a hundred and fifty yards be-:
low the junction of the Chlochan, and within fifty feet above:
the river, there are beds of limestone, dipping, as usual, into«
the face of the declivity, but perhaps rather more to the east--
ward. _ 7
139. At:

362 . GEOLOGICAL APPEARANCES

_ 139. At the junction of the Chlochan, the channel of the Tilt
turns at a large angle to the northward, and preserves nearly
the same direction to the junction of the Tarff, a distance of
about half a mile. The Tarff flows from the west, and, imme-

diately before it joins the Tilt, issues from a deep chasm form-

ed by precipices on either side of the channel, which, near the
outlet, is broken by two considerable falls. This spot is called
Pull Tarff. Between the junction of the Chlochan and Pull
Tarff, there appear at intervals various stratified rocks, consist-
ing of granular limestone, mica-slate, the dark-grey aggregate,
and granular quartz. Out of five positions observed with the
clinometer, if we omit one that appeared to be owing to a con-
volution, the rest argue that these strata lie round, and lean
against, the base of the mountain, which separates the valleys of
the Tarff and the Tilt. Four observations gave successively
N. 150° E., 128° E., 133° E., and 101° E.; while the dip was
getting round by the east to the north *. Our observations in
this quarter terminated at Pull Tarff. Dr Hurron mentions f,
that to the eastward of this, near Falar, he found both granite
and primary strata between Glen More and Glen Beg. In fol-
lowing up the course of the Tarff to the westward, he observed
that the strata disclosed by that river, while they stretched
about east and west, dipped to the northward. In Glen Tarff

he met with many tumbled stones, which he describes as -

“ composed of broken schistus, including white granite,’ by
which he of course means fragments of primary strata, inter-
sected by veins of white granite. He also ascended to the
summit of the ridge that separates the Tarff from the Tilt,
where he found almost every thing to be granite, and but little
of the primary strata.

140. The

* See note D. By

+ In the manuscript, of which some account is given in note C.

= a ee ee ee eee -

IN GLEN TILT: 363

140. The extent of the granite, and other crystallised aggre-
gates on this side of Glen Tilt, was farther confirmed by our
observations on the mountains more to the south, about Glen
Criny and Glen Merk. These mountains do not shew muck:
of the fixed rock, and we were therefore left 1 in most cases to
infer the materials of which they consist, from the loose blocks
that are scattered on their sides, and along the higher parts of
the courses of the streams. In order ‘to make the account as
faithful as possible, I shall enumerate the substances that we
met with, in the different lines of our walks, beginning with
what lies nearest to Forest Lodge.

143. For a considerable distance from the Griurnon towards.
Cairn y Chlannan, along the broad ridge that joins them, I
found fragments of granular quartz, and a few of granite. The-
summit of Cairn y Chlannan is granular quartz. To the south-.
west of it, the ground falls into the head of Glen Criny, which
opens into Glen Tilt..

142. In ascending from the lower part of Glen Criny to--
wards the Griurnon, but winding to the north, so as to gain
the ridge that joins it to Cairn y Chlannan, I saw loose blocks.
of granular quartz, and sienitic greenstone graduating into grey
sienite. This sienitic greenstone, and its gradations, resemble
those so abundant on the northern side of Glen Tilt, and in:
the following pages the terms always denote similar substances.
_ Through the lower part of Glen Criny, the stream runs with a
very rapid fall, for between one and two miles, over red gra=-
nite; which, as far as. 1 could judge from where the observa-
tion was made, extends to a point within two or three hundred
feet in perpendicular height, and perhaps a furlong in horizontal
distance, from the granular quartz that appears at the bridge over |
the Criny in Glen Tilt. We regret that we had no opportunity of
examining the junctionsof the strata and the granite, in the

channel

‘364 GEOLOGICAL APPEARANCES

channel of the Criny. Dr Hurron relates, that he with some
difficulty climbed up the precipitous bed of a rivulet, which
comes from the mountain on*the north side of Glen Tilt, and
which, from his description, I can only conceive to have been
the Criny. He there obtained a view of a section of the rock.
“ We first,” he says, “ found the alpine schistus inclined as on
* the south side, and heading, or rising up, to this north hill; .
immediately after which, we found the granite under the al-
pine schistus, seemingly bedded in like manner, and run-
ning parallel to the alpine strata.” It did not strike me
that the granite in Glen Criny was in parallel beds; though I
own that my examination was hasty, and I had only a distant
view of the lowest part of the Glen.

143. In following up the course of the Criny, many blocks
of grey sienite, or rather sienitic greenstone, are seen, and
many also of granular quartz. The granular quartz on Cairn
y Chlannan and in Glen Criny, contains almost always either
specks of felspar, or minute cavities similar to those already
mentioned in the granular quartz of the Griurnon. Round
the head of the Glen, the blocks of sienitic greenstone lie in
great numbers, both on the side of Cairn y Chlannan to the
east, and on that of Cairn Vardenoch to the west.

144. I ascended Cairn Vardenoch from the lower part of
Glen Criny, and kept along the broad ridge of it, winding
round to the westward, till I mearly reached that part which
overlooks Glen Merk; and returning by a different track, on
the west side of the same ridge, crossed over it, and came
- down into Glen Criny at a point higher up. In the whole of
this walk, except on that part of the ridge which lies towards
Glen Merk, I met with scarcely any thing but a small-grained
granite, having its felspar red. It appears in loose blocks, and

the

it3
14

ce

&

IN GLEN TILT. 365

the soil is formed of the decomposed ingredients. On that
part of the ridge which lies towards Glen Merk, the loose
stones are partly mica-slate, and partly grey porphyry.—On
Cairn y Chlannan and Cairn Vardenoch, there occurred also a
very few loose fragments of gneiss.
145. Glen Merk merits more attention, as it exhibits a junc-
_ tion between the strata and the granite. The name of Glen
Merk is confined to a part of the valley along that stream, ex-
tending about two miles above its opening into Glen Tilt. At
some distance from the opening, the Merk receives the Deery
from the west ; and, above this, the Glen has the direction of
due north, being formed on the east by the declivity of Cairn
Vardenoch, and on the west by that of Ben y Venny. The
head of the Glen is closed in by a rocky steep, about three
hundred feet high, connecting the two mountains, but deeply
cut by the stream, which falls through the dark chasms of a
narrow channel. 3
146. At the falls of the Merk, where the Glen opens into
Glen Tilt, there are strata of mica-slate, stretching N. 48° E.,
and dipping to the south at an angle of 27°. They agree there-
fore with the general position of the strata through the adjoin-
ing part of Glen Tilt. In following up the side of the Merk,
_to where it receives the Deery, the channel affords a transverse
section of the strata. ‘They seem to be either mica-slate, or -
gneiss ; and, as far as could be judged from a distance, they
conform in stretch and dip with those at the falls.
147. Before I proceed up the channel of the river, I shall
mention what we noticed respecting the mountains on each
side. Along the declivity of Cairn Vardenoch, at the distance
of more than a mile from the head of Glen Merk, the loose
fragments shew the higher part of the mountain to consist ei-
ther of gneiss, or of a granite, nearly the same in character

Vox. VII. P. IL. 3A with

366 GEOLOGICAL APPEARANCES

with that which occurred so abundantly upon it towards Glen
Criny. Farther up, the fragments are chiefly of gneiss; and
near the head of the Glen, they are either gneiss, or sienitic
greenstone, with its gradations.—On the side of Ben y Venny,
near the head of the Glen, we met with. sienitic greenstone in
the fixed rock, and the loose blocks. that had fallen from this
mountain were either gneiss, er sienitic greenstone; the latter
afforded gradations into grey sienite, for quartz occurred in it
frequently... Some of the blocks consisted of felspar, horn-
blende, and mica.—In ascending the steep at the head of the
Glen, on the western side of the stream, we found, the rocks,
that projected in different places from the surface, to be alter-
nately gneiss, and sienitic greenstone, but could not detenminie
their relative positions..

148. 1 now resume the description of the bed of the 3 rivers
On the eastern side of the Merk, a furlong above its junction
with the Deery, the strata are of gneiss, stretching N. 85° E.,
with a southerly dip at an angle of 22°. Fifty yards farther
up, the gneiss stretches N. 105° E., and dips to the south at an
angle some degrees larger. An hundred and fifty yards far-
ther, there is gneiss interstratified with beds of felspar porphy-
ry; the stretch is here N. 46° E. and the dip southerly at. an
angle of 28°. Three hundred yards higher up the stream, the
strata are. again gneiss, stretching N. 63° E., and dipping south-
erly at an angle of 27°. There are here some appearances of |
bendings in the strata. We saw nothing but gneiss, with its
dip southerly, in the fixed rocks, till we came within a quarter’
of a mile, or somewhat more, of the head of the Glen; when
we met with a junction of gneiss and granite, close to the east-
ern side of the streani. The strata of gneiss are much disor-
dered ; and are cut by veins,—some of granite, that is to say, a
compound of felspar, quartz, and mica, and some of felspar and

mica

IN GLEN TILT. 367

mica only. We saw here no hornblende. The granite is
small grained, and its felspar reddish, of the same colour with
that of the gneiss. The veins in some places run parallel to
the planes of the strata, and in others cross them. Some-
times there is a gradation between the vein and the gneiss,
but the line of junction is often quite distinct. Detached
pieces of gneiss, much bent, are imbedded in the granite
rock.

149. The junction is exhibited fen remarkable auaneiaes
in a rock, which lies on the brink of the stream, and has re-
ceived a polish from it. The surface here exposed measures a
few feet each way, and is nearly in the same plane, sloping ra-
ther obliquely to the water, at an angle of about 20°. (See
Plate XIX, Fig. v.) The part next the water is granite; that
next the shore is gneiss, of which the strata stretch N. 83° E.,
dipping northerly at an angle of 42°. It will be observed, that
the dip of these strata is in an opposite direction to that of all
the strata through the lower part of the Glen. The line of
junction runs for about four feet, nearly straight, in a northerly
direction, and thus crosses the lines of stratification. It igs
marked with the greatest precision. About the middle, the line
is interrupted by a small vein of granite, which projects from the
principal mass, intersecting the gneiss parallel to the lines of
stratification, and tapering away, till it is lost in the course of
a few inches. Near the line of junction, is a small fragment of
gneiss imbedded in the granite.—In the loose blocks along the
declivity of Cairn Vardenoch, we met with many junctions of
granite and gneiss, eee facts analogous to those now
described.

150. Eighty yards below the fall of the Merk at the head of
the Glen, we found gneiss, dipping about north-east, or per-
haps still more to the north, at an angle of between 40° and
45°, Near this there are large masses of granite rock, and

3 A 2 also

a a he

also veins of granite; but the circumstances of the ground
render it difficult to trace the junctions of the granite with the
gneiss. At the foot of the fall there is gneiss, lying nearly as
that last mentioned.

151. There is an obvious analogy in the appearances, at this
junction of granite and gneiss, to those at the junctions of the
sienite and strata in Glen Tilt, and they afford strong grounds
for adopting a similar hypothesis with respect to their ori-
gin.

ADDITIONAL

Roar CAA
Ty t:

;
>

PLATE XYL

OF THE
COURSE 0F THE RIVER

ye

Of

=

.

eee
a.

"
| ;
» . % ‘ .
; . 1} en ~ . a ae!
‘5 FG i as a ss

| i .4 ' P Peter jib Mees
H 7. he t f . ere 2 a « yh iy the
_3 +t a 4 i A : : 7 .
oy ' : =<). oh ae oe wrtrt WAcds Rk a
a a | a 0) - " 5 7
‘a er " i = ee ‘ weal _ —s

’ i a os < Pi Ae

“ <a SS
: ) « oe t id pam « Stratos
ay j ; 7
i oa ‘
\ Ms ; aN , — >
mS ‘ ’ =)
. My y. *
ul ‘
; re =
‘ y ‘ s
4 » j
$ - 4 ; « .%
: ‘ . .
. a Va ib ar abana Veet 2)
‘
= , ; j j

2 SA bape oll} dang ¢ Pe eee , Q + ‘ i ee Ll

PLATE XVIL

PLA wy
OF THE = A
-& Dy ow meme 0 yb 7

at A.

4B

Scale 50 Feet to an Inch.
eo Ket.

EXPLAW ATOM.
ee er a,
2 ee

idiedliteadinamtias tel ak ce oe

PLATE_XVIL

PLA wy

‘% OF THE ne
SEND ey mao
at D.

Scale So Feet to an Inch.

Bip rims

‘
ad
t
7 |
’

miele tage tua. Qerdivn salamat eM EUs m1 DY REN

Preieg wr RR iy Ayo

= > " i dye ten
ae : q on va wy ree

PIATE XIX.

i Alien Nate or Guicixs

_ Sienite

West

Bg
= Gran® Limestme
225 Grey Aggregate
ee Gy Oncol
“1a Miva Sate
: Dorherly
Fig

Here Concealed

4

me : “y
ey .

tice a4 Pee Re

yo Pe J ners

ep a verre, dete ee

*
ae “Le ren me pennies faa eeeninee

: te: ig Ser, =

ay ods dite Pe mi zy

7 eee a P

et OS ACID IR Ame tea Oy ee NE + Sg TE IE me tee,

PLATE XX_

COMPARATIVE TABLE
of the
POSITIONS of STIRATA .

NB. Te Continned tise indicates the wireteh,€ the dottestline the kbp.

By the Garry. Near Blair,
Lower part of Glen Tile.

By the Tile. By the Bannavey.

Tn Glen Tiloat B.

dn Hen Tile, wt D-

:

.

Almost

In Glen Merk,

as.
Se ee
z eis

Tip Fm Baa?

J Beet owe i. ¢
pe. Mae Eee ae “9 YJ
. lad i Gece eae, oa i

+d
BR
7
oath — ;
7 |
a -
d “~ ys
5 MN
wn
ee
x a
} .
j
I a.
: %
4 z
%
hy
» er aeatne, wtire a Le (oN rent

es

t

“—-*

: in) q
‘ *m 4 < , +
7 A i: ? "] ~ >

*,

r ae 7 o Ahiuntos West of htinburgh.
eal 50" LD PZ, 40. Ls tL 43 ae “ Za a9! 3s" 37 aa" aS" oe 3s a2" aL 30 20 2s" ey’ a a ant oe ;
! = Se = = = <= - = =

%

Water’

meresgire

ca Tare

cha ie Lock
ih oon ourt

=
/\ Ks
% |
4
Reape
4014 “0
=
H g a Sune Ninerach |
| 2k
A NR, A 18 x = wlll
\Snudiieh ae se Tatty ( PART OF
‘ a TOON 4
Je HP TEXTE RS TER TRIER ae {
} ~ Uy Jee ok sy alxare ‘
| Sf Crom bruagh = sh BES EL oO
>) Crag. Shewin g
AE on $V CII Vp Gi
GLB BOG
By) «7 \ [Menem wad the lly
‘
HY Rinockvermy Glen Prenat
Aehleanie ra Critig “Waist A Feneantivoh
ST 7 ass
Focidisheal pees a 4 eee = — 2
ee * Loinmarty 4
mu
le

2 coppuysnc
Piteldonich enw
oh

SS Hlls* “a
0 eRe reat \ x
ap SS A «lig Beg Tilt Some t nigra:
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IN GLEN TILT. 369

ADDITIONAL NOTES.

Note A, parag. 2.

In tracing up the course of the Bruar, we made the following obser-
vations.

About a hundred yards north from the road to Dalnacardoch, the
rock by the side of the river is mica-slate, stretching N. 36° E., and
dipping south-east at an angle of 37°. Immediately above this, the
river, in its descent through a long succession of falls, crosses the stra-
ta, and displays a deep section of them at the bottom of a ravine..

The prevailing rock is mica-slate.

At the first bridge in the walks made by the Duke of Atholl, there

-is a bed of grey porphyry interposed between the strata of mica-slate.

Its chief ingredient is a brownish-white felspar, in crystals that are»
crowded together, and not very distinct; and these are imbedded in a
base of compact felspar, penetrated by mica and hornblende. Near-
the second bridge, the mica-slate stretches N. 27° E., and dips.
S. E. 39°.

About a mile and a half from the road, and not far from the river, . -
there appears another bed of grey porphyry interposed between the
strata of mica-slate, The base of this porphyry seems to be compact
felspar, minutely penetrated by hornblende; and there are imperfect:

crystals of hornblende interspersed. The stretch is here N. 47° E.,
_~ and the dip S. E. 53°.

A quarter of a mile farther up, the rock is of mica-slate and gneiss,
stretching N. 16° E., and dipping to the eastward 23°.
In proceeding by the side of the river, we saw mica-slate in several

places, to all appearance conformable, in its average dip and stretch,
with that last observed.

About

370 GEOLOGICAL APPEARANCES

About four miles from the road, we found mica-slate, stretching
N. 8° E., and dipping eastward 23°.

About two miles to the north-east of this, lies Ben y Chat, the
nearest of that group of mountains, which spreads between the Bruar,
the Tarff, and the Tilt; but we found no opportunity of extending our
examination farther towards it. Among the rolled stones in, and near,
the bed of the Bruar, we saw a few blocks of sienite, both grey and
ted, and one large block of granite.

The course of the river Garry, aboye its junction with the Bruar,
lies a good deal farther to the west of Blair. In following it up, along
the road to Dalnacardoch, for between six and seven miles from
Blair, we had frequent opportunities of seeing a fine section of the
rock in the channel. The banks are abrupt, and the stream crosses
the strata almost at right angles to their stretch. Our examination of
them was very cursory ; but they seemed to be chiefly mica-slate, and
pretty uniform in their stretch and dip. About five miles from Blair,
the stretch was N. 18° E., and the dip easterly 28°. Six miles
and a half from Blair, the stretch was N. 29° E., and the dip easter-
ly 29°.

From a comparison of the observations in the beds of the Tilt, the
Banavie, the Bruar, and the Garry, it appears that the strata, which
would be crossed by a line passing through Blair a little to the north
of west, and extending about seven miles in that direction from the
Tilt, are conformable in dipping towards the south-east; but vary in
the extreme differences of their stretch about forty degrees.

The strata in the channel of the Garry are intersected by veins, or
dykes, of porphyry. About five miles from Blair, there is a remark-
able one crossing the river, and between twenty and thirty yards
broad. The base of this porphyry is a reddish brown compact felspar,
in which there are imbedded small crystals of white felspar, and very
imperfect crystals of hornblende. Where the porphyry joins to the
mica-slate, the colour of the base changes to black by a gradation
in the course of a few inches. Of this circumstance I can offer no ex-
planation.

Six miles and a half from Blair, there is a bed of porphyry perfectly
parallel to the strata, and uniform in its thickness, which is oe

eet.

IN GLEN TILT. 371

feet: This porphyry has for its base a brownish-red compact felspar,
which is well characterised, and contains crystals of quartz thinly in-
terspersed. Its red colour makes it very conspicuous on the banks of
the river, and the outgoing of the bed may be traced on both sides in
the slopes of the mountains.

Note B, Parag. 120.

The minuteness, and intricate reticulation, of the smaller veins,
may be urged in support of the hypothesis of secretion. In these
points indeed they resemble those veins of quartz, and of calcareous
spar, which are often found running in all directions through various
stratified substances, and which it is difficult to conceive. any other
process, but secretion, to have produced. However, after having re-
jected the hypothesis of secretion for the larger veins of sienite, it
would be absurd to have recourse to it for the origin of small veins,.
which are evident ramifications, and gradations, from them.

The gradation on the sides of the veins in some places may also be
insisted on, as favouring the hypothesis of cotemporaneous formation
by secretion. But distinctness, or gradation, on the sides of veins, are
equivocal circumstances in a question about their formation That
distinctness will not prove posterior formation, is evinced by its oce
curring in veins, which there is every other reason to suppose secret-
ed; as in the minutely ramified veins of quartz running through
clay-slate; in the small veins of calcareous spar in limestone; in the
veins of calcareous spar, which cross dykes of whinstone, and do not
penetrate their walls * ; also in the lenticular veins of brown spar, or

spathose

* A good example of this occurs in the dyke that crosses the Water of Leith,
above St Bernard’s Well.

372 GEOLOGICAL APPEARANCES

spathose iron-ore, in nodules of argillaceous iron-stone. On the
other hand, that gradation is no decisive mark of secretion, is proved
by instances of it on the sides of veins, of which the posterior forma-
tion is undoubted. Werner mentions examples of it*; and Mr Ja-
MESON observes in his Geognosy, where treating of such veins, that
there are “ cases in which the substance of the vein is intimately mix-
“ ed with its walls ft.” A fact of this kind was met with in Corn-
wall in the year 1799, when Mr Prayrair and myself were in that
country. A mine near Redruth, called Toll Carne, was then work-
ing in a vein containing tinstone. The walls were of granite, and
crystals of tinstone were found disseminated through the granite, for a
few inches from the sides of the vein. It was regarded by some ex-
perienced miners of that district, as quite a singular instance; but
WerNER mentions similar facts concerning tinstone {.

An analogous example of gradation was -described to me bg Sir
Humeury Davy, as having been seen by Mr Grernovueu and him-
self, on the shore of Loch Erne in Ireland. A projecting rock of con-
siderable height, so as to render it a conspicuous object from a dis-
tance, was found to consist of a large vein of trap, or dyke of whinstone,
traversing strata of limestone nearly horizontal. At the distance of
some yards from the vein, the limestone presented the usual characters
of that substance; but, on approaching the vein, it grew more in-
durated, and to all appearance siliceous, and was highly so, where in
contact. The softer parts of the strata were much worn away, and
had left the harder parts on the sides of the vein, to form with it a pro-
jecting mass.

At Beadnel Bay, on the coast of Northumberland, there is a whin-
stone dyke, cutting strata, some of which are of limestone, and exhi-

bit near the dyke a change of character very analogous to that just
described.

* See Theory of Veins, § 58, 72, 75.
+ P. 232. See also p. 239.

+ See Theory of Veins, § 72.

IN GLEN TILT. 373.

described. An account of this dyke was laid before the Geological
Society of London, in a paper by Mr Bennett, read in March 1812.
A notice of it appears in Nicholson’s Journal, for April 1812, which is.
the source of my information.

Note C, Parag. 133.

When Dr Hutton communicated his views respecting Glen Tilt to:
the Society, he signified his intention of giving at some future time a.
full description of the phenomena he had observed ;. and, in the first
volume of his Theory of the Earth, he promised to introduce it in the
course of the work. At his death he left.a third volume of this publi-
cation nearly ready for the press) Mr Prayrair has favoured me
with a sight of the manuscript, which contains a more particular ac-
count of the author’s observations upon the junctions of granite and:
primary strata, in Glen Tilt, in Arran, and in Galloway. His descrip-
tions are not minute, but were to have been illustrated by en-.
gravings, from drawings made on the spot; partly by the late Mr-
Cuierk of Eldin, who accompanied him in two or. three of his minera-
logical excursions. When describing the appearances in the bed of
the Tilt, he says, “ The granite is here found breaking, and displa-
“cing the strata, in every conceivable manner, including the frag-
“¢ ments of the broken strata, and interjected in every possible. direc-
« tion among the strata, which appear. This is to be seen, not in one
“* place only of the valley, but in many places, where the rocks ap-
«* pear, or where the river has laid bare the strata.” If Dr Hutton
has called the sienite granite, this can hardly be considered as a mis-
take in nomenclature at the time when. he wrote; and, though the
Wernerian School have insisted much upon the distinction of those
substances, it appears of little consequence in forming a theory for the-
origin of that great tribe of crystallised aggregates, to which they

Vou. Vil PIL 3B both:

374 GEOLOGICAL APPEARANCES

both belong. Dr Hurron’s chief error in describing ‘Glen Tilt is,
that of stating the mountain on the northern side of the valley to con-
sist of red granite. He was probably led to this false inference, by
what he saw in the deep cut made by the Criny, and by loose
blocks near its entrance into Glen Tilt. x”

a

Note D, Parag. 139.

About sixty yards above the junction of the Chlochan, there are
“seen, in the bed of the Tilt, strata of a white granular limestone, high-
ly crystallised, interstratified with, and penetrated by, mica and felspar,
and containing pyrites. The mica gives it a slaty fracture in the
large. ‘The greater facility with which the carbonate of lime is worn
away by the water, has caused the felspar to stand up in some places,
in a rough and porous crust, on the surface of the rock. The position
of these strata differs much from that which is most common in Glen
Tilt; for their stretch is N. 150° E., and their dip noith att Stan
angle of 41°. Those on the eastern bank of the river are cut by red

veins, either of felspar or sienite *. .

A hundred yards farther up the stream, I again fell in with the
dark-grey ageregate. oie

A hundred and fifty yards higher, there are strata in the face of.
the hill above the southern bank, which seem to be,limestone.. They —
dip to the eastward into the face of the hill, but are much bent.

In the course of another hundred yards, the dark-grey aggregate
again occurs in the bed of the river. cals

A hundred and fifty yards farther up, there is mica-slate, stretch-
ing N. 128° E., and dipping to the north-east at an angle of 45°,

The stretch and dip of the strata, where distinct, continues much

the same for a hundred and fifty yards, when there appears mica-
| slate,

# This is one of the exceptions alluded to in parag. 110.

IN GLEN THLT. | 375

slate, stretching N. 133° E., and dipping to the north-east from 30° to
35°. About a hundred and fifty yards above this, is the junction of.
the Tarff and the Tilt.

On the southern bank of the Tarff, fifty yards below the fall nearest
the junction of the two rivers, the rock is of granular quartz, contain-
ing some felspar, and steatite in the small fissures. It effervesces
slightly, and seems to be penetrated with carbonate of lime. The stra-
tification of this rock is indistinct, but, as far as I could determine it,
its stretch is N. 93° E., and its dip southerly 46°. On the opposite
bank the rock is of the same character. Its stratification is very indi-
stinct, but appears to be horizontal, or rather dipping to the north.
On the southern bank, nearer to the fall, there are strata of mica-
slate, very distinct, stretching N. 101° E. and dipping northerly
38°. Some of these strata are only thirty yards from the granular
quartz, which has nearly the same stretch, and dips at nearly the same
angle, but in an opposite direction. As these strata were, no doubt,
once conformable, there is reason to imagine that they have undergone
an extraordinary convolution, and some fraces of it may be discovered
in the intervening face of the bank, though it does not afford so clear
a section of the rock, as could be wished.

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wil. Xion certain Appearances observed in the Dissection of the
Eyes of Fishes. By James L, Drummonp, M. D.

of Belfast. Communicated by Dr Tuomas Brown, Pro-

fessor of Moral Philosophy in the University of Edin-

burgh.
(Read 2d May 1814.)

1 OME months ago, in investigating the anatomy of the eyes
J of fishes, I washed off the back silvery part of the choroid
coat of the haddock, with a hair pencil, and about half a tea-
spoonfulof water. The latter became of a milky colour, and on ex-
amining a drop of it, with an Exxts’s aquatic microscope, I found
the milkiness to be owing to innumerable slender, flat, silvery
spicula, which had composed the substance of the choroid.
They seemed to be in constant motion, apparently rolling up-
‘on their axes, but having no degree of progressive movement.
The light reflected from their surface was very brilliant, like
that from polished silver, and often disappeared, and again re-
turned, with alternations so rapid, as to produce a twinkling,
very like that of a fixed star.
Sometimes, on examining an individual specimen, it would
disappear altogether, but in a few minutes return, renew its
twinkling, and apparent revolution on its axis, and again dis-

‘appear, to return as before.
Frequently

378 APPEARANCES OBSERVED IN THE

Frequently also, some were observed to be in the fluid, or
on its surface, for a long time motionless, but very brilliant ;
then they would give a few slight twinkles, seem to turn round,
and almost disappear; then resume their original situation for
@ moment, appear more brilliant than at first, partly disappear
again, and again return, and so on, for a number of times, till
at length they would disappear entirely ; but, after a time, per-
haps' five or ten minutes, shew themselves in ‘the same spot as
before. These observations could be made only on the larger
spicula ; the minute ones being 1 in incessant motion..

On the first examination of this appearance, it seemed pro-
bable, that the motion might be communicated by animalcula
swimming through the fluid, and that these had been propaga-
ted after the death of the fish, as the eye was not quite fresh.
Soon afterwards, however, I examined the choroid in the same
way, from a flounder before it was quite dead. The same ap-
pearance presented itself, if possible still more lively ; and I
found also, that it continued in many of the aon after ex~
posure to alee of boiling water:

Since that period, I have observed the same phenomena i in
the choroid of all the fishes which I have examined, in the
cartilaginous as well as the bony.

The motion continues ina great many of the seiadied even
after the fluid containing them has become putrid; but it is
then more slow. The addition of ardent spirit deadens, but
does not destroy the motion. After exposure to a heat of
boiling water, the number of spicula seems much diminished,
and those which remain move less rapidly than before. The
addition of vinegar, in a quantity equal to the fluid containing
the spicula, suddenly causes a great diminution of the number
ef moving ones, probably from Setiealiias the albuminous mat-
ter, wilted had been washed from the eye” along with the spi-

cula,

EYES AND SCALES OF FISHES. 379

eula, and entangling them in it. Many, however, continue
their motion as before. | .
Whether these bodies really turn upon their axes, or whe-
ther they have the property of producing a rapid renewal and
cessation of reflection of the rays of light, from their surfaces,
so as to produce only the appearance of rotation, I cannot po-
sitively determine. In the larger spicula of the choroid of the
herring, I have certainly, sometimes, been able to trace the
opaque outline of an individual spiculum, after it had ceased
its twinkling reflection ; but, in general, the appearance of ro-
tation seems so distinct, as almost to preclude the supposition
of its not really taking place ; and these bodies are not so mi-
nute as to admit of much optical deception ; for in those from
some fishes, the herring im particular, the reflection, and ap-
parent motion, are quite evident, in the sunshine, te the naked
eye.

The spicula of the eye of the herring are jointed, being ge-
nerally thus divided into three distinct portions, of which that
which forms the centre is much larger than the two others.
In common day-light, the entire spiculum is silvery ; but if it
be observed in the sunshine, it will be found to reflect different
rays, from the different jointed portions; the end-joints being
generally of a light straw colour, while the central one is steel-
blue, like the main-spring of a watch, or of a red or light rose
colour, sometimes silvery, green, or purple ; but never of the
same colour as the extremities of the spiculum. The colours
of the different joints do not shade into each other, but ter-
minate abruptly by a well-defined line.

To account for the motion of these spicula is digsrult
There seems no reason to suppose it to depend, either on elec-
trical or galvanic influence. The motion of each spiculum is
proper to itself, nothing like attraction, or repulsion, subsisting

between

880 APPEARANCES OBSERVED IN THE®

between it and any other, or between it and e
or bottom of the fluid.

Evaporation, causing an intestine motion in the particles of
the fluid, cannot be the cause; for the addition of ardent spi-
rit, which increases the etmateleied, deadens the motion, and.
the motion continues when the liquid is covered over with al-
mond oil, or inclosed in a glass tube. © ‘og hals

The spicula are a little heavier than water ; for, on standing,
they slowly settle at the bottom ; but the slow manner of their.
subsiding, and consequent turning, from side to side, is not t the.
cause of the motion mentioned ; for when a stratum is spread.
on a piece of glass with a hair-peneil, as thin as possible, the
motion continues till the whole water is evaporated ; and if a
drop of oil is let fall on such a stratum of. fluid containing the
spicula, the motion continues under the oil without interrup~
tion for many hours..

The transmission of caloric will in no way account for it..
The motion is totally different from that of particles of dust,
&c. caused by the currents formed duniag the cooling or ek
ing of alcohol or other fluids..

Phosphorescence has no connection with it; the reflection:
being apparent only when light falls on the surface of the.
fluid ; and the stronger the light the more brilliant, as in other
cases, is the ebilection.

To suppose that these spicula are animated, would, for ma-
ny reasons, seem a wild and improbable idea.

First, They resist a heat of 212°, which no animated being is
known to do. 2)

This alone might at first seem conclusive, yet, perhaps, it is
not entirely so. The experiments of naturalists prove, that
the ova of animalcula resist a boiling heat, as, in various ve-
getable decoctions, which, although poured hot into oe

anc.

er the surface

EVES AND SCALES OF FISHES. _ 381

‘and immediately corked up or sealed over, yet are found, after
some hound ageays, to be replete with myriads of animalcu-
les; but I believe no experiment goes to shew, that any ani
malcule could itself withstand such a degree of heat. In these
obscure departments of nature, however, there is no paboning
with certainty from mere analogy.. Before Tremniey’s disco-
very of the nature of the polypus, it could scarcely have been
credited, that there existed any animal which might be multi-
plied almost ad infinitum, by cutting it into pieces; and there
are many other phznomena in the animal kingdom, which
stand as it were insulated and independent of the laws which
govern the ‘chain of animation to which they belong. Thus
vinegar proves an instantaneous poison to all animalcules found
in other fluids, yet the vibrio aceti is found in vinegar, and in
it alone, Some animalcules, after being dried up for years, as
the eels in blighted wheat, revive upon the application of moi-
sture ; and the insect named the puceron, or vine-fretter (as
discovered by Bonner), contrary to all analogy, propagates
without sexual intercourse down to the ninth generation.
From these, and many other similar occurrences, it must be
evident, that analogy, in our researches into the lowest classes
of animal life, must be a fallacious guide. Perhaps, therefore,
without too far transgressing the bounds of probability, we
may admit the possibility of the existence of a being possessed
of animation, and yet capable of resisting a heat as high as
Qi".
Second, It appears very absurd to suppose, that any organ of
a living body should be composed of a congeries of otha mi-
nute shivaideind beings or an le
But, at one time, it sro di@ierhayis have seemed nearly as
great an absurdity, to suppose that such beings existed in any
of the secretions ; yet the discovery of LizuwEenuorcx, and the

Vou. VII. P. ID. 3C observations

382 APPEARANCES OBSERVED IN THE Z

observatlons of succeeding philosophers have proved, that im
the seminal fluid animalcules do exist. in t atest abun-

dance. ¢

many ‘onidiaalk are “fxd ‘og one at from the firse moment of
their existence till that of their dissolution. I need only
mention some of the festacea, as the lepas, anomia, and ser-
pula; and the numerous zoophytes, the inhabitants of which
remain for ever fixed, each to the cell which gave it birth.
Even in the human. body, we find the various species of hy-
datids under the same circumstances. ~~ ‘

Fourth, Animalcules increase in number by long ass
and putrefaction ; on the contrary, these spicula, by the same:
means, become greatly diminished in number.

Here it may be observed, that when animalcula thus in-
erease, they are in their natural and proper element ; but the
spicula, when removed: from the eye, are in the same circum-
stances as. intestinal worms. or hydatids, which, when removed
from the body, soon die. Besides, the life ofthe animal which
they infest, seems necessary to the continuance of their being ;
for after the death of the animal, (as‘in the case of removal,).
they soon die also. Hence, allowing these spicula to be ani-.
mated, the wonder may rather be, how they retain their ani-
mation so long after being removed from their natural situa-
tion. It would, however, only be another instance of the ex-
traordinary power by which some animals retain vitality, as is
strongly evinced in the frdgor @- which are said to leap or
move about even twenty-four h after the head has been ta-
ken. off, or the heart cut out. |

’ With:

EYES AND SCALES OF FISHES. 383

With regard to the little effect which ardent spirit produces
on the spicula, it may be remarked, that scarabzei, and other
_ coleopterous insects, often remain a considerable time immer-
sed in spirits before they become motionless, and, when taken
out after a lapse of four or five hours, frequently recover.

_ Fifth, Are not these spicula formed and nourished by blood-
vessels as the other parts of the fish are; and, if so, how can
they be considered as distinct animals? This question, it must
be confessed, is almost unanswerable. To prove that vessels
cannot be traced into them, would be to prove nothing ; for in
many parts of the body, as the cartilages of the joints, ves-
sels cannot, even by the finest injections, be detected. The -
spicula are chiefly abundant in the cellular substance which
connects the outer layer of the choroid to the sclerotica, and
there they seem to have little or no adhesion, at least not more
than would seem to arise,from their confinement among cellu-
lar substance. Hence, in merely separating the choroid from
the sclerotica, they are obtained in thousands. When the
choroid also is dissected off, and gently shaken in a phial with a
little water, the liquid very soon becomes milky, from their
dispersion through it.

This looseness, or want of connection, is, however, of little
consequence with respect to the present argument, since the
brain or the pulpy retina may be diffused through water with
almost as mavichipense, yet both are perfectly vascular. The
particles, however, into which the brain or retina is broken are
quite irregular, and of different sizes or clusters, and of pulpy
_ consistence, and exhibit no appearance of motion. The spi-
cula, on the other hand, seem, to be rigid, are always distinct,
and of a constant determinate. form, and keep up a perpetual
motion and reflection of light.

3C2 Perhaps

384 APPEARANCES OBSERVED IN THE

Perhaps many other objections. may be opposed to. the sup-
position of animalcular life in these bodies ; and yet the strong
expression of animation, if I may so term it, and air of seeming,
design, with which the varying motions, sometimes slow, and
sometimes rapid, are performed, and the difficulty of otherwise.
accounting for their motion, whether real or apparent, lead,
upon the whole, I think, to this supposition, not as one which,
we can admit with confidence, but as the least improbable con-
jecture, which, in the present limited state of our ‘nordadaas .
we can venture to. form..

. Tn managing the microscope; tHe reflector must not be used
for when a strong light is transmitted through the fluid, the
spicula become invisible, or are only imperfectly seen. The
fluid, therefore, containing them, should be placed upon some-.
thing of a, dark colour, as a piece of glass, with its underside
blackened; and, the stronger the ight which can be thrown
upon the surface, the better; hence they appear uncommonly
brilliant and distinct when placed in the sunshine; and, in this
situation, with a high ed they present one of the most
brilliant and lively microscopic objects that can be imagined ;
each spiculum seems like a long bar of light, constantly twink-
ling, with a refléttion almost too strong for the eye to sustain.
They may be also well seen in a strong candle light, so mana-
ged, that it may fall upon the surface.

Perhaps this phzenomenon may have been “already. pointed:
out; but it is not noticed by Apam, Cuvier, -BLUMENBACH, or.
any author with whom I am acquainted.

# t. * Sinee

EYES AND SCALES OF FISHES. 385

rR aT eS tcc

Since these observations were originally made by me on the
spicula of the eye, I have been led to extend my inquiries to
other parts of the fish ; and though I have not yet had time to
- vary my observations as fully and widely as with more leisure
I would have done, I may state even now, that I have ascer-
tained beyond a doubt, that the brilliant colours of the surface -
of this splendid tribe of animals are not owing, as Cuvizr sup-
poses, to a mucous * substance, but to bodies in every respect.
the same as the spicula of the choroid coat of the eye. The:
scales of fishes are pellucid; and their brilliant appearance is |
owing to a thin film, which covers the underside of each scale,
and is itself entirely formed of spicula, as is easily proved by
scraping off a quantity of scales, and agitating them in water
with a stick or other body, so as to detach the films. The wa-
ter will then be found to contain thousands of moving spicula,
which, in the sunshine, may be discerned with the utmost ease -
by the naked eye. ‘The scales of the salmon answer best for -
this purpose, as they are large and easily =

* « Of all vertebral animals,” says this illustrious physiologist, ‘fishes are
the most remarkable for the brilliant and metallic colours which their rete muco-
sum exhibits. We find in thém gold, silver, and copper, tin, lead, and even all
the tints which these metals assume in different degrees of oxydation. But as
the description of these colours is the province of Natural History, properly so
ealled, we wish merely to point out in this place, that they are produced by the
mucous substance which adheres closely to the internal surface of the scales, and :
with. which. it is frequently penerediiiyecct. XLV.

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XII. Observations on the Theory of Language. By Henry -
Dewar, M.D. Fellow of the Royal College of Physi--
cians of Edinburgh.

(Read 2d January 1815.)

HOSE philological. studies which have been cultivated '

among polished nations, for their subserviency to litera- -
ry taste, and their influence on the formation of correct habits -
of speaking and writing, have gradually suggested the more -
profound science of Universal Grammar. The business of this
science is, not merely to dictate the best manner of connect-
ing words with one another, but to. investigate the origin of .
the various distinctions existing among them, and to disco-
ver in what instances these distinctions are dictated by occa-
sional. convenience or partial caprice, and in what. instances
they are essential to the purposes of language. By the aid of ©
these investigations, philosophers have even hoped to trace _
some of the most important laws of human thought, and to -
obiain a solution of the most. difficult problems of me- .
taphysics. Some of the attempts made to realise these expec- .
tations. have displayed great ingenuity; but, even with this.
qualification to recommend them, they have often failed to.
establish principles on a foundation sufficiently sure to preclude:
controversy.

Amidst

“288 OBSERVATIONS ON THE

Amidst the equilibrium of sentiment on such subjects, and
the consequent indifference to the investigations themselves
which previously prevailed, Mr Horne Tooke published his Di-
versions of Purley,—a work which must be ee not
only to exhibit a brilliant display of the genius of the author, -
but to afford a luminous explanation of some points in the’ sci-
ence that were formerly obscute.

This author has refuted some of the errors of his predeces-

_sors with so much clearness of argument, and exposed their
incongruities with such forcible effect, that it might naturally
have been expected that these errors would not have been re-
peated. But his lucubrations have laboured under some disad-
vantages. ‘The circumstance of his declining to deliver his

- opinion on some important points has prevented his readers

from appreciating the merits of his doctrines, or even from
perceiving whether or not he was in possession of a complete
system on the subject : while the boldness of his asseverations,

_ the acrimony of his polemics, and the delight which he betrays
in confounding the self-ecomplacency of those whom he regards
as less. enlightened, have probably cherished, in many an his
readers, a prejudiced attachment to errors which might other
wise have been considered as exploded.

It is on all hands allowed, that Mr Tooxe had the merit of
giving this department of inquiry a more interesting character
than it formerly possessed ; and those who are disposed to read
his work with a view to information, and to pass over all that
is dark or uncertain in it, cannot fail to be much instructed.
Even where he appears to aim at the subversion of sound and
highly valued principles, the facts on which he proceeds are.
deserving of careful attention; and though we may for a time
fail in Bidet ouring to account for them, they are worthy of

being

THEORY OF LANGUAGE. 389

being recorded for more complete investigation, as promising
to lead us to new and unexceptionable conclusions.

The design of the following paper is to suggest a few consi»
derations for the purpose of solving some difficulties in which
the Theory of Language is involved.

It will be requisite, in the first place, to consider minute-
ly the opsecrt or purpose of Language,—a subject which
the greater part of writers, and Mr Tooke himself, seem to
have thought liable to no diversity of opinion, and which is in-
troduced at the beginning of every treatise on universal gram-
mar, rather for the sake of form than with a view to establish
any peculiar doctrine.

No grammarian seems to have disputed the justness of this
account of the object of language, that it is “ to communicate
“ our thoughts to one another.” |

We communicate our thoughts, sometimes by presenting the -
objects of them to the senses of another; sometimes by sug-
gesting them through the medium of signs. When we hold
out an apple or a stone, when we point to a river or toa
mountain, we communicate to another a thought which exists
in our own mind. This act has been reckoned a specimen of
natural language. It is, however, with signs, and only with
that species of signs called words, that universal grammar is
conversant ; and, in our inquiries into this subject, we are to
consider the use that is made of these signs, as completely se-
parate from any immediate exhibition of the objects of our
thoughts themselves. _

Words are, indeed, objects of thought, and are perceived,
like other objects, by the senses. They are not, however, pre-
sented on their own account, but only for exciting different
ideas, for which they conventionally stand as signs. The ori-

Vou. VII. P. II. 3D” ginal

396 OBSERVATIONS ON THE

ginal objects must have been at some time presented, in order
that the words may be understood ; but, when once understood,
they perform their office without that aid.

All thoughts which are communicated, must either be affec-
tions received immediately from the perceptions of external
objects, or affections which become communicable in conse-
quence of certain relations nak oe existing betwixt them and
external objects.

In communicating thought, we sometimes merely recall
thoughts which had on some former occasion existed in the
mind of the person addressed ; at other times we convey new
ones. This last is the case when we give a person new infor-
mation.

It is not, however, possible, that any thought whic is com-
municated by words should consist of new sabncbsiats' ; because
every word, in order to serve the purpose of communication,
must be previously understood. All new thoughts, therefore,
communicated by language, consist of new conjunctions of ideas,
produced by new arrangements among the words that are used:
From differences of arrangement given to the same ideas, new
feelings may arise. The varieties of sentiment, depending on
the varieties of these arrangements, constitute, in a great mea-
sure, the varieties of character and of intellect that exist among
mankind. By the use of language, as subservient to these ends,
the great fabrics of science and literary taste are erected.

We must, therefore, understand by the communication of
thought to which language is subservient, the act of commu-
nicating new arrangements of such ideas as were formerly pos-
sessed. The resulting feelings are subsequent consequences,
which we have it in view to produce ; but the conveyance of
them is not the immediate act of language itself:

| | Mr

THEORY OF LANGUAGE. 391

Mr Tooxer does not explicitly say, that he considers all Jan-
guage as consisting in expressing the connections of ideas ; but
he seems to make some approach to this doctrine. He ac-
knowledges only two essential parts of speech, the Noun and
the Verb. The Noun he defines to be “ the simple or com-
“¢ plex, the particular or general sign or name of one or more
‘“ ideas.” The Verb, according to him, is “ the word by which
** we make our communication.”

In the outset of his speculations, he denies that the mind
has any farther concern with language than to receive impres-_
sions, that is, to have sensations or feelings. What are called
its operations, he says, are merely operations of language. This
distinction is perhaps rather frivolous. If language is a human
contrivance, both the creation and the application of it must
be operations of the mind. He must therefore mean, that it
implies no farther operation of the mind than what consists in
the contrivance and employment of the means of communica-
tion. | HF

“ The consideration of ideas, or of the mind, or things, rela-
“ tive to the parts of speech, will,” he says, “ lead us no far-
“‘ ther than to Nouns, that is, the signs of these impressions,
* or names of ideas: The other part of speech, the Verb, must
“be accounted for from the necessary use of it in communi-
“ cation. The Verb is, guod loquimur ; the Noun, de quo.”

This author, however, has not given a full account of the
doctrine which he entertained respecting the nature of the
Verb. In the end of his second volume, he seems to concur
with other grammarians in believing that the idea expressed
by most verbs may be expressed also by means of a noun.
He says, “ the verb always contains a noun, but, besides this,
* contains something more ;” and he proposes it as an enigma
for exercising the acuteness of the metaphysical world, “ what

38D2 : “ is

392 OBSERVATIONS ON’ THE

“is that peculiar differential circumstance which, added to the
‘“. definition of a Noun, constitutes the Verb?” In ano-
ther part of his work, he refuses to the: infinitive mood: of the
verb the character of a noun, although it appears to be the
mere name of the idea contained in the verb. The infinitive
mood, indeed, is connected with some of the words in a.sen-
tence in a manner differing a little from other nouns; but in
more important points of syntax it agrees with them. Mr
Tooxe, however, appears to have considered the radical use of
the infinitive. mood’ as the same with that of the verb as dise
tinguished from the noun, and not as, in this respect, analo-
gous to the noun itself: It is difficult to reconcile this doc-
trine, not only with other doctrines of Mr Tooke, but with one
obvious fact in language itself,—that, wherever the infinitive ofa
verb occurs, an additional. Verb will serve the purpose of eom-

pleting a sentence, but the addition of a Noun will not. If -

we take the infinitive of the Verb “ to deceive,’ we never
can complete a sentence by adding the Noun “ man,” “ friend,”
or “ stranger: but we can complete one by adding the Verb
“ dishonours.” ‘ To deceive dishonours,” is a complete sen-
tence, though not an elegant one. It is not easy to. form
even a probable con jecture what views Mr Tooxz could enter-
tain of the Verb, in strict SpnEISIPRAR with other doctrines
which he advances.

The theory adopted by some grammarians who have availed
themselves very fully of the improvements of Mr Tooxx is, that

the proper business of language is AFFIRMATION OF ASSERTION ;

that all sentences, when analysed, are resolved into assertions ;
that assertion is the connecting of one idea. with another ; and
that the office of the verb is to. serve as the sign of connection
betwixt different ideas. The Substantive Verb is, in this theo-
vy, considered as the only pure verb, and all other verbs are
supposed to Be made up of the Substantive Verb and a =

1;

THEORY OF LANGUAGE. 393

In fact, the substantive verb is considered as the simple ex-
pression for “ that peculiar differential circumstance which,
“ added to thedefinition of a Noun, constitutes the Verb.”
This is the view adopted by the learned author of the article
Universal Grammar, in the later editions of the Encyclopedia
Britannica. |

This doctrine does not seem, however, to be acquiesced in
by all. The ingenious author of the corresponding article in
Rees’s Cyclopedia, though he does not directly oppose it,
seems not to consider affirmation as essential to language. He
casually speaks of the verb as losing its power of affirmation
in the Imperative: Mood. He has not, however, substituted
any other theory of the general object of language, nor laid
doww any general doctrine on the nature of sentences. He
does not, indeed, shew himself to be aware, that since, in this
instance, he denied a doctrine reckoned by others fundamen-
tal, it was incumbent on him either to substitute another, or to
prove that none could. be obtained.

.

The theory which considers the business of language as con- -

sisting in affirmation, and which considers all sentences as as-

sertions, is certainly recommended by some share of plausibi-.

lity. We feel, for the most part, that.this.is our object. We
use the noun as the sign of an idea, and the verb as a sign by
which we communicate a new connection betwixt one. idea.and

another. The substantive verb, placed betwixt. two nouns,

signifies that the ideas expressed by these nouns have a cer-

tain order of succession in our thoughts,—an. order which we
endeavour, by means of this sign, to produce in the thoughts
of the person to whom we speak. “ This cloth is green,”
when’ addressed to any person, signifies merely that we con-
~nect the idea expressed by “ this cloth” with that which is-ex-

pressed by the.term “ green.” ‘The assertion made is, that a
green:

394 OBSERVATIONS ON THE

green colour is an object which has a definite connection with
that congeries of other qualities to which we attach the name or
description of “ this cloth.” |

From sentences expressing the simpler combinations of
ideas. we ascend to the formation of others of a more compli-
-eated kind. Of this we have an instance in de scribing the lo-

/ situation of any object. We still only use nouns and verbs
= expressing a certain order of ideas. We mention one or
more objects to which the chief object of our interest bears some
local relation. It makes no difference in the general nature of
the act of language, whether these others are previously known,
or are now first brought into view for the sake of specifying
the relations sustained by that which we intend to describe.
The series is still more complicated, when we give an account
of a change of place which any object has undergone. We
now describe a series of ideas composed. of two or more sim-
pler series. We assign to the object a particular situation at one
moment, and describe its situation as different at a succeeding
moment. This is implied in all our ideas of motion, on which
the greater part of Active Verbs are founded,—simple as they
appear, in consequence of the instantaneous resulting senti-
ments gcse habit has led us to attach to them. The verbs
“to go,’—* to run,” —“ to strike,’ to kill,’—derive their
difference of meaning from ees th of arrangement which
the same original ideas are intended to assume.

These doctrines concerning the Noun and the Verb, and the
universality of the character of Assertion in the composition of
sentences, cannot, however, be maintained, unless it can be
shewn that all the differentgkinds of sentences are actually re-
solvable into assertions, and are originally possessed of that
character. Its application to such sentences as I have now al-
luded to is sufficiently obvious. It might also be shewn to be

applicable

THEORY OF LANGUAGE. 395.

applicable to Negations. But how will it apply to Imperatives
and Interrogatives? This is a question which deserves parti-
cular attention. © |

The author who writes in the Encyclopedia Britannica, re-
duces Imperative sentences to Assertions, by placing before
them the affirming words, “ I command you,” or, “ I request
“‘ you.” The imperative “ veni,” he says, is exactly equivalent
to the assertion “ jubeo te venire.” If all imperative senten-
ces are assertions, Interrogatives will easily fall under the same
denomination, as they are only imperatives in a different
form. By interrogatives, we request the person whom we ad-
dress to give us information. “ What is your name?” and
“ Tell me your name,” are equivalent; and both are resolved:
by this theory into the affirmative sentence, “ I beg that you:
“ will tell me your name.” The Imperative mood is thus con-
sidered as an abbreviation..

This doctrine, as applied to Imperatives, however, is unsatis-
factory. ‘The brevity of Imperatives has every appearance of '
being part of their original character. The words prefixed by
the author now mentioned do not seem. natural to such sen--
tences, and tend rather to encumber than explain them. The
sentences into which they are then reduced are, strictly speak-.
ing, mere assertions of a command or request, and no longer
the giving of a command itself’ But a command must exist
before it can properly be asserted, and no command exists be-
fore the Imperative is used..

With a view to substitute a different doctrine on this: sub-.
ject, I shall. premise a few general considerations which are:
necessary to give us right notions respecting the mutual influ-
ence of thought and language. I begin with remarking, that.
we should avoid the error of supposing that language is mere-
ly a simple and spontaneous expression of our thoughts. A.

notion

396 OBSERVATIONS ON THE

notion has of late obtained general currency among metaphy-
sicians, that, wlien we speak, we merely think aloud, and that,
when we think, we merely speak in secret. ‘The closeness of
the connection betwixt thought and language has thus been
overrated. The origin of this error may be traced without
much difficulty. It is to Language that we owe the greater
part of our information. This circumstance creates an attach-
ment to Language which sometimes leads us astray. Another
circumstance possessed of the same tendency is, that when we
are engaged in private thought, we very generally have some
nearer or more distant view of expressing our ideas to others.
It is also to be remarked that, independently of any direct inten-
tion, we are prone to indulge the pleasure of associating our men-
tal exercises with the imagery of conversation. Thoughts which
are thus associated are most apt to be attended to and revolved in
the mind. But it ought to be recollected that many thoughts
pass through the mind which are never expressed, and have no
necessary connection with language whatever.—We sometimes
hear it maintained, that we cannot think except.through the
medium of language, This is to suppose that we never think
of an object, before the name of that object occurs to us. Ac-
cording to this theory, the name and the thing represent-
ed by it are not even allowed to be. strictly collateral.
The precedence in point of time is given to the name. A
little reflection on the varieties which take place in the usual
current of thought will soon lead us to regard the opinion now
mentioned as immature. It will probably be found that,
though the occurrence of a word sometimes suggests the ob-
ject which it signifies, the occurrence of the object to the mind
as frequently suggests the word which is employed as its name.
Whether we think of words or of things, both the one and the
other are to be equally considered as Objects of thought, and in

neither

THEORY OF LANGUAGE. 397

neither case can we be said to think through the medium of ©
Language in any other sense than that which is implied in the -
familiar fact, that one kind of thought readily suggests another
_with which it has been associated... The cause of this error
seems to be, that our thoughts about words and things are in- -
timately mixed, and the transitions from the one to the other -
too rapid to be perceptible. Another cause is, that our most
considerate speculations are generally subsequent to some -
looser movements of the mental faculties, in which many
words are revolved, for the aid which they afford by suggest-
ing a variety of views. Men, to be sure, very often imagine
themselves to be speaking when they are thinking ; but, in pro-
portion as this is the case, their thoughts are bewildered and
imperfect. Hence persons who are detected speaking aloud in |
private, are ashamed of having employed language where it
could not be subservient to its appropriate uses.-. When we |
observe a person’s lips moving during his private thoughts, |
we conclude him to be deficient in presence of mind, and sub-
jected for the moment to a certain degree of hallucination.
Reverie is a common failing of human nature. Even. the
strongest minds.are: subject to it. That species of it which
is called verbal. reverie. is incident to those whose relish for
conversation is accompanied with vanity. It is also extreme- -
ly prevalent among literary men, in consequence of a peculiar
share of their attention: being directed to the meaning and
choice of words. We find a great difference betwixt the va-
lue which an illiterate man of natural good sense and the man |
of letters attach to words. “The former thinks of things with-
out words, and merely employs words from acquired habit
when he has occasion to address others: he is satisfied in this
case when he knows that he is fully understood, and despises the
direct study of words as_an idle occupation... But, with litera+

Wor. VIL PTL 3 E. ry.

398 - OBSERVATIONS ON THE

ry men, thinking of things, and thinking of the signs of things,
-are peculiarly apt to be co-existent. This co-existence, gene-
rating confusion, has probably biassed the estimate which me-
taphysicians have formed of the universal and necessary influ-
ence of language.

It has been said in*proof of the necessity of language even
to the act of thought itself, that there are many mental pro-
cesses which cannot be conducted without the intervention of
signs similar to those of language. Examples of this kind in
the mathematical sciences are considered as occurring in great
abundance. The signs in such examples become indeed pro-
minent and useful objects of thought to the student of science,
but they are perhaps in no greater degree the instruments of
thought than land-marks are the instruments of navigation, or
milestones the instruments of travelling. When we have com-
pleted a mathematical calculation, resulting in a precise and
comprehensive theorem, this result is expressed by a more or
less complicated sign. The sign in its various uses employs
our active thoughts; but we have numerous thoughts about
this sign itself, for which we do not in our private meditations
use any signs. The leading sign, which we in this instance
employ, enables us to refer with facility to our past operations,
so as to secure precision in our further studies; but such
thoughts as mertly serve the purpose of the moment are not
even accompanied with the silent use of speech or of signs.
We may perhaps fiud the same fact illustrated in a different
way, by attending to the state of our thoughts, in so far as lan-
guage is concerned, when we exercise the understanding on a
moral subject. We shall probably be conscious that, when we
obtain a new idea, this often exists for some time in the mind
before we can find an appropriate expression for it, and, after
all, our best expressions are rather regarded as hints for elicit-

ing

THEORY OF LANGUAGE. 399°

ing a similar idea in others, than signs fully fitted to convey
our meaning.. It is in this case that we are most certain:
of having performed an act of understanding. This fact may
convince us that language is not the medium of private
thought.

Another mistaken view seems in some degree to influence:
the speculations of metaphysical writers on language, though
it is not expressly maintained :—That. man is originally prone
to communicate all his thoughts to others, and that language:
is nothing else than the spontaneous catenations of our
thoughts put in words. No analytical inquiry is necessary
to demonstrate the fallacy of such an opinion; but it may be:
useful to keep in mind some facts on the subject, which will
serve to put us on our guard against any unconscious leaning.
to it, in estimating the justness of particular theories of lan-
guage. A person whose conversation consists of mere think-.
ing aloud is always considered as betraying weakness by an:
imprudent deviation from the original purposes with. which
language is employed. We expect a speaker to have some.
other object in view, than merely to gratify a proneness to
communicate his thoughts. Many thoughts which it is reckon-
ed allowable and laudable for him to entertain cannot be ex-
pressed to others, without subjecting him to the charge of im-
pertinence.

There is one fact in the history of man; which is certainly
worthy of more attention than it generally receives, being too:
often overlooked in its relation to some other views with which
we are occasionally occupied,—that thought is of much earlier.
date in the life of the individual than language, Inattention.
to this fact appears to be the reason, that those who have ex-.-
pected to find in etymology a developement of the first prin--

3E2 ciples.

400 ; OBSERVATIONS ON THE

ciples and the earliest history of human thought have not
met with adequate success. The origin of thought and
the origin of language form distinct subjects of inquiry, the
difference betwixt the eras that belong to them: not being
accidental but essential. There is nothing in the general
nature of the thinking faculty of man that implies a prone-
ness to communicate his thoughts to ethers. His inclina-
tion to speak to his neighbour is not the consequence of
the simple existence-of thought, but arises from a particular
kind of thoughts which occupy his mind. His motives for
_ employing any sort of language are to be found in the mu-
tual relations subsisting among the species. “The ideas re-
ceived from inanimate nature might exist in full vigour, and
the sensations of pleasure and pain might be varied and lively,
and yet never lead to the employment of language. Before
language can have existence, a man must perceive that he is
surrounded by other sentient beings ; he must know that some
analogy subsists betwixt their perceptions and his own; he
must be acquainted with the principles of mutual attention and
imitation, which characterise human nature; and, he must
know. that..it-is practicable to influence the thoughts of -others
by means of signs. -Afier possessing all this knowledge, he
must, before bes can use language, feel the influence of some
particular motive. These circumstances not only enter into the
first contrivance of language, but perpetually accompany the
employment of it.

In speaking to our neighbour, we employ a certain power of
which we find ourselves possessed to rouse his thoughts from
a state of inaction, or to direct them to objects dicen from
those which have previously engaged them. ‘The exercise of
this power is properly an IMPERATIVE Act, and the original and
‘most natural expression of it, is in the Imperative mood of the

verb.

THEORY OF LANGUAGE. 401

verb. I may here observe, by the way, that I do not use the
the word Imperative as meaning the exercise of a power im-
plying positive superiority in one individual to another, but as
expressive of the general characteristic circumstance of per-
sonal influence, and including all its forms,—solicitations, for
example, as well as commands. An Imperative is implied
both in the use of Nouns and of Verbs. A grammarian may
call a noun a simple sign of an idea, implying no further move-
ment of the mind ; but he will find, on closer consideration, that
every person, in making use of a noun, expresses some inten-
tion, and that this intention gives to the simplest word the
force of an animated sentence. When we pronounce the
name of an object, we desire the person addressed to,think of
it, and this itself implies an Imperative act along with the par-
ticular idea pointed out.

The tendency of the preceding observations. is to establish
two positions in the theory of grammar, which are connected
with each other, and which differ from the doctrines usually
entertained. The first is, that the object of language instead of
being described as consisting in the communication of our
thoughts, should be made to consist in propucine THOUGHT,
Or iN INFLUENCING THE THOUGHTS OF OTHERS, BY THE MEDIUM
oF worps. The other is that, instead of considering all Lan-
GUAGE aS AFFIRMATIVE, we ought to consider it as originally
IMPERATIVE. |

Those who are averse to think favourably of this doctrine
will, on consideration, find it at least to be less liable to some
exceptions than that to which it is opposed. These exceptions
they may indeed despise as founded in verbal quibbles ; but it
ought to be recollected that, in the doctrine of words, the pre-
cluding of quibbles is a very important object. I hope to shew
that this doctrine will, with the aid of a little illustration,

throw

402 OBSERVATIONS ON THE.

throw some light on the general nature of Language, and
prove materially subservient to the purposes of a. rational ety-
mology.

Imperatives seem to be deprived of their clitirset alin ani-
mation when we attempt to resolve them into affirmations.
Affirmations, on the other hand, will preserve that. interest
which originally belongs to them by being considered as im-
perative directions for regulating the thoughts and volitions of
others.

The etymology of verbs in every language illustrates the
primary importance of Imperatives. The first purpose. for
which a man naturally employs language is to implore the as-
sistance @f his fellow-creatures. The first ideas, therefore, for
which he wishes to have signs are those of locomotion.
Words expressing locomotion are employed for a variety of
purposes; but that purpose for which a man is likely soonest
to call the attention of another to the idea by means of the
oral sign, is to solicit him to perform the motion. For this
reason, the Imperative is in all languages the shortest part of
the Verb. In the English language, it consists in the mere use
of the syllables which distinguish each verb from all regonges
It is in the Imperative that we say, “ walk,”—* run,”—
and “ go.” ‘The other uses of the verb, such as that of descri-
bing our own motions or those of a third person, are subse-
quent to it in the order of etymology, as they are in the or-
der.of nature. In such cases, we find the Verb receiving a
Nominative, a ——— or some et of winnie sign.
For example, “I go,’ —“ thou goest,’—*“ he goes.” Even
when the definitive idea expressed by any verb is introduced as
an Object concerning which an assertion is to be made, an addi-

ional sign is employed besides that which is used for the impera-
tive. The simple act is not called “ walk,”’—* run,”—or “:go ;”
but, “ro walk,’ —“ Torun,” —“ To go;” or “ walk-me,”—“ runn-
ING,

THEORY OF LANGUAGE. 403

ING,—go-1nc. ‘ He likes ro walk,” or, “ he likes walk-1ne :”
“ to walk or walking is conducive to health.” This principle of
etymology is equally conspicuous in the Latin language. In
the imperatives “ ama,” “doce,” “ lege,’ “ audi,” we have
merely the letters essential to each verb, together with
the terminating vowel corresponding to their respective
conjugations. In some imperatives even this vowel is want-
ing, as in’ “die,’ “ duc,” “ fac,” and: “ fer.” Gramma-
rians. call these imperatives irregular, and seem to sup-
pose that, at some period, they have been deprived of the
terminating vowel. Unless we had good proof of this, it
might perhaps be with equal probability supposed that these
words retain a simplicity originally belonging to all impera-
tives. At all events, they illustrate the tendency to brevity i in
this form of the verb. It is not necessary to recur to uncer-
tain points in the antiquities of any language, in order to find
out the principles of etymology. They are exemplified in eve-
ry modern language. They are abundantly displayed in those
cases in which a new language has been formed from materials
surviving that destruction of pre-existing languages which is
naturally occasioned by the competition of several of them for
current use, in the mingling of different tribes. The same ra-
dical principles are even found to operate in the diversities of
provincial dialects, and in the variations produced by the rest-
less spirit of novelty. The imperative of the Latin verb e0,
is as short as can be imagined, as it consists of the single let-
teri. When the definitive idea represented by any verb is
considered as an object concerning which an assertion is to be
made, intimation of this ee Se is given in the Latin
language by the termination “re” added to the imperative.
From the ie pps i a we nega “‘ ama-RE,” “ doce-
“ pe? « lege-re,’ “ audi-re,’ and “i-re.” This termination

seems

404 OBSERVATIONS ON. THE.

seems to be nothing else than the noun “ res” in an inde
clinable form. J signifies “ go;” L-re, “ go-thing;” go con-
sidered. as a thing, or Object of thought. Vult i-re, “ he wills
going, or the thing to go.”

Those inarticulate sounds which express strong sensation,
which are not originally addressed to any hearer, and are ut-
tered even by the deaf and dumb, such as laughing, crying,
and expressions. of surprise, are the. only sounds that precede
Imperatives. They are in the first place.involuntary, and af-
terwards uttered from design. A man desirous of impressing
another with a particular passion first contrives to excite it in
his own mind, and then utters the sound by which it is ex-
pressed. Some sounds bearing a resemblance to these are
conveyed by articulate syllables, and ranked by grammarians
under a head by themselves, to which they give the name of
Interjections.. Mr Tooxe refuses them any place in human
language, because they are common to us with. brutes, and are
in some degree symptoms of the wildness of mental dereliction.
Language, however, must include every sound addressed by
one man to another, from the lowest to the highest state of
mental cultivation. Interjections may be considered as a mix-
ture of involuntary expression with social discourse. In the
use of this part of speech, man is seen.to rise from the charac-
ter of an animal impelled>by passion, to that of a reflecting be-
ing, who discovers intelligence and address in influencing his
fellow-creatures. Interjections, in so far as they partake of the
nature of social discourse, are real imperatives. —

The imperative influence which mankind, by. means: of lan-
guage, exert over the thoughts. of one another, is. subject to a
variety of modifications, which depend not so much on the di-
yersities of their thoughts themselves, as on the different forms
ef the relative situation in which the speaker stands to the per-

son

THEORY OF LANGUAGE. 405

son addressed. It. is by examining these modifications. that we
may expect to make the most successful advances in acquiring
a philosophical knowledge of the parts of speech. ‘They may
be distributed im the following manner :

1. We desire another to perform some voluntary: motion.
This gives rise to Imperatives in their acknowledged form.

2. We direct his attention to objects that are independent of
himself. ‘This gives rise to words that designate External Ob-
jects; and. to words which connect. these with imperatives.
Under this head we shall probably be obliged to rank not only
substantive and adjective nouns, but.-participles, adverbs, pre-
positions, and some conjunctions...

3. We direct him to combine and arrange his ideas in a de-
. finite manner. This gives rise to those parts of speech which |
are: subservient to Affirmation.

Lastly, We desire him to give us information. This gives
rise to Interrogatives.

Perhaps it would be rash to assert. that the different parts of —
speech would be most advantageously treated in the order now
mentioned. It is probable that the analogy subsisting be-
twixt the inflections and uses of the imperative and the indica-
tive of the verb, would render it advisable to. consider them in
‘conjunction. Similar considerations might perhaps justly in-
duce us to give the other parts of speech an arrangement near-
er to that which they receive in our common grammars, We
shall find, however, that when we trace the prevalent etymolo-
gies among éach of those kinds of words which are referred to
different parts of speech, the radical importance of the impera-
tive of the verb every where appears. This fact will be illus-
trated by a few observations on the progress of etymology.

Vor. VIL P. If, 3F | Ae

406 OBSERVATIONS ON THE

As few objects of our knowledge have a natural connection
‘with such sounds as the human voice can imitate, the choice
of the respective oral signs appropriated to the expression
of our different ideas, is for the most part entirely arbitrary.
Hence the origin of the first invented words must have been
regulated by such slight and momentary views, that their his-
tory was lost before they received an established application.
Words strictly original, however, are probably few. The
greater part are derived from others previously existing, which
receive such modifications as are sufficient to distinguish the
various shades of their application. In coining new words,
mankind have always a wish to employ materials to which
some sort of meaning was previously attached.

Under the operation of this law, there is one very extensive:
feature of etymology, which we are obliged to Mr Tooxe for
pointing out more fully than was done by his predecessors, and
which he seems inclined to regard as universal,—that nouns, or
the names of objects, are derived from Verbs. To this we
may subjoin, that the verbs from which they are derived signi-
fy some sort of action, and, as has been shown, exist in the
simplest form in the Imperative.

This position is illustrated in the Diversions of Purley, by a
very copious induction. Mr Tooxsr shows that many English
nouns, which we had been in the habit of considering as origi-
nal words, are derived from verbs. A “ passage” receives its
name from the verb “ pass ;” a “ gate” from the verb “ go ;” a
“ road” from the verb “ ride.” “ Spot,” “ spout,” and “ spite,”
are from the verb “ spit.” “ Snout” and “ snot” are things
“ snited.’” ‘* Head,’ from the verb “ heave,’ means some-
thing “ heaved” or elevated above the neighbouring objects to
which it is referred. ‘“ Heaven,” from the same verb, means
the same thing. A “ flood” is something that has “ flowed.”
“ Bread” receives its name from the verb to “ bray” or

“ bruise,”

THEORY OF LANGUAGE. 407:

“ bruise,’ because it is made of grain’ which, among other~
operations, has undergone that of being “ brayed.” A “ joint’
is something “ join’d.” The word “ gift” is the same’ with
“ oiv’d” or “ given:” “ thrift” is from.“ thrive,” “ drift” from
“ drive,” “ weft” from “ weave.” The “ haft” of a tool is
the part “hay’d.” The “ hilt” of a sword, the part “ held.”
A “ clock” is an instrument that “ clicks.” “ Doom” means
“ deemed,” from the Saxon verb “ daman,” to “ deem” or
“judge.” “ Brood,” “ breed,” brat,’ mean something che-.
‘rished, from “ bredan” to “ cherish.” ‘“ Hand” and “ hint’
are from “ hentan,” to “ take hold of.” “ Fang” and “ finger”
from “ fingan” to “ take.” “ Truth” comes from the verb
“true,” because it is that which a man “ tru-eth” or “ belie-
“veth.” “ Wealth” is that which “ weal-eth;” “ growth”
that which “ grow-eth;” “ birth” that which “ bear-eth ;”
“ warmth,” that which.“ warm-eth ;” “earth” that which a man.
“ ear-eth” or “ plougheth.” Nouns derived from Latin verbs
are more familiar in their etymology, as, an “ act,” “ aliquid
“ act-um,” a “ debt,” “ aliquid debit-um ;” “ rent,” “ aliquid
“ rendit-um ;” “ tribute,” “ aliquid tribut-um ;” “ expense,”
“ aliquid expens-um ;” “ merit,” “ aliquid merit-um ;” “ ac.
“ cent,” “ aliquid accent-um ;” “ fruit,” “ aliquid’ fruit-um ;”
“ fate,” “ aliquid fat-um.” Some words of French derivation.
are obviously formed on the same principle, as “ alley,” from
the — “aller” to go; “ view,” something seen,” from.
“ vu,” the ea participle of “ voir ;” '“ destiny,” “ ie
** chose destinée.”

As Mr Tooxe seems inclined to maintain that a// nouns are
formed from verbs, and as the induction which he has brought
forward is more extensive than his readers were prepared to an-
ticipate, some have been struck with an apprehension that this
doctrine would prove injurious to some of the most satisfacto-.

408 OBSERVATIONS ON THE

ry conclusions that prevail among mankind. Its tendency has.
appeared to be to shake our belief in the existence of a mate-
rial world. Verbs have been considered as mere expressions
of certain temporary modifications to which matter is liable,
and therefore a subordinate class of words compared to the
names of substantial beings. It has been thought a degrada-
tion of the truths received by the testimony of our senses, to
suppose that permanent objects should derive their names from
words of so fugitive a character as verbs, which represent mere
events, or phenomena that disappear the moment after they
are presented. This apprehension will vanish if we attend to
the distinction betwixt the early history of thought and the
early history of language. Our first ideas are acquired, and
extensively combined, long before we express them. The first
words of which language consists represent, in the form of
compendious signs, assemblages of ideas, or features of these
assemblages, mutually dridenatd among men. ‘The etymo-
logy of each derivative word depends on the motives which di-
rect us to select those definite assemblages to which it will be
useful to assign names. Accordingly, we find that the volun-
tary motions ae mankind, which have already been considered
as the earliest objects that suggest the use of language, and
which are first used in the fom Mae Imperatives, have a predo-
minant influence in regulating the interest which we take in
directing the attention of those around us to other objects, and
in contriving names to represent them. Let us take for an
example the word “ road.” The surface of the earth presents
us with one continued series of colours and tangibilities which
we call the qualities of matter. We wish to direct the atten-
tion of another to a part of this scene, which has the form of a

lengthened stripe, differing somewhat in appearance from the

adjoining parts; and we sacar that the difference which we
observe

’ i toi ee

THEORY OF LANGUAGE. 409

observe is produced by the action of travelling, or is made for
promoting the convenience of this voluntary motion. The ma-
terials of which it is composed do not radically differ from
those which compose the parts in its immediate vicinity, and
the same sensations are communicated by the ultimate parti-
cles of each. But the characteristic mode of assemblage which
they exhibit, suggests the idea of the cause. which has produ-
ced, it, or the purpose to which it is subservient. Hence we
derive its name from the action of travelling or riding. This
is the origin of the word “ road.” It signifies a place which
has been “ rode” upon. On the same principle, an uninhabi-
ted country is called a “ desert,” because it is “ desert-um,” a
place forsaken or avoided by men. A cultivated spot is called
a “field” or “ felde,’ from the past participle of the verb
“ fell,” intimating that the trees which are supposed to have
once covered its surface are cut down. In short, the particular
interest which an association with the motions of mankind
gives to the assemblages which our words denote fully accounts
for the facts adduced by Mr Tooxe in proof of the prevalence
of this mode of derivation among Nouns, and at the same time
illustrates the various positions which have been advanced in
the present paper. This law, while it throws light on some of
the operations of the human mind in imposing names on ex-
“ternal objects, neither throws any dubiety on the existence of
an external world, nor prevents us from admitting that the
materials of which it is composed possess an importance in-
dependent both of human action and of human thought.
_ While MrTooxe has been blamed for leading his readers to the
species of scepticism now alluded to, it has also been his fate
to be accused of employing grammatical analysis in the sup-
port of a doctrine diametrically opposite, that of Materialism.
He has asserted that every word expresses an “ object,” by

which

410 OBSERVATIONS ON THE

which he seems to mean an external object ; and thus it has’
been supposed, that no room was left in his theory of Language
for expressing the important phenomena of Mind. From this
it has appeared to be an inference, though certainly a very il-
logical one, that mental operations are merely the result of
the varied motions of matter. But it is probable that those
facts in the formation of languages advanced by Mr Tooxe
which appear to have- this. last tendency would, if enquired
into, throw a further light on the progress of the human mind
as displayed in giving origin to various oral signs, without
at all influencing the question of materialism. If a full view
of the theory of language were exhibited, these facts would
come under consideration, and it would be necessary to attempt
an explanation of them. They are not, however, farther
connected with the observations contained in this paper than
as belonging in general to the theory of language, although
now alluded to from being suggested in consequence of the
contradictory sentiments. which have been ascribed to the au-.
thor now mentioned. |

The author of the present memoir indulges a hope that some.
valuable instruction will ere long be derived either from the
criticisms of the learned on the doctrines which he has here:
ventured to offer to their attention, or from exertions other-
wise made to cultivate a subject which undoubtedly lies open:
to much improvement.

XLV...

XIV. On the Diffusion of Heat at the Surface of the Earth.
By Joun Murray, M. D. F.R.S. En.

(Read 2d May 1814.)

N argument which I had stated against the Huttonian
A Theory of the Earth, in so far as it relates to the opera-
tion of a central heat, was honoured some time ago with a re-
ply by a distinguished Member of the Society. Respect for
the opinion of Mr Piayrair led me to consider attentively the
reasoning he employed ; and still feeling some confidence in the
grounds on which the original argument rests, I propose to of-
fer a few observations with regard to it. The question farther
involves the consideration of the mode in which heat is distri-
buted at the surface of the globe. This, when minutely inves-
tigated, presents a very perfect arrangement, by which the
escape of caloric is prevented, while its equal distribution is
more effectually attained ; and the subject, under this point of
view, may have some interest, independent of its relation to any
controversial discussion.

- The argument which I had advanced i is, That if a heat’ exist
in the interior part of the earth, operating for an indefinite pe-
riod, as is assumed in the Huttonian Theory, it cannot for such
a period remain, locally accumulated. It must diffuse itself

through

412 ON THE DIFFUSION OF HEAT

through the entire mass, and become at length equal, or near=
ly so, over the whole. An equilibrium of temperature must
therefore be established, incompatible with that system of in-
definitely renewed operations which is represented as the great
excellence of the system. This has always appeared to me
conclusive ; and an argument such as this, derived 4 priori, and
directed to the first principles of a geelogical theory, if sue-
cessful, is of greater weight than arguments derived from its

adaptation to natural phenomena, which, even when they ap-.

pear to be just, amount only to probability, and, from our im-

perfect knowledge of the relations of the mineral kingdom,

leave often some degree of uncertainty *.

To obviate this argument, the following reasoning has been
employed by Mr Prayrarr. The diffusion of temperature, he
remarks, is a consequence of the tendency of heat. to pass from
bodies where the temperature is higher to those where it i8
lower. It is not, therefore, a necessary result, but is only con-

tingent,

* T ought to remark, that this view of the constant existence of a central heat
is not considered by all the defenders of Dr Hutron’s system, as a necessary
part of it, nor do they even regard it as a position which he himself maintained.
They suppose the existence’ only of interior local heat, which may cease for a
time, and be again renewed ; and to this hypothesis the above argument does not
so strictly apply. I must only add, that if even this view of the subject be
adopted, much of the: difficulty will stilk remain in its original’ force; it be-
comes liable, too, if I mistake not, to other objections peculiar :to itself, equally
important ;, and by adopting it, much of the beauty and unity of the system are
lost. ‘Ehese. seem to me to require the assumption of a central heat, or general
reservoir of ‘heat capable of extending its action to every part of the circumfer-
ence, always existing, though not equally active in its apparent effects. It is to
this view of the subject, consistent, I believe, with the original statement of
the theory by Dr Hurroy, that the argument applies. It is this which Mr
Prayratr admits, and on the admission of which, indeed, his reasoning is
founded; and, strictly speaking, it is to his reasoning only that the. observa-
tions in this paper are directed.

AT THE EARTH'S SURFACE: 413

tingent, requiring the presence of another condition, which
may be wanting, and actually is wanting, in many instances ;—
this is, that the quantity of heat in the system should be given,
and should not admit of continual increase from one quarter,
nor diminution from another. When such increase and dimi-
nution take place, no such equilibrium can be attained. In
proof of this, he mentions the fact, that a bar of: iron thrust
into the fire, though red-hot at one extremity, will not become
so at the other in any length of time, but each part of it will
have a fixed temperature, lower as it is farther from the fire,
but remaining invariable while the condition of the fire, and
of the surrounding medium, continues the same. He illustrates
it also more fully by the following example: Let A, B, C, D,
&c. be a series of contiguous bodies, or let them be parts of
the same body ; and let us suppose that A receives from some
cause, into the nature of which we are not here to inquire, a
constant and uniform supply of heat. - It is plain that heat will
flow continually from A to B, from B to C, &c.; and in order
that this may take place, A must be hotter than B, B than C,
and so on; so that no uniform distribution of heat can ever
take place. ‘The state to which the system will tend, and at
which, after a certain time, it must arrive, is one in which the
momentary increase of the heat of each body is just equal to
its momentary decrease, so that the temperature of each indi-
vidual body becomes fixed, all these temperatures together
forming a series decreasing from A downwards. This is then
applied to the argument in the following manner : “ If heat be
communicated to a solid mass, like the Earth, from some
source or reservoir in its interior, it must go off from the
centre on all sides towards the circumference. On arriving at
the circumference, if it were hindered from proceeding farther,
and if space or vacuity presented to-heat an impenetrable bar-

Von. VII. P. II. 3G rier,

414 ON THE DIFFUSION OF HEAT

rier, then an:accumulation of it at the surface, and at last a
uniform distribution of it through the whole mass, would ine-
vitably be the consequence. But if heat may be lost and dis-
sipated in the boundless fields of vacuity, or of ether, which
surround the earth, no ‘such equilibrium can be established.
‘The temperature of the earth will then continue to augment,
only till the heat which issues from it every moment into the
surrounding medium, become equal to the increase which it
receives: every moment from the supposed central reservoir.
When this happens, the temperature at the superficies can un-
dergo no farther, change, and a similar effect must take place
with respect to every one of the spherical and concentric strata
into which we may conceive the solid mass of the globe to be
divided.. Each of these must in time come to a temperature
at which it will give out as much heat to the contiguous stra-
tum on the outside, as it receives from the contiguous stratum
on the inside, and when this happens, its temperature will re-

main invariable *.”

The principle on which this reasoning rests will not be dis-
puted. Admitting it therefore, my objects in attempting to
support the original argument will be to shew, jirst, That such
a discharge of heat from the surface of the earth as is here sup-
posed does not take place; and, secondly, That if it did, this
would be as subversive of the system, as if the heat were
retained.

There are two modes in which caloric may be supposed to
be conveyed from the surface of the earth ; one is by radiation,
the other by slow communication by the medium of the elas-
tic fluid, which surrounds it. Each of these may be briefly
considered. ba

| . The
* Transactions of the Society, vol. vi. p. 356..

AT THE EARTH'S SURFACE. 415

The great expansibility and mobility of an elastic fluid, such
as the atmosphere, give rise to a peculiarity with regard to
the communication of temperature through it. . Its: proper
conducting power appears to be inconsiderable,. but; whatever
it may be, it is principally by the motion of its parts that heat
is diffused through its mass. When the temperature of a
lower portion of such a fluid is raised it ascends rapidly; a
fresh portion comes in contact with the surface communicating
heat ; and by this successive application and retrocession of the
air, and this movement of the heated portion, rather than by
the direct communication of caloric from one part. to another,
the temperature of the whole is raised. It is in this manner
that heat is diffused from the earth into the atmosphere. The
air incumbent on any part of the surface communicating heat,
is, by the elevation of its temperature, rarified, whence an as-
cending current is formed ; and the common opinion with re-
gard to this is, that it ‘carries the excess of heat to the higher
regions of the atmosphere, and may. allow it to be diffused in-
to the interplanetary space. It is on the asqupaption of this
that the heat must be supposed, in Mr Pruayrare’s ar ‘gument,
to be discharged from the earth, so far-at least as it is convey-
ed, from the surface by the surrounding elastic medium. The
just view of the operation of the atmosphere in diffusing heat,
is however more complicated; other conditions connected
with it are to be taken into account, and lead, I believe, to a
very different result.

The air heated at any part of the eainthis saiceck may, as it
ascends, impart, especially at first, a portion of heat to. the air
with which it comes in contact. But as it rises, becoming sub-
ject to less pressure, it expands ; by this its capacity for heat is
augmented, and its temperature, therefore, falls proportionally.
As it recedes from the surface, with its temperature thus con-

3G 2 stantly

416 ON THE DIFFUSION OF HEAT

stantly falling, from its increasing capacity, its tendency to part
with heat is always becoming less; and as it must continue to:
rise in the atmosphere until it attain an equilibrium of tempe-
rature with the air around, any tendency to communicate heat
to that air must at length cease. If it retained its high tempe-
rature, or if it were to lose this gradually only from the communi-
cation of its heat, it might be conceived to-convey caloric on-
wards; but its capacity for caloric increasing from its rarefac-
tion as it ascends, it is enabled to retain the excess of heat it
had received, without having a corresponding elevation of
temperature. It is only when it returns towards the surface,
in consequence of that circulation which the constant ascent of
portions of heated air establishes in the atmosphere, that this
is evolved. As it descends, it becomes progressively subject
to greater pressure, its capacity gradually diminishes ; and con-
tinuing to do so as it falls, it gives out in the same gradual
manner the excess of heat which it contains. Thus, for every
portion of heat conveyed by the ascent of a stratum of heated
air from any part of the circumference of the- globe, a corre-
sponding portion of heat is given out by a descending stratum
at some other part; and as this communication of heat from
the atmosphere will happen principally at the colder parts. of
the earth’s surface, both as the descent of the air will be there
greatest, and the disposition to receive heat also greatest, the
whole forms an admirable arrangement to counteract local ine-
qualities of temperature, to diffuse heat equally over the globe,
and to prevent any dissipation of it beyond the sphere of the
atmosphere. .

It is thus, I conceive, demonstrated, that by the principal
mode in which heat is propagated through the atmosphere,—
that, by the motion of the heated portion of air, it can only
be withdrawn to comparatively a short distance from the sur-

face:

AT THE EARTH’S SURFACE. 417

face of the earth, and that there is a constant return of it. By
direct communication its conveyance must be equally limited;
the conducting power of an aeriform body is extremely imper-
fect, and there is every reason to believe becomes less as the
fluid becomes more rare; and in the higher regions of the at-
mosphere, the subtilty of the medium is so great, that beyond
a certain height it cannot be supposed to be the vehicle of the
conveyance of heat, far less that it can convey it into the
boundless fields of vacuity. _

But, farther, were the conducting power of the most: perfect
kind, no effect could arise from it in the conveyance of caloric
beyond a certain-height. The communication of heat from
one part of a mass of matter to another, or from one body to
another, depends, as Mr Prayrarr justly observes, on differ-
ence of temperature, and if there is no difference, there will
be no such communication. Now, a little reflection will shew,
that this completely limits the diffusion of heat through an
elastic fluid, receiving it under such conditions as our atmo-
sphere. The air heated at. the surface expanding as it rises,
but at the same time, from this expansion falling in tempera-
ture, must come at length to be in equilibrium, both in densi-
ty and in temperature, with air at a certain height; its farther
ascent will then cease, and its temperature being the same
with that of the air around it, it will yield none of its heat.
It is only in its descent, as a fresh portion of air rises, that it
will evolve caloric, and it-will continue uniformly to do so, as |
it returns to the surface of the earth.

We thus trace a curious provision to prevent any discharge
of heat by the atmosphere into the interplanetary space; the
excess at particular regions is only withdrawn, is more equally
distributed over the Seiaie: but is alvinadtclt communicated

to the earth ; and there is no other apparent arrangement by
which:

Als ON THE DIFFUSION OF HEAT

which this could have been attained, than by an atmosphere
constituted 'as:ours is,;~-expanding as it is heated, and falling in
temperature from. augmentation of capacity as it expands... To
admit of an unlimited conveyance ef heat, a solid mass, how-
ever subtle, would have been required, or an atmosphere the
capacity of which for caloric should not increase with its rare-
faction.

The passage - heat. is thus from the circumference towards
the centre of the globe, instead of the opposite direction, and
it is prevented from accumulating at the surface ers by being
conveyed into the. mass of earth.

‘These! conclusions. may. be applied to the present argument.
If the view Ihave stated be just, we have demonstration that
the.atmosphere conveys no heat into unlimited space ; our pla-
net, in relation to the discharge of caloric from it, is bounded
as it were by a.wall of non-conducting matter, and no arrange-
ment:can be imagined more perfect, by which the heat belong-
ing to it could be:confined. If the heat from the centre, Mr
Puayrare observes, on arriving at the circumference, were pre-
vented from proceeding. farther, and if space or vacuity pre-
sented to heat an impenetrable barrier, then an accumulation
of it at the surface, and at last a uniform distribution of it
‘through the whole mass, would inevitably be the consequence.
It appears that the atmosphere does present such a barrier, and
the consequence, therefore, necessarily follows *.

w This

* If the sphere from the centre of which heat is supposed to be diffused, be
‘not exposed to an unequal external source-of heat, the heat will be communica-
ted equally at its circumference ‘to the incumbent atmosphere, and produce as-
cent and descent of the air, with little of that circulation of it from one part to
another, which is the consequence of inequality of temperature at the surface of
the solid. But still the same changes of capacity for heat will accompany the
ascent

— 63.

“sities ~
is
r i gk a

— i a

oo

AT THE EARTH’S SURFACE. 419:

This is true, at least, so far as relates to any power of the at-
mosphere to convey heat. There. is still to be considered,
however, another mode in which caloric may. be supposed to
be discharged from our planet,—that by radiation. , Rays pos-
sessed of heating power are thrown off from a body at a high
temperature, and by the discharge of these. its. temperature is
reduced. But various considerations shew, that this would be
a very inadequate source of the escape of heat from the inte-
rior part of the earth.

Thus the radiation of caloric is ee eaea lee adali except iene
a body which is heated; and the quantity radiated increases
as the temperature rises in a much higher ratio.than the in-
crease of temperature itself. At low temperatures, therefore, ©
it must be extremely small. At 100° it is scarcely apparent,
from experiment ; and at 50° is not sensible. Not only, too,
does the quantity diminish rapidly with the temperature, but
the projectile force of the rays emitted becomes. less, so that
those which are discharged at low temperatures, are incapable of
penetrating media such as glass, which those at high. tempera- -
tures penetrate with facility. And as even the latter are, to a
certain extent, intercepted by the atmospheric air, the former
must be more completely arrested. At 50°, therefore, the me-
dium temperature of the globe, and stub prevails over so
large a portion of its surface, we have no reason to believe -
that a discharge of caloric by radiation, into remote space,
can take place to any extent.

At

ascent,.and descent of the aerial mass, and the principal effect will be, to accumu-
late temperature at the surface. The condition is one, however, which, need not
to be taken into account, as it is one which has never existed with regard to our
planet ; and the argument remains as is stated above, while there is inequality in «
the distribution of heat over the circumference of the globe.

490 ON THE DIFFUSION OF HEAT

At the parts of the surface of the earth which are at still
lower temperatures, and at those where intense cold prevails,
the supposition of any radiation is of course still more preclu-
ded, and the negative even may be proved. When a solid bo-
dy, and the surrounding elastic medium, are at the same tem-
perature, there seems to be no discharge of radiant heat from
the former ; and still more when the temperature of the solid
is lower than that of the elastic medium, ‘(and this is usually
the case in colder regions), it is rather disposed to absorb than —
to emit caloric by radiation. The resistance, too, opposed by
the atmosphere to the discharge of rays having the weak pro-
jectile force which those emitted at such a low temperature
must have, would in a great measure prevent their escape, if
the power to radiate did actually exist.

At the hotter parts of the earth’s surface there may be some
emission of caloric by radiation, but it is not difficult to shew,
that the quantity of this cannot be equal to the quantity com-
municated by the solar rays; for of the heat derived from the
latter source, a portion is absorbed by the earth, and conveyed
to the interior, as is apparent from the decreasing tempera-
ture, as we recede from the surface to a certain depth; and
another portion is carried off by the ascending current of
heated air, and conveyed to colder regions, where it is also
absorbed. |

Thus, even from ‘those parts of the surface of the earth
where the circumstances are those most favourable to radia-
tion, the quantity radiated cannot be equal to the quantity re-
ceived by the solar rays. Over the whole surface, the differ-
ence must be still greater, and instead of the conclusion, that
this planet discharges an excess of heat by radiation, there.is
every reason to draw the opposite conclusion,—that part of the
heat which it receives from the sun is retained.

The

AT THE EARTH'S SURFACE. 421

The only reason, at least, that would lead to hesitation in
admitting this last-inference, is a hypothetical one,—that it is
inconsistent with that perfect arrangement; which we are dis-
posed to believe exists among all the heavenly bodies, whence
the stability of the entire system is maintained, and whence,
therefore, in relation to any communication of caloric among ~
them, the quantity radiated by each will, on the whole, be
equal to what it receives. This, whether we restrict the view
to the different parts of our solar system, or extend it even to
the universe, is no doubt the conclusion which the imagina-
tion is naturally disposed to embrace, though it may not be
supported on any decisive evidence, or may even be in some
measure apparently in opposition to the fact. But to suppose
that this planet discharges more caloric than it receives, would
be not only in opposition to evidence, but in opposition to
‘the very principle which alone leads to the admission
that the quantity discharged may be equal to the quantity re-
ceived.

Concluding, then, as it appears to me, may be strictly infer-
red from the preceding reasoning, that our earth does not dis-
charge caloric from its surface into the regions of space, or at
least does not discharge more than it receives from the other
heavenly bodies, if it discharge even this, the argument recurs,
I believe, in its original form, as. sufficiently established, That
if an interior heat exist, it must be diffused through the sub-
stance of the earth, and an equilibrium of temperature be at —
length established, incompatible with those operations ascri-
bed to its action in the Huttonian Theory. ;

- But farther, though the heat were not retained,—though it
were granted that it is propagated into the regions of space,
this does not render the argument I have urged less con-
clusive. The strength of that argument lies in the circumstance,. -
of the diffusion of heat from the interior, not in the accu-

Vor. VIL. Fa. - 3H mulation

422 ON THE DIFFUSION OF HEAT

mulation of that heat at the surface. The latter is a con-
tingent event, which may or may not happen, without being of
essential importance in the conclusion to be drawn. The
former is a necessary result, which must prove subversive of
the arrangement, the assumption of which constitutes the lead-
ing principle of Dr Hurron’s System.

Mr Puayrar, accordingly, in the general case which he
takes for the illustration of his argument, assumes @ constant
supply of heat at the centre, as well as a constant escape of it
from the circumference. But in applying the argument, where
is the proof of such a supply of heat at the centre of the
earth ? It can scarcely be necessary to remark, that none is
attempted to be given. And were it allowable to make an
assumption, without evidence, merely to obviate an argument,
the force of which cannot otherwise be avoided, no hypothesis,

even the most extravagant, could ever be overturned. Heat’

_ cannot originate in nothing ; and if we assume its constant dis-
charge from the circumference of this planet, what cause is it
possible to assign for its constant supply from the interior ?
Admit even its existence in any degree of intensity, still
it is obvious, that it must be in limited quantity. If we
speak of a spring of heat, as conveying the idea of an unli-
mited supply, we deceive ourselves by the use of a term to
which no definite signification can be affixed, but what is sub-
versive of the reasoning it is designed to support. A source
or spring means nothing more than a hidden reservoir, con-
nected with external supplies. There can be no reservoir of
heat in the centre of the earth, which, without being recruited
by constant supply, shall continue to furnish it, to be dischar-
ged from the circumference through indefinite time into unli-
mited space. And it is not possible to imagine any circula-
tion by which it shall be restored. ~

It

~ gp ae

AT THE EARTH'S SURFACE. 493

It is, therefore, I conceive, of little importance m the
discussion, whether the heat supposed to be conveyed from
the centre to the circumference is accumulated there, or is dis-
charged into the regions of space. Its propagation to the
surface must be subversive of its accumulation in the interior.
Either the diffusion alone, therefore, or the diffusion attended
with the final result of equilibrium of temperature, is sufficient
for the refutation of the hypothesis. Both I conceive are esta-
blished. And I would still regard the argument in the light in
which I first advanced it, as a demonstration of the fallacy of
the leading principle of the Huttonian System, which as-
sumes the existence of an internal heat operating at renewed
periods for indefinite time.

There are some other points of view under which the sub-
ject may be considered, in which the difficulties attending the
assumption of an internal heat, when connected with the law
which Mr Prayrair has illustrated, appear in a very strong
light.

It has always been found difficult to give any account of the
origin of the supposed internal heat, to the operation of which
the consolidation of minerals, and the elevation of the habitable
land from the bed of the ocean, have been ascribed. If the
view be restricted to the production even of one world, such
an intensity and continuance of heat are necessary for this
single effect, that no adequate cause can be even hypotheti-
cally assigned for it. If it be extended to the successive pro-
duction of three or four worlds, each embracing a period be-
tween its formation and destruction in which millions of years
must elapse,—an event which, according to the theory, is not
only possible, but has actually occurred,—the heat required is
altogether beyond what the imagination can conceive. But if
in addition to this, caloric is also diffused from the interior,

3H 2 | and

“94 °° ON: THE DIFFUSION OF HEAT

and discharged from the circumference of the globe into unli-
mited space, we are lost in the magnitude of the result, and
are unable to acquire a just conception of the force of the ar-
gument, from the impossibility of contemplating clearly the
difficulty in all its extent.

The difficulty, from the intensity of the heat which must be
assumed to exist, is not less great than that from its continu-
ance and waste. It is sufficiently apparent, when we consider
that the highest mountains of the globe run in extensive
chains, and are so connected, that they must have been form-
ed at one time, and that they are composed of materials which
a very intense heat does not fuse. But this is nothing com-
pared with the statement which must be made, in consequence
of the law, that the internal temperature is a decreasing one
from the interior to the circumference of the globe.

If we can discover the rate of this decrease, by knowing the
temperature which exists at two distant points, we may of
course form some calculation of the intensity of the heat which
exists at the commencement of the series. Now this we have
the means of determining with considerable precision. At the
bottom of the sea, or within a short distance from it, the heat
from the interior must be at a degree of intensity sufficient to
produce mineral fusion and consolidation from the disintegra-
ted materials of a former land, which may be estimated from
our knowledge of the fusibility of these bodies. It is propa-
gated from this onwards, with such a decrease that at the sur-
face, there is no sensible high temperature. Its diffusion from
the central regions to the bottom of the sea must of course have
been at a similar rate of diminution. If we were to calculate
the rate of progression, and compare it with the distances in
the two portions of space,—that from the central region to the
bottom of the sea, and that from the bottom of the sea to the

surface

AT- THE EARTH'S SURFACE. 425

surface of the land, we shall find an intensity of heat in the in-
terior, compared with which the heat necessary to melt moun-
tains of quartz, formerly supposed to present so great a diffi-
culty, is a mere atom in the scale, scarcely affording even a.
point of comparison.

Some idea may be formed of this, by recurring to the illu-
stration of the iron bar, with a decreasing temperature, ma-
king the most liberal allowance in favour of the Huttonian
hypothesis, with regard to the respective portions of space.
Thus the bar, being one thousand inches in length, if its tem-
perature at the one extremity be 50°, and if within five inches
of this it is at a white heat, then the heat increasing at the »
same rate, through. every succeeding five inches, what must
be. its intensity at the other extremity? No effort of the
imagination can form the most remote conception of it, nor
can any argument be wanting to prove, that no such heat can .
exist in the interior of the earth. .

If to avoid the difficulty, a less rapid decrement of tempera-
ture be. supposed, then, from a heat of that intensity which
must be assumed to exist at the bottom of the ocean, to pro-
duce the-effects ascribed to it, the decrease in. the short space
between that’ and the surface. cannot. be such as to bring the
temperature within that which is at all compatible with the
established economy of nature. ‘The ‘difficulty is, therefore,
insurmountable; it must occur on the one hand or on the
other; and it is not merely connected with Mr Prayrarr’s
argument, but as that argument is founded on a law perfectly
just with regard to the diffusion of temperature, it is.a difficul- .
ty which necessarily follows from the assumption of a central
heat, or of any internal heat such as that which must be assu- -
med in the. Huttonian Theory,—a heat which is to operate a-
round the whole circumference of the globe, continue its opera- .
tions for such immense periods, and renew it for indefinite time.

Leaving -

-496 ON THE DIFFUSION OF HEAT

Leaving the consideration of this subject, in so far as it is
connected with the argument on the Huttonian Theory, | may
add a few observations of a more general nature, which the
preceding reasoning suggests with regard to the temperature
of the globe, and its relation to solar heat. From the nature
of the agency of the atmosphere in diffusing heat, the conclu-
sions seem to me almost necessarily to follow,—that there is
a tendency to equalization of temperature over the whole sur-
face of the earth,—that this continues to operate in such a
manner, that in the progress of time the difference at different
parts must become less than what existed at a preceding pe-
riod; and that, ultimately, a temperature nearly uniform shall
be established over the whole.

At the hotter parts of the earth’s surface, the temperature
cannot increase, or must increase very slowly, and to no great
extent ; for if it were to rise higher, the ascent of heated air
from it, and the transfer of this to the colder parts of the sur-
face, would only become more rapid. But the temperature at
the colder regions may rise higher; for the direct ascent of
heated air is there less abundant, and what recedes in a lateral
direction, does so, deprived of caloric, which it has yielded to
the earth. Whatever discharge of caloric, too, may take place
by radiation, must be principally from the hotter parts of the
surface ; from the colder it must be much less considerable,
for the quantity radiated is less as the temperature is low: it
increases, too, at a higher ratio than the increase of tempera-
ture ; and hence, if increased radiation from increased tempe-
rature, did take place at both, being greater at the former than

at

AT THE EARTH’S SURFACE. - 427°

at the latter, its effects would be more considerable in retard-
ing a farther augmentation of temperature. Thus it appears, |
that the causes counteracting rise of temperature at the sur-.
face of the globe, act most powerfully at those parts where it

is high, and any progressive rise, therefore, must be principal-

ly at those where it is low. |

The effect of this arrangement may be most obvious, per-
haps, from comparing the two extremes. At the equator, the -
ascending current of warm air, carrying off heat, is constant
or nearly so; towards the poles, the descending current im-
parting heat, must be equally constant. The heat directly
communicated at the former by the solar rays, and the heat
communicated at the latter by the current of warm air, will
both be in part conveyed through the solid mass towards the .
interior ; but this will always be with a decreasing temperature -
as it proceeds,—that is to say, the first: or exterior. layer will be -
at a higher temperature than the second, the second than the
third, and the accumulation, therefore, will be at the surface,
to a certain extent. At the poles this may continue to pro- -
ceed, because heat is there communicated without an equal ab- .
straction. But at the equator it will remain stationary, or
nearly so, as no increase can take place without the abstrac- .
tion both by the atmosphere and by radiation becoming pro- -
portionally greater. .

This is aided by another effect, that with regard to the dif.
fusion of heat: through. the solid mass itself. This diffusion
from the surface proceeds in part towards the centre, or each .
layer, as the surface is receded from, receives a portion of heat
from the exterior one, and this continues onwards, though with .
a gradual diminution. But there must be at the same time a
diffusion more nearly horizontal, proceeding through these -

layers

498 ON THE DIFFUSION OF HEAT

layers from the equator towards the poles, while there can be
none in the opposite direction to counteract this effect.

The ocean, too, serves to convey a considerable portion of
heat from the warmer to the colder regions of the earth, by
the movement of currents, somewhat similar te those which
exist in the atmosphere, and the course of which it is even pos-
sible to trace. |

Thus, by these various arranyements, whatever -excess of
heat may be received by this planet from the sun, and retain-
ed at the surface, will be permanently accumulated towards
the poles, and the temperature there will increase. In all the
portions of the intermediate space, between the poles and the
equator, the same law will operate, though with decreasing
force ; and over the whole surface, there is a tendency to equa-
lity of temperature, which, however slow the progression to it
may be, must, as the result of general causes constant in their
operation, be finally established.

The speculations, then, on which some have dwelt,—that
the northern parts of our globe have suffered a gradual refii-
geration, and which Bartty, in particular, applied to the fan-
ciful system which he supported with so much ingenuity,—
that civilization and science have descended from the eleva-
ted regions of the north of Asia,—have probably no foundation.
It is always interesting to trace the succession of opinions
which mark the progress of knowledge, and to observe how far
what at one period is considered as established, is at another
rendered doubtful, or proved to be false. The refrigeration of
the globe from the loss of its interior heat, is a fact, says the
author just referred to, of which there can be no doubt; and .
this refrigeration, he adds, must have been principally towards “
the poles, partly from the flattening of the sphere there, in.
consequence of which the heat from the centre must escape

BAe sooner

«~

AT THE EARTH’S SURFACE. 429

sooner, but still more from the unequal action of the solar
rays, which is more intense towards the equator. Hence the
countries round the poles must have been the first that were
habitable, and this gradual cooling has caused the same tem-
perature to proceed successively over all the regions of the
globe *. . Not only are these conclusions unfounded, but the
changes which have occurred are probably the very reverse. No
heat can escape from this planet, but in consequence of a high
temperature being kept up at its surface by the communica-
tion of heat from an external source. Until this be attained, it
must retain the heat it receives from the sun; and this must
accumulate principally towards the poles.

That the temperature at the surface has risen above the ori-
ginal temperature of the earth, may be inferred not only from
the consideration, that solar heat has been communicated to it,
which could not be discharged until a certain elevated tempe-
rature were attained, but also from this, that there is no natu-
ral operation actually generating cold; there is only the pro-
duction of heat ; and cold prevails where this is less powerful,
or is counteracted. To account, therefore, for the low tempe-
rature at the colder regions of the earth, only two suppositions
can be advanced. Either the original temperature must have
been as low as this, or lower, and have been raised higher,
where it is actually superior, by the reception of the sun’s rays:
Or it must be assumed, with Burron and Barry, that heat
can escape from this planet to an indefinite extent, and that it
is in a state of progressive refrigeration, the effects of which
are prevented from being apparent at the equatorial regions
by the direct communication of solar heat, but towards the po-
lar circles are evident, as not being counteracted by the same

Vor. VIL. P. I. 3H cause.

* Lettres sur l’Origine des Sciences, p. 329.

430 ON THE DIFFUSION OF HEAT

cause. This assumption, however, is precluded by the proof,
that heat is not capable of being carried off by the atmosphere,
buf can escape only by radiation, which is dependent on an
elevated temperature. The conclusions seem, therefore, ne-
cessarily to follow, that the original temperature of the earth
must have been at least as low as the lowest natural tempera-
ture, and of course that the mean temperature has been rai-
sed.

While there is this rise, and this equalization of tempera-
ture at the surface, there must be a corresponding rise in the
internal mass. It is obvious that no permanent rise can take
place at the external layer, without a portion of heat being dif-
fused to the internal matter at a lower temperature. It is ob-
vious also, that a portion of the heat received necessarily must
be conveyed to that matter. And as this diffusion is limited
at the centre, the temperature must rise until it become equal
or nearly so through the whole, and as high, or nearly as high,
as that which the solar rays can excite.

Lastly, the rise of temperature must observe certain limits ;
it must continue until that of the surface is such, that as etl
caloric is discharged from it by radiation, as is received by the
solar rays, and it cannot proceed beyond this. The first con-
clusion necessarily follows, when it is proved, that radiation is
the only mode by which caloric can escape from this planet.
The second conclusion is equally evident. -Thus the tenden-
cy is to an equal and uniform temperature. How far this may
be from that which at present exists, it is difficult to deter-
mine. If the increase of heat is accompanied with its more
equal diffusion, so as to establish nearly the same temperature
over the entire surface, it may not proceed much beyond that
which now prevails at the hotter parts of the earth ; for at this,
when extended over the whole, the quantity of caloric radiated

may

cal

AT THE EARTH’S SURFACE. 431

may be equal to that received. And even if it were to rise
higher than this, still, from gradual changes in the laws of or-
ganised matter, or in the species of living beings, not greater
than what seem to have occurred in the past revolutions of the
globe, the existing temperature might be sufficiently compa-
tible with the continuance of animated existence, and with
an order not very different even from that which now pre-.
vails. |
Different views have been presented of the relation of the
temperature of the globe to solar heat. Some have imagined,
that the earth is in a state of progressive refrigeration ; and
while it was believed that the atmosphere could convey heat
onwards without limitation, this conclusion might be drawn.
Others, from considering merely the constant communication
of solar heat, have drawn the opposite conclusion, that its tem-
perature must increase, and this indefinitely. While a more
probable opinion than either, founded on the apparent unifor-
mity of natural operations in those past periods to which any
records reach, is that, the temperature has always been the
same, or nearly the same, as that which now prevails. The |
view which follows from the preceding observations, is differ-
ent from all these, and presents a more perfect arrangement.
The temperature of the globe must, from the mode in which
heat is communicated to it, rise, and at the-same time, as it
advances, must become more equal over the whole surface.
And this rise has its limits ; ; there cannot be either unlimited
increase of heat, or indefinite refrigeration; but the final result
will be a state of permanence and uniformity, the continuance of
which is secured by the very circumstance, that if it is deviated
from, the deviation must check itself.
_ No view has been presented in physical science of equal
grandeur with that established from astronomical observations,
SH? that

432 ON THE DIFFUSION OF HEAT

that amid all the revolutions of the heavenly bodies, an or-
der exists whence the irregularities arising from their mutual
actions do not increase, but are so adjusted, that when they
reach certain limits they recede, and within this state of oscil-
lation the stability of the entire system is for ever secured, It
would gratify the mind, could it be shewn, that a similar sys-
tem exists with regard to the subordinate parts ; or if not, that
a state of permanence in these parts will be ultimately esta-
blished, compatible with the operation of that more general
law under which the order of the universe is maintained. In
the structure of the globe, however, and in the operations to
which it is subject, there are evident causes of disintegration,
which seem incompatible with a state of permanence, and from
which, in the progress of time, those arrangements which con-
stitute it a habitable world must apparently be subverted. For
the Huttonian Theory has been claimed the praise, (with what
justice need not here be inquired), of unfolding a system of
renovation corresponding to this waste. In the opposte Theo-
ry, no similar attempt has been made; its object has been
merely to trace the arrangements which exist in the mineral
kingdom, and from these to infer the order and mode in
which they have been framed; nor have any causes been
pointed out, as, indeed, none seem to follow from the princi-
ples of the theory, by which that disintegration, the occur-
rence of which in past periods is so clearly marked, and the
operation of which, even at present, is to be traced, may be re-
paired. .

If the view, however, which has been given of the relation
of the temperature of the earth to solar heat be just, this defi-
ciency may perhaps be supplied. Inequality of temperature
is the great source of change and of disintegration at the sur-
face ; the expansion and contraction from alternations of heat

and

AT THE EARTH’S SURFACE. 483

and cold, the absorption and expulsion of humidity from the
same causes, the distending force of congelation, and the rapid
precipitation and flow of water, which are the principal, or ra-
ther the sole disintegrating processes of general or uniform
operation, being the results of it. When inequality of tempe-
rature, therefore, shall cease, or be restrained within much nar-
rower limits, an order may be established of less vicissitude,
and less waste, than that which now prevails, and the stability

of which may even remain unimpaired for indefinite time.

weyt sion

This view, if it is not carrying the speculation too far, may
even be extended to all the parts.of our solar system, and the
condition of each planet may be connected in permanence
with that law which appears to regulate the constitution of the
universe. Considering this Earth as passing through a series
of revolutions from its chaotic state to a more permanent and
perfect form, the different planets may be regarded as in a si-
milar progression. Astronomers have often traced the analo-
gy which exists among them, not only in the laws of their mo-
tions, but in the figure of their masses ; they have not failed to
_ remark the flattening at the poles, which can be observed in
some of them, similar to that of our globe, proving a similar
state of fluidity from which this figure has originated; and
they have endeavoured even to draw from the aspect which
they exhibit, indications of the stage of progression in which
they now are *. But they have presented no pleasing prospect
of the final adjustment of this series of revolutions. Regard-
ing the planets as extinct suns, or fragments of suns, or at least
as masses which have been hot and luminous, they have sup-
posed them to be in a state of gradual refrigeration, which will
| terminate

* Histoire de VAstronomie Moderne, tom, ii. p. 726.

434, ON THE DIFFUSION OF HEAT, &c.

terminate in the total cessation of movement and animated
existence. The assumption on which this gloomy hypothesis
is built,—that of the unlimited escape of heat from each plane-
tary mass, is fortunately as false, as the view to which it leads
‘is unworthy of the order and magnificence which the system
of nature displays; and instead of this termination, in what
one of these philosophers emphatically calls the state of Ice
and Death, of silence and repose, we may with more confi-
dence look to the equal diffusion of heat through the mass of.
each planet, as the state of permanence under which it will
exist, and to the equal interchange of heat among all, as the
perfection of the system they form.

XV.

XV. On a New Species of Coloured Fringes, produced by the
Reflewion of Light between Two Plates of parallel
Glass of equal thickness. By Davin Brewster, LL. D.
F.R.S. Evry. & F. A. 8. E.

(Read February 20. 1815.)

URING a series of experiments in which I was lately en-

gaged, for the purpose of determining the law of the
polarisation of light, by successive reflexions from plates of
parallel glass, I observed that all the images of the luminous
body which were formed by more than one reflexion, were
crossed by parallel fringes of coloured light, when the two
plates had a small inclination to each other; and that these
fringes suffered considerable changes, by varying the position
of the plate with regard to the incident ray.

These coloured fringes seemed at first to have the same ori-
gin as those of thick plates, which were discovered by New-
TON, and afterwards examined by the Duke de Cuautnes, Mr
Brovcuam, and Mr Jorpan; and I considered the second
plate of glass as performing the part of the quicksilver in Nzw-
Ton’s glass mirror, or of the metallic speculum in the experi-
ments of the Duke De Cuautnes, and Mr Brovenyam. A
more attentive examination, however, convinced me that this

was

436 ON A NEW SPECIES OF COLOURED FRINGES

was a mistake, and that the coloured fringes constituted a
new class of phenomena, having a different origin from those
of thick plates, though explicable by the beautiful theory of Fits
of easy reflexion and transmission, by which Newton was ena-
bled to explain all the phenomena of the colours of thick and
thin plates.

In order to observe the phenomenon to the greatest advan-
tage, let the light of a circular image. subtending an angle of
1° or 2°, be incident perpendicularly, or nearly so, upon two
plates of parallel glass, placed at the distance of one-tenth of
an inch, and let one of the plates be gently inclined to the
other, till one or more of the reflected images be distinctly se-
parated from the bright image formed by transmitted light,
and received upon the,eye, placed behind the plates. Under
these circumstances, the reflected image will be crossed with
about fifteen or sixteen beautiful parallel fringes; The three
central fringes consist of blackish and whitish stripes, and the
exterior ones of brilliant stripes of red and green light ; and the
central fringes have the same appearance in relation to the
external fringes, as the internal have to the external rings, form-
ed either by thin plates, or by. the action of topaz upon polarised
light. If the two plates of glass are turned round in a plane at
right angles to the incident ray, the reflected images will move
round the bright image, and the parallel fringes will always
preserve a direction at right angles to a line joining the centres
of the bright and reflected 1 images. Hence it follows, that the
direction of the fringes is always parallel to the common section
of the four reflecting surfaces, which exereise an action i: the
incident light.

The position of the plates remaining:as before, let the incli-

nation of the plates, or what is the same thing, the distance of

the

PRODUCED BY TWO PLATES OF GLASS OF EQUAL THICKNESS. 437.

the bright and the reflected image be varied by a gentle mo-
tion of one of the plates, the coloured fringes will be found to
increase in breadth as the inclination of the plates is diminish-
ed, and to diminish as the inclination of the plates is increa-
sed.
In order to determine the law according to which the mag-
nitude of the fringes varies, I employed two plates of paral-
lel glass “3ths of an inch thick, and obtained the following
measures for the fringes which crossed the image that had
suffered two reflexions between the plates. The pencil of
light was incident nearly in a vertical direction upon the
first plate.

Inclination of the Plates. Angular breadth of each Fringe.

1nd’ 26' 50”
2 20 1D i9iB
5 36. . 5 41

Now since 5°86’ : 26’ 50’: : 1° 11’: 5’40*, and since
5 36:13 3 7:2 20:5 27, it follows, that

the breadth of the fringes is inversely as the inclination of the
plates. ;

Owing to the rapid diminution of the fringes, by increasing
the angle formed by the plates, I could not with any degree
of accuracy determine their breadth at greater angles of incli-
nation ; and therefore it still remains to be ascertained whe-
ther it varies with the sine, tangent, or secant of the angles.

If the light of the circular object, instead of falling perpen-
-dicularly upon the plates, is incident at different obliqui-
ties, so that the plane of incidence is at right angles to the com-
mon. section of the plates, no fringes are visible across any of the
images. But if the plane of incidence is parallel to the common
section of the plates, the reflected images increase in brightness
with the obliquity of incidence, and the coloured fringes be-
come more vivid. When the angle of incidence increases
from 0° to 90°, the images that have suffered the greatest num-

Vol. VIL. P. IL. 3K ber

438 ON A NEW SPECIES OF COLOURED FRINGES

ber of reflexions, are crossed by other fringes, inclined to
them at a small angle. At an angle of about 44°, the image
formed by four reflexions, is covered with interfering fringes,
but it is not till the angle of incidence is greater, that this irre-
gularity is distinctly seen on the image formed by two re-
flexions.

Hitherto I had observed no fringes upon the first or bright
image, which is obviously composed of light that has. not suf-
fered reflection from the second plate of glass. By concealing,
however, the bright light of the first image, so as to perceive
the image formed by a second reflection, within the first plate,
and by viewing this image through a small aperture, which I
found of the greatest service in giving distinctness to all the
phenomena, I observed fringes across the first image, far sur-
passing in precision of outline, and in richness of colouring,
every analogous phenomenon which I had seen. When these
fringes were concealed, I also observed other fringes on the
image immediately behind them, and formed by a third re-
flexion, from the interior of the first plate. I now concealed
the second image, upon which the fringes were extremely
bright, and very faint stripes were seen upon the one imme-
diately behind it. |

In examining these phenomena a little more attentively, I
observed thatthe size of the fringes in the first image, varied
with the distance of the eye from the plates, while those on the
second and fourth image diminished with that distance.

The magnitude of this change will be understood from the
following experiments : )

Number of Fringes across the first Image. | Number of Fringes across second image.

Angles of Inci- Bye near. Eye a few inches Eye near. Eye a few inches dis-
dence. distant. tant
0° 6 65
47 4% Sit 5
61 3: 3 4 42
73 Qs Qi 3 3i

When -

PRODUCED BY TWO PLATES OF GLASS OF EQUAL THICKNESS. 439

When the fringes on the second image were inclined to the
right, those on the first image were inclined to the left ; so that
both in point of position and magnitude, the two sets of frin-

_ ges follow a different law.

The preceding measures of the magnitude of the fringes at
different obliquities, were not taken with that accuracy which
is necessary for determining the law of their variation. I have
made numerous experiments for this purpose ; but when the
angle of incidence is considerable, there is always such a de-
gree of distortion in the fringes, and such a perceptible varia-
tion in their magnitude, from the slightest change in the posi-
tion of the eye, that I found it quite impracticable to take mea-
sures in which any confidence could be placed. This difficulty
no doubt arises from the imperfect flatness of the surfaces of
the plates of glass; and I fear that even our best artists .are
not capable of producing better plates than those which I used
in the preceding experiments. The following measures may
be considered as tolerably correct.

The inclination of the plates was not the same as in the pre-
ceding experiments :

Angles of Incidexce. Number of Fringes Number of Fringes
_ across the first Image. across the second Image.
0° 0 we 6
36 56 5 ay
58 48 33 43
62 52 45 3F
71 30 25 2;

If the two parallel plates are placed at any distance whatever,
and the preceding experiments repeated, the fringes will be
found to suffer no change either in their magnitude or direc-
tion,

3K 2 I

440 ON A NEW SPECIES OF COLOURED FRINGES

I now took three plates of parallel glass, that gave the co-
loured fringes when any two of them were put into the proper
position. When the third plate was placed either before the
other two, or between them, or behind them, it did not in the
least degree affect the fringes which they produced. When it
was placed, however, in such a position as to form a new re-
flected image, this image was also crossed by the coloured
fringes.

When the third piece of parallel glass was cemented with
Canada balsam upon the face of the jirst plate, or upon the
back of the second plate, the fringes disappeared. When the
interval between the two plates was filled with water, or with
Canada balsam, the fringes were very faint, though distinctly
perceptible. Hence it follows, that the production of the fringes
depends upon the action of all the four surfaces of the two plates
of parallel glass.

All the preceding experiments were made with plates which
were cut out of the same piece of glass, and had therefore the
same thickness. I now tried plates of different thicknesses,
both when ground parallel, and when cut from common plate
glass; but I could never render the coloured fringes visible,
unless when the glass was parallel, and exactly of the same
thickness in both plates. I also tried plates of topaz, of equal
thicknesses, and plates of sulphate of lime; but though I used
pieces of various thicknesses, I have never bic ice in ma-
king them exhibit the coloured fringes, owing, perhaps, to the
imperfect flatness of their surfaces.

In order to ascertain if the magnitude of the fringes depend-

ed on the thickness of the rns plates, I feito a piece of
parallel crown glass ¢4ssth of an inch thick, and compared the
fringes which it produced, at an inclination of 2° 20’, and
at a vertical incidence, with those produced by another piece
of glass 72th of an inch thick. In the first case, the cir-
cular

PRODUCED BY TWO PLATES OF GLASS OF. EQUAL THICKNESS. 44]

cular image was crossed by five fringes, and in the second
case with seven fringes: But

121 168
re" gas a 5: 7 nearly.
In another experiment, I found, from a mean of five measure-.
ments, that the thickest of these pairs of plates produced frin-
ges each of which had a breadth of 11'10°, when the inclina-
tion of the plates was 1° 58’. Now the other pair of plates
gave fringes 13’ 3” broad, at an inclination of 2° 20”, which:
gives 15’ 29” for their breadth at an angle of 1° 58, and

121 168 Shae Mpa
7000... 1000 se LEO a oO".
Hence the magnitudes of the fringes are inversely as the thick~
nesses of the plates which produce them, at a given inclination ;
and in general the magnitudes of the fringes are in the compound
inverse ratio of the thickness of the plates, and of their angle of
inclination.

Hitherto we have supposed the glass plates to be placed be-
tween the eye and the luminous object, so that only the 2d,
4th, and 6th reflected images were seen. When the eye is
placed between the plates and the luminous object, so as to
perceive the Ist, 3d, and 5th, reflected images, the coloured.
fringes are also seen, having the same characters as those alrea-.
dy noticed.

The phenomena which have been described are equally pro-
duced when the fringes are formed by polarised light, and they
do not suffer the least change when examined by doubly re-
fracting or doubly polarising crystals. :

When the eye is placed at a considerable dis‘ance, either
before or behind the glass plates, all the fringes have a very

distorted.

449 ON A NEW SPECIES OF COLOURED FRINGES

distorted appearance, arising probably from the imperfect. fi-
gure of the reflecting surfaces.

In order to explain the changes which the light undergoes in
its passage through the plates of glass, let AB, CD, Plate XXII.
fig. 1. be a section of two plates at right angles to the common
section of their surfaces, and let RS be a ray of light incident
nearly in a vertical direction. This ray after passing through
the first plate AB, will suffer a small refraction at P and Q,
and emerge in the direction QV parallel to RS. At the point
P, in the second plate CD, the ray TP will be reflected to a,
again reflected to 6, and after suffering a refraction at } and c,
will emerge in the direction cd, forming with RV an angle
equal to twice the inclination of the plates. A portion of the
reflected ray Pa, will enter the first plate at a, and having suf-
fered reflexion and refraction at #, the reflected portion By
will reach the eye at 6 The ray Pabc will likewise suffer a
reflection at ¢ and at e, and will reach the eye at g. In like
manner, a part of the ray PQ will be reflected at Q, and move
in the direction Qrstuv, and another part of it in the direc-
tion swayz, and these rays will suffer several other reflex-
ions ; but the images which they form will be so faint, that
the eye will not be capable of perceiving them. When the
observer, therefore, looks at a luminous body, in the direction
SR, through the glass plates, he will perceive two images, one
of which is a bright image, seen by the transmitted light QV,
and the other is a faint image, seen principally by the reflected
light Pabcd, and composed of several images, formed by the
pencils cd, wv, <4, 2§, and eg. The bright image is not cross-
ed by coloured fringes, but the fringes appear distinctly upon
the other image; and the light by which these fringes are

formed,

PRODUCED BY TWO PLATES OF GLASS OF EQUAL THICKNESS. 443

formed, has suffered two reflexions from the exterior surfaces,
and two refractions at the interior surfaces of the plates.

When the ray RS is incident obliquely, so as to produce
the coloured fringes, the plane of incidence is parallel to the
common section of the plates. In this case, it-is difficult to
represent in a diagram the progress of the rays, as they are re-
flected in a plane at right angles to that in which they are re-
fracted. The changes, however, which the light must under-
go in the production of the fringes, may be understood from
figs. 2, 3, 4, 5,6, '7, and 8, where AB and CD are the two plates.
of glass, inclined at a small angle, and RS a ray of light inci-
dent obliquely, in a plane at right angles to the common sec-
tion of the plate.

In fig. 2. the plates are so arranged, that the incident ray
RS does not pass through the first plate AB. In this case,
the fringes are produced in the same manner as if the ray had.
passed through AB.

In fig. 3. the rays reflected from the plate AD do not pass
through the second plate CD. In this case, the fringes are
produced as formerly.

In fig. 4. the reflection from the external surface mn of the
plate AB, is destroyed by a layer of indurated Canada balsam..
In this case no fringes are produced.

In fig. 5. the refraction and reflection at the interior surface
op of the plate AB, is destroyed by a layer of Canada bal-
sam. In this case no fringes are produced.

In fig. 6. the refraction of the interior surface of the plate
CD is destroyed by a layer of Canada balsam, and in this case
no fringes are produced.

In fig. 7. the reflexion from the external surfaces m n, op,
of the two plates is destroyed, and no fringes are produced.

In

444 ON A NEW SPECIES OF COLOURED FRINGES, &c.

In all these cases, the fringes are obviously produced by a
refraction and a reflexion in each of the two plates, and the in-
‘terfering fringes are produced by the secondary reflexions
‘within the glass plates.

The fringes, however, which appear upon the first or bright
‘images, are produced in a different manner from those formed
by the light that has been reflected from the plate CD; for the
light of which they are composed has suffered two or more re-
flexions within the plate AB, as shewn in fig. 8. and two re-
fractions by the plate CD. These refractions are absolutely ne-
-cessary to the production of the fringes; for they disappear
when the light reaches the eye, without passing through the
second plate. Any variation in the distance of the plates,
when their inclination and thickness remain the same, ought
obviously to produce no change in the appearance of the frin-
ges, as the fits will return in the same manner as before.

In order to compare the preceding phenomena with the
Newtonian Theory of Fits, I propose to resume the investiga-
tion with plates of parallel glass, that differ very considerably
in thickness, and that have their surfaces ground as flat, and
polished as highly as possible; and I have no doubt but that
all the results may be calculated by means of that beautiful
theory.

The fundamental experiment by which I ascertained the
production of coloured fringes by two plates of glass of equal
thickness, has been repeated and verified by my friend M. Bror
of the Institute of France, and was exhibited at a public
meeting of that distinguished body.

XVI.

Fig. 2.

Eng

rured by WEP dears kin?

XVI. An Analysis of the Mineral Waters of Dunblane and
Pitcaithly ; with general Observations on the Analy-
sis of Mineral Waters, and the Composition of Bath
Water and some others. By Jouxn Murray, M. D.
ES. Bor.

(Read November 20. 1814. )

Proprosr to submit to the Society the analysis of a Mineral
Water of the Saline Class, which has lately been discover-

ed in the neighbourhood of Dunblane. The subject may have
rather more interest than usually belongs to researches of this
nature, from the composition of this water being such as pro-
mises to afford a spring of considerable medicinal efficacy, and
from its resemblance to another mineral water, of some ce-
lebrity,—that of Pitcaithly, the analysis of which I have,
from this circumstance, been also led to undertake. The in-
vestigation, too, may afford some illustrations of the different
methods that may be employed in the analysis of waters of
this class, and of the facility and precision which are given to
these researches, by the results that have been established with
regard to the definite proportions in which many bodies com-
bine, and the uniformity of the relations which thus exist be-
tween the compounds they form. And it has led to some
views with regard to the constitution of mineral waters of the
Vor. VU. P. Il. 3.1L saline

446 ANALYSIS OF THE

saline class, which I have applied to the composition of some
of the most celebrated mineral waters. In performing the
principal experiments on the Dunblane water, I had the ad-
vantage of Mr Extis’s co-operation.

J.. ANALysis or THE DunBLaANE Water.

This Water was discovered last summer, and was first taken
notice of, from the circumstance of the frequent resort of flocks
of pigeons to the ground where it breaks out. It appears in
two springs, at the distance of nearly half a mile from each
other, in a field about two miles to the north of Dunblane, the
property of the Earl of Krynour. This district is at no great
distance from the range of the Grampians, to which it as-
cends ; masses of the primitive rocks are spread over the sur-
face, and are found in the beds of the streams ; among which
the conglomerate rock that seems to skirt the Grampians, is
abundant. The prevailing rock of the district itself is the red
sandstone, and it is generally covered by a bed of gravel, in
many places of considerable depth. It is from this sandstone
that the water appears to issue. The spring, however, in both
the places where it breaks out, has been laid open only to the
depth of two or three feet from the surface, and has not been
traced to any extent. Its proper source is therefore unknown,
and it also remains uncertain, how far it may be diluted with
water from the surface, or from other springs. The water from
the lower, or what for distinction may be named the South
Spring, is weaker in taste than the water of the North Spring,
and pone the subsequent experiments, is proved to contain ra-

ther

MINERAL WATERS OF DUNBLANE. 447

ther less foreign matter. The ingredients, however, are the
same, and the difference therefore probably arises from the
water of the lower spring being farther diluted in its course.
This difference led to the analysis of the water of both springs.
It is proper to remark, that both have been submitted to exa-
mination after a season unusually dry.

Analysis of the We ater of the North Spring.

The taste of this water is saline, with some degree of bitter-
ness. . As procured from the principal pool at which it issues,
it is free from smell; procured, however, from some other
pools, at the distance only of a few feet, its smell is slightly
sulphureous, probably owing to impregnation from matter at
or immediately under the soil. Its sensible operation on the
system is that of a diuretic and purgative. The former effect
is usually obtained, when a quantity is taken by an adult,
from an English pint to a quart ; the latter, when more than a
quart is taken. The specific gravity of the water is 1.00475.
It suffers no change in its sensible qualities from exposure
to the air.

The state of the spring is at present such, that any gaseous
impregnation of the water cannot be determined with preci-
sion. Bubbles of air frequently rise from the bottom of the
pool, but this is merely atmospheric air: transmitted through
lime-water, it produced no sensible milkiness; nor does the
water appear to contain any free carbonic acid.

The usual re-agents present with the water the following
appearances *

1. The colours of litmus, violet, and turmeric, are not sen-

sibly affected. ical
° 3 ee 2, Muriate

448 ANALYSIS OF THE

2. Muriate of barytes produces an immediate turbidness,

and rather copious precipitation, which is very slightly,
_ if at all removed. by nitric acid.

3. Nitrate of silver gives a very dense and abundant preci-
pitate.

4. Water of potash produces a turbid appearance, not very:
considerable.

5. Carbonate of potash throws down an abundant precipi-
tate, which disappears with effervescence on adding ni-
tric acid. |

6. Lime water causes no change. )

7. Ammonia does not cause any precipitation, nor does it
even impair the transparency of the water.

8. Oxalate of potash, or of ammonia, occasions a copious
precipitation.

9. Tincture of galls has no immediate sensible effect ; but
after an hour or two a purplish tint is exhibited, which
deepens from exposure to the air, and inclines to olive-
green.

These results establish the following conclusions:: ,

Exper. 1. proves that no free acid or alkaline matter is pre-
sent, nor any alkaline carbonate.

Exper. 2. denotes the presence of sulphuric acid.

Exper. 3. indicates the presence of muriatic acid.

From Exper. 4. and 5. may be inferred: the presence either
of lime, or magnesia, or both.

Exper. 6. and 7. prove that magnesia is not present, nor
argil.

Exper. 8. proves the presence of lime.

Exper. 9. indicates a minute portion of iron.

‘ The.

MINERAL WATERS OF DUNBLANE. 449,

The saline taste of the water, and the precipitation so abun-
dant by nitrate of silver, render probable the presence of mu-
riate of soda, and it is accordingly obtained, when the water
is evaporated nearly to dryness, cubical crystals of it forming,
in the saline liquid.

From the whole, therefore, the principal ingredients of this.
water may be inferred to be muriates of soda and lime, with a.
smaller portion of a sulphate, and a minute quantity of iron..
These conclusions suggested the following method of ana-.
lysis. ‘

An English pint of the water was evaporated to dryness ;
and the solid residuum was exposed to a heat approaching to
redness, until it became perfectly dry. It weighed while warm.
47 grains. It quickly attracted moisture from the air, so that
its surface'soon became humid, and on leaving it exposed for
twenty-four hours, a considerable portion: was dissolved, form-
ing a dense liquor, while a portion remained undissolved.

The whole solid matter being rendered dry, was submit-
ted to the action of alkohol, with the view of separating by so-
lution the muriates of soda and lime, of which it was supposed
to be principally composed... It,is well known, that this me-
thod is liable, in some degree, to two sources of error ; the one,
that a little muriate of soda is dissolved by the alkohol with the
muriate of lime ; the other, that even when a large quantity. of
alkohol is employed, the undissolved muriate of soda retains a
small portion of muriate of lime. In estimating the quanti-
ties from the results, these errors, indeed, in some measure,
counterbalance each other ; but still they may exist in different
degrees, according to the quantity and strength of the alkohol,
and it is necessary therefore to obtain per fect pr ecision, to ob-
viate them as far as possible.
With

450 ANALYSIS OF THE

With this view, the entire matter was digested with repeat-
ed portions of alkohol, of the specific gravity of $36, until
about six times its weight had been employed ; the’solvent ac-
tion being aided by frequent agitation, and an occasional heat
of about 100°. It was then lixiviated with a small portion of
‘distilled water, to remove more effectually from the muriate of
soda any adhering muriate of lime. ‘The different liquors be-
ing mixed, were evaporated to dryness ; and this dry mass was
again submitted to the action of aTROROT: more highly rectified,
(a of the specific gravity of 825), and in smaller quantity,
so as to dissolve only that part of it which was muriate of lime.
A small portion of muriate of soda, which had been dissolved
in the first digestion, was thus obtained, and was added to the
residue of that operation. The whole undissolved matter be-
ing dried at a low red heat, weighed while warm 28.5 grains :
it was in small grains, having a taste purely saline. ‘The alko-
holic solution afforded, by evaporation, a matter which enter-
ed into fusion, and which, after being dried at a heat approach-
ing to redness, weighed while warm 18.2 grains. It was high-
ly deliquescent, so as to increase quickly in weight, and in a
short time became humid on the surface.

These two products were evidently principally muriate of
soda, and muriate of lime. But it was necessary to ascertain
if they were entirely so, as both of them might contain small
portions of other ingredients.

The matter anole ed by the alkohol, supposing it to “ye mu-
riate of lime, would require for its conversion into sulphate of
lime about sixteen grains of sulphuric acid, of the usual
strength. Kighteen grains were added with a small portion of
distilled water, and heat was applied ; vapours of muriatic acid

were discharged: To render the mutual action more com- ..

plete, small portions of water were successively added, the soft
mass

— a

MINERAL WATERS OF DUNBLANE. 451

mass being frequently stirred, and when the vapours had cea-
sed to exhale, the heat was raised to redness, to expel any ex-
cess of acid. The dry matter weighed 22 grains, precisely the
quantity that ought to be’ phiaied from 18 grains of muriate:
of lime.

It was diffused in a ere of water, which it at first ab-.
sorbed with a hissing noise. The- water, after having been
added in successive quantities, with. frequent agitation, being
poured off, the undissolved matter was dried at a low red
heat : it weighed 18.5 grains, and formed.a soft white powder,
free from taste. The water poured off was very slightly acidu-
lous. This was neutralised by ammonia; it was then evapo-
rated to dryness, and the solid matter was heated to redness.
On again submitting it to the action of a small quantity of wa-
ter, a portion remained undissolved, which weighed when dri-
ed 2 grains. 7

There were thus obtained 20.5 grains of sulphate of lime, a
quantity equivalent to 16.7 of dry muriate of lime. The small
portion of liquor which remained in the last operation, had 2
bitterish taste: by spontaneous evaporation, it formed acicular
crystals ; diluted with distilled water, it became slightly turbid
on adding oxalate of ammonia, and more so on the addition of
alkohol ; abn in the latter case, the transparency was restored.
on adding water. With a minute portion, therefore, of sul-
_ phate of lime, it appeared to be principally sulphate of soda,
derived from a little muriate of soda, which, notwithstanding
the precautions that were employed, had adhered to the muri-
ate oflime.

The matter which remained undissolved by the alkohol,
weighed, it has been stated 28.5 grains. It remained to as-
certain if it-were entirely muriate of soda.

Being

452 ANALYSIS OF THE

Being agitated with about half an ounce of distilled water,
the greater part was dissolved. The portion which remained
undissolved, after being washed with small quantities of distil-
led water, and. dried, weighed 2.4 grains. To this mattera
little diluted nitric acid being added, a slight effervescence was
excited: a thin crust, too, adhered to the sides of the small
glass globe in which the last stage of the evaporation had
-been performed, which was dissolved with effervescence by a
weak acid. The quantity of carbonate of lime thus indicated,
may be estimated at 0.5 grain. The remainder of the undis-
solved residue being washed and dried, was heated with two
or three drops of sulphuric.acid; and was thus rendered soluble
in water. When neutralized by ammonia, the solution became
milky ; but its transparency was restored by adding more wa-
ter.; it became quite turbid on adding oxalate of potash, and a
precipitate was thrown down by alkohol. It was therefore
sulphate of lime. Its quantity may be stated at 2 grains.

The solution had a taste purely saline. The test of. oxalate
of ammonia, however, shewed the presence in it of a small
quantity of lime; the addition of the oxalate was therefore
continued as long as any precipitation took place, and the pre-
cipitate was collected and dried. It weighed 1.3 grains. This
production of oxalate of lime evidently arose from the pre-
sence of a small portion of muriate of lime, which, notwith-
standing the precautions that had been employed, had adhe-
red to the muriate of soda. Supposing that this had not esca-
ped the action of the alkohol, but had been dissolved by it,
and in the subsequent stage of the experiment, been convert-
ed into sulphate of lime, it would have increased the quantity
of this sulphate about 1.2 grains, making it therefore 21.7,
equivalent to 17.6 grains of dry muriate of lime which the pint
of water contains.

The

\ MINERAL WATERS OF DUNBLANE. 453

The solution contained also a minute quantity of sulphurie
acid; for after removing any slight excess of oxalic acid that
might have been present, it still gave a precipitate on the ad-
dition of muriate of barytes. Supposing this, as well as the
rest of the sulphuric acid, to have existed..in the water in the
state of sulphate of lime, it will increase the quantity,of that
ingredient, (calculating from the weight of the precipitate of
sulphate of barytes obtained), from the 2 grains formerly noti- -
ced to 2.9.

There appeared now to remain nothing but pure muriate of
soda. ‘The solution by slow evaporation afforded that salt in
cubical crystals, which, dried at a low red heat, weighed 24.5
grains. Allowing 0.8 ofthis as the portion of product formed
by the action of the muriate of barytes, it leaves 23.7 grains.
And if to this be added one grain, as the equivalent of the
small portion of sulphate of soda, already noticed as formed by
the action of the sulphuric acid on the muriate of soda adhe-
ring to the muriate of lime after the operation of the alkohol, |
it gives the quantity of muriate of soda at 24.7 grains.

From these results, the solid ingredients in a pint of this wa- -
ter appear to be

Muriate of soda - 24.7 grains...
Muriate of lime, - 17.6
Sulphate of lime, - 2.9
Carbonate of lime, —_ - 0.5

45.7.

With a trace of iron..

Having completed the analysis in this manner, I wished to
confirm it by a different method. A very simple one present-

ots VILE LT 3M ed

454 ANALYSIS OF THE

ed itself,—to reduce by evaporation to dryness,—obtain the
sulphate of lime as before,—then, dissolving the mixed mass of

muriate of lime, and muriate of soda in water, decompose the _

muriate of lime by oxalate of ammonia, so as to find the quan-
tity of it present, and after evaporation to volatilize the muri-
-ate of ammonia by heat, and thus obtain the muriate of soda.
The results in this mode ought to correspond with those
in the former; and the one, therefore, afford a confirma-
tion of the other, or lead to the discovery of any fallacy if it
exist.

A pint of the water was evaporated to dryness, and afford-
-ed, as before, 47 grains of solid matter. This being submitted
to the action of a small quantity of distilled water, was dissol-
ved, with the exception of a residue of sulphate of lime, which
weighed 2.6 grains, and a little carbonate of lime, which may
-be estimated, as before, at 0.5 grain.

To the clear solution, a solution of oxalate of ammonia was
added as long as any turbid appearance was produced ; and af-
ter the precipitate had subsided, the liquor was heated nearly
to boiling, to render the mutual action and the precipitation
more perfect. The precipitate being repeatedly washed with
distilled water, was dried by the heat of a sand bath raised
gradually, and kept lower than a red heat. It weighed 21
grains. The quantity of muriate of lime which would be equi-
valent to this, cannot be inferred with certainty, from any pre-
vious analysis of oxalate of lime; for as the oxalate cannot be
exposed to a red heat without decomposition, it cannot easily be
subjected to a precise degree of heat, by which we can be cer-
tain of obtaining it in a uniform state of dryness*. It is ne-

cessary,

* Referring to those analyses which may be supposed to be most accurate, 21
grains of oxalate of lime will be found equivalent to various proportions, from
17.5 fo 19.9 of muriate of lime.

7

MINERAL WATERS OF DUNBLANE, 455

eessary, therefore, that in every case, the quantity of lime
should be found in the oxalate that is operated on. The above
quantity of 21 grains was converted by calcination into carbo-
nate of lime, and this being decomposed by muriatic acid, the
quantity of muriate of lime obtained, dried at a low red heat,
and weighed while warm, amounted to 18.3 grains.

The liquor poured off from the precipitate, was evaporated
to dryness ; and to expel the muriate of ammonia formed by
the action of the oxalate of ammonia on the muriate of lime,
the heat was continued while any vapours were disengaged,
and at the end was raised nearly to redness. The dry mass
weighed, while warm, 25 grains. Being dissolved in water, its
solution was rendered very slightly turbid by the addition of
muriate of barytes, shewing the presence of a minute portion of
sulphuric acid. A quantity of precipitate was collected, which,
when dried, weighed 0.8:grain. Supposing the sulphuric acid
of this to have originally existed in the water, along with the
other portion of this acid, in the state of sulphate of lime, it
gives a proportion of that sulphate of 0.5 grain, and of course
increases the quantity of it from the 2.6 grains obtained by
evaporation to 3.1 grains. An equivalent quantity must at the
same time be subtracted from the proportion of muriate of |
lime, which may therefore be reduced to 18 grains.. By eva-
poration of the liquor, muriate of soda was obtained, weighing,
when it had been dried at a low red heat 24.3 grains. Of this
a small portion (0.4) would be formed by the muriate of ba-
rytes, which requires to be deducted; but then the sulphuric
acid which existed in the mass, could, after the action of the
oxalate of ammonia, and the exposure to a red heat, exist in it
only in the state of sulphate of soda, in the production of which
an equivalent portion of muriate of soda would be decompo-
sed. The quantity of muriate of soda obtained, therefore, by

3 M.2 the

456 ANALYSIS*OF THE

the evaporation, may be regarded as the just proportion indi-
cated by the analysis.

The results, then, by this method, agree very nearly with
those by the other ; being of solid ingredients in a pint of the
-water,

Muriate of soda, - 24.3 grains.
Muriate of lime, ™ 18
Sulphate of lime, - 3.4
Carbonate of lime, - 0.5

45.9

With a trace of iron.

_ With regard to both analyses, a small correction is to be
made in the proportion of sulphate of lime. The mode of as-
certaining it, by evaporation, being rather imperfect, I after-
wards determined it by the more accurate method of precipita-
tion by muriate of barytes ; applying this re-agent with a slight
excess of acid, so as to prevent any precipitation of carbonate.
The quantity of precipitate thrown down from a pint of the
water, amounted, after drying at a low red heat, to 6.1 grains,
equivalent to 3.5 grains of sulphate of lime. As the portion
of sulphate of lime thus obtained, above that obtained by the
evaporation, would remain principally mixed with the muriate
of soda, the quantity of that ingredient falls to be reduced a
little, and may therefore be stated at 24 grains.

It remained to ascertain the proportion of iron. “The quan-
tity, however, was evidently so small as to present a difficulty.
Succinate of ammonia, and benzoate of soda, produced little
or no effect on the water in its natural state. Infusion of galls
produced, after some hours, a dark colour, and a precipitate
very slowly subsided. This method has been employed to as-

certain

MINERAL WATERS OF DUNBLANE. 457

certain minute quantities of iron, and I endeavoured to avail
myself of it,—adding to the water infusion of galls, in small
successive portions, at the interval of a day or two, as long as
the.colour appeared to be rendered deeper ; leaving it exposed
to the air for a longer time, that the whole matter rendered in-
soluble might subside; and, lastly, washing the precipitate,
drying and calcining it, to consume the vegetable matter, and
obtain the oxide of iron. The difficulty, however, attending
this method, is that of precipitating entirely the iron, the li-
quor never becoming colourless. In one experiment, conduct-
ed with much care, the quantity of the calcined product from
two pints amounted to 0.4 grain ; but it consisted partly of
carbonate of lime. ‘To remove this, pure muriatic acid diluted
was added in excess, and a moderate heat was applied; the
precipitate was entirely dissolved, and the liquor acquired a
deep yellow colour. Being farther diluted, a little pure am-
monia was added to it, in a close phial, to precipitate the oxide
of iron, while the lime should remain dissolved. The quanti-
ty thus obtained, when dried, amounted to 0.27 grain.

This method being liable to the above objection, I employ-
ed another: Two pints of the water were evaporated: when
reduced to about two ounces, a brownish coloured sediment
was deposited, which was removed; the evaporation was car-
ried to dryness, and the dry mass was re-dissolved in distilled
water. The insoluble residue was of a greyish colour, and to
this, the deposite formed during the evaporation was added.
It was known by previous experiments, that the greater part
of the iron was separated in this way; the insoluble matter,
when digested with muriatic acid, affording a liquor, when di-
luted with water, which gave, after neutralisation with ammo-
nia, a deep colour with tincture of galls. To ensure, however,
the more perfect separation of the iron, ammonia was added to

the

458 ANALYSIS OF THE

the solution of the solid matter which had been procured by
evaporation, and care being taken that the ammonia was free
from carbonic acid, little or no precipitation could take place
but of oxide of iron. A yellowish flocculent precipitate sub-
sided slowly, which, after being washed, was added to the inso-
luble residue.

The insoluble matter thus collected consisted, as the prece-
ding steps of the analysis establish, chiefly of sulphate, with a
smaller portion of carbonate of lime, with which was mixed the
oxide of iron. A drop or two of sulphuric acid was added, to
convert the carbonate into sulphate of lime; and heat was ap-
plied to expel any excess of acid. A little pure muriatic acid
was then added to dissolve the oxide of iron, and to form with
more certainty the red muriate, soluble in alkohol, a drop of
nitric acid was added along with it. On applying heat, with
the addition of a little water, to. favour the action, a yellow co-
lour was acquired. When the excess of acid was nearly dissipa-
ted, the mass was repeatedly lixiviated with alkohol, in which
sulphate of lime being insoluble, the muriate of iron only
would be dissolved.. ‘The alkohol acquired accordingly a yel-
low colour. Being evaporated by a gentle heat, it gave a resi-
duum, which, on a drop of nitrous acid being added, became
of a deep reddish-brown colour, and after being heated strong-
ly, weighed 0.34 grain. Re-dissolved in muriatic acid, it form-
ed a rich yellow coloured solution, and gave a deep colour with
tincture of galls.

Even in this way, the whole iron is not obtained ; for the so-
lution of the saline matter, though ammonia had been added
to it, to precipitate the iron, still gave a weak colour with galls.
The quantity therefore is rather under-rated. Taking the
above, however, as the proportion, the whole composition will
be in a pint of the water of the North Spring,

Muriate

MINERAL WATERS OF DUNBLANE, 459

Muriate of soda, » 24 grains.
Muriate of lime, - 18
Sulphate of lime, - 3.5
Carbonate of lime, - 0.5
Oxide of iron, - 0.17
46.17

Analysis of the Water of the South Spring.

The water of this spring has a taste similar to that of the
other, but rather weaker: it produces similar medicinal effects.
In the present state of the spring, its strength is more vari-
able, according to the state of the weather. From this circum-
stance, and from its being rather weaker, it has probably a
greater intermixture of surface-water, or of the water of other
springs. When taken up after continued dry weather, it af-
forded, by evaporation, 42 grains of solid matter from a pint ;
the other affording, at the same time, 47 grains. Its specific
gravity was found to be 1.00419. It was in this state, the
strongest in which it was found, that it was submitted to the
following examination.

The application of re-agents produced the same appearances
as with the water of the North Spring, indicating, therefore,
the presence of the same ingredients. To determine this
with more precision, and to ascertain the proportions, the same
‘methods of analysis were employed which had been used with
regard to the other. It will be sufficient to state the results by
one method,—the second of those before described.

A pint of the water was submitted to evaporation, and af-
forded of dry matter, weighed while warm, 42 grains. This

was

460 ANALYSIS OF THE

was re-dissolved in distilled water. There remained undissol-
ved a portion, which, when thoroughly dried, weighed 2.5
grains. This suffered a very slight effervescence with muria-
tic acid, similar to that excited in the insoluble matter of the-
water of the North Spring ; a similar thin crust, too, had form-
ed on the sides of the glass capsule, which was removed with.
effervescence by a drop of muriatic acid. The relative propor-
tions, therefore, of sulphate and carbonate of lime may be re-
garded as the same: and the insoluble residue will thus consist
of 0.3 of carbonate, and 2.3 of sulphate of lime. By precipi-
tation by muriate of barytes from another pint of the water, si-
milar results were obtained. hae,

To the clear liquor, oxalate of ammonia was added’ as long

as it produced any turbid appearance. The precipitate collected
and dried; being converted by calcination into carbonate of
lime, afforded, when acted on by muriatic acid, 16 grains of dry
muriate of lime. :

The solution poured off from the- precipitate, was evapo-
rated to dryness, and the dry mass was exposed to a heat gra-
dually raised to redness, until it ceased to exhale any vapour.
The muriate- of ammonia formed by the action of the oxa-
late of ammonia on the muriate of lime, was thus expelled,
and the muriate of soda of the water remained. ~ It weighed
22.5 grains.

The results, then, by this sLeedlods are from a pint of the
water,

Muriate of soda, - 22.5 grains.
Muriate of lime, - 16
Sulphate of lime, = - 2.3;
Carbonate of lime, - 0.3
Oxide of iron, - 0.15

41.25

The

MINERAL WATERS OF DUNBLANE. 461

The proportion of iron | have stated as similar to that of the
North: Spring, from the colour produced by the tincture of
galls being nearly the same.

From the almost perfect similarity in the composition of
the two waters, with regard to the proportions of their ingre-
dients, there is every reason to conclude, that they are from
the same spring ; the weaker being either mixed with surface
water at the pool, or being diluted in its course.

The determination of the composition of this water, suggests
the question, whether this is such as to account for the medi-
cinal effects it produces. It acts, as has been stated, as a diu-
retic, and in a larger dose, as a cathartic. This water, and the
mineral water of Pitcaithly, present, in some respects, a pecu-
liarity. The greater number of saline waters which have a
purgative quality, contain magnesian salts, to which, as they
are known to act as cathartics, the effect is obviously to be as-
cribed. Of the ingredients of the Dunblane and Pitcaithly
Springs, muriate of lime is scarcely known to have any purga-
tive power in its pure form, and if muriate of soda possess it,
it is only in an inconsiderable degree. Still, there can be no
doubt, that it is to this impregnation that their operation is
owing, and they afford a proof, therefore, of what is indeed
sufficiently established, that the powers of mineral waters are
often much greater than could be expected from the nature
and quantity of their ingredients, and that the action of saline
substances is increased, and considerably modified, when they
are in a state of great dilution.

Independent of its purgative operation, and its adaptation to
the treatment of diseases in which this is advantageous, its
composition may probably render it a remedy of efficacy in
some constitutional affections, particularly in scrofula. Mu-

riate of lime has attained some celebrity in the treatment of
Vox. VII. P. IL 3N this

462 ANALYSIS OF THE

this disease ; it is a substance of considerable activity in its ef-
fects on the living system ; and it will probably operate with
more effect, and more advantage, in the state of dilution in
which it is presented in a mineral spring, than when given in
a more concentrated form. The muriate af soda may coincide
with it in efficacy, and will be of advantage from its grateful taste,
and its stimulant action on the stomach. And the chalybeate
impregnation will communicate some degree of tonic power.
When employed in such cases, it probably ought to be given
in smaller doses, than when the advantage to be derived from
it depends on its purgative operation; and it may even prove
more advantageous, if given in a state of greater dilution. I
shall in the sequel have to state a view of its composition,
which connects it with some mineral springs of great celebrity,
and particularly with the Bath waters.

Dunblane, as a watering-place, would be possessed of consi-
derable advantages. Situated between the range of the Ochil
Hills and the Grampians, it is well sheltered, and hence enjoys
a mild atmosphere; and the soil, from being a bed of gravel
for a number of miles around, is extremely dry,—an advantage
inestimable in a moist climate.

SEER Ener: n> ~.-0-s seein

IJ. Awatysis oF PrrcarrHty Water.

The water of Pitcaithly may be regarded as the principal mi-
neral water of the saline class in this country. Dr Donatp
Monro shewed, that, along with a little mild‘ calcareous earth,
it contained muriate of soda, with a deliquescent salt, which
he inferred to be chiefly “ a calcareous marine,” that is, muri-
ate of lime*. An analysis of it was published a number of

; years

* Philosophical Transactions, vol. Ixii.

MINERAL WATERS OF DUNBLANE. 463°

years ago, executed by Messrs Sropparr and Mrrcuerz of
Perth. ‘There are different springs, the waters of which they
found to be somewhat different in strength. The nature of
the impregnation is in all of them, however, the same.—Select-
ing the strongest it contains, according to their analysis, the
following ingredients in an English pint : .

Atmospheric air, == 0.5 cubic inch.
Carbonic acid gas, - 1
Muriate of soda, - 12.5 grains.
sa lime! ci » gag
Sulphate of lime, “ 0.7
Carbonate of lime, - 0.6 *

The composition of this water, according to this analysis, is
very similar to that of the Dunblane water. No account is gi-
ven, however, so far as I have been able to discover, of the
manner in which it had been executed, and it is therefore un-
certain to what state of dryness the ingredients had been
brought to which their proportions are referred. Hence no
comparative estimate can be made of it with any other mine-
ral water; and this led me to undertake its analysis, in the
same manner as that of the Dunblane water.

Pitcaithly is situated in the valley of Strathern, and though
at rather a greater distance from the front range of the Gram-
pians than Dunblane, it is not improbable that the spring may
have a similar origin with the Dunblane one, and may rise
from the red sandstone which appears to form the first rock

3N 2 on

% Statistical Account of Scotland, vol, viii.

464 ANALYSIS OF THE

on descending from the —— apete and to extend over alt
this district.

The taste of this wits is saline, and ‘Sipe: bites Com-
paring it with the Dunblane water, both being tasted at the
same time, the taste of the Dunblane water is stronger, and in
particular more saline than that of the other. The medicinal
operation of the Pitcaithly water, in the sensible effects it sis
duces, is diuretic and purgative. .

The gaseous impregnation of the water could be examined
properly only at the spring, which I had not the opportunity
of doing. But having procured a quantity of the water, I sub-
mitted it to the same examination as in the preceding analy-
sis, to ascertain its solid contents. The usual re-agents produ-
ced the following appearances : |

1. The colours of litmus, violet, and turmeric, were scarcely
affected. If there were any change, it was that of the.
litmus becoming more blue, and that of the violet-.
green; but this was so slight as to be rather doubt-
ful. The turmeric underwent no change. —_

2. Muriate of barytes produced a turbid appearance and
precipitation ; but this was much less considerable
than in the Dunblane water. The TanADERCY was

- not restored by nitric acid.

3. Nitrate of silver BESHES a very dense and. copious Boe

cipitate. ‘i best

4, Water of potash gave. a milkiness : “not, oS BEL ty
able. tae Pee a

5. Carbonate of notaels threw. Soa a - copious Bee oa
which disappeared with effervescence on adding nitric
acid. | | |

: 6. Lime

4

MINERAL WATERS OF DUNBLANE: 465.

6. Lime water had no sensible effect.
7. Ammonia, when perfectly free else carbonic acid, caused
no turbid appearance.
8. Oxalate of ammonia produced an abundant ihc ee
tion.
9. Tincture of galls, added in a very minute quantity, did

pine not immediately produce any effect, but after a few:

hours, a dark colour appeared, which gradually deep-
ened, a to an olive-green..

With all these tests, the generat results are the same as those’
from the operation of the same tests on the Dunblane water.
In experiment 7th, the ammonia, if not perfectly free from
carbonic acid, produced a slight turbid appearance, and even
when in its purest state, a very slight opalescent hue was per-
haps apparent ; but this obviously depended on. the presence
of a little carbonic acid; for when a drop or two of nitric acid
was previously added, and the water heated, no such appear-
ance was produced; or, if boiled strongly, without any addi-
tion of acid, on restoring the original quantity of liquid, by

adding distilled water, the transparency was not in the slight-
est degree altered on adding pure ammonia. The slight pre-

cipitate, too, which did occur in any case, was dissolved by the:
most minute quantity of muriatic acid with effervescence ; and
this solution became turbid on adding oxalate of ammonia,
proving the precipitate to have been carbonate of lime.

The same general conclusions, then, with regard to the na-
ture of the ingredients, are to be drawn from the preceding
results as from the application of the same tests to the Dun-.
blane water. They suggest of course a similar mode of ana-
lysis. I preferred the second of the methods above described,,
as being the most simple, and easy of execution.

| An

466 j ANALYSIS OF THE

An English pint of the water was submitted to evaporation.
Before the matter became dry, numerous cubical crystals were
formed, indicating the presence of muriate of soda; when dry,
the solid matter entered readily into fusion with effervescence,
denoting the predominance of muriate of lime. The dry mat-
ter was highly deliquescent. After exposure to a heat inferior
rather to redness, it weighed while warm 35 grains.

This dry matter was re-dissolved in about ten times its
weight of distilled water. A small portion remained undissol-
ved, which, being washed and dried, weighed 1.2 grain. A
little diluted muriatic acid dropt upon this, excited slight ef-
fervescence ; but the greater part remained undissolved, and
weighed, after washing and exsiccation, 0.9 grain. It was sul-
phate of lime. A very thin crust adhered to the sides of the
glass globe in which the last stage of the evaporation had been
performed. This was dissolved with effervescence by diluted
muriatic acid, and the solution became quite turbid on adding
oxalate of ammonia. The quantity of carbonate of lime thus
indicated, adding the portion abstracted, as above, from the
sulphate, cannot be estimated at more than 0.5 grain. These
results were confirmed by precipitation from another portion
of the water by muriate of barytes, the proportions indicated
being nearly the same.

The liquor poured off from the insoluble residue, being di-
luted with distilled water, oxalate of ammonia was added to
it, as long as any turbid appearance was produced ; and after
the subsidence of the precipitate, the liquor was boiled a little,
to render the decomposition and precipitation complete. The
clear liquor was then evaporated to dryness, and the dry mass
was exposed to heat, to volatilize the muriate of ammonia, the
product of the action of the oxalate of ammonia on the muri-
ate of lime; the heat being continued as long as any vapours

exhaled,

MINERAL WATERS OF DUNBLANE. 467

exhaled, and at the end being raised to redness. The muriate
of soda thus obtained, weighed 13.4 grains. By solution and
crystallisation it was obtained in cubes.

The precipitate of oxalate of lime having been thoroughly
washed, was exposed in a sand bath to a heat short of redness,
until it had ceased to exhale any vapours, and appeared per-
fectly dry ; it weighed 23.8 grains. The portion of muriate of
lime equivalent to any quantity of oxalate of lime, cannot, as
has been already remarked, be exactly assigned, from the diffi-
culty of bringing the oxalate to one uniform state of dryness,
But, according to the most accurate analyses, 23.8 grains of dry
oxalate are equivalent to 20 grains of dry muriate. To avoid
any error, however, the oxalate was converted into carbonate
of lime by calcination ; and this, decomposed by muriatic acid,
afforded 19.5 grains of dry muriate of lime.

The proportions, then, of the saline ingredients in an Eng-
lish pint of the Pitcaithly water, are according to this ana-
lysis,

Muriate of soda,

13.4 grains.

' Muriate oflime, — - 19.5
Sulphate —-—-—___ - 0.9
Carbonate - 0.5

34.3

To which are to be added of aérial ingredients,

Atmospheric air, = - 0.5 cubic inch.
Carbonic acid gas, - 1 cubic inch.

It also gives slight indications of the presence of iron; but
as far as can be judged from the shade of colour produced by
tincture of galls, the quantity is much smaller than in the Dun-

blane

468 ANALYSIS OF THE

blane water. It does not admit, therefore, of being determi-
ned with much accuracy by actual experiment.

After I had completed the preceding analysis, a view occur-
red to me with regard to the composition of these waters, dif-
ferent from that which has been stated above; and which, if
just, may lead to conclusions of some interest with regard to
the constitution of mineral waters of the saline class. This I
have lastly to illustrate.

IIT. OsservaTIONS ON THE COMPOSITION OF SALINE MINERAL
WATERS.

It is a question not unequivocally determined, and perhaps
not capable of being determined, in what state the saline in-
gredients of a mineral water exist,—whether the acids and ba-
ses are in those binary combinations which constitute the dif-
ferent neutral salts, or whether they exist in simultaneous
combination, the whole acids being neutralised by the whole
bases. If the former, which is the more common, and per-
haps the more probable opinion, be adopted, it is at least cer-
tain, that the state of combination may be modified by the
analytic operations, and that the binary combinations obtained
by these, may not be precisely those which existed in the wa-
ter. In the case of the Dunblane water, for example, the in-
gredients obtained are muriate of soda, muriate of lime, and
sulphate of lime. Now it is possible that the sulphate of lime

may

MINERAL WATERS OF DUNBLANE. 469

may be a product of the operation, not an original ingredient.
The sulphuric acid may exist rather in the state of sulphate of
soda, and when, in the progress of the evaporation, the liquor
becomes concentrated, this salt may act on a portion of the
muriate of lime, and by mutual decomposition, form cor-
responding portions of muriate of soda, and sulphate of
lime. any 4 |
A question of this kind is not merely one of speculation, but
the solution of it may sometimes throw light on the proper-
ties of mineral waters, particularly on their powers of affecting
the living system: The present affords.a very good example
of this. Sulphate of lime is a substance apparently inert. If
it exist, therefore, as such in the water, it can contribute no-
thing to its efficacy. But in the other state of combination
which is supposed, both the quantity of the muriate of lime,
the more active ingredient, will be greater, and the presence of
sulphate of soda will in part account for the purgative opera-
tion which the water exerts. |
There is no very direct, and perhaps no decisive experiment
by which this question may be determined ; for any method
which would cause the separation of either substance as a bina-
-ry compound, may also be conceived to operate by causing its
formation. Thus, though sulphate of lime is obtained by eva-
poration, this is no proof of its prior existence, since the con-
centration of the solution might equally cause its formation,
by favouring the action of the sulphate of soda, if it exist, on
the muriate of lime. Its separation by a precipitant, by alko-
hol for example, even if it were obtained, is liable to the same
ambiguity ; a certain degree of concentration of the watery. so-
lution would be necessary for the effect, and the farther ope-
ration of the alkohol might be precisely on the same principle,

—diminishing the solvent power of the water, and thus aiding
Vou. VII. P. I. 80 the

470 ANALYSIS OF THE

the force of cohesion, in determining the combination of the
ingredients which form the least situble compound. If a dif-
ferent mode of analysis were had recourse to, if the whole lime,
for example, were precipitated by any re-agent, there would
still remain the uncertainty with what it had been combined,
whether entirely with muriatic, or partly with sulphuric acid ;
and there is no mode of determining this, by obtaining the
other product of the action of the re-agent, which would not
be liable to equal ambiguity ; or, if the sulphuric acid were ab-
stracted by a re-agent, there would equally be the uncer-
tainty, whether it had been previously combined with soda or
lime.

If sulphate of lime did not separate when the water was re-
duced by evaporation so far, that, from the known solubility
of the sulphate, the precipitation of it ought to take place to a
certain extent, it might be concluded that it did not exist.
Yet even this conclusion, were the fact found to be so, (which
it is on making the experiment), is invalidated by the result,
sufficiently established, that salts, by their mutual action, of-
ten increase the solubility of each other, and the sulphate
of lime might, from this cause, be retained dissolved, in a
smaller quantity than it would require by itself for its solu-
tion.

One kind of proof may be given, that of shewing, that a
much larger quantity of sulphate of soda, than what analysis
indicates in this water, may exist in it, without any precipita-
tion of sulphate of lime. I added to different portions of the
water (four ounces each) 5, 10,15, 20, and 30 grains of sul-
phate of soda. In none of the experiments was there any im-
mediate effect, and even after twenty-four hours, there was no
turbid appearance, or apparent change. In the greater num-
ber of these proportions, the quantity of sulphate of soda was

| more

MINERAL WATERS OF DUNBLANE. 471

more than sufficient to convert the whole muriate of lime in
the water into sulphate ; and, according to the known solubili-
ty of this sulphate, the quantity of water was not sufficient to
retain it all dissolved. ‘This quantity was even reduced to a
certain extent by evaporation, without any precipitation. The
result seems therefore to prove, that sulphate of lime had not
been formed, and that sulphate of soda may exist with muriate
of lime in solution without decomposition, in the state of dilu-
tion which this mineral water affords.

Another result which I obtained, and which so far favours
the opinion that the sulphate of lime is formed in the pro-
gress of the evaporation by the reciprocal action of sulphate
of soda and muriate of lime, is, that when a small portion of
sulphate of soda has been added, the quantity of sulphate of
lime obtained is increased: when 10 grains, for example, of
crystallised sulphate of soda were added to a pint of the water,
after evaporation to dryness, 4 grains of sulphate of lime,
which is double the proportion that the water would otherwise
have yielded, were obtained,—affording a proof that when sul-
phate of soda is dissolved in the water, it produces, in the pro-
gress of the evaporation, a corresponding portion of sulphate
of lime, and of course also of muriate of soda.

These results do not absolutely establish the conclusion, that
the sulphuric acid exists in this water in the state of sulphate
of soda ; yet, on the whole, this is the more probable opinion.
If it be admitted, the preceding statement of the ingredients,
and their proportions, must be altered. The sulphate of lime
is of course to be omitted. The sulphate of soda, which is to
be substituted for it, cannot be obtained by any method ; but
the quantity of it may be inferred, from the quantity of sul-
phate of lime which is formed by its action on the muriate of
lime. Real sulphate of lime, and real sulphate of soda, are

| 30 2 very

472 ANALYSIS OF THE

very nearly equivalent to each other with regard to the pro-
portions of their acid and base ; so that the quantity of the one
may nearly be substituted for that of the other ; 3.5 of sulphate
of lime being equal to 8.7 of sulphate of snd But this sul-
phate of lime is formed at the expence of a portion of muriate
of lime, and its formation is accompanied with the production
of a little muriate of soda ; hence the proportion of the former
must be a little larger, and that of the latter a little smaller,
than have been before stated. 3.5 grains of sulphate of lime
are equivalent to 2.8 of muriate of lime, which quantity, there-
fore, is to be added to the proportion above assigned. The
equivalent portion of muriate of soda to be subtracted is 3.
The whole proportions, therefore, will be the following :

Mnriate of soda, 2 Qi grains.
‘Muriate of lime, - 20.8
Sulphate of soda, —- 3.7
Carbonate. of lime, - 0.5
Oxide of iron, - 0.17
46.17

The quantity of sulphate of lime obtained in the analysis of
the Pitcaithly water, being so much smaller than that in the
Dunblane, it may perhaps be considered as an original ingre-
dient ; or if even the opposite view be adopted, the change in
the proportions, as indicated by the analysis, is much less.
They may be stated as follow :

Muriate of soda, : 12.7 grains.
Muriate of lime, — + (90.2
Sulphate of soda, - 0.9
Carbonate of lime, - 0.5

The

MINERAL WATERS OF DUNBLANE, 478

The carbonate of lime contained in both waters, may, it is —
obvious, according to the same view, be a product of the ope-
ration, and may exist in the water in the state of carbonate of
soda. Yet the quantity is so small, and carbonate of lime is
so generally diffused in the mineral kingdom, that it may per-
haps be regarded as an original ingredient. On the other hand,
it seems to be nearly insoluble in water, and this favours the
supposition that it is a product of the analysis. It is unques-
tionably so in the mineral waters in which it has been stated.
to exist in much larger quantity, and in which there is not, at
the same time, any excess of carbonic acid, by which it might
be retained dissolved.

The view of the constitution of this mineral water which I
_ have now explained, suggested a method of analysis which I
may state, both as it accords with, and in some measure con-
firms it, and illustrates some circumstances connected with the
mutual action of the sulphate of soda, and muriate of lime, to
which I shall afterwards have to refer. It affords, too, an ex-
cellent illustration of the definite proportions in which many
bodies combine, and the uniformity of results which are ob-
tained from their action on each other, in consequence of this
law. |

Supposing the sulphate of lime obtained from this water by
evaporation, to be formed by the action of sulphate of soda on
a portion of its muriate of lime, it might be inferred, that by
adding the due proportion of sulphate of soda, the whole mu-
riate of lime it contains may be converted into sulphate of
lime; and this, from its insolubility, being easily separated
from the muriate of soda, the quantity of it, and of course the
quantity of muriate of lime, will be ascertained. From the
preceding analysis, 18 grains of muriate of lime appear to exist
in a pint of the Dunblane water. Now this quantity requires

for

att ANALYSIS OF THE

for its decomposition 23.1 of real sulphate of soda; and the
products of this decomposition are 22.1 of real sulphate of
lime, and 19 of muriate of soda*. The former of these pro-
ducts being collected and dried, may be weighed, and the lat-
ter being deducted from the whole quantity of muriate of soda
obtained by evaporation, the remainder will be the quantity
originally contained in the water. The obtaining these quan-
tities, therefore, or near approximations to them, will be at
once a confirmation of the preceding analysis, and of the accu-
racy of these proportions.

A pint of the water was evaporated to about one-fourth ; the
quantity of real sulphate of soda required for the decomposi-
tion of its muriate of lime, it. has been just stated, is 23.1
grains. But, by previous trials, I had found, that a small ex-
cess of sulphate of soda renders the decomposition more com-
plete ; 24 grains, obtained by exposing crystallised sulphate
of soda to a red heat, were, therefore, added. The liquor soon
became turbid and thick. I had also found, that to render the
decomposition more complete, it is of advantage not to evapo-
rate at once to dryness, but to add small quantities of water
occasionally for some time during the boiling. The experi-
ment having been conducted in this manner, a precipitate of
sulphate of lime was collected, which, when washed and dried,
weighed 19 grains. The liquor being evaporated, afforded of
dry salt 51.6 grains. But on dissolving this salt in water, a
deposite of sulphate of lime remained undissolved; and even
on again evaporating to dryness, and re-dissolving in water, a
small portion was deposited for three successive times. The

whole

* The inspection of the scale of chemical equivalents, gives at once these
numbers ; and this highly useful instrument, lately invented by Dr Wotxasrton,
facilitates greatly all such researches, by the number of results it presents with-
eut the necessity of calculation.

MINERAL WATERS OF DUNBLANE. 475

whole quantity of sulphate of lime thus collected amounted to
5.8 grains, and of course incréased the former quantity of
19 to 24.8 grains. Supposing the quantity of sulphate of
lime originally contained in the water, or, what is the same
thing, capable of being produced, in its evaporation, from its
own ingredients, to amount to 3.8 grains, this leaves 21 grains
formed by the action of the sulphate of soda which had been
added on the muriate of lime; and this is equivalent to 17.1
grains of muriate of lime. The saline matter obtained by eva-
poration of the solution, weighed after exposure to a red heat
44.4 srains. Of this, supposing it to be all muriate of soda,
18 grains would be formed by the action of the sulphate of so-
da on the muriate of lime; and there remain 26.4 grains as the
quantity which the water had contained. This quantity is ra-
ther larger, and that of muriate of lime rather smaller than
what are obtained by the other analyses. But the saline matter
was found not to be entirely muriate of soda; its solution be-
came turbid on the addition both of muriate of barytes, and of
oxalate of ammonia, indicating the presence of sulphuric acid,
and of lime, either in the state of sulphate of lime, retained in
' solution, or of muriate of lime and sulphate of soda, remain-
ing undecomposed. An excess of sulphate of soda of 0.9
grain, it has already been stated, had been employed, which
reduces the weight of the salt to 25.5 grains; and if a little
more be subtracted on account of the lime it contained, and
be added to the muriate of lime, it will give proportions near-
ly the same as those before assigned; and the results by this
method. will thus correspond with those by the others.

Having stated this view of the composition of this water, I
have now to consider it under a more general light, and to
point

476 ANALYSIS OF THE

point out a few applications which follow from it, connected
with the chemical constitution of waters which contain simi-
Jaringred ien ts.

Sa neal

Sulphate of lime has been often stated as an ingredient ex-
isting in mineral waters, with muriate of soda, and muriate of
lime. It is almost superfluous to remark, that it is probable
the original ingredients, in all such cases, are sulphate of soda
and muriate of lime, and that the sulphate of lime is a product
of the operation, or rather, that the portion of it equivalent to
the quantity of muriate of soda, has this origin. |

It is a curious fact, which strongly confirms this, that in al-
most all the analyses of mineral waters since the time of Brrc-
MAN, when they can be presumed to have been executed with
any precision, where sulphate of lime is an ingredient, muri-
ate of soda is also present. It is obvious, that, if the sulphate
of lime has this origin, muriate of soda must also be formed.
On the other hand, in the greater number of those analyses
in which muriate of soda is an ingredient, we find also sulphate
of lime; and, with the exception of the water of Harrowgate,
sulphate of lime is always present, where muriate of soda and
muriate of lime are conjoined.

But the principal interest belonging to this view, is derived
from its relation to a question which has often been brought
under discussion,—Whether chemical analysis is capable of
discovering the sources of the medicinal virtues of mineral wa-
ters ? This question some have been disposed to decide in the
negative, from finding examples of waters possessed of active
powers, in which analysis does not detect any ingredients of

adequate activity.
On

MINERAL WATERS OF DUNBLANE. 477

‘On the general question, the remark by Dr Saunvens is per-
fectly just, that, “‘ consideting the comparative accuracy to
which chemists are at present able to carry their inquiries, we
can hardly suppose, that whatever slight error might occur in
the estimation of minute quantities, the actual existence of any
powerful agent on the human body, in any mineral water,
should escape the nicety of research.” Yet though this is just,
and though we can have no hesitation in rejecting the opinion
which would ascribe the medicinal qualities of mineral waters
to unknown or mysterious causes, or which would deny all
power to those in which an active chemical composition ‘can-
not be discovered, difficulties on this subject undoubtedly ex-
ist, and there is some room for that scepticism which has been
extended to this department of the Materia Medica.

Of this no better example can be given, than the cclebrated
Bath water. 1t has always been found difficult to account for
its powers, the ingredients which are obtained in its analysis
being substances of little activity, and the principal ones, in-
deed, being apparently inert. It contains in an English pint,
along with a slight impregnation of carbonic acid, about 9
grains of sulphate of lime, 3 grains of muriate of soda, 3 grains
of sulphate of soda, -£ths of a grain of carbonate of lime, ;th
grain of silica, and ;'th grain of oxide of iron. Now, from
these ingredients unquestionably no medicinal power of any
importance could be expected. They are either substances al-
together inert, or are in quantities so minute, as, in the dose in
which the water is taken, to be incapable of producing any
sensible effect. ‘Some have from this circumstance been dis-
posed to deny altogether any virtues to these waters ; but the
reverse of this appears to be established by sufficient evidence,
and what is still less equivocal, the injurious effects they some-
times produce, and the precautions hence necessary in their
use, sufficiently demonstrate their active powers. To account

Vou. VII. P. II. 3P for

478 ANALYSIS OF THE

for. these, therefore, various hypotheses have been proposed.
The observation has been urged, which, to a certain extent, is
undoubtedly just, that substances given in small doses in a
state of great dilution, may, from this: dilution, produce more
effect on the general system, than the quantity given would
lead us to expect. The temperature of the water, too, it has
been supposed, may have a considerable share in aiding the ef-
fect; and these two circumstances in particular, it has been
imagined, may favour the action of the iron. This is the view
of the subject given by Dr Saunners, in his Treatise on Mine-
ral Waters. Some of the other ingredients, too, it has been
supposed, may exert unknown powers. ‘Thus, some effect has
been ascribed to the agency of the nitrogen gas which rises
through the water. And Dr Saunvers himself, apparently
not very well satisfied with the reasoning he had employed,
allows some weight to the opinion suggested by Dr Grszes,
that the siliceous earth assists in the general effect of the Bath
waters ;—remarking, that.though there is only a grain of it in
half a pint of the water, this forms no objection, when the
great powers of very minute quantities of active substances are
considered ; that neither is its insolubility in the animal fluids
an. objection, as it exists.in the water in a state of solution;
and that though it has neither taste nor smell, it may be an
active substance, since there are indisputably powerful medi-
cines, which have little of either of these qualities.

All this, it is superfluous to observe, is extremely unsatisfac-
tory. With regard to the iron, the only active substance,—al-
lowing full weight to the observations, that small quantities of
active medicines, under great dilution, operate with increased
power, and that a high temperature may aid their operation on
the stomach,—still we cannot believe that one-sixtieth ofa grain,
the quantity in a pint of this water, can produce any import-

on ant

J

MINERAL WATERS OF DUNBLANE. 479

ant medicinal effect. And with regard to the other substan-
ces, the reasoning whence their possible operation has been
inferred, instead of removing the difficulty, rather places it in
a clearer ight.

The view of the constitution of mineral waters steted sees
enables us to assign to the Bath water a much more active che-
mical composition. There is every probability that muriate
of lime is its powerful ingredient. The principal products of
its analysis are sulphate of lime, muriate of soda, and sulphate
of soda. The proportion of sulphate of lime is such, that part
of it must pre-exist in the water, but part of it, there is reason
to conclude, is a product of the analysis ; the muriate of soda is
entirely so, and the quantity of sulphate of soda is larger than
what the analysis indicates. In other words, there exist in it
muriate of lime, sulphate of soda, and sulphate of lime, and
during the evaporation, the muriate of lime being acted on by
a portion of the sulphate of soda, muriate of soda and a cor-
responding portion of sulphate of lime are formed.

On the probability of this view, I need not, after the prece-
ding illustrations, offer any observations. The obtaining cer-
tain saline compounds from a mineral water by evaporation,
leads, no doubt, at first to the conclusion, that they are its in-
gredients ; it is the conclusion, accordingly, which has hither-
to been always drawn, and we are disposed to regard this as
evidence establishing this conclusion, in some measure, in op- ©
position to any different view of the composition. But this is
merely oversight or prejudice. If it can be shewn, that the ele-
ments of these compounds may equally exist in the water in a
different state of combination, which the evaporation must
change, the conclusion that they do exist in such a state is a priori
as probable, as the conclusion that they exist in the state in which
they are actually obtained. It is demonstrable, that if muriate
of lime and sulphate of soda exist in a mineral water, or, what

3P 2 is

480 ANALYSIS OF THE

is even less ambiguous, if they be dissolved together in pure
water, they must by evaporation be obtained, as muriate of so-
da and sulphate of lime. The actual obtaining, therefore, of
these latter compounds, is no proof that they pre-existed as
such in the water, to the exclusion of the opposite view.
Which conclusion is to be adopted, must be determined on
other grounds; and from the various facts I] have stated, I be-
lieve it may be regarded as the more probable opinion in such
cases, that the original ingredients are sulphate of soda and
muriate of lime. Since sulphate of soda exists in the Bath
water, and since muriate of soda and sulphate of lime are ob-
tained in its analysis, it is scarcely possible to refuse assenting
to the conclusion, that these are formed by the action of sul-
phate of soda on muriate of lime.

On this view of the composition of the Bath etd: it is
easy to assign the proportions of the ingredients, from the pro-
ducts which are obtained in its analysis. In the formation of
3.3 grains of muriate of soda, which is the quantity obtained
from a pint of the water, 3.1 grains of muriate of lime must be
decomposed: 4 grains of sulphate of soda would be required
to produce this decomposition ; and, at the same time, 3.8
grains of sulphate of lime would be formed.

The latest, and no doubt the most accurate analysis of the
Bath water, that by Mr Puituies, gives the following view of
its composition :

In-an English pint, Carbonic acid, - 1.2 inches.
Sulphate of lime, - 9 grains.
Muriate of soda, - 3.3
Sulphate of soda, - 15
Carbonate of lime, — 0.8 ©
Silica, - . 0.2
Oxide ofiron, = o> grain.

But

MINERAL WATERS OF DUNBLANE. 481

But considering the composition according to the preceding
view, the ingredients and their proportions will be.

Carbonic acid, - 1.2 inches.
Sulphate of lime, - 5.2 grains..
Muriate of lime, - 3:1,
Sulphate of soda, - 5.5;
Carbonate of lime, 0.8.
Silica, ©“. - - » 0.2.
Oxide of iron, - sr grain.

The peculiarity in the composition of the Bath water, com--
pared with the greater number of saline mineral waters, is,.
that it contains a larger quantity of sulphate of soda than is:
necessary to convert its muriate of lime into sulphate of lime..
Hence no muriate of lime is obtained after evaporation in-
its analysis ; hence even a portion of sulphate of soda is indi-
cated; and hence the large proportion of sulphate of lime.
which that analysis yields. In the Dunblane and Pitcaithly
waters, the sulphate of soda is deficient ; the muriate of lime
is in large quantity, and is accompanied with muriate of soda:
hence the entire want of sulphate of soda, the small quantity
of sulphate of lime, and the large proportion of muriate of lime.
_in their analyses.

Muriate of lime, it is well known, is a substance.of consider-
able power in its operation on the living system; in quantities
which are even not large, it proves fatal to animals. When
taken to the extent of six grains, the quantity of it. which, ac-
cording to the preceding view, exists in a quart of the Bath
water, it cannot be inactive. It is very probable, too, that a
given quantity of it will prove much more active in a state of
great dilution in water, than in a less diluted form ; as, in this

diluted

482 ANALYSIS OF THE

diluted state, it acts, when received into the stomach, over 4
more extended surface ; and, besides this, whatever eflect- may
be due to the high temperature of the Bath water, in aiding
the operation of the minute portion of iron it contains, the
same effect must be equally obtained in aiding the operation
of the much larger quantity of muriate of lime. The conclu-
sion, indeed, as to the importance of this effect, is much more
probable with regard to the muriate of lime, than to the iron ;
for supposing the quantity of the former to exist in the Bath
water, which has been assigned, the dose of it taken in a quart
of the water, is not far from its proper medium dose, and is at
least equal to one-half the largest dose which can be given,
and continued without producing irritation ; while the dose of
the iron is not the one-hundredth of that which is usually pre-
scribed. Under the circumstances, therefore, in which the
muriate of lime is presented in the Bath water, it is reasonable
to infer that it must be ap ini of considerable immediate
effect.

The speculation is farther not improbable, that, to produce
its more permanent effects on the system as a tonic, it is ne-
cessary it should enter into the circulation. In a dilute state
of solution, it may pass more easily through the absorbents ;
while, in a more concentrated state, it may be excluded, and
its action confined to the bowels. Hence the reason, perhaps,
that in some of the diseases in which it is employed, scrofula
particularly, it has frequently failed, its exhibition having been
in doses too large, and in too concentrated a form. And hence
it is conceivable, that in a more dilute state, as that in which
it may exist in the Bath water, besides its immediate opera-
tion, it may produce effects as a permanent tonic, more import-
ant than we should otherwise expect *.

I

* I may mention in confirmation of this, that I found a mineral water of
considerable celebrity in Yorkshire, that of Ilkley, and which in particular was
held

MINERAL WATERS OF DUNBLANE. 483

I may add, that the iron in the Bath water is probably not
in the state of oxide or carbonate, as has been supposed, but
in that of muriate. The muriate is the most active prepara-
tion of iron, and so far, increased activity may be given to the
slight chalybeate impregnation; and some modification of
power may even be derived from the combined os Silat of
muriate of lime and mufiate of iron.

It deserves to be remarked, that in the most essential ingre-
dients, the muriate of lime and the iron, the Dunblane and
Pitcaithly waters are similar to the Bath water, only with re-
gard to the former ingredient much stronger ; the other differ-
ences are unimportant ; the larger quantity of sulphate of lime,
and the small quantity of silica in the latter, cannot be suppo-
sed to contribute any thing to its medicinal operation ; the dif-
ference in the proportion of sulphate of soda is trivial, and the
larger proportion of muriate of soda in the other waters, may
rather be an advantage, rendering them more agreeable-to the
taste and to the stomach. The principal difference will there-
fore be that of strength with regard to the most active ingre-
dient, the muriate of lime. The quantity of this is so large,
that the tonic quality of the Dunblane or the Pitcaithly waters
can scarcely be observed, and perhaps even scarcely obtained ;
their action being more peculiarly on the bowels. It. is ac-
cordingly as a saline purgative that the Pitcaithly water has
been celebrated; and it is principally in those diseases in
which this effect is sought to be obtained, that it has been

used.

‘held in high estimation as a remedy in scrofulous affections by several
“eminent medical practitioners, to be water uncommonly free from all foreign
“matter, with the exception of very minute quantities of muriate of soda, and
amuriate of lime. I had the.opportunity of observing, at the same time, proofs
of its medicinal efficacy.

A484 ANALYSIS OF THE

used. The Dunblane water, from the similarity of its opera-
tion, would no doubt be employed in diseases of a similar
kind. But whatever advantage might be derived from this
purgative effect, it cannot fail to be perceived, that a different
operation, not less useful, may be obtained from them. If suf-
ficiently diluted, so as to avoid altogether the operation on the
bowels, the stimulant operation on the stomach and general
system might be exerted by these waters, similar to that of the
Bath waters, and under this form they might prove useful in
diseases very different from those in which they might other-
wise be-employed. As they would require, too, large dilution
to reduce them to this state, the temperature of the Bath wa-
ter might easily be given, by adding the requisite proportion
of hot water, by which a greater similarity of operation would
be obtained. And the Dunblane water in particular, contain-
ing so much larger a proportion of iron than the Bath water
does, the dilution requisite to give it the same strength, with
regard to the muriate of lime, would still leave an equal degree
of chalybeate impregnation. If the preceding observations,
therefore, are just, the Dunblane and Pitcaithly waters may be
converted, in all the essential parts of the chemical composi-
tion, into a water similar to that of Bath. -

From the preceding statement of their composition, it is ea-
sy to discover how this may be done. To give the same pro-
portion of the principal ingredient, the muriate of lime, the
Dunblane water would require to be diluted with from six to
seven parts of pure water; the same degree of dilution would
bass it to nearly the same strength with regard to the iron ; if

a pint of it were diluted with this portion of water, about 35
grains of sulphate of soda would require to be added, to ren-
der the composition, with regard to this ingredient, perfectly
alike, if this were thought elbcHGu The waly remaining dif-

ferences

“aT * BA

MINERAL WATERS OF DUNBLANE, 485

ferences would then be, the presence of abcut 2.8grains of
muriate of soda in each pint of the reduced Dunblane water,
the deficiency of 5.5 grains of sulphate, and 0.7 grain of car-
bonate of lime, and the absence of 0.2 grain of siliceous earth,
differences in all respects probably of no importance whatever.
The simple expedient, indeed, of diluting one part of the Dun-
blane water with from six to seven parts of warm water, (or if
the sulphate of lime in a state of solution should be supposed
to be possessed of any active power, with four or five parts)
and adding, if the chalybeate impregnation were not found suf-
ficiently active, a few drops of tincture of muriate of iron,
awould probably serve every purpose. And if sufficient confi-
dence could be given to the substitution on the part of those
employing these waters medicinally, the Dunblane water, thus
altered, might probably be taken with as much advantage as
the Bath water in the diseases in which it has been found use-
ful. !

It is obvious, too, that if the artificial preparation of the
Bath water were attempted, it could be done much more easi-
ly according to this view, than by endeavouring to dissolve the
actual products of its analysis, which, indeed, it would be im-
practicable to do. Muriate of*lime, and sulphate of soda, dis-
solved in water of the due temperature, with the addition of a
minute portion of muriate of iron, would probably afford a
composition approaching as nearly to the natural composition,
as is either practicable or necessary in the imitation of any mi-
neral water. | oft

A similar view may be taken of the composition of Chelten-
ham water. Its analysis affords sulphate of soda, sulphate of
magnesia, and sulphate of lime, with muriate of soda, muriate
of magnesia, carbonate of magnesia, and oxide of iron. There
is no just reason, however, to infer with certainty, that all
these are its real ingredients. It is as probable, and, indeed,

Vor. VII. P. II. 3 Q more

486 , ANALYSIS OF THE

more so, that, previous to the evaporation by which they are
obtained, it contains muriate of lime, which being acted on by

the sulphate of soda, forms muriate of soda, and sulphate of

lime. It is even not improbable, that the carbonate naturally
existing in the water, is not carbonate of magnesia, but carbo-
nate of soda, which, re-acting,. from the concentration by the
evaporation, on sulphate or muriate of magnesia, causes the
production of the carbonate of magnesia with a corresponding
portion of sulphate or muriate of soda; or, what is equally pro-
bable, and presents the same ultimate results, the sulphate of
magnesia may, in the progress of the evaporation, be first act-
ed on, by the carbonate of soda, forming carbonate of magne-
sia and sulphate of soda; and the sulphate of soda, during the
farther concentration, may act on the muriate of lime, and
form muriate of soda, and sulphate of lime. It is much more
probable, indeed, from the known insolubility of carbonate of
magnesia, that it is produced in this way, than that it should
exist in a state of solution in so large a quantity, as that in
which it is afforded by the evaporation. And thus this. water
will present a striking example, that the real ingredients of a
mineral water, and their proportions, may be very different
from those obtained by the direct analysis ; for it is too obvi-
ous, after the preceding observations, to require illustration,
that the actual production of certain ingredients by evapora-
tion, or any other analytic process, is no certain proof that
they pre-existed in the water. It is obvious, too, that if it
were proposed to imitate the Cheltenham water by artificial
preparation, it could be done much more easily according to
this view,than by attempting to dissolve the ingredients obtained
by the analysis, an attempt, indeed, which would not succeed.
The Dunblane or Pitcaithly water might be converted, so far
as regards the saline ingredients, into a water similar to that of

Cheltenham,

MINERAL WATERS OF DUNBLANE. 487

Cheltenham, by the addition of a little sulphate of magnesia,
or more nearly, by the addition of a little of the bittern of sea
water ; aud where in the use of these waters, a continued pur-
gative operation is required, such an addition might always be
made with advantage. They might even be made to receive
the impregnation of carbonic acid of the Cheltenham water,
by adding the magnesia in the state of carbonate, with'the due
proportions of sulphuric and muriatic acids in a close ves-—
sel.

The water of Harrowgate affords in its gaits ingredients
another illustration of the same views. The principal ingre-
dient is muriate of soda, with which are present muriate of
magnesia, muriate of lime, sulphate of magnesia, carbonate of
magnesia, and carbonate of lime. Now nothing is more pro-
bable, than that the two last substances are not original ingre-
dients, but are products of the analysis formed by the action
of carbonate of soda existing in the water on portions of its
muriate of magnesia and muriate of lime, whence also the
quantity of muriate of soda is increased.

Lastly, A similar view may be extended to some of the most
celebrated foreign mineral springs. Those of Spa, Pyrmont,
and Seltzer form a very valuable order of mineral waters, to
which we have none analogous in this country ;—what have been
called the alkaline eaiienated waters, distinguished by the
leading character of being largely impregnated with carbonic
acid gas, and containing a considerable proportion of carbonate
of soda. With this are associated carbonate of magnesia, car-
bonate of lime, and muriate of soda. Now this association of
muriate of soda with these earthy carbonates, while there is al-
so carbonate of soda present,-leads almost necessarily to the
belief, that the real ingredients are carbonate of soda, muriate
of magnesia, and muriate of lime; that the carbonate of soda

3Q 2. is

433. ANALYSIS OF THE

is in larger proportion than what is indicated by the analysis ;
that it acts during the evaporation of the water on the muri-.
ates of magnesia and lime, and forms the carbonates of these.
earths which are obtained with corresponding portions of mu-.
riate of soda; and that it is only what muriate of soda there
may be above this, that exists as an original ingredient.

. The Seltzer water, which is the purest of this order of wa-
ters, as containing neither iron, nor any sulphate, affords in
particular a very excellent illustration of this. It contains,
according to, BereMan’s analysis, in an English pint,

Carbonic acid gas, - 17 cubic inches.
Carbonate of lime, - 3 grains.
Carbonate of magnesia, 5

Carbonate of soda, _—- 4 ——

Muriate of soda, » | he i

But adopting the opposite view, the composition, so far as.
the uncertainty of the state of the products, to which Berce-.
MAN’S estimate is referred, admits of calculating the propor-.
tions, will be,

Carbonic acid gas, - 17 cubic inches..

Muriate of lime, - 3.3 grains.

Muriate of magnesia, - 5

Muriate. of soda, - 7.8

Carbonate of soda, - 10.3. —dry, or 18 crystallised *.

It

* The following is the calculation from which these proportions are assigned.
Three grains of carbonate of lime are equivalent to 3.3 of real muriate of lime :
5 grains of carbonate of magnesia, in the state in which it was obtained by.

Bercman, that is, the powder precipitated and dried, are equivalent to 5 grains
of.

MINERAL WATERS OF DUNBLANE. 483

It might be supposed, that so large a proportion of carbo-
nate of soda, could not exist with the muriates of magnesia
and lime without decomposing them ; that this view of the
constitution of this water is therefore precluded; and that
Bereman’s is just. And, in this case, the non-precipitation of
the carbonates of magnesia and lime, may be supposed to be
owing to the solvent power of the excess of carbonic acid ;
to which cause, accordingly, it has been ascribed. But on ma-
king the experiment, I found that the above quantities might
_be dissolved in a pint of water, independent of the presence of
the excess of carbonic acid, without any apparent decomposi-
tion ; the solution being transparent, and remaining so on ex-
posure to the air. The same fact has even been observed with:
regard to the natural water ; for although on exposure to the
air it becomes vapid, and its taste is merely sensibly alkaline,
the carbonates are not precipitated; the precipitation takes.
place only when heat is applied, so“As to:evaporate the water
to a certain extent. And with regard to this, a fact is men-
tioned by. Bercman not less conclusive. The carbonate of
lime is first deposited, with scarcely any mixture of carbonate
-of magnesia; the latter separates only by continued evapora-
tion; and it is even necessary to evaporate to dryness, and re-
dissolve in hot water, to obtain it entirely,—proving that it

does

of real muriate of magnesia. In converting the first of these muriates into car-
bonate, 3.2 grains of dry common carbonate, or sub-carbonate of soda, would be
expended ; and in the conversion of the second muriate, 5.7 grains, making 8.9.

grains, to which are to be added 1.4 grain, the quantity contained in the 4
grains of the crystallised carbonate obtained as the direct product of the analy-
sis, making in all, as stated above, 10.3 grains, Lastly, in these decompositions:
of the earthy muriates, 9.7 grains of muriate of soda would be formed, which,.
deducted from the 17.5 obtained in the analysis, leaves 7.8 as the quantity which.,
the water really contains.

490 ANALYSIS OF THE

does not pre-exist in the water, dissolved by an excess of car-
bonic acid, but that it is produced during the evaporation, and
_ must therefore be formed by the action of carbonate of soda on
muriate of magnesia.

This view of the composition of this water, accords much
better than the other, both with its sensible qualities, and its
medicinal powers. Its taste, after the carbonic acid has esca-
ped from it, on exposure to the air, is rather strongly alkaline,
which would scarcely be the case, if it contained only four grains
-of crystallised carbonate of soda in a pint, but which is to be
expected if it contain eighteen grains. It operates as an antacid
and diuretic, and is productive of much benefit in all dyspep-
tic affections, in diseases of the urinary organs, and in those
general affections of the system which require a mild tonic
power. There are few mineral waters, Dr Saunpers observes,
which have acquired a higher reputation; and there are few,
he adds, that deserve gréater consideration, from the real me-
dicinal virtues it possesses. It will be difficult to give a satis-
factory account of the origin of these virtues, if we regard it as
water impregnated with carbonic acid, holding in solution so
minute a portion of carbonate of soda, with the larger propor-.
tions of muriate of soda and carbonates of magnesia and lime.
But if we consider it as containing along with its free carbo-
nic acid, a considerable quantity of carbonate of soda, with
smaller proportions of muriate of soda, muriate of magnesia,
and muriate of lime, we assign to it a composition of much
greater power, and adequate to account for the effects it produ-
ces. Such is the activity of this water, that its medium dose is
only half an English pint, a degree of power which accords
much better with the one view of its composition than with the
‘other *.

Large

* The water of Malvern may be regarded as of similar composition, only

much

MINERAL WATERS OF DUNBLANE... 491.

Large quantities of Seltzer water have been imported into-
this country, and artificial preparations of it are in frequent
use. If these are founded on Bercman’s view of its composi--
tion, they can scarcely succeed ; probably, therefore, this is not:
attempted. The view which I have suggested, renders its ar-
tificial preparation much more easy. ‘The ingredients may be
dissolved in water, and the solution impregnated with carbo-.
nic acid gas. Or, what is easier, these steps of the process
may be conjoined. The muriate of lime may be formed by
adding the requisite quantity of carbonate of lime to the due
proportion of muriatic acid diffused in water, and the vessel.
being closed, the escape of the carbonic acid gas miay be pre-
vented. The muriate of magnesia, and the muriate of soda,
may be formed in a similar manner from the carbonates of |
magnesia and soda. And the quantity of carbonic acid thus
afforded, will be very nearly that which is required. To form.
the muriate of lime, 3 grains of carbonate are to be used ;.
to form the muriate of magnesia, 5 grains of the carbonate of |
that earth ; and to form the 7.8 grains of muriate of soda, 12.3

grains:

much weaker, and without any free carbonic acid. Dr Witson’s analysis gives.
the following ingredients, and their proportions in a gallon:

Carbonate of soda, - 5.33 grains.
lime, - 1.6
——— magnesia, - 0.9199
iron, - 0.625
Sulphate of soda, = 2.896 ©
Muriate of soda, - 1.553 |
Residuum, - - 1.687 .

The muriate of soda, there is every probability, is.a product of the operation,..
formed by the action of carbonate of soda on muriate of lime; or if sulphate of
lime formed part of the residuum, as is. probable, by the action of sulphate of.
soda on muriate of lime,

492 ANALYSIS OF THE

>

grains of crystallised carbonate of soda. These quantities con-
tain 6.2 grains of carbonic acid, or 13 cubic inches, a quantity
not much beneath that which the Seltzer water contains. The
neutral carbonate of soda, or bi-carbonate, as it is named, may
even be substituted in the preparation ; and if the due propor-
tion of this be used. (11 grains), it will yield 6 cubic inches
additional, making the whole quantity 19 cubic inches, 2 more
than the quantity in the water *.

I might apply the same view to a number of other analyses
of mineral waters, even the most recent. But though this —
would not be altogether uninteresting, it is scarcely necessary to
extend the illustration farther. The general conclusion may,
I believe, be drawn, that in the analysis of saline mineral wa-
ters, the actual products of the analytic operation are not al-
ways to be regarded as the real ingredients. A different
view of the composition is often to be taken, and may in
many cases be applied, so as to afford a more satisfactory solu-
tion of their active powers.

I may only farther remark, that a view somewhat different
may also be applied, founded on the doctrine, that the prima-
ry ingredients of the compound salts, obtained by the analysis
of mineral waters, are in-simultaneous combination, and not in

’ the

* The following is the easiest method of conducting the process. About 35

‘grains of muriatic acid, of the strength usually met with in the shops, are put
‘into a strong bottle with a pint of water; the acid being introduced at the bot-
tom of the water by along funnel. Three grains of pure white marble, in
coarse powder, are dropt in, and the bottle is closed. When these are dissolved,
5 grains of the common carbonate of magnesia in powder are added, and after
the solution of this, 32 grains of crystallised carbonate of soda, or, what is equi-
valent to this, and preferable, as affording more carbonic acid, 27 grains of bi-
carbonate of soda, are put in. The bottle is closed accurately, shaken, and in.
verted. In a short time a perfect solution takes place, and a liquor is obtained
transparent, which sparkles when poured out, and has a pleasant taste.

MINERAL WATERS OF DUNBLANE. 493

the state of binary compounds. Even this view, were it adopt-
ed, would afford a better explanation of their active powers,
than the view of their composition which is usually received,
since it could not at least be affirmed, that such a combination
must be inactive. The opinion itself, however, is much less
probable ; for if fairly followed out, it leads to the conclusion,
that all combinations of compound bodies are simultaneous
combinations of the primary elements,—a conclusion from
which no inference with regard to specific qualities could be
drawn, and which is inconsistent, therefore, with the conclu-
sions which in many cases we are able actually to form. We
are led, therefore, to the admission, that the state of binary
combinations exists ; and it is only necessary to guard against
the error of supposing that the Se aa of the analysis are al-
ways the original ingredients..

The importance of the subject, and its relation to the ques-
tion, how far chemical analysis is capable of accounting for the
medicinal efficacy of mineral waters, will, I hope, afford an.
apology for the introduction of some of the preceding observa-
tions, though they may not fall strictly under the objects usu--
ally submitted to the Society..

In a succeeding paper, I shall have to. offersome remarks on
the analysis of Sea-water, and salt brines, suggested by the view:
which I have explained in this. And the same view may per-
haps lead to the illustration of a geological problem, hitherto
involved in considerable difficulty, the origin of Rock Salt,
and the relation of this mineral to the saline impregnation of
the ocean.

Vou. VIL P.IL 3R ; : XVI.

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XVII. Biographical Account of the late Youn Rosison, LL. D.
F.R.S. Epi. and Professor of Natural Philosophy:
in the University of Edinburgh. By Joun Piayrair,
FE.R.S.L. & E. &c..

(Read 20th February 1815.)

"JHE distinguished: person who is the subject of this me-

moir, was born at Boghall, in the parish of Baldernock,,

near Glasgow, in the year 1739.. His father, Jonn Rosison,.

had been early engaged: in commerce in Glasgow, where, with.

a character. of great probity and worth, he had acquired consi-.

derable wealth, and, before the birth of his son, had retired to»
the country, and lived at his estate of Boghall.

His son was educated at the grammar school of GJasgow..
We have no accounts of his earliest acquirements, but must sup--
pose them to have been sufficiently rapid, as he entered a stu-
dent of Humanity, in the University of Glasgow, in. Novem-
ber 1750, and in April 1756 took his degree in Arts..

Several Professors of great celebrity adorned that Universi-.
ty about this period. Dr Srmson.was one of the first geome-
ters of the age; and Mr Apam Smiru had just begun to ex-
plain in his lectures those principles which have since been de-.

3K 2 livered:

496 BIOGRAPHICAL ACCOUNT

livered with such effect in the Theory of Moral Sentiments,
and in the Wealth of Nations. Dr Moore was a great master
of the Greek language, and added to extensive learning a
knowledge of the ancient geometry, much beyond the acquire-
ment of an ordinary scholar.

Under such instructors, a young man of far inferior talents
to those which Mr Rostson possessed, could not fail to make
great advancement. He used, nevertheless, to speak lightly
of his early proficiency, and to accuse himself of want of appli-
cation, but from what I have learnt, his abilities and attainments
were highly respected by his cotemporaries, and he was re-
marked at a very early period for the ingenuity of his reason-
ings, as well as the boldness of his opinions. According to his
own account, his taste for the accurate sciences was not much
excited by the pure Mathematics, and he only began to at-
tend to them, after he discovered their use in Natural Philo-
sophy.

In the year following that in which he took his degree,
Dr Dick, who was joint Professor of Natural Philosophy
with his father, died, and Mr Rosison offered himself to the
old gentleman as a temporary assistant. He was recommend-
ed, as I have been told, by Mr Smrru, but was nevertheless
judged too young by Mr Dick, as he was not yet nineteen.
The object to which his father, a man of exemplary piety,
wished to direct his future prospects, was the Church, to
which, however, he was at this time greatly averse, from
motives which do not appear; but certainly not from any
dislike to the objects or duties of the Clerical Profession. It
was very natural for him to wish for some active scene, where
his turn for Physical, and particularly Mechanical Science,
might be exercised, and the influence of those indefinite and
untried objects, which act so powerfully on the imagination

of

OF THE LATE PROFESSOR ROBISON. 497

of youth, directed his attention toward London. Professor
~Dicx and Dr Stimson joined in recommending him to Dr
Brarr, Prebendary of Westminster, who was then in search of
a person to go to’sea with Epwarp, Duke of York, and to as-
sist his Royal Highness in the study of Mathematics and Na-
vigation. When Mr Rosison reached London in 1758, he
learnt that the proposed voyage was by no means fixed, and
after passing some time in expectation and anxiety, he found
that the arrangement was entirely abandoned. This first dis-
appointment in a favourite object could not fail to be severely
felt, and had almost made him resolve on returning to Scot-
land. —

He had been introduced, however, to Admiral Know .es,
whose son was to have accompanied the Duke of Yorx, and
the Admiral was too conversant with Nautical Science, not to
discover in him a genius strongly directed to the same ob-
jects. Though the scheme of the Prince’s nautical education
was abandoned, the Admiral’s views with respect to his son
remained unaltered, and he engaged Mr Rosison to go to sea
with him, and to take charge of his instruction. From this
point it is, that we are to date his nautical as well as scien-
tific attainments. |

About the middle of February 1759, a fleet sailed from
Spithead under the command of Admiral Saunprrs, intended
to co-operate with a military force which was to be employed,
during the ensuing summer, in the reduction of Quebec.
Young Knowrzs, whom Mr Rosison had agreed to accompa-
ny, was a midshipman on board the Admiral’s ship, the Nep-
tune of 90 guns; but in the course of the voyage, being pro-
moted to the rank of Lieutenant in the Royal William of
$0 guns, Mr Rosison went with him on board that ship,
and was there rated as a midshipman.

The

498 BIOGRAPHICAL ACCOUNT.

The fleet arrived on the coast of America in April; but it
was not till the beginning of May that the entire dissolution
of the ice permitted it to ascend the River St Lawrence, and
that the active scene of naval and military operations com-
menced, which terminated so much to. the ‘credit of the Bri-
tish arms. A person whose seafaring life was to be limited to
two years, may well be considered as fortunate, in witnessing,
during that short period, a series of events.so remarkable as.
those which preceded and followed the taking of Quebec.
Though great armies were not engaged, much valour and con-
duct were displayed; the leaders on both sides were men of
spirit and talents; and, on the part of the English, the most
cordial co-operation of the sea and land forces was worthy of
men animated by the spirit of patriotism, or the love of glory ;
the fate also of the gallant Leader, who fell in the moment of
victory, and in the prime of life, by repressing the exulta-.
tion of success, gave a deeper interest to the whole transac-
tion.

Of the operations of this period Mr Rosison was by no
means a mere spectator. A hundred seamen, under the com-
mand of Lieutenant Know es, were drafted from the Royal
William into the Stirling Cade: the Admiral’s ship. Mr Ro-
BISON was of this party, and had an opportunity of seeing a.
great deal of active service. At this time, also, he was occa-
sionally employed in making surveys of the river and the ad-
jacent grounds; a duty for which he was eminently qualified,
both by -his skill as a mathematician, and his execution as a
draughtsman.

It is, however, much to be regretted, that his papers, whe-
ther memorandums or letters, give no account of the incidents
of this period; so that we are left to conclude, from the history
_of the times, what were the events in which he must have ta-

ken,

OF THE LATE PROFESSOR ROBISON» 499

ken part, or to gather, from the imperfect recollection of his
conversation, the scenes in which he was actually engaged. I
have heard him express great admiration at the cool intrepi-
dity which he witnessed, when the fire-ships, sent down the
stream against the English navy, at anchor in the river, seem-
ed to present a wall of fire, extending from one bank to ano-
ther, from which nothing that floated on the water could
possibly escape. Without the smallest alarm or confusion,
the British sailors assailed this flaming battlement in their
boats, grappled the ships which composed it, and towed them
to the shore, where they burnt down quietly to the water’s
edge.

An anecdote which he also used to tell, deserves well to
be remembered. He happened to be on duty in the boat
in which General Wotre went to visit some of his posts, the
night before the battle, which was expected to be decisive of the
fate of the campaign. The evening was fine, and the scene,
considering the work they were engaged in, and the morning
to which they were looking forward, sufficiently impressive.
As they rowed along, the General, with much feeling, repeat-
ed nearly the whole of Gray’s Elegy, (which had appeared not
long before, and was yet but little known,) to an officer who sat
with him in the stern of the boat; adding, as he concluded,
that “ he would prefer being the author of that poem to the
“ glory of beating the French to-morrow.”

To-morrow came, and the life of this illustrious soldier was
terminated, amid the tears of his friends, and the shouts of his
victorious army. Quebec fell of course ; and soon afterwards
the fleet under Admiral SaunpeERs, sailed for England. When

they arrived on the coast, they were informed that the Brest
fleet was at sea, and that Sir Ep>warp Hawke was in search of
it. Without waiting for orders, Admiral SaunpeRs sailed to
reinforce Hawke, but came too late, the celebrated victory

over

500 BIOGRAPHICAL ACCOUNT

over ConFLans, in Quiberon Bay, having been obtained (on
the 20th of November) a few days before he joined. Whether
the Royal William accompanied the rest of the fleet on this
occasion, I have not been able to learn. The body of General
Wo re was brought home in that ship, and was landed at
‘Spithead, on the 18th of November. From that date to the
beginning of next year, I find nothing concerning the Royal
William, when that ship, with the Namur and some others,
under the command of Admiral Boscawen, sailed on an ex-
pedition to the Bay of Quiberon. On this service the Royal
William remained between five and six months, having been
twice sent to cruise off Cape Finisterre, for five weeks each
time.

About this period, a series of letters from Mr Rosison to
his father begins; and though the letters do not enter much
‘into particulars, they leave us less at a loss about the remain-
ing part of his seafaring life.

On the 3d of August the Royal William returned to Ply-

mouth, the greater part of the crew being totally disabled by,
the sea-scurvy, from which Mr Rosison tatiana slabin suffered very
severely. He writes to his father, that, out of seven hundred
and fifty able seamen, two hundred and eighty-six were confined
to their hammocks, in the most deplorable state of sickness and
debility, while one hundred and forty of the rest were unable
to do more than walk on deck. This circumstance strongly

marks, to us, who have lately witnessed the exertions of Bri-
tish sailors, in the blockade of Brest, and other ports of the
enemy, the improvement made in the art of preserving the
health of seamen within the last fifty years. The Royal
William, notwithstanding the state of extreme distress to
which her crew was reduced, by a continuance at sea, of hard-
~ ly six months, was under the command of Captain Hucx

Vic | Preavrsy

OF THE LATE PROFESSOR ROBISON. 501

Pscorr, one of the most skilful officers of the British navy. Mr
Rosson, indeed, never at any time mentioned his name with-
out praise, for nis knowledge of seamanship, and the ad-
dress with which he used to work the ship, in such bad
weather, as rendered her almost unmanageable to the other of-
ficers. The art of preserving the health of the seaman, is a
branch of nautical science which had at that time been little
cultivated. Our great Circumnavigator had not yet shewn,
that a ship’s crew may sail round the globe, with less mortali-
ty than was to be expected in the same number of men, living
for an equal period i in the most healthful village of their native
bor al
Mr Rosison’s letters to his father, about this iihien are
strongly expressive of his dislike to the sea; and of his resolu-
tion to return to Glasgow, and to resume his studies, particular-
ly that of Theology, with a view of entering into the Church.
These resolutions, however, were for the present suspended,
by a very kind invitation from Admiral Know rs, to come
and live with him in the country, and to assist him in his ex-
periments: “ Thus, (says the Admiral), we shall be useful to
“« one another.” What these experiments were, is not men-
tioned, but they probably related to ship-building, a subject
which ie Admiral had studied with great attention. Mr Ro-
accordingly, continued to enjoy a situation, and an em-
t, that must, both, have been extremely agreeable to
him, till the month of February in the year following, when
Lieutenant KNowLes was appointed to the command of the
Peregrine sloop of war, of 20. guns. Whether the plan of nau-
tical instruction, which Mr Roszison proposed for his pupil,
was not yet completed, or whether he had, after all, come to
a resolution of pursuing a seafaring life, (of which there is an

appearance in some of his letters), he embarked in the Pere-
Vox. VII. P. ID. 38 erine,

502 BIOGRAPHICAL ACCOUNT

grine, and he even mentions his hopes of being made purser
to that ship. The first service in which Captain KNowLes was
employed, was to convoy the fleet to Lisbon. In a letter from
Plymouth, where they were forced in by the weather, Mr
Rosison paints, in strong colours, the difference between sail-
ing in’ a small ship, like the Peregrine, and a first rate, like
the Royal William, and the uncomfortable situation of all on
board, during a gale which they had experienced in coming
down the Channel. The voyage, however, gave him an op-
portunity of visiting Lisbon, on which the traces of the
Earthquake were yet deeply imprinted ; and the ship con-
tinuing to cruise off the coast of Spain and Portugal, he
had occasion to land at Oporto, and other places on the Portu-
guese coast. In the month of June he returned to England ;
and from this time quitted the navy, though he did not give
up hopes of preferment. He returned, to live with Admiral
Kwowtes, and in the end of the same summer, was recom-
mended by him to Lord Anson, the First Lord of the Admi-
ralty, as a proper person to take charge of Harrison’s Time-
keeper, which, at the desire of the Board of Longitude, was to
be sent, on a trial voyage, to the West Indies.

The ingenious artist just named, had begun the construction
of his chronometer, on new principles, as éarly as the year |
1726, and with the fortitude and patience characteristic of ge-
nius, had for thirty-five years struggled against the physical
difficulties of his undertaking, and the still more discouraging
obstacles which the prejudice, the envy, or the indifference of
his cotemporaries, seldom fail to plant in the way of an inven-
tor. Notwithstanding all these, he had advanced constantly
from one degree of perfection to another, and it was his fourth
time-keeper, a to a portable size, and improved in all

~ other

OF THE LATE PROFESSOR ROBISON. 503

other respects, that was now. submitted to examination. It -
was intended that Mr Rosison should accompany young Har-
Rison and the time-keeper, in a frigate, the Deptford, to Port
Royal in Jamaica, in order to determine, on their landing, the
difference of time, as given by the watch, and as found by as-
tronomical observation. The time-keeper, accordingly, was
put into the hands of Mr Roszrrson, of the Naval School at
Portsmouth, who determined its rate, from nine days that it
remained in his custody, to. be 23% slow, per day, and also,
the error to. be 3°: slow, on the 6th of November, at noon,
according to mean solar time.

_ The Deptford sailed on the 18th of November, and arrived
_at Port Royal on the 19th of January; on the 26th, Mr Roz1-
son observed the time of nogn, and found it to answer to
4» 59™- 73: by the watch, and this being corrected for the er-
ror of three seconds, and also for the daily accumulation of
2+ for eighty-one days five hours, the interval between the
observations, the difference of longitude between Portsmouth
and Port Royal. came out 5" 2" 47%: only four seconds less
than it was known to be from other observations.

_ The instructions of the Board farther required, that, as soon
as an opportunity could be found, the same two gentlemen
should return with the watch to Portsmouth, that, by a com-
_parison of it with the time there, the total error, during
‘both voyages, might be ascertained. The opportunity of re-
turn occurred sooner than they had any reason to expect; for
the Spanish war having now broke out, an alarm of an inva-
sion of Jamaica from St Domingo, occasioned the Governor to
dispatch the Merlin sloop of war to England, to give intelli-
gence of the danger. Mr Rozison and Mr Harrison obtain-
ed leave to return in the Merlin, and sailed on the 28th, ha-
ving been but a few days in Jamaica. This voyage was an

288 epitome

504 BIOGRAPHICAL ACCOUNT

epitome of all the disasters, short of shipwreck, to which sea-
faring men are exposed. ‘They experienced a continuation of
the most tempestuous weather, and the most contrary winds,
from the moment they quitted the Bahamas, till they arrived
at Spithead. To add to their distress, the ship sprung a great
leak, three hundred leagues from any land, and it required the
utmost skill and exertion to keep her from sinking. In a ter-
rible gale, on the 14th of March, their rudder broke in two,
so that they could no longer keep the ship’s head to the wind,
and if the gale had not speedily moderated, they must inevi-
tably have perished. When the voyage was near a conclusion,
and they were congratulating themselves on the end of their
troubles, the ship was found to be on fire, and the flames were
extinguished with great difficulty. They reached Portsmouth
on the 26th of March, and on the 2d of April the mear noon
by the watch was found to be at 11" 51™ 313", and, making
correction for the error and rate, this amounted to 11" 58™ 63s,
so that the whole error, from the first setting sail, was only
1™ 534°, which, in the latitude of Portsmouth, would not
amount to an error, in distance, of twenty miles.

When Mr Rosison undertook the voyage to Jamaica, he
made no stipulation for any remuneration, and Lord-ANnson
assured him, that he should have no reason to repent the eon-
fidence which he placed in the Board. But when, on his re-
turn, he came to look for the reward, to which the success and
trouble of the undertaking certainly entitled him, he soon
found that he had’ greatly dina, in: leaving himself so much at
the mercy of unforeseen contingencies. Lord Anson was ill of
the disease of which he died, inl was not in a condition to at-
tend to business. Admiral KNowxes was disgusted with the
Admiralty, and with the Ministry, by which he thought him-
selfill-used; so that Mr Rostson had nothing to look for from

personal

OF THE LATE PROFESSOR ROBISON. 505

personal kindness, and could trust only to the justice and mo-
deration of his claims. These were of little advantage to him ;
for such was the inattention of the Lords of the Admiralty,
and the Members of the Board of Longitude, that he could
not obtain access to-any of them, nor even receive from.them
any answer to his memorials.

The pictare which. his letters: to his father present, at this
time, is that of a mind suffering severely from unworthy treat--
ment, where it was least suspected. Men in office do not re-
flect, while they are busy about the concerns of nations, how
mueh evil may be done: by their neglect to do justice to an
individual. They may be extinguishing the fire of genius,
thrusting down merit below the level it should rise to, or prema-
turely surrounding the mind of a young man, witha fence
of suspicion and distrust, worse than the evils which it proposes
toavert. Like other kinds of injustice, this may, however, meet
with its punishment ; though. the victim-of unmerited neglect
may remain for ever obscure, and his: sufferings for ever un-
known, he may also emerge from obscurity, and the treatment
he has met with may meet the eye of the public. It is probable
‘that the member of these- Boards. most conspicuous for rank
or for science, would:not have been above some feeling of re-
gret, if he had learnt that the young man whose petitions he
disregarded, was to become the ornament of his country, and’
the ill treatment he then met with, a material fact.in the his--
tory of his: life...

But though we must condemn the neglect of which. Mr Ro-
g1son had so much reason to complain, we do by no means re-
_gret that the recompense, which he or his friends had in view,
was not actually conferred on him. This was.no other than
an appointment to the place of a purser in-a ship of war3-a
sort of preferment which, to a man of the genius, information,

and

506 BIOGRAPHICAL ACCOUNT

and accomplishment of Mr Rosison, must have turned out ra-
ther as a punishment than a reward. It was, however, the ob-
_ ject which, by the advice of Sir Cuartes Know .es, he now as-
pired to; and, indeed, he had done so, ever after his first voy-
age in the Royal William; for it appears that he had wished
to be made Purser to the Peregrine, at the time when Lieute-
nant Knowles was appointed to the command of that ship,
though, considering its smallness, the situation could have
been attended with little emolument *.

Thus disappointed in his hopes, Mr Rozison resolved on re-
turning te Glasgow, in order to qualify himself for entering
into the Church. Indeed, the idea of prosecuting his original
destination seems often to have occurred to him, even when
his views appeared to have a very different direction. When
he left the Royal William in 1761, he was not without serious
intentions of resuming the study of Theology. This appears,
both from a letter he wrote to his father, about that time, and
from one which he himself received from young Know es,
who rallies him on his new profession, and on the singularity
of having acquired a taste for theological studies in the ward-
room of a man of war. When he undertook the voyage to Ja-
maica, he would have wished to have had the patronage of his

employers, for obtaining some ecclesiastical preferment rather .

than

* It is, however, true, that the place of Purser was afterwards offered to Mr
Rosison, but such a one as he could have no temptation to accept. In 1763,
when Lord Sanpwicu was First Lord of the Admiralty, his solicitations were
so far listened to, that he was appointed to the Aurora, of 40 guns, then
on the stocks. As the ship must be long of being in commission, and the pay of
the Purser, in the mean time, very inconsiderable, Mr Rogison declined accept-
ing this appointment.

=o 9

OF THE LATE PROFESSOR ROBISON. 507

than naval; and only agreed to the latter, as it lay more in
the way of the Board of Longitude to help one to promo-
tion in the Navy than in the’Church. It appears, that he had
never ceased to express to Dr Brain a desire of assuming the
clerical character; and he actually had, from that gentleman,
the offer of a curacy in a living of his own, to which, however,
the emolument annéxed was so small, that, after consultation
with his father, he declined accepting of it.

But however Mr Roptson’s views may have varied, to one
object he steadily adhered, viz. the cultivation of science, and

the acquisition of whatever knowledge the situations he was

placed in brought within his reach.

He returned, therefore, to Glasgow ; and a man whose ob-
ject was the prosecution of science, could not arrive at any
place in a more auspicious moment, as that city was about to:
give birth to two of the greatest improvements, which, in the
eighteenth’ century, have distinguished the progress either of
the sciences or the arts. The one of these was the discovery
of Latent Heat, by the late Dr Brack ; the other, was the in-
vention of what may be properly called a New Steam-engine,
by Mr Warr. The former of these eminent men was then
the Lecturer on Chemistry in the University, and had just
been led, by a train of most ingeniously contrived experi-
ments, to the knowledge of a principle which seemed to pro-
mise better for an explanation of the process which takes place
when heat is communicated to bodies, than any thing yet
known in chemistry, viz. that when water passes from a ‘solid
to a fluid state, as much of its heat disappears, as would have
raised its temperature, had it remained solid, 140 degrees
higher than that which it actually possesses. Mr Ronison
was already known to Dr Brack, having been introduced to

him

508 BIOGRAPHICAL ACCOUNT

him before he left Glasgow; but at that time he had not stu-
died chemistry, to which, however, he was now bending his
attention. He had the advantage of being initiated in it
by the author of the discovery just mentioned, and the new
views struck out by his master, did not fail to interest him
in a study, which, from that time, came to occupy a new place
in physical science. ,

Mechanics had always been his favourite pursuit, and his
turn to whatsoever was connected with it, had brought him to
be acquainted with Mr Warr before 1758, when he left the
University. Mr Wart, who, at that time, exercised the pro-
fession of a mathematical instrument maker, was employed in
fitting up the astronomical instruments bequeathed to the Ob-
servatory by the late Dr Macrarzane of Jamaica. Mr Rost-
son, on his return, found him still residing in Glasgow, and
exercising the same profession, and their former intimacy was
naturally renewed. In 1764, an occurrence such as to an or-
dinary man would have been of no value, gave rise to the im-
provement of the steam-engine. A model of the common en-
gine, NEwcomEn’s, which belonged to the Natural Philosophy
Class, was put into Mr Warv’s hands in order to be repaired.
As the model worked faster than the large engines, it was found
impossible to supply it with steam, and it was in the attempt
to obviate this difficulty, and in trying to produce a more per-
fect vacuum, that the idea of condensing the steam in a sepa-
rate vessel first occurred to him. At the same time, by a cu-
rious. coincidence, his experiments led him to conclusions
concerning the great quantity of heat contained in steam,
that were only to be explained on the principle of Jatent
heat. Mr Roszison lived in a state of great intimacy with
Mr Wart, and was so much acquainted with. the first steps
of this invention, that his evidence on the subject of the

originality

OF THE LATE PROFESSOR ROBISON. 509

‘riginality of it, was afterwards of great use in ascertaining the
justness of his claim.
There could not be a better school for philosophical inven-

tion than Mr Rozison enjoyed at this time, and accordingly,

he used always to say, that it was not till his second re-
sidence at Glasgow that he applied to study with his whole
mind.

Dr Buack was elected Professor of Chemistry in the Uni-
versity of Edinburgh in the summer of 1766; and, on leaving
Glasgow, recommended Mr Rogison as his successor. He
was accordingly made choice of, and began his first course of
chemical lectures in October 1766. He was appointed for one
year only, but his success assured his continuance without any
other limit than such as depended on himself.

He had also the charge of the education of the late Mr Mac-
powaL of Garthland, and of Mr Cuarires Knowres, a son
of the Admiral. But of the particulars, during four years,
about this,time, I have been able to obtain little information.

The friendship of Admiral Knowres had been all along
exerted toward Mr Rosison, with an extraordinary degree of
zeal and assiduity, and was now the means of procuring for
him a very unlooked-for preferment, which removed him from
his academical duties at Glasgow. The Empress of Russia,
convinced of the importance of placing her marine on the
best footing, made an application to the Government of this
country, for permission to engage in her seryice some of the
most able and experienced of our naval officers, to whom -
she might entrust both the contrivance and the execution
of the intended reformation. .The request was agreed to,
and the person recommended was Admiral Sir Cuartres
Know tes, who had long applied, with great diligence, to the

Vou. VII. P. II. 3 T study

510 BIOGRAPHICAL ACCOUNT

study of naval architecture, as well as to that of every branch
of his profession ; and who, about fifty years before, had been
sent to Portugal on a similar mission. A proceeding so free
from that jealousy which often marks the conduct of great.
nations no less than the dealings of the most obscure cor-
porations, is particularly deserving of praise. From the first
moment that this offer was made to the Admiral, he com-
municated it to Mr Roztson, whom he wished to engage as his
Secretary, and to whom, as he says in his letters, he looked
for much assistance in the duty he was about to undertake. A
very handsome appointment was made for Mr Rosrson, and
in the end of December 1770, he set out with Sir Cuarues
and his family on the journey to St Petersburgh, over
land.

Admiral Know es held the office of President of the Board
of Admiralty ; and his intention was, that Mr Rosrson should
have the place of Secretary. The Russian Board, however,
being constituted more on the plan of the French than the
English, there was no place corresponding to that of our Se-
cretary of the Admiralty. Mr Rosison continued, therefore,
in the character of Private Secretary to the Admiral.

During the first year of the Admiral’s residence in Russia,
and for the greater part of the second, Mr Rosison remain-
ed with him, employed in forming and digesting a plan for
improving the methods of building, rigging, and navigating
the Russian ships of war, and for reforming, of consequence,
the whole detail of the operations in. the naval arsenals of that
Empire.

These innovations, however, met with more resistance than
either the Admiral or his Secretary had permitted themselves
to suppose. The work of reform, conducted by a: foreigner,

even

OF THE LATE PROFESSOR ROBISON. Sli

even when he is supported by despotic power, must pro-
ceed but slowly ; jealousy, pride, and self-interest, will conti-
‘nually counteract the plans of improvement, and by their vigi-
Jance and unceasing activity, will never wholly fail of success,
All this was experienced by Admiral Know eEs ; yet there is no
doubt that material advantages were derived, by the Russian
navy, from the new system which he was enabled, partially, to
introduce.

“Mr Rosison, from his first arrival at St Petersburgh, had
applied with great diligence to the study of the Russian
language, and had made himself so much master of it,
as to speak and write it with considerable facility. In
summer 1772, a vacancy happening in the mathematical
chair attached to the Imperial Sea Cadet Corps of Nobles, at
Cronstadt, Mr Roztson was solicited to accept of that. office.
His nautical and mathematical knowledge qualified him singu-
larly for the duties of it, and his proficiency in the Russian
language, removed the only objection that could possibly be
proposed. When he accepted of the appointment, the salary
of his predecessor was doubled, and the rank of Colonel was
given him. Besides delivering his lectures as Professor, he of-
ficiated also as inspector of the above corps, in the room of
General Poririxa, who had retired, or been sent to his estates
in the Ukraine.

The lectures which he gave were very much admired, and
could not fail to be of the greatest use to his pupils. Few
men understood so well the theory and the practice of the arts
they profess to teach; few had enjoyed the same opportunities
of seeing the mathematical rules of artillery and navigation
carried into effect on so great a scale. ‘To his own country-
men, resident at Petersburgh, Mr Rosison was an object of no
less affection than admiration.

3T 2 In

512 BIOGRAPHICAL ACCOUNT:

In 1773, the death of Dr Russetz produced a vacancy: in
the Natural Philosophy Chair of the University of Edinburgh.
Principal Rozertson, who was ever so attentive to the wel-
fare of the University over which he presided, though not per-
sonally acquainted with Mr Rosison, yet knowing his cha-
racter, had no doubt of recommending him to the Patrdns: of
the University, who, on their part, with no less disinterested=
ness, listened to his recommendation, and Mr Rosison was
accordingly elected. It is said, that when the news of this
appointment reached him, he at first hesitated about the ac-
ceptance of it, principally from the fear of appearing in-
sensible to the kindness and favour which he had experi-
enced from the Russian Government. The moment, too,
when it was known that this invitation had been given lim,
further offers of emolument and preferment were made him
by that Government, of such a kind as it was supposed he
could not possibly resist. At length he determined, and
no doubt wisely, however splendid the prospects held out to him
might be, to accept ofa situation that would fix him permanently
in his native country. He therefore declined the offers of the
Empress of Russia, and in June 1774 sailed from. Cronstadt
for Leith, followed, as one of those friends he left behind in
Russia has expressed it, by the regrets, and accompanied by
the warmest good wishes, not only of all who had shared in
his friendship, but of all to whom he was known. The Em-
press was so. far from being offended with his determination,
however much she wished to prevent it, that she settled a pen-
sion on him, accompanied with a request, that he would
receive under his care two or three of the young cadets who
were to be selected in succession.

Mr

OF THE LATE PROFESSOR ROBISON. 518

Mr Rosison was admitted at Edinburgh the 16th Septem-
ber 1774, and gave his first course of lectures in the winter
following. The person to whom he: succeeded had been
very ‘eminent and very useful in his profession. He posses-
sed a great deal of ingenuity, and much knowledge, in
all the branches of Physical Science. Without perhaps being
very deeply versed in the higher parts of the mathematics,
he had much more knowledge of them than is requisite
for explaining the elements of Natural Philosophy. His views
in the latter were sound, often original, and always explained
“with great clearness and simplicity. The mathematical and
experimental parts were so happily combined, that his lec-
tures communicated not only an excellent view of the princi-
ples of the science, but. much practical knowledge concerning |
the means by which. those principles are embodied in matter,
and made-palpable to sense. !

Mr Rostson, who now succeeded to this chair, had also talents
and acquirements of a very high order. The scenes of active
life in which he had been early engaged, and in which he had
seen the great operations of the nautical and the military art,
had been followed, or accompanied, with much study, so that
a thorough knowledge of the principles, as well as the prac- -
tice, of those arts, had been acquired. His knowledge of the -
mathematics was accurate-and extensive, and included, what.
was at that time rare in this country, a considerable familiari-
ty with the discoveries. and inventions of the foreign mathema- .
ticians.

In the generat outline of his course, he did not, however, devi-
ate materially from that which had been sketched by his prede-
cessors, except, I think, in one point of arrangement, by which

he: :

514 BIOGRAPHICAL ACCOUNT

he passed from Dynamics immediately to Physical Astrono-
my. The sciences of Mechanics, Hydrodynamics, Astronomy
and Optics, together with Electricity and Magnetism, were the
subjects which his lectures embraced. These were given with
great fluency and precision of language, and with the introduc-
tion of a good deal of mathematical demonstration. His man-
ner was grave and dignified. His views always ingenious, and
comprehensive, were full of information, and never more inte-
resting and instructive than when they touched on the history of
science. His lectures, however, were often complained of, as
difficult and hard to be followed, and this did not, in my opi-
nion, arise from the depth of the mathematical demonstra-
tions, as was sometimes said, but rather from the rapidity of
his discourse, which was in general beyond the rate at which
accurate reasoning can be easily followed. The singular faci-
lity of his own apprehension, made him judge too favour-
ably of the same power in others. To understand his lec-
tures completely, was, on account of the rapidity, and the uni-
form flow of his discourse, not a very easy task, even for men
tolerably familiar with the subject. On this account, his
lectures were less popular than might have been expected
from such a combination of rare talents as the author of
them possessed. This was assisted by the small number
of experiments he introduced, and a view that he took
of Natural Philosophy which left but a very subordinate
place for them to occupy. An experiment, he would
very truly observe, does not establish a general proposi-
tion, and never can do more than prove a particular fact.
Hence, he inferred, or seemed to infer, that they are of no
great use in establishing the principles of science. This seems
an erroneous view. An experiment does but prove a particu-

lar

|

OF THE LATE PROFESSOR ROBISON. 515

lar fact ; but by doing so in a great number of cases, it affords
the means of discovering the general principle which is
common to all these facts. Even a single experiment may
be sufficient to prove a very general fact. When a guinea
and a feather, let fall from the top of an exhausted receiver, de-
scend to the bottom of it in the same time, it is very true that
this only proves. the fact of the equal acceleration of falling bo-
dies in the case of the two substances just named; but who
doubts that the conclusion extends to all different degrees of
weight, and that the uniform acceleration of falling bodies of
every kind, may safely be inferred.

A society for the cultivation of literature and science had

_ existed in Edinburgh ever since the year 1739, when, by the

advice, and under the direction of Mr Mactavrtn, an associa-
tion, formed some years before for the improvement of Medi-
cine and Surgery, enlarged its plan, and assumed the name of
the Philosophical Society. This Society, which had at differ-.
ent times reckoned among its members some of the first men
of whom this country can boast, had published three volumes
of Memoirs, under the title of Physical and Literary Essays ;
the last in 1756, from which time the Society had languished,
and its meetings had become less frequent. At the time I am
now speaking of, it was beginning to revive, and its tendency
to do so was not diminished by the acquisition of Mr Rosison,,.
who became a member of it soon after his arrival. It had of-
ten occurred, that a more regular form, and an incorporation
by Royal Charter, might give more steadiness and vigour to.
the exertions of this learned body. In 1783, accordingly,.un--
der the auspices of the late excellent Principal of this Univer-
sity, a Royal Charter was obtained, appointing certain persons

; named.

516 _ , BIOGRAPHICAL ACCOUNT

named in it as a New Society, which, as its first act, united to
itself the whole of the Philosophical.

Professor Roxison, one of those named in the original char-
ter, was immediately appointed Secretary, and continued to
discharge the duties of that office, till prevented by the state of
his health several years after.

The first volume of the -Transactions of this paras con-
tains the first paper which Professor Rosison submitted to the
public, a “ Determination of the Orbit and the Motion of the
* Georgium Sidus, directly from Observations,” read in March
1786. This planet had been observed by Dr Herscuexy on
the 13th March 1781, and was the first in the long list of dis-
‘coveries by which that excellent ebserver has for so many
years continued to enrich the science of Astronomy. Its
great distance from the sun, and the slowness of its angu-

Jar motion, which last amounts to little more than four de-
grees from one opposition to the next, made it difficult to de-
termine its orbit with tolerable accuracy, from an arch which
did not yet exceed an eighteenth part of the whole orbit.
This was an inconvenience which time would remedy ; but
impatience to arrive even at such an approximation as the
facts known will afford, is natural in such cases, and Pro-
fessor Rosson, as well as several other mathematicians, were
not afraid to attempt the problem, even in this imperfect state
of the data. It is well known that the observations which best
serve the purpose of determining the orbit of a planet, are
those made at its oppositions to the sun, when an observer in
the Earth and in the Sun would refer the planet to the same
point in the starry heavens, or when, in the language of ‘astro-
nomers, its heliocentric and geocentric pet coincide. Of

these

——

OF THE LATE PROFESSOR ROBISON, 517

these oppositions in the case of this planet, there were yet only
four which had been actually observed. Dr Herscueu had,
however, discovered the planet soon after the opposition of
1781 was passed, and though of course that opposition was
not seen, yet from the observations that were made so soon
after, Professor Rozison thought he could deduce the time with
sufficient accuracy. The opposition of the winter 1786 he
observed himself; for though there was, unfortunately, no ob-
servatory at Edinburgh, he endeavoured to supply that defect
on the present occasion by a very simple apparatus, viz. a tele-
Scope on an equatorial stand, which served to compare the right
ascension and declination of the planet with those of some
known stars which it happened to be near. His general solu-
tion of the problem is very deserving of praise ; and though the
method pursued is in its principle the same with all those which
ever since the time of Kepier have been employed for find-
ing the elements of a planetary orbit, it appears here in a very
simple form, the construction being wholly geometrical, and
easily understood. The elements, as he found them, are not
very different from those that have since been determined
from more numerous and more accurate observations.

When Dr Herscuet first made known this most distant of
the planets, many astronomers believed that they had disco-
vered the source of those disturbances in our system, which
had not yet been explained. Professor Rogison was of this
number ; for he tells us, in the beginning of his paper, that
he had long thought that the irregularities in the motion
of Jupiter and Saturn, which had not been explained by the
mutual gravitation of the known planets, were to be accounted
for by the action of planets of considerable magnitude, beyond
the orbit of Saturn. Subsequent inquiry, however, has not ve-

Vou. VII. P. II. 3U rified

518 BIOGRAPHICAL ACCOUNT

rified this conjecture ; the irregularities of Jupiter and Saturn
have since been fully explained, and are known to arise chiefly
from their action on one another, a very small part only being
owing to that of the pre ade Sidus, or of any of the other
planets.

The next publication of Professor Rosson, was a paper in
the second volume of the same Transactions, “ On the Motion
“ of Light, as affected by Refracting and Reflecting Substan-
“ ces, which are themselves in Motion *.”

The phenomena of the aberration of the fixed stars are , well
known to depend on the velocity of the earth’s motion combi-
ned with the velocity of light ; the quantity of the aberration,
when all other things are given, being directly as the first, and
inversely as the second. It is not, however, the general or the
medium velocity with which light traverses space, but it is the
particular velocity with which it traverses the tube of the tele-
scope, that determines the quantity of this aberration. Were
it possible, therefore, to increase or diminish that velocity, the
aberration would be diminished in the first case, and increased
in the second. But, according to the principles now generally
received in optics, the velocity of light is increased, when it
traverses a denser medium, or one in which the refraction is
greater ; and therefore were the tube of a telescope to be filled
with water instead of air, the aberration would be diminished.
Professor Rosison, and his friend Mr Witson, Professor of
Astronomy at Glasgow, had speculated much on this subject,
and made many attempts to obtain a water telescope, but, hi-
thertc, without effect. A paper of Boscovicu on the same
subject, seemed to suggest some new views, that might render
the experiment more easy to be made. That philosopher

maintained,

* Edinburgh Transactions, vol. ii. p. 83..

OF THE LATE PROFESSOR ROBISON. 519

maintained, that in ascertaining the effect of a water telescope
on the motion of light, the observation of celestial objects might
be dispensed with, and that of terrestrial substituted in its place.
He argued, that while light moves with an uniform velocity,
the telescope must be directed, not to the point of space which
the object occupied when the particle was sent off which is
entering the telescope, but to a point advanced before it by a
space just equal to that which both the object and the obser-
ver have passed over in the time in which the particle has pas-
sed from the object to the eye. It is therefore directed exact-
ly to the place which the object is in when the light from it
enters the eye. If, therefore, the ray, on entering the tele-
scope, is made to move faster than it did before, the telescope
‘must not be inclined so much, and the apparent place of the
object will fall behind its true place. If the ray is retarded on
entering the water, the contrary must happen. Hence a num-
ber of very unexpected phenomena would result, affording,
without having recourse to the heavenly bodies, a direct proof
of the motion of the earth in its orbit, as well as a resolution
of the question, whether light is accelerated or retarded on
passing from a rarer to a denser medium *.

On this reasoning Professor Rozison has very well re-
marked, that it would be just, if the light, on entering the
water telescope, had only its velocity changed, and not its di-
rection. But this is not the case; for the ray that is to go
down the axis of the telescope, is not perpendicular to the
surface of the fluid; it makes an angle with it, depending on
the aberration, and therefore in some cases less by 20” than a
right angle. On this account, the effect is not produced which
Boscovicn’s reasonings lead us to expect.

4U2 . The

* Boscovicu, Opera Math, tom. 11. opusc. 3.

520 BIOGRAPHICAL ACCOUNT

The sequel of the paper is also full of ingenious re-
marks.

In December 1785, Mr Rosison was attacked by a severe
disorder, which, with but few intervals of relaxation, continued
to afflict him to the end of his life, and which, though borne’
with much resignation, and resisted with singular fortitude,
could not but at length impair both the vigour and the conti-
nuity of his exertions. The disorder seemed to be situated be-
tween the urethra and the perineum. At times it was accom-.
panied with the severest pain, and with violent spasms, which
were easily excited. The disease, however, was only known
by the pain produced; and never, by any visible or palpable
symptom, gave information of its nature, as no change in the
parts which were the seat of it could ever be ier yall A
complaint of this nature, it is evident, must have less chance
of being removed than any other, and it accordingly baffled
the art of the most skilful medical men, both in Edinburgh
and London.

Notwithstanding this state of suffering, his general health
was not for a iia time materially injured, nor the powers
of his mind relaxed, so that he continued to prosecute
study with vigour and steadiness. A malady which was both
severe and chronical, admitted of no palliative so good as
the comfort of domestic society, which Mr Rosison happily
enjoyed, having married soon after he settled in Edinburgh.
The care and attention of Mrs Rogison, and the affectionate
regards of his children, as they grew up, were blessings to
which, with all his habits of study and abstraction, he was ever
perfectly alive.

This indisposition did not prevent him from engaging, about
this time, in a very laborious undertaking. A work, with the

* title

OF THE LATE PROFESSOR ROBISON. §21°

title of Encyclopedia Britannica, undertaken at. Edinburgh se-
veral years before this period, was now undergoing a third edi-
tion, in which it was to advance from three to eighteen volumes..
Twelve of these had been already published, under the direc-
tion of the original editor, Mr Cours Macrarquuar, when, on:
his death, the task of continuing the work was committed to:
the care of the Reverend Dr Gueic, and about the same time
Professor Rozsison became a contributor to it. He was the
first contributor who was professedly and really a man of sci-
ence, and from that time the Encyclopedia Britannica ceased
to be a mere compilation. Dictionaries of Arts and Sciences,
in this island, had hitherto been little else than compilations ;
and though in France, the co-operation of some of the most:
profound and enlightened men of the age, had produced a
work of great merit and celebrity, with us compositions of the
same class had been committed to the hands of very inferior
artists. The accession of Professor Ropison was an event of
great importance in the history of the above publication. -

‘It was in the year: 1793 that he began to write in this book,
and it was at the article Opties, with him a very favourite sci--
ence, that his labours commenced. From that time he conti-
nued to enrich the Encyclopedia with a variety of valuable
treatises, till its completion:in 1801.

The general merit of the articles thus composed, makes it
difficult to point out particulars. Those in which theoretical
and practical knowledge are combined, are of distinguished
merit; such are Seamanship, Telescope, Roof, Water-works,
Resistance of Fluids, Running of Rivers. To these I must
add the articles Eleetricity and Magnetism in the Supplement,
where the theories of /p:nus are laid down with great clear-
ness and precision, as well as with very considerable improve-
ments. In ascertaining the law of the electric attraction, his

experiments

522 BIOGRAPHICAL ACCOUNT

experiments were ingenious, as well as original, and afforded
an approximation ‘to the result which the great skill and the
excellent apparatus of Coutoms have since exactly ascertain-
ed. In the Supplement is also containéd a very full account
of the Theory of BoscovicH; a subject with which he was
much delighted, and which he used to explain in his lectures,
with great spirit and elegance.

These articles, if collected, would form a quarto volume of
more than a thousand pages. 1 am persuaded, that when
brought together, and arranged by themselves, they will make
an acceptable present to the public; and I have the satisfac-
tion to state, that such a work is now preparing, under the di-
rection of an Editor whose remarks or corrections cannot but
add greatly to its value. Notwithstanding the merit which the
separate articles possess, they are not entirely free from the
faults incident to whatever is composed for a work already
in the press. The condensation and arrangement, to which
time is such an essential condition, even with men of the
first talents, must be often wanting, in such circumstances ;
and there are, accordingly, in the articles now referred to, a_
diffuseness, and sometimes a want of order, that may easily be
corrected, without injuring the authenticity of the work.

Though the Encyclopedia employed Professor Roztson very
much during the whole of the seven years that it continued, he
nevertheless found leisure for some researches of a very different
nature. At the period of which I now speak, the French Re-
volution had arrested the attention, and excited the astonish-
ment of all Europe; and the satisfaction with which the first
efforts of a nation to assert its liberties, had been hailed from
all quarters, was, by the crimes and excesses which followed,
quickly converted into grief and indignation. A body was
put in motion sufficient to crush whole nations under its

weight ;

OF THE LATE PROFESSOR ROBISON. 523.

weight ; none had the power or the skill to direct its course 5.
what movements it might communicate to other bodies, how
far it would go, or in what quarter, it seemed impossible to
foretel. The amazement. became general; no man was so
abstracted from the pursuits of the world, or so insula
ted by peculiarities of habit and situation, as not to feel
the effects of this powerful concussion. All fixed their eyes
on the extraordinary spectacle which France exhibited ; where,
if time is to be measured by the succession of events, a year
was magnified into an age; and when in a few months one
might behold more old institutions destroyed, and more new
ones projected or begun, than in all the ten centuries which
had elapsed between CuarLEMacneE and the last of his succes-
sors:—lIn a word, where the ancient edifice, founded in the
ages of barbarism with such apparent solidity, strengthened
and adorned in the progress of civilisation with so much skill
and labour, was in one moment levelled with the dust. A ge-
neral state of alarm and distrust was the effect of the convul-.
sions which men saw every where around them ; where the in-
stitutions held as sacred from their origin, or venerable from
their antiquity, and essential to the order of society, were seen,
not falling to pieces from natural decay, but blown up by the
force of a sudden and unforeseen explosion. From such a
condition of the world, jealousy and credulity could not fail to
arise. When danger is all around, every thing is of course
suspected ; and when the ordinary connection between causes.
and effects cannot be traced, men have no means of distinguish-
ing between the probable and the improbable ; so that their
opinions are dictated by their prejudices, their impressions, and
their fears. Such, accordingly, was the state into which mens.
minds were brought at this extraordinary crisis; and even in
this country, removed, as we were, from the danger, by so

strong

524 BIOGRAPHICAL ACCOUNT

trong a barrier of causes, both moral and physical, the alarm
‘was general and indiscriminate. The progress of knowledge
was supposed by many to be the cause of the disorder; pane-
gyrics on ignorance and prejudice were openly pronounced ;
the serious and the gay joined in declaiming against reason
and philosophy ; and all seemed to forget, that when reason
and philosophy have erred, it is by themselv es alone that their
errors can be corrected.

The fears that had thus taken possession of mens’ minds,

were often artificially increased. It was supposed that the ge- -

neral safety depended on the general alarm ; that the more the
terror was extended, the more would the object of it be resist-
ed ; and hence, doubtless, many felt it their interest, and some
considered it their duty, to magnify the danger to which the
public was exposed.

It is evident, that an inquiry into the causes of the French
Revolution, undertaken at a moment of such agitation, was
not likely to bear the review of times of calm and sober reflec-
tion. It was at this moment, however, and under the influ-
ence of such impressions, that Mr Rozison undertook to ex-
plain the causes of that revolution. He was deeply affected
by the scenes that were passing before him. He possessed great
sensibility, and his mind, peculiarly alive to immediate im-

pressions, felt strongly the danger to which the social order of _

every nation seemed now to be exposed. _ The crimes which
the name of Liberty had been employed to sanction, filled him
with indignation, and the contempt of religion, affected by
many of the leaders of the Revolution, wounded those senti-
ments of piety which he had uniformly cherished from his

early youth.
In such circumstances, a mind accustomed to inquire inte
causes, as his had long been, could not abstain from the at-
tempt

—

OF THE LATE PROFESSOR ROBISON. 525

‘tempt to trace the sources of so extraordinary a succession of
events. As to the circumstances which first led him, and led
him, I think,.so unhappily, to look for those sources in the
institutions of Free Masonry, or in the combination of some
German mystics, I have nothing satisfactory to offer. He was
accustomed to refined and subtle speculations, and naturally
entertained a partiality for theories that called into action the
powers by which he was peculiarly distinguished.

In 1797, he published a book, entitled, “ Proofs of a Con-
“ spiracy against all the Religions and Governments of Eu-
“ rope.” He supposes, that this conspiracy originated in the
Lodges of the Free Masons, but that it first assumed a regu-
Jar form in the hands of certain philosophic fanatics, distin-
guished in Germany by the name of J//uminati ; that after the
suppression of this society by the authority of Government,
the spirit was kept alive by what was called the German
Union ; that its principles gradually infected most of the phi-
losophers of France and Germany, and lastly broke forth with
full force in the French Revolution.

The history of J//uminatism, as it is called, forms the princi-
pal part of the work ; and on a subject involved in great my-
stery, where all the evidence came through the hands of friends
or of enemies, it was exceedingly difficult for one living in a
foreign country, and a stranger to the public opinion, to obtain
accurate information. Accordingly, the events related, and
the characters described, as proofs of the conspiracy, are of so
extraordinary a nature, that it is difficult to persuade one’s
self that the original documents from which Mr Rosison
drew up his narrative were entitled to all the confidence which
he reposed in them. |

I do not mean to question the general fact, that there did
exist in Germany a society having the vanity to assume the

Vor: WIL. P. IL 3X name

526 BIOGRAPHICAL ACCOUNT

name just mentioned, and the presumption or the simplicity
to believe that it could reform the world: In a land where

the tendency to the romantic and the mysterious seems so ge-

neral, that even philosophy and science have not escaped the
infection, and in states where there is much that requires
amendment, it is not wonderful if associations have been form-
ed for redressing grievances, and reforming both religion and
government. Some men, truly philanthropic, and others,
merely profligate, may have joined in this combination ; the

former, very erroneously supposing, that the interests of truth

and of mankind may be advanced by cabal and intrigue ; and
the latter, more wisely concluding, that these are engines well
adapted to promote the dissemination of error, and the
schemes of private aggrandisement. An ex-Jesuit may have
been the author of this plan, and whether he belonged to the
former or the latter class, may have chosen for the model of
the new arrangement, those institutions which he knew from
experience to be well adapted for exercising a strong but secret
influence in the direction of human affairs.

In all this there is nothing incredible; but the same, I
think, cannot be asserted, when the particulars are examined
in detail. It is extremely difficult, as has already been re-
marked, for a foreigner, in such circumstances as Mr Rost-
son’s, to avoid delusion, or to determine between the different
kinds of testimony of which he must make use. ‘With me,
who have no access to the original documents, and if I had,
who have neither leisure nor inclination to examine them, an
opinion can only be formed from the internal evidence, that is,
from the nature of the facts, and the style in which they
are recorded. The style of the works from which Mr Rosr-
son composed his narrative, is not such as to inspire confi-
dence ; for, wherever it is quoted, it is that of an angry and in-

flated

OF THE LATE PROFESSOR ROBISON. 527

fated invective. The facts themselves are altogether singular,
arguing a depravity quite unexampled in all the votaries of
illumination. From the perusal of the whole, it is impossible
not to conclude, that the alarm excited by the French Revolu-
tion, had produced in Mr Rosison a degree of credulity which
was not natural to him. The suspicion with which he seems to
view every person on the continent, to whom the name of a Phi-
losopher can be applied, and the terms of reproach and con-
tempt to which, whether as individuals or as bodies, they are
always subjected, make it evident that the narrative is not im-
partial, and that the author was prepared, in certain cases, to
admit the slightest presumption as clear and irrefragable evi-
dence. When, indeed, he speaks of such obscure men as com-
posed the greater part of the supposed conspirators, we have
no direct means of determining in what degree he has been
misled. But when we see the same sort of suspicion and
abuse directed against the best known and most justly celebra-
ted characters of the age, we cannot but lament the prejudices
_ which had taken possession of an understanding in other mat-
ters so acute and penetrating.

Among the men engaged in public affairs, of whom Europe
boasted during the last century, there was perhaps none of a
higher character than Turcot, who, to the abilities of a states-
man, added the views of a philosopher; was a man singularly
patriotic and disinterested, distinguished by the virtues both of
public and private life, and having, indeed, no fault but that
of being too good for the times in which he lived. Yet Mr
Rosison has charged this upright and humane minister with
an exercise of power, which would argue the most extreme
depravity. He states*, that there existed in Paris a com-

3X 2 bination

* Proofs-of a Conspiracy, &c. 4th Edit. Note, p. 584.

528 BIOGRAPHICAL ACCOUNT

bination under the direction of the Wits and Philosophers,
who used to meet at the house of Baron D’Horsacn, having
for its object the dissection of the brains of living children,
purchased from poor parents, in order to discover the prin-
ciple of vitality. The police, he adds, interposed to put a
stop to these bloody experiments, but the authors of them
were protected by the credit of Turcor.

All this is asserted on the authority, it should seem, of some
anonymous German publication. I will not enter on the re-
futation of a calumny with the fabrication of which Mr Rosr-
’ son is not chargeable, though culpable without doubt, for ha-
ving allowed his writings to become the vehicle of it. Truth
and justice require this acknowledgment ; and, in making it, I
think that I am discharging a duty both to Mr Rosrson and
myself :—It is a duty to Mr Rostson, in as much as a conces-
sion made by a friend, is better than one extorted by an ad-
versary ; it is a duty to myself, because I should feel that I was
doing wrong, were I even by silence to acquiesce in a repre-
sentation which I believed to be so ill-founded and unjust.

The Proofs of the Conspiracy, notwithstanding these imper-
fections, or perhaps on account of them, were extremely po-
pular, and carried the name of the author into places where
his high attainments in science had never gained admission for
it. In the course of two years, the book underwent no less
than four editions. It is a strong proof of the effect on the
minds of men produced by the French Revolution; and of
the degree in which it engrossed their thoughts, that the his-
tory of a few obscure enthusiasts in Bavaria or Wirtemberg,
when it became associated with that Revolution, was read in
Britain with so much avidity and attention.

The

OF THE LATE PROFESSOR ROBISON. 529

The defects of the evidence were concealed by the prejudi-
ces and apprehensions which were then so general. The peo-
ple of this country were disposed to believe every thing unfa-
vourable to the French nation, but particularly to the philoso-
phers. All might not be equally culpable, but to discriminate
between them was not thought of much importance, and it was
the simplest, if not the fairest way, to divide the demerit equal-
ly among the whole. The rhapsodies of Barauet had already
prepared the public for such impartial decisions, and had held
up every man of genius and talents, from Monresqureu to:
Conporcet, as objects of hatred and execration.

But whatever opinion. be formed of the facts related in the
history of this conspiracy, it is certainly not in the visions of
the German []luminati, nor in the ceremonials of Free Mason-
ry, that we are to seek for the causes of a Revolution, which
has shaken the civilised world from its foundations, and left
behind it so many marks, which ages will be required to ef-
face. There is a certain proportionality between causes and
their effects, which we must expect to meet with in the moral
no less than in the natural world ; in the operations of men as
well as in the motions of inanimate bodies. Whenever a.
great mass of mankind is brought to act together, it must be
‘In consequence of an impulse communicated to the whole, not
in consequence of a force that can act only on a few. A.
Hermit or a Saint might have preached a crusade to the
Holy Land, with all the eloquence which enthusiasm could
inspire; but if a spirit of fanaticism and of chivalry. had not
pervaded every individual in that age, they would never have
led out the armies of Europe to combat before the walls of Je-
rusalem. Neither could the influence of a small. number
of religious or philosophic fanatics, sensibly accelerate or
retard those powerful causes which prepared from afar the

| destruction

530 BIOGRAPHICAL ACCOUNT

destruction of the Freach monarchy. When opposed to these
causes, such influence was annihilated ; when co-operating with
them, its effects were imperceptible. It was a force which
could only follow those already in action; it was like “ dash-
“* ing with the oar to hasten the cataract,” or, “ waving with
“a fh to give swiftness to the wind *.”

It is, however, much easier to say what were not, than what
were, the causes of the French Revolution; and in dissenting
from Professor Rontsen, I will only remark in general, that I
believe the principal causes te be involved in this maxim, That
a certain relation between the degree of Knowledge diffused
thr ough a nation, and the degree of Political Liberty enjoyed
by it, is necessary to the stability of its government. The
knowledge and information of the French people, exceeded
the measure that is-consistent with the entire want of political
liberty. The first great exigency of Government, therefore,
the first moment of a weak administration, could hardly fail to
produce an attempt to obtain possession of those rights, which,
though never enjoyed, can never be alienated. Such an occa-
sion actually occurred, and ‘the revolution which took place
was entire and terrible. This also was to be expected; for
there seems to be among political institutions, as among me-
chanical contrivances, two kinds of equilibrium, which, though
they appear very much alike in times of quiet, yet, in the mo-
ment of agitation and difficulty, are discovered to be very dif-
ferent from one another. - The one is tottering and inse-
cure, in so much that the smallest departure from the ex-
act balance leads to its total subversion. The other is stable,
so that even a violent concussion only excites some vibrations
backward and forward, after which every thing settles in its

Own

* Frrauson’s Essay on Civil Soctety, Part ur. Sect. 4.

OF THE LATE PROFESSOR ROBISON. 53E

own place. Those governments in which there is no political:
liberty, and where the people have no influence, are all una-
voidably in the first of these predicaments: those in which:
there is a broad basis of liberty, naturally belong to that in:
which the balance re-establishes itself. The same weight, that
of the people, which in the first case tends to overset the ba-
lance, tends in the second to restore it: and hence, probably,.
the great difference between the result of the French Revolu-
tion, and of the revolutions which formerly took. place in this-
country.

It will be happy for mankind, if they learn from these disas--
ters, the great lessons which they seem so much. calculated to:
enforce, and if while the people reflect on the danger of sud-
den innovation, their rulers consider, that it is only by a gra-
dual reformation. of abuses, and by extending, rather than:
abridging, the liberties of the people, that a. remedy can be:
provided against similar convulsions.

But I return willingly from this digression, to those branches
of knowledge, where, in describing what Mr Rosison has
done, the language of truth and of praise will never be found
at variance with one another.

In autumn 1799, this country had the misfortune to lose:
one of its brightest ornaments, Dr Biacx, who had laid the:
foundation of the Pneumatic Chemistry, and discovered the
principle of Latent Heat. The Doctor had published very
little; and his discoveries were more ntmerous than his writ-
ings. His lectures, however, had drawn much attention ; they
presented the first philosophical views of chemical science;.
they were remarkable for their perspicuity and clegance, and
this, joined to the simplicity and gracefulness of manner in
which they were delivered, made them universally admired.

It

532 BIOGRAPHICAL ACCOUNT

It was now proposed to publish these lectures ; but this requi-
red that they should be put into the hands of some one able to
perform the part of an editor, and to prepare for the press the
notes from which the Doctor used to read his lectures. The
person naturally thought of was Mr Rostson, one of Dr
Brack’s oldest friends, and so well skilled in chemistry, that
no one could be supposed to execute the work with more zeal
or more intelligence. The task, however, was by no means
easy. Dr Bracx, with a very large share of talent and genius,
with the most correct taste and soundest judgment, with no
habits that could dissipate his mind, or withdraw it from the
pursuits of science, was less ardent in research, and less stimu-
lated by the love of fame, than might have been expected from
such high endowments. A state of health always delicate, and
subject to be deranged by slight accidents, was probably the
cause of this indifference. Hence the small number of his
writings, and his sudden stop in that career of discovery on
which he had entered with such brilliancy and success. Of
much that he had done, the world had never heard any thing,
but from verbal communication to his pupils, and on the sub-
ject of latent heat, no written document remained to ascertain
to him the property of that great discovery. The only means of
repairing this loss, and counteracting the injustice of the world,
was the publication which Professor Rozgrson now undertook
with so much zeal, and executed with so much ability. Dr
Brack had used to read his lectures from notes, and these of-
ten but very imperfect, and ranged in order by marks or
signs only known to himself. The task of editing them was
therefore difficult, and required a great deal both of time and
labour, but was at last accomplished in a manner to give great
satisfaction. The truth, however, is, that the time was past
when this work would have met in the world with the recep-

tion

OF THE LATE PROFESSOR ROBISON. 533

tion which it deserved. Chemical theories had of late under-
gone great changes, and the language of the science was entirely
altered. Dr Brack, on the subject of these changes, had corre-
sponded with Lavoisier, and the mutual respect of two great
men for one another, was strongly marked in the letters which
passed between them. The Doctor had acceded to the chan-
ges proposed by the French chemist, and had even adopted
the new nomenclature; but his notes had not undergone the
alterations which were necessary to introduce it throughout.
It would now have been difficult to make those alterations;
and Mr Rostson, who was not favourable to the new chemistry,
did not conceive that by making them, he was permanently —
serving the interest of his friend. He conceived, indeed, that
there was unfairness in the means employed by Lavoisier, for
bringing Dr Brack to adopt the new system of chemistry, and
has thrown out some severe reflections on the conduct of the
former, which appear to me to rest on a very slight founda-
tion.

It was quite natural for a man, convinced, like Lavoisier, of .
the importance of the improvements which he had made in
chemistry, to be desirous that they should be received by the
- most celebrated Professor of that time,—by the very man, too,
whose discoveries had opened the way to those improvements.
His letters to Dr Brack, contain expressions of respect and
esteem, which, I confess, appear to me perfectly natural, and
without any thing like exaggeration or deceit. Indeed it is
not probable that M. Lavoisier, even if he could himself
have submitted to flatter or cajole, could conceive that any
good effect was to arise from doing so, or that there was any
other way of inducing a grave, cautious, and profound phi-

Vou. VII. P. I. 3 Y ’ losopher,

534 - BIOGRAPHICAL ACCOUNT

losopher, to adopt a certain system of opinions, but by con
vincing him of their truth? He had, with those who knew
him, the character of a sincere man, very remote from any
thing like art or affectation. We must therefore ascribe the
view which Mr Rosison took of this matter, to the same
system of prejudices on which we have had already occa-
sion to animadvert. Such, indeed, was the force of those
prejudices, that he considered the Chemical Nomenclature,,
the new System of Measures, and the new Kalendar, as all
three equally the contrivances of men, not so much interest-
ed for science, as for the superiority of their own nation. Now,,.
whatever be said of the Kalendar, the. project of uniform.
Weights and Measures is admitted to be an admirably contri-
ved system, which Britain is now following at a great distance ;.
and the New Nomenclature of Chemistry to be a real scienti-
fic improvement, adopted all over Europe.. Many of the radi-.
cal words.may depend on false theories, and may of course re-
quire to be changed ; but though the matter pass away, the
form will remain ; the words.of the language may perish, but.
the mould in which the language was cast will never be de-.
stroyed *. The Lectures appeared in 1803..

The

* The high opinion which Mr Rosrson elsewhere expresses of Lavoisier, is
very remarkable. In his Astronomy, published a year after the Lectures, in
stating Hoox’s anticipation of the Principles of Gravitation, he concludes
thus: “It is worthy of remark, that in this clear and candid and modest.
“¢ exposition of a rational theory, Hoox anticipated the discoveries of NewrTon,.
as he anticipated with equal distinctness and precision, the discoveries of Lavor-
ster, a Philosopher inferior perhaps only to Newton.” (Elements of Mechané:.
cal. Philosophy, p. 285.)-

OF THE LATE PROFESSOR ROBISON. 535

The last of Mr Rozstson’s works was one which he had long
projected, though he now set about the completion and ar-
rangement of it, for the first time. It was entitled, Elements of
Mechanical Philosophy, being the substance of a course of le@_
tures on that science. ‘“ Mechanical Philosophy” was, with
him, a favourite expression ; it was understood as. synony-
mous with Natural Philosophy, and included the same
branches. The first volume, the only one he lived to finish,
included Dynamics and Astronomy, and was published in
1804. It isa work of great merit, and is accessible to those
who have no more than an elementary knowledge of the ma-
thematics. The short view of the phenomena prefixed to the
Physical Astronomy is executed in a masterly manner. The
same may be said, and perhaps even with more truth, of the
Physical Astronomy itself; for there are very-few of the ele-
mentary treatises on that branch of science which can be com-
pared with it, either for the facility of the demonstration, or
the comprehensiveness of the plan. The first part is meant to
be popular and historical, and is so at the same time that it is
philosophical and precise. The work is indeed highly esti-
mable, and is entitled to much more success in the world than
it has actually had.

We have already taken notice of Mr Rosrson’s illness, with
which he had been now afflicted for the long period of nine-
teen years. His sufferings, though not equal, had been often
extremely severe. They had occasionally rendered him unable
to discharge his duty in the College, and of late his friend, the
Reverend Dr Tuomas Mackntent, had, with great kindness and
ability, frequently supplied his place. Against such a conti-
nuance of ill health, with so little hopes of recovery as could
be entertained for a long time past, hardly any mind could be

expected

536... BIOGRAPHICAL ACCOUNT

expected to remain in full possession of activity and vigour.
This is the more difficult, as the valuable medicine which alone
in such cases can assuage pain, contributes itself at length to
weaken the mind, and to destroy its energy. The combat
which Mr Rosison had maintained against these complica-
ted evils, had indeed been wonderfully vigorous and successful,
and the last of his works is quite worthy of his days of most
perfect health and enjoyment.

The body could not resist so well as the mind. In the end
of January 1805, he was suddenly seized with a severe illness,
which put an end to his life in the course of forty-eight hours.
There was a general disturbance of the system, which, without
having the character of any defined disease, exhibited those
symptoms of universal disorder which denote a breaking up of
the constitution, and never fail to terminate fatally.

On reviewing the whole of his character, and the circum-
stances of his life, it is impossible not to see in him a man of
extraordinary powers, who had enjoyed great opportunities for
improvement, and had never failed to turn them to the best
account. He possessed many accomplishments rarely to be
met with in a scholar, or a man of science. He had great skill
and taste in music, and was a performer on several instru-
ments. He was an excellent draughtsman, and could make .-
his pencil a valuable instrument either of record or invention.
When a young man, he was gay, convivial, and facetious, and
his vers de soci¢té flowed, I have been told, easily and with
great effect. His appearance and manner were in a high de-
gree favourable and imposing; his figure handsome, and his
face expressive of talent, thought, gentleness, and good temper.

When

OF THE LATE PROFESSOR ROBISON. 537%

When I had first the pleasure to become acquainted with him,
the youthful turn of his countenance and manners was begin-
ning to give place to the grave and serious cast, which he ear-
ly assumed; and certainly I have never met with any one
whose appearance and conversation were more impressive than
his were at that period.

Indeed his powers of conversation were very extraordinary,
and when exerted, never failed of producing a great effect.
An extensive and accurate information of particular facts, and
a facility of combining them into general and original views,
were united in a degree of which I am persuaded there have
been few examples. Accordingly, he would go over the most
difficult subjects, and bring out the most profound remarks, with
an ease and readiness which was quite singular. The depth of
his observations seemed to cost him nothing ; and when he said
any thing particularly striking, you never could discover any ap-
pearance of the self-satisfaction so common on such occasions.
He was disposed to pass quite readily from one subject to ano-
ther ; the transition was a matter of course, and he had per-
fectly, and apparently without seeking after it, that light and
easy turn of conversation, even on scientific and profound sub-
jects, in which we of this island are charged by our neigh-
bours with being so extremely deficient.

The same facility, and the same general tone, was to be seen
in his lectures and his writings. He composed with sin-
gular facility and correctness, but was sometimes, when he
had leisure to be so, very fastidious about his own compo-
sitions.

In the intercourse of life, he was benevolent, disinterested,,
and friendly, and of sincere and unaffected piety. In his in-

terpretation

538 BIOGRAPHICAL ACCOUNT

terpretation of the conduct of others, he was fair and liberal,
while his mind retained its natural tone, and had not yield-
ed to the alarms of the French Revolution, and to the bias
which it produced.

His range in science was most extensive; he was familiar
with the whole circle of the accurate sciences, and there was
no part of them on which, if you heard him speak or lecture,
you would not have pronounced it tobe his fort, or a subject
which he had studied with more than ordinary attention. In-
deed, the rapidity with which his understanding went to work,
and the extent of ground he seemed to have got over, while
others were only preparing to enter on it, were the great fea-
tures of his intellectual character. In these he has rarely been
exceeded. With such an assemblage of talents, with a mind
so happily formed for science, one might have expected to
find in his writings more of original investigation, more works
of discovery and invention. I must remark, however, that
from the turn his speculations and compositions took, or ra-
ther received from circumstances, we are apt to overlook
what is new and original in a great part of them. An
article in a Dictionary of Science must contain a System,
and what is new becomes of course so mixed up with the
old and the known, that it is not easily distinguished. Many
of Mr Rostson’s articles in the Encyclopedia Britannica are
full of new and original views, which will only strike those
who study them particularly, and have studied them in other
books. In Seamanship, for example, there are many such re-
marks ; the fruit of that knowledge of principle which he com-
bined with so much experience and observation. Carpentry,
Roof, and many more, afford examples of the same kind.
The publication now under the management of Dr Brews-

TER,

OF THE LATE PROFESSOR ROBISON. 539

sTER, will place his scientific character higher than it has ever
been with any but those who were personally acquainted
with him. With them, nothing can add to the esteem which:
they felt for his talents and worth, or to the respect in which:
they now hold his memory..

END OF THE SEVENTH VOLUME-,.

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APPENDIX,

Containing Lists of the Orrice-Bearers and Mempers elected
: since November 1812.

23d November 1812.
OFFICE-BEARERS.

Sir James Hatt, Baronet, President.

Lord Wess SrymMour : :
; > + Vice-Presidents.
Lord MrapowsBank,
Professor Piayrair, Secretary.
James Bonar, Esq. Treasurer.
Tuomas ALLaNn, Esq. Keeper of the Museum.

PHYSICAL CLASS. |
Sir Grorce Mackenzie, Baronet, President.
Tomas Cuares Hope, M. D. Secretary.

Counsellors.
: James Grecory, M. D.
Lord Hermann.
Dueaxp Stewart, Esq.
Vou. VII. P. II. 3Z ALEXANDER

542 ; APPENDIX.

_ Atexanper Keiru, Esq.
James Russeix, Esq. Surgeon..
Danret Ruruerrorp, M. D.

LITERARY CLASS,

Henry Mackenzie, Esq. President.
Tuomas Tuomson, Esq. Secretary. | 3)

Counsellors.
Davin Hume, Esq.
Reverend Principal Barrp.
The Lorp PresipEnt.
Lord Rosertson.
Reverend Sir Henry Moncrerrr Weiiwoop, Baronet-.
Reverend Arcuipatp ALIson.. |

25th January 1813..

MEMBERS’ ELECTED.
_ HONORARY.

M. Ix Comte 1a Prace, Member of the Institute, and of the
Board of Longitude of France, &c.

M. Le Comre Lacrancr, Member of the Institute and Board
of Longitude of France, &c:

M. G. Cuvier, Member of the Institute of France, : =

of Anatomy, &c.
ORDINARY. .

APPENDIX. 543

ORDINARY.

Reverend. ALexanpER Murray, Professor of Hebrew and
Oriental Languages in the University of Edinburgh.
Witi1am Sommervitte, M.D. Deputy Inspector of Military

Hospitals in Scotland.
James Hare, M. D. late of Calcutta.
ALEXANDER Boswe.L, Esq. of Auchinleck.
Henry Davinson, M, D. Physician in Edinburgh.

22d November 1818.
OFFICE-BEARERS.

Sir James Hatt, Baronet, President.

‘Lord Mreapowsank, | i : ;
Vice-Presidents.
Lord Wess Seymour,

-Professor Piayrarr, Secretary.
James Bonar, Esq. Treasurer.
‘Tuomas ALLAN, Esq. Keeper of the Museum.

PHYSICAL CLASS.

_ Sir Grorce Mackenzie, Baronet, President.
Tuomas Cuartes Hopes, M. D. Secretary.

~ Counsellors.

Professor DucaLtp Stewart,
ALEXANDER Keir, Esq.
James Russe.y, Esq. Surgeon.
Daniet Rutuerrorp, M. D.
James Bryce, Esq. Surgeon.
Davin Brewster, LL. D.

3Z 2 LITERARY

544

APPENDIX,

LITERARY CLASS.
Henry Macxenzix, Esq. President.
Tuomas Tuomson, Esq. Secretary.

Counsellors.

The Lorp PresipEnt.
Lord Rozertson.

_ Reverend Sir Henry Moncreirr Waser Bart.

Reverend Arcuipatp ALISON.
Watter Scort, Esq.
‘Reverend Dr Jamieson.

-

24th January 1814.

MEMBERS ELECTED.
HONORARY.

M. L’asse’ Havy, Professor of Mineralogy in the Museum

of Natural History, and Member of the National Insti-
tute of Paris.

ORDINARY.
Henry Jarpine, Esq. W. S.
Mr Patrick Nett.
Lord Viscount ArpuTHNoTT.
Reverend Joun Tuomson, Duddingston.
Reverend Joun Friemine, Flisk.
Dr Joun Cueyne, Dublin.
Hay Donatpson, Esq. W. S.
Sir James Macrnrosu, Baronet, M. P.
Colonel Tyrier, Assistant Quarter-Master General:
for Scotland.
Reverend ALexanper Brunton, D. D. Edinburgh.
Professor Grorce GLEeNnniz, Marischall College, Aber
deen,
28th

APPENDIX. 545.

28th November 1814.
OFFICE-BEARERS.

Sir James Hatt, Baronet, President.

Lord Mrapowsank,

Vice-Presidents.
Lord Wess oo Sk ehabe

Professor PLayrair, Secretary.
James Bonar, Esq. Treasurer.

Tuomas ALLAN, Esq. Keeper of the Museum.

PHYSICAL CLASS.

Sir Grorce Mackenzie, Baronet, President.

Tuomas Cuartes Horr, M. D. Secretary.

Counsellors.

JamES Russewx, Esq.

Dr RutTuHerrorp.

James Bryce, Esq.
Davin Brewster, LL. D.
Sir W. Forszs, Baronet.
Dr Anprew Coventry,

LITERARY

b46 APPENDIX. |

LITERARY CLASS.

Henry Macxenzrr, Esq. President.
Tuomas Tuomson, Esq. Secretary.

Counsellors.

Reverend Sir Henry Moncretirr Wexiwoop, Baronet.
Reverend ArcuHiBaALD ALISON.
Watrter Scorr, Esq.

Reverend Dr Jamieson.

Lord GLeNLEE.

Dr Tuomas Brown.

19th January 1815.

MEMBERS ELECTED.
HONORARY.

Baron ALEXANDER DE Humsoitpt, Member of the Institute of

France.

M. Araco, Member of the Institute of France, Astronomer
Royal, and Professor of the Polytechnic School.

M. Gay Lussac, Member of the Institute of France, and Pro-
fessor of the College of France.

M. Brot, Member of the Institute of France, of the Board of
Longitude, and Professor of Natural History i in the Col-
lege of France.

ORDINARY

APPENDIX: 547

ORDINARY.

Gitsert Laine Meason, Esq. of Lindertis..

Rosert Stevenson, Esq. Civil Engineer.

Tuomas Lauper Dick, Esq. younger of Fountainhall.

Joun Yue, M. D. Physician in Edinburgh.

Hrnry Home Drummonp, Esq. younger of Blair Drum-
mond. |

Wiuitam Cuartes We tts, M.D. Physician in London, and
Le

Cuartes GranvitteE Stewart MeEnreatn, Esq. of.
Closeburn.

Wiitam Tuomas Branope, Esq. F.R.S. and Professor of
Chemistry in the Royal Institution of London.

END OF VOL. VII>.

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