TRANSACTIONS

OF THE

ROYAL SOCIETY OF EDINBURGH.

Vou. IX.

: EDINBURGH:
PRINTED FOR WILLIAM & CHARLES TAIT, PRINCE’S STREET,

AND LONGMAN, HURST, REES, ORME, & BROWN,
LONDON.

1823.

VI.

., CONTENTS

OF

VOLUME NINTH.

PART FIRST.

On the Parallel Roads of Lochaber. By Thomas
Lauder Dick, Esq. F. R. S. Edin. -

. On the Poisonous Fishes of the Caribbee Islands.

By William Ferguson, M. D. F. R. S. Edin.

. Account of a Mineral from Orkney. By Thomas

Stewart Traill, M. D. F. R. S. Edin. =

. Extract from Inspection-Report of the Island of Tri-

nidad, made in the Year 1816, by the Inspector
of Hospitals, in conjunction with the Quarter-
Master General and Chief Engineer for the Wind-
ward and Leeward Colonies of the West Indies.
By William Ferguson, M. D. F. R. S. Edin.
Memoir on the Repeating Reflecting Circle. By Ma-
jor-General Sir Thomas Brisbane, C. B. F. R. S.
Edin. and Corresponding Member of the Aca-
demy of Sciences, - -
Description of a Fossil Tree found in a Quarry at
Nites-hill, the Property of Colonel Dunlop of
Househill. By the Reverend Patrick Brewster,
one of the Ministers of the Abbey Church, Paisley,
VIL

Page

81

93

Sa

103

VII.

CONTENTS.

Account of a non-descript Worm (the Ascaris
pellucidus) found in the Eyes of Horses in
India. In Letters from Alexander Kennedy,
M. D. F. R. 8. Edin. to Professor Russel and
Dr Hope. With a Description of the Animal,
by Captain Thomas Brown, F. R. S. Edin.
&¥ Eos: -

VIII. Memoir relating to the Naval Tactics of the late

IX.

2.

XI.

Joun Crerx, Esq. of Eldin; being a Frag-
ment of an intended Account of his Life. By
John Playfair, F. R. S. Lond. & Edin.

On Circular Polarisation, as exhibited in the Op-
tical Structure of the Amethyst, with Remarks
on the Distribution of the Colouring matter in
that Mineral. By David Brewster, LL. D.
F. B.S, Lond. & Edin. - -

An Examination of some Questions connected with

Games of Chance. By Charles Babbage, Esq.

F. R. S. Lond. & Edin. - -
On the Radiation of Caloric. By the Reverend
Thomas Crompton Holland, =

XIL. Notice respecting a Remarkable Shower of Hail

which fell in Orkney on the 24th of Fuly 1818.
By Patrick Neill, F. R.S.E., F,L.S. & Sec.
Wern. Soc. - -

XILL. Observations on the Mean Temperature of the

Globe. By David Brewster, LL. D. F. RB, S.
Lond. & Sec. R. 8. Edin.

XIV. Method of determining the Latitude, es a Sex-

tant or Circle, with simplicity and accuracy,
from Circum-meridian Observations, taken near
Noon. By Major-General Sir Thomas Bris-
bane, C. B. F.R.S. Edin. and Correspond-
ing Member of the Academy of Sciences,

XV.

Page

107

113

139

153

179

187

201

227

CONTENTS.

XV. Description of a Vegetable Impression found in
the Quarry of Craigleith. By Thomas Al-

. lan, Esq. F. B.S. Lond. & Edin. -
XVI. Account of the Native Hydrate of Magnesia,
discovered by Dr Hibbert in Shetland. By
David Brewster, LL.D. F.R.S: Lond. &

. Sec. R. S. Edin. - - -
XVII. Description of a Magnetimeter, being a New
Instrument for Measuring Magnetic Attrac-
tions, and finding the Dip of the Needle ;
with an Account of Experiments made with
it. By William Scoresby, Esq. jun. F. R. S.

Edin. M. W. S. &c. - -

XVIII. Account of the Establishment of a Scientific
Prize by the late Alexander Keith, Esq. of
Dunottar. Jn a Letter from the Trustees to

Sir Walter Scott, Bart, P, R. S. E. =

PART SECOND.

XIX. On the Mineralogy of Disko Island. By Sir
Charles Giesecke’, F. R. S. Edin. M. R. I. A,
Professor of Mineralogy to the Royal Dub-
lin Society, and Member of the Royal So-
cieties of Copenhagen, Upsal, &c. &c.

XX. On the Nature and History of the Marsh Poi-
son. By William Fergusson, M. D. F. B.S.
bh Edin. Inspector of Army-Hospitals,

XXt Description of some remarkable Atmospheric Re-
# flections and Refractions,observed in the Green-
~ land Sea. By William Scoresby, Esq. junior,
F,R.S. Edin., . f a

XXII.

ili

Page

235

239

243

259

273

299

iv CONTENTS.

XXII. Account of the Erection of a Granite Obelisk,
of a single Stone, about seventy feet high, at

Seringapatam. By Alexander Kennedy, M.D.

F. BR, S. Edin. &e. Z es

X XIII. Account of a Remarkable Structure in Apophyl-
lite, with Observations on the Optical Pecu-
liarities of that Mineral. By David Brewster,
LL. D. F.R.S,. Lond. & Sec. R. S. Edin.

XXIV. On the Application of Analysis to the Discove-
ry of Local Theorems and Porisms. By
Charles Babbage; Esq. F. R. S. Lond. & Edin.

XXV. Observations on the Errors in the Sea-Rates of
Chronometers, arising from the Magnetism of
their Balances; with Suggestions for removing
this source of Error. By William Scoresby,
Esq. junior, F. R. 8. Edin. - -

XXVI. Report on a Communication from Dr Dyce of
Aberdeen, to the Royal Society of Edinburgh,
“ On Uterine Irritation, and its Effects on
the Female Constitution.” By H. <a
M. D. F. R. S. Edin. -

XXVII. Description of some Indian Idols in the We
seum of the Society. By W. A. Cadell, rt
F.R.S. Lond. & Edin. -

XXVIII. Observations on the Formation of the Chath
Strata, and on the Structure of the Belemnite.
By Thomas Allan, Esq. F.R.S. Lond. & Edin.

XXIX. On a Submarine Forest in the Frith of Tay,

with Observations on the formation of Sub- —

marine Forests in general. By John Fleming,
D. D. F. B.S. Edin. -
XXX. Description of a Monochromatic Lamp for
Microscopical purposes, §c. with Remarks on
the

Page

307

317

337

353

365

381

393

m9

CONTENTS.

the Absorption of the Prismatic Rays by co-

loured Media. .By David. Brewster, LL. D.

_ F.R.S. Lond. & Sec. R. S. Edin. Pee
XXXI. On the Absorption of Light by Coloured Me-
| dia, and on the Colours of the Prismatic Spec-
trum exhibited by certain Flames; with an
Account of a ready Mode of determining the
absolute dispersive Power of any Medium, by

| direct experiment. By J. F. W. Herschel,
i a,

Esq. F. BR. S. Lond. & Edin. In a Letter to
Dr Brewster, a -

' r" XXXIL On the Mineralogy of the Faroe Islands. By

W. C. Trevelyan, Esq. F. R. 8. Edin.,

Pi a
| * XXXUL Electro-Magnetic Experiments and Obser-
cee.

we, F. R. S. Edin. & William Scoresby, Esq. jun.,

vations. By Thomas Stewart Traill, M. D.

Pin, Pe Lond. & Edin., -

XXXIV. Conjectures on the Analogy observed in the
Formation of some of the Tenses of the Greek
Verb. By John Hunter, LL. D. Professor
of Humanity in the University of St An-
drew’s, - -

*

ae

History oF THE Society, . 2 _

Laws of the Society, enacted 23d May 1811, 26th Fe-
bruary 1820, and 24th January 1823, -

List of the Office-Bearers and Members elected between
January 26. 1818, and March 3.1823, - -
‘

List of the present Ordinary Members of the Society, m
the order of their election, = = =

List

445

481

493

495

503

51%

vi CONTENTS.

List of Non-resident and Foreign Members, elected under +
the old laws, - - - 524
List of Honorary and Foreign Members, elected under the
new laws, - - - 525
List of Members deceased from 1799 to March 1. 1823, 527
Donations received by the Society since 1811, - 530.4
;

I. On the Parallel Roads of Lochaber. By Tuomas Lauper
Dick, Esa. F. R. S. Epi.

(Read March 2. 1818.)

I Hap last winter the honour of laying before the Royal So-
ciety a few hasty remarks on what are called the Parallel
Roads of Glen Roy, suggested to me by an accidental ramble
through that valley, in the course of a pedestrian tour in the
West Highlands,’ during the previous August. My curiosity
having been much excited by what I then saw, I was induced
to revisit the highly interesting district of Lochaber, in the be-
ginning of last June, and had thus an opportunity of devoting
three whole days to a more complete inspection of these re-
markable shelves, which I was surprised to find, were to be
traced through a much more extensive stretch of country than
former observation had led me to imagine. My first visit to
Glen Roy was accidental ; but upon this late occasion, I went
with the purpose of endeavouring to put myself in possession
of all the facts I could possibly collect, regarding these curious
appearances ; and in doing this, I had several advantages which
I did not formerly enjoy. I was accompanied by my friend
Mr Macrxay, civil engineer, who kindly assisted me in ascer-

VOL. IX. P. I. A taining

2 ON THE PARALLEL ROADS

taining the horizontality of the lines. The weather was par-
ticularly favourable for our purpose, having been remarkably
calm and clear during the whole of our stay in Lochaber. We
had also the good fortune to be hospitably received, as the
guests of Mr Macpone.u of Inch, whose residence, situated
near the junction of the rivers Roy and Spean, afforded us the
most centrical point, from whence we might make excursions
in every direction ; whilst extreme acuteness of observation in
our host, and the great interest he has taken for many years, in
the very investigation in which we were engaged, and the con-
stant opportunity he has had of making himself acquainted with
the various appearances, rendered him an intelligent, as well as
a willing guide. Iam, therefore, now enabled to offer an ac-
count of these shelves, not only much more particular, but
embracing a much greater extent of country. And although
I am well aware of the numerous sources of error to which the
investigator of so many intricate mazes is exposed, yet I trust
I may venture to hope, that my inaccuracies are few in num-
ber, and, individually, unimportant. In this hope Iam the more
confident, from having the highly valuable testimony of Mr
Macponett of Inch to support me, from whose communica-
tions I have even described some particular spots, which I had
not an opportunity of visiting in person. Indeed I cannot suf-
ficiently express my sense of the obligations I owe to that gen-
tleman..
In the first part of my essay, I propose to give a general
description of the form and appearance of the shelves. I shall
next suggest the theory, which may account for the formation
of such appearances in general. I shall then give a particular
account of the whole shelves of Lochaber, as connected with the
topography of the glens where they are found. And, lastly, I

shall conclude, by stating the theory, which appears to me most
likely

OF LOCHABER. 3

likely to explain the circumstances of their particular forma-
tion. My remarks will, I hope, be found more intelligible, by
reference to a map, which, however, must be considered as a
mere eye-sketch of the country, its construction having been
merely aided by the observation of a few angles and bearings,
and therefore having no pretensions to geographical accuracy,
beyond what is necessary for the purpose to which it is de-
dicated,—that of giving an idea of the courses of the dif
ferent shelves, to which I have affixed distinguishing fi-
gures. Though the shelves are laid down in continuous
lines, it is by no means meant to convey the idea, that
they are strictly so in reality: partial deficiencies in their con-
tinuity are certainly to be observed, but these are too trifling
and unimportant, to be noticed in a general view of them on
so small a scale. It should be also remembered, that it is on-
ly in the most important points, that the detail of their vari-
ous lesser bendings is attended to. Where such a point oc-
curs, as at the head of Lower Glen Roy, the attention which
has been paid to mark the sinuosity of the lines, as correctly
as possible, has compelled me to devote more room to that
part, than it would be entitled to were strict proportion obser-
ved; and thus Upper Glen Roy is more reduced in size than
it ought otherwise to have been. Besides the map, I have ven-
tured to give a few sketches of what appeared to me to be the
most remarkable views of the shelves. These are taken from
above, or on the same level with them, so as to produce that
natural rise of the perspective, observable in the lines of level
water. Without this, it is not easy to comprehend their hori-
zontality from a drawing. This, however, lends them the cha-
racter of bird’s-eye views, and consequently gives a more con-
fined appearance to the glens than they present when seen
from below. There are also two plates of diagrams, which
may be found useful in illustrating the theory of their for-
mation.

ag GENERAL

4 ON THE PARALLEL ROADS

General Appearance and Character of the Shelves.

Tue shelves run in a series of horizontal lines, along the-
sides or faces of the mountains of Lochaber *, bounding the
valleys of Glen Gluoy, Glen Roy, Glen Spean, and several of
their smaller tributary glens. One range of these is to be ob-
served on each side of Glen Gluoy, running at a level some-
what higher than that of any of the linear appearances in the
other glens, with none of which it has the least connection.
In Glen Roy there are three corresponding ranges, the upper-
most being at a level about 12 feet under that of the shelf in
Glen Gluoy. The next is about 80 feet below the level of the
one immediately over it ; and the lowest line of all, is about 200
feet underneath that to which it succeeds in elevation. These
two last measurements, however, are merely such as could be
accomplished by an ascertainment of the distance of each range
from that above it, at different parts of the glen, corrected by
a calculation of the intensity of the various slopes, producing
an approximation to the truth. The two uppermost shelves
of Glen Roy are entirely confined to that valley, and those
immediately tributary to it; but the lowest of all, is seen to

sweep

* The Gaelic word Lochaber, signifies the influx of a lake into a river, or the
sea. The district so called, comprehends Glens Gluoy, Roy, and Spean, Lochs
Laggan and Treig; and the country stretching in the direction of Fort William,
and as far to the westward as the Ferry of Balachulish.

OF LOCHABER- 5

sweep out to right and left, from its mouth into Glen Spean ;
. running on the one hand, by various sinuosities, in the direc-
tion of Highbridge, and extending up the north side of Glen
Spean, and round the upper extremity of Loch Laggan,
whence it returns on the south side of the same valley. There
are thus four distinct ranges of these shelves, which, to avoid
circumlocution, and for the sake of greater perspicuity, I shall
uniformly number from above downwards. I shall, therefore,
call that having the highest level, and belonging exclusively to
Glen Gluoy, Shelf 1st; those two coming next in elevation,
and which are to be found in Glen Roy alone, I shall call
Shelf 2d and Shelf 3d; and, lastly, That which is lowest, and
which being common to both Glen Roy and Glen Spean, is
by far the most extensive, I shall designate as Shelf 4th. All
these will be found in the map, with their respective numbers
attached to them. There are also some other indications, in
the bottom of Glen Spean, to be afterwards described, to.
which, as they appear to owe their formation to causes similar
to those of the shelves above mentioned, I have affixed the
numbers 5, 6, and 7. All these different shelves are found to
maintain the horizontality characterizing the surface of water,
throughout all the various windings of their lmear extent, and
round the hollows and projections of the hills, whether these
are small or great, sudden or otherwise ; and each respective
range, on one side of any of the glens, is exactly on the same
level with that corresponding to it on the opposite side. In-
deed these lines, which are thus of similar level on different
sides of the glens, are manifestly identified. For whenever
the level of the bottom of a glen, by rising above that of any
one particular shelf, obstructs its farther progress upwards, that
shelf immediately winds round, and crosses the bottom of the val-
ley on the same level, in the form of a broad shelving plain,
whence

6 ON THE PARALLEL ROADS

whence returning downwards on the other side, it produces,
when opposed to that part of it running upwards, the appear-
ance of two twin shelves, when, in reality, they are discovered
by examination to be one continuous line. There is, of
course, every where, a perfect sameness in the perpendicu-
lar height of one range above that which is beneath it. But
a deception is produced to the eye, with regard to the appa-
rent relation of the whole shelves, to the valleys where they lie.
For, from the inclination of the bottom of the valleys, being
opposed to the perfect horizontality of the shelves, the whole
of the latter have the deceitful appearance of sinking on the
sides of the hills, as they run in a direction towards the sour-
ces of the streams; and of rising, as they approach the open-
ings of the several glens. Although the perfect linear hori-
zontality of these shelves, and the correspondence as to level,
of each particular part of a shelf, on the two sides of the same
glen, has been always admitted, upon simple ocular inspection,
yet it is by no means easy to put this important matter beyond
doubt. It is indeed impossible to perform a mathematically
accurate levelling process, on such rude and indefinite subjects
as these shelves are. For although they appear very distinct-
ly, and even sharply marked, when viewed from the glen below,
or from some distance, yet when the observer climbs up to in-
spect them more narrowly, he always finds it impracticable to
discover their precise limits, and they are then indeed so very
indistinct, that he may even be actually treading on a shelf,
without being in the least aware that he is doing so. This
shows how very imperfect they are as to form, and how very
little they deviate from the ordinary contour of the hills along
which they are traced; for whilst their outward edge is very
much rounded off, they are united interiorly to the acclivity of
the mountain above them, by a highly inclined slope, so as to

make

OF LOCHABER. 7

make the section of the line of their profile somewhat like .
‘this :

And every part of the breadth of the shelf also, deviates so far
from the level, that the sections of it would exhibit an inclina-
tion outwards of from one foot in five, to one foot in three,
and in some places a great deal more. Their actual surfaces
are all so rugged and irregular, that no proper series of opera-
tions could be carried along any of them, with a hope of de-
termining their true linear level. My friend Mr Macrean
and I, therefore, conceived that we did nearly all that could be
well accomplished for this purpose, by using the following
means, in the course of three several observations, taken on
shelf 2d, shelf 3d, and shelf 4th, which, together with the re-
sults, I shall now detail.

It was from a very commanding position, marked d on the
map, that we levelled shelf 2d. From this point we enjoyed
_ very nearly the same view as that represented in plate IV., and
had the advantage of observing some considerable portions of
the same shelf on the other side of the valley, immediately op-
posite to the eye, and at no great distance from it, whilst there

were also a variety of different distances, receding in perspec- |
tive behind one another. We employed a very delicate eigh-
teen

8 ON THE PARALLEL ROADS

teen inch levelling instrument, made by Jones. It was plant-
ed, as nearly as we could guess, (where the limits of the sub-
ject we had to work upon were so ill defined,) rather towards
the lower edge of the shelf, and we endeavoured to adjust it in
such a manner, as to make the levelling telescope itself of the
same height with what we supposed to be the higher or inte-
rior angle of the shelf. Directing the object-glass of the in-
strument to the nearer and immediately opposite correspond-
ing line of shelf, it applied all along, most accurately, to the
horizontal hair ; but when pointed to those farther off, (some
of which were perhaps five or six miles distant,) they appear-
ed to sink sensibly below the hair, and this in proportion to
their distance from the point where we stood; but they were
nowhere observed to do so in a greater ratio, than the allowance
for the curvature of the earth at such rectilineal distances de-
manded. And, what was in our opinion most conclusive,
when the telescope was pointed to, and made to traverse along
any particular portion, which, from being directly opposite to
the eye, might have been presumed to be nearly equidistant
in all its parts, it was found to preserve an uniform relation to
the horizontal hair.

Our observation taken on shelf 3d, was, if possible, even
more satisfactory, from the point we chose, (see f in the map,)
being still better adapted for the purpose, as we not only com-
manded a view of the head of what may be termed Lower
Glen Roy, (see plate V., the sketch for which was taken from
hence,) but we could also see the shelves, running continuous
all the way down to the mouth of Glen Turret, to which we
were opposite. We could follow them with the eye throughout
the greater part of their progress around that tributary glen,
and so down the north-west side of Glen Roy, for a con-
siderable distance ; forming altogether a line, which, if it had

been

OF LOCHABER. 9

been extended, would have stretched perhaps five or six miles,
whilst, from its numerous bendings, the rectilineal distance of
the farthest visible part of it from the eye, was probably not
so much as two miles, and most of it was greatly less than one.
And what was still more advantageous in this position, in tra-
versing the telescope of the instrument round, many points
could be touched upon which were evidently nearly equidistant
from the eye. Here the perfect coincidence of the line with the
horizontal hair, was more generally striking than it was in our
first. experiment.

Our third trial was on shelf 4th, and we were fortunate in
selecting a very excellent point of view for that also. The
spot where we planted our instrument was a little to the east-
ward of the house of Inch, on the south side of the entrance
of Glen Spean, (see 6 in the map). It was from thence that
I sketched the view of the entrances of Glen Roy and Glen
Spean, as represented in Plate II., which, when compared with
the map itself, will afford some idea of the great extent of
shelf 4th, which we commanded at one coup d’eil. We could
trace it, sweeping from Ben-y-vaan on the left, up Glen Col-
lerig,—returning from that little valley, and embracing the
south side of the round hill of Bohuntine, and disappearing
into Glen Roy,—re-appearing on the faces of its southern
mountains, till it is again lost behind that of Crag-dhu, which
divides the entrances of the two glens,—coming into view
again as it circles round the bottom of that projection, and
identifying itself with the upper line of a high inclined plane,
whence it sweeps into the mouth of Glen Spean, where we
could of course trace it much farther, than could be embraced
within the angle of vision employed in the delineation of a
perspective sketch. We could also trace the same line faintly
encircling the isolated rock of Mealderry, which appears in
the drawing much nearer the eye. We traversed the telescope

VOL, IX. Ps I, B of

10 ON THE PARALLEL ROADS

of the instrument around all these different points, and the re-
sults were perfectly satisfactory. In short, from all our expe-
riments, and from all our other observations, there did not re-
main a shadow of doubt in our minds, that the whole of these
shelves were perfectly horizontal in themselves, and that eve-
ry part of any shelf on one side of a glen, was decidedly of the
same level with the corresponding portion of it on the other
side.

The breadth, or depth of these shelves, on the steep sides of
the hills, is very various, and is evidently much modified by
circumstances, particularly by the nature of the ground. That
part of the shelf is generally deepest, and most strongly mark-
ed, where the face of the mountain forms an acute angle, or
rounded promontory ; and this is more particularly the case,
where the promontory is of comparatively soft materials. In
all other places, whether bay or projection, where the surface
of the hill is soft, and easily worn away, the indentation is al-
most uniformly better defined than where a harder soil occurs.
Where rock maniiests itself, little more generally appears than
a slight tracing on its surface, merely enabling the eye to fol-
low out the line with difficulty; but on the fronts of many of
the rocks, all appearance of it is lost for a space, until it
again manifests itself on the softer surface. The indentation
of shelf 4th, on the rocks at the entrance to Loch Treig, is pe-
culiarly strongly marked; and the same shelf is also well defi-
ned in its circle round the top of Tom-na-Fersit, a small isola-
ted hill near the same point; but these form, perhaps, the
only striking exceptions to what may certainly be considered
as a general fact.

These remarks, apply rather to the degree of distinctness
with which the shelves are traced along the length of the glens
on the steep sides of the flanking mountains, than to their ac-
tual breadth. For when any one shelf approaches the point,
where, (by the rising of the level of the bottom of the valley)

it

OF LOCHABER,. 11

it is compelled to cross to the other side, the breadth of it is al-
ways greatly expanded, so as to give it the appearance of a
broad inclined plane, in some instances so much as half a
mile, or perhaps even a mile wide; and this is almost invari-
ably covered, to a certain depth, with a stratum of peat-moss.
In such cases, the level of the linear appearance infallibly ap-
plies to the upper bounding line of the expanded inclined
plane. These expansions of the shelves, are not only to be
met with in those places, where they cross from one side of a
valley to the other, but are also to be observed in many other
parts of their course, particularly where the hills are low, and
of a gentle slope, or rather where the shelves run along the
bottom of such hills. On a first hasty observation, these ex-
pansions may be overlooked, as having nothing to do with the
shelves, and it may be supposed, that some cause has here
operated to interrupt them for atime. But a little attention
to their appearance and level, will at once show, that these
inclined planes. have been formed by the same cause, as the
more properly defined shelves, and that they are in fact no-
thing more than expanded continuations of them, which, from
the very circumstance of their greater breadth, lose that ex-
tremely sharp and striking appearance, so remarkable in those
parts where the hills are steeper and more lofty.

The shelves are in many places covered with large masses
of stone, some of them many tons in weight, lying for the
most part quite detached on the surface, and having their acu-
ter angles rounded off in the greater number of instances; in
short, in every respect resembling those fragments generally
found strewed on the margin, and in the shallow edge of al-
pine lakes. In some places, where the stones are large, and
the shelf narrow, a single block covers its whole breadth.
Where rock appears any where on a shelf, its angles are also

for the most part rounded. One fact is very important, and
: B2 deserves

12 ON THE PARALLEL ROADS

deserves particular notice: the nature of the soil in each val-
ley, is materially different above and below its highest line of
shelf; all above this natural division, being found to resemble
the bare moorish soil covering any other mountain; whilst
large depositions of alluvial clay, sand, rounded pebbles, and
gravel, present themselves every where below that point, and
this, more particularly towards the mouths of the different val-
leys. Marine exuvize, however, are nowhere to be met with.
Perhaps the most interesting circumstance regarding these
shelves, is, that wherever an isolated little hill happens to rise
from the bottom of the valley to a height above that of the
level of any shelf, a delineation runs round the little hill, at
a level corresponding to that of the shelf on the mountains of
the side of the glen.

Such, then, is the general description of the character and
appearance of these shelves.

Theory which may account for the formation of Shelves running

horizontally along the sides of Mountains confining Glens.

Ly the total obscurity in which the origin of these singular
shelves is involved, some have been inclined to regard them as
productions of art, others as the work of Nature. Of these two
opinions, I confess I cannot hesitate in rejecting the first. The
immensely arduous nature of the undertaking, arising not on-
ly from its extent, but from the numbers of accurate: measure-
ments and levellings it must have required,—the impossibility
of the supposition, that the engineers of those early times to
which they must be referred, could have known how to make
the exact allowance for the curvature of the earth, and this,

too,

OF LOCHABER. 13

too, at a period when our planet was believed to be a plain,
extending ad infinitum ;—the difficulty of imagining any ra-
tional object for the construction, in such a situation, of such
a series of terraces, so precisely horizontal, so equidistant in
all their parts, and so exactly corresponding on the two oppo-
site sides of the valley, and in some places sweeping in one
continued circle round the tops of detached hills in the middle
of the glens ;—above all, the actual structure of these shelves, as
they at present remain, constitute, in my mind, insurmount-
able objections to any hypothesis, which would ascribe their
origin to human labour and ingenuity *.

That

* « As there is nothing left upon record,” says the Reverend Mr Ross, in his
account of the parish of Kilmanivaig, (Statistical Account of Scotland, vol. xvii.
p. 549.) “ respecting the times when, the persons by whom, or the purposes for
*« which, these roads were constructed, we can only mention the common traditions
“ regarding them. One is, that they were made by the Kings of Scotland when
‘© the royal residence was in the castle of Inverlochy, which is not above eleven
** miles from the nearest of them; and, what gives an appearance of truth to this
“ tradition, in the opinion of those who maintain it, is, that the construction of
*¢ these roads was so vast an undertaking, as could not be effected by any vassal or
- nobleman, however powerful. Another. tradition, which is that of the natives,
‘© is, that they were made by the Fingalians, and, under the name of Fingalian
* Roads, they are still known in, this country. 'They are likewise called the Ca-
“© san, i. e. the Roads, by way of eminence. Of this the natives are convinced
s* from this circumstance, that several of the hills of this glen have retained, from

_ “ time immemorial, the names of some of the heroes of Fingal, such as the Hill of
* Gaul the son of Morni; that of Diarmid; and of Fillan ; and likewise of Bran,
“ the famous dog of Fingal, &c. Now the popular belief cannot be considered as
“ a direct proof of any opinion, yet we cannot help remarking, that the original
“ tradition, (which in this case has been always invariable,) gives a strong degree
“< of credibility to the existence of such heroes, and renders it by no means impro-
bable, that these extraordinary roads have been the result of their labours. The

’ § purpose which they were designed to serve, seems to have been, (agreeably to

* the common opinion,) to facilitate the exercise of hunting ; for in ancient times,

“ and,

14 ON THE PARALLEL ROADS

That theory seems to me infinitely the most probable, which
attributes the formation of the shelves to the action of the wa-
ters of a lake. The perfect horizontality of the lines, and their
exact agreement in height on the opposite mountains, added
to the fact of their running up the smaller tributary glens, and
following the retiring, as well as the projecting parts of the fa-
ces of the mountains, with so much regularity and precision,
—the circumstance of their encircling isolated hills with a per-
fect ring, totally unconnected with any other part of the
shelves,—the rounded edges of the rocks, and fragments on
their lines,—the change which takes place in the soil above
and below the shelves,—their expansion into mossy flats or in-
clined planes, whenever the level forces them to do so, —all
combine to show, that nothing but the surface of water could
have caused them. That alpine lakes, filling deep hollows
amidst mountains, rising from their bottoms with steep and al-
most precipitous acclivities, do generally form similar shelves
around their margins, must be sufficiently well known to eve-
ry one who has had an opportunity of visiting such scenes,
Indeed a little reflection will show, that this must necessarily
happen. For if we suppose the almost perpendicular sides of
such a hollow to be filled, to a considerable height, with a lake
of this character, as exemplified in the diagram, (Plate VII.
fig. 5s)y in which the dotted line A represents its level, then

the

‘* and, indeed, till within this century, the valley was covered with wood, which
* made it very difficult to pursue the deer, &c. and rendered certain avenues ne-
cessary for effecting this purpose; in corroboration of which opinion, it may be
observed, that upon the sides of the roads, there have been found some stakes
fixed in the ground, probably the remains of some of the paling or fences, which
in those days were made use of to confine the game, till they were driven in

upon a field, called Dal-na-sealg, or Hunting viene where the presumption is
** they were killed.”

OF LOCHABER. 15

the agitation of the surface of this lake, by the various winds
to which it may be exposed, will naturally drive its waves
against some of the points round its margin, as @a, and will
gradually eat away the bank there by the frequency of their
action against it; whilst all being still underneath, it will not
be affected any where below. ‘Then, as the water thus. mines
away the banks, where they are on a level with its surface, the
earth and other materials will naturally fall down from above, ~
so as to form two sloping cuts or notches in the side of the
hill, as represented by BB, between the dotted and black lines.
All the smaller and less. ponderous substances, such as gravel,
earth, and sand, will of course be washed inwards, towards the
deeper part of the lake, and immediately on getting beyond
the shallow, will sink down, and form an accumulation at the
bottom, and on the sides, as represented in the diagram by D,
between the dotted and black lines. But the violence of the
waves of a lake, is seldom such as to move those Jarge masses
of stone that may be supposed to be uncovered, loosened, or
undermined, and brought down by the almost continual,
though gentle, fluctuation of its surface towards its shores.
These, therefore, would gradually accumulate on its shelving
beach. It is almost unnecessary to add, that the breadth of
the shelves (BB in the diagram) would vary according to the
degree of hardness or softness of the materials forming the va-
rious parts of the bank on which the water would have to
operate; and that where stubborn rock should present itself,
unless it were placed in some peculiarly exposed situation, it
might remain for ages, hardly, if it all affected. Wherever
there were swells or promontories, these would in general be
most acted upon by the agency of the waves, unless other cir-
cumstances should prevent it. This is, indeed, the precise
character of all, mountain lakes, filling hollows between very
steep

16 ON THE PARALLEL ROADS

steep acclivities, like those I have supposed. I should have
little difficulty in enumerating many such pieces of water. In
the earlier part of the very tour which ultimately led to my
first visit to Glen Roy, our party accomplished a rather ardu-
ous expedition to Loch Aven, a lake very much answering
the above description. It is situated in the very bosom of the
Cairngorum range of mountains, having that which is more
properly called Cairngorum rising on its western side, directly
from its waves, almost to the utmost height of the mountain ;
and on the south-eastern’ side Ben-mach-duie, the highest
point of the whole chain, is seen elevating itself equally sud-
denly, and with a rocky, and almost overhanging front, still
grander and more abrupt. This lonely lake presents an as-
semblage of every thing that is wild and sublime in Scottish
scenery. ‘The gentlemen of our party who were familiar with
the ruder parts of the Swiss Alps, admitted that Loch Aven
furnished no very insignificant specimen of the terrific scenery
to be met with in that interesting country ; and the resem-
blance was rendered more striking, when we saw it, on the Ist
of August, from an immense unmelted glacier, which shone
through the thin mist floating on the brow of the rocks, at the
farther extremity of the lake. Mr Rosson, who, in his
«“ Sketches of the Grampians,” has given a very faithful out-
line of it, is, I believe, the only person who has had the merit
of noticing this desert and desolate, but magnificently gloomy
spot. As we climbed the rugged, and almost inaccessible front
of one of the crags, rearing itself over its upper extremity, by
a pass which ascended between two torrents, precipitating
themselves with dreadful roar from the glacier on the brow of
the mountain above us, | could distinctly perceive, when look-
ing downwards to the lake, that a narrow shallow shelf almost
every where surrounded it, within which it seemed, by its sud-

den

OF LOCHABER, 17

den change of appearance and colour, from an extremely green
transparency, to a pitchy blackness, to become all at once of
an apparently unfathomable depth. This circumstance, which
I remarked at a moment when I had not even a thought of
Glen Roy, struck me very forcibly. But I had afterwards oc-
casion to notice, during the remainder of the same tour, that
such was almost invariably the case with those lakes having
steep shores of the same description. In Loch Lochy, Loch
~Qich, and Loch Ness, wherever the mountains rose from a
depth with a sudden acclivity, the same appearances presented
themselves. And what appeared more extraordinary, and
what I scarcely expected, in sailing down the salt-water lake
or arm of the sea called Loch Linnhe, from Fort William to-
wards Coran Ferry, we even found the same kind of shelf in
similar circumstances on its southern side, though on a larger
and ruder scale. Since that time, I have had occasion to make
the same remark, where the hills rise abruptly from Loch Awe,
Loch Lomond, Loch Tay, and almost every other Highland
lake that I have visited. Most of the mountain lakes of Swit-
zerland and Italy, having sides of the same precipitous de-
scription, are surrounded by the same shelving margin ; and,
amongst many others, the lakes of Nemi and Albano were
particularized to me by an intelligent friend, as being both of
this character *. But I wish it to be always understood, that
the foregoing illustrations, as well as the diagram to which
I have referred, are merely applicable to the formation of
a shelf on the steep side of a mountain, where, though it
may not be found so broad as in other places, it will al-
ways be more sharply marked than when the waves are

VOL. 1X. P. I. G expended

* Since this paper was presented to the Society, I have had an opportunity of
satisfymg myself of the accuracy of this remark with regard to these lakes, as
well as of adding to the examples of this general fact, from my own personal ob-
servations on the lakes of Maggiore, Lugano, and Como, as well as in the upper

_ part of the Lake of Geneva, and several other continental lakes, having precipitous
shores. ;

i8 ON THE PARALLEL ROADS

expended on a more gentle slope, where they will produce
shelves less distinctly indented indeed, but much broad-
er. The number of lakes which furnish examples of these
broad shallows within the margin, where they have easi-
ly inclined shores, is so great as to render it unnecessary to
instance any of them. This last remark, however, should be
kept in view, because it will be found to apply to many parts
of the particular description of the courses of these Lochaber
shelves, which it is my intention to give, and will more espe-
cially explain those parts of them, where an inattentive observer
would be apt to suppose that they disappear entirely, when, in
reality, they only become less distinct, by becoming wider,
and consequently more gradually shelving.

After subjecting mountain lakes to this close investigation, it
will probably strike every one, that the consequence of the
sudden escape of the water from one of them, would be the
immediate appearance of a glen having a range of horizontal
shelf, traced high up on the face of its mountains, and in every
respect similar to those exhibited in Lochaber ; and this would
be either distinctly seen all around it, or would appear only
partially, as the nature of the different parts of the sides of the
hills happened to be more or less obdurate or friable, and
would present all the modifications of breadth, that might have
been occasioned by their various degrees of slope, as well as by
their numerous promontories, swells, hollows, or bendings.
Through the kindness of a friend, who was one of the party in
my first visit to Glen Roy, and who is well acquainted with
the spot I am now about to describe, I am fortunate in ha-
_ ving it inmy power to produce a case exactly of this descrip-
tion, where there cannot be a doubt that such an escape of the
waters of a lake did unquestionably happen, although the ex-
act time when, and the actual manner how it occurred, is lost in
the obscurity of the dark ages. The valley to which I allude is si-
tuated a little above the town of Subiaco in Italy, lying about
forty-six miles to the eastward of Rome, and twenty-eight

from

OF LOCHABER. 19

from Tivoli. The river running through the valley nearly retains
its ancient name, being there called the Aniene; but as it ap-
proaches Tivoli, it takes the more modern appellation of the
Teverone. Subiaco is an Italian corruption of Sublaqueum,
by which name it was anciently known. Following the course
of the river upwards from Subiaco, the mountains, which ere
part of the Appennines, and of very considerable height, begin
to close around, confining the bottom into a narrow glen; and
in about half-a-mile after leaving the town, the valley is obser-
ved to be blocked up all at once, by an immense wall of rock,
perhaps 100 feet high, crossing it at right angles, (see Plate VII.
fig. 1. and fig. 4. A). This appears rent perpendicularly from
top to bottom in the centre, as if by some unaccountable con-
vulsion, presenting a chasm, which is only 12 or 15 feet wide,
and -which it is quite impracticable to enter, as the bottom is
filled by the river, which is, indeed, very much confined in its
passage through it. This natural barrier of rock, is perhaps not
less than an hundred yards in thickness, and although it is
quite perpendicular towards Subiaco, it has a slope towards
the other side, which faces up the river. The sketch of it,
(Plate VII. fig. 1.) was drawn from an outline done by my
friend from recollection, and is sufficiently accurate to give
some notion of this singular rock, at least as far as regards ©
the present purpose; and the perpendicular section of it,
(Plate VII. fig. 2.), supposed:to be made on the same line
with the ravine, gives an idea of both its steep and its
sloping side. The plan of the valley, (Fig. 4.), although it
is drawn from a mere sketch from memory, by the same gen-
tleman, will illustrate the description. Having got beyond the
rocky wall, (marked A, fig. 4.), the glen to which I wish to
solicit attention, is found to be deep and narrow, and about a
mile in length. The river Aniene runs along in the bottom,
and the mountains on either side rise immediately from its
margin, and, with a very sudden arid steep acclivity, as is re-

c2 presented

20 ON THE PARALLEL ROADS

presented in a section of the valley, supposed to be taken
across from B to E of the plan, and given in fig 3., in which
G represents the river. High up, on the face of the hills on
the south side of the valley, are the remains of the Baths of
Nero, (E in the plan, fig. 4. and section, fig. 3.), and the re-
mains of the mouth of the Aqueduct by which Arrrus Crav-
pius conveyed water into Rome, from the lake, which origi-
nally filled the valley to that height, (F, fig. 4.) On a level
with these, and consequently on a level with the ancient lake,
an exact, and perfectly horizontal shelf, in every respect resem-
bling those of Lochaber, runs around the face of the hills on
the southern side of the valley, as expressed by the dotted
line, fig. 4. But on the northern side, (where B, fig. 4. marks
the situation of the convent of Santa Scholastica, and C that
of San Benedetto), there is a great deal of rock, and conse-
quently no such appearance of a shelf is to be observed. At
the head, or western extremity of the valley, (D, fig. 4.) the
river enters it through a ravine, by rapids, and over a cascade.
Such is a description of the present state of this singular spot,
to which I must beg particular attention, as it will be found
to have a wonderful resemblance, in all its parts, to some of
the appearances, to be described in the sequel of this paper.
The Valley of Subiaco was anciently filled with part of the Sim-
bruina Stagna ; and the name of Sublacum was given to the an-
cient town, from the circumstance of its being situated under the
lake. Of the Simbruina Stagna, anciently three in number, none.
are now remaining. This was the lowest ; the other two were
formed by the river higher up, and it is very probable, that
some interesting appearances, of a similar nature to those I
have been describing, may likewise exist on the sides of the
hills which served formerly to confine them. | But the banks
of the Aniene are little known above the valley of Subiaco,
the country being so overrun. with banditti, that there is no
safe travelling beyond the Convent of San Benedetto, where,
indeed, the regular road stops. These lakes are more than

once

OF LOCHABER. 21

‘ once mentioned in the classics, particularly by Tacitus, who
notices the fact of Crauprus’s aqueduct having its origin on
the hills on their margin; “ fontesque aquarum ab Simbrui-
“ nis collibus deductos, urbi intulit,’ (Ann. lib. xi. cap. 13.) ;
and the circumstance of Nero, who had a villa there, having
made it an occasional residence, is also established by the same
historian, who mentions the fact of that Emperor having been
alarmed by prodigies whilst in that retreat: “ Nam quia dis-
** cumbentis Neronis apud Simbruina Stagna cui Sublaqueum
“ nomen est, ictu dape mensaque disjecta erat,” (Ann. lib. xiv.
cap. 22.) The remains of the baths of Nero, E, fig, 4. Pl. VII.
and the mouth of the Claudian aqueduct, F, fig. 4, which are
both exactly on the line of shelf running around the face of
the hills on the north side of the valley, and which, happily for.
our illustration, were both of a nature, that rendered water es-
sentially necessary for their several objects, sufficiently prove
that it must have owed its origin to the action of the waves of
the lake, which must have had its margin there, (as at E, fig 3.,
where BE represents its ancient surface), otherwise it is mani-
fest that both those buildings would have been useless. The
wall of rock, (fig. 1.), as described by my friend, is just the
height of the shelf, and composed of what he called “ the na-
“ tive rock,” or that which is every where prevalent in the
neighbourhood. This, we know from Broccu’s late work on
the Geology of the Appennines, is a peculiar sort of lime-
stone, of a pearl-grey, dusky-white, or smoke colour, with a
smooth earthy fracture, without lustre. But what forms a ve-
ry singular and striking physical corroboration of the histori-
cal fact, that the river once ran over the top of this rocky dam,
is, that the upper surface of it, (A, figs. 1, and 2.) is covered
by a formation of the éravertina tufa, which calcareous incrus-
tation must have been deposited there by its waters, when
flowing from the lake at that elevation. The river, as is well
known, continues to deposit the same tufa every where, parti-

cularly

74 ON THE PARALLEL ROADS

cularly at the cascade of Tivoli, where this substance is con-
stantly accumulating *. .

As the ancients mention the existence of the lake, which
once filled the valley of Subiaco, but take no notice of the
cause by the operation of which it was drained, it must have
occurred at some period between the fifth and the fourteenth
centuries. It is as impossible, as it is unnecessary for me, to
offer even a conjecture about the nature of this; but I hope
enough has been established to prove, that the valley of Subi-
aco furnishes a decided and well-authenticated instance of a
range of shelf, in every respect like those of Lochaber, and
' which has been unquestionably formed by the waters of a lake.
From the particular description I am to give, it will appear
that the resemblance between the Glen of Subiaco and those
of Lochaber, is rendered extremely strong by a number of cir-
cumstances, common to all of them; perhaps the most re-
markable of these is, that the waterfalls and ravines of Su-
biaco, are also found placed in similar situations in the Loch-
aber glens.

Particular Description of the Shelves, as connected with the Geo-
graphy of the Country, and the Appearance of the Glens in
which they are found.

I propose to arrange the more particular description of the
shelves, which I am now about to give, in the following order,
which

* When I was lately at Tivoli, I had the most earnest desire to visit Subiaco
in person, not only to make my own observations on the valley, but likewise to en-
joy a range of scenery, described to me as being of the most romantic character ;
but I regret to say, that a variety of circumstances compelled me to abandon the
attempt, with very great reluctance. I had, however, some satisfaction, in avail-
ing myself of the opportunity of corroborating the description in the text, by the
testimony of one or two of my Roman friends, who had been at Subiaco.

OF LOCHABER. 23

which will be easily understood from the map. I mean to be-
gin at Lowbridge, and describe the whole of Glen Roy up-
wards. I shall then give a general account of the Glen-mor-
na-Albin, or Great Glen of Scotland, the necessity of which.
will appear, when I come to the theoretical part of my paper.
Proceeding from thence south-westwards, I shall describe the
more open part of the country about the Spean. I shall trace
-Glen Roy upwards to the Loch of Spey ; return to the mouth
of Glen Turret, and describe that valley, and the High Glen
of its little tributary stream upwards, to where it opens at its
north-western extremity into the head of Glen Gluoy. Re-
turning to the mouth of Glen Roy, I shall describe the whole
of Glen Spean, Loch Laggan, and Loch Treig ; and shall con-
clude with a description of those very satisfactory and convin-
cing appearances in the bottom of Glen Spean, which are
numbered in the map with the figures 5, 6, and 7. and which
can be viewed in no other light than as being three inferior
shelves, each successively of lower level than that numbered -
as above it.

The general direction of Glen Gluoy is nearly S. E. and
N. W., and its length is about seven or eight miles. Its
mouth opens into the Great Glen of Scotland at Lowbridge,
and it pours its stream into Loch Lochy, a little way below
that place. The hills bounding Glen Gluoy approach one
another very closely, leaving no more than room for the river
to run in the bottom. They are very lofty and steep, particu-
larly at Lowbridge, over which they rise with a bold front,
there forming the side of the Caledonian. Glen. They are in
general covered with a short grass, and, like all the rest of the
hills in this neighbourhood, afford excellent sheep-pasture.
From the extreme narrowness of this glen, its shelf is not ea-
sily viewed. I am, however, enabled to describe it, by having
paid two visits to the valley, in the course of which, I looked

into

24 ON THE PARALLEL ROADS

into it from th e side of the mountain Ben-y-vaan, guarding its en-
trance on the south,--traversed its whole extent, going up the one
side of the river, and down the other, so as to endeavour to se-
cure the most perfect view of the two corresponding parts of
the shelf;—and looked down its whole length, from a point on
the side of the mountains, at its upper extremity, (see a in the
map), whence an excellent view of it is enjoyed, (see Plate I.)
About three miles up Glen Gluoy, it is joined by a smaller
valley, called Glen Fintack, whence a considerable stream, ha-
ving a short run, pours itself into the Gluoy. Above this, the
glen makes several gentle winds. Shelf 1st, the only one to
be met with in Glen Gluoy, first appears near the top of the
mountain, on the N. W. side of the valley, a considerable way
below that part of it which is opposite to Glen Fintack. The
sides of Ben-y-vaan, which is a long flat-ridged mountain, are
rocky; and the whole sides of Glen Fintack are particular-
ly so, presenting every where a very magnificent enclosure, of
abrupt and perpendicular precipices of great height. I could
not perceive any appearance of the shelf on the S. E. side, un-
til I observed it on the face of the mountain which bends out
from the N. E. side of Glen Fintack, into Glen Gluoy. At
this point there even appears to be some traces of two lines ;
but one of these, I believe the uppermost, is not continued,
and is probably nothing more than an accidental mark on the
angle of the hill. And here I may take the opportunity of of-
fering a caution to future observers, not to decide too hastily
as to such faint appearances, unless in situations where the
probability of their being portions of the shelf is borne out by
a sameness of level. For, aided by fancy, which is always
alive in an investigation of this kind, the eye is very apt to
lead the judgment into error. I may mention, as one very
strong instance of this, that, at one place, on the N. W. side,
and nearer to the upper end of Glen Gluoy, I was for some

time

OF LOCHABER. 25

time led to suppose, that there was decidedly a second line of
shelf, until a more perfect view from the side of the hill di-
rectly opposite, completely satisfied me, that the undermost,
extending only a short way, was neither parallel to that above
it, nor horizontal in itself. On ascending, to take a nearer and
more accurate inspection, of what appeared so very distinctly
marked when viewed from below, I found it to be no other than
a well-trod sheep-track, not more than six inches in breadth ;
whilst the actual shelf itself, from the steepness of this part of
the hill, affords a broader and more perfectly indented speci-
men, and more perfectly defined, than is to be met with in any
other part of the valley. The deception was increased, by a small
patch of heath having been burnt by the shepherds the season
before ; and the line of the sheep-track having arrested the fire,
and prevented it from spreading below it, the linear appear-
ance on the face of the mountain was thereby rendered the
more remarkable.
The bottom of Glen Gluoy rises considerably towards its
upper extremity, which, turning south-eastwards, is rather ex-
_ panded into an amphitheatre ; and from the end of it there is a
vista through another glen, falling towards Glen Turret and
Glen Roy, and which, to mark the difference between it and
those lower-bottomed glens, I have distinguished in the map
by the words High Glen. The shelf having begun on, each
side of Glen Gluoy, at the points already noticed, is very easi-
ly traced almost every where throughout its whole course up-
wards. That part of it on the north side, runs around the se-
micircular boundary of the head of the glen, and just touches
the level of the bottom of the stratum of moss, lying in the
mouth of what I have called the High Glen, which I shall af-
terwards have occasion to describe more particularly. From
this point the shelf bends round to the south side of Glen
VOL. IX. P. I. D _Gluoy,

26 ON THE PARALLEL ROADS

Gluoy, where it expands into a wide inclined plane, and
where it is united to, and identified with, the twin portion of it
coming up on the faces of the hills on that side of the valley.
This broad part of the shelf is about one hundred yards wide,
and presents the abrupt face of a bank to the bottom of the
glen. By an examination of the map, the river Gluoy will be
observed to enter the glen from its southern mountains,
whence it throws itself in a cascade, and falls by a series of ca-
taracts into a very remarkable ravine, dividing the inclined
plane or broad part of the shelf, at right angles to its line of
extent. Throughout the whole length of this singular chasm,
which, though only a few feet wide, is perhaps not less than
fifty or sixty feet deep, the river has worn out a passage on a
level, not much above that of the bottom of the valley, into
which it issues, and where it is almost immediately joined by
a branch coming from the hills to the north. Some little way
below the junction of the two streams, the river begins to lay
bare the rock in its course, which becomes more rugged, as.
it deepens in its progress towards the Great Glen of Scot-
land.
The Glen-mor-na-Albin, or Great Glen of Scotland, enoug
of which is laid down in the accompanying map, to show its
reference to the district under consideration, bisects Scotland
in a straight line, from N. E. to S. W. from the east sea at In-
verness, to the west sea at Fort William. It is narrow
throughout its whole length, seldom much exceeding a mile
in breadth, except where it expands towards the lower end of
Loch Ness. The mountains forming its sides are every where
lofty, abrupt, and precipitous, bearing every appearance of ha~
ving been severed from one another, by some tremendous con-
vulsion of nature. The bottom is chiefly filled by Lochs Ness,
Oich, and Lochy, and has so very small a rise from the two
seas

OF LOCHABER. 27

seas towards the center, that the summit-level, as taken for
the Caledonian Canal, is not more than ninety-four feet above
high-water mark. Where the bottom of the glen is not occu-
pied by the lakes, it is covered to a great depth by alluvial
matter. Even at the summit-level, where the canal is now ex-
cavating to a depth of twenty-five feet, the workmen, after
cutting through a thick stratum of moss, found nothing but
sand, clay, gravel, and rounded stones, the debris of rocks of
the primitive series, nor has the slightest appearance of ma-
rine exuviz been any where discovered. From the Glen-mor-
-na-Albin, several others branch off at considerable angles, and
there are some lesser cracks and ravines of similar bearing to
these dividing the faces of its mountains.

Proceeding from Lowbridge along the road towards Fort
William, the mountain of Ben-y-vaan, on the left hand,
stretches from the mouth of Glen Gluoy, in a S. W. direction,
opposing an abrupt and. rocky face to the Glen-mor-na-Albin,
and terminating suddenly at a point above a mile from High-
bridge, whence it turns back towards the N. E. at an acute
angle, and then begins to form the northern boundary of the
wider and more open country, stretching southwards towards
the Ben Nevis range. The river Spean, issuing from its glen,
and immediately afterwards uniting with the Roy, runs across
a large basin in this open country, in a direction nearly west,
laying bare the rock as it advances, and cutting more and
more deeply as it approaches Highbridge, where the ravine,
having become of great depth, is crossed by the tall pillars and
arches of the picturesque military bridge, which has recei-
ved its name from its remarkable elevation. Through this,
the Spean foams onwards in a series of rapids and cata-
racts, to join the river Lochy. This latter part of its course
divides a range of lesser hills, running from the foot of the

i D2 mountain

28 ; ON THE PARALLEL ROADS

mountain Ben-y-vaan south-westwards, along the side of the
Glen-mor-na-Albin, and, as indicated in the map, sweeping in
a semicircular series of still smaller eminences, combining to
form a rather elevated moor, stretching towards the west-
ern projection of the mountain Aonach-more, where it com-
pletes the inclosure of what may be termed the Basin of the
Spean.

In the neighbourhood of the House of Inch, which is more
than three miles above Highbridge, the mountains on all sides
begin to approach nearer to one another, forming what may be
considered as the proper entrances of Glen Roy and Glen
Spean. The sketch, Plate If. (taken from the hills on the
south side of Glen Spean, at the point marked 4 in the map),
affords a much better general notion of the situation and na-
ture of the mouth of Glen Roy, in relation to that of Glen
Spean, than any words can convey. I may, however, remark
in reference to it, that the mountain Ben-y-vaan, after return-
ing eastward from its angle opposite to Highbridge, opens
backwards towards the north, making room for a pretty consi-
derable, but much elevated valley, called Glen Collarig, lying
between it, and the round hill guarding the western side
of the mouth of Glen Roy. This round hill, which is marked
on the map by its name, The Hill of Bohuntine, is particularly
interesting, owing to a number of circumstances, to be after-
wards noticed. It is isolated from the neighbouring moun-
tains, by Glen Roy making a great and sudden bend around
its base upon the eastern side; on the south and west by Glen
Collarig, and the little stream sent by that valley, through a
deep dell, to join the Roy; and on the north, by the upper
part of Glen Collarig, marked Gap in the map, which forms a
pass into Glen Roy. The bottom of this opening however,
is at a great height above that of Glen Roy, into which it falls

suddenly,

OF LOCHABER. 29

suddenly, having the appearance, when viewed from that val-
ley, of a very singular breach, high up in the sides of its north-
western mountains. When viewed from Glen Collarig, the
Gap appears as in Plate III. fig. 1. (which was slestiches from
point c in the map); and fig. 2. of the same plate, (which was
sketched from the point e in the map), shows its appearance
when looked at from Glen Roy. This Gap, is what, in my
former paper, I had conjectured to have a communication
with Glen Gluoy ; but the description I have just given of Glen
‘ Collarig, shows this notion to have been erroneous. Glen
Gluoy Fees indeed no other communication with Glen Roy,
than by the high glen of Glen Turret, which I shall have oc-
casion to describe afterwards.

The shelf which is marked all along its line with the figure
4 in the map, and which I said I was to designate as shelf 4th,
makes its first appearance high up on the side of Ben-y-vaan,
somewhat more than a mile to the east of Highbridge. From
this point it runs faintly eastward, sweeps up the Glen of Col-
larig, and crosses it just above some cottages, in the form of
an extended mossy flat, or rather gently inclined plane, which
has steep banks towards the bottom of the valley. It then
begins to return indistinctly back, on the western side of the
round hill of Bohuntine, increasing in strength as it embraces
its southern side ; and again winds round it in a northerly di-
rection, till it bends into Glen Roy. Plate II. will show this
part of the course of shelf 4th, and Plate III. fig. 1. will fur-
nish some notion of the mode in which it crosses Glen Colla-
rig. In this last Plate, shelf 2d and shelf 3d, are seen coming
from Glen Roy through the Gap towards the eye, and termi-
nating abruptly on both sides, as a shall afterwards explain

more particularly.
The

30 ON THE PARALLEL ROADS

The lower valley of Glen Roy stretches in a N. E. direction,
from the junction of its river with the Spean, to a point at the
distance of about nine miles, where it is terminated by a rock,
having a dry craggy hollow on its north side, and a deep ra-
vine, containing the river, on the south, so that it may almost
be said to be isolated from the higher rocks flanking the glen,
between which it extends across. The country above this
point, being of a different character, may be called Upper
Glen Roy. Though not quite so narrow and confined as Glen
Gluoy, yet the green mountains of Lower Glen Roy are as
high, and rise with acclivities, which are in general fully as
steep as those of the former valley ; and throughout the great-
er part of its extent there is not much more space in the bot-
tom than is sufficient for the bed of the stream. Having wound
over the natural boundary dividing Lower from Upper Glen
Roy, and proceeding to trace the stream of the Roy upwards,
the country is found to open out into a wider and higher valley,
expanding, as it stretches eastward, the hills apparently smking
in elevation, as the level of the bottom rises. Into this the
waters of the Roy enter, by two several branches, from the
sloping hills which bound it. At a point about three or four
miles above the isolated rock, the valley becomes extremely
flat. It is skirted on the north by a low rocky ridge, which, as
it loses itself in the bottom of the plain, offers no interrup-
tion to the very gradually, nay, almost imperceptibly rising le-
vel, of the mossy ground stretching to the Loch of Spey, the
source of the river of that name. From this point, which is the
summit level, there is a gentle fall of the country, by the course
of the Spey, towards Garvamore. Returning downwards to the
head of Lower Glen Roy, we find that the river forces its way,
with great fury and precipitation, through the ravine, (marked in

the

ai

ed

OF LOCHABER. 31

the map), which surrounds the south side of the isolated rock,
and at a little distance below, it throws itself over a beautiful,
and very considerable waterfall. From this point, where the
valley widens for a little way, the river, runs through a gravel-
ly alluvial, and being soon afterwards joined by the stream
from Glen Turret, it begins gradually to display rocks in its
bed, through which, as it advances, it continues to cut deeper
and deeper, till it approaches the flat ground near the Spean.
But although the immediate course of the stream be thus held
amongst rocks, yet large beds of alluvial matter, chiefly a red *
clay, with rounded pebbles and sand, are every where to be
met with, hanging, as it were, on the sides of the inclination
of the valley, between the shelves and the river. These beds
are stratified more or less regularly, and fine sections of them
are afforded by the streams which cut through them in various
places, in their way to join the Roy, which, in its progress
down the valley, receives several tributary brooks.

I have already traced Shelf 4th around the hill of Bohun-
tine, and into the mouth of Glen Roy. It is continued up
the N. W. side:of the valley, and runs along the face of the
hill, perhaps above one hundred feet below the level of the
bottom of the Gap, (Plate III. fig. 2.). From this point it is
almost every where very. distinctly marked in its course up-:
wards, until it comes to the opening of Glen Turret, into
which it expands in a wide-extended inclined plane, above
half a mile in diameter, displaying a surface of peat-moss,
formed. over a deep alluvial deposit of gravel and sand, and
presenting a high and abrupt bank to the stream of the Roy,
running in a line with the bottom of it. The level of the
shelf seems here just to touch upon the houses of Glen Tur-

ret,

* Hence, probably, the name of Glen Hoy, or the Red valley.

32 ON THE PARALLEL ROADS

ret, situated at the upper part of this plane, near the junction
of the two streams combining to form that river, whence it
stretches under the mountain of Tom-Bhran, and crosses to
the south side of Glen Roy, narrowing as it begins to return
downwards, till it gradually again assumes the ordinary ap-
pearance of a proper shelf. I shall here content myself with
mentioning, that Shelf 4th is to be traced all the way down
the S. E. side of Glen Roy ; but I shall postpone the descrip-
tion of its progress around Glen Spean, until I shall come to
notice that valley in particular.

By looking at Plate II. Shelf 3d will be observed beginning
on the north side of the mouth of Glen Roy, at a hollow on
the S. E. side of the round hill of Bohuntine, whence it disap-
pears into the glen. As Shelf 2d does not show itself until a
little way farther on, its origin is not visible in this sketch ;
but a reference to the map will show the commencement of
both these shelves, which sweep around the eastern, or Glen
Roy side of the hill of Bohuntine, and then bend into the Gap
which leads into Glen Collarig, where they show themselves
as represented in the sketch, Plate III. fig. 2., and where they
appear to terminate suddenly. The same drawing will also
show, that they commence as abruptly on the north side, at

‘points exactly opposite to those where they are broken off on
the south side. From thence they run back towards Glen
Roy, on the same level, sweep north-eastwards into that glen,
and continue very distinctly marked throughout all their bend-
ings, in their progress upwards. Indeed there is nowhere a
more favourable view of the shelves of Glen Roy, than is en-
joyed from this Gap, (see Plate IV. which was sketched from
this point). Proceeding to trace shelf 3d and shelf 2d, up the
north-west side of Glen Roy, they are found to turn north-
wards into Glen Turret, and to run around all the sinuosities

of

OF LOCHABER. 33

of that tributary valley ; but as I mean to allot a particular and
distinct description to that glen, I shall take up these shelves
at present where they return from Glen Turret, sweeping
boldly and distinctly around the southern side of the moun-
tain of Tom-Bhran. The side of that hill which flanks Glen
Roy, being very rocky, they are to be traced, but faintly,
along its face, until they come opposite to the isolated crag
that forms the boundary of division between Lower and. Up-
per Glen Roy. Here these: two shelves, which have hitherto
kept company with one another, are now separated. Shelf 3d
being of a level considerably below that of the crag, or rather
below that of the upper parts of the bottoms of the ravines on
each side of it, and being thus prevented from’ passing
through them, and continuing onwards, at the same level
it has hitherto preserved, winds very indistinctly amongst
the hollows of the rocks, and along the rugged face of the
isolated boundary, and is then to be traced returning along
the south-western hills of Glen Roy, gaining a more mark-
ed appearance as it proceeds down that side of the valley.
But Shelf 2d, running on an elevation superior to that of
any part of the bottoms of the ravines, is of course not ob-
structed by them, but continues to run up through them into
Upper Glen Roy, whilst, at the same time, vestiges of it are
traced about the top of the independent central rock, some
parts of which seem to rise above its level. An examination
of the map, will assist.in enabling the understanding to follow
out the intricacies of this important part of the description.
Pursuing shelf 2d above the isolated crag, it is to be traced
along, near the bottom of the mountains, on the north side
of Upper Glen Roy, its level extending as far as within two
hundred yards of Loch Spey. It, however, requires consider-
able attention to follow it out in this upper valley, as in most
places it has less the appearance of a shelf than of a widened

VOL, IX. P. I. E inclined

34 ON THE PARALLEL ROADS

inclined plane, which ultimately loses itself in the flattish moss
near Loch Spey. This moss appears to be very deep ; it there-
fore seems to me to be probable, thatalthough its gradual increase
has raised the surface in this place somewhat above the level of
Shelf 2d, yet if a body of water were raised by any means to the
level of that shelf, and the stratum of moss were at the same time
to be removed, a stream would naturally flow from it towards
Garvamore, in the present course of the river Spey. The ap-
pearances of Shelf 2d, in its return down the south-east side of
Upper, towards Lower Glen Roy, are very similar to what I
have described as existing on the north-west side: it returns
into the lower glen through the ravine on the south side of the
isolated rock.

Let us now proceed to consider Glen Turret. When enter-
ed from Glen Roy, its mouth is discovered to have in the bot-
tom that large semicircular inclined plane, which has been al-
ready described as an extension of Shelf 4th. The stream of
the Turret, in its way to join the Roy, cuts through this vast
bed of sand and polished gravel to a great depth. At the cot-
tages of Glen Turret, (the site of which has been already sta-
ted to be nearly on a level with Shelf 4th), two little streams
unite to form the Turret. One of these branches comes gent-
ly from the north, through the low bottom of the glen itself,
which here rises very gradually in its level; the hills a little
way above, expanding into a considerable circle, around the
termination of the glen. The other branch pours precipitate-
ly into the lower glen, where the houses stand, from a much
more elevated valley to the north-west, marked High Glen in
the map. Proceeding to trace this stream upwards from the
houses, it is found to exhibit a continued series of cascades,
particularly at the top of this the precipitous part of its course,
where it leaves the more level bottom of the High Glen, by

falling

OF LOCHABER. j 35

falling at once fifteen or twenty feet. This, as will be seen by
reference to the map, is the very same High Glen, upon the
other extremity of which I had already occasion to touch, in
my description of Glen Gluoy, where I mentioned it as afford-
ing a vista from the head of that valley, into Glen Roy, through
Glen Turret.

The two shelves, (Shelf 3d and Shelf 2d), in winding from
Glen Roy into the south-western side of Glen Turret, are ex-
panded on a wide, and greatly elevated inclined plane, cover-
ed with peat-moss. They are consequently indistinct for a
time, and they do not become very manifest, until they cross
the stream coming from the High Glen, and lay hold of the
steeper hill. They are then particularly well defined, and are
very clearly marked in their progress all around the bendings
of the mountains of Glen Turret, till they return by its north-
west side, and sweep around the face of Tom-Bhran into Glen
Roy. But the most interesting part of their course through
Glen Turret, is that where they cross the tributary stream, as
it issues from the High Glen. In this place, Shelf 2d is found
on examination to touch exactly on the uppermost waterfall,
at an elevation about twelve feet below that of Shelf Ist, or
the Glen Gluoy Shelf. On tracing up the course of the little
stream above this waterfall, it is found to run through the bot-
tom of the High Glen, with a gentle current, without creating
any excavation, and displaying no section, though the surface
of the rock is sometimes descried in the water. It may be
about a mile from the highest cascade, upwards, in which dis-
tance it has an aggregate fall of about twelve feet. It seems
to have its origin, partly from springs on the sides of the hills,
and partly from the moisture of a flattish mossy meadow,
which continues to have an almost imperceptible rise for about
one hundred yards, till, at a point, which is not more than the
thickness of the moss higher than Shelf ist, the level of the

EQ - surface

36 ON THE PARALLEL ROADS

surface sinks suddenly into Glen Gluoy. In order to have
something like an approximation to the truth, as to what dif-
ference of level subsisted between Shelf 1st in Glen Gluoy,
and Shelf 2d in Glen Turret, I travelled from the cascade up-
wards, through the High Glen, measuring as nearly as I could
by the eye, and adding together, all the little falls of the
stream, guessing at the addition, and subsequent deduction to
be made at the end next Glen Gluoy: the result which I had
from this rude process was fourteen or fifteen feet. In order to~
make certain however, of a point which I considered most ma-
terial, I requested the favour of my friend Mr Mactean to re-
visit the ground, for the purpose of levelling it properly by
means of the instrument ; he was so kind as to indulge me, and
the twelve feet of difference of level in the height of Shelf 1st
above Shelf 2d, is given as the result of his observations.
Such, therefore, is the nature of the levels here, that suppo-
sing Glen Gluoy to be filled with a body of water to a height
equal to that of its shelf, and that, at the same time, the thick
stratum of moss were to be removed, the consequence would
be, that a stream would be discharged from it by the High
Glen, and over the cascade into Glen Turret, and so into Glen
Roy.

Let us now return to the head of Lower Glen Roy, where
Shelf 3d and Shelf 2d, having wound from the ravine on the
south side of the isolated rock, run faintly down the faces of
the mountains on the south-west side of the glen, gaining
greater distinctness of form as they proceed. They become
particularly well defined, just at f in the map, where they sub-
tend the mouth of Glen Turret ; and in that part of the south
side of the valley, there are appearances which may be worth
notice. At first sight, one might be led to imagine, that there
are no fewer than seven different stages of shelves here. A
sketch could have given no idea of these; but the diagram,

(Plate VII.

OF LOCHABER. 37

(Plate VII. fig. 6.), may be of some use in helping the descrip-
tion of them. In it, the three uppermost lines represent the
proper horizontal shelves 2d, 3d, and 4th, whilst all the others
below have an inclination downwards in the direction of the
fall of the glen, and this inclination, increases in each succes-
sive shelf, in proportion to its greater proximity to the river.
- These inclined lines of shelves can hardly be said to be on the
side of the hill, but have rather the appearance of a series of
small flats, one below another, between the hill and the river.

- Shelf 2d and Shelf 3d, are to be traced, as well as Shelf 4th,
with very little interruption along the faces of the mountains
running down the south-east side of Glen Roy. Opposite to
the hill of Bohuntine, the glen makes a great bend to the
south, and afterwards returns to its south-east direction. It is
near to this point that the mountains on the south-east side of
the valley, though they still keep their roots so advanced as to
leave the glen perfectly narrow in the bottom, yet retreat
backwards above, surrounding and embracing a high and very
extensive semicircular plane, apparently ‘covered with a peat-
moss; but soon afterwards they again advance in some degree,
and at Jast finally terminate in the rocky prominent hill of
Craig-dhu, which forms the more elevated part of the division
between the mouths of Glen Roy and Glen Spean. Shelf 2d
and Shelf 3d, being both of elevation superior to that of the
bottom of the high plane, naturally bend away from Glen Roy,
in a manner somewhat similar to that in which they run into
the Gap of Glen Collarig, and winding around the amphi-
theatre of hills, and returning with them again, all traces of
Shelf 2d are suddenly lost, nearly opposite to the point where
it begins on the south-east side of the hill of Bohuntine.
Shelf 3d runs on a little farther, to the rocky angle of Craig-
dhu, where it likewise is abruptly terminated, also opposite to

the

38 ON THE PARALLEL ROADS

the spot where it is first observed on the hill of Bohuntine.
Neither of these shelves are ever met with afterwards, in any
glen below these points of termination. Shelf 4th, which is at
an elevation below that of the high semicircular plane just men-
tioned, does not bend into it like the other two ; but the hills
nearest the river beginning now to sink in height, it continues
to run in a more direct sweep towards the foot of Craig-dhu.
From the base of this more retired, and more elevated hill, an
apparently mossy, and considerably inclined plane, stretches
for half a mile in a south-west direction, towards the point of
junction of the rivers Roy and Spean. But just above the
spot where these streams unite, this plane again rises into the
circular and isolated rock called Mealderry, which is particu-
larly laid down in the map, and which may be easily reeogni-
zed in Plate II. as being near the eye, and just beyond the
mouth of the valley of Glen Spean. Shelf 4th, as it sweeps
from Glen Roy around the base of Craig-dhu into Glen Spean,
applies exactly in level to the upper line of the inclined mossy
plane, lying between Craig-dhu and Mealderry; and the top
of the isolated rock of Mealderry, rising somewhat above this
level, is surrounded by a partial delineation, of what the level-
ling instrument proves to be an independent portion of the same
shelf.

Although Craig-dhu, which may be properly considered as
the mountain dividing Glens Roy and Spean from one another,
thus appears to retreat backwards above, from the actual point
where the rivers meet, yet the entrance of Glen Spean is very
much confined, by the advance of the lower rock of Mealder-
ry, on the north side of the valley, towards the base of the
mountain on the south side. These come bending from Ao-
nachmore, a mountain of the Ben Nevis groupe, and making a
wast sweep around the great hollow basin, in the country be-

low

OF LOCHABER. 39

low the junction of the Roy and Spean, push their roots into
the very bed of the latter river, just above the House of Inch.
From hence they run westward up the glen, forming its south
side, with a straight and highly inclined face. The side of
the mountain Craig-dhu, constituting the north wall of Glen
Spean, has a front as even and as steep, as that of those oppo-
site to it. Just above the narrow entrance of the glen, the
hills on each side of the valley are about half a mile asunder ;
but some miles farther up, they begin to recede greatly from:
one another, and they seem to sink in their elevation as the
bottom of the valley rises. The whole length of Glen Spean,
from Inch to the Pass of Muckul, is about twenty miles. This
pass, affording an opening between Glean Spean and the Val-
ley of the Spey, +5 the summit level between them. Although
it is not productive of any streams, it disparts the waters that
run to the eastern and western seas; and yet the highest part
of its bottom, is only elevated a few feet above the present le-
vel of Loch Laggan. By a reference to the map, it will be
seen, that the river Pattaig, after issuing from its loch, has a
directly north-east direction, as if it were about to run towards
the river Spey, which is certainly its most natural course ; but
just before coming upon the bottom of the Pass of Muckul, it
meets with the rock laid down in the map, which compels it to
make a sudden and capricious bend to the west, at a very acute
angle to its former line, and after a slow run of somewhat
more than two miles, a considerable part of which is na-
vigable by a boat, it empties itself into the upper end of
Loch Laggan. This lake is eight or nine miles in length
On the north side, the mountains are partly of gentle acclivi-
ty, but in some places, they rise almost perpendicularly to a
very considerable height. Although those on the south side
are of inconsiderable elevation, yet they are bold and rocky to

the

40 ON THE PARALLEL ROADS

the water’s edge; and, indeed, the whole shores of the lake
may be in general called rocky. There is a good deal of wood
upon both shores. The river Spean, which issues from the
western extremity of Loch Laggan, runs slowly and smoothly
for about two miles, cutting its course through flats of deep
alluvial earth and clay, and rarely exhibiting any rock. The
Spean, in its progress downwards, receives the Gulbean water,
which enters it from the south; and, at about four or five miles
above the House of Inch, it is joined by the river Treig, which
has a run of nearly two miles from its lake lying to the south,
the valley of the Spean being here of very considerable
breadth.

The opening into the north end of Loch Treig is very ro-
mantic, being reduced to a narrow but grand pass, by the ad-
vance of the mountains on each side, which present two lofty
and rocky fronts, guarding its entrance, (see Plate VI.), from
which the. lake expands, as it extends in a direction a little to
the west of south. The shores of Loch Treig are in general
bold and rocky, having their woods of birch-trees scattered
over them. Immediately opposite to, and to the north of the
narrow outlet of Loch Treig, there is a very singular, round,
isolated little hill, with a flattish rocky summit. This is laid
down in the map, and is called Tom-na-Fersit. After leaving
the lake, the river Treig, winding amongst hillocks, rushes vio-
lently over the rocks which it exposes in its progress, and as
it approaches the point of junction with the river Spean, its
bed becomes deepened into a ravine, and it is projected over
several falls,

Proceeding to trace the river Spean downwards, after its
union with the river Treig, its course will be found extremely
interesting ; for it is not only bounded, on the great scale, by
the mountains forming the proper walls of the glen, at some

distance,

OF LOCHABER, 41

distance, but it has also, much nearer to its bed, a second and
interior bounding enclosure, consisting of a line of banks on
each side, flattish, and rather plain above, but having steep
and abrupt, though perfectly smooth faces, towards the level
bottom in which the river runs. These banks seem to be
chiefly formed of alluvial matters. They appear immediately
_ below the junction of the river Treig, whence they sweep with
various bendings, sometimes at a greater, and sometimes at a
lesser distance from the Spean, enclosing a beautiful narrow plain
about a mile in length, through which the stream flows gently
over a gravelly bottom, This plain is suddenly shut in at
the lower end, by the close approach of these banks on both
sides. Here the river, suddenly altering its character, pours
itself into a deep rayine, which jt seems to have worn through
a rocky neck of about fiye hundred yards in thickness, where
‘jt is heard roaring along in a series of cataracts, of which the
great waterfall of Tulloch forms the grandest specimen. The
stream has no sooner effected this turbulent passage, than it
enters a second beautiful and level plain, about two miles
Jong, and bounded on the sides by a similar series of banks.
Through this it again flows with perfect placidity, until, by a
~ second approach of the sides to one another, at a point a little
above what I have called the Mouth of Glen Spean, the tran-
quillity of the river is a second time interrupted by another
rocky neck, like that I have just described. Here it again
forms into an abyss, of the same depth and appearance as the
former, where, besides being hurried over a number of lesser
cascades, it is precipitated over the fall of Munessie, equal in
grandeur to that of Tulloch. These two necks of rock, through
which the Spean has thus cut its way, are both called in Gae-
lic Kenmuir, which signifies, the End of the Lake. Escaping
from the gloomy and overhanging rocks of this second deep

VOL. IX. P. L F and

42 ON THE PARALLEL ROADS

and narrow ravine, the river again puts on the peaceful charac-
ter, and flows in a broad channel ‘through the Meadows of
Inch. After its union with the Roy, it proceeds, (as I have
already noticed), across a hollow and shelving basin in the
open country, somewhat more than two miles in extent, till
the banks again approaching, and closing in on the river, ita
third time, and on a still more magnificent scale, exhibits the
deep ravine, and the waterfalls and rapids, which so often ar-
rest the attention of the traveller who crosses it at High-
bridge. The shores of these three successive minor valleys,
which may be said to be included in the larger, are what I have
numbered 5, 6, and 7 in the map.

I must now, again, take up the consideration of the course
of Shelf 4th, which having wound from Glen Roy around the
base of the hill of Crag-dhu, stretches very distinctly up the
smooth and even faces of the mountains on the north side of
Glen Spean, the bottom of the valley rising towards it as it
proceeds, until at last it approaches so near to it in eleva-
tion, that the Engineer of the Parliamentary Commissioners
has actually availed himself of the line of shelf, to construct
on it a part of the great new Loch Laggan Road. As the shelf
approaches within two miles of Loch Laggan, it begins to be |
identified with the upper bounding line of the flats of deep al-
luvial earth and clay, through which the river Spean flows
from the lake. It is then to be traced all up the north shore
of Loch Laggan, being only a few feet above the level of its
water, and in most places only a few yards from its margin ;
and running along the banks of the river Pattaig for about two
miles, it crosses that river at Muckul, on a level equal to that
of the summit-level of the bottom of that pass, and in such a
manner, that it is evident, if a body of water were raised to the
level of the shelf, a stream would run from it, through the Pass of

Muckul,

OF LOCHABER. 43

Muckul, towards the river Spey. Returning down the south
bank of the Pattaig, Shelf 4th is to be traced all around the
south side of Loch Laggan ; and it exhibits nearly the same
appearances on the south side of the river Spean, that I have
already described it to do on the north side. As it approaches
the river Treig, it sweeps round in the direction of the mouth
of the glen and lake of that name, where, notwithstanding the
rocky nature of the mountains, it is found to be very deeply
marked. It enters the jaws of the pass into Loch Treig in the
manner represented in Plate VI.

By far the most satisfactory and perfect example, of any
shelf completely surrounding the top of a hill, is to be obser-
ved.on the isolated one of Tom-na-Fersit, immediately oppo-
site to the opening into Loch Treig. Shelf 4th is most dis-
tinctly and broadly traced around it, at the same level that it
appears on the rocks, where it enters to Loch Treig. And
what is still more worthy of remark, the little hill, having a se-
cond and inferior rocky top, rising above the level of the shelf,
it is perfectly surrounded also, and detached from the princi-
pal summit, so as to give this portion of shelf, which belongs
independently to Tom-na-F ersit, the appearance laid down in
the map, or to shew it on a larger scale, something like this :

‘A and B being the two tops of the hill rising out of the sur-
rounding shelf. The rocks on the interior angle of the shelf,
are here particularly rounded, and have all the characters of
those bounding the edge of low and rocky islands, frequently
met with in Highland lakes. Where the smaller top is divid-
; r2 ed.

44 ON THE PARALLEL ROADS

ed from the larger, a peat-moss has been formed, though the
comparatively trifling surface exhibited by the whole of the
elevated and rather rounded top of this isolated hill, is cer-
tainly a situation where such a deposit is hardly to be looked
for.

The numerous torrents that pour down the sides of the
mountains of Loch Treig, have very much defaced the course
of Shelf 4th around that lake. Although very distinctly seen
at its northern end, it is but faintly traced along its eastern
side. It is to be observed at the southern extremity, and ap-
pears very visible on the western side, where it leads back and
winds again into Glen Spean.

After leaving the mouth of Loch Treig, Shelf 4th is easily
traced along the hills on the southern side of Glen Spean. It
appears particularly well marked on the even faces of the
mountains, for a long way before it comes to what may be
called the Mouth of the glen; and just above the House of
Inch, it sweeps away in company with the receding moun-
tains, where, though faint, it is easily followed, to a ravine
called Corr-a-cloichlich, whence I thought I could even trace
it, though with some little difficulty, through an opening in a
thin birch wood, on the side of Aonach-more, nearly as far as
the projection of that mountain, where all appearances of it
are finally lost. The projection to which I allude here, is the
same which, as I formerly remarked, is met by a semicircular
range of little eminences, forming a kind of elevated moor,
sweeping towards it from Highbridge, and enclosing what I
have called the Basin, in the open country of the Spean. This
moor rises nearly to the level of Shelf 4th, and some of its
more elevated points seem even to rise above it. These last.
observations will be found to be extremely important in the
theory which it is now my intention to propose.

PARTICULAR

OF LOCHABER. 45

Particular Theory of the Causes which may be supposed to have
operated in producing the Shelves in the Glens of Lochaber.

ALTHOUGH it appears to me, that no one can examine even
a portion of these shelves with attention, without ascribing
them to an aqueous origin, and without being likewise perfect-
ly satisfied, that they were formed by the level waters of lakes,
yet I have been taught by experience, that it is impossible to
go farther in speculation, without a thorough knowledge of all
the glens, as well as of every part of the tortuous course of
the linear appearances to be found in them. Almost every step
I took in this interesting investigation, seemed to lead to some
new conclusion, as to what was the probable topography of the
ancient lakes; and it was not until I had collected all those
facts which I have stated in the foregoing pages, in what I
fear will be considered as rather tedious detail, that any thing
resembling a satisfactory theory of their distribution, shape,
extent, and final evacuation, suggested itselfto me. This I now.
venture to lay before the Society, trusting to its indulgence:

It appears that Glen Gluoy. possesses Shelf Ist, which is the:
highest of all; and that it is to be found in no other glen:
From this I would infer, that Glen Gluoy was at’ one period
an independent lake, having a level higher than any of the
others in’ its vicinity. The next two shelves in elevation,
which are Shelf 2d and Shelf 3d, are confined entirely to Glen
Roy, and its smaller tributary glens; and are found to run
down and terminate, nearly together, in the Gap of Glen Col-
Jarig, on the north side, and in the mouth of Glen Roy on the
south side of the round hill of Bohuntine, as’ represented in

the

46 ON THE PARALLEL ROADS

the map, or perhaps more satisfactorily in the following dia-
gram, in which Shelves 2d and 3d alone are marked,

and where A is the Gap of Glen Collarig, B the hill of Bo-
huntine, C the mouth of Glen Roy, and D the angle of the
mountain Crag-dhu. From these facts it would seem, that
Glen Roy must have been for some time an independent lake
also, having its south-west extremity situated somewhere near
the hill of Bohuntine, where it must have terminated in two
bays, one on each side of that round hill. And as we see that
there are two shelves of different elevations, which are the pro-
perty of Glen Roy alone, it is equally evident, that its lake must
have once existed for a time at the level of Shelf 2d, and must
have afterwards subsided to that of Shelf 3d. But we find that
Shelf 4th is common to both Glen Roy and Glen Spean ; con-
sequently this implies a second subsidence of the Glen Roy
lake, reducing it to the same level, and making it a portion of
a lake which must have pre-existed in Glen Spean. In the
primary state of things therefore, we find an independent lake
in Glen Gluoy, which may be called Loch Gloy ; another in
Glen Roy, at a level about twelve feet below that of Loch
Gluoy, which may be called Loch Roy; and a third, covering

the

OF LOCHABER. 47

the whole of Glen Spean, Loch Laggan, and Loch Treig, at a
level about two hundred and eighty feet below that of the pri-
mary state of Loch Roy, to which the name of Loch Spean may
be given. As each of the different shelves may be traced
around and across, at some point lying towards what is now
the upper extremities of these valleys, whilst they appear in
every instance to be suddenly broken off, at what is at present
their ower ends, or mouths ; it follows, that if there ever were
any barriers, to keep these several lakes up to their level, they
must have existed somewhere about what are now the lower
ends of the present valleys——Having made these general re-
marks, it will now be proper to consider, what were the boun-
daries and outlets of these respective lakes ; and, in doing this,
we shall begin with Loch Gloy.

The shelf which appears to indicate the former existence of
this lake, is found on the north-west side, some little way
above the present entrance of the glen. This entitles us to
suppose, that the lake at least occupied the extent of the glen,
~ from this point upwards, as far as the present head of it, where
the shelf-is seen to sweep round, in order to return. But I
trust it has already appeared to be evident, from the descrip-
tion I have given, that when the water in Glen Gluoy was fill-
ed up to what is its present line of shelf, it must have
run by a natural channel towards Glen Turret, by what
I have denominated the High Glen, (for which see the
map). To produce this effect, however, an immense bul-
wark or barrier would be required, at what is now the
mouth of Glen Gluoy, which would in that case become
the head of the lake. Let us, in the meanwhile, take it
for granted, that some such bulwark did exist, at, or near
to Lowbridge, and then it would follow, that what is now
the upper end of the Glen, must have been then the low-
er end of the Loch Gluoy, from whence the river Gluoy

would

48 ON THE PARALLEL ROADS

would naturally issue, and whence it would run by a gentle
course through the High Glen, into that bay of Loch Roy
which is now Glen Turret, and which, in this view of the mat-
ter, we must call the Bay of Turret.

Let us now consider what was the state of Loch Roy when
at its highest-level. A glance at the map will show, that the
south-eastern extremity of its present glen, must have been
shut in by two barriers, or rather two portions of one great
barrier, of which the round hill of Bohuntine formed the central
part, and of which also Mealderry might, or might not, have
constituted a fragment. This barrier then, must have run in
a semicircular manner, from the projecting angle of Crag-dhu
on the east, towards the south-eastern side of the roundish hill
of Bohuntine; and must again have extended itself from the
western side of that hill, across Glen Collarig, so as to be joined
to the faces of the mountains in the northern angle of that
little valley, and having the Gap on its eastern, and Glen Col-
larig on its western side. The supposition, with regard to this
barrier, is founded on the consideration, that it could not have
been higher up the glen, since it must have been lower down
than the points, where the shelves indicating the existence of
the independent Loch Roy are abruptly broken off; and it is
not so probable, that it could have been much lower down
than this, since neither Shelf 2d nor Shelf 3d, are ever again
met with, after they disappear thus suddenly. Moreover, we
cannot go farther to the south-westward, without interfering
with what must have been Loch Spean,—and then, from the
inspection of the ground itself, this appears to be by far the
most natural and probable position for such a barrier, of which
the very shape of the rounded hill of Bohuntine, seems to tes-
tisfy, that it formed a part. But at the tim ewhen this barrier

existed, this southern end of Loch Roy must have been
its

OF LOCHABER 49

its upper extremity, from whence the surface of the lake
extended all the way to the mossy ground within a few yards
of Loch Spey, where we have seen that Shelf 2d is identified
with the flat, in such a manner, as in my opinion to warrant
the conclusion, that the primary Loch Roy discharged its
own waters, and those it received from the tributary Loch
Gluoy, down through the hollow of the present course of the _
river Spey, by Garvamore, to the German or Eastern Sea.
In this state of matters, the boundary rock between upper and
lower Glen Roy, some portions of the top of which seem to
rise a little above the level of Shelf 2d, and around which
there is a partial delineation of it, was probably a very low,
rocky, and perhaps broken island ; and what is now Glen Tur-
ret, must have been a large bay, having two smaller ones in-
cluded in its interior. The Gap,—the mouth of Glen Roy,—
and the high plane to the north of the projection of Craig-
dhu, must then also have formed three considerable bays.

I shall now leave Loch Roy in its primitive state, in order
to take a view of the boundaries and barriers of that of Loch
Spean. In doing this, I must entreat attention to the state of
appearances in that part of the mutual valley of the Roy and
Spean united, which crosses in a semicircular line, from the
south-western corner of Ben-y-vaan on the one hand, to the
northern projecting point of Aonach-more on the other.
From the same species of reasoning which I employed to esta-
blish the barrier of Loch Roy, it appears evident, that the bar-
rier of Loch Spean, could not have existed above the semi-
circular line I have just described, since the two abrupt
ends of Shelf 4th, indicating the former existence of Loch
Spean, come, if not quite up to the two extreme points of it,
at least to within a very short distance of them ; nor is it to
be supposed, that this barrier could have been much to the

VOL, IX. Ps L. G south-west

50 ON THE PARALLEL ROADS

south-west of these points, since not the slightest vestige of
Shelf 4th, has been discovered any where in that direction.
But as, in the case of Loch Roy, this also actually appears on an
examination of the ground, to be by far the most natural and
probable position for the barrier of Loch Spean, since the se-
micircular range of little hills, or what I have called the eleva-
ted moor, which exactly follows the supposed semicircular
line I have sketched out, rises even now, nearly, and I believe
in some places entirely, to the level of Shelf 4th, so that if the
ravine at Highbridge were closed up, and the deficiencies in the
elevated moor supplied, the perfect barrier for the confine-
ment of the water of Loch Spean, would be reproduced. I
say the perfect barrier,—because I believe that the lake had
no outlet here at all, but that this was its upper end, and that
as in the other cases, the former loch and the present valley
have changed extremities. The primary Loch Spean, then,
must have stretched from a point a little above Highbridge,
all the way to the summit-level of the bottom of the Pass of
Muckul, a distance of not less than twenty-four miles. There
the level of Shelf 4th sufficiently shows, that the surface of the
lake had such a relation to the ground at that end of it, that
it must have discharged the River Spean (or Little Spey,
for such is the interpretation of its name), through the Pass
of Muckul, by a straight and natural course, carrying’ it
to direct union with the Spey, which at that time brought
along with it the Gluoy and the Roy, in addition to the
waters supplied by its present source. Whilst matters were
in this situation, the river Pattaig must have entered near
the eastern end of the lake, to be immediately afterwards dis-
charged by it through the Pass, along with the rest of the wa-
ter passing from Loch Spean, and in a course much more na-
tural to it than that in which it now runs. Loch Treig must
then have been a great southern limb of Loch Spean, and the

tops

OF LOCHABER. Sl

tops of the little hill of Tom-na-Fersit must have formed two
small islands; and it would depend upon the circumstance,
whether Mealderry was, or was not, a portion of the Loch
Roy barrier, (which, by the bye, I am rather inclined to think
it was not,) whether its top was also an island in the primary
or independent state of Loch Spean, or whether it only be-
came so afterwards. A reference to Plate VIII. fig. 1. will
explain what I suppose to have been the primitive state of
Lochs Gluoy, Roy, and Spean. I conceive that Loch Gluoy
always remained an independent lake up to the period of its
final evacuation: but it is evident, that some intermediate
changes took place as to the circumstances of the other two
lakes ; and these will now fall to be considered.

I believe it will be readily admitted, that it is much easier
to suppose the existence of former barriers, than to discover
the means which operated in their removal ; but it must be al-
so granted, that the difficulty of accounting for the destruction
of such large masses, does not by any means imply that they
never had any being at all, particularly where a number of
facts remain to lead us to an opposite conclusion. From all
the present appearances, it is extremely probable, that the bar-
rier of Loch Roy, was not only very thin, but of soft materials,
at the two parts which have been removed. When we consi-
der in addition to these circumstances, that the level of Loch
Roy was about two hundred and eighty feet above that of
Loch Spean, and that, consequently, the pressure against this
weak barrier must have been very great, it will not ap-
pear by any means very improbable, that some partial rup-
ture may have taken place at one, or perhaps both of the nar-
row necks A and B, Plate VIII fig. 1., so as suddenly to re-
duce the level of Loch Roy to Shelf 3d, where it continued to
remain for some time. It is proper to remark here, what I

«2 trust

52 ON THE PARALLEL ROADS

trust will appear sufficiently evident, if the explanatory dia-
gram I have employed, Plate VIL. fig. 5. be examined, that
the operation of the waves of a lake, in eating out a shelf on
the side of a mountain, will be much more powerful when the
surface of the mountain is yet entire, than it will continue to
be afterwards, when a certain proportion of sloping beach has
been formed, over which it may in some degree waste the fu-
ry of its waves. We see that the natural shelves now existing
around the borders of our Highland lakes, do not appear to
have been very much, if at all increased, beyond the breadth:
of those remaining from the lakes which we suppose to have
been emptied at so very remote a period. The depth, there-
fore, of the indentation of a shelf, does not form any criterion
whereby we may judge of the length of time expended in its
formation. Shelf 4th furnishes an excellent example of this
observation, for it is as deeply indented, and as well defined,
in many parts of Glen Roy, as it is any where in Glean Spean,
although it is evident, that the lake which formed it, must
have existed much longer in the latter glen than it did in the
former. It does not therefore appear to be absolutely neces-
sary, that Loch Roy should have remained long at the level of
Shelf 3d, before its second subsidence took place ; but it is not
very material to the theory whether it did so or not. It is
evident, that one material change must have taken place in it,
in consequence of the sudden fall of its level. The whole ex-
tent of Upper Glen Roy must have been laid dry, and, conse-
quently, it would now no longer discharge the united streams
of the Gluoy and Roy, by the channel of the river running
from the point at Loch Spey ; but leaving the stream from that
little residuary lake to pursue its own course, it would now, in
the first instance, become tributary to the great Loch Spean,
and would be carried by means of its river through the Pass of

Muckul,

OF LOCHABER. 53

Muckul, to join the lower part of its former run. This se-
condary state of matters is represented in Plate VIII. fig. 2.
Although it is not very easy to conceive what might be the ex-
act effect of this change, in the course of so very considerable
a body of running water, yet there can be no doubt that its
power would in time be felt, directed, as it now came to be,
against a thin barrier, composed of soft materials, and already so
much weakened, as it must have been, by so great a rush of
water, as that which pressed over it during the sinking of Loch
Roy from the level of Shelf 2d to that of Shelf 3d. Indeed the
very circumstance of admitting the possibility of such a breach
having ever taken place once, implies that the causes for its hap-
pening a second time must have been greatly multiplied ;_ nor
can any one hesitate in believing, that if the destruction once
began, it would likewise be now proportionably much more
sudden and tremendous. Be it remembered, too, that although
the perpendicular height to be swept away, was greater upon
this second occasion than it was in the first instance, yet it
was not necessarily very great,—not certainly of necessity
more than about two hundred feet, the difference of elevation
between Shelf 3d and Shelf 4th. We see, indeed, by the ap-
pearances remaining in Glen Collarig, where there has been
little or no change since that rupture, which, during the second
subsidence of Loch Roy, let off a portion of its waters there,
that the opening which took place in the barrier between the
Gap and it, did not extend to half that depth, otherwise the uni-
ted Lake of Roy and Spean would have gone entirely through
there, and would have made an island of the hill of Bohun-
tine. But where the Roy now flows on the eastern side of
that hill, the depth of barrier destroyed must have been at
least equivalent to that of the depth of Shelf 4th below the le-
vel of Shelf 3d. But as I shall afterwards exhibit causes for

the

54 ON THE PARALLEL ROADS

the subsequent deepening of the present mouths of the glens,
by means of their rivers alone, it is unnecessary to suppose at
present, that the barrier was destroyed by the second subsi-
dence of Loch Roy, to a depth much under that which was
merely necessary to reduce Loch Roy to the level of Loch
Spean, of which it now became an immense arm, as represent-
ed in Plate VIII. fig. 3.

The consideration of what I suppose to have been the grand
cause which operated in producing the sudden and contempo-
raneous evacuation of the independent Loch Gluoy, and the
great, and by this time united Loch Spean and Roy, again
leads me to the Glen-mor-na-Albin, or Great Glen of Scot-
land. To those who have travelled throughout the extent of
this remarkable valley, it seems to me hardly necessary to’
point out the various circumstances that lead to the supposi-
tion of its being an immense rent across the island, produced by
some extraordinary and powerful convulsion. Indeed the whole
of its appearance is more strikingly convincing to the eye when
examined, than any detailed description can be to the mind,
however minutely conveyed in words. But if we consider the
vast depth of its lakes,—the almost rectilineal straightness of
its direction,—its uniform narrowness,—the uniformity also
of the general shape of the abrupt and ' lofty fronts of its
bounding mountains,—the seeming adaptation of those on op-
posite sides to each other,—the wonderful equality of its level
from one sea to the other,—and the lowness of its summit-le-
vel,—which, as it is composed of vast beds of alluvial matters,
must have been even raised by time greatly above its original
state,—if all these circumstances, I say, be considered, it will at
least appear possible, that it may have owed its origin to some
such unusual event. But as I believe the evacuation of the lakes
to have been owing to no less magnificent a cause than this, I

am

OF LOCHABER. 55

am also inclined to think, that the evidence which they have
left behind them, will reflect some strong rays of probability
upon the theory I have adopted as to the formation of this
very singular glen; and that the Shelves of Lochaber, and the
Glen-mor-na-Albin, will be found upon examination, mutual-
ly to elucidate the history of each other.

Let us suppose, then, that the lochs were brought to the |
state which is represented in Plate VIII. fig. 3., and that the
Glen-mor-na-Albin having as yet no existence, the whole
country to the north and west of what was then their upper
extremities, was a solid and undivided mass. An examina-
tion of the map of Scotland would at once show, that in such
a situation of things, the discharge of the combined waters,
generated in all of them, towards the Eastern Sea, by the chan-
nel of the River Spey, would have been then much more na-
tural, than it even is now to the Western Sea by their present
courses, under the circumstances that exist. Nor can it be
doubted that the opening of this vast fissure, would produce
all the effects necessary to explain the seeming difficulties, and
to reconcile the various incongruities that otherwise encoun-
ter us, and perplex our speculations on this interesting subject.
The terrible convulsions attending the creation of such a
yawning crack, running through ground previously unbroken,
although it might not cut exactly across in the very line be-
tween the lakes and their south-western boundaries, so as to
allow the whole body of the water to escape from each of
them in one moment, would certainly so rive and shatter the
country, that the weight of the water itself would almost in-
stantly complete the annihilation of any thing that remained
to prevent its escape: From the appearances which still ex-
ist indeed, this would seem to have been the very manner in
which it must have operated with respect to the Spean lake,

since

56 ON THE PARALLEL ROADS

since we see that the middle of the crack, runs nearly in the
line of the river Lochy, whilst the western termination of the
supposed Loch Spean must have been above Highbridge. It
is therefore probable, that the small hills that are scattered
like an elevated moor, in a semicircular form, from Ben-y-
vaan, by Highbridge, to the projection of Aonach-more, are
the remains of the shattered barrier, towards the destruction
of which the discharge of the lake added the immediate assist-
ance of a tremendous rush of water. The appearances at the
Mouth of Glen Gluoy, and particularly the manner in which
the shelf of that glen suddenly stops, on the south-east side,
whilst it comes farther down on the north-west side of the
valley, would rather seem to indicate, that a smaller crack,
(of which there would naturally be several,) branching off from
the great rent, had taken a zigzag direction, somewhat in the
bent line formed by the mouth of Glen Gluoy and the Glen of
Fintack ; and indeed the whole appearance of this tributary
glen would induce one to espouse such a supposition. —

If it be at all admitted, that these lakes ever had existence,
which I presume to suppose can hardly be doubted, I have
already shown, that the whole water discharged from them,
must have run towards the Eastern Sea. If this was the case,
it appears to me to be impossible to account for the disappear-
ance of the terra firma which shut in their western or upper
extremities, in any other way than by the means I have sug-
gested ;—means which were fully adequate to produce at once
the discharge of the united Loch Spean and Roy, and of the
independent Loch Gluoy. It even appears to me to be not
unlikely, (though I do not consider the aid of such a supposi-
tion to be absolutely necessary to my theory), that in a coun-
try where such a great convulsion was to happen, some previ-
ous throes might have manifested themselves, which might have

even

OF LOCHABER. 57

even had some share in weakening the barrier dividing Loch
Roy from Loch Spean.

The present depth of the Glen-mor-na-Albin, is more than
enough to have accounted for the escape of the waters of these
glens towards either sea; it is, however, evident, that it has
been once much deeper, since the Caledonian Canal is now
cutting through great beds of alluvial, to which the debris of
the mountains brought down by torrents are every day add-
ing, so much so indeed, as to produce an evident diminution
in the extent of the higher lakes. “And then Loch Ness itself
is so very deep oe ahet ak I am rather disposed to think, that
the abyss containing it, may have been produced by some of
the last pangs of the convulsion, which perhaps operated with
greater violence there than elsewhere. A belief is very preva-
lent, that Scotland, to the northward of this glen, was once in-
sulated from the rest of the kingdom, by a narrow strait of the
sea running through it ; but from the circumstance of the ear-
ly disappearance of all marine exvviz, in the course of the cut
of the canal, from the sea, through the flat ground near Inver-
ness, this notion appears rather improbable. It would, how-
ever, be a highly interesting experiment, to bore for nearly
a hundred perpendicular feet, at some point about the sum-
mit-level of the Canal, in order to discover, what substances
would offer themselves. Some very curious geological specula-
tions might be awakened by such a trial, and some additional
and unexpected light might thus be thrown, upon the theory of
the ancient Lochaber lakes. It is very likely, that much evi-
dence bearing upon this last subject, might also be gleaned, by
extending our inquiries to the two extremities of the Glen-
mor-na-Albin, as well as to the appearances at the mouth of the
river Spey. The few investigations I have made as to these
points, have been much more superficial than I could have

VOL. IX. P. I, H wished,

58 ON THE PARALLEL ROADS

wished, nor can I pretend to found much upon them. The
western end of the Great Glen of Scotland, is flanked by such:
rocky mountains, as to render it impossible to conceive that
the portion of water which escaped that way, however great
might have been its body, or however violent its discharge,
could have produced much effect, so as to leave traces of its
action ; and the sea also, on this side of the island, being so
much nearer the immediate scene of the catastrophe, would
naturally counterbalance the violence of the flood, by the sud-
den influx of its waters. Accordingly, I was not conscious of
observing any thing on the west coast, that could lead to any
conclusion, favourable to the theory I have ventured to ha-
zard. But, upon the east coast, I thought I discovered ap-
pearances that seemed in a very material degree to illustrate
and strengthen the views I entertain. In the neighbourhood
of Inverness, there are great hills of rounded gravel, and sand,
in what may be called the Mouth of the eastern end of the
Glen-mor-na-Albin. The Hill of Tom-na-hiurich, near the
Town of Inverness, in particular, is extraordinary both for its
structure, its shape, and its situation; being found standing
nearly in the middle of the alluvial flat, like the inverted hull
of a ship in form, and presenting the end of its long diame-
ter towards the Great Glen, in such a way, and being so sha-
ven off on the two sides, as to leave little room for doubt, that
it stands as a living witness of that terrrible flood of water,
which resulted from the sudden opening of the Glen-mor-na-
Albin.

It remains for me now, to endeavour to trace out the
changes which have taken place in the glens left by the lakes,
and which may be considered as the secondary effects of the.
grand catastrophe ;—and, first, as to those in Glen Gluoy. The
chief streams of this glen are three,—one running from Glen

Fintack, and the other two coming from the hills on the north
and

OF LOCHABER. 59

and south sides of its present upper extremity. Whilst Loch
Gluoy existed, the water of these streams was all discharged
by the High Glen, into Glen Turret. But no sooner was the
lake broken up at its other extremity, than the water would
cease to flow in that direction, and would instantly rush into
that which it follows at present. An attention to the south-
ern branch of the river, at the head of Glen Gluoy, (to which,
in the map, as well as in my description, I have given the
name of the River Gluoy), as well.as a remembrance of its va-
rious accompaniments in that quarter, will afford matter for
some curious remark. It is discovered to descend from the
hill, by a fall, upon that broad part of the shelf which must
have been formerly a gently shelving bay of the ancient lake ;
where, whilst the water existed, its force would be immediate-
ly broken, and the stream would then have no effect in cut-
ting, but would rather add to the shoal, by the deposition of
the debris brought down with it from the mountain. But no
sooner was the lake evacuated, than all check to the full exer-
tion of the force of its descent would bé removed, its powers
of excavation would be brought into perfect: action; and the
violence of its descent would soon cut open the deep ravine
which I have described, and marked in the map, as dividing
the shelf across its whole breadth ; and its power would conti-
nue undiminished, as long as any material difference existed,
between the degree of declivity of the bottom of the ravine,
and that of the lower part of the glen into which it issues. I
therefore conceive, that this part of Glen Gluoy is particular-
ly interesting, because it displays in a most satisfactory man-
ner the mode in which running-water always operates, in
bringing its course to a regular equality of fall, throughout all
its parts. The present depth of Glen Gluoy, at its lower end,
cut as it is also into a deep ravine, furnishes no proof that the

H 2 origina]

60 ON THE PARALLEL ROADS

original lake was nearly so profound in that quarter. The
sudden burst of the water must have done much to scoop it
out almost instantaneously, and the river itself would continue
active in reducing it, in a proportion exactly equal to the
quantum of its deviation from a regular declivity, counterba-
lanced as it might be, by the various degrees of hardness of
the materials through which it had to work. These last ob-
servations apply equally to the effects which must have been
produced by the rivers of all the glens, after the evacuation of
their lakes. We see how the rocks have been cut in the de-
scent of the stream from the High Glen, which must have
been done in the same manner I have just described, after
the water escaped from the Bay of Turret. So, after the
subsidence of Loch Roy, which laid dry all Upper Glen
Roy, the stream would, in the same way, begin to cut the
ravine, to the south of the rock, dividing Upper and Un-
der Glen Roy; and the operations there, would be increa-
sed by the farther reduction of Loch Roy, to the level of Loch
Spean. The inclined shelves opposite to the mouth of Glen
Turret (See the diagram, Plate VII. fig. 6.) are evidently
the effect of the water of Loch Roy, rushing off at successive
elevations, during its final evacuation; or perhaps, indeed,
some of the lower ones may have been owing entirely to the
after operations of the river. Generally towards the mouth of
Glen Roy, and particularly to the eastward of the Hill of Bo-
huntine, the valley has been much deepened by the river, and
the rocks are more and more cut, as it proceeds in its progress
down the glen; we are not, therefore, to decide upon the
depth of the ancient lake at this point, by what we now see.
The same deepening of the channel of the river takes place in
the common valley of the united Roy and Spean, as is exem-
plified in the wild scenery at Highbridge, to which direction
the river Pattaig was turned, and whither the whole water of

these

OF LOCHABER. ~ 61

these valleys was then sent and discharged, instead of going
as formerly through the Pass of Muckul towards the Kast Sea.
The state which matters had now assumed, will be understood
at one view, by a reference to Plate VIII. fig. 4. Glens Gluoy
and Roy were now completely evacuated of their stagnant wa-
ter. But of the Glen Spean lake, besides those remnants that
remain to this day under the name of Lochs Treig and Laggan ;
there were then three smaller portions, as represented in fig. 4.
These must have long survived the great catastrophe, since
the name of Kenmuir, or The End of the Lake; given to each
of the rocky necks of land, which served as barriers to confine
their western or lower extremities, sufficiently denotes that
these minor lakes, must have continued to exist after the Gae-
lic language was in use. It is a remarkable coincidence, and
worthy of notice, that the little valleys remaining after the dis-
charge of these smaller lakes, exhibit the same ravines and
falls, that accompany all those on the greater scale in this
neighbourhood, and that also appear in the case of the analo-
gous example of Subiaco in Italy. The causes which produ-
ced the evacuation of these smaller lakes, were evidently slow
in their operation; it must have been gradually effected by
the river alone working in obedience to that invariable law,
by which running-water has a constant tendency to reduce the
course over which it flows, to one uniform and regular decli-
vity.

From all that has come under my observation in the course
of this interesting investigation, I am satisfied, that the district
of Lochaber, and the country connected with it, will be found
to merit frequent and minute inspection; and that it will be
considered as affording many facts, from which important geo-
logical inferences may be drawn. It appears to me, that the
evidence displayed by its different parts, is admirably calculated
to illustrate all the varied mechanical operations of stagnant

and

62 ON THE PARALLEL ROADS

and of running water, under every modification ; and that per-
haps, these could be no where so well established. But this
is not all ;—for if, as I am inclined to believe, it shall ulti-
mately be decided, that the Glen-mor-na- Albin, not only elu-
cidates the mode in which the ancient lakes of Lochaber were
evacuated, but that the shelves left by these lakes also, throw
a reciprocal light upon the origin of the Glen-mor-na-Albin,
then the science of geology will have reaped no inconsiderable
advantage, by the attention of its followers having been direc-
ted, as I hope it will be, to such a field of inquiry.

NOTE.

Tue descriptive part of this paper, was written from my
notes, soon after returning from my last visit to Glen Roy.
I have just had (January 1818), an opportunity, of reading
for the first time, Dr MacCuttocn’s learned and ingenious es-
say “ On the Parallel Roads of Glen Roy,’ which was read at
the Geological Society of London, nearly about the time that
the Royal Society of Edinburgh did me the honour of listen-
ing to my first remarks on the same subject. I observe, that
I have the misfortune to differ very materially from Dr Mac-
Cuxtocu, as to the height of Shelf 2d, or the uppermost line
of Glen Roy, when considered with reference to Loch Spey.
As will be seen by looking at the text, (page 33, of the fore-
going), I conceive that this line may be traced to within about
200 yards of Loch Spey, and that, from the present level of
the ground there, having been increased by the accumulation
of a mossy stratum, I believe the level of the shelf to be ac-

tually

OF LOCHABER. 63

tually somewhat dower, than the surface of the moss lying be-
tween it and Loch Spey. In Dr MacCuttocu’s Tabular View
of Elevations, he makes the highest parallel of Glen Roy to be
1266 feet, and Loch Spey 1203 feet, above the German Sea,
and, consequently, the shelf to be 63 feet above the loch.
Although my own observations have led. me to form so very
different an opinion about this matter, and although this opi-
nion has-been since borne out by the highly respectable testi-
mony of Mr Macponatp of Inch, yet I should have almost
hesitated in supposing, that so very accurate and philosophical
an observer as Dr MacCuxzocx could have been mistaken, did
he not himself seem to imply a doubt in his own mind of some
error having arisen in the measurement of this very elevation.
This he expresses in a note which I hope Dr MacCuttocn’s
consideration will forgive me for quoting, as I doubt not his
liberality will pardon me for thus expressing my difference of
opinion with regard to the state of-a fact, of which I feel con-
vinced. The words of this note are as follows:
« Whatever doubt we may have respecting the general va-
«“ Jue of the method by which the elevation of the upper line
“ of Glen Roy was ascertained, I must here remark, that this
“ principal measurement receives confirmation, to a certain
“ extent at least, by comparison with the height of that land
« which is the common division of the Truim and the Garry.
« This point has been found, by levelling, to be 1460 feet, and
“ it appears probable, from comparing the course of the for-
“ mer river and that of the Spey to their common junction,
“ that the source of the Spey cannot be materially different in
“ elevation, a circumstance confirmed by the barometric ob-
“ servations. The other measures in the Table scarcely ad-
“ mit of any material errors.”—Geological Transactions,
Vol. iv. Part ii. p. 327.
The

64 ON THE PARALLEL ROADS OF LOCHABER.

The height of the source of the Truim is here stated to be
1460 feet; and it is supposed by Dr MacCutzocn not to be
materially different from that of the source of Spey, which,
however, is only 1203 feet by his measurement. According
to this statement, therefore, the source of Truim is 257 feet
above that of Spey, which, in a question of so much nicety as
the present, must be considered as constituting a very mate-
rial difference indeed. But the difference between Dr Mac-
Cuxxocu and me, is only about 63 feet, which, if it can be al-
lowed me, will bring the height of the sources of the Truim
and Spey so much nearer to an equality, and will at the same
time make the altitudes relating to Glen Roy, in perfect har-
mony with the view of the state of matters which my observa-
tions have led me to entertain, are

I].

‘deur ayg ut » purod
apy -oyytuia Sp ponnatne x

yoy upg 0 eng “I ——eruangsip 0 zo uses suialy wage

moa ApIULarpERa ca ddm sjryy sq ayy wo AOMITION WI

TAO DP MIA

i

TROT IT 10 REPT "20S TAY 'SUD4E

wo gunad siloud 9 —hacoppray Tay Pareayaur BS—myp Frag Fry yb 28 aby 7g P—aununyeg JO 2 a — dep eg G—haenyop jp

edwuc a a Wig jue di ure af We Uy, DA Oar TULOLE Wes FE NVtdS NOWID P uw KO IL Wir yo suo Wor ay} Jo ASH TAL

geuraprary emunig Sg BYPYS

TIT AT 224 UP IOS QnA y “wun 7a

ms A AR
1P IL AT JE ° Trans. Royal Soc. Edin? Vol. LE Part l.

The GAP as seen from GLEWCOLLARIG taken from point ¢ in the map.

a is the Full of Bolunime

SR a ee ; Brgreves by Welln Biden
by Thomas Lande Fie. 2
g-2.

The GAP as seen from GIUBNROY taken from poimt ¢ im the map.

a us the hill of Bohunitsne

|

Vad. IX. Partl.

Frans. Royal Soc, Edin”

PLATE IV.

Engraval by

Stetehed by Thomas Latder Dick

The foreground remrestvils a Shelf, with @ 70k he Lhe WueTIOT GPGlE

Thans, Royal Soc, Ridin? Vol, IX Part LZ.

PLATE Vo

Skeehed by Lhomas Lauder Dick

the may

ROY taken from yp

LEN]

a
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W of the head of G

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4

VY TE

the foreground ts a portion of Shelf 3%

which the Rov comes

ravine through

ymbhran —b tsotated rock dividing upper and under Glen Rey — ©

“

Mountain. of T.

a

PLATE

Lrans. Royal Soc. Bdin® Volt. IX. Partd,

Wi.

Miller Ratire™

Engraved by

NhetrAnd by Lhorite Laruiter Dick:

f from poimt g im the map.

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PILATE

Frans. Royal Soc. Edin? Vol. 1X. Part Z

Pig. 3 é

5
Resale
\ (\ \\)

Fig. I.

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Lauder Dick Delt

Them

DIAGRAMS

shelves.

Fig 5, Theory of the formation of a Shelt_Fig 6. Glen Roy pseudo

0

Mey of Subvac

Map of the Va

Section of the Valley of Subiaco_Lig 4.

z,

Lig 3

Seotion of the barrier rock.

rock of the Valley of Subiaco_fig ?.

Fig i The barrier

PLATE VILL.

Trans. Royal Soc Badin? Vol, IX ParteL,

i Dy

Itt a,

of the LAKES

ates

st

r differemt

DIAGRAMS to ilimstrate the theo

my of the fou

lakes. Rig 2 State of Loch Ley atter its tint subsiilence

matters attr the second subbidence of Zoch

Hig 3 State of

SS

Ba A
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Trans. Royal Soc, Edin” Val ZX. Purel

j jel

i

Di
cm

A ILA

Mowiaig the Adfernt tines of

HORIZONTAL SELIELYES

an the
CAGEINS, OF ILO CRSA

II. On the Poisonous Fishes of the Carribbee Islands. By
Wiuram Fercuson, M. D. F. BR. S. Evry.

(Read Jan. 18. 1819.)

Te subject of poisonous fish has long been a source of
puzzle and speculation to the inhabitants of the West Indies.
Much has been conjectured upon it, and numerous tests and
theories been proposed, which have had for a time their be-
lievers and advocates; but all have been found to be equally
baseless. The author of this paper, by a narrative of what he
has himself seen and observed on the subject, proposes rather
to shew to the Society what it is not, than what it actually is,
and thereby to clear the way for the future successful investi-
gation of this curious and interesting phenomenon, by dissipa-
ting many erroneous notions that stand in the way of ‘ee dis-
covery of truth.

‘Tamoaebaet the greater part of the West Indies, the acci-
dent of meeting a poisonous fish is a rare and extraordinary
occurrence. At Barbadoes, for instance, it happens so seldom,
that the majority of even the best informed inhabitants can
scarcely be made to believe, that it has ever taken place

VOL. IX. P. I. I amongst

66 ON THE POISONOUS FISHES

amongst them. On the coasts of St Domingo, where I served
during the years 1796, 1797, and 1798, and where the British
troops, under the scarcity of fresh provisions, always depended
much on the sea for subsistence, only two well-authenticated
instances of the kind came within my personal observation.
Had there been others in the army, it is most probable that I
would have heard of them. ‘The nature of the accident, and
of the morbid phenomena consequent upon it, was so very si-
milar to what I had much more recent opportunity of witnes-
sing at Guadaloupe, in the year 1815, as to render it unneces-
sary to trespass on the time of the Society with a detail of
both occurrences. I shall therefore proceed to lay before
them an account of the last, as being the best within my me-
mory, as well as being officially authenticated by documents
that will be referred to in the course of this paper.

Shortly after the last capture of that island, under circum-
stances much the same as at St Domingo, while the British
troops were daily making use, without scruple, of whatever
fishes were offered to them in the markets of the island, the
Quartermaster-General, attracted by the appearance of a par-
ticularly fine horse-eyed cavallo *, purchased it for his family,
the members of which, including servants, were numerous (not
fewer than twenty). All partook of it, and all, without excep-
tion, were taken ill within a few hours afterwards. The symp-
toms in some were cholera morbus, with florid patches on the
skin, not unlike what is seen in phlogistic scarlatina, only the
parts affected were more swelled and raised; and, in all,
great and most distressing pains over the thinly covered
bones, more particularly the bones of the face, with great fe-

brile

* Harang aux gros yeux of the French, and Scomber of naturalists.

OF THE CARRIBBEE ISLANDS. 67

brile disturbance, much painful numbness of the soles of
the feet, and more or less of spasmodic twitchings and tre-
mors. All the Negro servants were more. severely affected
than the white members of the family, and the black cook
died from the effects of the poison ; confirming the popular
opinion, from the fatality thus falling, as in other instances,
upon the blacks, of their constitutions being more amenable
to the action of the fish-poison than those of the whites. But
it ought here to be remarked, that these last suffered exactly
in proportion as they had partaken of the fish, and the Gene-
ral’s lady, who. had dined almost entirely upon it, felt the ef-
fects of the poison for many months afterwards. The numb-
ness of the feet, with the peculiarly painful sensation of the
soles, continued for a very long time. So. little danger was
apprehended by the inhabitants from the use of this fish,
though all of them knew it to be occasionally poisonous, that,
two days after the accident, I saw a very large one cut up, and
distributed in the market-place amongst a number of spurcha-
sets, all of whom treated my interference with merriment, and
jeered good humouredly at my warnings against it.

» Though the majority of the British Medical Staff had long
been resident in the West Indies, the accident in the Quarter-
master-General’s family was so new to most of them, that we
hesitated not to call in the aid of the French Faculty of the
place, who prescribed (the necessary evacuations having been
premised) the sulphuret of potash in the first instance, in as
large and frequent doses as the stomach could bear, and then
the saccharine mucilages, in every shape that could be offer-
ed; and this treatment, more particularly that of the saccha-
rine regimen, appeared to be very effectual. It did not appear
that the alkaline remedy produced much effect. A very short
time after this occurrence, a shoal of the green-backed caval-

12 loes

68 ON THE POISONOUS FISHES

loes (a much smaller fish) beset the shores and wharfs of Basse-
terre, the capital of the island, in such numbers, that they
were taken in all kinds of ways by the common people, and an
English merchant, attracted by the sight of this fishery, could
not resist the temptation of a remarkably fine one, which he
purchased for a trifle, and carried home to his family. They
were taken ill after eating it, much in the same manner as the
Quartermaster-General’s, though not so severely*. His lady
only had alarming symptoms; but, amongst the many thou-
sands of these fish that had been eaten in the town, this one
alone was ascertained to have possessed any poisonous quali-
ty. The British Medical Staff was in the closest communica-
tion with the French Faculty on the subject, in consequence
of the first accident, and if any others had occurred, it is next
to impossible that they could have been concealed from us T.
These casualties strongly excited the attention of the Go-
vernor-General, Sir James Lerru, who directed me to call offi-
cially upon all the French Faculty, (some of them men of
much knowledge and experience) for information on the sub-
ject ; and from them we learnt, that sixteen different species
of fish had been found more or less poisonous, at different
times, in Guadaloupe ; but that in all, with one exception (that

‘ of

* 'The fish is, comparatively to the horse-eyed cavallos, a much smaller one,
and consequently a small portion only could fall to the share of each member.

+ Let it not be here supposed, that this fish-poison bears any analogy to the
affections that are sometimes induced upon particular constitutions in this coun-
try, from eating some particular kinds of shell-fish. The fish-poison affects alk
who receive it, as generally, and as certainly, as opium or arsenic. In the year
1797, at Cape Nicholas Mole, in St Domingo, almost every officer in the Army
and Navy suffered from it, from eating of one large fish, on the occasion of a
garrison dinner, and several of the black domestics died.

OF THE CARRIBBEE ISLANDS. 69

_ of the yellow-billed sprat *), it was so perfectly am accidental
occurrence, that it never had been deemed necessary to im-
pose any prohibition, beyond what the fears and experience
of the people naturally dictated, more particularly, as the best _
part of their food was at all times derived from the sea. From
their information, however, it was clearly ascertained, that the
most dangerous fishes were the small yellow-billed sprat, the
baracoota +, and horse-eyed cavallo, which three were forbid-
den under penalty of confiscation of the fishing-boats, to be
‘ever exposed for sale; and the other thirteen kinds were di-
rected, under a severe pecuniary penalty, to be gutted as soon
‘as caught, (thé black fishermen having expressed much con-
fidence in that precaution) and never to be brought to the
markets except in that state. No accident occurred after
these regulations were adopted, during the remaining nine
months that the British continued in possession of Guada~
loupe. From the black fishermen we also obtained the curi-
ous information, that the deadly yellow-billed sprat was never
poisonous when caught in the immediate Bay of Basseterre,
even at the time when it would be almost certainly fatal to eat
them if taken at a very short distance on either side of the
roadstead, and that, at. some seasons of the year, they could
be eaten with impunity everywhere ; the most dangerous times
with them being from the month of April till the end of the
summer months. They also amply confirmed, what we had
previously taken for granted, that the larger fishes followed
and preyed upon them at all times with avidity, and that there
was no bait they could use more tempting than the yellow-

billed

* Sardine doré of the French, and Clupea Thryssa of naturalists.
+ La Bechune of the French, and Perca major of naturalists,

70 ON THE POISONOUS FISHES

billed sprat. Indeed they might be seen by any who would
take the trouble to attend to mes selecting from their sprat-
nets the yellow-billed for bait, reserving the balahoo, a fish
not unlike the sprat, but about the size or a pilchard or small
herring, and the common white sprats of the same size, caught
in the same net, of the same shoal, and on the same ground,
for market ; which last were never known, under any circum-
stances, to prove poisonous.

The importance and obscurity of the subject, on which so
little light had been obtained from our inquiries at Guada-
loupe, called for further investigation, and by direction of Sir
James Lerru, I circulated the following queries, amongst the
faculty of all the colonies :

“ 1, What fish have you knowledge of, as possessing, when
eaten, a poisonous quality, in the West Indies ?

“ 2 Were these fishes poisonous in all places and seasons,
or only at particular times, and in particular places? Did
they prove poisonous to the ‘majority of those who ate them,

or only to particular individuals ?

“ 3. Did the other fishes inhabiting the same places, exhi-
bit, when eaten, more or less of the same poisonous quality,
or was it found in only one or two particular species, or only
in one or two individuals of the same species ?

“ 4, Can it be ascertained whether any species of food, that
fishes incidentally eat, can communicate this poisonous qua-
lity ?

« 5. It has been seen, that fishes such as the King Fish *,
and the different kinds of cavalloes, can be eaten with baley

when

Ee

* Xiphias of naturalists.

OF THE CARRIBBEE ISLANDS. 71

when of the ordinary size, but become sometimes poisonous,
when they grow very large. What do you suppose can be the
reason of this? Do these fish live on a different kind of food
when arrived at this gross state, from what they did when
smaller? Does the poisonous quality reside in the fat that
has accumulated under the skin ? or what is the change indu-
ced upon the fish in consequence of his increased bulk, that
renders him poisonous ?

“ 6. Are not fishes that are found to be poisonous general-
ly in the highest season, and of superior flavour ?

«¢ 7, Has any thing remarkable ever been detected in re-
gard to the liver or other viscera of poisonous fishes, or are
there any marks by which they can at all be distinguished
from others of healthy quality ?

“ 8. Is any faith due to the test of boiling a piece of silver
in the same pot with the suspected fish, when cooked ; and
will not all fishes that abound with dark-coloured fats under
the skin, imbue silver, more particularly when long boiled,
with a tint of the same? Have not these fishes been eaten
with impunity after they had stained the silver that had been
used for the above test ?

“ 9. Has the existence of copper-ore at the bottom of the
sea, so as to constitute what is called a copper-bank, in contact
with the waters, ever been ascertained; and if ascertained,
have the fishes caught there Lanai more remarkably poison-
ous than in other places ?

“ 10. Do fishes eat any species of marine plants, weeds, or
mosses, for food, and can any of those that fishes eat have the
effect of rendering them poisonous ?

“11, Are eels, mud-fish, and other species that live station-
ary in a great degree, amongst the weeds at the bottom of the

sea,

72 ON THE POISONOUS FISHES

sea, ever poisonous, or more remarkably .so than the other
species of fish that prey abroad throughout the waters ?

“ 12, The poison of the yellow-billed sprat has been found
particularly deadly in the month of May, at the time when,
according to the vulgar saying of fishermen, coral is in blos-
som. Can it be ascertained, what is the food of these fish at
that time? What particular species of marine insects abound,
and sea plants flourish, at that period, in the places where he
inhabits 2”

N. B. It is said that the yellow-billed sprat can be eaten
with impunity at all seasons, when taken in the road ot
Basseterre, Guadaloupe. é

“ 13, Do not all the larger fishes that are found to be poi-
sonous, prey upon the yellow-billed sprat, in common with
any other kind of smaller fish they can master? May not the
larger fishes, that prey directly upon the yellow-billed sprats,
thereby acquire a highly poisonous quality, or one of less in-
tensity, by preying at a farther remove on those fishes that
have done so; or is this disproved, by the fact of the larger
fishes of some species only being poisonous, while the smaller
of the same kind, that may be supposed to prey more imme-
diately on the yellow-billed sprat, can be eaten with impu-
nity 2”

N. B. The poisonous quality of the Baracoota is in no re-

spect modified by his size.

“ 14. Fish of the larger kinds are never poisonous at Bar-
badoes, and some other places. Is the yellow-billed sprat
found on these coasts ?

“ 15, Is any credit due to the common opinion, that fish
are rendered poisonous by eating the gally fish or stinging
blubbers ?”

N. B.

OF THE CABRURRE ISLANDS. 73

.N. B. These blubbers are ae in)great. quantity at Barba-
does,’ and. aiund prodigiously on some of the coasts of
Si «| <Europe; where, fish are never known to be poisonous.
. 16, What. are the symptoms of fish: poison : ?. Do they
bear. any) resemblance, to those of the poison of copper or other
mineral. poison, or poison’ from: the vegetable kingdom? Is
there any antidote against it that can be used at table, such as
oil, Fagaios yinegar,, wine, |spirits, or, spices, and what are
the best temedies and modes of treatment after the poison has
taken effect 2”: iw JI .e1odto os ctea rood) dors!

3 a } ’ 7 ” ? if c
gy) Je bedgilic : JOSHI

o The: repliens Si6in the magjatity abe even’ athe older, ot
in the’ West Indies professed. total i inexperience of the subject,
So rare it seems’is:the accident’; but from others of them some
valuable information was. Lately From. the;account-of my
frietd Dr Nucenr of ‘Antigua, it (would: eipean! that: the yel-
low-billed sprat ‘is’ at» times the strongest: native! unprepared
poison probably in existence, Negroes having fallen down dead
when ‘in the act of eating it, with part of the fish, though a ve-
ry small one, in'their mouths; ‘and the same effect ‘has been
produced on a dog, from giving’him a single fish to eat. It is
even recorded by Dr Cuisnoxm of Grenada *; that a) white
person, having unwarily, when eating sprats, put one of the
yellow-billed into his mouth, and immediately’ spit it: out
again, when informed of his mistake, without swallowing any
portion, but only masticating it, died nevertheless from the
effects of the poison. These accounts were confirmed by Mr
Grrrin, staff- “surgeon of St Kitt’s, who stated a remarkable

’

VOL. IX. P. Ie a K , occurrence

* In the Number for October 1808 of the eee Medical and Surgical
Journal.

viet ON THE POISONOUS FISHES

occurrence of the kind that had lately taken place in that
island. Dr Ossorne of Antigua, by whom all the above was
fully admitted, professed, nevertheless, much confidence in the
precaution of gutting the fish, and stated an instance of a
Creole lady, who would venture to eat the yellow-billed sprat
at all times, when she could depend on the fishermen cleaning
them out as soon as caught; but this must in all probability
have been owing to peculiar idiosyncrasy in the person, as no
cleaning out of the fish, however promptly and perfectly per-
formed, rendered them safe to others. It was proven at the
same time, by a report from an eminent physician at Marti-
nique, transmitted through Staff-surgeon Woutre, that not
even salting the fish after cleaning it, could at all times do
away the poisonous quality ; a family in that island having just
been severely poisoned by eating a baracoota that had been in
salt twenty-four hours. The blacks always profess the ut-
most dread for the yellow-billed sprat, during the months
when, according to their vulgar saying, the coral is in blossom,
but at other times they eat them without scruple, and with im-
punity, giving no other reason but that the season of danger is
past. I see no room to doubt of the madrepore being in par-
ticular activity at certain seasons of the year, and that fisher-
men are more sensible of the growth of coral at these times
than at others; but 1 think there is much reason to doubt of
this growth at all affecting the quality of the fish that feed up-
on the corallines, seeing that Barbadoes, which is a coral for-
mation in all its coasts and shores, is of all the islands in the
West Indies, the one, I believe, where poisonous fish are most
rarely seen. Besides, it is not on the coasts of coral formation
where these animals are commonly found. Antigua may be
a partial exception ; but their more favourite resort would ap-
pear to be the shores of the volcanic islands of the West In-

~ dies,

OF THE CARIBBEE ISLANDS. 5

dies, such as the leeward shore of Guadaloupe, immediately
under the great Souffriere, where hot boiling springs are found
within the high-water mark, or in the channel between the
volcanic promontories of St Kitt and St Bustatia, where the
fish are so remarkably poisonous, that fishermen rarely exer-
cise their trade in that part of the sea. It abounds, I have
heard, in a particular manner, with the yellow-billed sprats,
and no inhabitant will venture to eat a baracoota or other
large fish taken thereabout.

Most of the accounts agreed in what I had myself obser-
-ved, of the fish that proved poisonous being always in the ve-
ry best condition, and generally the largest of their species,
without marks of disease of any kind in any part of them, and
I never heard of a single exception to this, the sufferers ha-
ving always been induced to eat heartily, from the peculiar
excellence of the fish; and all who were capable of examining
the subject, were convinced of the inutility and frivolity of the
tests usually employed, such as boiling a piece of silver, &c,
with the fish, adducing instances mae the severest poison
had been received when the test declared security, and vice
versa ; the only test hitherto discovered, in the least to be de-
pended on, being that of giving a portion of the fish, the offal
in_preference, to a cat, a duck, or a pig, and witnessing its ef-
fects upon them, before proceeding to make use of it.

The commonly received opinion, too, of copper banks at the
bottom of the sea, that is to say, uncovered and insoluble cop-
per ores in contact with the waters, the very existence of
which is a most improbable gratuitous supposition, communi-
cating a poisonous quality, such as that found in the yellow-
billed sprat, to the wandering fishes that roam in the waters,
I need scarcely say to the Society, was refuted, and shewn to
be impossible; as well as another opinion, almost.as general,

K2 that

6 OF THE POISONOUS FISHES

that the stinging blubbers (the Meduse and Holothurie) which
we have no reason to suppose that fishes ever eat, communi-
cated the poisonous quality. Another article in the creed of
the French Creoles on this subject, viz. that fish were made
poisonous by eating the deadly manchineal apples that were
carried by the rivers into the sea, was too absurd to be inves-
tigated, as its obvious refutation was at once conveyed, in the
fact of no poisonous fishes having ever been found in any! of
the numerous rivers that flowed or stagnated amongst groves
of the manchineal tree; but they believed it from the curious
circumstance which induces me to mention their opinion here, .
of the sea-water being an excellent remedy against the man-
chineal poison ; and they therefore believed, that from having
the remedy so perfectly at hand, the fish could eat with im-
punity what made him so dangerous an article of food to those
who catched him.

From the whole of our inquiry, I think it was established,
that no fish, with the exception of the yellow-billed sprat,
which, from its small size, is fitted to be'the prey of almost
every other, could be called regularly or certainly poisonous
at any time; but that with all the rest it was an accidental: va-
riety, communicated from some particular kindof food. ‘That
in the larger fishes of prey, the poisonous quality most pro-
bably arose from their having recently preyed upon the yellow-
billed sprat (these fishes being found most frequently poison-
ous where the yellow-billed sprat abounds), but in all of that
description, it would appear’ to be a transitory quality, com-
municated to the animal from the food he had just eaten, and
passing away soon after its digestion was completed ;—a sup-
position the less improbable, when we 'consider‘the quickness
of the process of digestion, that, front the shortness of the ali-
mentary canal, and great size of the liver, must'take place in

these

OF THE CARRIBBEE ISLANDS. 77

these voracious animals. How else are we to account for the
fact so often witnessed by ships crews, or in fleets, of two dol-
phins caught on the same line, the one proving wholesome,
the other poisonous ; or, amongst other species, for one or two
only of a shoal, caught in the same net, proving dangerous to
eat; or for the chances being so much greater, of falling in
with the larger poisonous fishes, where poisonous prey
abounds, yet the poisonous quality of the former never being
sure or permanent ? I have laid so much to the account of the
yellow-billed sprat, that I was long much puzzled to account
for: well authenticated: instances of the larger fishes having
more than once, though certainly very rarely, been found poi-
sonous at Barbadoes, on the coasts of which I-believe that the
yellow-billed sprat is never seen; and it was not till after I
had been,a long time .in, the island, I ascertained beyond all
doubt, that the smaller Jack jish, a species of the Perca ma-
rina, well. fitted from) their size to serve the same purpose of
prey|to'the larger fish as the sprats, were occasionally poison-
ous in some ofthe bays at the north-east end of the island.

, Could, we ascertain what it, is that, communicates) the poi-
sonhous, quality to’ the, smaller ‘fishes ‘mentioned in this paper,
the question, in, respect to discoyery: of .cause, might be consi-
dered) as. at rest.. The existence of a local marine poison, when
eaten/by.the fish; communicating noxious impregnation, or in-
herent, poisonous quality, in, these little animals, may both be
inferred,and'; disproved’ on nearly equal. grounds. The first
would:seem- very probable, from. the local and temporary na-
ture of the,,quality ‘in, regard . to place, and season, were it not .
that the dreadful potency. of the impregnation renders. it. most
unlikely that it could be derived from any species of food
whatever, or be otherwise than inherent in the fish, to say no-
thing of its incommunicability, in the case of the yellow-billed

; sprat,

73 ON THE POISONOUS FISHES

sprat, to other fishes of the same size and genus, such as the
white sprat, which is always found in the same place, and may
be supposed to feed in the same way.

. The subject is of great importance, for no misfortune can be
conceived more terrible, even when death does not ensue,
than being served with this undistinguishable poison in the
shape of the edible fishes, the best and most delicious, as well
as the most: common food by far, which the Caribbee islands
afford. Most pitiable cases were related to me in the French
settlements, by persons worthy of credit, where the patients,
after escaping with difficulty, from imminent death, suffered
during the rest of their lives all the miseries of exfoliation of
the bones with hideous ulcerations, or paralysis, and all its di-
stressing accompaniments ; and the same accounts are confirm-
ed by Dr Tuomas, who practised long in the West India colo-
nies, in the 2d edition of his Practice of Physic. For these
secondary symptoms no adequate remedy could of course be
found; but as an antidote to the poison, before it could have
time to operate in this baneful manner, there could be no
doubt of the astonishing efficacy of sugar, more particularly in
the form of the expressed cane juice. This fact was establish-
ed by a great body of evidence, and to my mind it in some
degree explained the curious circumstance of white guests ge-
nerally escaping better from the fish-poison than their black
domestics, at the same entertainment; the former making
use of punch, sweet liqucurs, &c. which seldom fall to the lot
of the latter, for we had no clear proof of any spice or season-
ing, or vinous or spiritous liquor, that did not contain sugar,
possessing any efficacy as an antidote.

OF THE CARIBBEE ISLANDS. © 79

I feel that I owe an apology to the Society for having thus.
offered a paper to their notice, which proves so little; but the
subject belongs to an element into which we cannot enter, and
all familiar knowledge of its inhabitants. must consequently be
impossible.

II,

abating Srna
rr sua RANE

ee ay PR ep: |
wg “NOH pean 0
lie Fale vane REG ern f

Ill. Account of a Mineral from Orkney. By Tuomas Srew-
art Trait, M.D. F. BR. S. Eni.

(Read April 21. 1817.)

Wane examining an abandoned. lead-mine in the vicinity
of Stromness, in the year 1803, I found a mineral which, from
its weight and appearance, I supposed to be carbonate of ba-
rytes. A few hasty experiments soon convinced me that it
was a different substance ; but circumstances occurring which
prevented a,more accurate investigation, the mineral lay ne-
glected among the duplicates of my collection till last autumn,
when having mentioned my doubts and conjectures respecting
it to my friend Dr Murray of. Edinburgh, I was strongly
urged by that gentleman to undertake its analysis. During
his short visit to Liverpool, a few preliminary experiments
were begun, from which it appeared, that the mineral contain-
ed carbonate of strontia, and I have since completed its che-
mical examination.

I may here observe, that a specimen having previously been
submitted to several very able mineralogists, they were un-
able, from its external characters, to ascertain its nature; a
circumstance which affords a fresh proof of the necessity of
uniting chemical investigations to a knowledge of the external
appearance of mineral bodies.

VOL. IX. P. I. L External

82 ACCOUNT OF A MINERAL FROM ORKNEY.

External Characters of the Mineral.

-Irs colour in the fresh fracture is greyish-white, passing
into pale yellowish-white, where it approaches the surface of
the specimen, which is weathered.

It occurs in masses, of various sizes, dispersed, along with
lead-glance, in a species of coarse slate, which may perhaps be
considered as shale passing into clay-slate*. This rock ap-
pears to rest on mica-slate, which is in connection with gneiss
and small-grained granite, rocks which occur in no other part
of the Orkney Islands constituting mountain masses. The
mineral perhaps may occur crystallised, for it has a distinct
crystalline texture ; but the specimens I found were so much
acted on by the weather, that no trace of crystalline figure is
discernible.

The lustre is shining and pearly in the principal fracture ;
glistening and resinous in the cross-fracture. The weathered
surface is earthy and dull.

The principal fracture is radiated, somewhat diverging ; the
cross fracture is uneven, approaching to splintery. The mine-
ral is translucent where fresh, but opake externally.

It is soft ; so as easily to be scratched by a knife ; it scratches
cale-spar, but not fluor-spar.

It is rather brittle, and easily frangible.

It is heavy. Its specific gravity is 3.7, or more accurately
3703, to water as 1000.

Chemical

* T here state my own impression at the time when the mineral was found : but
Professor JamEson, to whose authority I pay the greatest deference, has obser-
ved, in a work long ago printed, that the rocks in that neighbourhood consist of a
mineral intermediate between shistose and indurated clay."—Mineralogy of the
Scottish Isles, vol. ii. p. 283.

ies)
Oo

ACCOUNT OF A MINERAL. FROM ORKNEY.

Chemical Characters.

It is insoluble, or nearly so, in water.

It effervesces briskly with acids, and is partly dissolved.

It is infusible before the common blowpipe, and resists the
ordinary temperature of a smith’s forge, when subjected to it
in a crucible; but loses in weight, becomes white, and more
hard than before. This process rendered it partly soluble in
water, to which it imparted an acrid taste, alkaline qualities,
and the odour of sulphuretted hydrogen.

A fragment of the mineral, thrown into strong sulphuric
acid, effervesced, and formed a white powder of little solubi-
lity.

With concentrated nitric and muriatic acids there was, at
first, a brisk effervescence, which soon ceased ; but was repeat-
edly renewed, on successive additions of small quantities of
water. In both cases a portion was dissolved ; the solution
was transparent and colourless, and crystallizable on evapora-
tion. ayy

On adding prussiate of potassa and iron to the muriatic
solution, no change was at first perceptible; but after some
time, a faint bluish tinge might be distinguished. By digest-
ing muriatic acid on the insoluble residue, a deep blue colour
was obtained on the addition of the same re-agent.

Chemical Examination of the Mineral.

The preliminary experiments by which its chemical charac-
ters were ascertained, shewed that it was resolvable by the ac-
tion of muriatic acid into gaseous, liquid, and solid substances,
each of which became the subject of investigation.

L2 A.

84 ACCOUNT OF A MINERAL FROM ORKNEY.

A.
The gas disengaged was found by experiment to be carbo-
nic acid. ,
B.

1. The muriatic solution, when separated by the filter from
the undissolved residue, was evaporated to dryness, and cry-
stallised from a fresh solution in water *. The crystals were
slender prisms, with two of the lateral planes broader than the
rest ; were persistent in the air, and had all the chemical cha-
racters of muriate of strontia. Their solution was not preci-
pitable by ammonia, but pota’sa separates a portion of the
earth with the peculiar phenomena detailed in Dr Horr’s va-
luable paper in volume iv. Phil. Trans. Edin.

2. The nitric solutions gave small brilliant crystalline flakes ;
and these were also formed on the addition of nitric acid to
the muriatic solution, but were apeerty dissolved on the addi-
tion of water.

3. In order to satisfy myself still farther that the muriatic
salt had a base of strontia, a very dilute solution of sulphate of
soda was dropt into a concentrated muriatic solution of the mi-
neral ; but no precipitate was formed: when the sulphate was
less diluted, a precipitate fell, though less copious than when
added to a similar solution. of muriate of barytes, but more
abundant than with muriate of lime.

4. After separating, by successive crystallizations, the cry-
stals from the muriatic solution, a small quantity of an acrid

and

* The first addition of water caused a considerable evolution of caloric.

ACCOUNT OF A MINERAL FROM ORKNEY. 85

and very deliquescent salt remained in the bottom of the cap-
sule. It was decomposed by oxalate of potassa, when a high-
ly insoluble substance, not soluble in excess of oxalic acid, was
obtained. Calcination, and the action’of sulphuric acid, pro-
ved that the oxalate of lime had been formed.

5. The greyish-white powder, which remained after the cal-
cination of the oxalate, was wholly soluble in water, and form-
ed a bulky precipitate with sulphuric acid. The washings of
this precipitate were not rendered turbid by phosphate of am-
monia, nor was any change produced by the muriate of am-
monia. These experiments shew that the muriatic solution
of the mineral contained no magnesia, nor argil, nor any ap-
preciable quantity of iron. :

The peculiarity attending the action of concentrated nitric
and muratic acids on the mineral is worthy of notice, as afford-
ing an additional diagnostic mark between carbonate of stron-
tia and carbonate of barytes. It will be recollected that those
acids acted at first upon the mineral from Orkney, but that
the effervescence soon ceased, unless water were added. In
order to compare the two carbonates more accurately, the fol-
lowing experiments were instituted.

a. A fragment of native carbonate of strontia from Strontian
was thrown into muriatic acid ; a strong effervescence ensued,
but soon ceased : it was however immediately renewed on the
addition of water ; just as had happened with the mineral from
Stromness.

b. Into a portion of the same acid was dropt a fragment of
carbonate of barytes from Anglezark, which had been entirely °
freed from loose particles ; no effervescence took place, until
water was added ; but when a portion of the same specimen,
reduced to powder, was thrown into-a fresh portion of the

acid, effervescence instantly commenced.
c A

86 ACCOUNT OF A MINERAL FROM ORKNEY.

c. A solid fragment of Carrara marble was attacked and dis-
solved by a portion of the same acid, without the addition of
water.

Hence we may consider carbonate of strontia intermediate,
in its habitudes with this acid, between carbonate of barytes
and carbonate of lime; and these peculiarities afford an easy
method of distinguishing these three native carbonates from
each other.

From the preceding experiments we may conclude, that
the portion of the mineral from Orkney, which is soluble in
muriatic acid, consists of carbonate of strontia, a little carbo-
nate of lime, and a minute trace of iron.

C:

The undissolved residue of the former experiments had a
yellowish-white colour, and was totally insoluble in water.
The calcination of a portion of the mineral had shewn that
sulphur entered into its composition, as sulphuretted hydrogen
was given out on the addition of water. The probable origin
of this had been the decomposition of a sulphate. No trace of
a sulphate had appeared in the acid solutions, and therefore
we may conclude that the sulphate exists in the insoluble re-
sidue.

1. A portion of this residue was boiled with a concentrated
solution of carbonate of potassa in a silver vessel. It was then
washed to free it from alkali; and on finding that it had be-
come partly soluble in muriatic acid with effervescence, the
process was severaltimes repeated, and thus the greatest part
of the residue was rendered soluble in muriatic acid. What
remained in the last process, was soluble in boiling sulphuric
acid, from which it separated on cooling in acicular crystals. -

2. The

ACCOUNT OF A MINERAL FROM ORKNEY. 87

2. The water employed to wash the powder C. |. was
evaporated, and crystals of sulphate of potassa were formed.

3. The muriatic solution (C. 1.) obtained by decomposing the
sulphate by carbonate of potassa, when evaporated, yielded ta-
bular crystals, persistent in the air, which, placed in the wick
of a candle, tinged its flame of a yellow or greenish-yellow
hue ; and when dissolved in water afforded an instant precipi-
tate with sulphuric acid, and with the most diluted solutions
of sulphate of soda.

4, Another portion of the insoluble residue was boiled with
eight parts of concentrated sulphuric acid in a platina cup,
and was wholly dissolved ; but on cooling, it separated in aci-
cular crystals around the edge of the containing vessel. These
crystals were acidulous, even when dipt into water, which
resolved them immediately into an insipid powder which was
a neutral sulphate. When exposed to the air this powder was
more slowly formed.

5. A third portion of the insoluble residue was digested
with muriatic acid, under the idea that its colour indicated the
presence of iron. The acid became of a yellowish colour,
and afforded a rich blue precipitate with prussian alkali.

These experiments prove, that the residue consists chiefly
of Sulphate of Barytes. In C. 1, the process of Kuaproru was
employed ; and.at each successive step, fresh portions of the
sulphate were decomposed, by the united affinities of sulphuric
acid for potassa, and of carbonic acid for barytes. In C. 4.
Morertr’s process was followed *, and, to verify his results,
comparative experiments were tried.

a. Artificial sulphate of strontia was boiled in a platina cruci-

ble with 8 parts of concentrated sulphuric acid ; a perfect so-
lution

* See Tuomson’s Annals, vol. iv. 395.

88 ACCOUNT OF A MINERAL FROM ORKNEY.

lution took place; the liquor was poured into a glass capsule,
and put aside in a cool place; no crystals appeared in 12
hours; but after several hours a thin ring of amorphous sul-
phate was deposited around the margin of the liquid, probably
owing to the absorption of water from the air. The insoluble
neutral sulphate was however immediately precipitated from
the solution by the addition of water.

6. Artificial sulphate of barytes was treated in the same
manner ; a perfect solution was obtained; and the liquid soon
began to form crystals around the edge of the capsule. When
the air of the room is dry, the crystals though small are pretty
distinct prisms, promiscuously aggregated. They are super-
sulphates, agreeing in their properties with what is stated a-
bove (a).

ce. Fragments of a transparent crystal of sulphate of strontia
from Bristol, reduced to powder, presented exactly similar re-
sults with the artificial sulphate (a); and a portion of a co-
lourless crystal of sulphate of barytes from Dufton near Ap-
pleby, was acted on precisely as the artificial sulphate (6).

In the mineral from Orkney, the whole of the residue in- .
soluble in nitric and muriatic acids, was dissolved by boiling
sulphuric acid ; which shews that there is no silica present.

The blue precipitate, by prussian alkali, from the muriatic
acid digested on the residue, shews that oxyde of iron is uni-
ted to the sulphate.

The mineral, then, consists of carbonate of strontia, carbonate
of lime, sulphate of barytes, and a little oxyde of iron. We have
yet to ascertain the proportions in which these ingredients
enter into its composition.

D.

To ascertain the quantity of carbonic acid is important, as it

will enable us to verify the other results.
100

ACCOUNT OF A MINERAL FROM ORKNEY. 89

100 grains carefully selected from the purest and most solid
parts of the specimen were broken into small fragments, and
dropt in succession into a flask, containing a cubic inch of
muriatic acid diluted with two parts of water, which had been
- previously poised in a delicate balance. Each fragment was
suffered to part with its carbonic acid before another was ad-
ded, lest the violence of the effervescence should dissipate
any portion of the liquid in the flask. After all effervescence
had ceased for some hours, the flask was again accurately
weighed ; when it was found to have lost 21.1 grains. As
this part of the process requires peculiar attention, the experi-
ment was repeated ; and the average of three trials gave 21
grains as the quantity of Carbonic Acid in the mineral.

This result cannot be far from the truth, as it was the same
when nitric acid was employed.

E.

To ascertain the quantity of strontia and lime, several experi-
ments were undertaken.

1. The muriatic solution D. was evaporated to dryness, in
order to expel the excess of acid. The saline mass was dis-
solved in water, and slowly evaporated ; the crystals of mu-
rlate of strontia were successively separated ; but the results of
several repetitions of the process not coinciding, a different me-
thod was employed to separate the muriates of strontia and
lime.

2. The nitric solution of the mineral was evaporated to
dryness, dissolved again in water, and slowly crystallized.
The crystals were digested with strong alkohol, by which ni-
trate of lime is dissolved, but not nitrate of strontia. The crys-
tals were washed by the affusion of alkohol; and thus the two
salts were completely separated.

_VOL. IX. P. I. M 3. The

90 ACCOUNT OF A MINERAL FROM ORKNEY.

3. The quantity of strontia in the mineral could be ascer-
tained by weighing the nitrate; but there appears to me less
certainty in weighing crystals which contain water, and which
are very soluble, than in reducing the earthy or other base
to the state of an insoluble compound, that may be moderate-
ly heated without loss of weight, and the constituents of which
are well known. Sulphuric acid was therefore added, in ex-
cess, to precipitate all the strontia, and the liquid being eva-
porated to dryness in the capsule in which the precipitation
was effected, and heated in a platina crucible to expel excess
of acid, and water, afforded 84.6 grains of sulphate of strontia,
which, by Dr Wottaston’s excellent scale, is equivalent to 68.6
grains of Carbonate of Strontites.

4. The alkoholic solution (KE. 2.) was evaporated, and afford-
ed a tenacious paste, which, when dissolved in water, precipi-
tated by carbonate of soda, washed and dried, weighed 2.6
grains; this, then, gives us the quantity of the Carbonate of
Lime which enters into the composition of the mineral.

When we compare these results, with the quantity of car-
bonic acid in the mineral, we find an agreement as exact as
the nature of such researches will permit : for

68.6 carbonate of strontites contains 19.60 carbonic acid ;
2.6 carbonate of lime contains 2 1.14 carbonic acid
20.74

or the difference amounts only to 0.26 per cent.

F.

The examination of the insoluble residue was attempted, by
boiling it with carbonate of potassa, in a silver vessel ; but as
only a portion was thus decomposed at each boiling, I thought
it best to attempt it in the dry way.

Having

ACCOUNT OF A MINERAL FROM ORKNEY. 9]

Having found in some previous experiments that some iron
adhered to the insoluble residue,

1. It was digested with muriatic Acid, which became of a
yellowish hue, and along with the iron took up a portion of
the earthy matter; but this was precipitated on the addition
of water. Its solution was concentrated, and precipitated by
succinate of potassa. The precipitate, washed, dried, and
heated to redness in a platina crucible, afforded 0.1 grain, or
nearly so, of red Oxyde of Iron.

2. The residue of the mineral was now mixt with three
times its weight of lamp-black, made into a paste with oil, and
subjected in a black-lead crucible for two hours, to the heat of
a smith’s forge. The contents of the crucible were then
thrown into muriatic acid, which produced a brisk efferves-
cence: the muriatic solution was precipitated by sulphuric
acid ; it was then evaporated and heated, to expel the excess
_of acid, and what water might adhere to it, and when weighed
= 27.5 grains.

The residue then consists of 27.5 sulphate of barytes,
And - 0.1 oxyde of iron.

27.6

In 100 grains, therefore, of the mineral from Orkney, we

have
68.6 carbonate of strontites.
27.5 sulphate of barytes.
2.6 carbonate of lime.
0.1 oxyde of iron.

98.8
1.2 loss (probably water).

100.0

92 ACCOUNT OF A MINERAL FROM ORKNEY.

A question may here arise, whether these ingredients are
chemically combined, or only in a state of mechanical admix-
ture in the mineral? The homogeneous appearance, and
crystalline texture of this substance, and the nearly uniform
proportions of the ingredients obtained from it, by different
experiments, would lead to the conclusion that the mineral in
question is a chemical compound. These, however, may be
the result of an intimate mechanical mixture of the earthy
salts of which it is composed.

The iron appears to be united by affinity to the sulphate of
barytes, as it is not separated in any considerable degree du-
ring the solution of the carbonates in diluted muriatic and ni-
tric acids; but requires for its separation from the sulphate of
barytes, digestion in one of those acids, after the separation of
the more soluble ingredients.

The existence of carbonate of lime in this mineral is en-
teresting. In this particular it accords with what has been ob-—
served by Scumeisser, THomson, and STroMEyeER, in native
carbonate of Strontia. It is remarkable, that the portion of
carbonate of lime in the Orkney mineral, is not very different
trom the quantity of carbonate of strontia in Arragonite ; a cir-
cumstance which renders it probable, that the carbonate of
lime is in a state of chemical union with the carbonate of
strontia.

Should this substance be regarded as a variety of Strontia-
nite, or as a distinct mineral species ? If the latter conjecture
be entertained, it will be necessary to give it a name; which
may be derived, either from its composition, as Bary-Srron-
VTANITE, or from its locality, as SrRoMNITE.

IV. Extract from Inspection Report of the Island of Trinidad,
made in the year 1816, by the Inspector of Hospitals, in
conjunction with the Quarter-Master General and Chief
Engineer for the Windward and Leeward Colonies of
the West Indies. By Wit11am Fercuson, M. D.
F. R. S. Epin.

(Read Dec. 1. 1817.)

Hayne heard at Port-of-Spain of an appearance that went by
the name of the Mud Volcanoes, we took the opportunity when
surveying the southern quarter of Trinidad, to examine them.
They are situated near Point Icaque, the southern extremity
of the island, on an alluvial tongue of land, that has been ap-
pended to the primitive rocks, where no doubt the land origi-
nally terminated. This appendage is several miles in length,
and points directly into one of the mouths of the Oronoko, on
the mainland, about twelve or fifteen miles off.

We landed nearly opposite to where we were told we should
find the mud volcanoes, and after making our way about five
miles through the woods, across the sandy isthmus, we came
upon two plantations very pleasantly situated, amidst a group

of

94 ACCOUNT OF THE MUD VOLCANOES IN TRINIDAD,

of remarkable round little hills, each from eighty to a hundred
feet in height. Our path on leaving these led us through
some very thick wood of tall trees, till we found ourselves
again upon a pretty steep regular ascent, which had nothing
remarkable in it, except the diminishing height of the trees as
we went up. Only the tops of these trees, which were of the
kind that usually grow near lagoons and salt marshes, at Jast
appeared above the ground, as we opened a perfectly uniform
round bare platform, of several acres, with different chimneys
in the shape of truncated cones, the highest of them not ex-
ceeding three feet, some of which were throwing out, with a
strong bubbling noise, salt water, about as salt as that of the
Gulf of Paria, loaded, as much as it could be, to preserve its
fluidity, with argillaceous earth. In some of the chimneys this
went on slowly, or not at all; in others it might be called a
pretty active cold ebullition. The surface of the platform
round the chimneys was perfectly firm, and one of our party
picked up a white sea shell, of the turbinated kind, in the act
of being thrown out along with the mud.

We afterwards procured various pyritic fragments that had
been picked up in a similar manner ; but the inhabitants of the.
quarter assured us, that the ebullition, even during its greatest
activity, was quite cold. The smooth circular platform of the
chimneys was bounded by a perfectly regular parapet of clay,
about three feet in height, propped up, as it were, by the tops
of the trees, that, like shrubs, were shooting out of the ground
immediately behind it. This appearance was most likely to
be referred to the buried trees around having had time to
shoot out in the interval between the two last great eruptions,
which take place only during the hottest months of dry sea-
sons, and then the noise is described to be like the loudest
cannon, the mud being thrown up to the height of at least

thirty

ACCOUNT OF THE MUD VOLCANOES IN TRINIDAD. 95

thirty feet in the air, and the theatre of the eruption being
unapproachable within fifty paces.

Close to the first volcano, but in a much more low and sunk
situation, is another of precisely the same appearance and cha-
racter, with only a narrow ravine between the two.

Such an extraordinary phenomenon induced us to exa-
mine the neighbouring mounts of the cleared country, close
to the nearest of which stands the residence of Mon-
sieur CHaNnce.ier, a French planter, and we found them
all, (bating only the eruption) to possess the same form and
composition in all respects as those we had just quitted. The
platform and parapet were easily distinguishable, the chimneys
only were gone, but small pits were left in their places, filled
. with mud, from which air-bells rose even under our own ob-
servation, and our conductor, the intelligent manager of the
estate, told us, that when these rose in salt-water, a fresh erup-
tion was to be apprehended. He pointed out the former site
of his master’s residence, half-way up the mount, which had
been destroyed by one of these eruptions, after a period of
cessation so long, that no record remained of the one that had
preceded it, and he assured us, that during the period he had
lived there (fourteen years) the largest mount now in activity
had gained a very considerable increase of height. s

I have been thus particular in detailing (though at most 1-
relevant length, in a military report) this curious phzenome-
non, from a belief that. it has not been treated of by any
author, and that, when investigated by scientific men, new
light may be thrown on the original formation of argillaceous
hills in situations where it might otherwise be difficult to ac-
count for their appearance.

The magnificent isolated mountain of Tamanaa, in the centre
of the great eastern marsh, unconnected with any chain of
hills, and at an immense distance, on every side, from what

may

96 ACCOUNT OF THE MUD VOLCANOES IN TRINIDAD.

may be called terra firma, may be supposed, till examined,
to have arisen from the plain, through the means of some si-
milar elaboratory in the works of nature. I have said, till exa-
mined,—for its approaches are so barred by the thickest woods,
and deepest swamps, where the boa*, the alligator, and all
the venomous reptiles of the parent continent, still retain the
sovereignty of the soil, that the most determined and enterpri-
sing have never yet been able to penetrate to its base.

* Even the rattlesnake, we were assured, was found here, one having been kill-
ed on the banks of the Guanapo the day before we visited it. The no Jess venomous
mapapi (lance du fer of the French) more formidable on account of his irritable
nature, and greater size (one was killed in the Napoareme eleven feet long), comes
occasionally into the cultivated country, as well as the smaller poisonous coral
snake and others. I have not heard that the dangerous viper of St Lucia and
Martinique has been seen in Trinidad; but the abundance of the boa and alliga-
tor was manifested to a degree that could not otherwise have been believed, when
the great savanah of the eastern marsh, and the underwood of the grand lagoon,
were fired during a very dry season several years ago. This brought all to light
from their different hiding places, and the dead carcases, as marked by the hover-
ing of the vulture and carrion crow, were so numerous, that the air was infected
for miles with the stench

ee

V. Memoir on the Repeating Reflecting Circle. By Major-
General Sir Tuomas Briszane, F. R. 8. E. Corresponding
Member of the Academy of Sciences.

(Read Feb. 15. 1819.)

j = rae had frequent opportunities, during my residence in
France, of seeing a great many Repeating Reflecting Cir-
cles, several of which I have observed with, and having found
much consistency in the results deduced from observations
made with them, it occurred to me, that if I could engage Mr
Troucuton to execute one for me, it would be a most perfect
instrument. This he accordingly did; and F trust that the
observations made with it, which I am about to communicate,
will perfectly justify the opinion I had formed of its precision.
The instrument is only of about six inches radius, divided in
gold to 20”. I have always been in the habit of choosing for
latitudes 30 repetitions, when the weather would permit, divi-
ded into three series of 10 each, and reading the angle or arc
run through during the series, which completely destroys every
imperfection of the division, or reading. In order to deter-
mine the time, I have always found six repetitions quite suffi-
cient to give it as correct as equal altitudes. Of these I also
generally observe three series, in order to take the mean.
These observations I have repeatedly verified by equal alti-

VOL. IX. P. I. N tudes,

98 ON THE REPEATING REFLECTING CIRCLE,

tudes, and found the results the same. I have also ascertain-
ed the accuracy of the instrument from latitudes determined
by a sixteen inch repeating circle with a moveable axis, and
level of RercHennacn’s, with which I had frequently observed
at Valenciennes, Blandecques, &c. ; and it is but justice to
say, that in these instances, Mr Troveuron’s circle gave the
same results to a second. I beg to be permitted tobe a little
more particular than I otherwise should, as to the mode I have
pursued in calculating and deducing latitudes from this instru-
ment, as it is not by any means as-yet generally known in
England, although I -have no doubt, that when quite under-
stood, it will be found to surpass all other instruments of its
size, for simplicity and accuracy, and I am desirous that
amateurs may profit from the experience I have had for some
years of its advantages.

In order to determine the apparent time by the clock or
chronometer, I generally begin two, three, or four hours be-
fore noon, to take the three series of repetitions, and from the
observed angles I infer the time, as pointed out in my former
memoir on the sextant. If the altitudes corresponding to
these can be obtained in the afternoon, I prefer equal altitudes,
or otherwise the simple repetitions made both before and af-
ter noon combined, and the mean taken.

I generally begin to repeat about 77’ before the sun’s passage
over the meridian, which leaves ample time for the three se-
ries, the middle one of which I generally contrive to be divid-
ed by noon, by which means the errors are compensated,
should any exist in the determination of the time, or in the
reductions.

The third series is also finished about the 7’ past noon ; and,
although it is not what I would recommend except in extreme
cases, I have been induced to begin 20’ before noon, and, pro-

vided

ON THE REPEATING REFLECTING CIRCLE. 99

vided I compared that repetition with one made at nearly the
same distance past noon, I have found the mean perfectly
agree with the truth ; although, taken separately, neither would
have been considered as good observations.

It now remains for me to point out the most accurate mode
of inferring the latitude from these different series of repeti-
tions. The most extensive Tables for these reductions are
given by the Baron pr Zacu. M. Bror has also given a very
valuable Table for this purpose.

Type of the most simple and most accurate mode for determin-
ing latitudes by the Repeating Reflecting -Circle.

1, Determine the angle from the arc run through during a
series of repetitions which must always consist of equal
numbers, divided by double the number of repeti-
tions.

The angle being a reflected one, determine by subtrac-
tion each horary angle, and the corresponding quantity
of correction, by M. pz Zacu’s Tables, in his work, Ai-
traction des Montagnes.

2. Determine the apparent altitude and zenith distance.
3. Determine the refraction diminished by parallax.
4. Form for each series the sum of the horary angles. This

sum is composed sometimes of the difference of the
sums before and after noon.

- To form the sum of the quantities corresponding to the
horary angle, from the Tables, which is always the sum,
and never the difference.

6. When there are several different series of repetitions of
ten to calculate together, they become then but as one
series, viz. of 20, 30, or 40 observations; therefore

n2 there

oO

100 ON THE REPEATING REFLECTING CIRCLE.

there is nothing else to be attended to than observing
the rules stated in articles 4 and 5.

7. Calculate the variation in declination for the quantity
corresponding to the sums No. 4. This may either be
done simply by proportions, worked by logarithms, or
taken from Tables calculated for the purpose.

8. Form the apparent declination which will be equal to the
true declination + (the refraction — parallax) + the
variation in declination for the difference of meri-
dians, + the variation of declination for the middle of
the series that you propose to calculate. If the series
is composed of 10, 20, 30, or 40 observations, the re-
sult will be the ;4th, 7,th, ;th, or {jth of the quan-
tity indicated by the sum No. 4. The sign + is appli-
ed when these quantities augment the declination, and
the sign — when they diminish it.

9. Prepare the constant factor

__ Cosine apparent declination. Cosine latitude
. Sine apparent zenith distance

10. Add the logarithm of the constant factor to the loga-
rithm of the sum No. 5., which gives the logarithm of
the meridian correction.

11. Subtract the correction from the apparent zenith dis-
tance.

12. To the result of No. 11. add or subtract the apparent
declination (No. 8.) which gives the distance from the
zenith to the equator, or the Latitude of the place of
observation.

It is almost unnecessary to add, that my artificial horizon
has always been quicksilver, (when the situation would permit
me to us it), covered with one of Troventon’s glass roofs, as I

have

ON THE REPEATING REFLECTING CIRCLE. 101

have pointed out in my former communication to the Society,
on ascertaining time. I have also invariably observed alternate-
ly the upper and lower limb of the sun during the repetitions,
both for the time and latitude; by which means the true alti-
tude of the centre is obtained, independent of the application
of the semidiameter.

Two examples completely worked out accompany this me-
moir, which it is hoped will render it clear and explicit.

In the communication I had the honour to submit to the
Royal Society of Edinburgh on the subject of ascertaining time
with accuracy, and which was read on the 2d February 1818, I
intimated my intention, if that was deemed worthy of a
place in the Transactions, to transmit a memoir on the repeat-
ing circle, which I now beg leave to lay before them, as I feel
confident that the more practical astronomers work with that in-
strument, so as to understand it perfectly, the more they will
be satisfied with the results obtained from it, which I have al-
most uniformly found to be highly satisfactory. Even a small
one of five inches radius, executed for me at Paris by Messrs
Jaxers, has afforded me additional proofs of the value of this
instrument, and the justness of its principle.

There are one or two remarks that I should wish to make
on the subject of the adjustments of the instrument, which I
have learnt from some years constant practice in observing
with it, and which I think may not be deemed unworthy of
detailing.

Although the general nature and principle of the adjust-
ments are similar to those of the sextant, there are others
which differ. In the first place, in order to ascertain whether
the great and small mirrors are parallel, I place the index at
zero ©, and then bring the sun seen direct and reflected in

contact,

[02 ON THE REPEATING REFLECTING CIRCLE.

contact, which I remark. I then move forward the index 90°,.
and thus I repeat the operation successively through each qua-
drant of the 720°. Should they appear quite coincident during
the whole revolution, it is a proof not only that the two mirrors
are parallel, but that the plane of the circle is a true one,
which rarely happens. Should I, however, find, that the reflec-
ted sun appears sometimes to the right and sometimes to the
left of the one seen direct during this operation, it leads me to
suspect that one of two causes of error exists; either that the
plane of the circle is not just, or that the two mirrors are not
parallel. This important point I determine, by examining the
adjustment of the great mirror, which, if found correct, I then
ascribe to the inaccuracy of the plane of the instrument,
which deviation I distribute equally throughout the whole
circle.

The next principal adjustment, is to ascertain if the tele-
scope be parallel to the plane of the circle, which is done ei-
ther by a small proof telescope applied to the circle, when in a
horizontal position; and, if the object seen at some distance
appear in the centre of that telescope, and the one attached to
the circle, it is a~proof of its correctness. There are generally
two small sights sent with the circle, to ascertain this adjust-
ment.

Having carefully examined these, and corrected any error,
if it exists, before each day’s observations, we may rest assured
that the results will be satisfactory, if no error be committed
in determining the time of apparent noon, the observations
properly noted, and the calculations rigorously made ‘according
to the accompanying formule.

Paris, 25th March 1819.

VL

CALCULATION FOR FINDING THE LATITUDE FROM OBSERVATIONS MADE NEAR NOON WITH THE

REPEATING REFLECTING CIRCLE.

Troventon’s Circle.

11 49 36.9 Noon by Chronometer. Instrument at 280° 40’ 00"
11 38 23.3 11 13.6 247.57
88 55.3 10 41.6 224.48
39 25.5 10 11.4 2038.85
89 47.0 9 49.9 189.77
40 14.6 9 22.3 172.42
40 37.3 8 59.6 158.78
41 83 8 28.6 141.07
41 26.7 8 10.2 131.05
41 52.7 T 44.2 117.51
41 17.3 7 19.6 105.39 Ist reading 22° 42’ 15’
92 01.0 1691.89 — 1691.89
+ 250.26
11 49 36.9 1942,15 4th or 1st compound series.
= 211.86
11 44 13.3 5 23.6 5711
44 38.3 4 58.6 48.62 2154.01 = 5, or 2d compound series.
45 13.3 4 23.6 37.89
45 35.0 4 01.9 $1.91
46 5.0 3 31.6 24.42
46 20.3 3 16.6 21.08
47 4.0 2 (32:9 12.74
47 30.0 2 06.9 8.79
48 1.5 1 35.4 4.96
48 26.0 1 10.9 274 2d reading 485° 14 25”
33 02.0 250.26
11 49 36.9
11 50 36.0 1 02.1 2.11
5l 43 1 27.4 4.16
51 33.3 1 56.4 7.89
51 53.3 2 16.4 10.15
52 19.4 2 42.5 14.40
52 46.3 3 09.4 19.56
53 16.2 3 39.3 26.23
53 36.5 3 59.6 31.32
54 2.7 4 25.8 38.54
55 3.0 5 26.1 58.00 $d reading 227° 45’ 12”
30 05.0 211.86
Sun’s declin. at Noon, 16° 34’ 16” 16" 34 167
Refraction — Parallax, -—- 2 29 — 2 28
Correction of declination, — 8.66 — 3.11
Reduction to Meridian, + 1 52.54 + 16.65
Sun’s declin. corrected, 16 33 56.98 16 32 26.74
Observed Angles, = 280° 40’ 0” 22° 49' 15”
+ 720 * 22 42 15 485 14 25
742 42 15 75)462 23 10
280 40 0

s)462 02 15

Altitudes, = 23 6 67 23 «7 36.5
Zenith distances, - 66 53 53.3 16 52 23.5
Corrected declinations, 16 33 56.98 16 32 26.74
Latitudes, 4 50 19 56.32 50 19 56.76
ssenneeess 200,26
Log. Cos. Sun’s declin. 16° 34! 16” = 9.9815769 9.7866230
0.3638832

Log. Cos. Lat. 5019 57 —-9,8050461 :
Log. 2.3983914

——

Constant factors, - - 9.7866230 ache
Ar. Co. Sines of Z - a 2218976
eae 1_ 66 5853.3 = 0.0363027 Ny 1665
Log. 1691.89 = $.2283722 —_—
—— 16” .65
3.0512978
hy) 1195.4

1’ 52 54

Taste I.

8th November 1817, very clear.

Mean Daily variation sun’s declin. = 22’ 36” Log.

(Vol. LX. to front p. 102. )

Quicksilyer Horizon.

3.132260
92 1 Log. = 3.742018

Log. Ar. Co. 24 hours, = 5.063486

1.937764 = (86’.65

Corr. Ist series 5 = 8.66

Var. declin. 22’36” = 3.182260
83 02 = 3.297104
24 hours = 5.063486

1.4928.50 = (81 11”

—_

Corr. 2d series 7; = 3.11

Yar. declin. 2236" Log, = 3.182260

Therm. 13.4 = 9.9944 bs}
29) 0 5 Log. = 3.256477
Barom. 743.0 = 9.990)
pana (enh) Be 24 Ar. co. Log. = 5.063486
53.9 = 184 1.452223 = (287338
21173 = 181".0 Corr. $d series #5 =
Ee eeit orr. 3d series yy = 2.83
122.9
2'Y".9 Refrac. — Parallax.
Therm. + Barom. 9.9844
Z.Dist.66 — 2.1145 sii} ik
52.5 = 180 =BEas

2.1169 = 130’.9 Refr.

Refraction — Parallax 2/ 2.8

16° 34’ 16”
— 2 28
+ 2.83
+ 1410

16 32 30.13

485° 14’ 25"
+ 720 297 45 12

947 45 12
485 14 25
yn 462 30 47
23 7 32.35
66 52 27.65
16 32 30.13

50 19 57.52

9.7866230
0.0363793
2.3260490

21490513
zs) 141.0

y5)117.76 Sum.

8.1 Paral. Corr. 4th series 5.88, or 1st com-
as pound series,
117.76 Sum A.M.
oo 28.33 P.M.
89.43. difference.

Corr. 5th series #, = 2.98 or 2d compound

series,

16 34/16” 16° 34/1
= 2 28 — 2 2
— 5.88 — 2.98
+ 1 459 + 4176
16 33 11.91 16 32 57.98
280° 40' 0* 280° 40’ 0”
+ 720 485 14 95 + 1440 227 45 12
1205 14 95 1667 45 12
280 49 0 280 40
924 34 25 ry 1887 5 12
23 6 51.62 23 7 52
66 58 8.38 66 52 54.8
16 33 11.91 16 32 57.98
50 19 56.47 50 19 56.82
vee 1 942,15 ere PecCiy it 215401
9,7866250 ' 97866230
i 0,0363429 > 0.0363540
Log. 3.2882828 Log. $.3332477
3.1112487 3.1562247
ts) 1291.9 oh) 1432.9
14.59 476

CALCULATION FOR FINDING THE LATITUDE FROM OBSERVATIONS MADE NEAR NOON WITH THE REPE

TrovueuTon’s CrncLE.

1150! 24.3 Noon by Chronometer.
11 45 35.0 4 49.3 45.65
46 3.3 421.0 37.15
46 35.0 3 49.3 28.67
4t 0.5 3 93.8 92,66
47 33.0 2 513 16.01
47 58.0 2 26.3 11.68
48 29.7 1 54.6 7.16
48 56.0 1 28.3 4.25
49 31.7 0 52.6 ee
5 29.3 i
cba eee —— Ast Repetition [592°1' 5']
26 25.8 175.11 175.11
229.27
ple See 404.38 1st compound series.
11 51 37.5 113.2 Aa 1374.53
59.5 1852
: 52 267 2 Wh 8.17 1778.91 2d compound series.
52 45.5 2 21.2 10.87
63 18.5 2 54.2 16.55
53 48.5 3 24.2 92.74
54 16.5 8 52.2 29.41
54 39.5 415.2 35.52
55 11.5 4 47.2 44.98
55 36.5 5 12.2 53.16
31 37.2 229.27 2d Repetition [806° 38! 40’)
11 50 24.3
1157 65 6 42.2 88.23
57 28.5 YT 42 98.13
57 50.0 1 25.7 108.33
58 8.5 T 44.2 107.61
58 33.7 8 94 © 190.62
58 52.0 8 27.7 ow 140.57
59 13.7 8 49.4 152.94
59 35.7 9 11.4 165.81
59 56.5 9 32.2 178.55
0 20.5 9 56.2 193.84
83 02.6 1374.53. 8d Repetition [20° 49, 247]
Sun’s declination, = = 17°58’ 77 17% 58) 7
Refraction — Parallax, _ 2 14.40 — 2 1430
Correction of declination, — 0 116 at 21)
Reduction to Meridian, + 11.45 14.98
Corrected declination, 17 56° 2.29 1756 9.79
Sun’s declination, Cos. 17°58’ 07’ 9.9782836
Log. Co. Lat. 501957 = 9.8050461 ...... 299.27
Constant Factor, - = 9.7833297 : 9.7833297
Ar. Co. sin. zen. Distances, 0.0320246, - 0.0319667
Log. 175.11 = 2,2433109 : 28603472
2.0586652 21756436
ro [ 1146 ro [ 149.8
a 11.45 14”.98
157° 20’ 26" 592° 01/05”
592 01 05 720 + 306 38 40
20 [434 40 39 yo [484 37 35
Altitudes, Q1 44 1.95 21 43 52.75
Z. Distance, 68 15 58.05 68 16 07.25
Declination, 17 56 2.29 1756 9.79
Latitudes, 50 19 55.76 50 19 57.46

N. B. In the preceding calculations, the Centigrade Thermometer and the Metrical Barometer are employed.

Instrument at [157° 20’ 26"}

‘Taste II.

% 13th November 1817.

Diurn. var. © dec, 16’ 0/.5 = 2.982497

26 25.8 3.800248
Ar. Co. Log, 24 hours, 5.063486
1.346231
ifs (176
Corr. for series Ist, 1.76
17.6 before noon,
21.1 afternoon.
y's [3.5 difference.
Corr. for .17 4th series.
1% 58’ 7” 17° 58’ 07"
— 21430 — 2 1430
at 5.54 + 17
+ 1 29.81 + 13.19
17 56 28,05 17 56 6.06
setensees S463! na ies 404.38
9.7833297 x
0.0319491 oosiores
91381542 2.6067897
2.9534330 2.4211898
vy [ 8981 ¥; [263.9
1/29” 81 137.19
306° 38’ 40” 157° 20 26"

720 + 20 49 24

sy [434 10 44

21 42 32.2
68 17 27.8
17 56 28.065

60 19 58.75

720 + 306 38 40

zs (869 18 14

2) 43 57.35
68 16 04.65
17 56 6.06

50 19 56.59

ATING REFLECTING CIRCLE.

Quicksilver. Horizon.

Thermometer = 11°2 = 9.9980.....9.9980

Barometer T4875 = 9.9933...9,9933
Z. Dist. "68° = 2.1561.......2.156]
16 = 68’ 17’.6 — 64
2.1542 2.1538
Refraction, e 142.6 142.5
Parallax, - - 8.2 8.2
1344 134g
Refraction — Parallax, 2/14"4 2149
2.982497 2.982497
3) 37".2 = 3.278113 83'2/.6 = 3.697456
5.063486 5.063486
1.324096 1.743489
Py (21"1 Py [55".4
2d = 2.11 3d = 5.54
211 ft
554 afternoon.
76.5 sum.

17.6 forenoon.

sp [58.9 difference.

1.96 Corr. for 5th series.

17° 58' 07
— 2143

17 56 33.42

- 1778.91

9.7833297
0.0319969
3.2501539

3,0654805
so [1162.7

38”.76

157 20: 26
1440 + 20 49 94

sy [1307 28 58

17 56 33.42

50 19 57.61

- VI. Description of a Fossil Tree found in a Quarry at Nites-
. hill, the Property of Colonel Duntop of Househill. By
the Rey. Patrick Brewster, one of the Ministers of the

Abbey Church, Paisley.

(Read Feb. 1. 1818.)

Tue quarry of Niteshill, fronr which this very interesting
petrifaction was taken, lies about three miles south-east of
Paisley, and is part of a coal formation. It consists of white
sandstone, which in many parts is deeply stained by an im-
pregnation of iron. Two very thin seams of excellent coal oc-
cur immediately under the sandstone, with the intervention
of a few feet of till or blaize. The strata dip to the south, and
crop out about a hundred yards north of the spot from whence
the tree was taken. At this-spot the face of rock is about six-
teen feet ; fourteen feet above the tree, and one under ; ano-
ther foot being occupied by the stem itself.

The part which has been detached from the rock consists
of stem and roots, five feet of stem, and.two of roots, different
views of which I have endeavoured to represent in figures 1,
2, & 3.

The tree was found in contact on every side with the solid
rock. Its direction was nearly north and south; the root end

pointing

104 ACCOUNT OF A FOSSIL TREE FOUND

pointing to the north, and the line of the trunk inclining with
the strata to the south ; the dip being one foot in seven.

When it was first disengaged from the surrounding mass, it
had a complete envelope of coal, incrusting its whole surface :
but this interesting portion had been removed by the work-
men before I had an opportunity of examining it. Deprived
of the coal, the surface still bears a considerable resemblance
to bark.

From the fracture of the stem downwards, the lines or fur-
rows are pretty regular; but as they approach the root, they
meet and run into each other. On one side the space between
them is slightly convex, while on the opposite it is concave,
and somewhat of a fluted appearance.

Internally there cannot be perceived the slightest vestige of
any ligneous structure. The stone of the tree, however, is in
some respects different from that of the circumjacent rock : it
is in general more compact, and contains more iron, and is
of course specifically heavier.

Owing to the impregnation of iron, the colour is in some
parts so much deepened, that the workmen mistook it for
whin. This difference of colour and of gravity, however, is
partial, and does not extend equally through the whole mass
of the petrifaction. In some of the roots particularly, the
stone is as pure as in any part of the quarry.

For the following dimensions I am indebted to Colonel
Dunlop of Househill the proprietor, who, with that kindness
and liberality which distinguishes him, has afforded every faci-
lity towards the examination and description of this singular
fossil.

The trunk, independent of the roots, is five feet in length.
There are four principal roots, each of which measures two

feet.

Pa

— —

aanG nar aase aa

“G07? *t 11

IN A QUARRY AT NITES-HILL. 105

feet. The circumference, taken close by the root, is five feet
seven inches and a half: In the middle of the stem four feet
and a half ; and at the top or fracture three feet nine inches.

In the immediate neighbourhood of the above tree, and in
the same rock, there are four converging branches, which have
once been united ; three of which penetrate the rock in diffe-
rent directions, and the fourth runs along its surface. They
are evidently of a different species, and belong, I suspect, to
the fragment of another stem which was found some time ago
near the same spot. The species to which they belong is well
known among this class of petrifactions, and occurs in some of
the neighbouring quarries. The length of the exposed branch,
from the fracture to the point of division, is 15 inches ; the as-
cending branch is 26 inches, and the other is 35.

Description of the Figures, Pirate IX.

Figs. 1, 2, 3, are different views of that part of the tree
which has been detached from the rock, and which is now
at Househill.

Fig. 4. represents that part of the quarry in which the remain-
der of the tree is still lodged.

Fig. 5. represents four converging branches of a different spe-
cies of tree, found near the former.

Fig. 6. is a section of a trunk found near the above branches,
and supposed of the same species.

VOL. IX. P. 1. 0 VIL.

net

Ws, tea aie 40, pry .

spestoned Hitt sk, syed

VII. Account of a non-descript Worm (the Ascaris pellucidus )
found in the Eyes of Horses in India. In Letters from
ALEXANDER Kennepy, M. D. F.R.S. Eprn. fo Profes-
sor Russetn and Dr Horr. With a Description of the
Animal, by Captain Tuomas Brown, F. R.S. E. &
F.L.S.

(Read Feb. 5. 1816, and Nov. 9. 1818.)

Dear Sir, Edinburgh, 5th February 1816.

W uen I lately mentioned to you in conversation, the dis-
ease in the eyes of horses in India, occasioned by the presence
of a worm within the ball: of the eye, I thought that you
might probably have heard of it before; but as you had not,
and are desirous of further information upon the subject, I now
take this method of mentioning the circumstances to you, so
far as I know them.

The animal occasioning this disease, is termed ie the na-
tives about Madras, the “ Worm” in the Horse’s Eye, by using
the corresponding words in their respective languages. I have
been told that in Bengal it is called the “ Sanp,” or the Snake
in the Horse’s Eye. As it seems more to resemble a fish or
an aquatic insect, it might perhaps with more propriety be re-
garded as an eel.

02 This

108 ACCOUNT OF A NON-DESCRIPT WORM

This disease often follows blows or external injuries; but
also frequently occurs without this previous cause. After
weakness, watering, and inflammation of the horse’s eye, it as-
sumes a whitish look, and then the worm may be plainly ob-
served, of a white colour, swimming with great briskness and
activity through the aqueous humour. The cure depends up-
on its being extracted, without which, I believe, that the eye
is always lost by suppuration. I have known several medical
gentlemen attain much dexterity in performing this extrac-
tion. The mode of proceeding is as follows: Being provided
with a common lancet, armed at the shoulders by being wrap-
ped round with tow, the operator places himself by the horse’s
head, next to the diseased eye, and moving his hand gently
up, so as not to alarm the horse, he thus watches the opportu-
nity of the eye’s being well open, and then suddenly plunges
the lancet through the lower and fore part of the cornea, di-
recting the point across, and at the same time cutting down-
wards. The aqueous humour being in this manner suddenly
evacuated, by a gush, or in a stream, the worm passes out
along with it. The eye is then covered up, and kept wetted
with a cooling solution. When the extraction has been suc-
cessfully performed, and the aqueous humour is again resto-
red, the vision is found unimpaired.

The fineness and small size of the worm sometimes prevent
its being found, even when the extraction has been successful-
ly performed. It is frequently detected, however, in the track
of the aqueous humour over the horse’s face. When picked
up, it generally appears to be dead, at least I have met with
none which retained any appearance of life. I have seen none
of them so long as the nail of the thumb. It is of a grey-
white colour, very soon lies flat and flaccid, and appears to be
not much broader or thicker than a horse’s hair. My friend

Dr

FOUND IN THE EYES OF HORSES IN INDIA. 109

Dr Berry, however, who has frequently succeeded in extract-
ing them, informs me that he has not only often met with
them considerably longer than I have described, but also that
upon his placing them in a tumbler of tepid water, he has seen
them swim about for several minutes, and even for a quarter
of an hour; and that when viewed in this situation, the shape
evidently appears to taper off towards the tail. Had I thought
of placing those which I have met with, as Dr Berry did, in
tepid water, it seems not improbable, that I might both have
found some of them alive, and also of greater length, than
when viewed under exposure to the open air.

Upon this occasion, it is both proper and satisfactory to re-
fer to the testimony of that eminent naturalist, the late Dr
James Awnperson of Madras. Having had occasion, several
years ago, to mention this worm, and the disease which it oc-
casioned in the horse’s eye, to one of his scientific correspon-
dents, it is believed to Dr Rusu of Philadelphia, his letter was
at the time given to the public, in one of the Madras newspa-
pers. Though Dr AnpErson’s correspondence was afterwards
collected from the newspapers, and reprinted, it might now be
difficult to find a copy of it. But I recollect to have heard af-
terwards, that the letter now alluded to, had been communica-
ted by Dr AnpErson’s correspondent to the American Philo-
sophical Society. I remain, &c.

Atzex. Kennepy.

To James Russell, Esq.

Dear

110 ACCOUNT OF A NON-DESCRIPT WORM

Dear Sir, Edin. \7th Nov. 1819.

Fixpine that my last communication, regarding the worm
in the eyes of horses in India, submitted to the Royal Society
by Mr Russetz, has been mislaid, I shall now do what in me
lies, to replace that loss, in the most satisfactory manner I can,
from memory.

Immediately after my letter upon this subject to Mr Rus-
SELL, under date 5th February 1816, I applied to several of
my friends in India for a specimen of the worm; and the pa-
pers now amissing, consisted of a short letter from myself to
Mr Russet, covering the original letter from Mr Witi1am
Scor, Surgeon of one of the battalions of Madras artillery,
along with which he had sent home one of the worms, extract-
ed by himself, and which was presented to the Royal Society
at the time his letter was read.

I now regret not having preserved a copy of that letter, but
am willing to believe, that in the following recapitulation of
its contents, there can be no material error.

The worm was discovered in the eye of a horse belonging
to Lieutenant-Colonel Freesr at St Thomas’s Mount, on the
5th of May 1818, and was extracted next day by Mr Scor, in
presence of Colonel Freese, Dr M. S. Moorg, and a third per-
son, whose name I do not now recollect. Mr Scor’s letter was
dated 7th May. In it he described the appearance of the eye,
much as I had done, in my letter to Mr Russetx, and noticed
its milky appearance, and the lively motion of the animal in
the aqueous humour, comparing the mode of its progress to
something resembling leaping, which it seems to me might be
no inapt comparison, when the worm was fore-shortened, by
moving nearly in the line of vision of the spectator.

In this instance, it was found necessary to throw down the
horse, an attempt to operate while he was standing having
failed. The worm was received among tepid water, in a

China

FOUND IN THE EYES OF HORSES IN INDIA. 111

China saucer, where it continued to move about briskly, until
a little cold water was added, when it fell dead instantly, and
was afterwards with difficulty detected at the bottom of the
vessel.

This may be the most proper place to mention, that I have
lately received three more of these worms from Mr Scor,
which were extracted by Mr Berrincr, who keeps a livery
stable at Madras. Having presented two of these to the Uni-
versity Museum, they are now in the custody of Professor Ja-
MESON. I have the honour to remain, &c.

ALEX. KENNEDY.

To Dr T. C. Hope, F. BR. S. E. &c.

Ascaris pellucidus.—Head slightly subulate, with the extre-
mity somewhat obtuse; body smooth, pellucid, of a blu-
ish-white colour; thickest at the centre, and gradually
tapering towards the head, and abruptly towards the tail,
which terminates in a sharp point; its diameter not being
more than a fourth of the head. Length an inch and a
quarter.

Inhabits the aqueous humour of the eyes of horses in India ;
in which it may be seen swimming about with great activity.
Is said to be generally produced by external injuries; though
in some instances it has occurred without any known cause.

VIIL

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Dee I

VIII. Memoir relating to the Naval Tactics of the late JOHN
CLERK, Esq. of Eldin; being a Fragment of an intend-
ed Account of his Life. By Joun Puayrar, F.R. S.
Lonp. & Eni. Professor of Natural Philosophy in the
University of Edinburgh.

(Read April 6. 1818.)

* * © * KF KK KF KH K

Tue author of the Naval Tactics is one of those men who,
by the force of their own genius, have carried great improve-
ments into professions which were not properly their own.
The history both of the sciences and of the arts furnishes seve-
ral remarkable examples of a similar nature. Frrmat the rival,
sometimes the superior of Descartes, one of the most inven-
tive mathematicians of a most inventive age, was by profes-
sion a lawyer, and had only devoted to science the time that
could be spared from the duties of a counsellor or a judge:
about fifty years earlier, also, his countryman Viera had made
a like digression from the same employment, and hardly with
inferior success.

Prrravtt, who, in the facade of the Louvre, has left behind
him so splendid a monument of architectural skill and taste,
was a physician, and not only practised, but wrote books on
medicine. Dr Herscnett too, who has made more astrono-

VOL, IX. P. I. P mical

114 FRAGMENT OF AN INTENDED ACCOUNT

mical discoveries than any individual of the present age, be-
took himself to the study of the heavens as a relaxation from
professional pursuits. Mr Crerx is to be numbered with these
illustrious men, having made great improvements in an art to
which he was not educated, and in which early instruction, and
long practice, would seem more indispensable than in any
other. :

Two reasons may perhaps be assigned for the success which
often attends men who thus take a science by assault, without
making their approaches regularly, and according to the rules
of art. They are inspired by genius, and impelled by the
highest of all motives, the pleasure they derive from their ex-
ertions. They are also free from the prejudices, and the blind
respect for authority, which constitute so strong a barrier
against improvement both in the sciences and the arts.

A young man, who had been bred in the service of the Na-
vy, who had seen the Commanders he was taught to respect
most highly, bring their fleets into action constantly in a cer-
tain way, and who had naturally made that manceuvre the
great object of his study, would not be apt to deviate from a
practice, in the accurate and successful application of which
the greatest merit of a Naval Officer was supposed to consist.
Indeed no man learns his art, as it actually exists, more com-
pletely than a seaman ; but no man learns it in a way more
likely to preclude improvement. A landsman, therefore, sit-
ting in his study, and thinking only of the abstract principles,
mechanical or tactical, of the naval art, provided he be well in-
structed in them, and have a mind sufficiently powerful to
combine those principles, and appreciate their different re-
sults, may be expected to give valuable lessons to the most
able and experienced seamen.

Mr

OF THE LATE JOHN CLERK, ESQ. OF ELDIN. 115

Mr Cuerx was precisely the man by whom a successful
inroad into a foreign territory was likely to be made. He pos-
sessed a strong and inventive mind, to which the love of know-
ledge, and the pleasure derived from. the acquisition of it, were
always sufficient motives for application. He had naturally no
great respect for authority, or for opinions, either speculative
or practical, which rested only on fashion or custom. He had
never circumscribed his studies, by the circle of things imme-
diately useful to himself; and I may say of him, that he was
more guided in his pursuits, by the inclinations and capacities
of his own mind, and less by circumstance and situation, than
any man I have ever known. Thus it was, that he studied
the surface of the land as if he had been a general, and the
surface of the sea as an admiral, though he had no direct con-
nection with the profession either of the one or of the other.

From his early youth, a fortunate instinct seems to have
directed his mind to naval affairs. It is always interesting to
remark the small and almost invisible causes from which ge-
nius receives its first impulses, and often its most durable im-
pressions. “ I had (says he) acquired a strong passion for nau-
“ tical affairs when a mere child. At ten years old, before I
“ had seen a ship, or even the sea at a less distance than four
“ or five miles, I formed an acquaintance at school: with
“ some boys who had come from a distant sea-port, who in-
“ structed me in the different parts of a ship from a model
“ which they had procured. I had afterwards frequent oppor-
“ tunities of seeing and examining ships, at the neighbouring
“ port of Leith, which increased my passion for the subject ;
“ and I was soon in possession of a number of models, many _
“« of them of my own construction, which I used to sail on a
“ piece of water in my father’s pleasure-grounds, where there

p2 “ was

116 FRAGMENT OF AN INTENDED ACCOUNT

“ was also a boat with sails, which furnished me with much
“ employment. I had studied Robinson Crusoe, and I read
“* all the sea-voyages I could procure.”

The desire of going to sea, which could not but arise out of
these exercises, was forced to yield to family considerations ;
but, fortunately for his country, the propensity to naval affairs,
and the pleasure derived from the study of them, were not
to be overcome.

He had indeed prosecuted the study so far, and had become
so well acquainted with naval affairs, that, as he tells us him-
self, he had begun to study the difficult problem of the way of
a ship to windward. This was about the year 1770, when an
ingenious and intelligent gentleman, the late Commissioner Ep-
car, came to reside in the neighbourhood of Mr Cirrx’s seat
in the country. Mr Evear had served in the army, and, with
the company under his command, had been put on board Ad-
miral Byne’s ship at Gibraltar, in order to supply the want of
marines ; so that he was present in the action off the Island of
Minorca, on the 20th of May 1756. As the friend of Admi-
ral Boscawen, he afterwards accompanied that gallant officer
in the more fortunate engagement of Lagos Bay.

After the American war was begun, an attention to the
narratives of his friend, and still more to the actions which were
then happening at sea, served to convince Mr Cierx that there
was something very erroneous in the methods hitherto pursued
by the British admirals for bringing their fleets into action ; in-
somuch, that, though nothing could exceed the skill with which
each individual ship was worked, yet when one whole fleet was
opposed to another, the plan followed was uncertain and preca-
rious, and it seemed that the expedient for forcing an enemy to
fight, remained yet to be discovered. It appeared, indeed, that

very

ee

OF THE LATE JOHN CLERK, ESQ. OF ELDIN. 117

very little attention had yet been paid to the subject of Naval
Tactics.

The oldest work we know of that treats of Naval Tac-
tics, is that of the learned Jesuit Perr Hoste, Professor of
Mathematics in the Royal College at Toulon, and entitled
L) Art des Armées Navales. It is an elementary and distinct
exposition of the ordinary manceuvres at sea, and has no pre-
tensions to any thing more. It was, however, highly regard-
ed at the time: the author, when he presented it to Louis the
XIV.. in 1697, was well received, and had a pension given
him.

There was no book on the subject in the English language ;
and the conduct of our sea-fights, though it had so often pro-
ved successful, did not display much extent or variety of re-
sources. It had usually happened that the British fleet was
eager to engage, and that the enemy was unwilling to risk a
general action ; our object, therefore, had almost always been
to gain the weather-gage, as it is called, of the enemy, or to
place ourselves to windward of his fleet. When that fleet was
drawn out in line, in the manner necessary for allowing every
ship its share in the action, the British fleet bore down from
the windward on the enemy, lying to as it is termed, or almost
fixed in its position ; the whole line, and also the broadside of
each individual ship, being nearly at right angles to the direc-
tion of the wind.

Under these circumstances, the British fleet had usually
pursued one of two methods of making the attack. The one
consisted in forming a line parallel and directly opposite to
that of the enemy; after which each ship bore down on that
which was immediately opposed to it. According to the
other method, the British fleet, on the opposite tack to that of
the enemy, ran along parallel to it, and within fighting dis-

tance,

718 FRAGMENT OF AN INTENDED ACCOUNT

tance, till the whole of the one line was abreast of the other,
and each ship ready to engage her antagonist.

If the first of these methods was pursued, each ship, on co-
ming down, had a very sharp fire to sustain from the broad-
side of that opposed to her, which she could only return fee-
bly from the guns on her bow. The rigging, of consequence,
which presented the best mark when seen endwise, was likely
to be so much cut, that the ship must be nearly disabled be-
fore she arrived at the fighting distance.

If the second method was pursued, the headmost ship had
to endure the fire of the whole line before it arrived in its
place ; the second, the fire of all but one ; the third, of all but
two, and soon: so that it was not likely that any but the
sternmost ships could reach their station without having re-
ceived considerable damage. This gave to the enemy, who
quietly remained on the defensive, a great advantage over the
attacking squadron, and enabled him, almost to a certainty, to
come off, if not with victory, at least with very little loss.

The disadvantages, however, arising from these two modes
of attack, either had not been duly considered, or had been
set down among the unavoidable evils necessarily involved in
a determination to force the enemy to fight. Perhaps, too,
the desire of complying literally with the instructions always
given to our admirals, of doing their utmost to take, burn, and
destroy, contributed to make it be thought, that a direct and
immediate attack, such as has just now been described, was
the only means that could properly be resorted to,

Mr Crzrx had the merit of pointing out the evils now enume-
rated, in a manner most clear and demonstrative, and of describ-
ing a method by which the attack might be made, without incur-
ring any of the disadvantages that have been mentioned, and

almost

OF THE LATE JOHN CLERK, ESQ. OF ELDIN. 119

almost with a certainty of success. As the evil arose from an
endeavour to diffuse the force of the attack, if one may say so,
over the whole surface of the line attacked; so the remedy
consisted in concentrating the force of the attack, and in bring-
ing it to bear with proportionally greater energy on a single
point, or a small portion of the enemy’s line. For this pur-
pose the admiral of the attacking and windward squadron,
is supposed to come down, not in line, but with his fleet in di-
visions, so as to be able to support the particular division de-
stined to break through the line of the enemy. The conse-
quence must be, that, if this attack is directed against the rear
of the enemy, the ships a-head must either abandon those that
‘are cut off, or must double back, either by tacking or wearing.
Here Mr Cuerx shews, that if the enemy follow the first of
these methods, and make his line either tack in succession, or
altogether, such a distance must be left between them and the
three or four sternmost ships, that not only must those last be
easily carried, but that several more must probably be thrown
into such a situation as to subject them almost unavoidably to
the same fate. Ifthe enemy attempt the same thing by wear-
ing, his condition will be still worse. The fleet, by falling to
leeward, must not only desert the ships attacked altogether,

but must leave the sternmost of the wearing ships so much
exposed as to render it certain that they will be entirely cut
off.

At the time when this method of attack was proposed, it
was regarded as a manceuvre quite new, and as having never
yet been acted on. Mr Cenk, indeed, has entered into a hi-
storical detail, which tends to establish this point, and in
which, from the most authentic documents, he traces the plans
of most of our remarkable naval actions, from that of Admiral
MarttueEws, off Toulon, in 1744, to that of Admiral Greaves

off

120 FRAGMENT OF AN INTENDED ACCOUNT

off the Cheasapeak in 1781. In most of these actions, though |
conducted by some of our ablest naval officers, the British fleet
being to windward, by extending the line of battle, with a de-
sign of disabling or destroying the whole of the enemy’s line
to leeward, was itself disabled before the ships could reach a
situation in which they could annoy the enemy ; while, on the
other hand, the French, perceiving the British ships in disor-
der, have made sail, and, after throwing in their whole fire,
have formed a line to leeward, where they lay prepared for
another attack ; and thus has been frustrated that combination
of skill and courage which distinguishes our seamen, and has
always been so conspicuous in actions of single ships. The
analysis of those actions forms a most interesting part of Mr
Cierx’s book, and furnishes a commentary on the naval histo-
ry of Britain, such as we seek for in vain in the treatises writ-
ten expressly on that subject.

In the second part of his work, which, though first written,
was last published, the author has considered the nature of the
attack from the leeward, or where the fleet which would force
the other to action has not the advantage of the weather-gage.
Here also he proves, by arguments very clear and convincing,
that nothing promises success but the cutting of the enemy’s
line in two; the leeward fleet on the opposite tack to that of
the enemy, bearing up obliquely, so as to pierce the line in
the centre, or towards the rear, as circumstances may direct.
The ships thus cut off could have no support, and must either
save themselves by downright flight, or fall into the hands of
the enemy.

The time when Mr Crerx was engaged in these specula-
tions, was a period very memorable in the naval, the military,
and political history of this country; and never was there a
moment when the communication of the secret he had disco-

vered

OF THE LATE JOHN CLERK, ESQ. OF ELDIN. 121

vered could have been attended with more important conse-
quences. The contest in which Britain was engaged with the
American colonies, so questionable in its principle,—so appro-
ved by the nation,—and so obstinately pursued by the Go-
vernment, had involved the country in the greatest difficul-
ties. A series of great and ill-directed efforts, if they had not
exhausted, had so far impaired, the strength and resources of
Britain, that neighbouring nations thought they had found a fa-
vourable opportunity for breaking the power, and humbling the
pride, of a formidable rival. The French Government, desi-
rous of accomplishing an object of which it had never lost
sight, and willing also to share in the glory of giving inde-
pendence to a new State, was yet ignorant of the lesson which
it was so soon to learn to its cost,—the danger which a despot
runs, who attempts to give that liberty to other nations which
he refuses to his own people. Spain also, which we see at this
moment exerting every nerve to continue the thraldrom of
her own colonies, joined eagerly in the scheme of giving inde-
pendence to those of England ; and by her detail of a hundred
grievances, sufficiently convinced the world, that her hostility
to Britain proceeded from a cause which she could not venture
to avow.—Against this formidable combination, which Hol-
land was preparing to join, Britain stood alone without an al-
ly; and not merely alone, but divided in her counsels, with
more than half her force engaged in the operations of a de-
structive civil war, in which victory would have been more
ruinous than defeat. These were circumstances, which, in the
mind of every friend to his country, could not but excite
anxiety and alarm ; yet they were perhaps not the most threa-
tening that distinguished this perilous crisis. In the naval
rencounters which took place after France had joined herself
to America, the superiority of the British navy seemed almost

VOL. IX. P. I. Q to

122 FRAGMENT OF AN INTENDED ACCOUNT

to disappear ; the naval armies of our enemies were every day
gaining strength; the number and force of their ships were
augmenting; the skill and experience of their seamen appear-
ed to be coming nearer to an equality with our own. Their
commanders were completely masters of the art of avoiding a
general or decisive action, and atthe same time of materially
injuring their enemies. In the doubtful conflict: off Ushant,
which gave the commencement to our hostilities with France,
the British admiral, after placing himself between the French
fleet and their own coast, continued to manceuvre for several
days together, without being able to bring on a general action,
and was forced at length to draw off towards his own ports,
allowing the French to return to theirs, without the capture of
a single ship to support his own claim to victory, or to refute
that of the enemy. The year which followed this had witnes-
sed the most inglorious naval campaign recorded in the annals
of Great Britain. The combined fleets of France and Spain
were seen riding with exultation in the British Channel, cap-
turing our ships close to our own shores, while the nayal force
of Britain stood aloof, and only ventured to look from a dis-
tance on a scene which every British seaman beheld with
grief and indignation, while he seemed to read in it the tale of
his personal dishonour. Another action in the course of the
same year, had no great tendency to console us for the dis-
graceful caution which our fleet.in the Channel had been for-
ced to observe. Admiral Byron. attempted to bring the
French fleet, off Grenada, to action, and after the greatest
gallantry, displayed both by himself and the officers under his
command, he entirely failed in his object, and even suffered
considerable loss. Indeed when one studies the account of
this action, by help of the light which the author of the Naval
Tactics has thrown on it, he sees with much regret the highest

efforts

OF THE LATE JOHN CLERK, ESQ. OF ELDIN. 123

efforts of valour and seamanship thrown away, from our igno-
rance of the true principle by which our attack should have been
directed ; while the French, in their position to leeward, suc-
ceeded, with their usual address, in damaging our ships, and
in saving their own.

The parallel drawn by Mr Crzrx between the unfortunate
engagement of Admiral Byne and this of Admiral Byron, is
sufficiently striking, and shews but too clearly, that there are
many circumstances, besides conduct and valour, that deter-
mine the character of a soldier that fights either at sea or
land.

The action of Admiral ArsuTunor in the succeeding year,
deceived equally the hopes of the nation, and equally demon-
strated the skill of the French commanders, in the means of
obtaining the end they had in view, and in entirely defeating
that of their enemy ; and by its unhappy influence on our mi-
litary operations on shore, may be regarded-as the most fatal
miscarriage that marked the progress of the British arms.
The action of Admiral Greaves off the Cheasapeak, conclu-
ded a series of unsuccessful attempts, in which, though no
signal disaster fell on the British fleet, no glory was gained,
the ultimate object of the expedition was always lost, and, to a
power used to boast in its superiority, the entire absence of
victory seemed equivalent to defeat. The enemy was acqui-
ring skill and confidence, while we were losing that feeling of
superiority on which success. so often depends. The circum-
stances of the nation had never called on every individual to
think more seriously of the situation of his country ; nothing
had ever proved so clearly, that, at sea, the system of offensive
warfare was yet but imperfectly understood, nor was there
ever a juncture, when such discoveries as Mr Currx had made,
could be brought forward with so great effect. To a man

a2 who,

124 FRAGMENT OF AN INTENDED ACCOUNT

who, like him, was a real lover of his country, sincerely inte-
rested in its liberty and independence, as well as in the glory
of its flag; full also of the enthusiasm of genius, and the love
of science ; I can hardly imagine any higher or more exquisite
delight, than that which he must have felt, when his imagina-
tion arose from the despondency into which the actual state of
things had thrown every thinking man, to consider the change
which the secret which he had in his possession was likely,
nay sure to make, in the condition of his country.

There can exist, I think, but one feeling superior to this,—
that which must arise on seeing this noble vision realized.
This also fell to the share of the author of the Naval Tactics,
who lived to see his measures carried into effect with unex-
ampled skill and gallantry ; saw them lead to victories more
splendid than the most sanguine hopes could have ventured
to anticipate, and saw himself become one of the great instru-
ments by which Providence enabled his country to weather a
more awful tempest than any by which it had hitherto been
assailed.

Being fully satisfied as to the principles of his system, Mr
Crerx had begun to make it known to his friends as early as
1779. After the trial of Admiral Kepprti had brought the
whole proceedings of the affair off Ushant before the public,
Mr Crerx made some strictures on the action, which he put
in writing, illustrating them by drawings and plans, contain-
ing sketches of what might have been attempted, if the attack
had been regulated by other principles, and these he commu-
nicated to several naval officers, and to his friends both in
Edinburgh and London.

In the following year he visited London himself, and had
many conferences with men connected with the navy, among
whom he has mentioned Mr Arxinson, the particular friend of

Sir

OF THE LATE JOHN CLERK, ESQ. OF ELDIN. 125

Sir Georcr Ropney, the Admiral who was now preparing to
take the command of the fleet in the West Indies. A more
direct channel of communication with Admiral Ropnry was
the late Sir Cuartes Dovcuias, who went out several months
after the Admiral, in order to serve as his Captain, and did
actually serve in that capacity in the memorable action of the
12th of April 1782. Sir Cuarves, before leaving Britain, had
many conferences with Mr Cierx on the subject of naval
tactics, and, before he sailed, was in complete possession of
that system. Some of the conferences with Sir CuarLes were
by the appointment of the late Dr Buarr, prebendary of West-
minster ; and at one of these interviews were present Mr Wi1-
uiaM and Mr James Apam, with their nephew the present
Lorp Curer Commissioner for Scotland. Sir Cuarurs had
commanded the Stirling Castle in KEepreti’s engagement ; and
Mr Cierxk now communicated to him the whole of his stric-
tures on that action, with the plans and demonstrations, on
which the manner of the attack from the leeward was fully de-
veloped.

The matter which Sir Cartes seemed most unwilling to
admit, was the advantage of the attack from that quarter ; and
it was indeed the thing most inconsistent with the instructions
given to all admirals.

Lord Ropney himself, however, was more easily convinced ;
and in the action off Martinico, in April 1780, the original
plan seemed regulated by the principles of the Naval Tactics.
The British fleet was to leeward, and the first signal made by
the Admiral gave notice of his intention to attack the enemy’s
rear with his whole force. The enemy, however, having dis-
covered this intention, wore, and formed on the opposite
tack, and thus the effect of the signal was for the time defeat-
ed. The Admiral appeared then to depart from the new sys-

tem ;

196 FRAGMENT OF AN INTENDED ACCOUNT

tem; for the next signal which he threw out, was for every
ship to bear down on her opposite, according to the 21st ar-
ticle of the additional fighting instructions. It appears, as we
shall afterwards see, that the cause of this change was the mis-
take of the signals,.the captains of the fleet not being suffi-
ciently prepared for the new method of attack. In the two
actions which immediately followed this, on the 15th and 18th
of the next month, the French succeeded in the defensive sys-
tem; and it was not till two years afterwards, in April 1782,
that Lord Ropney gave the first example of completely break-
ing through the line of the enemy, and of the signal success
which must ever accompany that manceuvre, wher skilfully
conducted. The circumstances were very remarkable, and
highly to the credit of the gallantry as well as conduct of the
Admiral. The British fleet was to leeward, and its van, on
reaching the centre of the enemy, bore away as usual along
his line; and had the same been done by all the ships that fol-
lowed, the ordinary indecisive result would infallibly have en-
sued. But the Formidable, Lord Ropney’s own ship, kept
close to the wind, and on perceiving an opening near the
centre of the enemy, broke through at the head of the rear di-
vision, so that for the first time the enemy’s line was cut in
two, and all the consequences produced which Mr Crier had
predicted.

This action, which introduced a new system, gave a turn to
our affairs at sea, and delivered the country from that state of
depression into which it had been thrown, not by the defeat
of its fleets, but by their entire want of success.

Tt was in the beginning of this year that the Naval Tactics
appeared in print, though for more than a year before copies
ofthe book had been in circulation among Mr Crerx’s friends.
Immediately on the publication, copies were presented to the

Minister

OF THE LATE JOHN CLERK, ESQ. OF ELDIN. 127

Minister and the First Lorp of the Apmiratty. The Duke
of Montacus, a zealous friend of Mr Cxrerx’s system, under-
took the office of presenting a copy to the Kine.

Lord Ropney, who had done so much:to prove the utility
of this system, in conversation never concealed the obligation
he felt to the author of it. Before going out to take the com-
mand of the fleet in the West Indies, he said one day to Mr
Dowpas, afterwards Lord Metvittr, “ There is one Crzrk, a
“ countryman of yours, who has taught us how to fight, and
““ appears to know more of the matter than any of us. If
“ ever I meet the French fleet, I intend to try his way.”

He held the same language after his return. Lord Met-
VILLE used often to meet him in society, and particularly at
the house of Mr Henry Drummonn, where he talked very un-
reservedly of the Naval Tactics, and of the use he had made
of the-system in his action of the 12th of April. A letter
from General Ross states very particularly .a conversation of
the same kind, at which he was present. “ It is (says the
** General) with an equal degree of pleasure and truth, that I
“ now commit to writing what you heard me say in company
“ at your house, to-wit, that at the table of the late Sir Joun
“ Dauiinc, where I was in the habit of dining often, and
“ meeting Lord Ropney, I heard his Lordship distinctly state,
“ that he owed: his success in the West Indies to the ma-
“ noeuvre of breaking the line, which he learned from Mr
“ Crerx’s book. This honourable and liberal confession of
“ the gallant Admiral, made so deep an impression on me,
“ that I can never forget it; and I am pleased to think, that
“ my recollection of the circumstance may be of the smallest
“ use to a man with whom I am not acquainted, but who, in
my opinion, has deserved so well of his country.”

ral
e

As

128 FRAGMENT OF AN INTENDED ACCOUNT

As a farther evidence of the sentiments of the Admiral on
a subject where they are of so much weight, I have to quote a
very curious and valuable document, a copy of the First Part of
the Naval Tactics, with Notes on the margin by Lord Rop-
ney himself, and communicated by him to the late General
Cuierx, by whom it was deposited in the family library at Peni-
cuik. The notes are full of remarks on the justness of Mr
CiEerxk’s views, and on the instances wherein his own conduct
had been in strict conformity with those views. He replies in
one place to a question which Mr Crerx had put (published
after the action in spring 1780,) of which mention has been
already made, concerning the conduct of that action. The
first signal of the Admiral, as we have already seen, was for
attacking the rear with his whole force. The French, percei-
ving this design, wore, and formed on the opposite tack. This
made it impossible immediately to obey the Admiral’s signal,
and the next that he made was for every ship to attack her
opposite. Mr Crerx’s question was, Why did Sir Grorcr
change his resolution of attacking the rear, and order an at-
tack on the whole line ?—Sir Grorce answers to this, That he
did not change his intention, but that his fleet disobeyed his
signals, and forced him to abandon his plan.

An anecdote which sets a seal on the great and decisive testi-
mony of the Noble Admiral, is worthy of being remembered, and
I am glad to be able to record it on the authority of a Noble Earl.
The present Lord Happincron met Lord Ropney at Spa, in
the decline of life, when both his bodily and his mental powers
were sinking under the weight of years. The Great Comman-
der, who had been the bulwark of his country, and the terror
of her enemies, lay stretched on his couch, while the memory
of his own exploits seemed the only thing that interested his
feelings, or afforded a subject for conversation. In this situa-

tion,

OF THE LATE JOHN CLERK, ESQ. OF ELDIN. 129

tion, he would often break out in praise of the Naval Tactics,
exclaiming with great earnestness, “ Jonn Cxerx of Eldin for
“ ever.”

Generosity and candour seemed to have been such consti-
tuent elements in the mind of this gallant Admiral, that they
were among the parts which longest resisted the influence of
decay.

Soon after the victory obtained by Lord Ropney, the Ame-
rican war was brought to a conclusion, and the world enjoyed
some years of repose. The French Revolution disturbed the
tranquillity of Europe; Britain was quickly involved in a war
more formidable than that in which the principles of Mr
CuErx’s system was first essayed; one where it was yet to be
more severely tried, and was yet to render more important
services to the country.

We have seen, that Lord Ropnry had been so convinced by
the first explanation he received of Mr Crerx’s system, that
he declared, that should he meet the French fleet. “ he would
“ try his way.”—On Lord Howes, the effect of the first per-
usal of the same work was quite different, though the result in
the end was entirely the same. A copy of the first edition of
the Naval Tactics was sent to his Lordship, who, after read-
ing it, expressed himself as highly pleased with the ingenuity
of the book, and as greatly struck with the circumstance of the
author being a landsman ; but he nevertheless desired General
Cierx to inform his ingenious kinsman, that he would adhere
to the old system if ever he had an opportunity of engaging
the French fleet. To this Mr Crerx replied, through the
same channel, that if his Lordship did so he would infallibly
be beaten. His Lordship, however, when it came to the trial,
did not adhere to the old system, but, concentrating his force,
directed it against one point, precisely on the principles of the

VOL, IX. P. I. R Naval

130 FRAGMENT OF AN INTENDED ACCOUNT

Naval Tactics. His change of opinion may have arisen from
the practical commentary by which Lord Ropyry had illustra-
ted the principles of that work; and perhaps, too, a second
perusal of the book itself had materially contributed to this
effect. That Lord Howe really consulted it a second time,
there is good reason to believe. When he commanded the
Channel fleet in 1793, Mr James Cierx, the youngest son of
the author of the Naval Tactics, a young man of great pro-
mise, who, had he lived, would have done honour to the pro-
fession on which his father had bestowed so valuable a gift,
served as a midshipman on board the Admiral’s ship the
Queen Charlotte. He possessed a copy of the second edition
of his father’s book, which was borrowed by Captain Curi-
stTiaNn, no doubt for the Admiral’s use. Thus much is certain,
that the action of the 1st of June 1794, was, in its manage-
ment, quite conformable to Mr Ctrrx’s system, and its suc-

cess entirely owing to the manceuvre of breaking the line.
Lord Howe was also the first who introduced into the sig-
nal book signals directed to the object of cutting off the rear,
—of bringing the whole force to bear on one point,—break-
ing the line, &c. Indeed, if his Lordship’s conduct had been
contrary to the principles of the Naval Tactics, the words of
his declaration, that he would still adhere to the old method,
is a decided testimony in favour of one of the points which I
think it most material to establish. About the utility of the
method, after Lord Ropney’s action, no doubt could be enter-
tained. As to its novelty, and its originality, if any difference
of opinion could arise, it is completely answered by Lord
Howe’s message delivered to General Crerk, as it is a proof
that an officer of his Lordship’s great skill and experience,
considered this manceuvre as new, as opposed to the ordinary
practice, and as a thing hitherto unknown. The novelty of
the

OP THE LATE JOHN CLERK, ESQ. OF ELDIN. 131

the system, therefore, can no more be doubted than its. uti-
lity.

An example of breaking the line, with success, if possible,
more brilliant than either of the preceding instances, was af-
forded by Lord St Vixcenr’s memorable action on the coast
of Spain, when, disregarding, as he said, in his own account of
it, the regular system, he attacked the Spanish line of twenty-
seven ships with fifteen only, and by carrying a press of sail,
intersected and cut off the windward division, of which four
were taken before the rest of the fleet could work up to their
relief.

Lord Sr Vincenr had early been made acquainted with Mr
Cxzrk’s book, of which a: copy had been sent him by Colonel
Dzrsrse of the Royal Engineers, a particular friend of the au-
thor. 1 do not find that his Lordship ever expressed any opi-
nion on the principles of this work.

Lord Duwcan’s victory on the coast of Holland was achie-
ved on the same principle, and carried into effect with singu-
lar gallantry. His Lordship, indeed, before going to sea, had
many conferences with Mr Cuerx, and professed that he was
determined to pursue the plan of operations which he had
pointed out. His Lordship’s attack, accordingly, was directed
against the centre of the enemy, in consequence of which the
rear division was cut off and taken, with the exception of a
single ship. When the first news of this victory, so near to
our own shores, and therefore so strongly felt, and so highly
appretiated by us all, was brought to Walmer Castle, where
Mr Prrr was then residing, he, with Lord Mervitie, Mr For-
pycr, and some others, were sitting at table just after dinner.
A man who had seen the action, and had just landed, desired
to be introduced, and on coming into the room, gave an ac-
count of what he had witnessed ; on his mentioning that Lord

R2 Duncan

132 FRAGMENT OF AN INTENDED ACCOUNT

Duncan had broke through the Dutch line, Lord Metvitie
immediately exclaimed, Here is a new instance of the success
of CLERK’s system.

The last and greatest in the brilliant series of victories that
followed the publication of the Naval Tactics, was, like all the
rest, obtained by the skilful application of the principles there
unfolded ; and of this, Lord Netson’s instructions, before the
battle, are the fullest evidence. They even contain, in the
body of them, several sentences that are entirely taken from
the Naval Tactics. These instructions were transmitted to Mr
Cuerk by one of the Commanders in that memorable action,
Captain, now Admiral Sir Purr Durnam, with a note, which
shews in what light his discoveries were viewed by those most
capable to decide. “ Captain Duruam, sensible of the many
“ advantages which have accrued to the British ‘nation from
“ the publication of Mr Crerx’s Naval Tactics, and particu-
“ Jarly from that part of them which recommends breaking
“ through the enemy’s line, begs to offer him the inclosed
“ form of battle, which was most punctually attended to in the
“ brilliant and glorious action of the 21st of October. Mr
“ Crerx will perceive with pleasure, that it is completely ac-
“ cording to his own notions, and it is now sent as a token of
“ respect from Captain Duruam, to one who has merited so
* highly of his country.

“ H. M.S. off Cadiz, 29th Oct. 1805.”

I must observe, that the Great Admiral, to whose last and
most glorious action I have now alluded, had put in practice
the same manoeuvre in the Battle of the Nile; the line was
then broken in the same way, and the discomfiture, by that
means, of a fleet at anchor, was the most complete that can be
imagined,

From

OF THE LATE JOHN CLERK, ESQ. OF ELDIN. 133

From the whole of this narrative, therefore, it is plain, that
the Naval Tactics was acknowledged by professional men, as
an original and valuable work, unfolding a new system; the
advantages of which were proved by demonstrations founded
on the most undeniable principles, and now verified by a se-
ries of great and brilliant victories, in consequence of which
there has been effected an entire revolution in the offensive
part of naval warfare. These truths having been so generally
acknowledged and admitted, both by Naval Officers of the
highest reputation, and by Statesmen of the greatest power, it
cannot but appear extraordinary, that no mark of public fa-
vour was ever bestowed on the author, nor any acknowledg-
ment made by Government of merit so distinguished. It was
merit of the kind most directly calculated to interest the feel-
ings, and to call forth the gratitude of the Nation ; it was an
improvement in the art which Britain reckons so peculiarly
her own ; it was a contrivance for making more effectual the
arms in which she most confides ; for rendering more impene-
trable the Wooden Walls, to which she trusts her safety, her
prosperity, and her independence. The name of Mr Crenrx,
and of the Naval Tactics, is in the mouth of every Officer,
from the Midshipman to the Admiral.

Whatever was the cause of this strange omission, it is deep-
ly to be regretted,—regretted, however, much less on account of
Mr Cuerk, than on account of the Nation itself. Toa man
conscious of having rendered so important a service to his
country as he had done,—who might say to himself without va-
nity, that he was entitled to be numbered with her most use-
ful citizens, and her most eminent benefactors,—who saw that
the actions which had immortalized the names of Ropwey,
Hower, Duncan and Netson, had been all directed by a prin-

ciple

134 FRAGMENT OF AN INTENDED ACCOUNT

ciple which he had been the first to discover,—and who
knew, that he was to go down to posterity as the author
of a great and important improvement ;—to the happiness
of a mind sustained by such reflections, and inspired by
the sentiments which must accompany them, what great
addition is it in the power of a Monarch, or even of the
Nation, to make? what is it that the common badges and
titles of honour and distinction can be supposed to add?
These may be fit, and even necessary emblems, for marking
degrees of merit of an ordinary kind ; but when merit is trans-
cendant to a certain point, it can dispense with such conven-
tional symbols; it shines of its own light, and enables its pos-
sessor to look down on the neglect or the ingratitude of the
world.

But though these considerations may in some measure set
us at ease with respect to the author himself, and his own
feelings, it must be allowed that they take nothing from the
blame incurred by those to whom the Nation had intrusted
the power of dispensing its honours and rewards. Neglect
of merit will always operate as a discouragement to exertion,
and every instance of it tends to extinguish a portion of the
fire of genius, of that which often constitutes the sole riches of
the possessor, and is always a valuable portion of the patrimo-
ny of the State. Every mind is not provided with the power
of enduring neglect ; ingenious men are often the most sen-
sible of it; and it is hard that the possession of talents should
be converted into a source of suffering. If the author of the
Naval Tactics had not been supported by such enlarged views,
and such high sentiments as we have mentioned, the circum-
stances of his case would have pressed on him with much se-
verity.

That

OF THE LATE JOHN CLERK, ESQ. OF ELDIN. 135

That it was not ignorance of the facts, or of the chain of
evidence now brought forward, that prevented a public ac-
knowledgment of Mr Crerx’s services, is altogether certain.
The late Lord Mexvitiz, who held so conspicuous a situation
in the government of this country during the greater part of
the period I have been treating of, was early made acquainted
by Mr Crerx himself with his ideas on the subject so often
mentioned ; and in the beginning of his political career, when
yet King’s Advocate in Scotland, was consulted on the best
means of bringing forward those ideas, and gave his advice
with the readiness and frankness for which he was remarkable
in all situations of life. It is apparent, that he never ceased
to hold Mr Crerx’s discovery in the highest estimation ; and
of this, his observation at Walmer Castle (on hearing of Lord
Douncan’s victory above related) is a sufficient proof,—an obser-
vation that conveyed a severe censure on himself, and on the
Minister to whom it was addressed, unless they both felt that
their power of rewarding the merit in question was restrained
by some considerations known to themselves, and invisible
to the public at large.

Lord Metvitte had particularly studied the affairs and the
interests of the Navy ; he had been for a long time at the head
of the Admiralty ; and there is reason to think, that he was
sensible of the improper neglect, with which the Author of the
Naval Tactics had been treated. I have been assured that he
had represented this to Mr Pirr, but when it was too late, and
when that Minister was drawing near the end of life.

If I might venture any conjecture on the cause of an omis-
sion which it is impossible to justify, I should be disposed to
ascribe it to the fear of giving offence to the Navy, and to con-
sider it rather as resulting from an excess of caution, than

from

136 FRAGMENT OF AN INTENDED ACCOUNT

from direct or intentional neglect. It might seem to derogate
from the glory of our Naval Officers, to recognise a Landsman
as the author of one of the most valuable discoveries that had
been made in their own art,—as the person who had not only
pointed out the new principle, but had completely unfolded its
advantages, and predicted its effects. If this were the ground
on which the reward was withheld, it must at once be consider-
ed as very insufficient for the purpose of justification. The man
entrusted with the power of rewarding merit, ought no more,
than those who have committed to them the office of punish-
ing guilt, to be accessible to any voice but that of truth and
justice. The little and mean jealousies that may be excited,
by an impartial discharge of their duty, ought never to in-
terfere with the performance of what is imperiously called for.
Jealousy, in the present instance, was a weakness that deserves
no indulgence; it was vanity and selfishness that ought to
have met with no sympathy, no toleration. If, indeed, such
feelings any where exist, there is fortunately no reason
to think them general; and it is a duty which I most
willingly discharge, to say, that the Naval Officers with
whom I have had the honour to converse on this subject,
have all in the most unequivocal terms expressed their
conviction of the importance and originality of Mr Crizrx’s
discovery. That there are exceptions to this rule, I can only
state as a conjecture, necessary to explain what is otherwise so
difficult to be accounted for.

But to whatever cause the neglect of which I now complain
is to be attributed, it is certain that the Government and the
Navy have both lost a great opportunity of doing honour to
themselves. A National Monument, that would have marked

the era of this great improvement, and testified the gratitude
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IX. On Circular Polarisation, as exhibited in the Optical
Structure of the Amethyst, with Remarks on the Distribution
of the Colouring Matter in that Mineral. By Davin
Brewster, LL. D. F. R. 8S. Lonp. & Enin, *

(Read November 15. 1819.)

In plates of Rock-Crystal cut perpendicular to the axis of
the prism, an unusual kind of polarisation had been observed
in the colours seen along the axis. The phenomena were
subsequently analysed by M. Bror, who remarked, that in
some specimens of quartz, the succession of tints appeared
by turning the doubly refracting prism from right to left, while
in other specimens the same succession was developed by
turning the prism from /eft to right; and he concluded from
his experiments, that the quartz impressed upon the particles
of light a rotatory motion, and that this property belonged to
the ultimate particles of silex, and was independent of their
mode of aggregation.

The same species of colours was afterwards. observed, about
the same time, by MM. Bror and Sgreseck, in transmitting
polarised light through considerable thicknesses of some essen-
tial oils, and solutions of sugar and camphor; and this new

s 2 fact

* The properties of Amethyst, described in this paper, were discovered in 1817;
and were announced to the Royal Society on the 18th January 1819.

140 ON CIRCULAR POLARISATION, AS EXHIBITED IN THE

fact seemed to confirm the supposition that the colours were
not dependent upon crystallisation.

My attention was particularly directed to these phenomena,
(which we shall distinguish by the name of Circular Polarisa-
tion,) in consequence of having discovered distinct traces of
them in crystals with two axes. The tints appeared at the
poles of the resultant axes, and the same crystal seemed to
unite the properties of both the varieties of rock-crystal.
Another specimen of the same mineral was entirely destitute
of these tints, so that I could not avoid drawing a conclusion
opposite to that of Bior, and of supposing, that, in this case at
least, crystallization had some share in the production of the
tints. This conclusion received no slight confirmation,
when I discovered the double system of rings in crystallised
sugar, and found that they exhibited none of the phenomena
of circular polarisation, although these phenomena are finely
developed in a solution of that substance.

If the property of producing circular polarisation, were es-
sential to the particles of silex, it is not easy to understand
why it is not exhibited, to a certain degree, by all the siliceous
substances, and particularly by Opal and T'abasheer, the for-
mer of which contains above 90 per cent. of that earth.

The great resemblance of Amethyst to Quartz, both in erystal-
lisation and chemical composition, induced me to examine it
with particular care. WERNER had boldly attempted to
draw a distinction between these minerals, which the less
practised eye of other mineralogists had confounded; and it
will be considered as no ordinary proof of his wonderful saga-
city, that this distinction has been fully confirmed by the op-
tical results which it is the object of the present paper to de-
scribe.

Having procured above 60 Amethysts, principally from the
Brazils, some of which were Jilac, others yellow, others green,

and

OPTICAL STRUCTURE OF THE AMETHYST. 141

and some perfectly colourless, I cut various plates of them per-
pendicular to the axis, and examined them when exposed to
polarised light. A structure of a very extraordinary kind pre-
sented itself; but in most cases it was so minute, that I was
obliged to analyse the emergent light by microscopes of Agate
and Tourmaline*. When the structure was regular, three sepa-
rate sets of veins were seen, as shewn in Plate X. Fig. 1. which
represents a plate cut from the pyramidal summit of a pink-
coloured amethyst.

The veins resembled a number of V’s inclosed in one another,
and each set was opposite an alternate face of the prism, the apex
being directed to the centre. Upon examining these alternate
veins, I found that the series distinguished by a faint blue
tint, produced the succession of colours, by turning the prism
from right to left; while the series with a faint yellow tint pro-
duced the same succession, by turning the prism from left to
right f.

Each of these fringes was placed between two of an oppo-
site character, and separated from them by a black fringe,
where the crystal produced none of the tints of circular polari-

sation,

* After I discovered that the Agate gave a single polarised image, in conse-
quence of the dispersion, and partial absorption, of the rays which form the other
image (See Phil. Trans. 1813, p. 102. and 1814, p- 189.), I employed it constant-
ly as a part of my apparatus, as may be seen in the Phil. Trans. 1814, p. 203,
206, 208, &c. &c., and when the aid of a microscope was necessary, I cemented
a thin plate, with Canada Balsam, upon the plain side of a Plano-conyex Lens.
By the method described in the Phil. Trans. 1819, p. 146, I have extinguished ,
one of the images of Culcareous Spar so completely, that the place where it should
have been could not be distinguished, even in the strongest lights ; and I have ac-
cordingly used it as an analysing prism, in preference to the agate and the tourma-
line. Epidote, Mica, and other substances which absorb one of the pencils, may
be employed for the same purposes,

+ See the description of the figures at the end of the paper.

142 ON CIRCULAR POLARISATION, AS EXHIBITED IN THE

sation, or rather where these tints were extinguished by the
opposite action of the two adjacent veins *.

In many specimens of Amethyst, these veins are distributed
with great irregularity, and sometimes they are so extremely
thin, that the two circularly polarising structures almost entire-
ly disappear, and leave the crystal with the power of producing
a system of rings with the black cross distinctly traversing
them. In those specimens where the circular tints are nearly
extinguished, the amethyst exhibits, in the most distinct man-
ner, two resultant axes, inclined to one another between three
and four degrees.

The black hyperbolic branches appeared, as is usual in cry-
stals with two axes, in an azimuth of 45, and different tints,
analogous to those of absorbing crystals, were seen within and
without these branches. The tints between the convex summits
of the hyperbolic branches, were sometimes of a deep purple,
and in other specimens of a pink hue; while the tints within
thesame concave summits, were of a slaty blue or of a reddish
white colour. The plane of the resultant axes was always per-
pendicular to the radius of the sector which exhibited the two
axes.

Phenomena similar to those which have been described,
are seen likewise in the olive-coloured amethysts, and in those
which are colourless like quartz ; and we are therefore entitled
to conclude, that the amethyst combines in itself both the

structures

nn nnn EEE EESSEEEESnSsSSSIEEESSENESSEEEnennnnenemenemeemeee

* If we consider Circular Polarisation as having its origin in a deviation from
the usual laws of crystallisation, the parts of Amethyst corresponding to the black
fringe may be regarded as produced under the influence of the usual laws, while,
during the formation of the opposite veins, between which it is interposed, the
crystallisation was subject to the unusual laws differently related to the axis, ac-
cording as the polarisation is direct or retrograde.

OPTICAL STRUCTURE OF THE AMETHYST. 143

structures of the two optical varieties of quartz ; that these two
structures are disposed in plates parallel to the axis of the
prism; that these plates are inflected into various forms, and
that they modify each others action, and are sometimes so mi-
nute as to destroy the circular tints which each of them would
have produced separately.

The “lac tints, from which the amethyst derives its peculiar
colour, and its value as a precious stone, generally (though
not always) reside in the veined part of the specimen; but
when the colour is removed by heat, neither the veins nor
their optical actions suffer any change.

In some specimens I have found the red colouring matter
arranged in veins corresponding with the dark spaces where
the two structures destroy one another.

This phenomenon is finely seen in the amethyst represent-
ed in Fig. 1. which has the appearance shewn in Fig. 2. when
narrowly examined with common light, and also with pola-
rised light, the colour of the veins varying in different posi-
tions, according to the quantity and nature of the tint, ab-
sorbed in different azimuths *. In order to explain the distri-
bution of the colouring matter in this and similar specimens,
let a, a, a, a, a, a, &e. Fig. 3. be the black lines which separate the
two structures, and let 6,6,6, b,0',b,, &c. be the lines where
the one structure has begun to affect the tint of the opposite
structure, then the’ colouring matter begins at the line 3, d, 8,
and gradually increases till it is a maximum at aaa, from
which it again diminishes, and becomes a maximum at J’, 8’ 0’,
and so on, increasing and diminishing in a similar manner.
These tints vary in different azimuths, being sometimes purple

in

* See Philosophical Transactions, 1819, p. 11.

144 ON CIRCULAR POLARISATION, AS EXHIBITED IN THE

in the plane of primitive polarisation, and pale-red in a plane
at right angles to it.

In another amethyst, shewn in Fig. 4. the portion A gave
the retrograde tints, and B the direct tints: the direct veins
were lilac ; the retrograde veins brownish-red; and the dark
lines yellowish- white.

In other crystals the colouring matter affects the largest
masses of the structure, such as those left white in Fig. 1. which
separate the veined sectors. In a very interesting speci-
men, shewn in Fig. 5. the lines AE, BF,.DG, which divide
the hexahedral crystal into triangular prisms, are distinctly
seen by common light; and one of these prisms, BCD, is
alone tinged with the red-colouring matter. Upon exposing
this crystal to a polarised ray, I found that the sector BCD,
consisted of two opposite structures a, 6, separated by the
curved vein mn, where their opposite actions were in equi-
librio ; and hence it follows, that the colouring matter affected
all the three structures of the specimen. This subdivision of
the crystal into hexahedral prisms, seems to indicate that the
dodecahedron may be formed by two intersecting rhomboids, .
to which the two structures may be related.

In a large white amethyst, tinged with masses of yellow,
I found that the yellow-colouring matter resided in three une-
qual sectors, A, B, C, Fig. 6. all the rest of the crystal, consist-
ing of narrow veins of the opposite structure, which became so
minute as to destroy one another almost entirely in the sector
D, which exhibited in the highest perfection the two axes and
the hyperbolic branches. The sectors A and C were, as it
were, expansions of direct veins, while B was the expansion
of a retrograde vein, and B and C were separated by a dark
line, from which the tints ascended to a green of the second
order,

Among

OPTICAL STRUCTURE OF THE AMETHYST. 145

Among the numerous amethysts which I prepared for exa-
mination, there was one of a very interesting nature. One
half of it was yellow, and the other dilac. The yellow half ex-
hibited the tints of circular polarisation ; but the /ilac half
seemed entirely destitute of them. The application of the
microscope, however, displayed in the lilac portion a sort of
rippled structure, like that of the agate *, and I distinctly saw
various remaining specks of the two structures, by whose oppo-
sing agencies the circular tints had been extinguished. This
specimen is shewn in Fig. 7. where B is the yellow, and A the
lilac portion, separated by a sharp line m n.

In another specimen, represented in Fig. 8. but without any
natural faces, the one half A had the direct circular polarising
structure, while the other half B had the retrograde structure,
and the junction of these opposite tints was marked by a black
line m n, from each side of which the colours ascended in the
scale to the Greenish Pink of the second order. The part of
the crystal corresponding with the black line was colourless,
while both the portions A and B had a dark-yellow tinge.
This black space constantly occurs between the two opposite
structures ; though I have various specimens, such as that in
Fig. 11. where the same structure appears to exist on both
sides of it. I have always found, however, upon minute exa-
mination, that in this case the second structure ewists in the
middle of the irregular black space, having nearly exhausted it-
self in neutralising, to a certain extent, the opposite structure
which encircles it.

Although the. veined structure, when it is regular, most
commonly resides in the alternate sectors of hexahedral pyra-
mids of amethyst, yet I have found specimens in which it is
placed in a different manner. In a colourless, and also in

VOL.IXe PI. T an

* See Phil. Trans. 1814, p. 192; and Pl. V. Fig. 1, 2.

146 ON CIRCULAR POLARISATION, AS EXHIBITED IN THE

an olive-coloured amethyst, the whole of the specimen is oc-
cupied with the veined structure, as shewn in Fig. 9. each sys-
tem of veins covering a sector of 120°. In another specimen,
shewn in Fig. 10. the veined sectors were four in number, two
of them corresponding, as at B and D, with opposite sides
of the hexagon, and the other two corresponding, as at A and
C, with two of its opposite angles. In this last specimen the
veined part was tinged with pink, and the crystal was foul near
its axis. In another specimen, Fig. 11. which contained part
of the pyramid, and part of the prism, of a very fine crystal,
the veined structure occupied all the half ABCDA, which was
nearly colourless; and the other half AFEDA, which had cir-
cular polarisation, was of a yellow colour, excepting in the two
places where the opposite tints had extinguished one another.
In the parts a and c the tints were retrograde, and in 6 di-
rect.

The finest specimen of amethyst which I have ever seen, is
shewn in Fig. 12. which is drawn of the natural size, and
which represents a section of part of the pyramid and part of
the prism. On the three alternate sides of the prism, viz.
MN, OP and QR, are placed sectors MeN, OdP, QaR,
which are divided into two parts by dark lines ce’, dd’, ad,
which separate the direct structures of A, C, and E from the
retrograde structures of B, D,and F. On the other three al-
ternate faces of the prism are iplaced the'three veined sectors
McbaR, NebdO, and Pdba Q, which meet at 6 in
angles of 120°, and consist of veins of opposite structures al-
ternating with each other, and so minute, that in many places
the circular ‘tints are almost wholly extinguished by their ‘mu-
tual‘action. The direct sectors A, C and E are all connected
together by the three radial veins Ga, bc, 6d, ‘and ‘are there-
fore to be considered as the expanded terminations of ‘these

veins.

OPTICAL STRUCTURE OF THE AMETHYST. 147

veins. The retrograde sectors B, D and F are expansions of
the first retrograde veins next to dic, dba and abc; and
the lines cc, dd’ and aa are continuations of the dark or neu-
tral lines which separate the first pee He vein from the di-
rect radial veins.

All the sectors A, B, C, D, E and F, are of a yellowish-
brown colour, and all the rest of the crystal is of a pale lilac
colour ; the lilac tints being arranged in the manner previous-
ly described. ‘The phenomena which I have now mentioned
as existing in this specimen are very common in the ame-
thyst ; and I have never yet: found a specimen in which the
yellow tints were not confined to those portions which formed
the expanded termination of veins, a fact which indicates that
this would have been the colour of the crystal, whether its ac-
tion were direct or retrograde, and that the lilac colour af-
fects in general those portions which are composed of oppo-
site veins.

Hitherto we have considered the appearances exhibited by
amethyst in a direction coincident with the axis of the prism.
When we examine it in a direction transverse to the axis,
we receive no assistance from the phenomena of circular pola-
risation, as the force by which they are produced extends on-
ly to a very small distance from the axis; but the structure of
the crystal is fortunately rendered obvious by other means.
In Fig. 13. we have represented a section of the pyramid of ame-
thyst, cut by a plane parallel to one of the faces of the pyramid,
in order to explain the several phenomena which it displays. The
upper pyramidal layer ABC is commonly pink, but often brown-
ish or bluish, and composed of strata of different shades of colour.
The next layer is yellowish white ; the third layer DE is pink
like the first ; the fourth layer is yellowish-white ; and the fifth
layer FG is like the first and third, being succeeded by a

ries yellowish-

148 ON CIRCULAR POLARISATION, AS EXHIBITED IN THE

yellowish-white one. All these strata are sections of the
planes of the primitive rhomb, the third plane being per-
pendicular to the eye. These layers are crossed by the veins
ab, cd, turning away from the axis at their summits, so
as to fall more perpendicularly upon the faces AB, AC as
they approach to B and C. Lach alternate vein is pink
where it traverses the pink layers, and of a deeper yellow
where it traverses the yellowish-white layers. I was now
anxious to ascertain whether there was any difference in the
mechanical state of those parts of the veins which gave the
black fringes, and those which produced circular polarisation,
as the veins were often visible in common light, an effect
which could arise only from a difference of mechanical or of
refractive density. With this view, I cut a plate about >,th
of an inch thick, out of a large amethyst, by planes passing
through the axis. Having divided this plate into two parts,
I placed the one above the other, so as to counteract its pola-
rising and doubly refracting forces, and exposing it to polari-
sed light, I had a system of rectilineal tints M, N, Fig. 14. of
opposite characters, separated by the black fringe AB, all of
which were perfectly free from the tints of circular polarisation *.
Upon examining them withan analysing microscope, I distinct-
ly observed, that they were crossed with the veins of the ame-
thyst, though these veins were entirely invisible either in ordi-
nary or polarised light previous to the super-position of the
plates. The tints produced by the ordinary polarising force were
always a minimum at the lines corresponding with the black frin-

ges

* Plates of Rock-Crystal cut and arranged in this manner, form the best com-
bination for exhibiting the different orders of colours.

OPTICAL STRUCTURE OF THE AMETHYST. 149

ges which separated the direct and retrograde structures, and
increased to the centres of these structures, from which they
again diminished to the adjacent limit of the next. vein.
Hence we deduce the important. fact, that the direct and
retrograde veins in Amethyst have a greater polarising force,
and consequently a greater force of double refraction than
the interval between them, corresponding with the black fringe.
As the two structures pass into one another, through this line
as their node, by insensible gradations, we cannot avoid con-
cluding, that the cause, whatever it may be, which gives to
the particles of Quartz the peculiar arrangement that produ-
ces circular polarisation, gives them, at the same time, when
thus arranged, an increase of polarising and doubly refracting
force.

These results, considered merely as optical facts, would
have entitled mineralogists to separate Quartz and Amethyst ;
and it is highly probable, that the two varieties of quartz, and
the amethyst, will be found to exhibit some remarkable differ-
ence in their crystalline structure, to which the difference in
their optical properties may be ascribed. It is fortunate, how-
ever, that the optical structure which we have pointed out dis-
plays itself by precise mineralogical characters. The combi-
nation of veins may be seen even in common light. They ap-
pear cropping out, as it were, upon the alternate faces of the
pyramid, as shewn in Fig. 1. at A, C, and E; or on all the
faces when. the whole prism is pervaded by the veined struc-
ture, and the fracture across. the veined portions, exhibits a
beautiful, and sometimes a regular rippled structure, not un-
like the engine-turning on the back of ornamental watches.
This rippled structure, which I have attempted to represent in
Fig. 15. is an infallible proof that. the specimen is amethyst,
whether it is yellow, orange, olive-green, lilac, or perfectly co-

lourless.

150 ON CIRCULAR POLARISATION, AS EXHIBITED IN THE

lourless. The fracture in the direction of the black fringe is
rough, and along the two opposite veins polished ; so that in
specimens that have been injured, we can see even ina direc-
tion transverse to the axis, as in Fig. 13. the veined struc-
ture distinctly marked by a succession of opaque and transpa-
rent lines.

During the preceding experiments, I remarked the follow-
ing property of cireular polarisation, which enables us to as-
certain whether the structure is direct or retrograde, without
employing an analysing prism.

Let AB, Fig. 16. be a plate of amethyst, one half of which
APQ has the direct circular polarising structure, and the other
half BPQ the retrograde structure. Let the plane of primitive
polarisation MN coincide with PQ. If we now take a plate of
sulphate of lime, which polarises a white of the first order, and
place its axis parallel to MN, it will not affect the tints in ei-
ther half of the plate AB, which we shall suppose to be a
white of the first order. If the axis of the sulphate of lime is
shifted to CD, it will raise the white tint of the direct portion
to a yellow, growing brighter as it moves round, and becoming
orange, red, pink, and blue ; the blue becoming fainter, and ter-
minating in white, when CD reaches the position BA. If the
axis of the sulphate of lime moves from MN to cd, the white
tint of the direct portion will become faint d/we, then more
blue, then pink, orange, and yellow. The effect on the retro-
grade structure is quite the reverse of this, the one becoming
blue when the other is yellow; but the resulting tint is always
the same, whether a plate of sulphate of lime crosses the direct
or the retrograde circular tint.

The properties of amethyst which have now been described,
render a plate of this substance'a valuable addition to our ap-
paratus

OPTICAL STRUCTURE OF ‘THE AMETHYST. 151i

paratus for conducting experiments on the polarisation of
light. If we wish to place the principal section of the analy-
sing prism exactly in the plane of primitive polarisation, we
have only to interpose a thin plate of amethyst, like that
sshewn in Fig. 1., and if the tints of both sets of veins are ex-
actly similar, the analysing prism will have the required posi-
tion. Ifthe one set of tints is bluer or whiter than the other,
or if there is the slightest difference between them, the posi-
tion of the prism must be altered, till that difference is no
longer perceptible.

If we wish to place a plate of sulphate of lime, or any other
crystal, so as to have its principal section in the plane of pri-
mitive polarisation, the interposition of the amethyst plate will
give us the same assistance, by indicating that the circular
tints are not affected by it; whereas if we wish to place the
axis of the sulphate of lime at an angle of 45 to the primitive
plane, the amethyst will point out this position, when the op-
posite circular tints suffer an equal change.

The observations contained in the preceding pages are the
results of an immense variety of experiments, which acciden-
tal circumstances put it in my power to make upon this inte-
resting mineral. Having had access to whole bagfuls.of ame-
thystine pyramids from the Brazils, in the possession of Mr
ALEXANDER, lapidary ‘in Edinburgh, 1 ‘have examined some
hundred specimens; and though I have not been able to re-
present one-tenth part of the varieties of arrangement. assu-
med by the colouring matter and the veins, yet I have given
the most general, and, I trust, the most interesting of them.
I ‘have purposely omitted the different, appearances which
are produced by crossing the veins of different specimens, be-
cause they are deducible from established principles, and like-
wise other phenomena.of colour, which arise from the action
of a number of minute strata upon. light, when ‘it is made to
pass between them..

(. 162) 0+

DESCRIPTION OF THE FIGURES IN PLATE X.

In all the Figures of this Plate, which have been coloured in order to repre-
sent the two structures, the direct and retrograde veins are distinguished by a
slight difference of tint,—a difference which is actually produced by turning the
principal section of the analysing prism a slight degree out of the plane of primi-
tive polarisation. When the principal section of the analysing prism is exactly in
the plane of polarisation, the tints of the two structures are perfectly alike, when
the veins are of the same size.

Fig. 1. Is a plate cut out of a pyramid of Amethyst, and about ;'5th of an inch
thick. The blue and yellow yeins are separated by a black fringe, towards
the middle of which the tints gradually shade off, and no direct vein ever
passes into a retrograde one, without the interposition of a black fringe. The
veined structure appears on the alternate faces of the pyramid, as shewn in
the Figure.

Fig 2. Shews the arrangement of the colouring matter in the veined sectors.

Fig. 4. Shews a form of the veins which is not very common.

Fig. 5. In the sector GCF of this Figure, I have shewn an arrangement which
the double structure sometimes assumes; though it did not occur in the spe-
cimen represented in the Figure, and already described.

Fig. 6. Shews the structure of an Amethyst perfectly colourless, excepting in
the three coloured sectors, which were yellowish by common light. The
thickness is about 0.32 of an inch.

Fig. 7. In this specimen the half m AC m shews imperfectly the veined struc-
ture in the part A, while in the part C small specks of the two structures
may be seen with a microscope.

Fig. 8. Is a specimen which has no veins, but merely the two structures, as
previously described.

Fig. 9. Is a specimen 0.47 of an inch thick, consisting wholly of direct and
retrograde veins. This Amethyst developes tints entirely different from any
that I have described.

Fig. 10. Is a remarkable specimen, and the only one of the same kind that
I have met with.

Fig. 11. In this specimen the retrograde portions a and ¢ were, as usual, sepa-
rated from the direct portion d by the black fringe m. The two portions a, c
were also separated by a black fringe; but I found that the remains of a di-
rect structure existed among the black masses between a and c.

Fig. 12. I consider this specimen, and the one shewn in Fig. 1. as exhibiting
the most general structure of well crystallised Amethysts.

Fig. 13. Represents the pyramidal strata of a pink colour, seen by common light
in a direction transyerse to the axis.

Fig. 15. Shews the fracture of Amethyst.

Xs

NN

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PLATE X.

Engraved tor the Reyat Sociew Prank Vot.IX Lage 152.

iv

ar)

Wi dicars Soulp? Bilin”

td

X. An Examination of some Questions connected with Games of
Chance. By Cuaries Bappace, Esq. F. R.S. Lonn. &
Epi.

(Read March 21. 1820. )

Tue questions which I propose to examine in the following
paper, although not themselves dependent on chance, have
arisen entirely from games in which it predominates. To de-
termine some method of betting upon a number of successive
events, (and the probability of each of which is either equal
to, or less than one-half,) by which a profit shall be realised
after a considerable number of them have been decided, is a
problem which has occupied the attention, and exhausted the
efforts, of one set of speculators, as completely as that of the
quadrature of the circle has defeated the labours of another.
The first and most simple plan, is that of doubling the stake
whenever a loss occurs. This is well known, and has been so
frequently practised, as to have acquired a peculiar name; it
is technically called the martingal ; it requires for its success,
that the person who employs it have the power of leaving off
whenever he please, and that he have the command of an un-
limited capital. If the chance of the events happening is one-
third instead of one-half, the stake must be tripled. Suppo-

VOL. IX. P, I. U sing

154 AN EXAMINATION ‘OF SOME QUESTIONS

sing a player adopt this system in betting on a number of in-
dependent events, the chance of occurring of each of which is
one-half, he would naturally desire to know, if possible, be-
fore he began, what would be his profit or loss, supposing p
of the events decided in his favour, and q against him. In
this particular plan of playing, it so happens, that he cannot,
from the mere knowledge of the number of favourable and of
unfavourable events, arrive at the conclusion he desires, I
shall presently show, that these data alone are insufficient, and
that, in order to determine the question, not merely the num-
ber, but the order of succession must be given. -

It is probable that this difficulty, in the case of most fre-
quent occurrence, has deterred many from attempting other
similar problems. Indeed, on the first view of such questions,
it is by no means apparent, that any of them can be solved
without reference to the order in which the events take place.
The mode of inquiry which I shall point out, will show that in
many cases their mutual arrangement is not required amongst
the data, and will furnish a criterion by which we may deter-
mine, in any given case, whether it is necessary.

I shall first examine the case of the martingal, which, al-.
though the results it leads to are of a negative nature, will
introduce, us to the method of treating these questions, and
from its frequent practice is rather interesting,

Let us suppose a gamester bet a certain sum, 2, upon an
event whose chance of happening is one-half; whenever he
wins he repeats the same bet; but whenever he loses, he
doubles his last. stake. If he should win p.and lose, q
times, it is required to ascertain how much he will have won
or lost.

The first stake being 2u, which may. either be gained or
lost, we may represent the gamester’s profit after one event is

decided

=e

ner

CONNECTED WITH GAMES OF CHANCE. T53:

decided by 2u(—1)*, a being any whole number; for since
the nature of the number a is left undecided; whether it is an
even or an odd one, the expression just given will represent
either a profit or a loss. First, if a@ is an even number, his
next stake remains the same as it was before, or equal to 2u,
if it is an odd number; his second stake must be 4u. We must
therefore endeavour to find some function of @ which shall be
equal to 2u, when a is an even number, and become 4u,
when a is an odd one. A great variety of functions may be

ey aoe
found satisfying this condition; such are 2u x2 eae

Qu =, &c. and many others. Our choice amongst

the infinite variety which present themselves, must be direc-
ted by the ulterior operations of the gamester ; and, first, I re-
mark, that every stake must be equal to the constant quantity
u, multiplied by some power of 2. The next remark which
may guide us in this choice of a proper function is, that the
index of that power of 2 is determined by the number of times
(in, immediate succession) the event has been unfavourable,
reckoning back from the event about which the stake is pro-
posed: if, therefore, at any period, all the preceding determi-
nations have been unfavourable, the amount of the next stake
will be influenced by them all. It may also be noticed, that
the successive powers of 2 can be formed by the addition of

all the preceding ones, together with unity, thus,

1, 2°, 2°, 2°, 2°, 2+ 2°
14+2°=2,142°+2'=4, 14+ 2°49'+ 2°—8 and so on:
From these considerations it appears, that the function we re-
quire may consist of a series of functions, each multiplying the

U 2 successive

156 AN EXAMINATION OF SOME QUESTIONS

successive powers of 2. In order to determine these, let us sup-
pose that at some point of the game, the last event has proved
favourable ; then, by the conditions, the next stake is 2u; and
whatever be the course of succeeding events, 2u will always form
part of the stake ; therefore it need not be multiplied by any
function of a, b, c, &c. the letters which determine the winning
or losing of the subsequent events. We may therefore assume
2u as the constant part of every stake, without reference to
any particular order in their occurrence. If the failure or hap-
pening of this event is represented by (—1)*, @ being an odd
number in the first, and an even number in the second case,
we must multiply the next power of 2, or 2*, by some function
of a which shall vanish when a is an even number, and be-
come unity when it is an odd one. Sucha function is easily

found, and one of the simplest is edocs as . Thenext stake

is therefore u (2+ a 2) , whatever be the form of a.

The failing or happening of this event may be represented
by (— 1)’ , and the profit of the player by this event is then
represented by wu (2+- —— ‘ vice iy.

The third stake must comprehend the second power of 2,
and will be of the form

u(2+2 F(ab) +2° f, (a4):

If 6 is an even number, or the second event is favourable, in

that case, the new stake would be 2u; and therefore both
f (a, 6) and f, (a,b) must vanish. This will take place if each

—_— _—_ 6 .
has a factor of the form a and the new stake in con-
sequence

CONNECTED WITH GAMES OF CHANCE. 157

sequence becomes

1 2 2 Se pele Syi\e
uw { 242 =" f(a) + F2— SF (a, 8)}
fand f, not being the same functions as before. If a had been
an even number, we may consider the first bet as not having
been made, since it has no influence on the succeeding ones ;
and in this case the expression ought to reduce itself to

uw {2+o4—v"}

f(a,6) must therefore equal unity, and f, (a, 5) must vanish
when a is an even number. This gives

u {24+2° ——— +2 Pes (a, 4) } i

This expression is reduced to 2wu if 6 is an even number,
and to

4u + 4u f, (a, d)
when 0 is an odd one; f, (a, 6) must therefore be such a func-
tion of a, that when a is odd, it shall become unity, and when

—(— ae : °
even, equal zero ; Se is such a function, and we then

have for the third stake
u {e+e a —— ‘ alee \

The law by which we may represent the stake to be ventured,
after the determination of any number of events, is now
apparent ; had it not been sufficiently so, the same reasoning
which has been already explained at some length would have
assigned it for the fourth stake,

uw | eee EY pg EW) iE ged: Jey’. ——

We

158 AN EXAMINATION OF SOME QUESTIONS

We can now represent the profit or loss on each event, with-
out determining which’ of the two it is:

On the Ist he gaims u { a i (—1)°

2d uw foyr—ey' } (erty,
b “a PSE Se FEET |
3d u {e4+1—@1) 5 ee yt een ee es \ (—1)°
fe eas py ey ge ay CAME pag yolk
4th uw Pts canndwas
Uae Ly jet Cf) \ (—1)4

= §24 ay + 1G) * ey + BE’ REL)
at x: “

en
+H Le ep - Fen } en
&e. &e. &e.

The sum of all these is the object sought: with respect to that
part which multiplies 2 w, it is easily found ; it is

au { (—1)" +(-1) +(-1) +...&e.} ;

but we know that he has gained p, and lost g times; conse-

quently p of the quantities a, 6, c, &e. are even numbers, and

q of them odd ones; therefore the sum‘of the series, multi-

plying 2u, is p—gq, and the value of the part alluded to is
2(p—q)%-

So far, then, we can proceed by means of the data furnished in

the question ; but they are insufficient for its complete solu-

tion, on attempting to find the sum of that part of the expres-
sion

CONNECTED WITH GAMES. OF CHANCE. 159

sion in which (—1) has only one index, it appears: to be

wf y(n) +2 (— 1)" +3 (—1)' + ke) ;

and the knowledge that p of the letters a, 6, c, &c. represent
even, and’gof them odd: numbers, will not. assist us in deter-
mining the sum of this series; we must also be acquainted
with the order of succession of the even and odd numbers.
Another reason will afterwards be assigned, why it is not suffi-
cient merely to be acquainted with the number of favourable
and of unfavourable events, which may with more propriety
be stated, when some .other questions of a similar nature have
been examined.

Let us now consider another case, in which the amount. of
the sum staked on each event follows a different law, we will
suppose the following problem :

A gamester begins a series of bets on an event whose chance
of occurring is one-half, by staking the sum u. Whenever he
wins he makes the next succeeding stake less than, his last by
the quantity v; but if he lose, he then increases his stake by
the same quantity. Supposing he should win p times, and
lose q times, what will he have gained or lost!on the whole
number p+ q. '

His first stake being wu, his first profit may be expressed by,
u(—1)*, which will be won or lost according as u is even or

odd; inthe first case his next stake would be w—v, and in the

second it would be wu +v. « These two cases may be combined

into one, and thus expressed u—v(—1)*, and his second

ma —( ' ay i
profit will be {ee (—1)° by; his next stake will
beuu(—1)'+vif\d is, evens but it will be x—a(—1)-4»
if

160 AN EXAMINATION OF SOME QUESTIONS

if that number is odd. These may be represented thus:
u—v { (4g (= )}, and his third profit will be ©
b
[u—» {(-1y+-1)} ] Hy

the succeeding stakes are easily represented in the same man-
ner, and his profits stand thus :
u(—1)s
u(— 1), a6 { (—1)} (—1)
u(—1) —v { (—1)'+(—1) } (1):
u(—1)'—» { (—1)°+(—1) +(— 1) } (1)
a(—1f 0} Hl) Ft aid,

&e. &e.
the value of the part multiplying w, or

(— 1) + (—1)' + (—1)' + &e.

is easily found, since we know that p of the quantities a, 6, c,
are even numbers, and g of them odd numbers. The first

part of the expression is therefore
(p —q) u.
In order to determine the second part, we must observe,
that the expression ,
(a) K+ (a $0) C+ (A +b+e)d+ (Wt tc +d) et, &e.
is equal to the sum of all the combinations, two by two of the

quantities a’, b, c, &c.; and, moreover, that if these latter are
the

CONNECTED WITH GAMES OF CHANCE, 161

the roots of an equation, then the expression just written is
equal to the co-efficient of its third term. If we change a’
into (—1)’, 8 into (—1)*, ¢ into (—1)’, &c. it becomes the
same as the one whose value we are seeking. Hence then it
appears, that the sum of ‘all the quantities, multiplying v, is
equal to the co-eflicient of the third term of an equation whose
‘roots are (— 1)", (—1)’, (— 1)’, &c. or of the equation

o = a«—(—1)*.2— (—1).«—(—1).

but we know that p of the quantities a, b,c, &c. are even
numbers, and q of them odd ones ; therefore this equation has
p equal roots of the form +1, and q equal ones of the form
— 1, or the equation is

o= («—1)? (w@+ 1);
and the quantity which multiplies v, is equal to the co-efficient
of the third term of this expression, which is

at a ye igh a aS al ere i
erg hl Cel a 2

so that the profit of the gamester is
=(p—q)u—v (eo tet D. (1)

This result is entirely independent of the order in which the
events occurred ; and we may learn from the method that has
been employed for its solution, that whenever the sum of all
the winnings or monies 4 is a symmetrical function of the quan-
tities (— 1)*, (— 1)’, (—1)*, &c. the final conclusion will
not depend on the order in which the events succeed each

other, but on the actual number of favourable and unfavour-
able events.

VOL. IX. P. I. x Tn

162 AN EXAMINATION OF SOME QUESTIONS

In the instance we are now considering, if the number of
successful and of unsuccessful cases are equal, the gamester
who adopts this system of play will always win, for in that
case p= gq, and W,=pv; as a numerical example of the
formula just investigated. Let us suppose

A person stakes 100 shillings on the event of a piece of mo-
ney thrown into the air falling with one of its faces uppermost,
in preference to the other; whenever he wins he diminishes
his stake five shillings, and whenever he loses he increases it
by the same sum. Supposing he makes 800 successive bets,
and wins p, and loses g of them.

If p and q are equal, each being 400, his profit will be
400 x 5 = 2000 shillings.

From this it appears, that he will win even though a smaller
number than one-half of the events prove favourable. In or-
der to determine how many times he must win, that he may
neither lose nor gain on the whole number, we must make the
value of W equal to zero, putting p +g =a; this gives for
the required value of p

1 7 1 /w
patgletstgveta;

in the present instance, a= 800, «=100, v=5, which
gives

p= 4 (800+ 10) + 5 /100 + 800 = 405 + 15;

the lower sign being employed, we have p = 390.

In fact, on substituting this number in the formula (1) we
find that he neither wins nor loses money, although the num-
ber of unfavourable events has been greater by twenty than the

number of favourable ones. The other root of the equation
points

CONNECTED WITH GAMES OF CHANCE. 163

points out another limit, beyond which if the number of fa-
vourable events increase, he will lose money.

In the problem just examined, each stake depends on that
which immediately precedes it. Others may be proposed, in
which it is made to depend on the result of two or more of
the events which immediately precede, such is the following
one:

A gamester begins by staking a given sum u, and regulates
his succeeding bets in this manner ; if one of the two immedi-
ately antecedent to that which he is at any time making, have
been gained, and the other lost, the new stake is the same as
that last made ; but if both those bets have been gained, he di-
minishes his stake by the sum v; and if both have been lost,
he increases it by the same sum v. The first stake being u,
the first gain may be represented by u(—1)*; and as there
has only been one bet yet made, the second cannot be affected
by the law prescribed ; it will therefore be the same as the first,
and the profit arising from it will be w(—1)’. The third stake
depending on the two former, we must add to the quantity u
some function of a and 6 multiplied by v, which shall va-
nish if @ and 6 are one odd and the other even, and which
shall become —1 when they are both even, and +1 when

they are both odd. Such is the function — SS

the profit from the third stake may therefore be represented
by .
(,, 9 (—De4+ (— :
fee) beng

x2 and

164 AN EXAMINATION OF SOME QUESTIONS

and in a similar manner, we may find that which arises from
the fourth is expressed by

{uo (Oo + Se Suh, \ (— 1).

The mode of continuation is sufficiently obvious, and by ar-
ranging all these profits together, we have

pee
ae

{u—v (PEED) 1 (oy

fea) (sete cee ae

{ae (SEE EM SMM EDEN | ay
Gute (Sy? 4 Ue ey 4 Cnc

n ey ee
&e. &e.
The part which depends on w is easily determined to be
(p —q) u, where p and q are the number of successful and of
unsuccessful cases, the remaining part consists of —5 multi-

plied by a function of the quantities a, 4, c, &e. In order to
abridge as much as possible, I shall write a instead of (— 1)*,
b instead of (—1)’, and so on; so that ab will represent

(—1)"x

CONNECTED WITH GAMES OF CHANCE. 165

(—1) x (—1)’, or (—1)*t+* ; observing this, the fac-

tor multiplying — 5 will be expressed thus :

ae-+ be
ad+2bd+cd
ae+2be+2ce+de
af +2bf +2cf+2df tef
ag+2bg+ 2cg+2dg+ 2eg + fg,
&e. &e.
If to these were added the two series ab +bc+cd-+ &c.
and a(6+e+d-+e-+ &c.) the sum would be equal to twice
the sum of all the products, taken two by two of the quantities

a, b, c, &c. (and since these quantities represent (—1)*,
(— 1)’, &c. we have found in the last problem that it is

equal to (@—#— +). The part depending on v is
therefore
=a ee) ee) 1) tt be.
— (—1)* ((-1)' + (-1)'+ (-1)'+ &e.) }
The second of these series is evidently equal to
Gy @s—- Oy) =G1y Go):
the other series
(1) #8 (1) (1 (alti ke

cannot be determined merely by knowing how many of the

numbers a, 0, c, &c. are odd, and how many are even.
Still,

166 AN EXAMINATION OF SOME QUESTIONS

Still, however, the knowledge of the order in which the
events take place is not absolutely required. It will be sufficient
to know how many changes from odd to even, and vice versa,
occur between the quantities a, 6, c, d, e, &c.; for if there is
no change in going from a to 4, the first term will be + 1; but
if there is a change it will be — 1; and generally — 1 will oc-
cur as often as there is a change from odd to even, or from
even to odd in the series

a,.0,.C,.d, @, &C.

If, therefore, k denote the number of transitions, since
the number of terms is p+q—1, the value of the series
will be

ptq—2k—1;
and the whole value of the part dependent on v will be

— 3 { (p—al — (et) — (eta) + 24+ 1—(—1) (p—q) +1}

and the profit on the whole number of bets is
W = (p—a)u— § { (pa) — 2 (et 9) + 2k + 2—

(1) (p—a) $ (2)
if p=q, then
W, =+0(2p—k—1) (3)
k in the first of these expressions may vary from 0 to p-+g—1,
and in the second from 1 to 2p —1.

In order to compare this with an example, let the following
series

CONNECTED WITH GAMES OF CHANCE. 167

series of bets be made plus or minus, denoting their success or
failure : }

The profit is 440. Here p=6, g=1, fi Qo = 10;
4 = 100; and these values being substituted in (2) give
W = 440.

The next case I shall examine is one in which the amount
of each stake depends on the result of the three preceding
events.

Let the law by which the stakes are regulated be such, that
when the three preceding have been won, a certain sum v is
taken from the last stake; if they have been lost, the sum v is
added to the last; but if only two of these three have been
gained, or only two lost, in the first case one-third of v is sub-
tracted, and in the second case is added to the last stake.

The first stake being u, the three first bets will be repre-
sented by u(—1)%, u(— 1)’, u(—1)._ In order to fulfil the
conditions of the question, the fourth must be increased by

the quantity —v et a (—)*; and the profit re-
sulting from it is represented by
{ Meld leew Lee ue: (S25 \ (—1)4

that of the fifth is equally expressed by
194 (eye, CD'+ ented) » C2)

The

168 AN EXAMINATION OF SOME QUESTIONS

The succeeding terms need not be written down, as the law is
obvious. In this, as in the former questions, the co-efficient
of u is p—gq; and if we employ the same abridgment of a

for (— 1), &c. as in the last, the co-efficient of — 5 is
ad+ bd+cd
ae+ be +2ce+de
af + 2bf+ 8cf + 2df + ef
ag + 2bg4+ 3cg + 3dg + 2eg+ fg
Sie: Sccc:

This series, which only differs from three times the sum of
all the products, two by two of the quantities a, 6, c, &c. by
the omission of certain parts, may be called Q. On examining
what parts are omitted, it will be found that

Q+2a(S(a+s+..)—a—b—c) +d

i b(S(a+b+..)—a—b—c)
+ (cetdftegt+..)+2(cd+de+tef+..)
+ 3(ab+act+bc) = 38(ab+..)
— 3 @=9=0t0.

This equation becomes, by the mutual destruction of certain

terms
Q+ 2aS(a+b+4+..)+5b3(a+6+..)+(ace+bd+cc+..)
ote beds!) Sse eee

Hence

CONNECTED WITH GAMES OF CHANCE. 169

Hence
Q=3 PHP Ot —2(—1)' (p—g) — (—1)' (p—) + 8 —
—(act+bd+ced+..)—2(bc+ced+...). —
The latter of these series is
at eas acl) al ccs el Gand aa
= p+q—2k—1—(—1)**,
as we found in the last question, k being the number of
changes from even to odd, or vice versa, in the series a, b, c,..
The value of the series
(— 1) + (— dye + (= 1)cte -f-',.;
is not determined without some other data. If, however, we
are acquainted with the number of alterations from odd to
even, and the contrary, in the series
G60 DOC ed fi".
we can assign its value; let the number be J, then the series
in question is equal to p+ q—2/1—2: These substitutions
and the necessary reductions being made, we have

Q=(p—g) {8*34 —2(-1"— (1) (p+) J

+74 2144h42(—1ete
and W the profit on p+ q events is

Was: Oiles a tate a 80)
=a L7—(@+q $421 +4k42 (194) (4)
if p=q
W,=—§ [7-9 p+2144h42(—1)+} (5)

VOL. IX. P. I. Y In

170 AN EXAMINATION OF SOME QUESTIONS

In the first of these expressions, k may vary from 0 to
p+q—1, and / from 0 to p+ q—2; in the second k may
vary from 1 to 2p—1, and / may vary from 0 to 2p —2.

The last question which I shall examine is one in which
each stake depends on all those which precede it.

A gamester stakes a certain sum w on an event whose
chance of happening is one-half. He regulates each succeeding
stake in this manner: To the constant sum w he adds the
nth part of all his previous winnings; or if he has lost by
the previous stakes, he subtracts the nth part of his loss, it
is proposed to find his profit * at the termination of p+ q
bets.

The first stake being w, the profit is wu (— 1)*; the nth part

of this added to u, or u+ “ (— 1)? will constitute the second,
and the profit will be w(—1)’+ “ (—1)* (— 1)’, the nth

part of these two, or ((— 1)¢+(— 1)) + “, (— 1)" (— 1)’

added to the quantity u, will be the third stake, and the profit

on the determination of the third event will be
u(t £ (t+ (HD) Cl + 8 (1
the

* The language of analysis is so much more general than that in which we
usually convey our thoughts, that it is almost impossible to make the latter keep
pace with the former. This is more particularly manifest when we are treating of
games of chance. The words profit, winning, gain, &c. must, if we wish to avoid
perpetual repetition, frequently be understood to comprehend their very oppo-

sites,

we

CONNECTED WITH GAMES OF CHANCE. 171

the nth part of the sum of these three profits added to uw, and
multiplied by (—1)¢, gives for the profit on the fourth event

u(— 14+ 2 (1) (+ HY (H+ HY (—b’)
+4 (Ci Cl C+ Cl Cy CI) + (1) (— 9 ())
+ % (1 (1 1)" (4.

From these expressions, continued a few steps further if ne-
cessary, it appears that the sum of all the profits W is equal
to

u multiplied by the sum of all the quantities

Cae as. \(— 1)",

multiplied by the sum of all the products, two by two

sis

+

of those quantities.

| Ss

+ 3 multiplied by the sum of all ne products, three by

three of the same > quantities.

Is

ame FONE by the sum of all the products, four by four

of the same quantities.
&e.j orc.

Hence : W = the sum of all the co-efficients, except the

first of the terms of an equation, whose roots are ee ey
: nm n

/

— , &c, multiplied by u ; but by the conditions of the pro-

Y¥2 blem

172 AN EXAMINATION OF SOME QUESTIONS

blem, p of the quantities a, b, c, are even, and g of them odd

numbers, or p of the roots of the equation are of the form =

and qg of the form +1 and the equation itself is the develope-

”
ment of (« -- aiF (« — =)! =O;

the sum of all its co-efficients except the first may be found
by making a = 1, and subtracting unity, this gives

tw=(+) G—)—w

—1
or W=n(**"y CG) u—nu; (6)
if p= q this becomes
Wis — u—nu (7)

if n =1, whatever be the numbers p and gq, the loss will be
equal to u (unless at the same time g= 0), for in that case as
soon as the first unfavourable event happens, the player loses
not only all he had previously won, but also the sum w be-
sides ; and since, by the conditions of the play, he must sub-
tract from wu the nth part of all his former loss, which since
n =1 is —u, his next stake must be wu — uw, or zero; so that in
fact if n = 1, the first unfavourable decision terminates the
game. sae
I shall now proceed to show how a similar mode of reason-
ing may be applied to cases where the number of events which
happen at each step are more than two.
Suppose a person draw a number of balls in succession from
an urn, containing balls numbered 1, 2, 3, 4,.. %, there being
many of each kind: he begins by staking the sum w, and fi he
raw

CONNECTED WITH GAMES OF CHANCE. 173

draw a ball marked one, he receives n, times his stake, if the
ball be marked two, he receives n, times his stake, and so on.
The next stake is thus regulated, supposing the ball Jast drawn
to have been marked i, he adds to the. last stake the sum v7; :
any of the numbers n, n,, . . may be negative, if he has drawn
p balls marked n,, g marked n,, r marked n,, and so on,
what is the amount of his winning ?

Let a, B, y,-.. be the Ath roots of unity, the expression
S.— a+ eet oy+..
ine k

is always equal to zero, except when a is a multiple of k; also
let
= nN, Sz + nN, Sa41 +n, Sate +..+%7, Sath—1 +
then P, will in every case reduce itself to one of the quantities
Ty Noy Mey + © © NM,
With the aid of these considerations, we can express the
amount of the stake at any particular step; his first is u, and
whatever be the kind of ball drawn, his profit is always ex-
pressed by wu P., according to the form of a. In consequence
of this first determination, he adds to u the quantity vP,,
which sum u+vP, forms his second stake; the number of
the second ball determines the amount of his second profit,
which may be expressed thus :
(u+vP.) Ps,
without at all determining the form of a, the third stake will
be ut+vP,+vP, and the profit arising from it is
(ut+vP.+vP,)P.;
that in the fourth event is
(utoP.+vP, +uP.) Pa.
the

174 AN EXAMINATION OF SOME QUESTIONS

the sum of all the profits will be
uP,
uP, + c(P.) Ps
uP. + v(P. + P;) P.
uPa + v(P. + Ps + P.) Pu
uP. + 0(Pa + Ps + P. + Pa) P..

It is easily perceived that the co-efficient of uw is equal to that
of the second term, and the co-efficient of v is equal to that of

thethird term of the equation

(a +P.) (@+Ps) @+P.) @t+Pu)... = 0;
but of the quantities * P,, P,, P.,..p are equal to n,, ¢ are
equal to n,, r are equal to n,, &c. this equation is there-
fore
(wn )? (a+n,)! (a+n,)... = 0;
and the co-efficient of the second term, in its developement,
is .
ON Ud OW? NFR tes
whilst that of the third term is

».p—l g—l r.r—l
P-F——n,? + UE n° + 5m, +--

so

* This notation has been employed by Mr Herschel, in a paper in the Philo-
sophical Transactions for the year 1818 on circulating functions.

CONNECTED WITH GAMES OF CHANCE. 175

so that the whole profit is

W=u(pn,+tqn +rn, +...) +0 es an: +...

+ Fan, + FE nn, +..} (8)

in the case of n, = 1, n, = —1,», = 0. This formula re.
duces itself to (1).

Supposing the urn in the last question filled with the same
balls, and a person drawing out one receives n,, ,, n,,..
times the sum w, according to the number of the ball drawn;
and on the second drawing he receives n,,,,7,,.. times
the sum of w+ the profit by the last drawing: and generally
on extracting any ball he receives n,,,,”,,.. times the sum
of u- the amount of the profit on all the preceding events,
if the number of times each of the balls marked 1, 2, 3, .. are
drawn, be respectively denoted by p, g, r, . . what is the whole
profit ?

Adopting the same notation as in the last problem,
P, = 7, Sa + nm, Sopi + ; Saye+... will represent either
n,, 1, m,,..- and the first profit is wP., the second is
(u+u P.) Ps; that in the third is(u+uP,+uP,+uP.P)P.,
and the sum of all the profits is

u PR,

uPs+ uP, Ps

uP. +uP,P.+uP, P.+ uP, P; P.,
&e. &e. &e.

On

176 AN EXAMINATION OF SOME QUESTIONS

On comparing this with the fourth problem which was solved,
it appears that

W=wx the sum of all the co-efficients except the first
of the equation (w+ P,) (c+ P;) (e+ P.)... = 0,

of W721 Pat © il es) ob. as

but p of the quantities P., Ps, P.,... are equal to n,, q of

them to n,, r of them to n,,... This equation, therefore,
becomes
W=a(btn,)P Gano te, re. ite (9)
3 1 fe Paes.
itt, n,=— 5, =0, and w=nu. This coincides
with (6).

As an example, suppose an urn filled with balls of three co-
lours, white, black, and red, and that the person who draws
them out may name any sum he chose prior to each extrac-
tion; if he draw a white ball, the sum he named is paid to
him ; if a black, he loses one-half of it; and if a red one, he
loses one-third of that sum. And suppose he regulates the sum
named in the following manner, beginning with naming u
whenever he has drawn a white ball, he adds the whole of his
previous winnings to the sum u; but if he has drawn a black
one, he adds only half his profits to the sum uw; and if the ball
last extracted from the urn was red, he adds one-third of all
his profits to the same sum wu. He has drawn out p white, ¢
black, and r red balls, what is the amount of his profit or
loss ?

In

a Se

CONNECTED WITH GAMES OF CHANCE. 177

i 1 1 Es
In this case n, = 1, n, =— 5,% =—9.™% =", =--=0
and we have
aPaeat
Was 2
Vere a a
ST 3" 3

The questions examined in the preceding pages afford an
instance of the immediate application of some very abstract
propositions of analysis to a subject of constant occurrence,
which being as far as I have been able to discover, hitherto
untouched, and also requiring reasoning of rather an unusual
nature, I have preferred treating in particular instances, in-
stead of investigating it in its most general form. The prin-
ciples on which similar problems should be attempted, are
first by means of some combinations of the roots of unity to
represent the stake after the decision of any number of events,
and then by means of any known theorems respecting the
roots of equations, to ascertain the sums of the series which
present themselves in the result.

‘eet he:
te

XI. On the Radiation of Caloric. By 'The Reverend Tuomas
Crompton Ho ianp.

1

(Read Feb. '7. 1820. )

Tue various facts concerning the radiation of caloric pre-
sent a very interesting subject of inquiry, and various theories
have been formed, with a view to their explanation. The
principal difficulty has been to explain the facts of the appa-
rent radiation of cold. The most simple theory with respect
to these, is that proposed by M. Prevost of Geneva. He sup-
poses, that all bodies are always radiating caloric in proportion
_to their temperature, and that those surfaces, which radiate
least, make up for the deficiency, by reflecting most; so that
the combination of reflection and radiation from any surface,
when in equilibrio with the surrounding bodies, is the same.
When a body is heated, its radiation is increased, and there-
fore, when placed near a thermometer, it radiates more to the
thermometer than it receives from it, and therefore elevates its
temperature. When, on the other hand, a body is cooled, it
intercepts from the thermometer near it part of the radiation
of the surrounding objects, and it radiates less than it re-
ceives. The thermometer must therefore sink. The princi-
pal objections that have been urged against this theory, are de-

zZ2 rived

180 ON THE RADIATION OF CALORIC.

rived from the apparent reflection of cold by concave mirrors ;
and from the circumstance, that a blackened surface, which,
when heated, produces more heat than a polished one, when
cooled, produces more cold, though in the latter case it must
be supposed to radiate most caloric. In THomson’s An-
nals, vols. v.—viii. are given various papers by M. Prevosr and
Mr Davenrort, which appear to me to afford a complete ex-
planation of these facts; but, from the conciseness of their
statements, and from their not being illustrated by calculations
or diagrams, they are not easily comprehended, and appear
not to have been generally understood. Mr Davenporr’s
statement is, “ Fill a canister, of which one side is polished,
and the other black, with a freezing mixture. Has not the
black surface lost a part of its intensity of radiation? This
cannot be denied. Has the polished surface lost its power of
reflection? The answer must be in the negative. It follows
then, that unequal diminutions have been imposed on those
powers of returning heat to the thermometer, which before
were equal. The radiating surface has lost more than the
reflecting one, and its thermometer receives less return, than
that on the reflecting side.” This appears to me a satisfactory
explanation ; but from the difficulty of comprehending the rea-
soning, without reducing it to calculation, it seems not to have
been generally understood. Dr Morray, after admitting both
the premises, objects to the concluion. He says, “ The clear
surface has also had its intensity of radiation proportionally re-
duced. And at any temperature, the blackened surface ra-
diates more caloric than the clear surface does at the same
temperature. The former, therefore, returns more caloric to
thethermometer than the latter, or at least, allowing all the
effect that can be ascribed to difference of reflection, no cause
is assigned why it produces a greater degree of cold.”

From

—_

|

ON THE RADIATION OF CALORIC. 181

From considering the subject, before I had seen Mr Daven-
port’s papers, the following explanation occurred to me. It:is
in principle the same with his, and only differs from his, in be-

ing, 1 think, more easily understood, and in showing from the

calculation, how Dr Murray’s objection maybe completely obvi-
ated. Plate XI. Fig. 4, let P be a polished body, and B a black
one. Let their combined powers of radiation and reflection,
when in equilibria with the thermometer, be represented by 1.
In P, let the reflection be 3, the radiation 3. In B, let the re-
flection be 1, the pabiseoelé Now, it is only the radiation
which can Be affected by a their temperature. Let
their temperature be raised, till their radiating power is

, sonpled:! Then, % be Il ea

dunk | kati ek) Eee he, ore
. reflects, I radiates, fs, fences above the equilibrium, ;
4 = 2 . 3

4

B, tne ae

£ 6.
oh”

Now, as it is only the excess above the equilibrium that can
affect the thermometer ; ; B, which radiates 3 times as much as
P, will affect the thermometer 3 times as much. Now, let each
body be cooled, till it radiates only } as much as when in equi-
librio. Then, ;

- - J - ¥g

oe oui Baie 2 We Bae bt See ee ee
reflects, “headin lau, {def from the equilibrium,
B- ~- -}
But it is the defect from the equilibrium only that can affect
the thermometer ; and therefore B, which, when heated, pro-
duces 3 times as much heat as P, when cooled, produces 3
times as much cold; though in all cases it radiates 3 times as
much

alm

- - - - - =- - - - =
i

182 ON THE RADIATION OF CALORIC.

much caloric. This reasoning will be much confirmed, by
considering the circumstances which will occur, when the sur-
face of the thermometer is supposed to be changed. Fig. 5,
let P be a thermometer with a surface of polished metal, and
B a blackened thermometer, and their radiating and reflecting
powers as above. Let A be any body. Then while they are

3

Pre hae: 2 o%
all in equilibrio, A acts as 1, of which | rete, radiates, i ‘

PI 3

a

Now, if the temperature of A be changed, it is the reflection
from the thermometers that will be proportionably altered ;
their radiation will remain the same till their own temperatures
are changed. Let A be heated till its action is as 2, Then,

Po. fe) - ape en Lap a= eee
reflects, | radiates sum, defect from 2, }.
2 o3 4 a 1i 3

Fey See AEG Aa © | aad

4

- - fai

But it is this last quantity, namely, the difference between the.
action of the thermometer and that of the heated body, which
operates to raise the temperature of the thermometer ; and
therefore, that with the blackened surface will shew 3 times
the sensibility to heat that the polished one does.

Next let A be cooled till its action is as 3. Then,

P-- g) ---H- -
reflects, + radiates, ¢ sum,
3

7
Bight) El les cath ah bsbd

excess above +,
3
Sar aii,

Or
———
1
1
'
'
!
O|—
——

But it is this last quantity, the difference between the action
of the thermometer and that of the cold body, which affects
the temperature of the thermometer, and therefore the black-

ened

2

ee

ON THE RADIATION OF CALORIC. 183

ened surface will be 3 times as sensible to cold as the polished
one. Braet |

Thus this theory explains why those surfaces which ra-
diate the most caloric, produce the greatest cold when cooled,
and are most sensible to the impressions either of heat or cold
from surrounding bodies. It is equally applicable to the appa-
rent reflection of cold. In Fig. 1, 2, 3, let DEFG be the sec-
tion of a room. In Fig. 1. let the thermometer T be near a
plane mirror AB. This prevents the radiations from the wall
DE from reaching T. But this is compensated by its reflec-
ting on T a part of the rays which proceed from the space
HGFI. Of these the eold body C intercepts the portion KL,

and therefore the plane mirror will increase the cold, but in a

very minute degree, in the proportion of KL to HGFI.
Fig. 2., AB is a concave mirror. This also intercepts the same
radiation DE, and, if the thermometer be in the focus of pa-
rallel rays, the mirror reflects on it rays proceeding from HI,
and these are rendered equivalent to those from HGFI in the
former case, because the plane reflects only some of the rays
on T, while the concave mirror concentrates at its focus all
the rays from HI. But when the cold body is introduced, it
intercepts the same space KL as before. The degree of cold,
therefore, from one concave mirror, should be as KL to HI,
that is, evidently much greater than in the last case. This is
supposing the thermometer to be placed exactly in.the focus
of parallel rays. But if it be placed so that all rays proceed-
ing from C would be converged upon it, then only such rays
as MCB, which pass through C, will be reflected on T. When
the cold body is introduced at C, it will therefore intercept all
these rays, and a much greater cold will be produced.

Fig. 3. represents the action of 2 concave mirrors. Here
AB intercepts the radiation from DE, and KL that from HI,

and

184 ON THE RADIATION OF CALORIC.

and it also prevents any of the rays from HI reaching the
mirror AB. This is compensated for, because all such rays,
as MCL or NCK, from MDEN which pass through C,
and fall on KL, are by it reflected in parallel lines to AB, and
by the second mirror are concentrated at T. But when the
cold body is introduced at C, it intercepts the whole of these
rays, and therefore great cold is produced. This explanation
of the apparent reflection of cold is precisely the same with
that given by Mr Davenrort ; but, from his having attempted
to express it without using diagrams, his statement is not easi-
ly understood.

In this paper, therefore, the part which is absolutely new,
is that which relates to the sensibility of different surfaces to
the impressions either of heat or cold. I hope, however, that
I have succeeded in making the other parts more easily un-
derstood than former writers have done. This explanation of
these facts on the theory of all bodies always radiating calo-
ric in proportion to their temperatures, appears to me to fur-
nish a decisive confirmation of that theory, as it shows, that
the circumstances which have been supposed to be the strong-
est objections against it, are in fact necessary consequences
from it.

Fig. 4,

ON THE RADIATION OF CALORIC. 185

Fig. 4. i"
Ta ae B
In aequilibrio. When heated.

- z P x t : i, i F; 1; fi bs i . z
vend : radiates, ‘ reflects t radiates t sum *y excess above the equilibrium
LD SOAS CARES So 4 REE RRR ais pik i aeamaae amelaala

When cooled.
A I AMIS SN ARE OSE A Ra eee
reflects \ sate ; sum ‘i defect from the equilibrium
IIA Be yum od Spe Dutie Ms a hs dat Es 5
Fig. 5.
| iad peti
oe ee oO
P B
In equilibrio.
Bee SYitien:x, wh
reflects radiates A acts as 1
“cpl ade 3 ie bata:
When A acts as 2.

SAD Ss Pottian te ee Mapa fel g z z
Tai { reflects radiates sum defect from 2
very te Deh awed : :

a es Soa ' When A acts as 1. ; ‘
On 4 p ; -
x ee Sy! eo Oa pdg : }
o reflects radiates > sum excess above 3
é oo ape ees eae I festa : ;

Vv Le Ix, P I A a XiL

th ,
5 ik es
Lr tS
c ¥ a SS ae
an “pouting aM
ay ; + le
% .— G £0;
: +
oF ¥
We
oN Mp
>. > tae
Tae
; f.

Pe ra
: ;
ij »
“tes
1
)
HX

XII. Notice respecting a Remarkable Shower of Hail which
fell in Orkney on the 24th of July 1818. By Patrick
Nett, F.R,S.E., F.L. S$. & Sec. Wern. Soc.

_(Read March 1. 1819.)

Tue notice which, at the suggestion of Dr Brewster, is
now, to. be laid before the Society, respecting a remarkable

‘shower of hail which lately fell in Orkney, has been drawn up

partly from conversations with Ricuarp Carrunsss, a plain but
intelligent country man, who possesses a small farm at Hunday
in the island of Stronsa, and whose. property suffered severe-
ly from the ;shower; and ‘partly from subsequent. correspon-
dence with the Reverend Witi1am Taytor of Stronsa, whose
house olay: in the, track of the cloud,: and with Mr Roser
Linpsax, Student of Divinity, who had ‘an opportunity of wit:
nessing the effects of the hail at Lopness, on the néighbouring
island-of Sanda, when the shower was nearly exhausted. They
agree in all important particulars; but even at the risk of
some Mee ot their own Gree, shall, as: often as ash he
- employed ys

“The. morning of the 24th of J Ae 1818, was, in Orkney, clear
and warm, with a slight air of wind at due south. About mid-
day the atmosphere became overclouded, and somewhat agita-
ted; the wind about this time veering a point or two to the

aa 2 . west

188 ON A REMARKABLE SHOWER OF HAIL

west of south, and occasionally rising into a breeze. Between

twelve and one o'clock, thunder and lightning began; and

after these had continued with little intermission for about an

hour and a half, a very dense jet-black cloud forcibly attracted

attention by its foreboding appearance. Mr Tayzor was in

the upper part of his house when he first’ observed this black

cloud, apparently rising from. the sea, at the distance, he

thinks, of about-five or six miles, It then seemed of no great

dimensions; but its magnitude was gradually developed, as it

approached steadily, and apparently with increasing velocity,

from the southward, in a direct line toward the centre of
the island. It now assumed a dismally ominous aspect,

and occasioned a considerable degree of darkness. The

lightning became proportionally more vivid, and the peals of
thunder were tremendous. Mr Taytor remarked one flash of
lightning tobe not only brighter than the rest, but to exert a

more extensive influence on the cloud, which seemed. as if
cleft asunder, and presented a momentary opening of the

prospect between the Mainland of: Orkney and the island of
Stronsa. » The thunder-bolt on this occasion seemed to strike -
the surface of Stronsa Frith in the mauuer of a ae yer body

dashing into the sea.

Ricuarp. CairHNEss was engaged in the nee of kelp
on the shore, when he perceived the cloud advancing fast
towards his: own: farm-steading. He immediately hurried
home. At this time the wind began to rise; the sur-
face of the sea was greatly ruffled; and darkness like that of
night threatened to come on. Just as he reached his house,
the cloud overtook him. The lightning was now instantane-
ously followed by noises, like the firing off of “ guns in Stron-
“sa Caves.” Hailstones of very uncommon magnitude began
to fall. The first large hailstone which Mr Cairuness saw,

came

WHICH FELL IN ORKNEY. 189

came through the glass of one of his windows, and struck the
floor violently : it was, to use his own phrase, “ really like a
* oose-ege.” In two or three minutes more, the wind in-
creased almost to a hurricane; and instead of hailstones of the
usual shape, “ pieces of ice,” of almost all forms, were preci-
pitated with the utmost violence. Not only was every pane
of glass in the windows of the house, fronting the south, speedi-
ly broken, but the cabbage-plants in the garden immediate-
ly adjoining, and which could be seen from the windows,
seemed as if suddenly cut over, and strewed about the
ground*. The “ clattering noise” of the hail which fell in the
sea at this time, is described by Mr Carruyess as quite terri-
fic; and, having been induced by this strange noise to look
particularly in the direction of the sea, he adds, that not only
did the hail keep the water as it were boiling, and covered
with white foam, but he repeatedly saw the lightning striking
from the cloud into the sea, and the water, where it was
struck, “ dashing up as high as masts of ships.” The light-
ning was not forked or zig-zag, but rather in the form of balls
or/masses of fire. The whiteness of the foam of the sea was
rendered more evident, and the brightness of the fire more in-
tense, by the contrast of the surrounding darkness...

The farmer and his family had not recovered from the con-
sternation’ excited by such an extraordinary event, when the
wind and hail ceased, and the sky began to clear.. When they
ventured to look’ abroad, the fields presented a scene of per-
fect desolation. In the “ close” or farm-court, surrounded by
offices, the hailstones had accumulated, and lay a foot and a half
deep ! In the open fields, although they did not. perhaps exceed

‘3 enw jadw , ‘hie

rhita 3

| * These cabbages, it may be remarked, were of the large red Aberdeen sort,
well known to be the strongest and coarsest of the tribe.

190 ON A REMARKABLE SHOWER OF HAIL

the half of this depth, yet not only were the crops of every kind
utterly beaten down, but not a vestige of them was for some time
to be seen. The astounded farmer saw only “ fields of rough
“ ice.” All this destructive change had been accomplished
in less than ten minutes. : —

Alarmed by the “ horrid cries,” very different from the usual
bellowing, of some black cattle, which had been grazing on
pasture-land at some distance, Carruness attempted to wade
out among thethailstones in the direction of the cattle. The
“ loose ice,” he says, slipped below his feet, and sometimes
reached to‘his knees. In this way his legs were so much cut
by its sharp edges, that he was soon obliged to desist, and
to wait till the ground began to appear, by the melting
of the hail. The pieces of ice he describes as of various
shapes: most of them were round like eggs ; many were flat-
tened, and not unlike “ thick clumsy oyster-shells ;”. some
were nearly smooth on the surface, others very ragged and.
jaggy. Some of these appearances probably arose from the
hailstones being ‘partly dissolved. Mr Taytor likewise re-
marks, that some“ ‘were as finely polished:as marble-bowls,
“« while others were irregular, and apparently made up. of pie-
“ ces of conglomerated ice.” Mr Tayior regrets that he did
not immediately weigh some of the Jargest balls, before they
began to melt ; for he was unluckily not: provided with a gra-
duated jar, with which to ascertain the liquid contents. He
adds, however; that-he:“ had presence of: mind to measure
“ some of the largest lumps,” and that several of them, were
about six inches in circumference. Mr Carrungss thinks, that
the largest pieces of ice which he lifted, might weigh from
four ounces to nearly half a pound : but he adds, what was ex-
tremely natural, that, at the moment, he thought only of the

damage his farm had suffered, and it never entered into his
mind

WHICH FELL IN ORKNEY: ~ Y9I

mind to weigh the instruments of destruction. He describes
the hailstones as being generally of a greyish-white estou, not
unlike fragments of light-coloured marble. .

- The terrified black cattle and .horses, which had kan
their tethers, and been observed, at the beginning of the fall
of hail, running violently backward and forward, galloping and
flinging, had now collected together in a herd, CarrHness at
length made his way to them through the half-melted ice; they,
still trembled exceedingly ; some of the horses had lain flat down
.on the grass, with their heads stretched out ; and all of the ani-
mals were more or less cut, and bleeding. Some of the weaker
horses, the farmer says, will never recover: the milch cows,
he adds, were “struck yeld,” or gave no more milk, and in-
deed would not suffer the people to iii to milk them any
more. ;

On the links or agp at some diestanhegs Saas Chmatobes: $
house, aJarge flock of tame: geese had, been feeding: these,
he remarked, seemed to remain motionless on the turf;
and on proceeding to the place, he found no fewer than sixty
wholly deprived of: life ;: a few were still living, but so much
injured, that all of them: pined away and died in a short time.
Some:of these poor: birds had their bills split; others had an
eye struck from its socket, and hanging by the nerve ; and the
brains of some were sarely vs evo out : mpi had either a leg
or a wing broken. «|

The weather being warm, the i ice soon diss sbatesd: 3 and
CarTaness’s fields, which, ‘less. than an hour before, had been
covered with corn-crops * just beginning to come into ear, and
superior: in laxurianee” to what had been seen in Orkney for

hooky Tere ioe ap ashes -; Wi, % many

Lind voulserge abe 3) 4, BA i95¢, Leu MAW ;

phainuow

- * Grey oats, Avena neeee L.; ot oo a meet variety of Herein te-

trastichon ; which are the only kinds of white crop cultivated with success in these
islands.

192 ON A REMARKABLE SHOWER OF HAIL

many years, seemed (to use -_ farmer’s sa to have
been “ absolutely plowed black. .

It may be remarked, that aw sudden endutei of cold,
and consequent congelation, had taken place at a considerable
elevation in the atmosphere, for, as Mr Carruwess observed,
the hailstones must have fallen with great force, since many
of those which fell first were sunk in the corn-fields from three
to four inches deep; and even in the firm old pastures, each
of the first-fallen hailstones had made a hole in the sward
exactly of its own size and shape, to the depth generally of
about two inches. In some of these holes the balls of ice lay
unmelted, long after the others had disappeared. Mr Taytor
says, that the surface of the ground all around his house
was every where perforated as with the “broad point of a
“ country man’s staff ;” and it retained this Maori fark se-
veral days.

It may further be remarked, ‘that the fakes hii fallen
not only from a great height, but, owing to the strength of the
wind, at a very considerable angle. Mr’ Taytor was obliged to
flee from one room to another in his house, in order to avoid
the fragments of glass, which were driven to the farther side
of the apartment. In Mr Taytor’s bed-room, the wash-hand
bason, although standing at some distance from the window,
was shivered in pieces by a hailstone. tf

As the ice melted away, great numbers of small birds, parti-
cularly skylarks, stares or starlings, corn-buntings, and chacks
or wheat-ears, were found dead, and were collected “ in heaps”
by the boys belonging to Carruyerss’s farm... On the. shore,
near to a point called Torness, were observed’ numbers of
rock-pigeons, hooded crows, tysties or guillemots, and stock-
ducks or mallards, which had been killed at sea by the hail,
and were left by the receding tide. Many wounded gulls and

_ picktarneys

P Pa

ee SS — SE =e

WHICH FELL IN ORKNEY. 193

pictarneys or sea-swallows, were seen floating on the sea, oc-
casionally attempting to fly, but unable to raise themselves.

» Owing to the fortunate circumstance of the: thunder: and
lightning having for some time preceded the great fall of hail,
the people at: workin the fields, and on the “ kelp-shore,” in

the track of the cloud; had all taken shelter. One boy alone,

named Perer Stevenson, suffered from exposure: he was at a
distance from any house when the hail began ; he threw down
a bundle which he was carrying, and ran towards a projecting
it, he received a severe’ blow on the back of the neck, which
stupified him, and: produced:.a ‘contusion, from the’effects of
which he had not recovered after the lapse of six months.
Four men in a boat, at some distance from land, were exposed
to a part of the shower, and had their hands much cut and
bruised by the hailstones: Had they been subjected to its full
violence, ‘they: would probably have:perishedi) °°

It does not appear that: the electric fluid had any share in
killing the geese or other birds, at least no’marks of discolora-
tion or singeing were observable on the feathers, and the pal-
pable blows which the animals had received, were fully suffi-
cient, to, a¢count» for their death. The cows being “ struck
“. yeld,’.as CAITHNESS expresses it, seems a curious circum-
stdnce);. it is ascribed. by him to. the dreadful fright they got.
The wounds received by the cattle and horses were all evident-
ly inflicted by the hailstones: It is proper to add, however,
that, in. some ‘places, Carruness observed the’ surface of the
pasture-grass ‘to. be » much discoloured and scorched-like ;
andva .good deal’ of the broken straw’ of the’ grain-crops
likewise“ coloured white by the fire, as if it had been sudden-
“ly ripened.” Mr Tayior informs’ me, that when he first
went abroad, immediately after the cloud had passed over, he
NOL. IX. PAL Bb was

194 ON A REMARKABLE SHOWER OF HAIL

was not only sensible of a sulphureous smell, but that it was
so strong that he had speedily to return for a draught of water,
in order to remove the disagreeable sensation in the throat.
He observed that the cattle afterwards avoided certain scorch-
ed parts of the pasture, which did not recover their verdure
till repeated showers had refreshed them.

Ricuarp CairHNeEss was not the only farmer whose crop and
farm-stocking were injured. Grorce Fovris, tenant of the
farm of Holland, a possession of much greater extent and va-
lue, was equally involved in the devastation. This farm, ly-
ing to the southward of Hunday, was of course to the wind-
ward; and Mr Carrxnxss told me, that the “ dismal yells” of
Fouuis’s wounded cattle, on the high grounds between the two
farms, and which reached him, notwithstanding the noise of
the hail, produced a feeling of horror which he could not de-
scribe,—but that the cries seemed still to sound in his ears.
These two, however, were the only farmers who suffered se-
vere damage ; although many families of cottars, or humble de-
pendants, had their patches of corn and potato crops com-
pletely destroyed.

The meeting-house and manse of the Reverend Mr Taytor
were in the line of the cloud. In both, the south windows
were wholly shattered, not only the glass, but the wooden as-
tragals being broken. Mr Tayzor observed by his watch the
duration of the violent wind and heavy hail, and states it to
have been little more than eight minutes.

Both Mr Tayzor and Mr Carrungss concur in describing
the thick layer of ice or hail as forming a tolerably well-defin-
ed belt across the island, in a direction from S.S W. to N.
N E,, passing through the centre of the old parish of St Nico-
las. This belt, they think, might be about a Scots mile broad,
—perhaps.nearly a mile and a half English; and beyond this

line,

0 eS

WHICH FELL IN ORKNEY: 195

line, on each side, the ground appeared “ spotted with ice,”

to the extent of about half a mile more. In confirmation of
the accuracy of their observations regarding the extremely lo-
cal nature of the shower, it may be mentioned, that persons
who had been employed the whole day in digging turf in a
peat-moss near Rothiesholm Head, which supplies the island
with fuel,—at the distance of little more than two miles in a
direct line westward from Carruness's house, though conside-
rably to the southward,—were wholly exempted from its in-
fluence, and wondered very much when, in passing homewards
in the evening, they witnessed the devastation which had been
produced within the track of the hail. They had indeed ob-
served a very thick black cloud shooting past the high rocks of
Rothiesholm Head in the afternoon; they had seen bright
lightning, and heard loud thunder ; but they had not been touch-
ed by the hail. Thesame thing happened to the eastward ; the
farm of Cleat, situated only Sean a mile and a half distant in
that direction, having scarcely been affected by the shower.
But even to the heard (the direction from which the cloud
came,) the range of the storm was very limited. The penin-
sula of Deerness, belonging to the Mainland of Orkney, was
directly i in the line, about seven or eight miles to the S. S W. ;
yet it remained untouched. Mr CaitHness indeed beating
that he had spoken to some “ Deerness men,” who were that
day fishing off the Moul Head, the most northerly point of
Deerness, and who told him, that they observed the cloud
thickening and blackening ; as it rolled on towards Stronsa.

It would appear, therefore, that the accumulation of electric
matter came to a crisis over the sea, at the distance of about
three or four miles only, to the S. W. of Stronsa. The cloud
swept up Rothiesholm Bay, and crossed the island i in the way
already described. When nearly in an exhausted. state, it

Bb 2 touched

196 ON A REMARKABLE SHOWER OF HAIL

touched the north-east corner of the island of Sanda. Mr
Linpsay (already mentioned) happened at this time to be at
the house of Mr Srrane of Lopness, situated in that part of
Sanda. Although the main force of the shower ‘was now
spent, the effects were still formidable; -a good deal of the
glass in the windows. having been shattered. © Ais the cloud
was passing off, it occurred to Mr Linpsay to observe the state
of Mr Srrane’s barometer; and he found the mercury sunk
so low, that it was HEE EEE to mark its place on the wooden
frame, the scale, as is not uncommon in old barometers con-
structed for this country, not being graduated. lower than 28
inches. Lieutenant Barxie,’ R.N. has since extended the
scale, and found Mr Laypsay’s mark to indicate 27.76. When
the cloud had’ completely passed, Mr Linpsay, having gone
into the garden, observed that the “ cabbages were paieiortad
as if musket-bullets had been shot against them.”—* About
an hour afterwards,” he adds, “ I picked up some that still re-
mained undissolved, and found that they measured 1.2,th inch
in diameter. They were for the most part of a spteroitti
form, consisting of a nucleus resembling common hail, occu-
pying about oleae of the diameter, encrusted by a coating
of transparent ice. Some of the stones, however, were irre-
gularly formed into a sort of crystallized mass.” Mr Srranc’s
house is situated about twenty feet above the medium level of
the sea. ,

The last remains of the shower, it may be added, were
slightly felt on the south-east point of the island of North Ro-
naldsha.

The whole extent of the course of the hail-storm, from S. W.
to N. E., was thus little more than twenty miles ; and, as near-
ly as I can learn, it travelled this space in less than half an
hour, or at the rate of a mile in a minute and a half, as it
required between eight and nine minutes for its passage over

Mr

EN ee

WHICH FELL IN ORKNEY. 197

Mr Tayzor’s house. The cloud, when at its highest pitch of
accumulation, appears to have extended at once between’five
and six miles in Leet. ASO stot i

In the afternoon the sky was clear, the wind hushed, and
the air warm and genial.

Being aware that at all the Northern Light-houses, registers
of the state of the barometer and thermometer are regularly
kept, (an attention to the interests of science which is high-
ly praiseworthy,) I applied to Mr Srevenson, Engineer to
the Commissioners, for an extract of the register at ihe light-
house at the Start Point, or eastern extremity of Sanda;
which he most readily granted me. It appeared that the hail
had not at all touched the light-house, although, as already
mentioned, it had broken the glass of the windows of the
house of Lopness, not an English mile distant. Mr Cuarzes
Nisser, the principal light-keeper, writes thus to Mr Stevenson.
“« I was at work in the field, putting up some hay at the time:
the sky was very black to the south-west, with thunder. Ina
short time rain began to fall heavy, with a sharp breeze of
wind, but not the least appearance of hail. I was therefore
surprised 1 the next day, when I heard of the mischief done by
the hail at Lopness. The fall of rain at the far m-house of Se-
. libuster” (situated as far to the west of Lopness as Start Point
is to the east), “ was very heavy, and. was followed by some
hail.”

The following is an extract from the Start Point register,
from 20th to 30th July 1818.

STATE

198 ON A REMARKABLE SHOWER OF HAIL

Strate of the Barometer and THerMomMeTEeR in the Start Point
Light-house, the instrument being situated a hundred feet
above the medium level of the sea.

>

Breeze
do.
Light airs

Streit

From this extract, it appears, that at 8 in the morning of
the day of the shower, the mercury in the barometer stood at
29.68, and that on the following morning, at the same hour,
it was at 29.72. ‘The effect of the hail-storm, in producing,
for a short time, a more attenuated state of the atmosphere,
was therefore very remarkable; the mercury, as observed by
Mr Linpsay, having sunk two inches, or to 27.76, during the pas-
sage of the cloud, or immediately after its passage.

Such are the particulars of this remarkable meteoric occur-
rence which have come to my knowledge. I am aware, that
accounts of similar hail-storms are upon record, particularly in
the Philosophical Transactions. But I have not thought it ne-
cessary at this time to examine these, nor to institute any com-
parison ; my only object being to add to the stock of facts.—

For

Engraved tor the hoyal Socwly Trans? VoLIX. pagel99

SKETCH
evhibiing the extent
of the remarkable

Hail Shower

Mm
ORKWEY

July 24 1818.

on
ae ee

Westra

Lamb Head

housholi | NOPE ALY
Head nal Lor neds
iy G

2 : Rel2) 5 eS oh ee

Dear
Sound

oferse

CE LA opinsha

Drawn by 6. C Scot M? Stevensons Office

i
;

saan bali WHICH FELL IN ORKNEY. - 199

For the same reason, I have considered it unnecessary to ad-
vert to any of the hypotheses which have been suggested by —
philosophers, in order to account for such hail showers ; for the
sudden coalescing of the watery vesicles, and their almost si-
multaneous conversion into ice. 3

On the accompanying little Map, Plate XII., traced from
Morvocu Mackenzie’s General Chart of the Orkney Islands,
the track of the hail-shower is pretty accurately laid down,
and its very local nature is thus exhibited in a more striking
manner.

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XIII. Observations on the Mean Temperature of the Globe.
By Daviv Brewster, LL. D. F.R.S. Lonv. &
Sec. R. S. Eprn.

(Read February 7. 1820.)

Ir no provision has been made by the Great Author of Na
ture, for equalising the light and heat projected upon the dif-
ferent bodies of our system, we may consider the earth as re-
ceiving, from the direct action of the solar rays, a degree of
heat, intermediate between the condensed radiations sustained
by Mercury and Venus, and the attenuated warmth which
reaches the remoter planets. The heat which our Globe thus
acquires from its locality in the system, is again tempered by
the obliquity of its axis, and is distributed over the same pa-
rallels of latitude by its daily rotation. When the Sun is in
the Equator, his. rays, beating on the Earth with a vertical in-
fluence, impart to. it the full measure of their action; and as
his meridian altitude decreases, their intensity suffers a corre-
sponding diminution. The burning heat at the Equator be-
comes moderated in higher latitudes. In passing through the
temperate zone, it declines with great rapidity, and between
the Arctic Circle and the Pole, the rays of the Sun are ‘unable
even to temper the piercing cold which reigns in these inhos-
pitable regions.

VOL. IX. P. ee This

202 OBSERVATIONS ON THE MEAN TEMPERATURE

This gradation of temperature, so obvious to the sensations
of those who have visited southern climates, is still more dis-
tinctly indicated by its physical and moral influence. The
arid plains of a tropical climate, where vegetable life is almost
extinguished by excessive heat, gradually shades into the more
luxuriant regions of the vine and the olive. The mild and
uniform temperatures of Spain and Italy, are again followed
by the variable climate, and the more verdant kingdoms in the
north of Europe. Then succeeds the region of blighted vege-
tation, where nothing can exist but the birch and the pine, and
the chain of vegetable life terminates in the hoary desolation
of the Arctic Zone.

The progression of climate is no less distinctly marked by
the developement of the human faculties, Indolent and im-
patient. of thought under the debilitating influence of a sultry
atmosphere, man begins to unfold his capacities as he is remo-
ved from the Torrid Zone. In more temperate climates, he
cultivates those faculties which do not lead to very rigorous
application ; and under the invigorating influence of a colder
sky, the mind attains that maturity of its powers, which fits it
for the most abstract and profound speculations. From this
region, distinguished as the seat both of ancient and modern
civilisation, the mind again sinks under the torpor of extreme
cold, and. the distinctive characters of our species disappear
among the diminutive inhabitants of the Polar latitudes.

The investigation of the mean temperature of the Earth,
connected, as it thus appears to be, with many interesting in-
quiries of a moral and physical nature, has not been pursued
with the same zeal as other branches of knowledge. Long af-
ter the invention of the thermometer, no attempt had been
made to apply it to meteorological purposes; and though, for
more than half a century, its indications have been registered

in

OF THE GLOBE. 203

in many parts of the world, yet. the observations with it have
commonly been guided by no settled principle, and are, there-
fore, frequently unfit for the purposes of generalisation. , Phi-
losophers: were satisfied with deducing a law of temperature
from theoretical considerations ; and. disdained the humbler
and more laborious: task of interrogating the mass. of facts
which had been accumulated by zealous:and active observers.
The first person who attempted to deduce from obser-
vation a general expression for the mean, temperature, at
all latitudes, was the celebrated astronomer. Tozras) Mayer
of Gottingen. «Assuming. thatthe heat varies as the
square of the sine of the latitude; he ,obtained the formula
T= 58+ 26 x Cos. 2 Lat., in which 58/is the mean tempera-
ture of 45° of north latitude, and 26° the difference between
the temperature of. that /parallel and the Equator... Mi Liexn-
TENBERG, ‘the editor of ‘Mayer’s posthumous works, applied
this formula to 13 observations of mean ‘temperature made. be-
tween the Cape of Good: Hope: and. Stockholm,,.and their
agreement was: considered at that time.to be remarkable... The
sum of all theerrors was 26°.8,0r a little: more than 2 on-each’
observation 5° but: ‘as the errors \in.excess amounted to 22.3,
while those in defect were only 4°.5, it should have: been ob-
vious that the formula ‘was: founded upon an incorrect. as-
; sumption. Ast Gin leupa. 9
The formula of: Baden “was: is temp hcilly: sloped “a Riasiash
in his able work ‘On the Mean. Temperature of the Earth; and
has been more recently brought forward, as connecting toge-
ther, “ in a most harmonious manner,” the results of distant
temperatures, although the fine series of observations, collec-
ted by Houmnotor, . had_ demonstrated its. inaccuracy, and pro-
ved, that even in the parallel of 63°, it erred in excess no
less than 9° of Fahrenheit.
cc 2 The

204 OBSERVATIONS ON THE MEAN TEMPERATURE

The beautiful memoir of Humsoxpr on the Jsothermal Lines,
or lines of equal temperature, and on the distribution of heat
over the globe *, has given a fresh impulse to this fundamental
branch of Meteorology, and will, no doubt, introduce a new
degree of precision into those loose and indefinite records of
temperature which have been so generally accumulated in
every part of Europe. In attempting to reconcile the for-
mula of Mayer with the observed results as given by this ce-
lebrated traveller, I expected to succeed, at least for the western
regions of the Old World, by the adoption of more correct
co-efficients ; but as I proceeded in the inquiry, I saw that the
principle of the formula was entirely irreconcileable with well
established facts, and I therefore sought for a law different
from the duplicate ratio of the sines.

In comparing the temperature of the Equator with that of
45°, and with that of the highest latitude in Humsotpt’s se-
ries, it was obvious that the cold increased much more rapidly
towards the poles than had been believed; and upon extend-
ing the comparison to the intermediate temperatures, I found
that the mean heat of any place was well represented by the
radius of its parallel of latitude, or, in geometrical language,
that the temperatures varied with the cosine of the latitude.
In expressing this law I have assumed 813° as the mean
temperature of the Equator, the very same number which
Humzorpvr has preferred as the mean of various results under
distant meridians. The formula therefore becomes

T = 812 Cos. Lat.
The

* This Memoir has been translated into English, and published in the Edin-
burgh Philosophical Journal, vol. iii, and iv.

OF THE GLOBE. 205

The following Table contains the observed mean tempera-
tures of thirty-one places, situated between the Equator and
the parallel of 70° of north latitude, together with the calcu-
lated results, as given by the preceding formula, and by that
of Mayes, in its latest form.

TABLE OF MEAN TEMPERATURES.

Observed Calculated ase Mayer’s | _.
Latitude. Mean Temp| Mean Temp. Difference. Rene Difference.
Equator, ......e.++ o 0 | 81.50 81.50 | 0.00 |/s4° 2 |2°7 4 |
Columbo, .........: 6.58 | 79.50 80.90 | 1.404 |\s3 .4|/3.9 4
Chandernagore, ...| 22.52 | '75 .56 75.10 0.46—||76 3 10.74—
(CANTON disa. cs: aan’ 30 .2 | 72,82 70 .56 1.76—|/71 1 }1.814
5 Funchal,........... 32.37 | 68.54 68 .62 0.08 + || 69 .0 |0.464
Rome, ........... +. | 41.54 | 60.44 60 .66 0.224 ||60 .7 |0.364
Montpellier, ....... 43.36 | 59.36 59 .03 0 .38—||59 .4 |0.044.
Bourdeaux,........ 44.50 | 56.48 57 .82 1.344 1159 .0 12.524
Milan, ....0.000.-+- | 45.28 | 57.19 58.28 | 1.104 |l57 .7 |o.594
10 Nantes,.............| 47.13 | 54.68 _ 55 .85 0.67+4 ||56 .10)1 424
St Malo,............ 48 39 | 54.14 53 .85 0.29 —|/ 54 .80) 0.66 +
Eeanisy auacus ae ttee 48 .50 | 51.89 58 .65 1.76 + ||54 .60)2.71 +
Brussels, ........... 50.50 | 51.80 | - 51 .A7 0 .33—|/52 .90)1 .10 +
Dunkirk,...........| 51. .2 | 50.54 51 .25 0.71 + |/52 70/2 164.
15 London,......... ..| 51.30 | 50.36 50 .'74 0.384 |/52 30/1 .944
Bushey Heath,..../51 3872] 51 .2 50 .58 0.62 —
Kendal,..........-4. 54.17 | 46.02 47 58 1.564 ||49 .8 13.784
New Malton,...... 54.10 | 48.28 47 53 0.75—|/49 9 |1.624
Lyndon,............ 54.34 | 48 .90 49 .37 0.474 /149 .5 |0.60 +
20 Dublin,............. 53.21 | 49.10 48 .65 0.45—|/50 .6 1.504
Copenhagen,.......] 55.41 | 45.68 45 .95 0.274 1148 6/2 .924
Edinburgh,.........| 55.57 | 46.23 45.64 | 0.59—|/48 32/2 .09 4
Carlscrona,....:....| 56.16 | 46.04 45.46 | 0.58—||48 .2/2.164
Fawside,............ 56.58 | .44 .30 44 26 0.04/47 .5 18 204
5 Kinfauns, .......... 56 .231|. 46 .20 45 12 1.08—||47 9 ]1.70+4
42 .26 41.57 0.69—||45 5 |3.244
42.08 40 .94 1.14—]/45 113.024
40 .00 40 .28 0.28 + 1144 .6 |4.604
33 .08 35 .96 2.884 ||42 119.024
33 .26 84.38 1.11+ |) 41 3 18.044

This

206 OBSERVATIONS ON THE MEAN TEMPERATURE

This singular agreement between the observed and calcula-
ted results, and the equilibrium of the positive and negative
errors, shews that the formula embraces the leading causes
which affect the mean temperature of the west of Europe.
The sum of all the positive errors is 13°.12, and the sum of
the negative errors 9.11; and their total amount is 22° 23,
which gives only an average error of xcths of one degree of
Fahrenheit upon each observation.

The results of Mayer’s formula give all the errors positive
except one, and their sum is no less than 70°.7, being 2°.3
for each observation. The error of the formula becomes so
great as 9 between the parallels of 60° and 70°, which
proves, in the most convincing manner, that the temperature
of 32, which Mayer assigns to the North Pole, is very far
above the truth, The formula which I have given above
makes the polar temperature so low as zero, or O° of Fahren-
heit’s scale, differing 32° from the preceding measure ; but the
circumstance of its representing with accuracy the mean tem-
peratures at very high latitudes, inspires us with some confi-
dence even in this extreme result.

In this state of uncertainty respecting the rebbabls tempe-
rature of the North Pole, and of the accessible parallels be-
tween 70° and 80°, I proposed to examine the most northern
meteorological journals, with the view of finding some general
rule by which the mean temperature of the year might be de-
duced from one or two months observations. I had previous-
ly communicated my formula to Mr Scorgsay, and requested
from him some information respecting the temperature of the
Greenland Seas ; and I had the satisfaction of finding, that this
subject had engaged his most particular attention, and that he
had actually deduced the mean temperature of the parallels of

76° 45,

OF THE GLOBE. ©" ” 207

76°.45',.and..78°, froma series of 650 wanton made by
himself, in-nine successive years *,

In the latitude of 76° 45' he, found. thes mean. teetnneaatuis to
be 18° xcsdths.. My formula makes: it 18° sccdths, ht on-
ly réodths ofadegree.

In the latitude of 78°, Mr — fait the mean tesbpie-
rature to be 16°x¢cdths. My formula makes it 16°rcodths, devia-
ting only résdthsi of a degree.’ Mayer’s formula makes the
mean temperature of these parallels above 34°, erring no less
than 33°, upon: both observations, ‘whereas the error of my for-
mula is only :th of a degree.

It appears, then, from the phileaine of didcut SbsBbediiGH,
that the temperature of the North Pole must be considerably
lower.than 16° rvcdths, and must therefore be more correctly
indicated by the new. formula than by that of Mayer. Mr
Sconessy has attempted, by a very ingenious analogical pro-
cess; to deduce the temperature of ‘the Pole from that of
76°45’. He considers the difference between the actual tem-
perature of that parallel, viz. 18.86, and the temperature gi-
vem by Mayer’s formula, or 33°.8’, as an anomaly produced by
the frigorific influence of the ice; and having found what this
anomaly should be at the Pole, he subtracts it from Mayer’s
polar temperature, in order to obtain the real polar tempera-
ture, which he thus’ finds to be 10. This result, however, is
‘obviously too’ great, upon Mr Scorsssy’s own principle; for
‘since Mayer’s formula errs greatly in excess in those parallels
where there is no‘ accumulated ice to produce an anomaly, it
must give at least an’ equal error in excess for the parallel of
16.45’. cob ier error in the latitude of 63° and 65° in Lap-
sed OW land

Mii

* This interesting investigation is now published, in Mr ScorEszy’s excellent
Account of the Arctic Regions, vol. i. p. 356.

208 OBSERVATIONS ON THE MEAN TEMPERATURE

land is 8°; and therefore calling it also 8°, which is far too
low for the latitude of 76° 45’, we have for the mean tempera-
ture, uninfluenced by the ice, 33°.8 — 8°.0 = 25°.8; from
which subtracting the polar anomaly of 21°, as computed by
Mr Scoressy, and we obtain 4°.8 for the mean temperature
of the Pole.

In the preceding paragraphs, we have compared the results
of the formula with the temperatures of individual places,
which must often be influenced by local causes. We shall
therefore compare the formula with the temperatures of the
four parallels of 30°, 40°, 50°, and 60°, which Humsoxprt has
deduced from a great variety of observations, and which he
considers as well established.

Lat. N. Observed Calculated Differences.
Mean Temp. Mean Temp.
30° 70°.52 70°.56 0°.04 +
40 63 .14 62 .43 0.71 —
50 50 .90 52.89 149+
60 40 .64 40 .75 0.11 +
ScoresBy 76 45 18 .86 18 .68 0/18 —
Do. 78 16 .99 16°95 0 .04 —

The differences between the observed and calculated tem-
peratures, both in this and the preceding Table, are frequently
owing to the circumstance of the thermometer having been
observed at two periods, the average of which does not give
the mean temperature of the day. The Reverend Mr Gor-
pon has found, from a series of very accurate observa-
tions, that the mean temperature will be obtained most cor-
rectly in this country, when self-registering thermometers
are not used, by observing at 10 o’clock in the morning
and evening ; and it is highly to be desired that this prin-
ciple should be adopted in all our meteorological journals.
Another source of difference arises from local causes, which

often

OF THE GLOBE. 209

often occasion a difference of temperature under the same la-
titude. In the case of Edinburgh, for example, the mean
temperature, deduced from Mr Prayrain’s observations, is
47.8 *, differing considerably from the formula, while the

VOL. IX. P. I. és pd mean

* As Mr Prayratn’s observations were made in Windmill Street and Buc-
cleuch Place, where the thermometer must have been influenced by the heat reflect-
ed from the opposite sides of these streets, I consider the mean of his annual tem-
peratures, viz. 4'7°.8, as erring in excess, and haye therefore preferred 46°.25, the
result of Messrs MitLen and Apiz’s observations.

This opinion respecting the temperature of Edinburgh is strongly confirmed
by the following valuable and accurate observations, made and communicated to me
by my friend Mr James Jarpine.

Temperature of the Craw ey Sprine, situated 564 feet above the level of

the sea.
1811, 30th January, = 46°5 Fahrenheit,
21st March, - 46.0
18th April, = 46 .2
19th August, = 46.7
Mean, 46.35

Add for 334 feet above Merchant Court, 1.00.

Mean Temperature at Edinburgh, 47 35

Temrrrature of the Brack Srrine, situated 882 feet above the level of the sea,
1815, 12th January, a 44°.8- Fahrenheit.

1811, 31st January, - 45 .0
1818, 4th February, - 44.6

1811, 18th April, = 44.8
1810, 17th September, - 45 .0
1819, 8th October, - 44.8

1810, 31st December, © - 45 .0

Mean - |. 44186
Add for 652 feet above Merchant Court, 1.95

—=——

46.81 ; a | oa

210 OBSERVATIONS ON THE MEAN TEMPERATURE

mean temperature, according to the observations of Messrs
Minter and Anre, is 46°.23*, agreeing very nearly with the
calculated results. ;

Hitherto we have considered only the temperature of the
Old World, as determined under meridians passing through
the west of Europe ; and previous to actual observation, it was
reasonable to infer, that under other meridians the heat would
follow a similar law of distribution. The testimony of travel-
lers, however, soon corrected this hasty inference ; and as the
condition of more distant climates was better known, the seve-
rity of a Canadian and a Siberian winter became proverbial.
Notwithstanding this evidence, Mayer, and Kirwan, who
adopted his formula, have considered it as universally appli-
cable; and Mr Lesure has maintained, on the authority of a
few insulated facts, that the average temperature of the Old
and New World will be found the same +.

These speculations, however, have been completely over-
turned by the researches of Humsotpt. He has shewn, that
though the temperature of the Equatorial regions is nearly the
same under all meridians, yet in higher latitudes it declines
rapidly in the New World, and under the eastern meridians of

Asia.

Mean Temperature at Edinburgh from

Black Spring, - - 46 .81
Mean Temperature at Edinburgh from
Crawley Spring, - - 47 35

General Mean Temperature of Springs
at Edinburgh, - - 47 08

* These observations were made in Merchant Court, 230 feet above the level
of the sea.

+ Edinburgh Encyclopedia, Art. Amentca, Sect. Climate of America, vol. i.
p- 614.

OF THE GLOBE. 211

Asia. In the three first columns of the following Table, he
has given the differencesof temperature for the Eastern and
Western Hemispheres, under the parallels of 30°, 40°, 50° and
60° of north latitude.

Temp. = Temp. Difference Temp. of Diff. be-
Lat. Old World. New World. betweenOld N. World tween obs.
and N. World. calculated. -& calcul.
30° 70°.52 66.92 3°.60 69°.07 + 215
40 63.14 54.50 8 .64 54.04 — 0.46
50 50 .90 37.94 12.96 88.06 ‘+ 0.12
60 40 .64 23.72 16 92 23 .02 — 0.70

The difference of temperature of the Old and New World is
nearly 4° in the parallel of 30° ; 9° in the parallel of 40°; 13°
in the parallel of 50° ; and 17° in the parallel of 60°.

It would have been desireable to have expressed these dif-
ferences, by adding to the preceding formula a co-efficient de-
pending on the longitude; but the observations are not suffi-
ciently numerous for this purpose, and I have contented my-
self with the following simple expression, which enables us to
calculate’ the temperatures of the New World. ;

T = 81£° Cos.? Lat. x 1.13.

This formula makes the Equatorial and Polar temperature
of the New World the same as those of the Old World, while
in intermediate latitudes the calculated and observed results do
not differ upon an average so much as 1°, as will be seen from
the two last columns of the preceding Table.

The determination of the temperature of North America,
enables us to approximate with more certainty to the degree
of cold which exists at the North Pole; and as this question
must always possess considerable interest in relation to any
attempt that is made to explore these icy regions, I would re-

pd 2, quest

212 OBSERVATIONS ON THE MEAN TEMPERATURE

quest the attention of the Society to the nature of the argu-
ment by which I conceive that we may ascertain the maximum
limit of the Polar temperature. . .

In the Old Continent, the mean heat at 60° of latitude is
40°. In 78° of latitude, Mr Scoressy makes it 17°, and thence
infers that it must be 10° at the Pole. Now, if Mr Scorgssy
had approached the Pole in a meridian passing through the
New World, he would have encountered a cold of 24° in the
latitude of 60° ; and in the parallel of 78° this cold would have
increased to 4°, as deduced from the formula. If we then
subtract from this an anomaly calculated after Mr Scorrssy’s
ingenious process, we’shall find that the Polar temperature
computed in this way is many degrees below the zero of Fah-
renheit’s scale. Or, to state the argument more popularly,’
since the cold at the Pole is 10°, as inferred from observations
made in the mildest meridian, it must fall greatly below this,
and even below zero, if inferred from observations made in the.
coldest meridian. The winds which blow from the continent
of Greenland,—from the northern extremities of America,—
and from the frozen coast of Siberia, must produce at the
North Pole an influence which is scarcely felt in the Spitzber-
gen Seas.

From all these considerations, we are entitled to infer
that the formula, which represents the actual temperatures
with such accuracy from the Equator,- and through all the va-
rieties of climate in the Temperate Zone, even to the parallel
of 78°, where the fixed ice acts with its full influence, is not
likely to fail in its accuracy when extended to its limit ; and,
therefore, that the temperature of the Pole itself is not far

from 0° of Fahrenheit *.
THE

* As this reasoning is founded on the assumption that the Pole is the coldest
roint of the Globe, the results given above will admit of considerable modification,

if

|) OF THE GLOBE. 213

Tue Meteorological observations which have been recently
made in Lancaster Sound by Captain Parry, confirm in a
very remarkable degree the general Formula, and the opinions
respecting Polar temperature, which I have endeavoured to
-establish in the preceding pages*. Instead of “giving too great

a degree of cold to the Arctic latitudes, as every person sup-
posed the Formula to have done, it errs on the opposite side,
and ascribes to the parallel of 742° a temperature of about
6°, whereas Captain Parry found it to be so low as.1°.33.

This intrepid and skilful navigator, whose important disco-
veries in the Arctic Regions do equal honour to the heroism
of the men under his command, and to the liberality of the
British Government, observed the temperature of the regions
which he visited, with peculiar care, and by means of the saree
instruments. ‘The observations were made every two hours;
and as the expedition’ continued’ nearly ‘twelve .months’in the
Parallel of 74 45;,and in the Meridian of 110°, we may consi-
der:‘the mean annual temperature of that point of the gel as)
established by means of above 4300 observations...) 9/0. is

The following abstract) of this valuable Journal':has i
kindly communicated to me by estoy imi with the per-
mission lar the Lords of the. ee 17

Tari 9h Of MOD OT fy S70} rEA _ Ss" eve Of Os 39 ict

x. ne Fi j , x t ) af {tt a) ) : .
if chit supposition. shall be found improbable, as ba pane in the subsequent,
part of this paper.
* This part of the Papers was Sealey rena the Royal Society on. it 4th De-
cember 1820, Fe ASB ONE AR I

4 * .
landia od «

ibs dee Lace

c

214 OBSERVATIONS ON THE MEAN TEMPERATURE

“ ABSTRACT of the Hecra’s Meteorological Journal for Twelve Kalendar
Months, during which Period she was within the Parallels of 74 and 15°
of North Latitude.

Mean Temperature of
Monrus. Air in Shade. REMARKS.

‘< During the time that we were in Win-

1819, September,

October, 6 | ter Harbour, it was always found that the
November, thermometer on board stood from 2° to
December, 5° higher than the one on shore, from the
1820, January, warmth created by the fires, &c. The
February, . minimum temperature for February was
March, — 50° on board, but — 55° on the ice.
April, On the ice, 14th and 15th of February,
May, the thermometer was at — 54° for seven-
June, teen hours.
July,
August, The mean annual temperature may be

fairly considered as 1° or 2° below zero.”
Annual Temperature,

“The intense cold which is thus proved to exist in the lati-
tude of 743°, indicates, when compared with that in 78° in the
Spitzbergen Seas, a very singular state of the Isothermal lines
at the Pole itself. The thermometric curve of 17°, which rises
in the meridian of ‘Spitzbergen to the 78th degree of north
latitude, descends in the meridian of Melville Island to the
65th degree, and unless we suppose that the climate of these
regions is subject to no law, we are forced to conclude that
the Pole of the Globe is not the coldest point of the Arctic
hemisphere, and that there are two points of greatest cold not
many degrees from the Pole, and in meridians nearly at right
angles to that which passes through the west of Europe.

Observations are still wanting to determine the exact posi-
tions of the Isothermal Poles; but they appear to be situated
in about 80° of N. Lat., and in 95° of East and 100° of West

Long.; the Transatlantic one being nearly 5° to the N. of
Graham

OF THE GLOBE. 215
Graham Moore’s Bay in the Polar Sea; and the Asiatic one
to the north of the Bay of Taimura, near the: North-East. Cape.

This view of the distribution of temperature within the Eri-
gid Zone, suggests, or rather renders necessary,:a:- New Law of
the Progression of Climates. The gradation of heat on the
Transatlantic Meridian is so essentially different from that in
the west of Europe, that it is impossible to represent the two
classes of phenomena by one Formula, in which the limiting
temperatures are found at the Equator and the Pole. No at-
tempt, indeed, has been made to include them in the same
law, and still less to refer them to a principle which embraces
all intermediate meridians.

As we are not acquainted with the cause of the anomalous
distribution of heat in high latitudes, observation alone must
guide us in determining the form of the Isothermal lines.
From their general resemblance to the Isochromatic Curves, I
tried to calculate the temperatures by the product of the sines
of the distance of the place from the two Isothermal Poles ;
but this law did not represent the facts, and I found that they
might be more accurately expressed by the Formula

Mean Temp. = 82.8 Sin, D

upon the eae noe that the greatest cold:i is O° of Fahren-
heit, Oi), A

Mean Temp. = 86.3 Sin. D— 3:1
upon the more probable supposition, that the greatest cold
is — 31° of Fahrenheit, 82.8 being the Mean Temperature of
the Equator in the Warmest Meridian, and D the distance of

the place from the nearest Isothermal Pole *.
By

* The distance D from the Isothermal Pole is in the coldest meridian
D=80°—Lat.; and in the warmest meridian Cos. D= Cos. 10° x Sin. Lat.
In

-

216 OBSERVATIONS ON THE MEAN TEMPERATURE

By applying this last Formula to the results obtained by
Humpsotpr, and to the observations of Captain Scorrssy and
Captain Parry, we shall have the following observed and cal-
culated temperatures * :

Mean Temp. of Old World. Mean Temp. of New World.
Lat. Observ. Calc. Difference. Obsery. Calc. Difference.
30° 70°.52 71°.61 + 1°.09 66°.92 62°.61 — 4.31
40 63.14 63.81 40.17 54.50 (51.970 2.58
50 50.90 53 16: + 2.26 37 .94 39 .65 +1.71
60 40 .64 41 .55 +091. 23.72 26 .02 + 2.30
745 Captain Parry, - - 1.33 4.39 +8 .06

78 17.00 19.66 +2 66 Captain Scoresby.

The differences in the fourth and seventh columns are far
from being considerable ; and when we reflect. upon the uncer-
tainty in the position of the Poles, and the range of the annual
temperature at any given place, the coincidence of the obser-
ved and calculated nemalien! is greater than could have been ex-
pected.

In the preceding pis /accomre the places to which the mean
results belong, are supposed to be situated either in the warm
meridian which passes. through the west of Europe, or in the
cold meridian which passes through North America. In com-
paring, however, the theory with observation, we shall proceed
to put it to the severe test of contrasting it with observations
made in intermediate meridians, both in the Old and the New

World ;

Cos. re —— in
Tang. 6= Cos. M. Tang. L, where M is thie’ difference of longitude aie re
place and the Pole, L the co-latitude , fhe isothermal Pole or 10; and Z i co-
latitude of the place.

In all intermediate meridians we have. Cos. D =

* The calculation for the Old World is founded on the supposition, that the
meridian to which the mean-results of Humzoxpt belong is at right angles to the
ccld meridian in 100° West Longitude. .The greater number of places, however,
from which the mean was taken, are nearer the Asiatic. than the American Pole.
Hence we see the reason why the differences are all positive.

i
:

a we

_~,.

OF THE GLOBE. 217

World ; and in this comparison we shall begin with the Asra-
tic Pox, and suppose it to have a temperature of —3°3, and
to be placed in 80° N. Lat. and 95° of East Long: from. Green-
wich.

Distance from the Mean Temperature.

Asiatic Pole. Observed. Calculated. Difference.
Enontekies, 20° 39° 31°.03 * 26.93 —4.10.
Uleo, - 23 16 33 .08 30.59 —2.49
Umeo, - 2506 33.26 83.109 20.15
St Petersburg, 27 11 38 .84 35.92 —2.92
Stockholm, 29 44 42.30 39.30 —3.00
Moscow, - 29 55 43.16 39.54 —3.62
Warsaw, - 36 06 48.56 47.35 .—1.21
Astracan, - 8725 49.08 48 .94 —0.14
Vienna, - 4037 51.76 52.68 +0.92
Pekin, - 40 56 54.86 53.04 —1.82
Nangasaki, 48 57 60.80 61.58 +0.78
Seringapatam, 68 04 77.00¢ | 76.55 —0.45
Columbo, - 7312 79.50 79.12 —0.38

From these differences, which are almost all negative, it ap-
pears that we have assumed too great a degree of cold for the
Asiatic Pole. If we make it 0 of Fahrenheit, we obtain the

following results : '
Mean Temperature.
Observed. Calculated. Difference.

Enontekies, 31.03 29,20 — 1.83
Uleo, - 33 .08 32.71 — 0.37
Umeo, - 33.26 ark, + 1.86
St Petersburg, 38 .84 37.83 — 1.01
Stockholm, 42 .30 41.07 — 1.23
Moscow, - 43 .16 41.30 — 1.86

Warsaw,

* Reduced to the level of the sea by Humzotpr’s rule.
+ The mean temperature in 1814 was 78°.25, and in 1816 75°.75. No-cors
rection is applied for its elevation above the sea.
VOL. IX. P. I. Ee

218 OBSERVATIONS ON THE MEAN TEMPERATURE

Mean Temperature.

Observed. Calculated. Difference.
Warsaw, - 48 .56 48 .79, + 0.23
Astracan, - 49.08 50.31 + 1.23
Vienna, - 51.76 53 .90 + 2.14
Pekin, - 54 .86 54 .25 — 0.61
Nangasaki, 60.80 62.44 + 1.64
Seringapatam, 77.00 76.81 —0.19
Columbo, st. MOWGO OF 79 .26 — 0.24

The differences in this Table (amounting at an average to
I°rs) are far within the limits of the errors of observation ; but
being negative in general, they may be reduced still farther to
an average of 1°, by supposing the Asiatic Pole to have the
temperature of +1° of Fahrenheit, which is 43° warmer than
the Transatlantic Pole. The Formula in this case becomes

T = 81.8 Sin. D+1’,
from which we obtain the following results :

Mean. Temperature

Observed... Calculated. Difference.
Enontekies, 31°03. 29.85 =. Jue
Uleo, . 33.08 33.31 + 0.23
Umeo, - 33 .26 35.70 + 2.44
St Petersburg, 38 .84 38.37 — 0.47
Stockholm, 42 .30 41.57 — 0.73
Moscow, - 43 .16 41.80 — 1.36
Warsaw, - 48 .56 49.20 +- 0.64
Astracan, - 49.08 50.70 + 1.62
Vienna, = - 51.76 54:25 + 2.49
Pekin, - 54 86 54.59 — 6.27
Nangasaki, 60 .80 62.69 + 1.89
Seringapatam, 77.00 76.92 — 0.08
Columbo, - 79 .50 79.33 ear

In

OF THE GLOBE. 219

In comparing the theory with observations made round the
Transatlantic Pole, the results: are equally satisfactory. The
third column of the following table is calculated from the for-
mula T= 86°,3 Sin. D—3%3, and the Pole is supposed to be
situated in 80° N. Lat, sia 100° Wise stint » and to have a
isk: clopeee Of = Sh. |

Distancetremethe Mean Temperature. “)

American Pole. — Observed. Calculated. Difference.
Melville Island, 6815 1°.38 4°.39 + 3°.06
Upernavick, 12 15 16.34 14.81 -— 1.58
Omenak, ~ 18°58" 16.60 17.33 +0.42
Godhavn, 17 08 22 04 21.92 —0.12
Godthaab, 2019 26.07 26.46 40.39
Fort Churchhill, 20 58 25 .34 27 .38 +2.04
Julianeshadb;:) 94-850) 180488 B27 eV .84
Eyafiord, 24 08 32.16 81.78 — 0.38
Nain, - 25 16 30.03 + 33 .84 +3.31
Okkak, - 24 47 31 .00 t 32 .68 + 1.68
Quebec, 34 44 41.90 45.67 + 3.77
Cambridge, 39 04 50.86 50 89 + 0.53
New York, 39 58 53 .78 51.84 — 1,94

Philadelphia, 41 08 53.42 53.27 0.15
Williamsburg, 43 40 58.10 56.09 2.01

Orotava, 60 00 70.11 71,24 +1.18
W.L.100, 81,5 0 .0

Equaron { E.long.95- 80 00 81.50 $1.56 + 0,06
Ee 2 In

* If we suppose that the observations in West Greenland, and those about Hud-
son’s Bay and Labrador, are best fitted’ to give the position of the Pole, it is ob-
vious, that it should be removed a little from the former, and brought nearer the
latter, so as to be placed a degree or so farther South. 'This change would also
produce a greater coincidence with Captain Parry’s observations.

+ For 1779—80. See Phil. Trans. ¢ For 1779—80. See Phil. Trans.

220 OBSERVATIONS ON THE MEAN TEMPERATURE

In the reasoning from which Humzorpr estimates the mean
temperature of the Equator, he appears to me to have taken
for granted a very material fact. Having found a coincidence
between the mean temperature of equinoctial America and
equinoctial Asia, he concludes that the mean temperature of
the Equator is 81°.5, and is uniform in every point of! that
great circle; but as these are the very regions under the line
where the temperature should be the same, in consequence of
being similarly situated with regard to Canada and Siberia, no
conclusion can be drawn until a similar temperature has been
found on the African coasts of Benin and Loango. The heat
under the Equator being thus supposed to be uniform, Hum-
potpt felt himself entitled to conclude, that the colds of Ca-
nada and Siberia did not extend their influence to the equato-
rial plains *, and that between the tropics, the isothermal lines
are parallel to the equinoctial.

The theory which I have explained above, requires a diffe-
rent distribution of heat at the Equator. The maximum mean
temperature of that circle should be 82°.8 in Africa, in or-
der to give 81°.5 as the equinoctial temperature in America and
Asia; and the difference of these values, or 1°.3, must be re-
garded as a measure of the influence which the colds of Canada
and Siberia extend to the equatorial plains. Nor is this a mere
theoretical result. I consider it as fairly deducible from facts
furnished by Humsoxpr himself; and this distinguished travel-
ler seems to have drawn from these facts the same conclusion,
before he had deduced the uniformity of the equatorial tem-

perature

* Edinburgh Philosophical Journal, vol. iii. p. 263.

OF THE GLOBE. 22)

perature from a comparison of Asiatic and American observa-
tions.

In his Political Essay on New Spain, he makes the follow-

ing remarks ; “ On the eastern coast of New Spain, the great

‘ heats are occasionally interrupted by strata of cold air,

brought by the winds from Hudson’s Bay towards the pa-
rallels of the Havannah and Vera Cruz. These impetuous
winds blow from October to March; they are announced by
the extraordinary manner in which they disturb the regular
recurrence of the small atmospherical tides, or horary varia-
tions of the barometer, and they frequently cool the air to
such a degree, that at Havannah, the centigrade thermome-
ter descends to 32° of Fahr., and at Vera Cruz to 60°.8 Fahr.
—a prodigious fall for countries in the torrid zone.”—Vol. I.
65. Eng. edit. “ The great breadth of the New Continent,
—the proximity of Canada,—the winds which blow from the
north, §c. give the equinoctial regions of Mexico and the
island of Cuba a particular character. One would say, that
in these regions the temperate zone,—the zone of variable
climates,—increases towards the south, and passes the tropic of
Cancer,” &c.—Vol. II. p.410. “ On the east coast of Mexi-
co,” he elsewhere remarks, “ the north winds cool the air,
so that the thermometer falls to 62°.6 Fahr ; and at the end
of the month of February, I have seen it remain for whole
days under 69°.8; while, during the same period, the air be-
ing calm, at Acapulco, it is between 82°.4 and 86°. The
latitude of Acapulco (16° 50’) is 3° farther south than that
of Vera Cruz; and the high Cordilleras of Mexico shelter it

“ from the currents of cold air which rush in from Canada upon

173

Hudson’s Bay produce a very striking effect upon the climate

the coast of Tabasco,” (Lat. 18°)—Vol. II. p. 148. *
From these quotations, it appears, that the cold winds from

even

* See also, vol. I. p. 75.

222 OBSERVATIONS ON THE MEAN TEMPERATURE

even of the tropical regions. Rising in the parallel of 60°,
and sweeping over the whole continent of North America,
_ through an extent of 2600 miles, they retain their gelid in-
fluence even in the latitude of 18°. Can we suppose, then, that
such winds as these cease all at once to impart their cooling
energies to more southern zones. Acting with such power in
the parallel of 18°, will they not refresh the opposite shores of
the Pacific Ocean, and temper even the burning heats of the
Equinoctial Line? Whatever law of progression we may
adopt to represent the decreasing influence of these northern
currents, in their passage towards the Line, there is none
which allows them the influence described by Humsotpr on
the coast of Tabasco, that will not extend that influence to the
Lquator itself.

Although the preceding views, respecting the distribution
of heat within the Polar Circle, make the temperature much
lower than had previously been supposed, yet when taken in
conjunction with the results of the expedition under Captain
Panry, they rather encourage the hopes which have been so
reasonably entertained, of reaching the Pole itself.

Upon the supposition that there are ¢wo Isothermal Centres
in 80> of latitude, and that their temperature is — 3} of Fabren-
heit, the mean temperature of the Pole of the Globe will be about
11°, incomparably warmer than the regions in which Captain
Parry spent the winter, If an expedition, therefore, were to.
set out for Spitzbergen, and remain there for one or more sea-
sons, till an opening should be found through the icy barrier
which stretches from that island to the Greenland coast, there
is every reason to believe that it would ultimately succeed.

If the Pole is placed in an open sea, the difficulty of reach-
ing it entirely ceases; and if it forms part of a frozen conti-
nent, those intrepid individuals who sustained the rigorous

cold

OF THE GLOBE. 293

cold of Lancaster Sound, could experience no hardship under
a comparatively milder climate.

Hitherto we have supposed the two Isothermal Poles to have
the same temperature, and to be situated on nearly opposite
Meridians; but this supposition is not rendered necessary by
any of the phenomena, and we may obtain a better expression
of the temperatures, by placing the Poles at different distan-
ces from the Equator, and ascribing to them different intensi-
ties. ‘The existence of a cold and a warm meridian, is a proof
that there are causes which powerfully influence the annual
temperature, independent of the position of the Earth’s axis
with respect to the Sun; so that the effects which they pro-
duce can have no symmetrical relation to the Pole either in
position or intensity.

The two Northern Poles of the terrestrial magnet, for ex-
ample, are situated, the one 4° and the other 20° from the Pole,
and they have neither equal intensities, nor opposite positions,
Imperfect as: the: analogy is between the Isothermal and the
Magnetic centres, it is yet too important to be passed over
without notice. Their ‘local coincidence is sufficiently remark-
able, and it would be to overstep the limits of philosophical
caution, to maintain that they have no other connection but
that of accidental locality... The revolution of the two Magne-
tic foci round the Pole, the one in 1740. years, and the other
in 860, has been. recently deduced by Hanstzxn from nume-
rous observations, and if we had as) many measures of the
mean temperature, as we have of the variation of the needle,
we might determine whether. the Isothermal Poles were fixed
or moveable. =
_ The idea of such a ete suggests a an eseulandlidw of some
of the most remarkable revolutions on the surface of the
Globe.. , There is no fact in the Natural History of the Earth
better ‘ascertained, than that the climate of the west of Europe

was

Q94 OBSERVATIONS ON THE MEAN TEMPERATURE

was much colder in ancient than in modern times. When we
learn that the Tyber was often frozen ;—that snow lay at
Rome for forty days;—that grapes would not ripen to the
north of the Cevennes ;—that the Euxine Sea was frozen over
every winter in the time of Ovip ;—and that the ice of the
Rhine and the Rhone sustained loaded waggons ;—we cannot
ascribe the amelioration of such climates to the influence of
agricultural operations.

The cold Meridian which now passes through Canada and
Siberia, may then have passed through Italy ; and if we trans-
fer the present mean temperatures of these cold regions, to the
corresponding parallels in Europe, we shall obtain a climate
agreeing in a singular manner with that which is described in
ancient authors.

It is not, however, in the altered condition of our atmo-
sphere merely, that we are to seek for proofs of a periodical
rotation of climate. The impressions of the plants of warm
countries, and the fossil remains of land and sea animals,
which could exist only under the genial influence of the Tem-
perate Zone, are found dispersed over the frozen regions of
Eastern Asia; and there is scarcely a spot on the solid coyer-
ing of the Globe, that does not contain indications of a revo-
lution in its animal and vegetable productions.

This interchange of the productions of opposite climates,
has been ascribed to some sudden alteration in the obliquity
of the Ecliptic, and even to a violent displacement of the
Earth’s axis; but Astronomy rejects such explanations, as ir-
reconcileable with the present condition of the system, and as
incompatible with the stability of the laws by which it is go-
verned.

Havine

OF THE GLOBE. 225

Havine thus endeavoured to establish a new law of the dis-
tribution of heat over the surface of the globe, it might be no
uninteresting inquiry to investigate the causes which have mo-
dified, in so remarkable a manner, the regular influence of the
solar rays. The subject, however, is too comprehensive, and
too hypothetical, to be discussed at present. How far the ge-
neral form and position of the continents and seas of the north-
ern hemisphere may disturb the natural parallelism of the iso-
thermal lines to the Equator.—To what extent the current
through Behring’s Strait, transporting the waters of warmer
climates across the Polar seas, may produce a warm meridian
‘in the direction of its motion, and throw the coldest points of
the globe to a distance from the Pole-—Whether or not the
magnetic, or galvanic, or chemical poles of the globe, (as the
important discoveries of M. Orrstep entitle us to call them),
may have their operations accompanied with the production of
cold, one of the most ordinary effects of chemical action.—Or
whether the great metallic mass which crosses the globe, and
on which its magnetic phenomena have been supposed to de-
pend, may not occasion a greater radiation of heat from those
points where it developes its magnetic influence ?—are a few
points, which we may attempt to discuss, when the progress
of science has accumulated a greater number of facts, and made
us better acquainted with the superficial condition, as well as
the internal organization, of the globe.

VOL. 1X. P, I. Ff XIV.
)

.

pene
%

ae oghapa .f
“seals

XIV. Method of determining the Latitude, by a Sewtant or
Circle, with simplicity and accuracy, from Circum-meri-
dian Observations, taken near Noon. By Major-Gene-
ral Sir Tuomas Brispang, C. B. F. R. S. E. and Cor-
responding Member of the Institute of France.

(Read November 20. 1820.)

As it very frequently happens that an observation may not
be obtained for the latitude, at the precise instant of noon, it
. becomes a most desirable object to supply that loss by every
possible means. The method which I am about to detail,
I have long practised, and from the experience of many hun-
dred trials, I can recommend it, as combining much simplici-
ty with the greatest accuracy ; since one day’s. observations
may be equal to those derived from the chances of three weeks
of the ordinary course of weather in our climate. This me-
thod consists in merely reducing to noon these observations,
the same as if made when the sun’s centre was on the meri-
dian, by the means of a very simple calculation, which 1
shall detail, and illustrate with the observations for two days,
in order to shew the accuracy of the results thus obtained.
Having previously ascertained the time of noon, either by
equal altitudes, or from simple ones, in the manner I had the

Ff 2 honour

228 METHOD OF DETERMINING THE LATITUDE BY

honour to detail in a former communication to the Society,
“ On the Mode of determining Time with the Sextant,” I begin
nearly 10’ from noon to ee the sun’s altitude, from an ar-
tificial horizon of oil, or quicksilver, and continue making as
many observations as I can accomplish until the sun has near-
ly the same altitude as when I began, which will be the case
about as long past noon, during which an expert observer will
easily take 20 altitudes, which, in most cases, will be sufficient
to enable him to retain all those that appear to be consistent,
and to reject those that differ much from the mean. The er-
ror of the instrument is to be carefully determined * ; and the
barometer and thermometer must be noted, and their results
deduced, agreeably to the two examples that accompany this
memoir.

I have always found it the readiest mode to correct the
noon declination, as given at Greenwich, first, for the differ-
ence of meridians, and next for the time of the observations,
which is most readily done by calculating what the change in
one minute of time will produce, and then multiply that by
the number of minutes required for the given observation f.

Having

* At sea, or where it is not required to proceed with the greatest accuracy,
the mean refraction may be used, without having recourse to the correction for
aimospherical pressure and temperature.

+ If the place of the observer is west of the first meridian, it becomes neces-
sary to add the proportional part to the noon declination, for the difference of me-
ridians, from the Vernal Equinox until the Summer Solstice, and from the Au-
tumnal Equinox to the Winter Solstice ; but for the rest of the year it must be
subtracted. If the observer is situated east of the first meridian, it must be sub-
tracted during the spring and autumn, but added during summer and winter.
Had the sun no motion in declination during the time that the observations conti-
nue, it would be unnecessary to apply any correction, as in the case of observing by
the stars ; but although the quantity is very small Sieg so short a period of time,

still

ro

CIRCUM-MERIDIAN OBSERVATIONS TAKEN NEAR NOON.’ 229

Having thus determined or corrected the declination for
each observation, there remains nothing to be done but to ap-
ply it according to its sign, either to the zenith distance or al-
titude, according as it is north or south, in order to obtain the
latitude corresponding to each observation.

That most justly celebrated astronomer M. Drtamsrz, to
whom all practical astronomers are most deeply indebted, fa-
voured me with the following formula, for correcting or re-
ducing to noon these observations,

___ 2Sine?1 P_ (Cos H Cos D 2Sine* P Cos H Cos D

3 °
Al 7 7 \Sine + eh T Sne ke. \Sine (H+ D)) seen eae

This correction appears to be tedious to compute, but, by t he

2 Sine? 3 P d 2 Sine #

help of the Tables of —[47—- an ae the calculation

Sine 1”

will be much abridged.
The second factor of the first term requires to be computed
only to five places of decimals, and the looking out of three
‘logarithms. ‘The second factor of the second term is formed
. Co-si i 2
from the preceding one, Sy py _ being squared, and
then multiply it by the Co-tangent (H + D).
The second part of the above I have omitted, as in observa-
tions taken nearly 15° from noon, I have never found the cor-
rection resulting from it amount to half a second; but I have

been

still it is requisite to pay attention to it. For this purpose the proportional part
of the declination, corresponding to the horary angle of the observation, is to be
added to the declination at noon, in order to have it for the instant of observation,
when the observation is made before noon, and the declination is diminishing
If the observation is made in the afternoon, the proportional part must be sub.
tracted.

230 METHOD OF DETERMINING THE LATITUDE BY

been induced to give it, in order that those who are desirous
may avail themselves, to the full extent, of the correction,
which for the Pole Star may become requisite, when the ob-
servations are extended from 15 to 20 or longer after its pas-
sage over the meridian. The product of these quantities give
a logarithm termed f, which, added to the logarithm of
ae taken from the Table, corresponding to the horary
angle, gives the logarithm of the correction to be added to the
altitude, or subtracted from the zenith distance ; from whence
their apparent ones are to be determined.

The accompanying Table, valuable for many purposes of ..

c Lea ® } y
astronomy, Viz. Se is extended to 11’ from noon, which

is generally sufficient ; but those who are desirous of ob-
serving further from noon, may continue it agreeably to the
above formule. This Table, with Lazanpe’s small volume
of Logarithms *, are all that is required for the determina-
tion of the latitude by this method. The above correction,
or Log. f, is equally applicable to the repeating circle as to
the sextant, with this difference only, that the number of re-
petitions must be multiplied by that number, or in other
words, the logarithm of the number must be added, in or-
der to obtain the reduction to noon for their sum. I have
been induced to compute for my own observatory logarithm f

for

Or

* No astronomer should be without this little work, or CaLzet’s tables, both
of which, from their value, and universal use in calculations, have been stereoty-
ped in France, and abridge, in a most wonderful degree, the proportions required
in all astronomical computations. As the one term is invariaby constant, viz. 24
hours, the change that takes place in declination, the sun’s longitude, or AR, serves
for all the calculations of one day ; so that in fact there are but two logarithms
to look out, in the most complicated proportion.

CIRCUM-MERIDIAN OBSERVATIONS TAKEN NEAR NOON. 231

for every 10’ of the sun’s declination, both north and south
of the equator, with a column of differences, so that Ican de-
termine, almost by inspection, the numbers for the interme-
diate minutes; and this I would recommend to any one who
means to prosecute these observations for a considerable time,
or in a fixed observatory, as this Table is equally applicable
_ for the corrections of observations made on the fixed stars or
planets, whose declinations do not exceed the limits of the
Table ; otherwise it will be necessary to extend it to a greater
range in declination. By pursuing this simple process, I am |
of opinion, that the latitude of any place may be determined
to within a few seconds from a single day’s observations ; and I
have further discovered, that those taken at a distance from the
meridian afford just as satisfactory results as if they were taken
at the instant of noon ; and this I have confirmed by a variety
of trials.

TABLE

TABLE or 2Sine?3P

Sine 1”

For Reductions to the Meridian Observations made with the Circle or Sextant near
Noon, for determining the Latitude, and is constructed agreeably to the above
Formula. Argument the Horary Angle in Time.

0’ V Q 3’ At bY 6 ] ig Ss Yy
0 | 0.00 | 1.96] 7.85 | 17.67] 31.41 | 49.09 | 70.68 96.20 | 125.65 | 159.02
0.00 | 2.03) 7.99 |17.87| 31.68 | 49.41 | 71.07 96.66 | 126.17 | 159.61
0.00 | 2.10] 8.12 | 18.07| 31.94 | 49.74 | 71.47 97,12 126.70 | 160.20
0.00 | 2.16] 8.25 | 18.27] 32.21 | 50.07 | 71.86 97.58 | 127.23 | 160.79
0.01 | 2.23] 9.39 |18.47| 32.47 | 50.40 | 72.26 | 98.04 | 127.75 | 161.39
0.01 | 2.30] 8.52 | 18.67] 32.74 | 50.74 | 72.66 98.51 | 128.28 | 161.98 |
0,02 | 2.38] 8.66 | 18.87] 33.01 | 51.07 | 73.06 98.97 | 128.81 162.58
9.03 | 2.45} 8.80 | 19.07] 33.27 | 51.40 | 73.46 99.44 | 129.34 | 163.17
0.03 | 2.52| 8.94 | 19.28] 33.54 | 51.74] 73.86 99.90 | 129.87 | 163.77
0.04 | 2.60] 9.68 |19.48| 33.82 | 52.07 | 74.26 100.3% 130.41 164.37

0.05 | 2.67| 9.22 |19.69| 34.09 | 52.42 | 74.66 100.84 130.94 164,97
0.07 | 2.75| 9.36 | 19.90 | 34.36 | 52.75 | 75.07 101.31 131.48 165.57
0.08 | 2.83] 9,50 | 20.11] 34.64 | 53.09 | 75.47 101.78 132.01 166.17
0.09 | 2.91] 9.65 | 20.32] 34.91 | 53.43 | 75.88 102.25 132.55 166.77
0.11 | 2.99] 9.79 | 20.53] 35.19 | 53.77 | 76.29 102.72 133.09 167.37

0.12 | 3.07] 9.94 | 20.74| 35.46 | 54.12 | 76.70 103.20 133.63 167.98
0.14 | 3.15] 10.09 |. 20.95] 35.74 | 54.46 | 77.10 103.67 134.17 168.58
0.16 | 3.23| 10,24 | 21.17] 36.02 | 54.81 | 77.51 104.15 134.71 169.19
0.18 | 3.32] 10.39 | 21.38] 36.30 | 55.15 | 77.92 104.63 135.25 169.80
0.20 | 3.40] 10.54 | 21-60] 36.59 | 55.50 | 78.34 105.10 135.79 170.41

0.22 | 3.49 | 10.69 | 21.82] 36.87 | 55.85 | 78.75 105.58 136.34 171.02
0.24 | 3.58] 10.84 | 22.03] 37.15 | 56.20 | 79.17 106.06 136.88 171.63
0.26 | 3.67] 11.00 | 22.25] 37.44 | 56.55 | 79.58 106.55 137.43 172.24
0.29 | 3.76 | 11.15 | 22.48] 37.72 | 56.90 | 80.00 107.03 137 98 172.86
0.31 | 3,85] 11.31 | 22.70} 38.01 | 57.25 | 80.42 107.51 138.53 173.47

0.34 | 3.94] 11.47 | 22.92] 38.30 | 57.61 | 80.84 108.00 139.08 174.09 —
0.37 | 4.03 | 11.63 | 23.14 | 38.59 | 57.96 | 81.26 108.48 139.63 174.70
0.40 | 4.13 | 11279 | 23.37] 38.88 | 58.32 | 81.68 100,97 140.18 175.32
0.43 | 4.22 | 11,95 | 23.60] 39.17 | 58.63 | 82.10 109.46 140.74 175.94
0.46 | 4.32] 12.11 | 23.82] 39.47 | 59.03 | 82.53 109.95 141.29 176.56

0.49 | 4.42 | 12.97 | 24.05| 39.76 | 59.39 | 8295 | 11044 | 14185 | 177.18
6.02 | 4.52 | 12.44 | 2428] 40.05 | 59.76 | 93.38 | 110.93 | 142.40 | 177.80
0.56 | 4.62] 12.60 | 24.51 40.35 | 60.11 | 83.81 | 111.42 | 142.96 | 178.42
0.59 | 4.72 | 12.77 | 24.74! 40.65 | 60.48] 984.93 | 111.91 | 143.52 | 179.05
0.63 | 4.82| 12.94 | 24.98] 40.95 | 60.84] $466 | 112-41 | 144.08 | 179.68

0.67 | 4.92] 13.10 | 24.21] 41.25 | 61.21 85.09 112.90 144.64 180.30 9
0.71 | 5.03 | 13.27 | 25.45] 41.55 | 61.57 | 85.52 113.40 145.20 180,93
0.75 | 5.13] 13.44 | 25.68] 41.85 | 61.94 | £5.96 113.90 145.77 181.56
0.79 | 5.24| 13.62 | 25.92] 42.15 | 62.31 | 86.39 114,40 146.33 182.19
0.83 | 5.35| 13.79 | 26.16] 42.45 | 62.68 | 86.82 114.90 146.90 182.82

0.87 | 5.45] 13.96 | 26.40] 42,76 | 63.05 | 87.26 115.40 147.46 183,45
0.92 | 5.56| 14.14 | 26.64] 43.06 | 63.42 | 87,70 115,90 148.03 184.09
0.96 | 5.67| 14.31 | 26.88] 43.37 | 63.79 | 88.13 116.40 148.60 184,72
1.01 | 5.79 | 14.49 | 27.12] 43.68 | 64.16 | 88.57 116.91 149.17 185.35
1.06 | 5.90 | 14.67 | 27.37] 43.99 | 64.54 | 89.01 117.41 149.74 185.99
1.10 | 6.01 | 14.85 | 27.61] 4430 | 64,91 | 89.46 117.92 150.31 186.63
1.15 | 6.13] 15.03 | 27.86] 44.61 | 65.29 | 89.90 118.43 150.88 187.27
1.20 | 6.24] 15 21 } 28.10] 44.92 | 65,67 | 90.34 118.94 151.46 187.91
1.26 | 6.36 | 15.39 | 28.35| 45.24 | 66.05 | 90.79 119.45 152.03 188.55
1.31 | 6.48 | 15.58 | 28.60| 45.55 | 66.43 | 91.23 119.96 152.61 189.19
1.36 | 6.60 | 15.76 | 28.85| 45.87 | 66.81 | 91.68 120.47 153,19 189.83
1.42 | 6.72 | 15.95 | 29.10] 46.18 | 67.19 | 92.13 120.98 153.77 190.47
1.48 | 6.84] 16.14 | 29.36 | 46.50 | 67.58 | 92.57 121.50 154.35 191.12
1.53 | 6.96 | 16.32 | 29.61 | 46.82 | 67.96 | 93.02 122.01 154.93 191.76
1.59 | 7.09 | 16.51 | 29.86 | 47.14 | 68.35 | 93.47 122.53 155.51 192.41
1.65 | 7.21 | 16.70 | 30.12] 47.46 | 68.73 | 93.93 123.05 156.09 193.06
1.71 | 7.34 | 1n.89 | 30.38 | 47.79 | 69.12 | 94.38 123.57 156.68 193.71
1.77 | 7.47 | 17.08 | 30.64] 48.11 | 69.51 | 94.83 124.09 157.26 194.36
1.83 | 7.59 | 17.28 | 30.89] 48.43 | 69.90 | 95.29 124.61 157.85 195.02
1.90 | 7.72 | 17.48 | 31.15] 48.76 | 70.29 | 95.75 125.13 158.43 195.67

Circum-meridian Observations made at Makerstown, 9th Februar ‘y 1820, in order to determine the Latitude,

Glass Roofs.

Noon by Chronometer. Time from

we? Noon.

0713

0 58 30 8.43

0 4 7.09

152 5.21

245 4.28

3 36 3.37

447 2.26

5 57 1.16

6 40 0.33

749 0.36

8 37 1.24

9 37 2.24

10 33 3.20

11 47 4.34

12 45 5.32

13 45 6,32

14 40 T2T

15 40 8.27
Numbers corresponding to horary angles, - 149.17
Logarithms, = z 3 2.17368
Constant factor, or Log. - - .76309
Constant factor + Log. of numbers, - 1.93677
Corrections, - - + 86.4
©’s declination corrected for different ee D=14 5451.5
Corrections for horary angles, + 7.0
D correction - - 145 54 58,5
Altitudes corrected for error of i instrument, - of 19 15 35.0
Semi-diameter + Parallax — Reis - + 13891
Refraction to noon, 2 + 1 26.4
Co-latitudes, or Lea of equator, - 34 25 39.0
Latitudes, - - 55 34 21.0

2 Sine ?}P
Sine 1”

149.17
100.37
56.20
39.17
25.68
11.63
3.15
0.59
0.71
3.85
11.81
21.82
40.95
60.11
83.81
108.97
140.18

100.87
2.00160
9.76309

1.76469
58.2

14 5451.5
+ 5.7

14 54 67.2
16 10.0
13 39.1

58,2

25 44.5
3415.5

Observed
Angles.

38 31 40
82 50
$3 30
34 10
34 80
385 00
85 10
35 05
35 00
34 50
34 40
34 50
34 20
34 00
33 40
33 20
32 30

56.20
1.74974
9.76309

1.51283
32.6

14 54 51.5
+ 4.3

14 54 53.8
16 30.0
13 39.1

32.6

25 37.5
34 22.5

Altitudes corrected
for errar of instru-
ment — 30’

19

89.17
1.59295
9.76309

1.35604
22.7

15 35
16 10
16 30
16 50
17 00
17:15
17 20
17 17
17 15
17 10
17 05
17 00
16 55
16 45
16 35
16 25
16 00

or

Latitudes,

55 34 21.0
34 15.5
34 22.5
34 13.1
34 11.6
34 05.8
34 06.6
34 11.2
34 14.5
84 18.3
34 20.3
34 19.5
34 14.3
34 14.0
34 11.0
34 O71
34 15.0

Mean, 55 34 14.2

25.68
1.40960
9.76309

1.17269
14.9

14 54 51.5 14 54 51.5
+ 3.6 + 29

14 54 55.1 14 54 54.4

16 50.0 17 00.0
13 39.1 13 39.1

22.7 14.9
25 46.9 25 48.4
5413.1 34116

11.63
1.06558
.76309

0.82867
6.7

14 54 51.5
+ 19
14 54 53.4
17 15.0
13 89.1
6.7

25 54.2
34 05.8

Taste I.

Co-sine H Co-sine D
L = Se ee
6S Sine (H + D)
Formula for Log f
H 55 34 32 Co-sine 9.75229
D 14 54 51 Co-sine 9.98512

*H+D = 70 29 23 Ar, Co-sine 0.02568

Mean of 17 Lativades = 55 34

3.15 0.59
0.49831 9.77085
9.76309 9.76309
0.26140 9.53394

18 0.8

YU 54 51.5 14 54 51.5
PY 1.0 Sa 0.4
14 54 52.5 14 54 51.9
17 20 1717.5
13 39.1 13 39.1
18 3

25 53.4 25 48,8
34 06.6 3411.2

0.71
9.85126
9.76309

9.61435
0.4

14 54 51.5
_ 0.5
14 5451.0
17 15.0

13 39.1

4

25 45.5
3414.5

Note. * H becomes — D when the Sun or Star is North of the Equator

9.76309

3.85
0.58546
9.76309

11.31
1.6346
9.76309
0.81655

6.6

14 5451.5
— 19

14 5449.6
15
1839.1

6.6
2539.7
3420.3

© declination at noon Ephemeris, =~
10° 4” west of Greenwich,

(Vol. IX. Part I.—p. 233.)

et, th
1455 1
9.5

——

Declination corrected for different meridians, 14 54 51.5

Barometer,

For the refraction.
29.40 = 0.7469 = 9.9925

‘Thermometer, -
Zenith distance, =

21,82
1.33885
9.76309

1.10194
12.6

14 5451.5
2.7

14 54 48,8
17 00
13 39.1

12.6

25 40.5
3419.5

40.95
1.61225
9.76309
1.37534

23.7

14 5451.5
_ 3.6

14 54 47.9
16 55.0

13 39.1
23.7

25 45.7
34143

47 8,33 = 0.0027
70 2.2009
42.7 70
2.2129
Refraction, — 1633
Parallax, + 8.4
554.9
— 2349
Semi-diameter, + 16 140
Correction, + 13 39.1
60.11 83.81
1.77895 1.92330
9.76309 9.76309
1.54204 1.68639
34.8 48.6
14 54 51-5 14 54 51.5
= 44 _ 52
14 54 47.1 14 54 46.3
16 45.0 16 35.0
13 39.1 13 39.1
34.8 48.6
25 46.0 25 49.0
3414.0 3411.0

108.97
2.03731
9.76309
1,80040

63.2

14 6451.5
— 59

and with a view of ascertaining the Accumey that may be obtained by that Mode of Observing —Lonerruve in Time West of Greenwich, nearly 10.4”, Quicksilver Horizon, covered by one of Troughton’s

140.18
2.14669
9.76309

1.90978
81.2

14 54 51,5
68

14 54 44.7
16 00.0
13 39.1

121.2

25 45.0
3415.0

(Vol, 1X. Part I—p. 234.) Tasre Il.

Circum-meridian Observations made at Makerstown, 10th February 1820, in order to determmn® the Latitude, and with a View of ascertaining the Accuracy that may be obtained by that Mode of observing. —Lonerrune in Time west of Greenwich nearly 10’ 4”. Quicksilver Horizon, covered by one of Trou ghi ton's

Glass Roofs.
Noon by Chronometer. Time from 2 Sine? 2 P Observed Altitudes corrected Latitudes — Co-sine H Co-sine D ©’s declination at n E 4 os =
4 a) Noon. Sine 1” Anges. for error of instru- deduced. Log. f= Sine (H + D) 10! 4’ west Fay eee) 1a Pena, = ae ee
07 5 ment — 45” > ee Sh
F, “ One, oe 1 Deelinatio: i idi
Rie 5.58 6796 8g. 18.00 17 38 a5 55 84 180 Popniile fo Log a eens OD
2 37 4,28 39.17 13.20 35 52.5 34 20.8 H = 55 34 32 Cosine 9.75929
3 47 3.18 21.88 13 20 36 17.5 84 07.2 D=14385 79 —Co-sine 9.98576
4 42 2.93 W115 18 25 36 20.0 84113 aes
5 36 1.29 4,32 132 36 21.0 34 15.0 * 11+ D = 70 10 11 Ar. Co-sine 0.02655
6 48 0.17 0.16 13 30 6 22.5 a 169 oe
8 03 0.58 1.83 13 30 92.5 34 16.9 Log. f = 9.76460 :
9 06 201 7.99 15 25 36 20.0 34 16.6 oi Barometer, 5 Pata ee 9938
9 59 . 254 16.51 13 05 36 10.0 G4 29.5 Thermometer, - 46.3—= 80 = 0.0033
10 49 3.44 27.37 12.50 86 2.5 84 24.3 Zenith distance, - 0 ~~ 9.9909
ll 42 4.37 41.85 1245 36 0.0 34 19.2 i ; 36 94
12 24 5.19 55.49 12.30 35 52.5 34 19.2 :
13 06 6.01 71.07 1200 85 37.5 84 25.8 2.2074
14 05 7.00 96.20 1145 35 30.0 34 19.5 Retraction ae ee GLs
V4 54 7.49 119.96 1110 35 12.5 34 23.8 Tabs, mG
16 16 911 165.57 10 20 84 47.5 84 23.3 ; :
17 18 10.13 204.92 9.50 34 32.5 34 16.3 152.8
Se — 232.8
Mean — 55 34 18.6 ©’ssemi-diameter, + 16 13.8
Semi-diameter + Parallax — Refraction = 13 41.0
Numbers corresponding to horary angles, 67.96 89.17 21.38 W15 4.82 016 5 1.83 7.99 16.51 27.37 41.85 55.4! Bravict
: 7 9. ‘ 3 : . f A t l j i 71.07 6.20 119.96 i : )
qoeaihms, - = : 1.83295 1.59295 1.33001 1.04727 0.63548 9.20412 0.26245) 0.90255 1.21775 1.43727 1,62170 LTA 1.85169 192818 Prin 2s1806 oeies
stant factor, or Log. f, - - 9.76460 9.76460 9.7646) 9.76460 9.76460 9.76460 9.76460 9.76460 .76460 9.76460 76460 76460 9.76460 9.76460 9.76460 9.76460 9.76460.
Constant factor 4+ Log. of numbers, - 1.59685 1.35755 1.0946) 0.81187 0.40008 6872 66 235 2 5 618
Garou iB , 59685 (35755, 0946) . . 8.96872 0.02705 0.66715 0.98235 1.20187 1.38630 1.50881 1.61629 1.74778 1.84364 1.98358 2.07618
, - = af ET HS 22:8 12: 6.5 25 0.1 ll 47 9.6 15.9 24.3 32.3 41.3 55.9 69.8 96.3 119.2
:. My - o «y 4
Skeet corrected for diferent meridians, D = 14 $5993 143539.3° 143533 1435393 1435393 1495993 1435393 1495993 1485393 1485393 1435893 1495398 1435398 1435393 1435393 1495893 14 95 393
orrections for horary angles, z a ag ay ee 816. + 96 + 19° 4 ey Bs O02 08 ee Ole 2A 180, SSG Be Eger by oo Ga) tn Ta) ee
D corrected, : z 41635440 1495429 ldap hp J495 42 1495405 1495995 1495985 1135977 1485809 1485863 1495 955 14 55 8 14 35 33.6 : 10!
: : ! 2 5 419 4 } 5 39 38, d \ ; f 50 1435 $44 14-35 93.6 1 “ 31. 35,310),
Alliides correeted for error of instrument, + 19 35 875 85, 52.5 36 115 36 20.0 36 21.0 36 22.5 36 22.5 36 20.0 86 10.0 36 25 36 0.0 35 52.5 85 37.5 385 fon ‘ a i ad 3 ie 8 34 323 “Aas
eee iam eter -+ Parallax — Refraction - + 13.410 13 41.0 13 410 13. 41.0 13 41.0 13 41,0 13 41.0 13 41.0 13 41.0 13 41.0 13 41.0 13 41.0 13 410 13 41.0 13 41.0 13 41.0 13 41.0
_Reduction to noon, - E + 89.5 99,8 194 6.5 25 0.1 11 At 9.6 15.9 24.3, $23 41.3 55.9 1 98 1 363 1 59.201.0%)
Co-latitudes, or height of equator. 34 25 42.0 2539.2 5 25 2 Q 2 B 5 eT
Poste ‘ - 34 2 25 39.2 25 598 25 48.7 25 45.0 25 43.1 25 43.1 25 4B 25 87.5 25 35.7 25 40:8 25 4018 25 34.2 25 40.5 25 36.2 25 36.7 25 43.7
5 - - : 55 34 18.0 34 20.8 34 072 34 11.8 34 15.0 34 16.9 34 16.9 34 16:6 34 22.5 84 24.3 34 19,2 34 19.2 84 25.8 8419.5 34 23.8 34 23.3 $4 163

10th of February, mean of 1% Latitudes, ...../55 34 1816
9th of February, - 17 Latitudes, .....55 34 14.2

MEeEay, 55 34 16.4 Lat. of Makerstown.
SS

* Note. HW becomes — D when the Sun oc Star is North of the Equator.

XV. Description of a Vegetable Impression found in the Quar-
ry of Craigleith. By Tuomas Auuan, Ese. F.R.S.
Lonp. & Epin. |

(Read January 22. 1821. )

I soME time ago had the honour to present to the Royal, So-
ciety, a specimen of a very singular fossil which had been
found in the freestone quarry of Craigleith, near this city.
It presented the appearance so commonly met with in the
sandstone of the coal-formation,—an impression of what has
always been considered as the bark of a vegetable connected
with the Palm-tribe ; but it differed from any thing I had ever
before seen of the kind, by having circular marks ranged in a
line along the surface, being apparently the impressions of
flowers or fruit. As neither of these grow directly from the
stem of any plant now known, except among the Cactus ge-
nus, this impression might have been referred to it, had not
the regularity of distance between these supposed flowers,
pointed out the improbability ; and it consequently must be
referred to some one, the prototype of which is no longer
known.

The size of the specimen, of which the annexed engraving
is a very exact representation, is twenty-one inches in length,

VOL. IX. P. I. cg and

236 DESCRIPTION OF A VEGETABLE IMPRESSION

and about fourteen broad; the widest part of the impression
measures four inches, and the diameter of the circles a little
more than three. On each edge of the mass there are other
impressions of vegetable remains, and in one place some feeble
indications of the same kind as those on the principal sur-
face.

I considered this specimen of so much importance, that I was
induced to request Mr GRrEVILLE to make a drawing of it, with
the view of communicating it to the scientific world ; and I am
happy to acknowledge, that to the distinguished abilities of.
that gentleman, I am indebted for a most beautiful design, from
which the annexed engraving has been made by Mr Lizars.
When communicating with Mr Lizars, on the subject of this
engraving, he shewed me a plate he had executed for the Ency-
clopédia Edinensis, representing a specimen belonging to Dr
Mixrar, similar to my own, which till then I considered
unique. I waited on Dr Mixxan, who politely shewed me his
specimen. It presents a string of five buds: they are smaller
in dimensions, about an inch, or an inch and a half in diame-
ter, but very distinct, set at regular distances, and in all re-
spects quite analogous. This specimen was found in a quarry
belonging to Sir Joun Darrympte, on the ridge a little south

‘of Dalkeith,—where I learn a great many other fossils, and
many curious impressions of plants, are found in great abun-
dance.

It is not my intention to touch upon the interesting specu-
lations which the occurrence of these unknown species of vege-
tables irresistibly opens to the mind. They give us a glimpse
of former periods, which sets conjecture at defiance, and
smiles at the vain attempts of theory to unravel. I only wish
to call the attention of the naturalist, to the advantage which
may be derived from a proper attention to this department of

natural

PLATE XIV. Engraved tor the Royal Sovtety Trans! Vou, page ib:

H
WH)
HH

Wy

RE Greville Delin. Eng thy WHLizars
tue ET ead

FOUND IN THE QUARRY OF CRAIGLEITH. 237

natural history ; and when it is known how much this country,
I may say our immediate neighbourhood, abounds in fossils
of this description, it is rather to be lamented that no exten-
sive collection of them, has been systematically made. In ge-
neral they are much too bulky for usual sized cabinets ; and if
some place were appropriated for their reception in the Mu-
seum of the Royal Society, I have no doubt they would soon
accumulate. For besides in the vicinity of Edinburgh and
Dalkeith, they are found in immense abundance all along the
coast of Fife, down to St Andrew’s. Within high-water
mark near Dysart, there are trees equal in bulk to the cele-
brated fossil lately found in the quarry at Cowcaddens near
Glasgow, which has the strongest possible resemblance to an
oak ; and in the quarry of Cullalo, five or six miles from Burnt-
island, belonging to Mr Stuart of Dunearn, the whole of the
upper stratum of a most extensive field of sandstone, is filled
with them to an extent beyond any thing I have ever seen. It
was in this locality that a specimen was found, which was sent
by Mr Fereuson of Raith to the College; it appeared to be
some species of Reed, of a truly gigantic size ; its form is ellip-
tic, and it measures about a foot by eight inches in diameter,
and is in length seven or eight feet.

Having such stores of these fossils in the immediate neigh-
bourhood, it is no small reproach to us to be without a collec-
tion. On the Continent, I am told, an antediluvian Flora is
now in preparation ; and with such means at our disposal, why
should we not have an antediluvian Hortus Siccus ?

6g 2 XVI.

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ae:

XVI. Account of the Native Hydrate of Magnesia, discovered
by Dr Hisserr in Shetland. By Davin Brewster,
LL. D. F.R.S. Lonp. & Sec. R. S. Epry.

: 4 Read January 8. 1821.)

Tur Native Hydrate of Magnesia was first diseovered, and
ranked as a separate Mineral, by the late Dr Bruce of New
York. It was found only at Hoboken in New Jersey, traver-
sing serpentine in every direction, in veins from a few lines
to two inches in thickness. Its specific gravity was 2.13, and
it yielded upon analysis 70 parts of pure magnesia, and 30 of
water *.

In the year 1813, I received some fragments of this rare mi-
neral from our late eminent countryman Dr Joun Murray,
and though it exhibited no traces of a crystalline structure, I
found it to be a regularly crystallised mineral, with one axis
of double refraction perpendicular to the laminz fT: The con-
nection between the primitive form of minerals, and. their
number of axes of double refraction, which I observed at a
subsequent period, enabled me to determine that the Native
Hydrate of Magnesia belonged either to the Rhomboidal or
the Pyramidal system of Mons.

In

_* See Bruce’s American Mineralogical Journal, vol. i. p. 26.-30.
+ See Phil. Trans. 1814. p. 213., and 1818, p. 211.

240 ACCOUNT OF THE NATIVE HYDRATE OE MAGNESIA,

In this state of our information respecting native magnesia,
Dr Hiszert, who has distinguished himself by his excellent
mineralogical survey of Shetland, and augmented our national
resources by the discovery of Chromate of Iron in large quan-
tities, put into my hands a mineral from Shetland, which had
been considered by mineralogists as White Tulc, but which, he
was persuaded, differed materially in the nature of its ingre-
dients from that substance. In consequence of being familiar
with the Hoboken Magnesia, I considered the Shetland speci-
men as the same mineral; and I put this opinion beyond a
doubt, by establishing the identity of their optical properties,
and also by a chemical examination of the two substances.

Mineralogical Character.—The structure of Native Hydrate
of Magnesia is distinctly lamellar. The laminz sometimes
diverge from a central line, and frequently occur in groups,
with the laminz of one group inclined to those of another,
like the masses of mica in granite.

The colour of the laminz is white, and a slight tinge of
green is sometimes observed, when we look upon that dice!
They are perfectly transparent when separate ; but I have no-
ticed in specimens exposed to the weather, a dull and white
opacity, which had been induced by the separation of the mi-
neral into a greater number of minute laminz. This white
part has the same relation to the transparent part as Albin has
to Apophyllite *, and, as happens with this mineral, the disinte-
gration follows the crystalline structure of the body. One
specimen of this kind exhibited a six-sided prism, the interior
of which was undecomposed, while all the external part had a
white opacity.

The Native Hydrate of Magnesia scratches Talc, from
which it may be easily distinguished, as the former marks

white paper with a silvery powder, whereas the latter gives
only

* See Edin. Phil. Journal, vol. i. p. 5.

Ve —

DISCOVERED BY DR HIBBERT IN SHETLAND. 241

only a polished line, and leaves none of its own substance. Its
hardness seems to be 1.5. ;

In several specimens I have observed a distinct crystalline
structure, in the form of the regular hexahedral prism. The
pyramidal form being therefore excluded, it will belong to the
Rhomboidal system of Mons.

Its specific gravity is 2.336. It adheres very slightly to the
tongue ; and it will constitute a new Genus of the 5th Order,
or that of Mica in the 2d Class of Mons’ system, unless the
order of Talc-Mica is modified to receive it.

Locality.—Dr Hiszertr found this substance, in 1817, at
Swinaness in Unst, one of the Shetland Isles, traversing serpen-
tine in all directions, being mixed with the Magnesian Car-
bonate of Lime, and forming veins from half an inch to six
or eight inches broad.

Chemical Character.—Hydrate of Magnesia dissolves entire-
ly in muriatic, nitric and dilute sulphuric acids, and I obtain-
ed from its solutions in the muriatic and sulphuric acids, the
deliquescent salt of Muriate of Magnesia, and regular crystals
of Sulphate of Magnesia. On some occasions a very slight ef-
fervescence takes place ; but this no doubt arises from adhering
particles of carbonate of lime, or from a small quantity of car-
bonic acid, which may have been absorbed by exposure to the
atmosphere.

The following analysis of this mineral has been made by Dr
Fyre, since the preceding account of it was drawn up :

Magnesia, - 69.75
Water, - - 30.25
100.00

242 AacCOUNT OF THE NATIVE HYDRATE OF MAGNESIA, &c.

a result which differs only a quarter of a per cent. from that of
Dr Bruce of New York.

Optical Structure-—The Native Magnesia has One axis of
double refraction perpendicular to the laminz, and exhibits
the single system of coloured rings traversed by a black cross.
The character of its action is Positive like that of Quartz, and
the tints which it polarises are different from those of New-
ton’s scale, resembling somewhat those which surround the
resultant axes of Selenite*. This mineral is not phosphores-
cent by heat.

Distinctive Character.—The Hydrate of Magnesia is distin-
guished from Talc, by its having one axis of double refraction,
while Tale has two axes;—by its lower specific gravity, and
greater hardness ;—by its marking paper with a polished line,
in place of a silvery one, as already noticed ; and by its solubi-
lity in acids. It is distinguished from the Common Mica with
two axes, by the elasticity of the latter, as well as by its two
axes ; and it is equally distinguished from the less flexible
Mica of Kariat in Greenland, and from other micas that have
only one axis, by that axis being positive in the Magnesia and
negative in the Mica, and also by the character of the tints
with which the axis is encircled.

It is distinguished from Selenite, by its having one axis of
double refraction perpendicular to the laminz, whereas Sele-
nite has two resultant axes lying in the plane of the lamine ;
—by the want of regular cleavages,—and by its solubility in
acids.

* See Phil. Trans. 1818, p. 243.

XVII.

———————

XVII. Description of a Magnetimeter, being a New Instrument
for Measuring Magnetic Attractions, and Finding the
Dip of the Needle ; with an Account of Experiments
made with it. By Wriam Scorzssy, Esa. sun.
F.RS.E. M. W.S. Sc.

(Read January 22. 1821. )

My Dear Sir, ' Liverpool, 9th Jan. 1821.

Axsour ten months ago, I had the honour of communicating
to the Royal Society, a description of a new instrument for as-
certaining the Magnetic Dip. Having made very consider-
able improvements in the apparatus, by means of which some
curious results on the magnetic laws, especially those that relate
to the production and annihilation of magnetism in iron, have
‘been obtained,—I now beg leave to submit to the Society a
drawing and description of my improved instrument, together
with an outline of some of the most interesting experiments
made with it. Many of the results appear to me to be new;
if so, their importance will be my excuse for repeating some
parts of the description given in the former paper. It has

VOL. IX. P. is Hh been

244 DESCRIPTION OF A MAGNETIMETER, BEING A NEW

been long known that iron might be rendered magnetical by
percussion ; but I am not aware that the precise effect of posi-
tion has ever been suggested. I remain, &c.

WiriiAm Scoressy Jun.’
To Dr Brewster, i

Sec. Royal Soc. Edin.

es

From a series of observations on the anomalies in the posi-
tion of the Magnetic Needle on ship-board, made on the coast
of Spitzbergen in the years 1815 and 1817, I was led to attri-
bute the deviation of the compass to the combined attraction of
all the iron in the ship having a vertical position, as it appear-
ed that, in high latitudes, horizontal bars of iron had scarce-
ly any influence on the needle. The result of my investiga-
tions, with the several inferences drawn from them about the
time of observation, were published in the Philosophical Trans-
actions for 1819. In the present paper, therefore, it is my
intention only of communicating to the Royal Society some
curious facts which have arisen out of a further investigation
of the subject.

For examining into the phenomena of the polarity of iron
arising from position, &c. I constructed, about the month of De-
cember 1819, an apparatus, of which, with improvements recent-
ly made, the following is a description. It consists of a small
table of brass, A, Plate XIII. Fig. 1., 4; inches square, and 33
inches high, having a plate of brass C attached to it by hinges,
and moveable by means of the wheel and pinion D, E, through
an arch of 250 degrees of a vertical circle. This plate has a
small straight groove running from end to end, in the line aa,
for the purpose of receiving bars of metal, the polarity of which

is

INSTRUMENT FOR MEASURING MAGNETIC ATTRACTIONS, &c. 245

is to be determined. These bars are readily fixed to the plate,
by being slipped through a circular aperture in the end of a
spring 5, which, perforating the moveable plate, and acting
downward, firmly embraces any substance laid along the
groove. The angular position of the moveable plate is mark-
ed by a circle FF, screwed upon the side of the table. It is
graduated so as to mark the angle between the moveable plate
and the horizontal plane, whether above or below it.!, To! in-
sure accuracy in this angle, the true horizontal position of the
table, and with it the horizontal line on the circle, is determin-
ed by means of 4 spirit-level G-;'and that: the movements of
the plane may be accurate, and the angle marked true, the pin
which passes through the hinges also forms the centreof the
wheel D, and terminates‘exactly in the centre of the graduated
circle F. H is a- moveable flat plate of brass, divided into
rhumbs and degrees : it’ is furnished’ with a magnetic needle,
having an agate cap ‘traversing on 4 brass or steel point. The
needle can be changed according to the nature of the circum-
stances ; a very light and strongly magnetized one being used
in delicate experiments." The compass or plate carrying the
needle, being moveable, its distance from the bar resting on
the limb C, can be varied at pleasure. The centre of the
hinges is one-tenth of an inch above the level of the table ;
the magnetized needle stands at the same elevation ; and the
bars in use being one-fourth of an inch diameter, are sunk in’
the groove of the moveable plate to such a depth, that their
axis, or centre, precisely corresponds with the centre of the
hinges ; hence the middle of the extremity of each bar is at the
same elevation, and at the same distance from the needle in
every position of the moveable limb. To give firmness to the
instrument in making experiments, the table is fixed by the
feet to a mass of lead I, of seven or eight pounds weight. By

Hh 2 means

246 DESCRIPTION OF A MAGNETIMETER, BEING A NEW

means of this plate of lead, which has a screw d at each cor-
ner, the whole apparatus is readily put into a horizontal po-
sition. As the instrument is put together by screws, it can
be easily taken to pieces, so as to become exceedingly por-
table.

Hitherto this instrument has been principally used for esti-
mating the magnetism of position in iron,—for ascertaining
the existence of permanent polarity in iron or steel,—for mea-
suring and comparing magnetic attraction or repulsion, as pro-
duced in iron by certain means independent of the magnet,—
and for determining the magnetic dip.

From ignorance of, or inattention to, the magnetism of po-
sition, various erroneous conclusions have been drawn and
propagated respecting the phenomena of the magnet. For in-
stance: In several popular works on this subject, that I have
consulted, it is stated, that ‘ if an iron-bar have gained a ver-
ticity by being heated red-hot and cooled again, north and
south, and then hammered at the two ends, its virtue will be
destroyed by two or three smart blows on the middle *.”
Now there is a particular case in which this may be true; but
most generally the statement is inaccurate: for by hammering
a bar of iron at the ends, or in the middle, magnetism may be
destroyed, produced, or inverted, according to the position in
which the bar is held. The effect of position is indeed such, that
a bar that has been presented to a magnetic needle, and found
free from magnetism, when presented a second time, a quar-
ter of an inch nearer to the needle, or at an angle a degree or
two nearer the horizontal, may appear to have gained south

polarity,

* ‘Bes Hurron’s Math, & Phil. Dict. &e. article Magnet.

INSTRUMENT FOR MEASURING MAGNETIC ATTRACTIONS, &c. 247

polarity, by attracting the north pole of the needle. With
this instrument, however, pieces of iron or steel, after having
their state as to magnetism determined by it, and being then
submitted to any operation capable of affecting their polarity,

*can be brought a second time to the same precise position,
can be presented at the same angle to the needle, and can have

any change in their polarity determined in the most satisfac-
tory manner.

As a substitute for the dipping needle, this instrument be-
ing much less expensive, and much more portable, may be
considered, perhaps, of some importance. The situation in
which bar-iron, void of permanent polarity, loses its magnetism
of position, is the plane of the magnetic equator. The obliqui-
ty of this plane, measured from the horizontal, is, in London,
19° 26’, that is, in the line of its axis coinciding with the mag-
netic meridian. It dips towards the south, and is horizontal
in the east and west. The obliquity of the magnetic equator
being the complement of the dip, and my magnetic apparatus
enabling us to discover that obliquity, by pointing out the
angle of no-attraction in iron, we are furnished with a simple
process for determining the dip of the needle *.

By means of this instrument, several curious results, in the
phenomena of magnetism, have been obtained. The experi-
ments were chiefly made on small bars of iron and steel, laid
in the groove of the moveable plate. As the instrument, at
the same time, was placed in a north and south position, ac-
cording to the compass, the bar, on being elevated or depres-
sed, traversed in the magnetic meridian. The moveable limb

az was

* The remarks subjoined to No. 2. -of the succeeding “propositions point out

the method of finding the dip, and show what precautions are necessary to be
used to insure accuracy in the result,

248 DESCRIPTION OF A MAGNETIMETER, BEING A NEW

was usually directed towards the north. our bars were prin-
cipally made use of. No. 1., consisting of a piece of iron-
wire, softened by heating, a quarter of an inch in diameter,
and six and a half inches long. No. 2., another piece of wire,
of two-tenths of an inch diameter. No. 3., a cylindrical bar*
of hardened steel magnetised, of the same dimensions as No. ].
And, No, 4. a similar piece of steel softened by heating to red-
ness. With these, and the instrument already described, a
great number of experiments were made ; the results of which,
in the form of propositions, are annexed ; and as almost every
experiment was repeated a. number of times, I can give the re-
sults with the utmost confidence. What is called the Magne-
tic Axis in the following propositions, is to be understood as
the position pointed out by the dipping needle ; the Magnetic
Meridian is a vertical plane in the line of the magnetic north
and south; and the Magnetic Equator is an oblique plane, to
which the magnetic axis is perpendicular.

PROPOSITIONS, gc.

1. Iron bars become magnetical by position, excepting when
placed in the plane of the magnetic equator; the upper end,
as regards the position of the magnetic equator, becoming a
south pole, and the lower extremity a north pole.

Experiment 1—Bar No. 1. placed in the groove of the moveable
limb, with the compass [H] at the distance of 11 inches from its
extremity, and the instrument north and south, (as in Fig. 3.) :
did not disturb the needle at the angle of 20°; but raised to an
angle of 46°, it repelled the north end of the needle one point,
f11° 15’], and at an angle of 73° two points. The north end of
the plate being depressed 25° below the horizontal, the bar in-
stantly exhibited an attraction of one point. ‘Though the bar
was then changed end for end, still the same results were obtained.

Exp. 2.

INSTRUMENT FOR MEASURING MAGNETIC ATTRACTIONS, &c. 249

Exp. 2.—A bar of cast iron of the same magnitude was found to pos-
sess much less magnetism of position than the above. With the
compass: 13 inches from the end’ of the bar; No, 1., produced a
deflection of 11°, when elevated 29+ above the plane of no-attrac-
tion: while the bar of cast iron, though of a soft kind, required to
he elevated 68° above the plane of no-attraction, before an equal
repulsion was produced. When the bar No. 1., was raised to the
angle of 68° above the plane of pall it repelled the com-

_ pass-needle 27+.

Exp. 3.—Tron-bars of similar thickness, but of unequal lengths, were
found to possess different capacities for magnetism of position.
Thus a bar one-fourth of an inch in diameter, and nine inches
long, elevated 70°, caused a deflection in the compass-needle of
23° 45'; the same reduced to 63 inches long, then repelled the
needle 18+; and a portion of the same 23 inches long, only repel-
led the needle 7° 30’. ,

2. No attraction or repulsion appears between a magnetised
needle and iron-bars; the latter being free from permanent
magnetism, whenever the iron is in the plane of the magnetic
equator 5 ; consequently by measuring’ the angle of no-attrac-
tion, in a bar placed north and “south, we discover the magne-
tic dip.

Exp—With one end of the bar No. 1. compass 23 inches distant,
the elevation of the plane of no attraction, at Liverpool, was 20°,
with the other end of the bar 174°; the mean or co-dip 183°; dip
71°t., On the coast of Greenland, in July last, Latitude 70° 36,
Longitude 17° 30° W. the mean angle of no attraction was 14:,
making the magnetic dip 76°.

Remark.—For the purpose of making use of this instrument for
finding the dip, it is necessary to employ a very small needle, in
comparison of the bar of iron, and to place the needle as far distant

as it will conveniently act; otherwise the magnetism infused into
the

250

DESCRIPTION OF A MAGNETIMETER, BEING A NEW

the bar by the needle, will be mistaken for the magnetism of posi-
tion, and give an erroneous result. Thus, in the preceding ex-
amples of dip, the needle in use being too large and powerful, the
results, especially the latter, are probably a little too low. The
nature of this error will more particularly appear from the next
proposition.

Note.—When a sufficiently small needle is not at hand, the amount

of error in the observed dip, occasioned by the magnetic influence
of the needle on the bar, may, in all cases, be determined by ex-
periment. For we know that the plane of the magnetic equator
coincides with a true horizontal plane, in an east and west magne-
tic line, consequently, when the instrument is placed east and
west, the plane of no-attraction should be horizontal. But, if the
instrument be placed in this position, with the compass-needle at
right angles to the end of the bar, as in Figure 2. it is found that
the infusion of magnetism from the needle makes the plane of no-
attraction something above the horizontal. This angle, measured
from the plane of the magnetic equator, (instrument E. and W.)
is the correction to be applied to the co-dip, observed with the
compass-needle at the same distance from the end of the bar, with
the instrument N. and S., as in Figure 3. Thus, with the instru-
ment N. and S., and the north-pole of the compass-needle eight-
tenths of an inch from the end of the bar No. 1., the mean angle
of no-attraction was 26°; and with the instrument E. and W.,
compass same distance, the angle of no-attraction was 7° 30 above
the horizontal. Now, were the magnetic dip 90°, this would be the
correction to be made use of; but as, in the present dip, the moveable
plate of the instrument, when E. and W.., traverses obliquely to the
magnetic equator, while in the N. and S$. direction it moves perpen -
dicularly to it, the observed correction must be reduced, so as to
give the angle formed with the magnetic equator. In this opera-
tion, radius is to the sine of the dip, as sine of the observed cor-
rection (or angle of no-attraction with the instrument E. and W.)
to sine of the true correction, to be applied to the co-dip, observed
with the instrument N. and S. Hence the above observed efror

of

INSTRUMENT FOR MEASURING MAGNETIC ATTRACTIONS, &c. 251

of 7°30’ thus reduced, calling the dip 71° 30’, gives the true cor-
rection 7° 6’. ‘This subtracted from 26°, the observed co-dip, leaves
18° 54’ for the inclination of the magnetic equator, which, I be-
lieve, is not greatly wide of the truth.

3. Before a magnet can attract iron, that is totally free from
both permanent magnetism and that of position, it infuses in-
to the iron a magnetism of contrary polarity to that of the at-
tracting pole.

Exp. 1.—Bar No. 1., with the compass half an inch from it, had no
attraction or repulsion when the bar was at a mean angle of 351°;
the same bar, with the compass at +ths of an inch distance, gave
the mean angle of no attraction 273°; at 14 inches distance, 24°;
at 22; inches, 201°; and at 2-4 inches distance, the mean angle
of no attraction was 191°. This change, in the angle of no attrac-
tion, with the distance, evidently shews that some magnetism of
position was necessary to counteract the magnetism communicated
by the needle, which was considerable when very near, but became
scarcely sensible at the distance of two or three inches.

Exp. 2.—To prove’ that the magnetic needle, at short distances,
» comunicates magnetism to the bar, until it is balanced by the
magnetism of position, I placed the compass 14 inches from the
bar No. 1. and found the mean angle of no attraction to be 24°;
then placing another small needle at the same distance from the
bar, with its north pole abreast of the north extremity of the bar,
I found the angle of no attraction changed to 201°. In this case,
magnetism was communicated by the needle to the north extremi-
ty of the bar, and the same polarity by the other needle to the
south end of the bar, so as to counteract the influence of each other; .
hence, had the magnetic power of both needles been the same, the
bar would have been freed from all communicated magnetism but
_ that of position, and would have pointed out the true line of no
} attraction.

' VOL. IX. P, L. Li 4,.A

252 DESCRIPTION OF A MAGNETIMETER, BEING A NEW

4, A bar of soft iron, held in any position, except in the
plane of the magnetic equator, may be rendered magnetical by
a blow with a hammer, or other hard substance ; in such cases,
the magnetism of position seems to be fixed in it, so as to give
it a permanent polarity.

Exp.1.—Bar No. 1. freed from magnetism, and held perpendicularly
in the hand, was.struck a smart blow over the upper end with a small
hammer; though it had previously evinced no attraction for the
compass-needle 11 inch distant, when the elevation of the move-
able plate was 212°, the upper end of it now attracted the north
pole of the needle upwards of a point, at the same angle of eleva-
tion. The lower end of the bar produced an equal repulsion.

Exp. 2.—The same bar was now inverted, held as before, and a blow
again struck on the upper end. The poles of the bar were found
to be reversed; that which was before north had become a south
pole.

Exp. 3.—Many more experiments were made on the effect of blows,
from which it appeared, that when the iron was held‘ in or near
the position of the magnetic axis, a blow on any part of the bar,
struck in any direction, or with any hard substance, such as a ham-
mer, a piece of copper, brass, or ivory, or even with a bit of wood,
invariably rendered the bar magnetical, the upper end becoming a
south, and the lower end a north pole. In these experiments, the
iron, when struck, was held nearly vertical in the hand, without
resting on any thing; yet both ends seemed to acquire an equal
degree of magnetism.

Remark.—The fixing of the magnetism of position in iron or steel
by hammering, may be employed with advantage in the experi-
ment of producing a magnet, with the use only of unmagnetised
bars of steel and two rods of iron. For in the commencement, the
bars of iron and steel may have permanent polarity given them by
hammering in a vertical position, by which the process will be con-
siderably shortened. '

5. An

INSTRUMENT FOR MEASURING MAGNETIC ATTRACTIONS, &c. 253

5. An iron-bar, with permanent polarity, when placed any-
where in the plane of the magnetic equator, may be deprived
of its magnetism by a blow.

E’xp.—Many experiments were made on the effect of blows on iron
in this position: the result was always to diminish the polarity,
and generally wholly to destroy it. It commonly happens, that a
single blow with a hammer is sufficient for destroying the magne-
tism of the bar; but if it have been strongly touched with a mag-
net, it may require two or three blows at each end.

Remark.—F or freeing iron of magnetism, it is generally reeommend-
ed to heat it to redness, and allow it to cool in an east and west
position ; but as this process oxidizes the metal, and is attended
with loss of time, the action of the stroke of a hammer is certainly
preferable, and is much more effectual. Where there is no proper
instrument for ascertaining the elevation of the magnetic equator,
along its north and south axis, the effect of blows on the magne-
tism of iron, may be shewn with tolerable precision by 2 common
pocket compass, or other small magnetic needle. Place the com-
pass on a table, whose surface is pretty nearly horizontal, with the
needle corresponding to the direction of the north and south line
of the graduated plate, where there is no card; and then place the
iron, the magnetism of which is to be determined, on the table, at
right angles to the north extremity of the needle, and an inch or
two distant from it, in an east and west position, marking its si-
tuation, either by a line drawn on the table, or by two brass pins.
The iron being now in the plane of the magnetie equator, will
produce no derangement in the needle, if it be free from perma-
nent magnetism ; but after being hammered in the magnetic axis,
on being brought to the same position again, with regard to the
compass, the end of the bar that was upward during the hammer-
ing, will be found to attract the north end of the compass-needle :
If hammered again, when laid horizontally, and pointing east and
west, its magnetism will be annihilated.

112 6. Iron

254 DESCRIPTION OF A MAGNETIMETER, BEING A NEW

6. Iron is rendered magnetical if scowered or filed, bent or
twisted, when in the position of the magnetic axis, or near this
position ; the upper end becoming a south pole, and the lower
end a north pole; but the magnetism is destroyed by the same
means, if the bar be held in the plane of the magnetic equa-
tor,

Exp.—Numerous experiments were made on the effect of these diffe-
rent kinds of treatment: the result, though varying a little as to
the intensity of the magnetism produced, was always the same as to
its quality. Any kind of shock, it seems, is sufficient to render iron
magnetic. A bar [No. 1.] dropped on its end from the height
of three feet on a carpet, became sensibly magnetic ; and dropped
on a stone received strong polarity, the lower end in each case be-
coming a north pole: the same bar then dropped horizontally on
the floor, in an east and west line, so as to strike the ground in the
plane of the magnetic equator, was immediately deprived of its po-
larity.

7. Iron heated to redness, and quenched in water, in a ver-
tical position, becomes magnetic ; the upper end gaining south
polarity, and the lower end north.

Exp.—Bar, No. 2. after being deprived of all magnetic virtue, was
heated red-hot, and quenched in water, in a vertical position. The
lower end was then found to repel the needle of the instrument,
when the moveable plate was in the plane of the magnetic equator,
8°; the upper end attracted it about the same quantity.

g. Hot iron receives more magnetism of position than the
same when cold.

Exp.—The contrary of this has, I think, been generally assumed.
The experiments, however, were most decisive. -Aniron-bar, No. 2.
in a vertical position, at right angles to the north end of the needle,

5 and

INSTRUMENT FOR MEASURING MAGNETIC ATTRACTIONS, &c. 255

and 1} inches distant, produced a deflection of 273°. The same
heated to redness, and then presented in the same position as be-
fore, produced a deflection of 60°. On repeating the experiment
with the bar a little nearer to the compass, the mean deflection of
both ends of the bar was 15° when cold; but when heated red-hot,
the mean repulsion was 77°.

Remark.—On trying the effect of heat on a magnet [bar No. 3.]
its power was found to be permanently weakened by heating to
300° or 400°; but, from several experiments, it appeared that the
magnet atttacted and repelled as much when hot as cold.

9. A bar-magnet, if hammered when in a vertical position,
or in the position of the magnetic axis, has its power increa-
sed if the south pole be upward, and loses some of its magne-
tism if the northend be upward.

Exp.—The compass being placed at the distance of 44 inches from
the south end of the magnetic har No. 3., while the bar was laid
on the moveable plate of the instrument, at an angle of 211°, the
needle was drawn from its meridian 22°. The bar being then
struck ten smart blows on the end with a hammer, south pole up-
ward, its attraction was found to be increased to 26°; ten more
blows increased it to 28°; twenty more to 31°; after which-
there was little change produced, though forty more blows were
struck. The north end of the magnet was now found to repel the
needle 174°.. On striking this end, while held in the hand, north
pole up, after ten blows of the hammer, it only repelled 14°; and
the south end, which had not been struck, attracted the needle 3°
less than before.

10. A bar of soft steel, without magnetic virtue, has its
magnetism of position fixed in it, by hammering it when in a
vertical position ; and loses its magnetism by being struck
when in the plane of the magnetic equator.

Remark.

256 DESCRIPTION OF A MAGNETIMETER, BEING A NEW

Remark.—The effect produced by hammering iron, occurs also in
steel, but with this difference: one blow is generally sufficient to
change the poles of iron, that has been rendered magnetic by
hammering, or to deprive it of magnetism after it has acquired
polarity ; but in steel, it frequently requires two or three or more
strokes of the hammer, before the effect be fully produced.

11. An electrical discharge, made to pass through a bar of
iron, void of magnetism, when nearly in the position of the
magnetic axis, renders the bar magnetic the upper end be-
coming a south pole, and the lower end a north pole; but the
discharge does not produce any polarity, if the iron be placed
in the plane of the magnetic equator. The effects appear to
be the same, whether the discharge be made on the lower or
upper end of the bar, or whether it is passed longitudinally or
transversely through the iron.

Exp. 1.—Bar, No. 1. freed from magnetism, and placed in the posi-
tion of the magnetic axis, received the shock of a Leyden jar, on
its upper end from the positive electricity, by which it was render-
ed magnetic, the lower end being found to repel the north pole
of the compass needle of the magnetimeter, about 3°. This
experiment varied by giving the shock to the lower end of the
bar, and also by passing the discharge transversely, first through
the upper end, and then through the lower end, still gave similar
results, the lower end of the bar in each case repelling the north
pole of the needle“4° or 5».

Exp. 2.—With the friendly and valuable assistance of Dr TraiL1,
(with whose excellent apparatus all the electrical experiments were
made,) several discharges of a battery of sixteen jars were passed
through the iron-bar, when in the same position and circumstances
as in the last experiment. (1.) The lower end of the bar being
connected with the outside of the battery, and the discharge from

_ the inside of the jars being made on the upper end, the magnetism
acquired was such, that the lower end of the bar repelled the
needle,

°
=.

Le Pee

INSTRUMENT FOR MEASURING MAGNETIC ATTRACTIONS, &c. 257

needle, in one experiment 10°; and in another 14° or 15°. (2.) The
bar, freed from magnetism, and the shock of the battery received —
on the lower end of it, it repelled the needle 16°. (3.) A dis-
charge taken from the outside of the j jars, the lower end of the bar
being connected with the positive electricity, gave a repelling
power of 15°.

Exp. 3—The bar was now placed horizontally, pointing east and
‘west by the compass, consequently in the magnetic equator. In
this position, the discharge of an electrified jar sent through it,
produced no magnetism whatever, and the effect of the battery
was scarcely perceptible. The slight deviation of the needle, in-
deed, after one discharge of the battery, is to be attributed to some
accidental circumstance; probably the bar was not accurately in
the magnetic equator.

12. A bar of iron possessing some magnetism, has its pola-
rity diminished, destroyed, or inverted, if an electric discharge
be passed through it, when it is nearly in the position of the
magnetic axis, provided the south pole of the bar be down-
ward; while its magnetism is weakened or destroyed, if it re-
ceive the shock when in the plane of the magnetic equator.

pene 1.—The bar, No. 1., having such a magnetic influence’ as to
produce a deflection of the compass needle of 10°, was. placed in
the direction of the magnetic axis, north pole upward. A shock
from the battery being then passed through it, the whole. of its
magnetism was found to be dissipated. The discharge of one jar
on the bar, when slightly magnetised, with its north pole upward,
had a similar effect ; only in ‘some instances, the magnetism,
though weakened, was not wholly destroyed.

Exp. 2.—The bar being in the plane of the magnetic equator, and
having such polarity as to produce 10° deflection of the needle, had
a charge of the battery passed through it, by which its power on

_ the needle was reduced to 2°. The shock of a single jar, produced
in some degree a similar effect.

13. Iron

258 DESCRIPTION OF A MAGNETIMETER, &c.

13. Iron is rendered magnetical, if a stream of the electric
fluid be passed through it, when it is in a position nearly cor-
responding with that of the magnetic axis; but no effect is
produced, when the iron is in the plane of the magnetic equa-
tor.

Exp. 1.—Bar, No. 1., freed from magnetism, and placed upright in
the prime conductor, had a silent stream of electricity drawn from
it by Dr Traix1, first with a poimted wire, and then with the
point of a cone of wood. In both cases the upper end became a
south pole, and the lower end repelled the needle 6°. Sparks drawn
from the bar by a piece of metal answered the same purpose.

Exp. 2.—The prime conductor being turned into an east and west
position, the bar was introduced into an orifice in the end of it, and
consequently obtained the position of the magnetic equator. A
stream of electricity drawn from it with a cone of wood, or with a
piece of metal, did not render it at all magnetic

$i

Some experiments of a similar nature to those which are gi-
ven in illustration of the last three propositions, were attempt-
ed with a galvanic apparatus, for the purpose of ascertaining
whether some of the electro-magnetic phenomena, lately ob-
served by Mr Orrstep, be not referable to the position of the
iron or steel made use of in his experiments ; but the power
of the apparatus I employed, though sufficient to produce stri-
king effects on the position of a compass needle, was not ca-
pable of magnetising iron; consequently the experiments
made with it did not prove satisfactory.

XVIII.

XVIII. Account of the Establishment of a Scientific Prize by the
late Avexanver Kertu, Esq. of Dunottar. In a
Letter from the Trustees to Sir WatTER Scott, Bart.

i P. RS.

(Read December 18. 1820.)

GENTLEMEN,

Ir is no doubt already known to you, that the late ALExan-
vER Keitx, Esq. of Dunottar, bequeathed the sum of L. 1000
for the purpose of promoting the interests of Science in Scot-
land. Having been appointed Trustees for the Management
of this Fund, we have endeavoured to appropriate it in the
most advantageous manner for the advancement of Science ;_
and we have the satisfaction of stating, that the plan which has
been adopted met with the special approbation of Mr Kerry
_ himself, to whom it was communicated previous to his death.

As the Royal Society of Edinburgh is the principal Scienti-
fic Establishment in Scotland, we hereby offer to its President
and Council the sum of L: 600; the principal of which shall
on no account be encroached upon, while the interest shall
form a Biennial Prize for the most important discoveries in
- Science, made-in any part of the World, but communicated by
their Author-to the Royal Society, and Papucnes for the first
time in their Transactions.

VOL, IX. P. I. Kk With

260 ACCOUNT OF THE ESTABLISHMENT OF A SCIENTIFIC PRIZE

With regard to the form in which this Prize is to be ad-
judged, we beg leave to suggest, that it may be given in a
Gold Medal, not exceeding 15 guineas in value, together with
a sum of Money, or a Piece of Plate, bearing the devices and
inscriptions upon the Medal.

If, during any of the Biennial Periods, commencing from
Martinmas 1820, no discoveries of sufficient importance shall
be communicated to the Society, the interest of the Fund may
be added to the principal, after paying the incidental expences
incurred, from the preparation of the dies and other causes.

Leaving all other arrangements to your judgment and dis-
cretion, we have only to express the hope, that this Donation
may realize the Patriotic Views of its Founder, and contribute
in an eminent degree to advance the honour and interests of
our native Country. We have the honour to be,

GENTLEMEN,
Your most obedient,
Humble Servants,
Avex. Kerru.

J. Kerru.
Davin BrewsTeEr..

EpIngurGH,
Dec. 4. 1820.

To Sir Watter Scott, Bart. PresipEnt,
and the other Members of the Council
of the Royal Society of Edinburgh. _

RESOLVED,

BY THE LATE ALEXANDER KEITH, ESQ. OF DUNOTTAR. 261

REsoLveED,

That the President and Council of the Royal Society of
Edinburgh, cannot forget the zeal with which their late vene-
rable Associate, Mr Krrtu of Dunottar, pursued every object
that could forward the discovery and the dissemination of
knowledge : and they receive the gift which has been announ-
ced by his Trustees, under the conditions prescribed, with sen-
timents of the most respectful remembrance and gratitude, and
with the determination that the intentions of Mr Kerrru shall
be fulfilled, in a manner, it is hoped, which will do equal ho-
nour to his Memory, and to the future successful Candidates
for the distinction of the Kerra Medals..

RESOLVED FURTHER,

That this resolution be transmitted by the President to the
Trustees of Mr Kerru, and that these Gentlemen be at the
same time requested, to accept the thanks of the President
and Council, for the trouble they have so obligingly taken on
the present occasion.

Roya Society ey
Dec. 18. 1820.

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PLATE XVII

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Paves: «! %
Re he N £
See eS inky © ee ‘eee
eS ee 2 ¥ ee. & e “eat > - € 3
ee XIX. On the Mineralogy of Disko Island. By’ Sir Coalre
a ak Guesecke’ F. RS. Edin. M-R, 1. A Professor of Mines: “et
| me sialogy to t the Royal Dublin Society, and Member of the | &
ton, sd ye ae ak Societies of Co “ee i pase, &c. &c. J ae: - oe F
4 kote yc! . id i ‘e a itt iad
eh cine ‘ . ie
ag ina nm. ha Saris 4 1814.) ¥ a oe Mp
© “ i 5 Be % 4 oi hs r a AY x
fin ta r > = * et x we 4
er Lye ipa Coal WMS a
on” . JISKO 1 Islarid; (eee iat OXY. vis Wigseds in front of a bay ae be
em int ie capita within Davis’ Strait, known b: . Sa
: - athena me f,Disko Bay, which is sometimes called, 12 ae ¥ + woo s
pet “in fd charts, ‘Sydost Sir, This: name is detived from. 5 op a ae
unyaturé,Screened by iqnuniffeble islands,made in Pe ; iz

a z
sites singel the seas! Disko Island situated in 69° 14’ of N. te el ¢ aif
. aeae distant from t cn towards the south 2. .3 gf on ’
miles son the west” d itis surrounded: by-thé + air o, a, .
_ Ben of Davis! it ; and on the east, it is‘Separated by @ oer nf wa , = 4
Jdistinguis red by the nate of Waygat'by the, Dateh, * A a Sally ye
by the Greenilan 3 Ikareseks Ik. » It stretches. novth.z" +.., $s Se
hee ‘from 69° 14'9t0'70° 24%, and: its “greatest, breadth, which b= te Re /
sf ere Bay on chert ‘west, to Flakkerhuky’ ‘so named aye. *y he 3° /
Dutch pnts 2 east, ig 10 German’ miles. os | a ei, was Fy Se > Ses
. * She mol of Disko Island belongs: to the Reigtan tin, © Mi Ys Sas steit
mst , which extends. over- part of. the cotitinenty beyond the), m PS a a 4g ‘€ 3
-& Way nd ‘shews - itself onthe other side at 69%. 20°F NS;

af bea

ee ey y ote % rs 7 7s 3,
4 be Lat. finuing towards and occupying | the penin sila oP Noon ‘oy x rab .
Soa, which Ba arates | Disko Bay from the Bay ‘of: f, St Tames, ee wd ‘Nii
4 ,« eeiled by thie tch Stikkkende Jakob's Bay. On the‘edst end" <* 3
) eee PE Poe 2 nel gag ta aie 5 EIN ve ak ok
% ie * ith ‘sy oy” ae 2 “nh <9 bs = a Pe i”
ae ; a Me hans niga
<< vg eed . é Ry ¢ 7 ae, ‘ad ee j

> ue. "ae. oe hy ts cs , fy vite a . $5 eco % "ings oi ie : Pa ©
maar yf ‘ wt hs 5 ee ee rie nae aa Eva ; “y * *, me S ee ee
; 5" oe Pee of: this paygthotigt ie disapp ears. “under. ‘the stuperidois |
eh _ % . _ glacier or. ice-blink oft sim arm of the s , sea; and. on the. i
% opposite'side of ‘itsnot the smallest vestige of Alcetz-trap is is tobe oe
‘ discoysren; On quitting the shore, however, towards the north, * +e
- the same formation’¢ occurs, at the i island of U; Upernavik or Spring: 4. :
"se Island, wihiich is formed of basalt, with immense beds of sand-
stone containing \ veins of brown and. bituminous wood-coal. ~
Gs -aTwo considerable islan situated beyond the Frith; one nanied .
ih Ubekjendte or Unknown Island, and the other Hasen or. are 2.
™ Island, belong also to the floetz-trap, + #. " -
i ey ie Se ss
ye These islands, although now detached, all Woy have orig
7” ginally belonged to theygame mass, and ay! have been torn”
> > asunder by the inipetuosity of the sea, which; impelled by thes).
oie , ae winds from, every quarter;) runs with, a * almost b onde! J:
a belief uring su¢h a tempest, ae ave myself'seen chalga ‘
oh 2 yt: cof thé great Greenland whale, Bal oh thrown to a Oh
oii ® or pegs of 200 feet inland’ upon “2 snk = oe a "4
x f ~, Beyond the Bay of St James, towards. sg Northerd +. J
‘y e 4 % Pine called Svartenhuk, the etz-trap is inte pted, either by: “s

amense > plain covered with, al- ye

> | i Ps _ oe Joke Svartenhuk i is composed a a granitic rock, with’ a3

j @ © ~ large beds of smicaceous schistus, mixed with Lies i .
2 win re #y Inthe adjacent bay, c called Hytten, the floetz-trap sh itself in e%,
. a Pk hl _ small hills, eee: a bed of sandstone, in ich vitae q
sense 4 # “wood ovens. From this point, the continent of Greenland,

% ie op ag > «whieh consists of granite, stretches awayyto the east of north," *
% _— ne ee is, covered. with» an - incredible number of sm all islands, me
+! EF Oe scalled “the. Vrowen or. Womens’ Islands, The base of these .
ai “sisla nds. is, uniformly. granite or gneiss; the last sometimes, >. af

al WS «—@% pthe primitive rocks, or by an

* thoughemarel ‘mixed | with garnets. ‘Some art the islands Is are. Kod

covered with | beds-of the floetz aprteacien Bear Kakar-,

£3
2 ta ak, the laxgest.of | the ; FOUR eae ee ec. Sh fae
rac ” & 4 my Bey an ‘rae! » « “gh » beer 2 7 iM a . a
so se ig Oh TOF a 3.30 ; 33
fs : tae ee * Pret a ¥" 4 uy ak 8 ; i, ¢ La
- — > - 3 ~A ~ _ on ws *,
Key OF Py LS es 1 eee ‘
Recs a ee ee :
Ky Bey af eae She oe ge
s owl P™ soe = 2 ne gi% 5
me 3s 4.05 x ae Pine - . tin ? c
Pe Bee et as > Bite . :
igty ¥h Coy at . va y > * F ’ »
a ge ape’ Be *

-

** . — P { ~ ’ , ~, ‘ A

‘Sys Pes t, ae, Sere aR Pal iets i! %
RR See: : or DISKO ISLAND. a ak bs 265
RS eae Rear So: rae

+

= Lat. 72° 32’, the. Alocta-trap again disappears, and granite, ale
- ., térnating with ‘gneiss, present themselves, and ¢ontinue ’ to

+ * * Near Cape Nullok, in Sanderson’s Hope the fleetz-trap.a ain
td ; i Pex page:

e+ appears in large thasses of columnar basalt, resting On gneiss ;

% Be. “but beyond this place, there'is no farther approach, the coun?

Pa % To the soith of Ieiagials in the ‘colony of Upetnavik, i in $

as 4 + Lat. 73°-32’,.at the islands of Usdjordlersoake and” ‘Tessiursak?

*. ge try being e294 by the ies Boreal Glacier,—the Norther” ’

% Icedlink. * :
ie % *E : The diedetion of’ the trap-rodks, fvhick are ae siren over
- such™ an, extent,of country, is. almost entirely similar, being

“s.@ nearly horizontal, stretching. from south-west. to’ flortiibast.
* ©The beds.of which they. are Composed are of a very unequal
thickness: those of basalt are most prevalent. "The hills com-

PRS La

"ways slightly decomposed upon’ the surface; where in contact
i the-trap. ©The: prismatic basalt of this district, is of that.
ecies “distinguished in. Germany by. the ‘name. of’ Basaltic
xreenstone, ( Griinsteinartiger Basalt). It is almost: pure, but”
“sometimes contains a few detached specks; perhaps crystals of”

‘ “and of. hornblende. “The massive basalt, on the contrary, often

* becomes amy edaloidal, by the small globules of mesotype, stil- ”
|p bite: and quartz which. it) contains, Itoceurs very generally

¥ undermost, and” touching the primitive rocks, which is very

_ ©) arely the case with the columnar basalt. .

~) #The Trap-tuff, ‘which is very common among the floetz rocks
of Disko, tests’ also: always immediately’ on the primitive rocks :
Indeed, I never found it in any other situation in’ that island,
‘It appears’ ‘to me. here necessary ‘to’ mark two varieties” of »

% oe: che rock, namely; that which consists, aBmost. entirely of. frag

$a3% 2

Br. eS
* rg nae Le Wt ep Brat : ments
St . ei et
, a ‘ 7 AR
a 86 6+, a , oe ee ee J 4 * ed
rs ee ht ” * #
a 4 ~ > af tie 5 eR sgt ay °F
ss ¥ ae, - *, *. * G _
‘wes eS “x. 2 ay t ~~ %, ¢
Ne ‘ ” . es vo _* we
+ « rs oa ~ ee %. ,
a a & oe > k 4 ee
mY % ‘st an > &
‘ ‘ oe
» 5 ae rm

> posed’ ‘of gneiss and. granite are neyer highly elevated ; ‘andthe
et floetz. rocks. are ‘placed immediately on the gneiss, which is al.”

, @elspar! T found only in one place some small grains of augite _

o

opin Maxed
Ph:

MA) :
aa ft
eR Se
<% stig D
-
*
“s €
; x
t ok 2
Se . &
eh
£
- ‘ -
ss eae Lg
5 ae *
% ae. ty, &
et UN ¥¢
Ong EF Aas

4 - “ a #. $ ow . bd
n € 7 ee se ace’? ; a ag Vel A er. %
F bs 18% 5 ie » ot a “ig +. oe
an 25 aoa Pag on fae MINERALOGY > + re “ <e ,
¥ a: ; é - Y os aa :
“2 ¥ n » . iy % Me
B* tm
aoe ments of ane contained i of a “paste of the same “substance i in” 4 Pf ‘
es bia

Sat Se ee as state of decomposition 5, iti is of a very fine. grain, very soft, ~ sf

and almost friable. The other i is “composed of fragments of a F

_ “wacke, | but “more compact, and of globular pieces of basalt. aa “a
=* When these’ ‘globules are ‘broken, the interior is occupied. Oe . €

~ “geodes of crystallised apophyllite, accompanied with capillary. 3

. Inesotype, sometimes decomposed and, reduced to powder, in ea # 3

be Soo * which state it, is known by the nameof Earthy! Zeolite: ‘These™ « 54

:

oe

«p a? %

. are the only minerals. I found in this’ globular’basa It® Thea Apo- a: ir
‘phyllite’ never observed i in the’ other variety of trap- tot, ine’s is? iy
Fg Bt J . which L discovered ‘no simple mineral whatever, except” some»
i Very small geodes of radiated zeolite. IT shall distinguish the nee
St & sf “one by the name of Tr ap-tuff, and the other by that ot Basalt.
tuff. The last appears to me’to be the oldest of the two, and :
We ~occurs, wherever I saw it, under the other. If the tufPbe € én" mS
€ 6. Gal absent, then the Amorphous Basalt occupies _ its place, J
bet 4 2 and on it rests the Amygdaloid the paste of which is of a red- ~~ =e
‘y (. %»° edish-brown colour. It is the amygdaloid. of this colour pk
4°. which the greatest number of minerals o¢cur, such asistilbites ee #:
ae 5 a mesotype, quartz, ¢aleedony, and igloit. When. exposed “to *®
= <=" the action of the weather, this rock becomes extremely deg a
and falls in conchoidal fragments, almost like bole. It occa 4

Pg ~ £% % sionss, particular ly i in spring season, by TEHEON of its “feeble. co
ane hesion, immense deyastation. Rent by the é effects of these- ee
OP a ME vere frosts of winters it falls in huge blocks into. Hbeiral og egal
~ wa" when the basalt, deprived of its support, is Precipitated, Sie
ki . enormous masses} and to such an extent, that rivers.are’ often e
i, .. & impeded in their course, and the whole neighbourhood laid =~
J = under water, « © Over this ‘amygdaloid, a ‘nas’ of 'ferttiginous ea
." ‘ive Hy. lay occurs, ‘similar, to the Eisenthon of the Ger mans, which
2 ae “~. “approaches to the jaspery oxide of iron. This i is again covered
we Tt ee “Sy amorphous” basalt, ‘Separated from columnar ‘basalt, which
AT rg OP SN ae a oe 1 SO é Rss
Se, eg eee ek as, Siete
ai Sec ‘ ¥. “~ ne a Pn: - 9%, sie iy
" a2” Te pes, See Ow ae ~

ao ee wet Bt

s 3s & Rootes Re : ey. 2 a

ive. +
sa' ¥ sh e *
» We ae a Tele | uf %
a
ae

yA

“a ae SF. é tg igh 32 Ha moe a ore roe we peat x
poe.” y-forms. the. suthmits, of “spead*hilly by gndehes, seam of fete #
a> - e same ferruginous substance; 'of a brownish colour. ee rit oe a .
‘hé'mountain c called Ounartorsak, near Godhayn,. presents Pe Pees
“ad he in’ osie of its pigeipices (Sée. Plate: mM. hg Xs:
e. § = ee, . Be aN! > ke _ ie
VP tig-< Set “ae i ee

Basalt, in ae of from three to & exensides ith 6 com ts Engi Sw

Soest f félspar.. ‘og er oa aa sa eg
et ee + rove ea epfaginoié ely. CS. eae
ie oushasalt, with geodes of radiated mene ie >

+

— 4 Agee Ss “ot
7 —— i ah- brown ferniginous clays * < ¥ 2 st rig’
A sng al ce eral ere siite) mesotypes ey.

rs F

me Ateneo oy
Wee ea ae en oer oo ig putas ag
z on vay —y ee te ‘ ie Ay a

vo ew a es
All bi asall of J of ole: is mag ete That | "thd in ew a
mi dei | situations'is rost'805 th e fallen masses dispersed.)
id the base 2 of Pais se having more Hoyas the “ges Ja
i an ; *&
no ntains ivieg Dis ‘0 are wi flat.at the top, att at a z

‘: earance of large houses. It was only in
“thesBay 0” ‘St James, ( , (Omenak’s Fiord), ae oe
ed) ae ‘and conical pusmitogabtanatk, aes .
ae ate XVIL.), is terminated by an im>

l of ne sides... On the summits of all they. cng er 2p

we de ri ie

found numerous rolled masses
a size, and of a weight,
these masses consisted either of »
thor tone.
eo rock among those of the trap-for- ary 2
“Althoug h I ascended several. ofthe. re
vag aye
t al

there it occupied Hy the el
es ee i ihm. tal % Kia

ie re ae “mts = x
By pew re ce be pine, Sy Oy
i ey Eire DISKO ee ibe =e aS 1 B67 ce aes

Unknown Island and Hare 8. ‘* oe

Wie

4,
¢
?
;

35. OP ine a, cm eh: aoe

7 > we ig.

= 268 “ox THE re nea” ‘ta wees
repr © > ‘ 2

to two, atari a clear ringing sound when struck bie: a cf ie ay 3
_ mer. The Gicanlagders informed me, that during tem es-
tuous weather, even at. the foot of the mountain, they es ae

* heard tones resembling those of music;,. and ithat Tornarsuls y: * 2.
» their good and evil ditty, when enraged, was. the cause of them.
~ He never, howeyer, Weer table’ OUle of ‘humour within my
- hearing. . ; ae BOS Sb =, hs ‘ ya
“At the foot of this immense ‘trap: sfortiion of Disko, cont 4, 4

2
derable beds of Sandstone occur. eit makes its appearance ak x:
Aukpadlartok, Akkiarut, and Imnarsoit ; but the~ eAnBSS - of . > : ae 4d
greatest magnitude is at Aumarurtikseet, y where 1 it is accom} dae. ee j
|

nied with beds of Coal. From this spot the beds extend:along* zs 3

~ the edge of the sea, by Waygat, and become very consider- & a
able at Kudliszet, where the stratification i is ; disposed inethe . |
following wifiacinne 2 (ee Re IRS. . Be .
a ¥ . - be 4 + . 45 R %& F :
eaeenncetennentaeeeetes , ’ we i £ % ¥¢ ‘
Sandstone, sometimes with globules of pyrites. te a»
—— 6 “—- & i yp Do Se ed
Brown coal. a oS ew. a Hes
Schistose sandstone. iv em; iit ;
Pitch-coal. aes Pe & 2. aati
—— sd ve F fo y : &
Argillaceous schistus. owe a he
-" Brown coal. _ out ie Waa BS is fe, 5.
qancetane) ava vestiges of pie. ‘ a r * ee
i 2 Me
; > a) wi 4

The lanastde' is very light, : and sometimes friable, which is
also the case with the clay-slate. The vegetable. impressions a
that occur in the lowest bed, seem to be thosetor the leaf of 4"
the Angelica archangelica. The most considerable» bed of 6. )
coal is about 9 feet thick ; while some of the seams are not.

abo! 7 or 8 inches. : pier ee a."
3 ' eae g PF nf elt
, hn a “—- sé
“) ivi
be A
ne ee is Re ‘
\ we? 3 % We

4 Fe ll 4 x P >
im Ae _ ". wy £ e« e 2; ot d = y
¥ phe © = * * a “€ Ze ‘¢ He
¢ » 3 e, +: OF DISKOUSLAND» > “269
o of. Fi Su

Rs
s
BAK

ats is ‘neatly impossible ‘to cts ‘this coal avaliable, as”
shelter is to be found all along the Waygat, for
of any. description, while a tempest almost continually
prev Pn tl Strait. ‘It is the same case with the ¢oal of
33 Tae. Island; generally known on account of the grains of Am-
~ -ber which it contains.” There it occurs” under: an argillaceous
oe in tl Se i dink order : "e

~ Coarse conglomerate. e

Ai htg Niece sy ae
= Agilaccous wacke.

$n coal, with arpa

A _ Fine-grained conglomerate.
5 Sih Sand... sae
i bag aes RY 4
a < sy)" Ea ‘ons cal , ie

to sfhiios the Simple Misc? which ac-
Bh osdie floetz-trap formation of this | country, of. which
ong of the family ¢ of zeolite, its usual com-

‘in Osan of the globe, a the most remarkable.

si
gir

# ; > os ;

ies mie, coca subspecies of this mineral “i

i is ie and radiated. The last is found crystal.
a ot ynied with i. gi

%.

Rene ee
‘fe
2 aie

ee e Z Greenland ths, and hay fond i it to %,
anventirely diffe en a ‘Auvergne | lesotype. In its “erystalline
mit resembles the Aur vergne wedi while, “i in its o eal properties, it re- we
Feeland Mesotypes” It‘is very remarkable, that the capillary crystals ‘ad,
arsoit, have been found by Dr Brewster’ to be different from the
a ad | to be the same as those from Auverens % ts

“e

* . 5 ae a A be S “ithe
aw laces te, Ds:
= pet eine Bh agshecy v
ie we * aft oy
i ae. et F <
it 7 ¥5 a 6
¢ *% sits h We 2
* pt F ~
; ¢
?

int

Ym the

ye.

ws eg

# 4

cs
i 4

- ‘sg ¥ *% 4 : ~ S ‘
ee > - = Ay ag -
¥, et wtb d -¥ ites
a ee skh 4 i: ge as .‘ =
“= 270° » ‘ON THE MINERALOGY,» | % » r
ad * swat

aa” . Be Pg . te x ye 4S ee
ee we B., Capillary. Near Sergyarsoit*in Disko, there is a# ~ #
i se » small cave covered with capillary mesotype, which = =
, ae ' the Greenlanders consider as the hair of one of. a
.& 8 £ their magicians called Angekok. When this val ©.
% riety is decomposed, it forms the earthy or mealy #.
zeolite. * rs
2, Stilbite,—in thin hexagonal tables. ae Te + |
‘ey __ 6. In quadrangular prisms, a truncated .py- et
ramids. ck i :
ai 3. Chabasie,—crystallised in the primitive rhomb. Sy ae
6. In truncated rhombs.»_ 2 |
c. In macles. yy . ie S oS
4. Analcime,—crystallised in the form of the leucite. -s¢,
# 5. Compact Zeolite, white and red.—This mineral occurs»in j
“Ss cavities and veins in all the rocks of the fetz-trap for q
he .mation, except the basalt-tuff. > r Me
; & 6. Ae alte or Ichthyophthalme, 6c RSieiaoes ee car
7 a. In prisms perfectly rectangular. ~ ~ Ped
~ = by b. Also with the solid’ angles replaced. T. is variet.
; was mistaken for mesotype, aud described as Meso-
ee _ type epointé. 3G. au" ok ie
a “ea Bya curious:arrangement of the particles, the ary tals» Se j
- % os of apophyllite are ‘sometimes’ cylindrical, and ng. ,

* =: aa pt: - b Yh | . ys
le ie a ~ contracted at the extremities, -p gsent:theyshape of av + %

; ° w . o 2& . a - ay ze ye: SS ro G
Rh a = a 24 barrel *. They also oceur acuminated and diverging. ,
am 5 Pg’ #9 es : v3 ‘ ~sometimes in the,form of a Tose. In perfect cubes,
iF PH _~ the apophyllite. occurs in, Greenland only in the’ba- ,

oe a ts — - aes - . z . * S. 3 . ih = y

es 3s 3 = salt ae *accompanied ip toliage ed al

grt oa eS is ae ue PY Ree
we i & ES va. od “<' 4 as a>

: ts ‘ is og a : ria i me = , % ’
f ba ys ee te eo ee 2 | a tes a

“27 a e _ * The cylindrical Apophyllite, according to the experiments of Dr BREWSTER, » ws

. % ay *" who has*examined some specimens which I transmitted to him, differs inare- |

ve Ba markable manner from the Apophyllite of Iceland, Faroe, Uto, nd. Passa. * Tes
optical properties he has found to be ofa very curious kind. Fe «
* 38% a Mh WF x “%
% Br he *. ‘a
& tn % “ i : , ke *
wv . : ie + *e a * . rst ;
. * he Ee aici

%
‘+

ISLAND OF DISKO. 271

type. Notwithstanding, in Faroe and Iceland it is
found in wacke. This substance forms an opaque
jelly in nitric acid, frothing up and exfoliating. The
apophyllite also occurs in a radiated form, similar to
stilbite, but with a more brilliant lustre, and pre-
senting on the surface a crystallisation similar to the

th, cock’s-comb barytes.
’ F a :

8. Carbonate of Lime occurs in all the rocks of this formation,
in cavities and veins, of a greyish-white colour, some-
times massive, sometimes crystallised in rhombs, also
: in pyramids of three and six planes, and in prisms of six
| md _ planes, I have found it also crystallised in nearly perfect

4 * ~ “cubes.

#3 a elite the Avogonite of Haiiy, and Hard Calcareous-spar
a "2 of Bournon, occurs fibrous, radiated, and crystallised i in
= * pyramids of three planes ; also in curvilinear prisms of
_ six planes, terminating by degrees in pyramids.

; 10. Radiated and concentric globular mineral, of a yellowish-
green colour, which I take to be Wavellite.
11. Compact Quartz, bacillaire, and crystallised in prisms, in

- geodes. —

Up: Calcedony, massive, and very rarely in cubes. Quartz
and calcedony occur in all the rocks.
13. Opal, common, in veins and cavities, white and yellow,
_ particularly in basalt.
14. Cereolite, a mineral of a yellowish, brownish, and greenish
ia. colour, very similar to compact lithomarge.
is eis. Green Earth, lining cavities, and sometimes filling geodes.
16. Heliotrope, in geodes and veins in basalt.
A: . Agate in geodes i in basalt.
18. Felspar in small crystals, constituting the basaltic-por-

Ea
“A: _ phyry and porphyry-slate.
we vou. IX. P, Il. Mm 19, Fer-
~ % Ea
£ +b
EF 44 “ “

272 ON THE MINERALOGY OF DISKO ISLAND.

19. Ferruginous Clay, of a reddish-brown colour, the Eisen-
thon of Werner. : |

20. Bolus, in small veins.

21. Bituminous Wood, very rately i in minute edey i in wacke
and basalt.

22. Brown-coal...

23. Pitch-coal, above described.

3 a 2

The emicre Rocks, which constitute some em islands on
the south side of Disko, are very rarely accompanied with any
of the simple minerals.. The Felspar of the granite sometimes
becomes opalescent ; the granite contains occasionally com-
pact and prismatic Epidote, also Diallage and Tourmaline; at
Kangek it sometimes, but very rarely, contains some ‘cubes of
Pyrites ; and in one place, I observed Magnetic Iron, i in no-
dules, mixed with it. In the islets of Fortune Bay, I noticed
some specks of the’ green oxide. of Copper in the micaceous
schistus.

XX.

XX. On the Nature and. History of the. Marsh Poison. By
— Wirtiam Fercuson, M. D. F.R.S. E. Inspector of Army-
Hospitals. . .

ie

(Read January 3. and 17, 1820.)

In this paper I propose submitting to the Society some ob-
servations: on the nature and. history of the Marsh Poison,
which, under the title of Marsh Miasmata, or Malaria, has ever
been acknowledged: asthe undisputed source of Intermittent
Fevers, and is believed, with good reason, to be the exciting
cause of the whole tribe of Remittent Fevers ;—of Endemic
Fever, in fact, in every form, and in every part of the world.

All authors who have treated of the nature of this poison,
(and they are most numerous), coincide in attributing its de-
leterious influence ‘to the agency of vegetable or aqueous pu |
trefaction. So universal ‘a coincidence has caused these opi-
nions to be’ received with the authority of an established
ereed. It is my intention in this ‘paper to shew, from a nar-
rative of facts, that they are unfounded, and that putrefaction,
under any sensible or discoverablé form, i is not pleas) to the
production of pestiferous miastata. ne osc os

- The marsh poison, happily so little known in this country,
and fe colder regions of the ‘earth, is notwithstanding by far
“hh Mm 2 the

274 ON THE NATURE AND HISTORY

the most frequent and destructive source of fever to the hu-
man race, as that form of fever to which it gives rise, rages
throughout the world wherever a marshy surface has been ex-
posed for a sufficient length of time to the action of a powerful
sun. I have said for a sufficient length of time; because, as
will presently be seen, the marsh must cease to be a marsh, in
the common acceptation of the word, and the sensible putre-
faction of water and vegetables must alike be impossible, be-
fore its surface can become deleterious. It will also be seen,
that a healthy condition of soil, in these pestiferous regions, is
infallibly regained by the restoration of the marshy surface in
its utmost vigour of vegetable growth and decay. The pre-
vious marshy surface, or rather the previous abundance of wa-
ter, is, however, an indispensable requisite preliminary, in all
situations, to the production and evolvement of the marsh poi-
son. A short review of the circumstances, which, under my
own observation, attended our armies on service during the
last war, will, I hope, render these seemingly paradoxical opi-
nions intelligible to the Society.

The first time that I saw Endemic fever, under the inter-
mittent and remittent forms, become Epidemic in an army,
was in the year 1794, when, after a very hot and dry summer,
our troops, in the month of August, took up the encampments
of Rosendaal and Oosterhout, in South Holland. The soil in
both places was a level plain of sand, with perfectly dry sur-
face, where no vegetation existed, or could exist, but stunted
heath plants: on digging, it was universally found to be per-
colated with water to within a few inches of the surface, which,
so far from being at all putrid, was perfectly potable in all the
wells of the camp. I returned to Holland in the year 1799,

with the army under. the command of the Duke of York,
which

ee

De ey mia

OF THE MARSH POISON. 275

which remained the whole autumnal season in the most pesti-
ferous portion of that unhealthy country, without its suffering
in any remarkable degree from endemic fever. Dysentery
was almost the only serious disease they encountered. Remit-
tent fever was nearly unknown, and intermittent occurred
very rarely; but the preceding summer season had been wet
and cold to an unexampled degree ; during the whole of the
service we had constant rains, and the whole country was one
continuous swamp, being nearly flooded with water. In the
year 1810, a British army at Walcheren, on a soil as similar as
possible, and certainly not more pestiferous, but under the dif-
ferent circumstances of a hot and dry preceding summer, in-
stead of a wet and cold one, suffered from the endemic fever
of the country :to:a degree that was nearly unprecedented in
the annals of warfare.

As I intend, in another part of this paper, to treat fully of
the nature of the localities in the West Indies, I shall pass
over at present my next experience of endemic fever during
three years service in the Island of St Domingo, and proceed
to state what I observed on this. subject in Portugal and
Spain: In the course of the Peninsular War, during the
autumnal campaign of 1808, our troops, after the battle of Vi-
meira, were comparatively healthy. The soil of the province
around Lisbon, where they were quartered, is a very healthy
one, (a slight covering of light sandy soil on a substratum of
hard rock, which is almost always so bare, that water can sel-
dom be absorbed into it to any depth, but is held up to speedy
evaporation). The season was fully as hot a one as is ordina-
rily seen in that country, but dysentery was the prevailing |
disease. Early in 1809 the army advanced to Oporto, for the
expulsion of the French under Marshall Souxr from Portugal
which, during a very cold and wet month of May, (for that

country,)

276 ON THE NATURE AND HISTORY

country,) they effected, without suffering any diseases but the
ordinary ones of the bivouac; and in June advanced again to-
wards Spain in a healthy condition, during very hot weather.
The army was still healthy, certainly without endemic fever,
and marching through a singularly dry rocky country, of con-
siderable elevation, on the confines of Portugal. The weather

had been so hot for several weeks as to dry up the mountain-

streams ; and in some of the hilly rayines, that had lately been
water-courses, several of the regiments took up their bivouac,
for the sake of being near the stagnant pools of water that
were still left amongst the rocks. The Staff Officers, who had
served in the Mediterranean, pointed out the dangerous na-
ture of such an encampment; but as its immediate site,
amongst dry rocks, appeared to be quite unexceptionable,
and the pools of water in the neighbourhood perfectly
pure, it was not changed. Several of the men were seized
with violent remittent fever before they could move from the
bivouac the following morning; and that type of fever, the
first that had been seen on the march, continued to affect that
portion of the troops exclusively for a considerable time. Till
then it had always been believed amongst us, that vegetable
putrefaction (the humid decay of vegetables), was essential to
the production of pestiferous miasmata; but, in the instance
of the half-dried ravine before us, from the stoney bed of
which, (as soil never could lie for the torrents,) the very exist-
ence even of vegetation was impossible ; it proved as pestife-
rous as the bed of a fen. The army advanced to Talavera
through a very dry country, and in the hottest weather fought
that celebrated battle, which was followed by a retreat into the
plains of Estremadura, along the course of the Guadiana river,
at a time when the country:was. so arid and dry, for want of
rain, that the Guadiana itself, and all the smaller streams, had

in

~~ ~~

;
4
:

OF THE MARSH POISON.) © g17

in fact ceased to be stredms, and were no more than lines of de-
tached pools in the courses that had formerly beén rivers; and
there they suffered from remittent fevers of such destructive
malignity, that the enemy, and all Europe believed, that the
British host was extirpated; atid the superstitious natives,
though sickly themselves, unable to account for disease of such
uncommon type amongst. ‘the strangers, declared they had all
been poisoned by eating the mushrooms, (a species of food they
hold in abhorrence,) which sprung up after the first autumnal
rains, about the time the epidemic had attained its height.
The aggravated cases of the disease differed little or nothing
from the worst yellow fevers of the West Indies; and in all
the subsequent campaigns of the Peninsula, the same results
uniformly followed, whenever, during the hot seasons, any
portion of the army was obliged to occupy the arid encamp-
ments of the level country, which at all other times were heal-
thy, or at least. unproductive: of endemic fever.

To save further narrative, I shall finish this part of the sub-
ject, by ete some gid elation illustrations.

The bate hilly country near Lisbon, where the foundation
of the soil, and of the beds of the streams is rock, with free open
water-courses amongst the hills, as I have said before, is a very
healthy one; but the Alentejo land, on the other side of the
Tagus, ehoush as dry superficially, being perfectly flat and
sandy, is as much the reverse as it is possible to conceive.
The breadth of the river, which at Lisbon does not exceed two
miles, is all that separates the healthy from the unhealthy re-
gion ; and the villages or hamlets that have been placed along
the southern bank of the Tagus, for the sake of the navigation,
are most pestiferous abodes. The sickly track, however, is
not confined to’ the immediate shore of the river. Salvaterra,

for

278 ON THE NATURE AND HISTORY

for example, about a mile inland, is a large village, and royal
hunting residence in the Alentejo, which is always reputed to
be very healthy till the beginning of the autumnal season,
when every person, who has the means of making his escape,
flies the place. In their superstitious fear, the inhabitants de-
clare, that even the horses and other animals would be seized
with fever if left behind, and therefore they always remove the
royal stud. The country around is perfectly open, though
very low, and flooded with water during the whole of the rainy
season ; but at the time of the periodical sickness it is always
most distressingly dry ; and exactly in proportion to the pre-
vious drought, and consequent dryness of soil, is the quantum
of sickness. I have visited it upon these occasions, and found
it the most parched spot I ever saw. The houses of the mi-
serable people that were left behind being literally buried in
loose dry sand, that obstructed the doors and windows.
Cividad Rodrigo affords another illustration of the same. It
is situated on a rocky bank of the river Agueda, a remarkably
clear stream ; but the approach to it on the side of Portugal is
through a bare open hollow country, that has been likened to
the dried up bed of an extensive lake; and upon more than
one occasion, when this low land, after having been flooded in
the rainy season, had become as dry as a brick-ground, with
the vegetation utterly burned up, there arose fevers to our
troops, which for malignity of type could only be matched by
those before mentioned on the Guadiana.

At the town of Corea, in Spanish Estremadura, not very
dissimilarly situated, on the banks of the Alagon (also a very
pure and limpid stream,) our troops experienced similar re-
sults; with this addition clearly demonstrated, that no spot of
the pestiferous savannah below the town, was so much to be
dreaded as the immediate shores of the river ; so that even the

running

ee

OF THE MARSH POISON. 279

running stream itself, which in all other countries has been

esteemed a source of health, and delight and utility, in these
malarious lands proved only an addition to the endemic pesti-
lence. It is difficult to conceive any thing more deceptious
than the appearance of these two towns, eh EE the last,

which might have been pitched upon by the best instructed
medical officer, if unacquainted with the nature of Malaria, as
a place of refuge from disease ; for the shores of the river, (it
had no confining banks,) seemed perfectly dry, and there was
not an aquatic weed, nor a speck, nor line of marsh, to be seen
within miles of the town, nor any thing but dry, bare, and
clean savannah. It had, however, been so far the contrary in
all past times, that the canons and ecclesiastics of its ancient
cathedral had a dispensation from the Pope, of no less than
five months leave of absence, to avoid the Calentura, (their
name for the endemic fever). In the other ecclesiastical resi-
dences of Estremadura, the same dispensation rarely extended
beyond ¢hree months, but almost all had some indulgence of
the kind. During the autumnal season, the epidemic prevail-
ed so generally amongst all classes of inhabitants, that even
infants at the breast were affected with it, and few of the resi-
dents attained to any thing like old age. The oldest person I
ever saw in Corea, who was a priest, that had often taken ad-
vantage of. the dispensation for leave of absence, was only in
his 57th year, and he appeared like a man past 70. The inha-
bitants, nevertheless, seemed always surprised and offended
when we ‘condoled with them on the unhealthiness of their
country, which they would not admit in any degree; for with

them, as every where else, where immemorial experience has

shewn that it is impossible to avoid a calamity, it goes for no-
thing. They contemplated its approach with the same indif-
ference t that a Turk does the plague, and patiently awaited its

VOL.IX. PIL. | wn extinction

280 ON THE NATURE AND HISTORY

extinction by the periodical rains of the winter season, not,

however, without some exultation, and self-congratulation, on
the greater comparative mortality that occurred amongst the
stranger soldiers than amongst themselves.

From all the foregoing, it will be seen, that in the most un-
healthy parts of Spain, we may in vain, towards the close of
the summer, look for lakes, marshes, ditches, pools, or even ve-
getation. Spain, generally speaking, is then, though as prolific
of endemic fever as Walcheren, beyond all doubt one of the
driest countries in Europe, and it is not till it has again been
made one of the wettest, by the periodical rains, with its ve-
getation and aquatic weeds restored, that it can be called heal-
thy, or even habitable, with any degree of safety.

—=>—

During the years 1815, 1816, and 1817, I was employed in |

making a topographical health survey of all the West India
colonies, which afforded me opportunities, in that diversified,
dangerous, and active climate, of improving the observations I
had elsewhere made upon pestiferous miasmata, of a kind that
I could scarcely have anticipated.

It might there be seen, that the same rains which made a
deep marshy country perfectly healthy, by deluging a dry well
cleared one, where there was any considerable depth of soil,
speedily converted it, under the drying process of a vertical
sun, into a hot-bed of pestiferous miasmata. Thus, in the
Island of St Lucia, the most unwholesome town of Cas-
tries, at the bottom of the Carenage, which is altogether em-
bosomed in a deep mangrove fen, became perfectly healthy

under the periodical rains ; while the garrison, on the Hill of

Morne Fortuné, immediately above it, within half cannon shot,
began to be affected with remittent fevers. The two localities
within this short distance evidently changed places in respect

to

a a

OF THE MARSH POISON. 281

to health. The top and shoulders of the hill had been cleared

of wood, and during a continuance of dry weather, the garri-
son had no source of disease within itself, but this was amply,
though but temporarily supplied, as soon as the rains had sa-
turated the soil on which it stood. Thus an uncommonly
rainy season at Barbadoes, seldom failed in that perfectly dry
and well-cleared country, to induce for a time general sick-
ness; while at Trinidad,—which is almost all swampy, and the
centre of the island may be called a sea of swamp, where it
always rains at least nine months in the year,—if it only rain-
ed eight, or if at any time there was a cessation of the preser-
ving rains, the worst kind of remittent fevers were sure to
make their appearance. General dryness of soil, however, is
far from being the ordinary characteristic of our West India
colonies. The swamp is too often exposed to the continued
operation of a tropical sun, and its approach to dryness is the
harbinger of disease and death to the inhabitants in its vicini-
ty. On the whole, it may truly be said, that although exces-
sive rains will evidently cause the acknowledged wholesome
and unwholesome soils to change places for a time, in respect
to health, a year of stunted vegetation, through dry seasons,
and uncommon drought, is infallibly a year of pestilence to the
greater part of the West India colonies.

In some other respects, the history of Miasmata in these
countries was curious and interesting. Thus at the town of
Point au Pitre, Guadaloupe, which is situated amidst some of
the most putrid marshes in the world, the stench of which is
almost never absent from the streets, the place was far from

being uniformly unhealthy. Strangers, however much they

might be annoyed with the smell, often resorted to it with im-
punity. No more was its first out-post fort Louis, where the
waters are so stagnant and putrid, that it is even more offen-

nn 2 _ sive

282 ON THE ORIGIN AND HISTORY

sive than Point au Pitre; but at Fort Fleur d’Epeé, the far-
thest out-post, at the extremity of the marshes, where they
approach to the state of Terra Firma, where little or no water
is to be seen on the surface, and no smell exists, there cannot
be supposed a more deadly quarter, and all white troops con-
sidered their being sent there, as equivalent to a sentence of
death, It ought to be noted, that the marshes of all these
three posts are overgrown with the thickest underwoods, and
rankest aquatic vegetation of every kind. A fact of the same
kind has been observed in the Island of Tobago. The princi-
pal fort and barrack of the colony, has been placed immediate-
ly to leeward of the Bacolette swamp, within the distance of
less than half a mile, and the strong ammoniacal stench of
its exhalations, even at that distance, often pollutes the
barracks; but these are so far from producing fever at all
times, that when I visited the white garrison there, they had
been more remarkably exempt from that form of disease, for
several years, than any other troops in the West Indies. I
shall not multiply facts and illustrations of the same kind, to
prove that putrefaction, and the matter of disease, are altoge-
ther distinct and independent elements; that the one tra-
vels beyond the other, without producing the smallest bad ef-
fect ; and that, however frequently they may be found in com-
pany, they have no necessary connection ; but proceed to no-
tice other qualities of the marsh poison, which, until oe
stood, prove extremely puzzling to the observer.

In selecting situations for posts and barracks, it had been
observed with surprise, that the border, and even the centre
of the marsh, proved a less dangerous quarter than the neigh-
bouring heights of the purest soil; and healthiest temperature ;

and

OF THE MARSH POISON. 283

and this has never been more strongly a aed than i in the

‘instances Tam a is to Pia 2 |

T fh

Port of Spain, Trinidad, this opal of the island: is J Stoeted
very near the great eastern marsh, with which it is in direct
. communication, by a marginal line of swamp along the sea-
! shore. It cannot be called a healthy town, but it is very far
. from being uninhabitable. On the right are some govering
‘heights, which rise out of the marsh at one extremity. These,
unlike the site of the town, which has been built on marshy or
alluvial ground, are composed of the driest and most healthy
materials,—(pure limestone, the purest and the best in all the
West: Indies), yet have they proved a residence deadly and de-
‘structive in the greatest degree to all who venture to inhabit
‘any part of: their diversified surface. No place, however eleva-
ted, or sunk, or ‘sheltered, or walled in, gives security against
‘the exhalations from below, only it Ros been distinctly ascer-
‘tained, that these prevail with more or: less malignity, exactly
‘in ‘proportion to the elevation of the dwelling. The lower,
"consequently the’ nearer the marsh, the better. The tops of
the ridges are ‘uninhabitable. On the highest top, at an ele-
vation of 400. feet, and farther removed from the marsh than
the town itself, a Jarge martello tower was built to defend the
place. It possessed a fine temperature, but proved so dan-
gerous a quarter, that it was obliged to be abandoned. Not
even a ‘creole mulatto Spaniard could sleep in it with impuni-
ty fora single night, ‘after a course of dry weather.

The beautiful post of Prince Rupert’s, in the Island of Do-
minica, is a peninsula which comprehends two hills of a re-
_markable form, joined to the main land by a flat, and very
marshy square 1 isthmus to windward, of about three quarters

284 ON THE ORIGIN AND HISTORY

of a mile in extent *. The two hills jut right out on the same
line into the sea, by which they are on three sides encompas-
sed. The inner hill, of a slender pyramidal form, rises from a
narrow base nearly perpendicular, above and across the marsh,
from sea to sea, to the height of 400 feet, so as completely to
shut it out from the post. The outer hill is a round-backed
bluff promontory, which breaks off abruptly, in the manner of
a precipice, above the sea. Between the two hills runs a very
narrow clean valley, where all the establishments of the garri-
son were originally placed ; the whole space within the penin-
sula being the driest, the cleanest, and the healthiest surface
conceivable. It was speedily found that the barracks in the
valley were very unhealthy, and to remedy this fault, advan-
tage was taken of a recess or platform near the top of the in-
ner hill, to construct a barrack, which was completely conceal-
ed by the crest of the hill from the view of the marsh on the
outside, and at least 300 feet above it; but it proved to be pes-
tiferous beyond belief, and infinitely more dangerous than the
quarters in the valley, within half musket-shot below. In fact
no white man could possibly live there, and it was obliged to
be abandoned. At the time this was going on, it was disco-
vered, that a quarter which had been built on the outer hill,
on nearly the same line of elevation, and exactly 500 yards
further removed from the swamp, was perfectly healthy, not a
single case of fever having occurred on it from the time it was
built. These facts were so curious, that I procured the Sur-
veyor-General of the island to measure the elevations and dis-
tances, and I have given them here from his report.

In

* The superficies of the base of the peninsula is exactly 1210 yards in length,
by 850 in breadth, exclusive of the isthmus.

S «Det< —_ ~
So Pete loan —

OF THE MARSH POISON, 285

In the Island of Antigua, the same résults were confirmed
in a very striking manner. The autumn of 1816 became very
sickly, and yellow fever broke out in all its low marshy quar-
ters, while the milder remittent pervaded the island generally.
The British garrison of English Harbour soon felt the influ-
ence of that most unwholesome place. They were distributed
on a range of fortified hills that surround the dock-yard. The

principal of these, Monks Hill, at the bottom of the bay, rises

perpendicular above the marshes to the height of 600 feet..
The other garrisoned hill, which goes by the name of the
Ridge, is about 100 feet lower, but instead of rising perpendi-
cularly, it slopes backwards from the swamps of English Har-
bour. It was the duty of the white troops, in both these forts,
to take the guards and duties of the dock-yard amongst the-
marshes below, and so pestiferous was their atmosphere, that
it often occurred to a well-seasoned soldier mounting the
night-guard in perfect health, to be seized with furious deli,
rium while standing sentry, and when carried back to his bar-
racks on Monks Hill, to expire in all the horrors of the black
vomit, within less than 30 hours from the first attack ; but du-
ring all this, not a single case of yellow fever, nor fever of any.
kind, occurred to the inhabitants of Monks Hill; that is to say,
the garrison staff, the superior officers, the women, the drum-
mers, &c., all in fact that were not obliged to sleep out of the
garrison, or take the duties below, remained in perfect health.
The result on the Ridge was not quite the same, but it was
equally curious and instructive. The artillery soldiers, (17 in
number) never took any of the night guards, but they occupied’
a barrack about 300 feet above the marshes, not perpendicular
above them, like Monks Hill, but a little retired. Nota case
of yellow fever or black vomit occurred amongst them, but
every man, without a single exception, suffered an. attack of

riod ® j ; the

286 ON THE NATURE AND HISTORY

the ordinary remittent, of which one of them died ; and at the
barrack on the top of the Ridge, at the height of 500 feet, and
still further retired from the marshes, there scarcely occur-
red any fever worthy of notice.

Another property of the marsh poison, is its attraction for,
or rather its adherence to, lofty umbrageous trees. This is so
much the case, that it can with difficulty be separated from
them ; and in the territory of Guiana particularly, where these
trees abound, it is wonderful to see how near ¢o leeward of the
most pestiferous marshes the settlers, provided they have this
security, will venture, and that with impunity, to place their
habitations.

The localities of the plantations situated on the windward

banks of the rivers that intersect Guiana, and are generally co-
vered by swampy woods in close vicinity, exemplify this fact
in a remarkable manner ; and at Paramaribo, the capital of Su-
rinam, the trade-wind that regularly ventilates the town, and

renders it habitable, blows over a considerable tract of swamp:

at a short distance, but which, fortunately for the inhabitants,
is thickly covered with umbrageous forests. Experience, be-
sides, has shown, that there, as in all other new lands, the cut-
ting down of those trees in the:swamps has ever been a fatal
operation in itself, and in all selena mouis be productive
of pestilence to the town *. .

It would be trespassing wantonly on the. time and satience
of the Society, to multiply further observations of the same

_ kind,

* The town of New Amsterdam, Berbice, is situated within; short musket-shot
to leeward of a most offensive swamp, in the direct track ofa strong trade-wind,
that blows night and day, and frequently pollutes ¢ even the sleeping apartments of
the inhabitants, with the stench of the marshes, yet it had produced no endemie
fever worthy of notice, even amongst the newly arrived, for a period of months
and years previously to my visiting that colony.

ee

v 1COF THE MARSH!POISON, > 287

kind, \and'I-shall therefore proceed’ to draw some conclusions,
which I think are fairly dorado i facts and: narrative
f ii submitted.’ de : noelk as, dd dads (bise <
Val trovorgeiy ad Yat aids Adis DL jonols mork WEG CHK
9 That! the’ tthe iach erfianate froth sear pu-
Serstaatidnt? P think must°be" evident ‘from the fact, that it is
found miost virulent atid”abundant'on the | driést surfaces }of-
ten where vegetation ever existed, Or could exist ‘for 'the:tor-
rents, ‘stich’ the ‘deép and” *stéép tay ihe of a dried water-
‘dotitsé; and’ that it'isctéver found’ “in savannahs or plains, that
thavel ell Alsotedl ii che rainy season, ti ‘their ‘surface has
‘been thoroughly exsiccated ; Ve étation’ burnt up - and its pu-
eferueiol renders ad nip? ‘a8 ‘the’ ssluaebesTot of an
-Egyptian’ mummy. If this*be doubted ‘or deiiied, let us'take
‘examples'whetévédetablé puttefaction'is: sélPevident, and éxa-
imine whether it’be productive of’ disease and déath, similar to
(what emanates? frony thé" marsh. poison. Surély the evidence
of every ‘dung’ heap, ‘iit every’ part of the world, will answer
‘the'question ain the negative; or ‘if it be insisted: that the poi-
-8on jis) generated from a‘combination “of aquedus- ‘and: vegetable
‘putrefaetion, ‘let us resort to\the easy familiar illustration of a
West India sugar-ship, where the arainings « of the stigar, mix-
-ing with the bilge-water' of the ‘hold, creates a stench that is
-absolutely suffocating to those unaccustomed to it; yet fevers

_are ni aoe known to be Learners from. such. a dcaaaation.

doese

' Se. hes f teatiape! to be sure, have: ates to) ordonan-

ces against. the steeping of hemp: in stagnant pools, but these
-resemble many other ordonances relative to health everywhere ;
in “overlooking the leading | primary causes of the stagnant
‘pool, ‘the. autumnal, season, and the malarious lands. around,

VOL. IX. P. II. 00 and

288 ON THE NATURE AND HISTORY

and having their point directed to.a sti ‘concomitant cir-
cumstance of no importance.
Should it be said, that the poison must then emanate from
aqueous putrefaction alone, I think this may be disproven by
equally familiar examples,, The bilge-water in the holds of
ships, which at all times smells more offensively. than the most

acknowledged. pestiferous marshes, would in that case infalli--

bly, and at all times, be generating fevers amongst the crew,
more particularly in tropical climates, : 1 need scarcely say,
that this does not consist ;with the. fact, unless it be in some
rare instances, where the bilge-water has become, like that of
the marsh, actually dried. up, or absorbed into the collected
rubbish and foulness of the ship’s well, thereby verifying the
common saying of the sailors, that.a leaky ship is-ever a heal-
thy ship, and vice versa. Or if it. be objected, that the salt
may have a preserving power, let us look at the quantity of
fresh-water, (not unfrequently the impure water of an alluvial
river), laid in for a first-rate man of war proceeding on a long
voyage. This is so great as to.constitute many floorings, or
tiers of barrels, close to. which the-people sleep with impunity,
though it is always disgustingly putrid, and could not fail to
affect them, if it contained any seeds of disease *, Examples of
the same on land may be found with equal facility. At Lis-
bon,

Jt

* In some ships of our navy, the fresh-water, instead of being-put up in casks,

has been preserved in bulk, by constructing a large open tank, of tin or lead, at «

the bottom of the hold, without in the least affecting the health of the crew,
though they slept immediately above it. On land, the very same results have
been verified under the same circumstances. One of the healthiest officers’~quar-
ters in the West Indies, is the field-officers at Berkshire Hill, St Vincent's, which
is built immediately over the garrison water-tank; and a block house at Deme~
‘rara, similarly situated, was healthier than the other posts on terra firma. —

OF THE:;MARSH POISON. 289

bon, and throughout | Portugal, there) can be no gardens, with-
out water; but the garden is almost every thing to a Portu-
guese family. All classes of the inhabitants endeavour to esta-
blish and. preserve them, particularly in Lisbon, for which pur-
_pose they have very:large stone! /reservoirs: of water; that-are
filled by pipes from) the: public aqueducts, when water:is abun-
dant ;—but these supplies are.always cut off in, the summer
The water, consequently, | being .most precious, is husbanded
with the’ utmost care, for'the three: months. absolute drought of
the summer-sedson, » jdt falls, alts course into the most concen-
trated state of foulness ;and’ ‘putridity, diminishing and evapo-
rating day after day, but never absorbed, , till it; subsides either
into a thick green, vegetable scum, Or a, dried. crust., .In-the
confined gardens of, Aisbon, particularly, these. reservoirs may
be seen. in this. statejclose » to, the ,houses, even, to. the. sleeping
places of the household, 3 dn. the, atmosphere of which they lite-
rally live and breathe,;, yet, no, one ever heard or dreamt of fe-
ver being generated amongst; them, from such a, source ; though
the most ignorant, native;,is .well) aware, that were he, ‘only to.
cross the rivér, and sleep-on, ‘the sandy shores of the. Alentejo,
where a particle of water at that season. had not.been seen for
months, and where water being absorbed into the sand as soon
as it fell, was never known, to be putrid, he. would run the
greatest risk of being seized. with remittent fever. ,
_ From all the foregoing, the deduction appears to be unque-
stionable, that endemic fevers cannot be generated either from
aqueous or vegetable putrefaction, singly or. combined., It ema-
nates, as we have seen, from the shores of the purest: streams,
wherever they have been flooded during the rains, through.
want of confining’ banks, and it-is absent from the most putrid
waters.: It must ‘be <iigtohige that healthy living: ae which
“eit Yin Budo 23 Li otf Qoyo orfi oF sOqGRel from

290 ON THE ORIGIN AND HISTORY

from its current is in a perpetual course of being refreshed and
renewed, can ever, by any degree of'solar heat, be brought into
the state of morbific miasmata; and*the evil must therefore
reside in the half-dried and drying: margin ; for the swamp is
no more than this margin rolled up under another shape, and
it must be brought into the same-degree of dryness, asin it
can produce any morbific effects.o18 © ««)' — ’
One only condition then ‘seems: ‘to be: indlispenaabhes to: 1Ke
production of the marsh poison, on all surfaces capable of ab-
sorption ; and that is, the°paucity of water, where it has pre-
viously and recently abounded. To this there is no exception
in climates of high temperature ; ; and from thence we may just-
ly infer, that the poison is produced at a highly advanced stage
of the drying process ;—but, in the preseht ‘state of our know-
ledge, -we'can no more tell what’ that precisé stage may be, or
what that poison acttially “is;' the development ‘of ‘which ‘must
necessarily be ever'varyingy according to:circumstances of tem=
perature, moisture, elevation, perflation; aspect, ‘texture, and
depth of soil, thaa-we an’ define ‘and describe‘those vapours
that generate typhus fevers, stmallpox;' and ‘other! diseases.
The marsh and the stagnant pool will no doubt be pointed out
as the ostensible sources: from: which’ thispoison ‘has ever
sprung; but the marsh, it has been’seen, is never pestiferous.
when fully covered with water: ” At all other times: it must
present ‘a great) variety of drying ‘surface, and botl the lake
and the marsh must’ ever possess: their saturated, half-dried;
and drying margins. It is from these’ that’ the poison: uni-
formly emanates, and never from’ the body of the lake or pool,
and I think it: may even be fairly presumed that water, for as
long as it can preserve ‘the figure of its. particles: above the sur-
face, is innoxious, and’ that -it- must first be absorbed into the
soil, and disappear to the eye, before it can produce any mis-
chievous,

aquatic weeds ' that ‘cove

OF THE MARSH POISON, 291

ehievous effects... The most ignorant peasant of Lincolnshire
knows, that there is: nothing: to. be apprehended from the
ditches of his: farm till they have‘been dried up bythe summer
heat; and though the inhabitant of Holland:may point to the
unexhausted foul canal as the source of his autumnal fever,
there can ‘be little doubt that he might live upon‘a sea. of the
same with impunity, and that itis to'the absorbed waters un-
der his feet, which, without the ‘canal, would in all probability
be much more pestilential, he ought: to attribute his disease.
To assert, after all this, that the putrid marsh, which must ne-
cessarily, to a‘ certain’ degree, ‘be @ wet'one, is positively less
dangerous than another where no smell exists, will not, I am
sure, appear, paradoxical to the Society; for it is only saying,
thatthe first has! not: yet arrived ‘at: the degree of exsiccation
that‘has been found most productive of the marsh poison, and’
that putrefaction, though it may; ‘and must often precede and
aucompgny pestilence, is no part-of pestilence itself.

The: apnibol of vegetable putrefactiony in the decay of the
ver the pool,’ constantly meets the eye,
and deceives’ he judgment and» ‘the: smell of the putrefying
waters combined with it, confirms a delusion which has ever
prevented us from discovering, that the action ofa powerful
sun on its halfdried margin, ‘is adequate to the production of
all'that' coald'be attributed to the humid decay of’ vegetables.
The greatest: danger then may, and does often exist, where no
warning’ whatever’ is perceptible to the senses, and whoever,
in malarious countriés, waits for the evidence of putrefaction,
will, in all the most dangerous places, wait too long, as every
one ¢an testify’ who has seén pestilence steam forth, ‘to the pa-
ralyzation of. “armies, ‘from the bare barren sands of ‘the Alen-
tejo in- ‘Portugal, the ‘arid burnt plains of Estremadura’ in
panic —and the recently flooded table-lands of Barbadoes, which

have

2}

292 ON THE ORIGIN AND HISTORY

have seldom more than a foot of soil to cover the coral rock,
and are therefore under the drying process of a tropical sun,
brought almost immediately after the rains into a state to give
out pestilential miasmata.

I shall conclude this paper with a few more observations on
some of the qualities not yet noticed of the marsh poison.
No experiments hitherto made have enabled us to pronounce
whether it be specifically heavier or lighter than common air ;
but it evidently possesses an uncommon and singular attrac-
tion for the earth’s surface; for in all malarious seasons and
countries, the inhabitants of ground floors are uniformly affect-
ed in a greater proportion than those of the upper storeys.
According to official returns during the last sickly season at
Barbadoes, the proportion of those taken ill with-fever, in the

lower apartments of the barracks, exceeded that of the upper |

by one-third, throughout the whole course of the epidemic.
At the same time it was observed, that the deep ditches of the
forts, even though they contained no water, and still more the
deep ravines of rivers and water-courses, abounded with the
malarious poison. At Basseterre, Guadaloupe, a guard-house
placed at the conflux of the inner and outer ditch of the fort,
infallibly affected every white man with fever that took a
single night-guard in it ; and the houses that were built in the
ravine of the river aux herbes, (a clear rapid mountain-stream
that runs through the town) or opposite to its “ bouchure,”
proved nearly as unhealthy as the guard-house above men-
tioned.

Another proof, that from the attraction above mentioned it
creeps along the ground, so as to concentrate and collect on
the sides of the adjacent hills, instead of floating directly up-
wards in the atmosphere, is the remarkable fact, that it is cer-

tainly

a eee

OF THE MARSH POISON: 293

tainly lost and absorbed by passing over a small surface of wa=
ter ; which could scarcely happen, unless it came into direct
contact with the absorbing: fluid. The rarefying heat of the
sun, too, certainly dispels it, and it is only during the cooler
temperature of the night that it acquires body, concentration,
and power. All regular-currents/of wind’ have also the same
effect, and I conceive it to be through the agency of the trade
wind: alone, which blows ‘almost constantly fromy east to west, .
that the greater part of the West Indies is rendered habitable.
When this purifying influence is withheld, either through the
circumstances of season, or when it cannot be made to sweep
the land on account of the intervention of high hills, the con-
sequences are most fatal.. The leeward- shore of Guadaloupe;
for a course of nearly thirty miles, under the shelter of a very
shigh steep ridge of volcanic mountains, never felt the sea-
breeze, nor arly breeze but the night: land-wind from the moun-
tains; and though the soil, which I have often examined, is a
remarkably open, dry, and. pure one, being mostly sand and.
gravel, altogether: and. positively without marsh in the most
dangerous places, it is inconceivably pestiferous throughout
the whole tract, and in no spot more so than the bare sandy ~
beach near the high water-mark*. © The coloured people
ngod Bath, tyzot | gist alone

mise , ag i

id Tn our own country, an instance of a pure surface, ‘absolutely destitute of
vegetation, proving as malarious as any other’spot that I know of in England, may
“be seen at Dungeness, on the coast of Kent. The point of Dungeness, is a tongue
of land appended) to.the. great Romney Marsh, and consists of an extensive bank
of shingle or gravel, so dry; loose, and open. that even during wet weather horses
sink in it nearly up to the knees. ‘The forts and barracks are at least four miles
from what may be called the Mainland, where the grass begins to grow, yet was
there no spot of, that unwholesome tract of country more prolific of endemic fever
during the hot summer and autumn of 1807 than these barracks. In one part of
the gravel, but not near the barracks, were some very deep pools, of no great ex-
tent, containing a singularly pure pellucid fresh-water.

294 ON THE ORIGIN AND HISTORY

alone ever venture to inhabit it, and when they-see strangers
tarrying on the shore after night-fall, they never fail to warn
them of their danger. The same remark holds good in regard
to the greater part of the leeward coast of Martinique, or the
leeward alluvial basis of hills, in whatever-part of the. torrid
zone they maybe placed, with the exception probably of the
immediate sites of towns, where the pavements prevent the
rain-water being absorbed into the soil, hold it up to
speedy evaporation. ne

For this; if there be a remedy, ‘it. Aniiell ane Govriodt 3 in the
powers of cultivation, ever opening the surface for the escape
of pestilential gases, and exhausting the morbific principle by
a constant succession of crops ; for wherever malaria prevails,
the uncultivated savannah, even though used:for pasture, be-

comes infinitely more pestiferous than. the plantation, and the*

depopulated: country falls completely under ‘its dominion.
With the aid) of the purifying sea-breeze, ‘this ‘course at the
British:colony of Demerara, within six degrees ofthe equator,
has succeeded in rendering the cultivated portion of the deepest
and most’ extensive: morass: probably in the world, a ‘healthy,
fertile, and beautiful settlement. : I shall not here ‘enter into a
detailed account of the astonishing ‘system of ‘tide and flood-
gate drainage by which this delightful result has been esta-
blished and kept up, but hasten to a conclusion, ___

It would be unphilosophical to suppose, that the marsh poi-
son, because other distempers, such as dysentery, co-exist with
it, ever produces any disease but the specific one of which it is
the acknowledged parent, varying, however, in form, and as a
modification of effect from the same cause, from the common
ague of the fens of Lincolnshire, through all the milder remit-
tent types, up to the aggravated yellow fever, or malignant re-
mittent of the West Indies; and that variation, so certain and

uniform,

TY enets ste

5 aii tia alll

OF THE MARSH POISON.’ 295

uniform, in proportion to the power of the remote exciting
cause, that the varying types of fever might be measured al-
most to a certainty by the degrees of solar heat, as marked on
the thermometer. Thus it is most rare and uncommon to
meet with an ague in the West Indies in the swampy alluvial
plains at the level of the sea, where the generality of the towns
and settlements are placed ;—as rare, or rather as impossible,
as it would be to meet with any thing else but a common re-
mittent or an intermittent fever, on the cooler mountain mar-
shy levels of the same country. The highest degree of suscep-
tibility and excitement from solar heat on the part of the sub-
ject, combined with the highest state of preparation from the
same, on the part of the agent, appear to be essential in all si-
tuations to the production of the dreadful yellow fever, which,
luckily for mankind, is incapable of being transported to any
locality of lower temperature, or texture of soil different from
that which gave it birth. Need I say, that such a disease,
however rapid and appalling may be its epidemic current, is
not, and cannot, no more than the common ague or remittent
fever, be in the smallest degree contagious.

There are very few, indeed, of those that have been compel-
led to live under its scourge, who have not overcome the pre-
judices of their education on this head; but, unluckily, a dif-
ferent impression obtains very generally amongst those who
have never seen the disease, which deeply affects the peace of
society every where, and in some countries has proved subver-
sive of the best interests of humanity. Such opinions, it is the
duty of every man, who has had sufficient experience, to com-
bat, by stating the results of personal exposure and investiga-
tion, and thereby do his utmost to rescue medical science
from the dominion of a prejudice which disgraces it.

VOL. IX. P. II. Pp LF

296 ON THE ORIGIN AND HISTORY

I shall now close this tedious paper, wherein | have endea-
voured, as much as possible, to avoid all professional disquisi-
tions, or references to authors, or even allusion to any ground
on which I have not personally trod. It was my earnest wish
to have made it shorter; but amidst the multiplicity of matter
and illustration, with which I have been literally oppressed, I
found that I could not abridge it farther, and at the same time
do justice to the subject.

NOTE,

OF THE MARSH POISON. 297

NOTE.

ON THE NEGRO SKIN.

THE adaptation of the Negro to live in the unwholesome localities of
the Torrid Zone, that prove so fatal to Europeans, is most happy and
singular. From peculiarity of idiosyncrasy, he appears to be proof against
endemic fevers; for to him marsh miasmata are in fact no poison, and
hence his incalculable value as a soldier, for field service, in the West In-
dies. The warm, moist, low and leeward situations, where these perni-
cious exhalations are generated and concentrated, prove to him congenial
in every respect. He delights in them, for he there enjoys life and health,
as much as his feelings are abhorrent to the currents of wind that sweep
the mountain tops, where alone the whites find security against endemic
fevers.

One of the most obvious peculiarities of the Negro, compared with the
European, is the texture of his skin, which is thick, oily and rank to a
great degree : and from this circumstance the theorist, when he speculates
on the mode of reception of the marsh poison into the constitution, whe-
ther by the lungs, the stomach, or the skin, may draw a plausible conjec-
tural inference (for it can be no more) in favour of the last. It is cer-
tain, that amongst Europeans, the thick-skinned and dark-haired with-
_ stand the influence of the marsh poison much better than those of the op-
posite temperament; and it is equally certain, from the never-failing pri-
mary head-ache, that its first impression is invariably upon the brain, as
if it had been taken up by the sentient extremities of nerves, of which
the skin is so truly an expansion, and conveyed to the sensorium.

Another argument of analogy, in favour of the same opinion, may be
derived from a reference to the plague, which is the pestilential endemic
fever of the Levant, or rather of the arid sandy regions of the southern

Pp 2 coasts

298 1 NOTE.

coasts of the Mediterranean. In that disease, we see reason to believe,
that the poison enters by the skin, because swellings of the lymphatic
glands are amongst its most prominent “symptoms; because oily frictions
on the skin are said to be preservative against it, and that carriers or
workers in oil do not take the disease.

When the poison is received into the constitution, through whatever
channel it may enter, its effects are actually not very dissimilar in some
cases to those from the bite of’ a serpent. The aggravated cases of yel-
low fever at Antigua, mentioned in this paper, and those that have fre-
quently occurred at St Lucia and Martinique, from the bite of the large
brown viper of these islands, ran a course not without some resemblance,
in the impaired nervous energy, the vomitings, and dissolution of the
blood, as marked by the livid discolorations under the skin, (hence the
very improper name of Yellow Fever), and its discharge from the internal
surfaces previous to the fatal termination.

XXI.

——————

tir kl
Pu Se

;

PLATE XVII

i= : ~ w ——— Ling i tar the Royal Soc. Trans, Page 299 N?

MOE

OTN

SON iy ae

Telescopic Appearance of SUAPS,as ebserved in the Greenland Sea, during avery peculiar

state of the Atmosphere. June 282 1820. Latitude 73° 36 ? Longitude UL GOW.

Telescopic Appearance of the East Coast of” GREENLAND, «athe Distance of 35 Miles, when under the

influence of an extraordinary Refraction, Silty 1801820. Lat. 7? 20) Longl7? 30 W.

and al fae observed ir in lie Greenland Sea. By

Wanna Sconespy, Esq. J jun., F. si s. Ep.

é URING the summer of the present year (1820), while na-
vigating with the ship Baffin, the icy sea in the immediate. .
neighbourhood. of West Greenland (the east side), several ex-
tremely curious appearances of distant objects, produced by
the eflective and refractive Eropertics of pe Pgee were

her had been at elatealy es with the wind from the S. E.,
and N. E,, blo ring fresh. © The day alluded to was beauti-
; not a oud, excepting the most delicate cirri, oes

t ee un oO po
pelts i ‘rite wt

eh ok

300 ON ATMOSPHERIC REFLECTIONS AND REFRACTIONS

on the surrounding ice with such rapidity, that pools of fresh
water were formed on almost every piece, and thousands of
rills carried the excess into the sea. There was scarcely a
breath of wind. The sea was as smooth as a mirror. The ice
around was crowded together, and exhibited every variety,
from the smallest lumps to the most magnificent sheets. Bears
traversed the fields and floes in unusual numbers, and many
whales sported in the recesses and openings among the drift
ice. About six in the evening, a light breeze at NW. having
sprung up, a thin stratus, or “ fog-bank,” at first considerably
illuminated by the sun, appeared in the same quarter, and gra-
dually arose to the altitude of about a quarter of a degree. On
this, most of the ships, navigating at the distance of ten or
fifteen miles, amounting to eighteen or nineteen sail, began to
change their form and magnitude; and when examined by a
telescope from the mast-head of the Baffin, exhibited some ex-
traordinary appearances, differing in effect at almost every
point of the compass. One ship bearing NW. by W. (Plate
XVIIL Fig. a. sketch 1.) had a perfect image, as dark and
distinct as the original, united to its mast-head in a reverse
position ; two others (Figs. 6 and c), at NW., presented two
distinct inverted images in the air, one of them a perfect figure
of the original, the other wanting the hull. Two or three
more, bearing about north, of which one only is represented in
the sketch (Fig. d), were strangely distorted, their masts ap-
pearing of at least twice their proper height, the top-gallant-
masts forming one-half of the total elevation ; and, at the same
time, some vessels bearing NNE. and E., exhibited an ap-
pearance totally different from all the preceding. These, five
in number, of which two only (Figs. e and f) are given in the
drawing, were at the distance oftwelve or fifteen miles, and
consequently considerably beyond the natural horizon; but

owing

OBSERVED IN THE GREENLAND SEA. 301

owing to the influence of some peculiar vapour in the air, they
now seemed to advance so near, that they became distinctly
visible, and the ice, for some minutes, appeared beyond them.
Their masts seemed to be scarcely one-half of their proper al-
titude, in consequence of which, one would have supposed
that they were greatly heeled to one side, or in the position
called “ Careening.” Along with all the images of the ships, a
reflection of the ice, in some places in two strata, also appear-
ed in the air. The upper stratum of ice, in which the images
of the ships terminated, was fifteen minutes of altitude from
the apparent horizon. These reflections suggested the idea of
cliffs, composed of vertical columns of alabaster. The stratus,
which occupied the space intermediate between the reflection
of the ice and the horizon, was, in some positions of the sun,
highly illuminated, and shone like a sheet of distant water in a
calm ; but in other cases, as at the time when the annexed
sketch was taken, it was a little darker in colour than the
higher region of the atmosphere. To this fog, or stratus, then,
it is probable all the reflections were owing; the double
images being produced by two or more strata of fog; while a
highly tremulous transparent vapour, resembling the steam of
water before condensation, which could occasionally be dis-
cerned floating across the ice with the breeze from the NW.
and N., occasioned, it is likely, the singular distortions obser-
ved in the form of every distant object seen through it.
Hence, not only ships, but also the ice, was sometimes deform-
ed by the refractive property of this vapour. The verge of
the ice, in one place, became a considerable precipice ; in ano-
ther it appeared like distant land clad with snow ; and a large
hummock on the horizon was reared into the air (Fig. a) in
the form of an obelisk. The appearances now described oc-
curred between 6 and 12r.m. The reflected images of the
ice

302 ON ATMOSPHERIC REFLECTIONS AND REFRACTIONS

ice continued visible above two hours; of some of the ships
about half an hour; and of others, presenting double reflec-
tions, about five minutes. The whole of the phenomena re-
presented in the sketch were seen about the same time ; but
they occupied a much larger extent than could conveniently
be given in a drawing. There were some vessels in the SE.
quarter, which were not in the least changed from their natu-
ral form or dimensions.

The atmosphere was again, in a similar state to that just
mentioned, on the 15th, 16th, and 17th of July. Our latitude
was then 71: 30, longitude 17’ W. Ice-fields and floes, with
many smaller pieces, were in abundance around us. The wind
was extremely light, the sky cloudless, and the temperature in
the shade between 40° and 48°; the sun, at the same time, was
bright, and its rays powerful. On each of these three days, curi-
ous reflections from fog-banks, or refractions from tremulous
vapour, were observed. The ice in the horizon was reflected in
one, two, or three parallel strata, at the altitude, as seen from
the deck of the Baffin, of ten to thirty minutes above the verge
of the sea; and where water occurred on the horizon, a black-
ish-grey undulating streak appeared in the atmosphere above
it, exactly resembling the slight waves produced by a gentle
breeze of wind, of which it was doubtless a reflection. In
some places the reflected ice was in narrow faint streaks; in
others in bold bright patches, resembling cliffs of white marble,
of the basaltic structure. Sometimes the phenomenon ex-
tended continuously through half the circumference of the ho-
rizon, at others it appeared in detached spots, in various quar-
ters. From the deck of the ship, with a telescope, the invert-
ed images of distant vessels were often seen in the air, while
the ships themselves were far beyond the reach of vision.
Some ships at the distance of six or eight miles, like those seen

on

eS ee

———— ore

OBSERVED IN THE GREENLAND SEA, 203

on the 28th of June, were’ elevated to twice their proper
height, and others compressed almost to a line. Hummocks of
ice here and there were surprisingly enlarged ; and every pro-
ment object, in: a. proper’ position, was either magnified or dis-
torted. These appearances, though often visible to the naked
eye, were not generally very, striking; but when examined
through a telescope, they presented an ever-varying scene of
the most interesting imagery. Most of the phenomena now
mentioned were seen on the 16th of July, at five o’clock in
the afternoon. A.stratus was then observed in the east, ex-
tending, north-about, as far as the north-west. In the latter
quarter, including the azimuth of the sun, the sky was whitish

.and resplendent, so that. the fog was concealed in the general

glare.

Another instance-of curious refraction will only be mention-
ed. This occurred on the 18th of July, under similar circum-
stances of weather, &c. as. those already described. The sky
was clear. The tremulous vapour was particularly sensible
and profuse, though perfectly transparent: ‘The temperature
of the air at 9 a, m.,, the time when the: phenomenon was first
noticed, was 42°; but in the evening preceding it must have
been greatly lower, as the sea was in many places covered with
a considerable pellicle of. new ice. Such a. circumstance, in
the very warmest part of the year, must be considered as very
extraordinary, especially when it is known, that ten degrees
farther to the north, no freezing of the sea, at this season, that’
I am.aware of, has ever been observed. The latitude of the
ship was at this time 71° 20’ N., the longitude 17° 30’ W.
Having approached, on. this occasion, so.near the unexplored
shore of Greenland, that the land appeared distinct and bold;
I was wishful to obtain a drawing of it; but on making the at-.

VOL, IX. P. 11. aq tempt,.

304 ON ATMOSPHERIC REFLECTIONS AND REFRACTIONS

tempt, I found I could not succeed with any degree of accura-
cy, since the outline changed as fast as I proceeded. The odd
form of many of the hills, induced me to examine the land with
a telescope from the mast-head, on which, finding it much dis-
figured by refraction, I contented myself with sketching a few
of the most remarkable objects. These, accurately designed,
yet disposed without regard to their proper order, or the mo-
ment of time when seen, are represented in the sketch,
No. II. They afford a tolerable idea of the nature of the
scenery then within view. The land, at this time in sight, ex-
tended from W. to NNW. (per compass); the nearest part
at WNW, being about 35 miles distant. It seemed to be a
barren and lofty country, abounding in mountainous ridges
and peaks. There was much less snow on it than we usually
find on Spitzbergen at this season’: but in other respects it very
much resembles that inhospitable country.

The general telescopic appearance of the coast was that of
an extensive ancient city, abounding with the ruins of castles,
obelisks, churches, and monuments, with other large and con-
spicuous buildings. Some of the hills seemed to be surmount-
ed by turrets, battlements, spires, and pinnacles ; while others,
subjected to one or two reflections, exhibited large masses of
rock, apparently suspended in the air, at a considerable eleva-
tion above the actual termination of the mountains to which
they referred. The whole exhibition was a grand and interest-
ing phantasmagoria. Scarcely was any particular portion
sketched before it changed its appearance, and assumed the
form of an object totally different. It was perhaps alternately
a castle, a cathedral, or an obelisk; then expanding horizon-
tally, and coalescing with the adjoining hills, united the inter-
mediate valleys, though some miles in width, by a bridge of a

single

a

OBSERVED IN THE GREENLAND SEA. 305

single arch, of the most magnificent appearance and ex-
tent. Notwithstanding these repeated changes, the various
figures represented in the drawing had all the distinctness of
reality; and not only the different strata, but also the veins of
the rocks, with the wreaths of snow occupying ravines and fis-
sures, formed sharp and distinct lines, and exhibited every ap-
pearance of the most perfect solidity.

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XXII. Account of the Erection of a Granite Obelisk, of a
single Stone, about seventy feet high, at Seringapatam. By
Aexanper Kennepy, M. D. F. B.S. Epi, &c.

(Read December 3, 1821. )

On the 19th of February last, I had the honour of reading
to this Society, some notices of the mode of working and po-
lishing granite, by the natives of India *.

One object of that paper was, from a view of the immense
masses, which Indian artists are still in the habit of rendering
obedient to their simple instruments, to deduce the probabi-
lity of the similarity, if not of the identity, of the means now
in use among them, with the processes by which the architects
of the ancient world, raised the stupendous monuments which
we still see in existence ; and, as an instance of the very re-
cent exercise of these arts, I mentioned the erection of a gra-
nite obelisk near Seringapatam, to the memory of the late Jo-
stan Wesse, Esq. who died in the year 1805. The late Pro-

_ fessor Prayrare had expressed to me a desire of procuring in-

formation, as to the means by which the erection of this mo-
nument had been accomplished ; and a wish to bring these to
light, as well as my uncertainty regarding the exact length of
the
-_e
* This Paper will be found in the Edinburgh Philosophical Journal, vol. iv.

p. 849.

308 ACCOUNT OF THE ERECTION OF A GRANITE

the shaft of the obelisk, induced me to apply to Colonel
Wixks, who was upon the spot at the time of its erection, for
information as to these particulars. He has, most politely, in
the letter which I shall now have the honour of reading, taken
the trouble of deducing the materials, even from the quarry ;
and has also added, very particular and satisfactory details, of
the means by which the. erection of the obelisk was accom-
plished. Though the exact length of the shaft is still a desi-
deratum, and Colonel Wixxs, from recollection, is inclined to
think it only sixty feet, instead of seventy-five, at which, from
information, I had stated, it; yet it appears from his narrative,
that accident only, prevented the shaft being formed of a single

stone, of the prodigious length of eighty-four feet, which had -

been actually quarried for the purpose, and the difficulties of
erecting which, we can scarcely doubt, would have been sur-
mounted, by the patient perseverance and address. of Hindoo
workmen.

This stone would have. formed a shaft, Pemailecaht longer,
than that of the obelisk now standing in front of St Peter’s, at
Rome. Evetyn* states the height of this obelisk, compre-
hending the base, at 108 feet, and that of the entire stone,
which forms the shaft, at 72 feet. He says that it was re-
erected, “ with vast cost, and a most stupendous invention,”
by Domrnico Fontana, architect to Srxtus the V., and he af-
terwards mentions (p. 129.) having seen representations of
the machines, invented by the architect for this purpose, paint-
ed upon the walls and roof of one of the rooms of the: Vati-
can. Eyreztyn was at Rome i in 1645.

Colonel

* Memoirs, vol. i. p. 108.

OBELISK OF A SINGLE STONE AT SERINGAPATAM. 309

Colonel Wixxs, in a subsequent letter, has removed all
-doubts, as to the abundance of granite in Mysore, by referring
to Captain Basi Haxx’s fine collection, made in India, and
which, he says, he had an opportunity of seeing at St Helena,
when Captain Hatt last returned from India. I shall quote
part of that letter. The Colonel says, “ That collection, I con-
“ clude, is in Edinburgh, and probably in the geological de-
“ partment of the Royal Society. Sevagunga” (one of the
Mysore droogs,) “ is, I think, the most beautiful red granite I
-“ ever saw, and most of the other droogs,—the grey. Tam
“ aware, however, that there is a great deal of rock in the
“ eastern ridge of ghauts, not strictly granite ; schorl, I think,
“ being sometimes added, and sometimes entirely occupying
* the place of felspar.”

It seems almost superfluous to add, that granite is equally
abundant, in many other districts still farther north. The
countries . “glass oe Beder are well-known instances.

‘ ALEX, Kennepy.
«-Edinlinghs Ist Detember 1821,

London, Thompson’s Hotel, Cavendish Square,
a DEAR rage we miei Rat 1821.

Pp eee ty |

cover a6 memoranda of my own, I proceed to answer your
letter, ds well as I can, from memory alone.

“Although I inxiously watched the progress of this interest-
ing work, I as anxiously left it to be exclusively Indian ; and
the design Of the obelisk, was the only aid, afforded by any Eu-
ropéan to the native workmen.

The

Isp see
Ah Fao ae

310 ACCOUNT: OF THE ERECTION: OF A GRANITE:

The accompanying sketch, Plate XLX, will-obviate much ex-.

planation. The obelisk is erected, nearly on the site of the Eed-

gah Redoubt, which made so determined a defenee on ‘the 6th.
F ebruary 1792 ; and the view is.taken. from the north, with the

: Fort of Seringapatam in the back-ground ; a:bungalo for the ac-
- commodation of visitors, and of a gardener, is seen on the left ;
and more jin the fore -ground, the. carriage on which the shaft

of the obelisk, ;, was conveyed. from the quarry, supported by

_ eight wheels ¢ or ‘rollers, four without, and as many within, the
cheeks of the machine.

_ The plinth, as exhibited in the: sketch, was about. 1+ feet
thick, of three stones of equal dimensions, accurately ae and
resting on three similar stones: at, right angles with those un-
der ground ; the latter, I think, supported by. the solid: rock,
levelled. for their, reception.

_ The pedestal, of a single stone, was nine feet high, and I
think seven feet, wide ;, for I distinctly recollect the base of the

shaft, to have been six feet diameter. An excavation of ec

exact diameter, was made in the summit of the pedestal, ce)
about three inches deep, for the reception of the base; which
excayation, with a ledge or border, of about six inches wide,
between the shaft, and: the exterior of the pedestal, would
make up the seven feet.

According to my recollection, the length of the shaft is not

_ quite 60 feet ; but as every other person. who has been refer-.

red to, states it from memory, at 70. feet at the least, the point

can only be determined by actual measurement.

I well recollect, that the first stone quarried for the purpose
was 84 feet, and that it was moved a few yards, It was bro-
ken by an explosion of gun-powder, intended to split a de-
tached stone, which stood in the line of its intended removal,

and, as the workmen erroneously supposed, sufficiently distant,

not

} ‘

OBELISK OF A SINGLE STONE AT SERINGAPATAM. 311

not to affect the shaft by the concussion of the air. The diffi-

- culty, however, which they found, in giving a slight degree of

motion to this mass, determined the Dewan to contract his
views, regarding the height of the obelisk.

The column was quarried about two miles from the place
where it was erected. In the process of quarrying granite,
two methods are employed.

First method.—The workman looks for a plain naked sur-
face of sufficient extent, and a stratum of the proper thick-
ness, sufficiently near the edge of the rock, to facilitate the
separation, or made so, by previous trimming. (I do not
speak of stratified granite, from any disrespect to the re-
ceived doctrines of geology, but because I know of no other
term to indicate the sort of division in question. I have
repeatedly seen quarriers at work, on extensive strata, of vari-
ous degrees of inclination, and different thickness, from six
inches to eight feet.) The spot being determined, a line is
marked along the direction of the intended separation ; and a
groove of about two inches wide, and the same depth, is cut
with chisels, or if the stratum be but thin, holes of the same
dimensions, at a foot and a half, or two feet distance, are cut
along the line. In either case, all being now ready, a work-
man, with a small chisel, is placed at each hole or interval,
and, with small iron mallets, the line of men keep beating on
the chisels, but not with violence, from left to right, or from
right to left; this operation, as they say, is sometimes conti-
nued for two or three days, before the separation is effected.
Those who have observed the mode of cutting (as it is called)
plate-glass, will not be surprised at their beating from one
end, and the fissure also taking place, from one end to the
other. This is the mode by which the stone in question was

separated.
VOL. IX. P. II, RT Second

312 ACCOUNT OF THE ERECTION OF A GRANITE

Second method.— A groove or line of holes being effected as

above, a narrow line of fire, of bratties (cakes of dried cow- -

dung) is made ; and when the line of rock has been thus tho-
roughly heated, a line of men and women, with pots full of
cold water, suddenly sweep off the ashes, pour the water on
the heated line, and the rock immediately splits, but not so
correctly as by the former process, which makes a cut as clean
as that of a plate-glass manufacturer ; but the last method, as
the cheapest, is employed where great exactness is not requi-
site. It is perhaps Hanwisat’s method, and physical reasons
are not wanting for the conjecture, that vinegar might possibly
be found more effective than water, not for softening, but for
rending heated rocks.

The obelisk was first blocked out in the rough, to lighten it,
before being’ placed on its carriage, by means which will easi-
ly be conceived, after describing those used for its erection.
The carriage, after repeatedly sinking into the hard road, as
into a swamp, was ultimately moved, over a succession of balks
of timber, placed for its support. Granite is so excessively
brittle, that it was thought hazardous to employ draught cattle,
or any power less manageable than that of men ; and the num-
ber employed at one time, on the drag-ropes, as well as I can
venture to say, from the picture left on my memory, was about
600 men. The operation of removing it was extremely tedi-
ous; but I cannot, from: recollection, answer your inquiries
with regard to the exact time, or the expence, of the different
parts of the process.

To shorten my description, I must anticipate a little, by re-
questing’ you to conceive the shaft finished, and placed ready
for erection, in a horizontal position, raised’ to’ the proper
height, and with its base accurately placed for insertion in the
top of the pedestal, when it should attain a vertical position.

Then

OBELISK OF A SINGLE STONE AT SERINGAPATAM. 318

Then imagine a strong wall, built, at right, angles with the line
of the shaft, and a few feet beyond its smaller end ;) with two
lateral retaining walls, parallel. to. the shaft, anda. fourth, of
smaller elevation, near the’ pedestal, to support. the. mass. of
earth, and the workmen to be-employed. On. such a platform,
raised 103 feet, you will, in the first. instance, conceive, the,
shaft to be horizontally arranged... Two lines of timber, plank
or balk, were then ranged along the two sides of the shaft, to
serve as fulcra, and two lines of men, with hand-spikes, attend-
ed by others ready with chocks, or pieces of timber, of differ-
ent thickness, to be inserted under the shaft, for the purpose
of keeping the elevation of the smaller end, effected by the
hand-spikes, and distributing the pressure so equally, as not\to
risk the accidents which would otherwise be? inevitable, with
this very fragile substance. »In proportion as elevation was
thus gradually obtained for the smaller:end, the; space below
was filled with rammed earth, and the same process was’ re-
peated, with the’ parallel: balks of timber, *hand-spikes, :and
chocks: the small end gradually rising at each successive step,
the wall behind increasing im height, ‘arid:an inclined plane. of
solid ‘earth gradually increasing its angle with the:horizon, un-
til it equalled that at which’ solid ‘earth could with safety be
employed : when the force required being proportionally dimi-
nished, timber alone was employed for its elevation: |» Finally,
a scaffolding of timber was erected, ‘embracing three sides of
the pedestal, and nearly equal to the ultimate height of the
obelisk ; ropes were applied to the summit of the shaft, in
such directions as to steady and check it ; hand-spikes gave the
requisite impetus, until it felt the power of the ropes, and was

ultimately, and safely lodged, in its shallow receptacle.
There was one part of the process, which greatly arrested my
agEneiG, from its extreme simplicity. I was satisfied with the
rr 2 means

814 ACCOUNT OF THE ERECTION OF A GRANITE

means taken, for insuring a true horizontal surface, for the base
of the shaft ; but its stability entirely depended, on equal accu-
racy, in the surface of its receptacle, on the summit of the pe-
destal ; and seeing no mode by which, with their rude instru-
ments, this object was to be attained, I so far departed from
my first intention, as to offer them a spirit-level, and instruc-
tions for its use. They quickly understood and admired the
contrivance, but were afraid of venturing on new methods ;
their own was (as they affirmed) more slow, but equally cer-
tain, and they invited me to inspect it. The surface was rub-
bed clean and dry, and some water was dropped on it; the
water ran! “ You see” (said the engineer) “ the high and the
“ ow.” He dried up the water, and applied the chisel to the
higher portion of the surface, and, by the patience and perse-
verance of several days, the surface was perfectly polished, and
a drop of water remained stationary wherever it was placed.

The whole obelisk received a very fair degree of polish from
corundum. A piece of plank is overspread with the sort of ce-
ment, used for setting sword-blades in their handles : while this
substance is still liquid, it is mixed and powdered over, with
pulverised corundum, (reduced to a coarse or fine sand, ac-
cording to the purpose for which it is intended), and left to
dry in the sun. These planks, weighted over, are then used,
like the slabs of the stone-polisher in England. The knife-
grinders wheel, as you probably know, is made of the same
materials.

Inscription

a

OBELISK OF A SINGLE STONE AT SERINGAPATAM. 315

Inscription on the Pedestal.

Erected to the memory of
JOSIAH WEBBE, Ese.

BY

PURNEAH DEWAN,
A tribute of respect and veneration,
For splendid talents,
Unsullied purity,

And eminent public virtue.

No tribute to public merit was ever more spontaneous and
sincere; and the inscription was made as exact a transcript as
possible of the avowed sentiments of the extraordinary Bra-
min Minister, by whom the obelisk was raised.

It is obvious, that the mode of erecting a column must be
very different from that of raising the immense stones which
we see in the walls of Indian temples. ‘These stones are mo-
ved, end foremost, up an inclined plane of solid earth, of as
small an angle with the horizon as circumstances admit, to the
spot which they are to occupy in the wall. Long bamboo
poles, lashed to the stone, at right angles with its length, and
at such distances as merely to admit the efforts of rows of la-
bourers between, constitute the chief means of propelling it, by
main force, up the inclined plane; and its ascent is facilitated,
by means of rollers of small diameter, successively introduced
under the stone, and prevented from sinking into the earth,
by rows of planks placed on each side of the stone, parallel to

the

6

- 316 ACCOUNT OF THE ERECTION OF A GRANITE OBELISK, &c.

1
the line of ascent. When it has ascended the desired height,
it is twisted horizontally round, by similar means, into its de-
stined position.

If I have any where been unsuccessful in making my de-
scription intelligible, I shall be happy to give any farther ex-
planations in my power. I am, &c.

M. Winks.

To Dr paaeiaits
Edinburgh.

XXII.

PLATE XX.

© Drawn & Eng? by WiiTivears

*

Lear es

iS a Sten ene
SOE gy se a eee ER Re”

377.

PLATE XxXI

Fig. 3

XXIIL Account of a Remarkable Structure in Apophyllite, with
Observations on the Optical Peculiarities of that Mineral.
By Davin Brewster, LL. D. F. R.S. sib & Src. R. S.

Ep.

(Read 21st April 1817, 5th March and 17th December 1821.

Tue paticty of Apophyllite to which I have given the name
of Tesselite *, from the beautiful combination of tessele which
it exhibits in polarised light, is one of the most singular sub-
_ stances in the mineral kingdom. The agency of that species
of: light, indeed, seemed necessary to the developement of its
- peculiar structure; but I have since succeeded in confirming
and extending my former results, by the application of the mi-
croscope; and have been led to observe several new pheno-
mena, which not only throw much light on the structure and
properties of this curious mineral, but which affect the funda-

‘mental principles of crystallography.
_ The tesselated Apophyllite from Faroe crystallises in ight
Ra siise prisms, with flat summits, which generally nee
at

* My first experiments on Apophyllite are published in the Edinburgh Philo-
sophical Journal, vol. i. p. 1.

318 ON A NEW STRUCTURE IN APOPHYLLITE, AND

at the angles very minute truncations, inclined 120° to the
edges of the prism *, or 150° to the summit. The sides of the
rectangles are nearly equal, and are commonly about ;’;th
of an inch, while the length of the prism seldom exceeds
2'th tenths of an inch. The four faces of the prism have
an irregular surface, with longitudinal striz, but are high-
ly polished ; while the flat summits display an inferior lustre,
and are variegated with the pearly tints which have given to
this mineral one of its most common names f, and which arise
from the imperfect contact of the elementary lamin. These
laminz, whose surfaces are perpendicular to the axis of the
prism, may be easily separated, to any degree of thinness, by
applying, with the hand, the edge of a sharp knife or lancet ;
and it is no doubt owing to the laminated structure, and to the
imperfect surfaces of the lamine, that a dilute acid, which will
not corrode the polished faces of the prism, will act freely on
its less resisting summits.

When we remove the uppermost slice from each of the two
summits of the crystal, to the thickness of the 100th of an
inch or more, and examine it either by the microscope or by
polarised light, we perceive no tesselated structure. A num-
ber of veins appear at the edges MO, ON, NP, PM, as shewn
in Prats XX. Fig, 1., or at A, Fig. 2. and these veins gradu-
ally diminish in number the nearer we come to the summit,
though they never disappear.

If we now remove the next slice, and all subsequent
slices, between’ the two summits, we shall find that they exhi-

bit

* Haiy makes this angle 117° 48’,

+ Ichthyophthalmite, or Fish-Eye Stone, These pearly tints occur only in one
variety of the Tesselite,

‘ON THE OPTICAL PECULIARITIES OF THAT MINERAL. 319

bit by the microscope, under favourable circumstances of illu-
mination, the beautiful figure represented in Fig. 1, and 2. The
outer case MONP, Fig. 1. which binds the interior parts toge-
ther, is composed of a great number Ofparallel veins, which, from
their minuteness, display the colours of striated surfaces. This
external coating envelopes no fewer than nine separate crystals,
viz. the central lozenge abed, the four prisms A, B, C, D,
with trapezial bases, and the four triangular prisms e hl, imn,
nkg, gfe, all of which are separated from one another by
distinct veins. The inflected lines ehl, mn, nk g, gfe, are
most easily seen by the microscope. The central lozenge is
seen much less frequently, and the radial lines ha, ch, fd,
bm, require a particular mode of illumination to be distinctly
recognised. The colours displayed by one of these plates,
when crossed with an uniform plate of sulphate of lime, having
a polarised tint of a blue colour, is shewn in Plate XXI. Fig. 2.
In some plates the whole of the triangular space e fg, Plate XX.
Fig. 1. has the same colour and structure as A ; gkn the same
as C, and so on; while, in other plates, part of the veined
border belonging to A, has the colour and structure of C; but
the most common effect is that shewn in Fig. 2. of Plate XXI.

In order to discover if there was any form intermediate be-
tween the summit plate and the tesselated laminz, I have cut
up various crystals, but have not been able to observe a gra-
dual transition from the one structure to the other. It must,
therefore, take place either per saltum *, or the one must pass
into the other by a curve; whose vertical branch is less than
the 200th or 300th of an inch.

VOL. IX. P. Il. SS Although

* More recent observations have proved this to be the case, as will be seen in a

subsequent part of this paper.

320 ON A NEW STRUCTURE IN APOPHYLLITE, AND

Although I have examined some hundred crystals of this
variety of Tesselite, I have never yet found one which was tran-
sparent across the faces of the prism, or which could be de-
tached from its bed in a complete state. The second or third
plate is often very transparent; but the incipient separation of
the laminz which produces the pearly lustre, renders it im-
practicable to examine the structure of the crystal across the
faces of the prism. In one specimen, however I succeeded
so far as to determine *, that in it, “ and én several of the Py-
“ ramidal crystals, the maximum tint decidedly varied in dif-
“ ferent parts of the length of the prism, so as to produce a
“ succession of coloured bands at the same thickness +.”

A

* See Edinburgh Philosophical Journal, vol. i. p. 5.

+ In an ingenious memoir, “ On certain remarkable instances of deviation from
“ Newron’s scale, in the tints developed by crystals with one axis of double refrac-
* tion, on exposure to polarised light,” published in the Transactions of the Cam-
bridge Philosophical Socicty, vol. i.; and reprinted in the Edinburgh Philosophical
Journal, vol. iv. p. 334; and vol. v. p. 8334, Mr Herscuet has, I think, mis-
conceived the full import of this experiment. ‘‘ This alternation,” says he, ‘“ or
superposition of laminz of different polarising powers, is no hypothetical case. I
have observed its occurrence not only in the instance before us, but in other crys-
tals of perfect regularity in their external forms. Dr Brewsren has also observed
phenomena referable to this principle in his paper on the Apophyllite.” Upon re-
examining the passage m my paper, Mr HenscHen will, I am sure, agree with
me in thinking, that the phenomena which I observed are not merely referable
to that principle, but are a complete demonstration of it, and distmetly prove,
that in several crystals there were as many “ lamine of different polarising
“ powers,” as there were “ successions of coloured bands at the same thick-
“« ness.” The crystals, indeed, of the specimen which I employed, were the
upper portions of those represented in Plate XXI. Fig. 1. The bending and in-
equalities of the fringes, too, which I have described, and represented in Fig. 7.
of my former paper, establish in the clearest manner the alternation, as well as the.
existence, of different polarising powers in the planes parallel to the faces of the-
pyramid.

ON THE OPTICAL PECULIARITIES OF THAT MINERAL, 321

A general idea of the structure of this variety of Apophyl-
lite, may be obtained from Fig. 2., where A and B are the ter-
minal laminz, raised up in order to shew the tesselated struc-
ture of the intermediate portion of the prism.

The fine transparent pyramidal crystals which are found in
Iceland, as well as in Faroe, possess a tesselated structure,
which differs in several respects from that of the quadrangular
prisms. The arrangement of the tesselze is shewn in Fig. 3.,
but the border ABCD, which is seen only under favourable cir-
cumstances of illumination, appears to be composed of lines or
parts at right angles to the sides AB, BC, &c. ; and the polari-
sing force of the borders is extremely weak. In order to observe
how the tesselze varied in different parts of the crystal, I took
one of the largest I could obtain, and cut it into four different
slices. No part of the substance was removed by grinding or
polishing, so that I examined the structure of the plates as
they were detached in succession from the summit of the crys-
tal : The phenomena which they displayed are shewn in Figs. 4,
5; 6,7; 8,9; Figs. 4, 6, 8, containing the appearances when the
sides of the crystal were in the plane of primitive polarisation ;
and Figs. 5,'7, and 9, when they were inclined 45° to it. The
Figs. 4, and 5, exhibit the tesselz in the first and second slices of
the crystal, which had nearly the same structure. In Figs. 6,
and 7., the figure exhibited by the third slice is shewn. The
angles display a veined structure when examined by the mi-
croscope; and, what is very remarkable, there are two
- central squares ; the interior one being much darker than the
other, and having one axis of double refraction, while the
other exhibits the effect of two axes, as if the axis in the plane
of the laminz had a less polarising force than the correspond-
ing one for the rest of the plate. This effect, however, is likely
to arise from the juxtaposition of two contiguous laminz, abc d

ss 2 and

322 . - ON A NEW STRUCTURE IN APOPHYLLITE, AND

and c def, Fig. 10., the one of which has its central lozenge w
greater than the lozenge m of the other. Hence it follows, that
the compound plate will produce such an effect, that the parts
of the lozenge n surrounding m will appear to have two axes
of double refraction, while the effect is actually produced by
the biaxal structure round the lozenge m of the upper plate
abcd. Inthe fourth slice, represented in Figs. 8 and 9., the
four veined angles. now meet one another, and surround the

-tesselze with only one central lozenge. The slice from below
this, or the fifth, exhibited a very irregular structure.

When all the four slices were together, they distinctly pro-
duced the tesselated structure shewn in Fig. 3. Their united:
thickness was 0.12 of an inch.

When the crystal was examined across two opposite surfaces
of the pyramid, it exhibited the fringes shewn in Fig. 7. of my.
former paper, and in Fig. 11. of the present one; the fringes
being all bent as they approached the edges, where they be-
came serrated, which proves that the polarising force of the
outer coats is less than that of the interior ones, and that the
different coats near the edges have an alternation of different
polarising powers-**. Near the base-of one of these-pyramids,
as shewn in Fig. 11., the curves which had been convex towards
the summit became concave in the middle, though they still
retained their convexity at their junction with the serrated
portions, so as to have the form of curves of contrary flexure.
Another crystal from Faroe produced the opposite effect, as
represented in Fig. 12. ; the isochromatic lines being now con-
cave-towards the summit, and displaying a very rapid variation

of

* See Edinburgh Philosophica! Journal, vol. i, p,.4., and Plate I. Fig. ”,

ON THE OPTICAL PECULIARITIES OF THAT MINERAL. 323

of curvature. - In this specimen, the isochromatic lines are all
eurves of contrary flexure, and there is only a small portion of
them serrated, between their acute convex summits, and the
faces of the pyramid. When some of the Faroe pyramids are
examined: with high powers, and by light transmitted exactly
parallel to their faces, we may recognise frequently three, and
sometimes more minute veins’ parallel to each face, as repre-
sented in Fig: 11. In these veins, the doubly refracting and

polarising forces suffer an instantaneous, change, and portions

of the isochromatic curves are displaced, and thrown, as it were,
towards the summit,of the pyramid, exactly like the dislocations
and slips which take place in strata of coal.

Among the pyramidal crystals from Faroe which Major Px-
TERSEN was so good as to present to me, there was one of un-
usual magnitude, and of a yellowish tinge, which had a num-
ber of additional facets, as represented in Fig. 13, These fa-
cets; shewn at o and p,. were all: inclined 150° to the summit
plane. -In a great number of the Iceland crystals, I have ob-
served four pair of very singular rounded planes, replacing the
angles of the rectangular prism. These planes, which are al-
ways rough, with a certain degree of polish, are shewn at m, n

im Fig. 13., and, with the other faces, constitute a twelve-

sided prism of a very unusual kind; the mean inclination of.
the rounded faces being about. 150...

Among the various forms in which the Apophyllite occurs;
there is one from Faroe of a very interesting nature. The
erystals have a greenish-white tinge, and are aggregated to-
gether in masses. The quadrangular prisms are in general
below one-twelfth of an inch in width; they are always unpo-
lished on their terminal planes; they have the angles at the
summit more deeply truncated than the other quadrangular
él prisms.

324 ON A NEW STRUCTURE IN APOPHYLLITE, AND

prisms from Faroe; they are always perfectly transparent,
and may sometimes be detached in a complete state, with
both their terminal summits.

In examining this variety of Apophyllite, of which I was fa-
youred with a very fine specimen from the excellent cabinet
of Dr Macponatp, I was enabled, by the perfection of the
crystals, to study their structure, through the natural planes, and
at right angles to their axes. The phenomena which this inves-
tigation presented to me, were of a very singular and unex-
pected nature. In symmetry of form, and splendour of colour-
ing, they far surpassed any of the optical arrangements that I
had seen, while they developed a singular complexity of struc-
ture, and indicated the existence of new laws of mineral orga-
nisation.

When a complete crystal of this variety of Apophyllite is ex-
posed to polarised light, with its axis inclined 45° to the plane
of primitive polarisation, and is subsequently examined with
an analysing prism, it exhibits, through both its pair of pa-
rallel planes, the appearance shewn in Plate XXI. Fig. 1. In
turning the crystal round the polarised ray, all the tints vanish,
reappear, and reach their maximum at the same time, so that
they are not the result of any hemitropism, but arise wholly
from a symmetrical combination of elementary crystals, possess-
ing different primitive forms, and different refractive and polar-
ising powers. The difference in the polarising powers is well
shewn by the variation of tint ; and the difference of refractive
power may be observed with equal distinctness, by examining
the crystal with the microscope, under favourable circumstances
of illumination, when the outlines of the symmetrical forms,
shewn in Plate XXI. Fig. 1. will be clearly visible.

In examining the splendid arrangement of tints exhibited in
the figure, the perfect symmetry which appears in all its parts

is

ON THE OPTICAL PECULIARITIES OF THAT MINERAL. 325

is particularly remarkable. The existence of the curvilineal
solid in the centre ;—the gradual diminution in the length of
the circumscribing plates, in consequence of which they taper,
as it were, from the angles of the central square to the trun-
cated angles at the summits; but, above all, the reproduc-
tion of similar tints on each side of the central figure, and at
equal distances from it, cannot fail to strike the observer
with surprise and admiration.

The tints exhibited by each crystal vary of course, according
to its thickness *, but the range of tint in the same plate, and
at the same thickness, generally amounts, in the largest crys-
tals, to three of the orders of colours in Nerwron’s scale.
The central portion, and the two red squares, have, in general,
the same intensity, while the four green segments round the
central portion, and some of the parts beyond each of the
red squares, are also isochromatic t+. In the central part, the
colours have a decided termination ; but towards the summits
of the prism their outline is less regular, and less distinct-
ly marked ; though this irregularity has also its counter part
at the other termination. A part of these irregularities is some-
times owing to the longitudinal strie { on the natural faces of

. the

* In comparing the polarising forces of different crystals of this variety of Apo-
phyllite, I have been surprised to observe the great diversity which exists among
them; some of the prisms, which are only ,,th of an inch thick, having a greater
polarising force than others which are ,th of an inch thick.

+ In some crystals the two smaller green segments have a different tint from ;
the two larger segments, and the same tint as the central square.

+ Owing to the feeble polarising power of the apophyllite, these superficial irre-

gularities produce’a less degree of derangement in the tints than might have.been.

" expected.

326 ON A NEW STRUCTURE IN APOPHYLLITE, AND

the crystal, so that by carefully grinding these off, the beauty
and regularity of the figure is greatly improved.

In order to ascertain the order of the colours polarised by
the crystal, and observe in what manner they passed into one
another, I transmitted the polarised light in a direction pa-
rallel to one of the diagonals of the quadrangular prism, and
thus obtained, as it were, a section of the different orders of
colours, from the zero of their scale. The result of this expe-
riment, which is shewn in Fig. 14., was highly interesting,
as it displayed to the eye not only the law according to which
the intensity of the polarising forces varied in different parts of
the crystal; but also the variation in the nature of the tints,
and the connection between these two classes of phenomena.
At the points in the diagonal mn, opposite to a and b of the
crystal, the tints rose to the seventh order of colours; at other
two places, opposite to ¢ and d, they rose only to the sixth ;
while near the summits, at m and n, they descended so low
as the fourth order. Hence it follows, that the portions at
a, a, have the maximum polarising force ; that the four seg-
ments coloured green in Plate X XI. Fig. 1., are next to these
in intensity ; that the central pertions of the red squares are
again inferior to these ; and that the weakest polarising force
is near the summits of the prism. At a and 6 the 4th, 5th and |
6th fringes, have a singularly serrated outline, exhibiting in a
very interesting manner the sudden variation which takes
place in the polarising forces of the successive lamine. Al-
though the variation in the polarising power of the succession
of circumscribing plates, is clearly represented by the differ-
ences of tint shewn in Fig. 1. of the coloured engraving, yet
the exact amount of that variation may be rendered evident,
by making the isochromatic lines cross these plates, and ob-.
serving the serrated outline which is thus produced. ee

In

ON THE OPTICAL PECULIARITIES OF THAT MINERAL. 327)

_ In some crystals of this variety of Apophyllite; particularly
in the smaller ones, the central portion is only 3th of the whole
length of the prism, and the maximum polarising power re-
sides in that central part. This last effect is shewn in Fig. 17.
where the first fringe is completed in the form of a rectangle
enclosing the central portion, while, in the other parts of the
prism, the tint has not risen above the yellow of the first order.
- Having thus ascertained the properties of the prism, when
examined through its parallel faces, I proceeded to determine its
structure at right angles to the axis, by observing the pheno-
mena which the separate laminez exhibited, in relation to the
part of the prism from which they were extracted.
_ The plates near the summit of the crystals are exactly the
same as the uppermost slice A, Fig. 2. of the Apophyllite al-
ready described. The subjacent plates are also similar, with
this difference only, that the veined border increases in
breadth, and is often beautifully divided into groups of veins,
like the: frame of a picture ; and they retain nearly the same
: character till we reach the central figure. At this point the in-
flected lines eh J, &c. shewn in Fig. 1. appear within each of the
four inner sides of the border; and when seen by polarised
light, the slices of the central figure exhibit the tesselated
structure shewn in Fig. 16., with some slight modifications.
It is very remarkable, however, that when these same slices
are examined with a microscope, the figure which they display
is different from Fig. 16., and resembles the structure shewn
in Fig. 15. In Fig. 16. some of the quadrilateral outlines
which form the border, have the planes passing through the
two axes at right angles to those of others; from which it
follows, that some parts all round the border are luminous,
and others dark, when the diagonal is in the plane of polarisa-
tion, and vice versd when the diagonal is inclined 45° to this
plane.
VOL. IX. P. II. Tt There

328 ON A NEW STRUCTURE IN APOPHYLLITE, AND

There ‘is another variety of Apophyllite from Greenland, of
a very interesting kind. Sir Cuartes Gresecxe’, who kindly
communicated to me several specimens of it, discovered it at
Kudlisaet in Disco Island*, and describes it as of a cylindri-
cal form, presenting the shape of a barrel, from being con-
tracted at the extremities.

Upon examining some of the best specimens of this mine-
ral, I find that each of the four curvilineal surfaces, by which
the prism is contained, often consist of three planes, inclined
to one another at very great angles. There is a distinct trun-
cation, too, upon the angles at the summit, and its inclina-
tion is nearly the same as in the perfect crystals.

As all the transparent crystals which I have seen of this mi-
neral, are intersected with diverging groups of capillary meso-
type, or, more probably, capillary apophyllite, it is not unlike-
ly, that the usual law of its crystallisation has been modified
by its formation either at the extremity of one, or in the
middle of several groups of these filamentous crystals f.

When the uppermost slice of this kind of Apophyllite is cut
off, it has only one axis of double refraction, like the same
slice of the regular quadrangular prisms, and displays no tes-
selated structure.

The second slice exhibits a tesselated appearance, which va-
ries in different crystals, as represented in Figs. 18. and 19. In
both these figures, the shaded part has only one axis of double
refraction, while the five sectors have two axes, and the plane

passing

* See this Volume, p. 270.

+ There are many examples of Apophyllite having been deposited upon groups
of Needlestone; but in these cases, the crystal is not penetrated by them, but
merely rests upon their filaments.

ee

ON THE OPTICAL PECULIARITIES OF THAT MINERAL. 329

passing through the resultant axes of the sectors A and C, is at
right angles to the plane passing through the resultant axes of
Band D. In Fig. 18. the tints gradually increase from the
centre to the angles A, B, C, D, from the black, or zero of the
scale, to the yellow of the first order. In Fig. 19. the tints
are uniformly the white of the first order, which is immediate-
ly followed, upon inclining the plate, with the most brilliant
gamboge yellow, and then green *.

Having thus described the remarkable structure of Apophy]-
lite, I shall now direct the attention of the Society to the ge-
neral optical properties of this mineral.

_ In the ingenious and elaborate memoir of Mr Herscuet, on
the action of crystallised bodies on homogeneous light, &c.,
read to the Royal Society of London on the 23d Decem-
ber 1819, he has investigated the origin and nature of the
tints which compose the singular system of coloured rings,
which I discovered in Apophyllite in 1816. By examining
these rings, he found that they “ indicated an action on polari-
sed light very nearly the same for all the colours, being equal
upon the red and indigo blue rays, a little greater for the yel-
low and the green, and a little less for the violet ;” and hence
he accounted for those unusual tints which characterised this
mineral. gti! .

In a subsequent paper, read before the Cambridge Philoso-
phical Society on the Ist May 1820+, Mr Herscuex confirm-
ed and extended these observations. He found that the law
of proportional action was so far subverted in a particular spe-
cimen of Apophyllite, that the periods performed by a red ray
prey Tt 2 were

* The mechanical structure of the cleavage planes resembles the optical figure
~ even after the planes are ground.

4 + Published in their Transactions, vol. i.; and in the Edinburgh Philoso-
phical Journal, vol. iv. p. 334.; and vol. v. p. 334.

330 ON A NEW STRUCTURE IN APOPHYLLITE, AND

were shorter than those passed through by a violet one. The
rings exhibited a complete inversion of the Newtonian scale,
and the red rays were so much more energetically acted upon
than the violet, that the whole prismatic spectrum was display-
ed in the first ring.

In athird memoir, read before the Cambridge Society on the
7th May 1821, but not yet published, Mr Herscues has resumed
the subject of these anomalous actions upon light. “ Upon re-
considering his results, it appeared that these specimens (viz. of
Apophyllite, which produced an inversion of the Newtonian
scale) could not be referred exclusively either to the class of at-
tractive or of repulsive doubly refracting crystals, nor to the inter-
mediate class, which is devoid of the property of double refrac-
tion. They appeared to belong at once to all the three classes
of media just mentioned, possessing the property of attractive
crystals, when exposed to the rays forming one extreme of the
spectrum, and of repulsive, in their action on the other ex-
treme; while, for certain intermediate rays, they were altoge-
ther devoid of the property of double refraction. Mr Her-
scHEL was led to this inference, by observing, that the curves
whose ordinates represented the polarising energy, after ap-
proaching very rapidly to the axis, would again recede rapidly
trom it on the same side, except the ordinates were supposed
to become negative, which appeared more probable. This in-
duced him to examine the truth of his supposition, by mea-
sures taken in homogeneous light, and the result was a com-
plete confirmation of the remarkable singularity above no-

ticed *,”” .
Although we cannot doubt the accuracy of these interesting
results, yet it must be remembered, that the property which
they

* Proceedings of the Cambridge Philosophical Society, in the Edinferel Phi-
losophical Journal, vol. v. p. 213.

SX taal

or

pel

Pg i tl’

—s +

ipa

pe
ag ta

ON THE OPTICAL PECULIARITIES OF THAT MINERAL. 331

they establish is not characteristic of any of the varieties of
the mineral, but has been found only in a detached portion of
a crystal. In order to ascertain how far it might be general,
I have examined, with the greatest care, numerous specimens
of’ all the varieties of Apophyllites, including those from Fas-
sa, Utoé, Faroe, and Iceland; but having effected a distinct
separation of the ordinary and extraordinary images, I have
invariably found, that the doubly refracting force was Positive
or Attractive, like that of Quartz, whether the ray was Red, Blue,
or Yellow. We must, therefore, regard the property discover-
ed by Mr Herscuen as an accidental anomaly, having its ori-
gin in some peculiar relation of the polarising forces of Apo-
phyllite. What this relation is, we shall now proceed to con-
sider.

In the Biaxal Apophyllite, one of the polarising axes must be
in the plane of the laminz, and in both the Biazal, and the
Uniaxal Apophyllite, there appears to be an axis perpendicular
to the laminz. As the form of the prism of Apophyllite is
perfectly symmetrical in relation to the axis, it is probable that
there are two equal and rectangular axes, of a Positive or At-
tractive character, in the plane of the lamin, each axis being
perpendicular to the parallel faces of the crystal, and we know
that there is a Positive or Attractive axis at right angles to the
laminz, and coincident with the axis of the prism *. The
two equal Positive axes, which we shall call the Horizontal axes,
on the supposition that the prism is placed upon its base, will
obviously produce a single Negative axis, coincident with

the

* I must refer the reader to my paper ‘‘ On the Laws of Polarisation and
Double Refraction,” in the Phil. Trans. Lond. for 1818, p. 231, and p. 245,—
254. for the grounds upon which this resolution of axes is made. In the case of
Apophyllite, there are reasons of a peculiar kind for SHBERSTEE, the existence of
three axes.

3382 ON A NEW STRUCTURE IN APOPHYLLITE, AND

the other Positive axis, or the Vertical one perpendicular to
the lamina, and the system of rings round the resultant of these
two axes, will deviate more or less from Newron’s scale, ac-
cording to the nature of the dispersive forces of the elementary
axes *. Let us suppose that the resultant negative vertical axis
has the same action upon the Yellow rays of the spectrum, as
the real positive vertical axis ; but that it acts much more ener-
getically upon the Red extremity, and much less energetically
upon the Blue extremity of the spectrum. The yellow rays
being thus solicited by equal and opposite forces, the crystal
will exercise over them no polarising energy. ‘The red rays
being subjected to a greater polarising energy from the Nega-
tive than from the Positive axis, will give rings corresponding
to the difference of their opposite actions, and the characters
of these rings will be Negative. The blue rays, on the contra-
ry, being much less energetically acted upon by the Negative
than by the Positive axis, will form rings proportional to the
difference of their actions, and these rings will be Positive,
from the predominating influence of the positive axis. In this
way, a particular crystal of Apophyllite may exercise over the
red rays of the polarised beam a negative influence; over the
blue rays a positive influence ; and over the yellow rays no in-
fluence at all+; while it is the general character of the mineral to
exert an attractive doubly refracting force over all the rays of

the

* For an illustration of these views, the reader is referred to my letter to Mr
HerscuHeEt, published at the end of his paper in the Phil. Trans. 1820, p. 94. ;
and to Mr Herscuet’s paper in the T'ransactions of the Cambridge Philosophical
Society, vol. i.; or in the Edin. Phil. Journal, vol. iv. p. 335.; and vol. v. p. 340.

+ This partial equilibrium of polarising forces is analogous to the paradoxical
phenomena of a compound lens, which, as I have elsewhere shewn, may be con-
structed so as to converge the Blue rays, diverge the Red rays, and exercise no ac-
tion at all upon the Yellow ones. That is, the same compound lens is a Plane lens
in yellow light, a convew one in blue light, and a concave one in red light.

ON THE OPTICAL PECULIARITIES OF THAT MINERAL. 333

the spectrum.; The ray of: compensation, in, place of being
yellow, may have any position in the spectrum, and those on
each side of it will afford positive or negative tints, according
as the positive or the negative axis exercises over them a pre-
dominating influence.

This view of the polarising structure of Actobulliees affords
a complete explanation of the singular tints which surround
its resultant axis. Each order of colours is. as it. were a resi-
dual spectrum *, arising from the opposite actions of the ne-
gative and the positive axis, and the tints of which these orders
are composed, will consequently vary, according to the loca-
lity of the ray of compensation f+.

Having thus described: the structure and properties of the
tesselated Apophyllite, it becomes interesting to inquire how far
such a combination of structures is compatible with the admit-
ted laws of crystallography. The growth of a crystal, in vir-
tue of the aggregation of minute particles endowed with pola-
rity, and possessing certain primitive forms, is easily compre-
hended, whether we suppose the particles to exist in a state of
igneous fluidity or aqueous solution. But it is a necessary
consequence of this process, that the same law presides at the
formation of every part of it, and that the crystal is homoge-
neous throughout, possessing the same mechanical and physi-
es properties in all “peal directions,

ARE EAM Steen ina The

_* Among the ‘various residual spectra which I have examined in the course

of my experiments “on the Action of Transparent Bodies upon the differently
coloured Rays of Light,” there are many among the polarised rings which have
exactly | the same tint; and there are some which resemble as nearly as possible
those i in Apophyllite. See Edinburgh Transactions, vol, viii, p. 1.

+ The > preceding. explanation may be presented in a more brief form, by stating
that the specimen of Apophyllite i in question had three positive rectangular axes,
which w ere in equilibrium only for the yellow rays of the spectrum. See Phil.
Trans, 1818, p. 256.

334 ON A NEW STRUCTURE IN APOPHYLLITE, AND

The tesselated Apophyllite, however, could not have been
formed by this process. It resembles more a work of art, in
which the artist has varied, not only the materials, but the laws
of their combination.

A foundation appears to be first laid by means of an uni-
form homogeneous plate, the primitive form of which is pyra-
midal. A central pillar, whose section is a rectangular lozenge,
then rises perpendicularly from the base, and consists of simi-
lar particles. Round this pillar are placed new materials, in
the form of four trapezoidal solids, the primitive form of whose
particles is prismatic, and in these solids the lines of similar
properties are at right angles to each other. The crystal is
then made quadrangular by the application of four triangular
prisms of unusual acuteness. These nine solids, arranged in
this symmetrical manner, and joined by transparent veins, per-
forming the functions of a cement, are then surrounded by a
wall, composed of numerous films, deposited in succession,
and the whole of this singular assemblage is finally roofed in
by a plate exactly similar to that which formed its founda-
tion.

The second variety of the Tesselated Apophyllite is still
more complicated. Possessing the different combinations of
the one which has just been described, it displays, in the di-
rection of the length of the prism, an organisation of the most
singular kind. Forms unknown in crystallography occupy its
central portion, and on each side of it particles of similar pro-
perties take their place, at similar distances, now forming a
zone of uniform polarising force, now another increasing to a
maximum, and now a third, descending in the scale by regu-
lar gradations. The boundaries of these corresponding, though
distant zones, are marked with the greatest precision, and all
their parts as nicely adjusted, as if some skilful workman had

. selected

ON THE OPTICAL PECULIARITIES OF THAT MINERAL. 335

selected the materials, measured the spaces they were to occu-
py, and, finally, combined them into the finest specimen of na-
tural Mosaic.
_ Those irregularities of crystallisation which are known by
the name of Macle or Hemitrope forms, and those compound
groups which arise from the mutual penetration of crystals,
are merely accidental deviations from particular laws, which go-
vern the crystallisations in which they occur. The aberrations
themselves testify the predominance of the laws to which they
form exceptions, and they are susceptible of explanation by
assuming certain polarities in the integrant molecules. The
compound structure of the Apophyllite, however, cannot be
referred to these capricious formations. It is itself the result
of a general law, to which there are no exceptions, and when
more deeply studied, and better understood, it must ultimate-
ly lead to the introduction of some new principle of organisa-
tion, of which crystallographers have at present no concep-
tion. ;
The difficulty of accounting for the formation of Apophyl-
lite, is In no way diminished, by giving the utmost licence to
speculation. We cannot even avail ourselves of the extrava-
gant supposition of a crystalline embryo, which, like that of
animal and vegetable life, gradually expands to maturity.
The germ of plants and animals is nourished by a series of or-
gans, of which, however recondite be the operation, we yet see
the action, and witness the effects ; but, in the architecture of
Apophyllite, no subsidiary organs are seen. The crystal ap-
pears only in its state of perfection ; and we are left to admire
the skill which presided at its formation, and to profit by the
instruction which is so impressively conveyed by such myste-
rious ‘organisations.

“VOL. Yx. '?. II. bs U u ’ ‘DE-

(. 386.)

DESCRIPTION OF THE PLATES.

PiatE XX.

Fig. 1. Represents the tesselated structure of one of the internal plates of the Faroe
Apophyllite, as developed in ordinary light by the microscope, or as seen by expo-
sing it to a polarised ray.

Fig. 2. Represents a complete crystal of the same Apophyllite, with the upper and
under slices lifted’ up, to shew the internal tesselated structure.

Fig. 3. Represents the tesselated structure of the pyramidal crystals of Apophyllite
from Faroe and Iceland.

Figs. 4, 5, 6, '7, 8, 9. Shew the effects produced by successive slices, taken from
one of the pyramids of Apophyllite.

Fig. 10. Is a diagram for explaining the double central lozenge seen in Fig. 7.

Fig. 11. Shews the variation in the curvature of the fringes, or isochromatic curves,
their convexity, as seen through two opposite faces of the pyramid, and the veins
with which they are sometimes traversed, with the slips in the isochromatic curves.

Fig. 12. Represents.a more singular variation in the isochromatic curves, and their
concavity towards the summit, as seen through two opposite faces of the pyramid.

Fig. 13. Represents a complete crystal of the Iceland Apophyllite, with the new
facets 0, p, &c. at the summit of the pyramid, and of the six curyilineal and un-
polished planes m, 7.

Fig. 14. Shews the form of the isochromatic curves, as seen through the diagonal
of a quadrangular prism of a transparent variety of Apophyllite from Faroe,
the structure, through its parallel faces, being shewn in Plate XXI. Fig. 1.

Fig. 15. Represents the structure, as detected by the microscope of one of the cen-
tral lamine or slices of the crystal, shewn in Plate XXI. Fig. 1.

Fig. 16. Shews the optical effect produced by the same lamina or slice.

‘Fig. 17. Shews the form of the first isochromatic curve in a very small crystal.

Fig. 18. Represents the figure produced in polarised light, by an internal sire of
the Barrel or cylindrical Apophyllite from Greenland.

Fig. 19. Represents the figure produced by a similar slice from another specimen.

PiateE XXI.

Fig. 1. Is a magnified representation of the Figure, and the Tints displayed by a
complete crystal, of a particular variety of Faroe Apophyllite, when exposed to
polarised light. The outlines of the figure are distinctly seen by the microscope

. alone, in ordinary light. ‘The crystal is here magnified about 50 times.

Fig. 2. Shews the colours produced by one of the tesselated laminz of Apophyl-
lite, when crossed by a plate of sulphate of lime which gives one uniform blue tint.

Fig, 3. Represents the circular system of rings, with their anomalous tints, as seen
round the axis of the Apophyllite Surcomposée.

-

PLATE XXII Enyraved tor the Rayal Soc. Trans. Val. X.page 337.

2

Rg?

Fig. 3.

Lis

Wihazars Seulp!

ts

|
yf

XXIV. On the cole of Analysis to the Discovery of Lo- -
i cal Theorems and Porisms. By Cuar.zs Bassace, Ese.
THEE — Lonp. & Eon.

pon (Read May 1, TR )

i “i
1X '*

} i \
axle

én am have devotes aimed of cit attarition to ma-

: thematical i inquiries, must have had frequent occasion to ad-

mire the unexpected and intimate ‘connection which subsists
between branches of their science apparently the most remote
and unconnected with each other; and repeated observation
will have convinced, them, that no researches, however recon-

dite or abstruse, should be neglected, because they appear to

stand isolated and detached from the body of the science.
These reflections appear to have been felt with strongest force,

ere par ularly insisted on by Mactavzny, i in the Preface to
is. Geometri

by those who have 1 most contributed to its advancement, and,

a Organica. The present Paper will add another

example, to instances already numerous, of the latent affinity |
between departments of f mathematics, usually regarded as the

most opposite. .
By those who have studied the writings of the illustrious re-
storers of; the my valuab) e and interesting portion of the an-

Sf u 2 : cient
3 ae

bao. ea a hr et ids abe

ke: | os 2 hoe

-

338 ON THE APPLICATION OF ANALYSIS TO THE DISCOVERY

cient geometry, the views which are here opened may proba-
bly be regarded with surprise, not unmixed with regret, that
the increasing perfection of the language of symbols should
gradually cause it to usurp the hitherto exclusive domains of
the higher geometry. But whatever may be the discoveries to
which the geometrical interpretation of language, at once the
most comprehensive and condensed which human ingenuity
has devised, shall give birth, the restorer of the Porisms of
Eucuip, and the author of the General Theorems, will retain
an undiminished reputation, and their works continue to be
studied, by all those who wish to acquire a correct taste for the
geometry of the ancients. Those propositions which have re-
ceived the appellation of Local Theorems and Porisms, may,
in one point of view, be considered as differing from theorems
and problems, by having something more general, or indeter-
minate, in their nature ; by affirming that some property is pos-
sessed not merely by one individual, but by every one, of
some class or species. It ison this circumstance that the alge-
braic investigation of »porisms is founded : the arbitrary con-
stants of an equation of ‘two variables, are made to submit to
certain conditions, which ‘shall leave the variables themselves
still indeterminate. By generalising this process, we take, in-
stead of arbitrary constants, unknown functions of the variables
themselves; and instead of the resulting algebraic equations,
we find functional equations which determine the form of the
functions we have assumed.

This process, which will be better understood by the subse-
quent inquiries, leads us at once to the highest pitch of ;gene-
rality, and puts us in possession of innumerable iporisms, and
local theorems, each comprehending whole classes of curves.
By limiting and determining the form of the arbitrary func-
tions involved in the ‘solution, we gradually restrict the extent

of

ee ee Se ee

op es ae i

OF LOCAL THEOREMS AND PORISMS. 339

of our results, and we frequently arrive at /oci belonging to the
conic sections. Sometimes, however, the simplification is still
greater, and we are surprised by recognising, amongst exten-
sive classes of curves, possessed of some peculiar property,
some well known docus of the straight line or circle.

The inquiries which follow are given nearly in the order in
which they occurred; a different arrangement might have ap-
peared more systematic, but it would have had thé great dis-
advantage of concealing the means by which the results were
arrived at. Several of the more restricted porisms and local
theorems, might have admitted of a geometrical dress ; but this
would have been inconsistent with the object I had proposed
to myself in the present paper. The greater part are, I be-
lieve, beyond the powers of geometry ; and this opinion, if al-
lowed to be correct, will perhaps, by the admirers of the an-
cient geometry, be admitted as some excuse for the present
attempt to add to its stores, by means so very foreign.

There exist numerous classes of curves possessed of the fol-
lowing property :

If we take any abscissa AE, Plate XXII. Fig, 1, and ordinate
BE, and if we make AF = BE, and find the new ordinate CF,

and repeat the.same process n times, the mth ordinate HI shall

ore

represent the equation of the curve, then the equation deter-
mining the form of ~ will be

iow interme
” the. daibaits of.curves here.alluded to, will frequently occur in
the following :inquirieg, I shall venture to bestow on them the
name.of Periodic Curves, which was suggested by the similar
name assigned ‘by Mr Herscyex to the function which satis-
fies the equation just given. It will also.be convenient ‘to .ap-

ply

equal the first abscissa AE. It is. easy to perceive, that ify = ) x

340 ON THE APPLICATION OF ANALYSIS TO THE DISCOVERY

ply some name to the series of ordinates thus found: I shall
therefore call them Corresponding Ordinates. These curves
may be divided into orders, according to the value of the in-
dex n; if m =1, the first order consists of only one curve,
namely, y= «=a, which is the equation of a right line,
making an angle of 45° with the axis. |

When n= 2, and yf is determined from J:2 =a,

y= yu

represents all periodic curves of the second order, and so on.

The equation "x =z has been solved by me in the Philoso-
phical Transactions for 1816, and numerous examples are gi-
ven in another paper, published in the following year. This
solution has, however, been much improved by Mr Horner
(see Annals of Philosophy, October 1817), who has shewn that
the algebraic equation to which my method of solution leads
in all cases, admits of a ready solution. The form which is thus
assigned to the function Wf is

if atba
seh yess ee ahem Ee
kn
| 2(1+ cos “*)a i

Amongst those included in the second order of periodic
curves, will be found the right-angled hyperbola referred to
co-ordinates parallel to its assymptotes, and also circles of all
orders, where equations are «*-+ y*= a"; these curves pos-
sess many singular properties. All those in which n is even are
re-entering curves, without any infinite branches, whose form is
nearly that of the subjoined figure, Fig. 2. In this curve, if
we take any abscissa, and ordinate CD and BD, and if we turn
the triangle CBD, into such a position that B shall coincide
with the axis CF, then the point C will coincide with G some

point

OF LOCAL THEOREMS AND PORISMS. { 341

point in the curve, and also the arc GF, together with the arc
BF, will be equal to the quadrant AF of the curve.

- Let ABC be any periodic curve of the second order, whose
equation is y= a2, and DB, EC any two corresponding or-
dinates, it is required to find another curve AFG, such that
the sum of its two ordinates, at the points D and E, may be
always a constant quantity.

From the nature of the curve ABC, we have AD =a, and
AE = DB=e2; also «?#= «.
Let y= Ww be the equation of the curve AFG, then
FD= 172, and GE=4 (AE) = a2, and by the prescribed
condition, we have for the equation determining y
Ya+ pare;
the general solution of which is,
Cor
Sa EET CTS
the function ¢ is perfectly arbitrary, and of the class of curves
Cor

gutoax

comprehended in the equation y = , We May enun-

ciate the following porisms.

_ Any of this family of curves being given, a periodic curve of the
second order (ABC), may always be found such, that if we take
any two abscisse in the curve given, respectively equal to any two
corresponding ordinates of the curve found, and draw ordinates
to the given curve, and if we prolong either of these ordinates
(EG) above the curve, until the part above (GH) is equal to the
jirst of the two ordinates, the extremity of the ordinate, thus in-
creased, will always be situated in a right line given by posi-
tion, Fig. 3.

The line thus given by position is parallel to the abscissz,
and situated at the distance denoted by c.

If

342 ON THE APPLICATION OF ANALYSIS TO THE DISCOVERY

If we prolong either of the two ordinates (GE) below the ab-
scisse, by a quantity (EL) equal to the first ordinate, the extre-
mity of the ordinate, thus prolonged, will always be situated in a
curve, similar and equal to the given curve, which is also given
by position.

The position of the given curve is parallel to the original
curve. The deduction of these porisms is so obvious, from
the property of the class of curves, that I consider any farther
explanation of them unnecessary. We shall, however, by as-
signing particular values to some of the functions, find some

very simple results. Let us suppose «2=W/q?—4.’, then
the family of curves will be contained in the equation,

al ¢ 9 (2)
his oa +9 (fa? — a*)’
Of these curves, the following property may be stated :

Any curve of this family being given, a straight line (HK)
may be found through any point, of which, if a line (HD) be
drawn at right angles to the axis of the abscisse, it will cut off
an abscissa (AD), and part of it will form the ordinate (CD), if
an abscissa (AE) be found, whose ordinate (BE) is equal to that
part of the line drawn, which is intercepted between the line found
and the curve ; and if both the two ordinates thus found, be pro-
longed below the axis, until the part of each below is equal to the
abscissa belonging to the other ordinate, the two points to which
these lines are prolonged, are situated in the circumference of a
circle given by position. See Fig. 4.

Let «2 —=—vz, then the curves included in the family —

CPL

ae ox + ¢(—2)

possess the following property :

Any

ee

OF LOCAL THEOREMS AND PORISMS. 343

Any curve of this kind being given, if we take two equal ab-
sciss@, on opposite sides of the centre, and prolong the ordinates
at both these points, until the parts of each produced be equal to
the ordinate at the other point, then the locus of the points thus
found is a right line given by position.

If we make »x—a-+<a, the curve becomes a right line,

whose equation is y= 5 + = 2; and the line found is paral-

lel to the axis, and the curve given, is a right line passing
through a point in the axis of the ordinates, equally distant
from each parallel.

Let ABC be any periodic curve, Fig. 5. and DB, EC, any
two corresponding ordinates; draw the ordinates FD, GC,
and draw the line HFG, passing through the points F and
G, it is required to find the equation of this line.

w and v being the co-ordinates of any point in this line, its
equation will be v= Aw+ B; the quantities A and B being
determined by the condition, that it must pass through the
points F and G, whose co-ordinates are respectively x and } 2,
and «a, and aa, we have

L—Yypar av.ypr—tZ,
ra aie eo weet
Let us now determine the form of the curve AFG by this
condition, that the line HG shall always be parallel to itself.
It is well known, that the co-efficient of the abscissa w ex-
presses the tangent of the angle of the inclination of the line
to its axis ; this must therefore be constant, and we have
ye—tee =c, or Pe—bar=c(e«—aa);
= A : . _ C\#®@—av) or
the solution of this equation is -~ «= cle anes
This suggests the following porisms :
VOL. IX. P. Il. xXx Any

344 ON THE APPLICATION OF ANALYSIS TO’'THE DISCOVERY

Any of ‘the family: of curves contained’ in. the equation
C\eu—awv) or

4A ee te
through any point of which, if a right line be drawn perpendicu-
larly, cutting the curve in two points, and if the ordinate at each
of these points is produced to a point below the axis, until the
part below each is equal to the abscissa belonging to the other or-
_dinate, the two points thus found will always be situated in a pe-
riodic: curve, given in species and position.

The line to which: the other lines are drawn perpendicular,
is at right angles to the line HFG im the figure.

If we make ae = /a? — a, the curve which is the locus of
these points is a circle, whose radius is equal to a, and if we
also make ¢2 = 6, the original curve is an ellipse.

ing given, a right line may be found,

2
If we make «2 = < , and also ¢a = 6, the equation of the
> 2 : ,
given curve is y= 3 («a — 2), which is an hyperbola, and

. 2
that of the curve found is y = < , a right-angle hyperbola.

If in the equation of the right line,

i Abe wet At eee Met
L—ar L—aw 7

we make w-— 0, we have the distance of the point K from A;

let us suppose this to remain constant, then

ad, Paka poe =e Or ae. ve—r.$ar=—ce(r—ar);
L—aL

wi Bes 1 c(w—at)er

the solution of which is ) «= ar. | PR PaL

The

eee ae ee en eee ee ee ee ee eee ee ee

OF LOCAL THEOREMS AND PORISMS. 345

The .class of curves comprehended in the equation
J clev@—ax)owx
wae ae 0 Wot
property :

Any curve of the kind being given, a point (K) may be found,
through which, if a right line (KG) be drawn in any direction,
cutting the curve in two points (F and G), if the ordinate at one
of these points be prolonged to a point below the axis, until the«
part below is equal in length to the abscissa corresponding to the
other point of intersection, then the point thus found is always si-
tuated in a periodic curve of the second order, given in species
and position. Fig. 5. of Sid J

If inthe equation of the line, we make v= 0, we ‘have

» are possessed of the following

_aen.fr—x.bar
Bre per— per
constant, we in fact fix the point K in the axis of the abscisse.
This gives the equation for determining abs

(22—c) Pw= (x —c) var;

, and if we suppose this to remain

os solution is ~x = cyt, wa}
By ee

niet AEG: be any periodic curve, Fig. 6., and AD, AE any
two corresponding abscissze. Required the equation’ of. all
curves, such that the line joining the summits of the two or-
dinates, raised at the points D and E, shall be constant:

The equation of the periodic curve being y= «x; let that
of the family of curves sought be y= 2; ‘then we have
AD=2, AK=az, BD= 2, CE= «a2, and the equation
determining the form of } is

(bax—ypa)?+(ar—ajlP=c’. (a)

xx@2 ; This

346 ON THE APPLICATION OF ANALYSIS TO THE DISCOVERY

This equation is one of those which I noticed in a paper in
the Philosophical Transactions for 1817, p. 211. I there sta-
ted, that it appeared impossible for any function to satisfy the
equation, unless it contained a radicle, and unless different
roots were taken in different parts of the equation. This expla-
nation will perhaps be rendered more satisfactory by the ap-
plication to geometry. The general solution of the equation
In question, 1s

popes Vo? — (a e—x)r _

ry ex+oarx y

where the upper sign must be used in one part of the equa-
tion, and the lower sign in another. From this equation we
learn, that for every value of x there are two values of 7,
equal, but extending in opposite directions; or that the curve
is symmetrical with regard to the axis of the x’s: and since we
must use different values of the radicle, it appears that the two
points B and C cannot be in the same branch of the curve, and
on the same side of the axis, but that one point being situated
above the axis, the other must be placed in the corresponding
branch, which exists below the axis. In fact, it seems to fol-
low, from the very nature of the equation (a), that no curve
possessing this property can have both the two points B and
C situated in the same branch. These considerations render
it necessary, in some measure, to limit the generality of the
function ¢; and it may be stated, that no form of » is admis-
sible, which takes away the double sign placed before the
whole of the value of y.

Thus, if we take pw =ax+Vc* —(a x —x)’, we have
y= Fy +35Ve— (2 x —x)*5

but

t
y

OF LOCAL THEOREMS AND PORISMS. 347

but this does not satisfy the condition ns rendering the curve
symmetrical relative to its axis.

Let «x = Va? — x*, then we have

ye Ve—a? 2124V 07-4 gx
ox + e/a? — x? we t
and the following property belongs to all the curves contained
in this family :

Any curve BAC of this species being given, Fig. 7., a right line
BC given in length may be found such, that if it be any how pla-
ced, so that its extremities Band C coincide with any two points of
similar branches, but on opposite sides of the axis ; then the sum
of the squares described on the abscisse AK, AD, shall be equal
to the square described on a right line which may be found.

If we make « « =—.x, we have the family of curves ex-
pressed by the equation

‘pt Vert —4 x? 0x)
4 = Toxo (—2)
which possess the following property :

Any one of this class of curves being given, a right line CB may
be found, which, if it be placed so that its extremities rest on two
opposite branches of the curve (at C and B), and if the ordinate
at one of these points be prolonged on the other side the axis, un-
til the part produced (FE) be equal to the abscissa (GH) at the
other point, the extremity of the line so produced (FE), will be si-
tuated in a straight line given by position.

If we make 9x = 4, the equation becomes y = ae xe

and the curve is a circle whose radius is o the line to be

found

348 ON THE APPLICATION OF ANALYSIS TO THE DISCOVERY
found is equal to twice the radius, and the line given by posi-
tion passes through the centre, making an angle of s with the

axis.

ADE being any periodic curve of the second order, and
AF, AG any two corresponding abscissee, and ABC being any
other curve, whose equation is y= x, required the co-ordi-
nates of the point of intersection of its two tangents, at the
points B and C.

Call, AF =\x"; AG = xf
BF =7 CG=y;
and let x and y be the co-ordinates of any point in either of
the tangents, then

dy dy
Pera ag ay

dy aes
Y=* Fa =\gerine

are the equations of the tangents ; sal if we call v and w the
co-ordinates of the quel of intersection P, we have

i dogo Hit
pe eit § ST ee

And

Let

. = cs - ;
ee ol eS ee ee ee ee

—-

——

Ne ae

‘OF LOCAL’ THEOREMS‘ AND: PORISMS. 349

. Let us now suppose that the point Pis.always situated in the
sibhe line AL, perpendicular to the axis; we have v= 0, and
since the curve ADE is a periodic one whose equation is

YO K, r
of ee —jargttidter <
Whence $x— 504% = % {x, ax}
— - d ay Yea
e oa ea

from which yatra—x [Sy fz, ax}.
x

Now, let «x= (at — xa)a, the family of curves are com-
prehended in the equation

fae —«(G % Lx, (at — as} } ;
and they possess the following property :

Any of this species of curve being given, if any two abscisse
are taken, the sum of whose fourth “powers is equal to the fourth
power of a line, which may be found, then the tangent drawn at
the extremities of the ordinates corresponding to these abscisse,
will intersect each other @ an a line given,in position. This ste is
perpendicular, to the Axis. a

_ If we suppose’ ‘the point P: Sense to, be Aiaaeda in shat axis
Se the'absciss#, we have: w= 0, eT

"WOE dy ae: dy ACs 5 rit ca

or

350 ON THE APPLICATION OF ANALYSIS TO THE DISCOVERY
pu tbe* (px ee lesa Fee dtax
dax da oo Wass).

—1
multiplying both sides by a 2a dies ) we have
ax

d¥x\_ Fe a, ta
a) ee aa) — ak:

and since both sides are symmetrical relative to x and a x
’
we have

—1

d zee eR
yw my —x=y (x, ax),
d Bt te 2
or 9 ay tte 29);
dy dx

hence oon a =
; y x+y (x, wx)

a
If we suppose « x =(a"— x") *, the class of curves compre-

hended in the equation
dx

lo a Se
sy fF eee |
possess the following property :

Tf we take any two abscisse AD, AE, the sum of whose nth
powers is equal to a given nth power, then the tangents BP, CP,
drawn to the curve at the extremity of the ordinates correspond-
ing to those abscisse, will always intersect each other on the axis
of the abscisse. Fig. 10. :

In the same manner, a class of curves may be found, and

ordinates may be drawn, in such a manner, that the tangent
at

OF LOCAL THEOREMS AND PORISMS. » $351

at those ordinates shall intersect each other in a line given in
position.

In the curve ABC, hae any two ordinates, BE, CD, re-
quired its equation when the normals at these points intersect
each other on the axis; let x, y, and x, y, be the ordinates,

1 1

then we must have

AE + EP = AD + DP,

d ydy
or Pe eee t 4g

if the two points E and D are so chosen, that x= « x, and if

is a periodic function of the second order, we have, sup-

posing y=4ua
bx.d}x _ 4 tan ree
fret ee RO ed ee
.d 7 jute!
or ee te eas

hence ya —x42 fdey (x, ax)
If we make (x, ax) = x, we have
y=—x*+2cex+ec,

which is the equation to a circle, and it is well known, that
this curve possesses the property, since all its normals inter-
sect each other in the centre.

This furnishes us with the following local theorems. Any
curve of this family being given, if from any point (P), in the axis
of the abscisse, we draw two lines cutting the same branch of the
curve perpendicularly (in B and C), and if we prolong the ordi-

VOL. IX. P. II. yy nate

352 ON THE DISCOVERY OF LOCAL THEOREMS AND PORISMS.

nate (CD) at one of these points below the axis, until the part
below (DF) is equal to the abscissa corresponding to the other point
(AE), then the locus of the extremity of the ordinate (F) thus
produced, is always a periodic curve of the second order. Fig. 11.

The questions which we have now considered, appear to
me sufficient to point out the nature of that connection be-
tween the theory of functions and that of curves, which it was
my object to establish. The difference between the properties
thus brought to light, and those which have been hitherto
known, seems to consist chiefly in two points. The first is,
that the families of curves to which they relate are larger : this
arises from the arbitrary functions necessarily introduced into
the solution of functional equations. The other difference is,
that the properties discovered relate to many points of the
same curve, only connected by some given law. In the first
respect, they in some measure approach to the investigations of
M. Mones, in his excellent work L’ Application de P Analyse a
la Geometrie ; whilst, in the second respect, they bear some
analogy to the more general properties of curves, deduced
from the theory of equations in the Proprietates Curvarum of
Warrinc: these resemblances are, however, but superficial.
The nature of the questions we have considered requires, by
the usual methods of analysis, the application of mixed differ-
ences; and, in most of the few instances in which any such
problems have been proposed, they have been attempted by
that method. .

Devonshire Street, Portland Place, t
July 1. 1818.

XX,

f
x
0
tt
’

PLATE XXIII. Engraved tor the Roval Soo Huns Vol page

Bgl be WH Lazare

XXV. Observations on the Errors in the Sea-Rates of Chrono-
; meters, arising from the Magnetism of their Balances ;

with Suggestions for removing this source of Error.
By Wiu1aM Scorsssy, Ese. F. R. S. Enin.

~ (Read April 15. 1822.) =

NT tate

Tue value of the Chronometer for finding the Longitude at
Sea, being, by the experience of many years trial, fully esta-
blished, I am induced to offer to the Royal Society some re-
marks. on’ the change of rate observed in this instrument, when
_ on ship-board. This change of rate, that had usually been
supposed 'to arise from the motion of the ship, has recently
been‘attributed, by Mr Fisuzr, who accompanied Captain Bu-
cHan in his Voyage towards the North Pole in the year 1818,
“ to the magnetic action exerted. by the iron’in the ship upon
“ the inner rim of,the,Chronometer’s balance, which is com-
es posed. of steel.” I apprehend, however, that it will be very
easy \to show, that although: the alteration of rate may be, and
most probably.is, owing to magnetism, yet the magnetic ac-
tion of the ironin the ship, aadtption in cases where chrono-
meters are placed. in immediate contact with large masses of
iron, can contribute but in a very small degree to the error in

sitonaalt yy 2 question.

354 ON THE ERRORS OF CHRONOMETERS, ARISING

question. For, in the same proportion as the magnetism of
the earth, or the directive force on the compass-needle, ex-
ceeds the magnetism of the ship, or the deviating force, the
influence of terrestrial magnetism on the chronometer, must,
I conceive, exceed that influence exerted by the iron in the
ship on the chronometer. A modified action, indeed, takes
place where the direction of the magnetic force of the earth
differs from the direction of the “ local attraction” of the
‘“ ship ;” but yet the combined influences of the two forces,
however modified by direction, should, I imagine, be similar
on the balance of the chronometer, which vibrates in a hori-
zontal position, to what it is on the compass-needle, which tra-
verses in the same position.

Now, the medium effect of the attraction of the iron in ves-
sels on the compass, in the parallels of Great Britain, does not
appear to exceed five degrees of deviation on each side of the
magnetic meridian ; it is probably a little less. The force pro-
ducing the deviation, therefore, is represented by the sine of
the angle of deviation, or 5°; while the directive force is re-
presented by the sine of 85°. The relation of these two is as
1 to 11.35; that is, the directive influence of the earth’s mag-
netism on the compass is 113 times greater than the deviating
influence of the local attraction. Hence, the proportion of er-
ror due to the local attraction of the ship, would appear not to
exceed, in these latitudes, the eleventh or twelfth part of that
resulting from the earth’s magnetism ; while nearer the equa-
tor, this proportion of error must be still less. So long as the
action of terrestrial magnetism, therefore, remains uncorrected,
it will be of little service to compensate for the error arising
from the local attraction. In the Polar Seas, indeed, the force
of local attraction approaches the directive force much nearer
than in the British Seas, and in some situations very near the

Magnetic

a

e——————

i. ne i

FROM THE MAGNETISM OF THEIR BALANCES. 355

Magnetic Poles exceeds it; but still the local attraction ope-
rates without any increase of force, excepting what may arise
from the little augmentation of the magnetic intensity of the
earth in those regions ; so that, in reality, the rate of a Chro-
nometer in polar regions, where the earth’s magnetism acts
nearly at right angles to the plane of the balance, could the ef-
fect of temperature on the instrument be perfectly compen-
sated, ought to be more equable than in any other region,
where the direction of terrestrial magnetism is more nearly in
the plane in which the balance vibrates.

In the important and truly scientific experiments of Mr
Bartow, on the effects produced in the rates of Chronometers
by the proximity of masses of iron, we have a corroboration
of the preceding opinions; for Mr Bartow, though he obser-
ved that a variation of rate was occasioned by the influence of
a mass of iron equivalent to the local attraction of a ship,
found by no means so great effects as those observed by Mr
Fisuer. But the force of terrestrial magnetism acting upon a
balance that is magnetic, is fully sufficient to account for every
change of rate observed.

Mr S. Varxey, in a paper in Tilloch’s Philosophical Magazine,
published in the year 1798, was the first, I believe, who showed
that an irregularity observed in the rate of some time-pieces, was
owing to the magnetic state of their balances. He was direct-
ed to the inquiry by a watch of excellent workmanship that
he had in his possession, which performed the most irregular-
ly of any watch he had ever seen. It occurred to him that
the cause might be magnetism ; and, on examining the balance,
he found it so strongly magnetic, that when suspended hori-
zontally without the spring, it directed itself like a compass-
needle in a certain position, which it invariably returned to

when it was disturbed. The pendulum spring being put on,
and

356 ON THE ERRORS OF CHRONOMETERS, ARISING

and the balance replaced in the watch, Mr Varrey laid the
watch with the dial upward, and the north pole of the balance,
as determined by the previous experiment, towards the north ;
—in this situation it gained 5’ 35” in twenty-four hours. He
then directed the north pole of the balance towards the south,
every thing else being as before, and it now dost 6 48” in twen-
ty-four hours. Mr Variey afterwards took away the steel-
balance, and substituted one made of gold; then having
brought the watch to time, he carefully observed its rate, and
found it as uniform as. any watch of like construction. He
subsequently examined many dozens of balances, out of which
he. could not select one that had not polarity.

The instance observed by Mr Vartey is no doubt an ex-
treme one; but yet-the influence of magnetism in the balance
most probably affects the rate, in some degree, of almost every
watch and chronometer. I have attempted to ascertain how
far this influence might be considered as general, by experi-
ments both on detached balances, and on the rates of watches
under magnetic influence. Similar: experiments have been |
made by others ; but there were some circumstances neglect-
edin all; which I-was anxious to examine, particularly the
position of the watch or chronometer when its rate was deter-
mined... These experiments, owing to the arrival of the season
for undertaking my usual voyage to the Polar. Seas, I have
been unable to complete; but this much was accomplished:
In seven detached chronometer balances, very sensible mag-
netic properties, both attractive and. repulsive, were found in
all * ;.\and in three watches subjected to the action of magne-

tism,

* In some of these balances, the magnetism was strong. One, with three arms,
had a vigorous south pole at the extremity of each ray, and a common north pole
: at

FROM THE MAGNETISM OF THEIR BALANCES. 357

tism)a change of rate took place, whenever’ a change was made
in the relative position ‘of the watch’ and the magnet. Had
any of ‘the’ ‘balances! been free from’ magnetism, its rate, in’ all
horizontal positions, I expected, ‘would have ‘been’ tiniform,
whether ‘under the action’ of terréstrial, or of moderate ‘artificial
magnetism “For although iron acqitires ‘polarity,’ by mere
juxta-position' iio ‘a magnetised body, and the balances of |
watches placed near ‘magnets become: magnetic ; ‘yet, were the
magnetism ‘of the balance. only transient, ' thas ‘poles: ‘would
change with every” change ‘of “position | ‘in the‘ ‘watch, and ‘its
rate bike? ‘be unaffected ‘ by" any slight magnetic influence ;
but! were any of ‘the balances’ already permanently magne-
tic, there would ‘be a! repulsive’ action from’ the magnet in
some positions, and an attractive in others, which affecting the
vibrations of the’ balance in different ways, might be expected
to’ produce a change in the rate of the watch. ‘These effects,
it was presumed, would ‘be the’ same whether the watch were
tried in different positions, under the influence only of terres-
-trial magnetism, or under the action (directed in‘ a similar
way) of artificial magnetism ; the only siege pellet in the
quantity. Sib) 1
One of the watches under experiment was sabindl ays for
the beauty of the movement, and the uniformity of its rate.
I shall confine my athe rer aha to othe’ results obtained
Withtliiss? ee POM,
A bar. magnet, 12 inches long, was laid in the: magnetic
meridian, and the watch placed in the’ same line, four inches
distant from the magnet, with j its XM ) ‘clock mark towards the

Sa

a

= north.

lt PAA Tersisse 7 ia ir eas 7a
at the eentre. | THe-otlier ‘balances ‘liad generally ‘two poles: only but, in some,
the poles of the rim were not exactly coincident with the poles of the rays.

358 ON THE ERRORS OF CHRONOMETERS, ARISING

north. Its previous rate was in mean time; and it was set by,
and compared with, a chronometer, whose rate was very near-
ly the same. After an interval of 2 hours 18 minutes, it was
found to have lost 13 seconds, being at the rate of 135 seconds
per day ; the XII o’clock mark being now turned towards the
south, it gained 12 seconds in 2 hours 12 minutes, being at
the rate of 131 seconds per day. The position being again
reversed, it began to lose as in the first instance; but at a
rate somewhat less; and on being once more turned round,
with its XII o’clock mark towards the south, it gained 56
seconds in the course of the night, being at the rate of 156 se-
conds daily. This acceleration above its former rate was pro-
bably owing to the diminution of temperature. The regula-
rity of a change of rate, from losing to gaining, with each re-
version of position in the watch, every thing else being the
same, was a sufficient proof that some part of the watch was
magnetic, and that that part was acted upon by the influence
of the magnet.

Three means have occurred to me, of either lessening, or
altogether obviating, the anomalous action of the magnetism
of the balance, viz.

1. To employ a substance in the construction of the balance
without magnetical properties.

2. To free the balance of any magnetism accidentally ac-
quired.

3. To prevent the unequal action of the magnetic influence,
by giving to the chronometer a fixed position as re-
gards the magnetic meridian.

The first method, should there be no practical objection,

would go far towards the removal of all magnetic influence.
. The

ee

FROM THE MAGNETISM OF THEIR BALANCES. 359

The best material, in this case, to be substituted for steel,
would probably be platina, or an alloy of platina. As the ex-
pansion of platina with heat appears to be less than that of al-
most any other metal, being nearly one-third less than that of
steel, and less by above one-half than that of brass *, I should
imagine that it would be better suited for effecting the com-
pensation than steel.

For accomplishing the second object, I should emmad
that the flat surface of the balance be the last part. that is
finished, and that it be ground and polished in the plane of
the magnetic equator. » From various experiments with differ-
ent ferruginous substances, I found that no friction, however
severe, produced magnetism in flat plates or slender bars, when
the friction was endured in’ the plane of the magnetic equa-
tor; but that, on the contrary, such substances, especially iron
and soft steel, when hammered, bent, twisted, scowered, filed,
or polished in the plane of the magnetic equator, were depriv-
ed of any small quantity of magnetism that they might have
previously acquired +;' whereas by a treatment precisely. siz
milar, excepting as to position, ferruginous bodies were inva-
riably rendered magnetic. I have made some experiments on
chronometer balances, with the view of removing their polari-
ties; but although a- ‘sensible diminution of their magnetism
occurred ‘after grinding them in the plane of the magnetic
equator, or striking’ ‘them in the same plane with a small
smooth-faced: hammer, while resting upon a hard, flat'substance,
yet Ihave’ not had leisure to sare ei their neutralisation so
VOL. IX. PAIL ir een era eM BO TE ‘eet;

fer

; we . ‘Hear Ss Chemistry Table of Expansion of Solids by Heat.

ot See Transattions of the Royal Society of Edinburgh for 1821; “ Descrip-
« tion of a Magnetimeter,” &c. Propositions 4, 5, 6, 10, &e.

360 ON THE ERRORS OF CHRONOMETERS, ARISING

effectually as could be desired. As the balances are now ge-
nerally, I believe, wrought out of a solid piece of soft steel, en-
compassed by a rim of brass, it would conduce to the same
end if they could be turned in the plane of the magnetic equa-
tor; and still further, when dlued after polishing, if this pro-
cess were completed while the balances maintained the same
position.

But as a balance that has been freed from magnetism might
again acquire polarity, the third method I have to suggest
might probably prove the most efficacious, as regards steel-
balances and balance-springs, and it has the advantage of be-
ing applicable to all small chronometers. As its employment,
however, would be attended with some difficulties, I merely
throw out the hint at present, but with the hope of being en-
abled hereafter to determine the efficacy of the plan by expe-
riment.

A chronometer, even with a magnetic balance, may keep
very accurate time when on shore, and yet perform very ill at
sea. Because, while on shore, its position is usually preserved
unchanged : it is perhaps kept on a shelf or a bench ; in either
case it is not liable to be turned from its position, since the
lock of the box being commonly kept in front, naturally fixes
it invariably in the same way. But when the same chrono-
meter is taken to sea, its position is changed at the least every
time the course of the ship is altered; and with every change
of position there is probably an alteration of rate. Whenever
the north pole of the balance is directed towards the north,
the rate will (it is presumed from the experiments of Mr Var-
LEY) be accelerated; when towards the south, retarded.
Could, however, any method be adopted for giving a uniform
position to the chronometer, the errors arising from the above-
mentioned cause would no doubt cease. Something might be

done,

FROM THE MAGNETISM OF THEIR BALANCES. 361

done, by placing the chronometer, when on board, in the same
position that it occupied on shore, when its rate was taken, and
turning it whenever the ship’s course was changed. On board
vessels navigating in trade-winds, and in all voyages where a
steady course is preserved for a long time together, this would
not be difficult to accomplish; but as a good deal of trouble
would attend this management, in some voyages, it appears to
me that it would not be impracticable to fix a pocket chrono-
meter on the top of a thin plate of metal or wood, suspended
on a needle-point as a centre, and moved by a magnetised bar.
To diminish, as far as practicable, the influence of the magne-
tism of this bar over the chronometer, the plane for the sup-
port of the chronometer might be fixed a few inches above the
needle; and to prevent error from agitation, the apparatus
could be fixed on gimbles like a compass.

It may be objected, that the influence of the magnetic bar,
connected with the apparatus for carrying the chronometer,
would induce magnetism in the balance, notwithstanding it
might be at some inches distance, and thus augment the source
of error. 1 apprehend, however, that as the bar is proposed to
be placed beneath the chronometer, so that its action would
be almost vertical to the plane in which the balance vibrates,
very little, if any effect, would be produced on the rate of the
instrument. Besides, were the rate of the chronometer taken
on shore when fixed in a certain position on this apparatus,
there would be every chance of its maintaining its rate at sea,
while the dip was nearly the same; for the action of terrestrial
magnetism, combined with that of the local attraction of the
ship, would produce a mean action on the bar carrying the
chronometer, and a similar action on the chronometer. Un-
der great changes, indeed, in the magnetic intensity or dip, a
chronometer even thus situated might be liable to a small va-

zz 2 riation

362 ON THE ERRORS OF CHRONOMETERS, &c.

riation in its rate ; but were the rate of the chronometer taken
in various positions in the apparatus, and the position where
its rate was nearest a mean given to it for its permanent posi-
tion, then, I imagine, its rate would be uniform under all
magnetic dips, and under all ordinary changes of intensity.

APPEN-.

(363°)

VAPPEN DIX. 1 0°
Since forwarding my communication to the Royal. Society,
“ On the Errors in the Sea-Rates of Chronometers, arising
“ from the Magnetism of their Balances,” &c. I have con-
structed a temporary apparatus on the principle described i in
the third “ suggestion for removing this source of error.” I
was at first doubtful whether a’ plate, however light, when
loaded with the weight of a pocket chronometer, could be
made’ to traverse by the polarity only of a compass-needle ;
and whether, within a moderate compass, the magnet intended
for directing the plate could be so far removed ‘from the chro-
nometer as ‘to etal all fear of’ ein mischief from its

proximity. avers
“On trial, ‘¥ ‘was happy to find my dbf hrceiatike respecting
the interference of both these apparent difficulties éntitely re-
moved. For, by means of a compass-needle, indifferently
magnetised, the plate for the chronometer traversed, when
loaded with a pound weight avoirdupois ; and the magnetic in-
fluence of this needle, at five inches distance: (the distance be-
tween the chronometer plate and the needle) was only equal
to the directive force of the earth on a horizontal needle in
Britain. Now, such a degree of influence would probably be
an advantage to the chronometer’s going rather than other-
wise ; because the denomination of magnetism in either end
of the needle, operating on the part of the chronometer to
to that’of the earth operating on the same part of the chrono-
meter ; hence the tendency of the magnetism of the needle on
the

364 APPENDIX.

the chronometer (being the opposite of that of the earth, and
nearly equivalent in intensity), would be to neutralise the ef-
fect of the magnetism of the earth on the chronometer.

The apparatus I propose for giving uniformity of position :
to chronometers at sea, so as to obviate the varying action of
the magnetism of the earth on magnetic balances in different
positions, is represented in Plate XXIII., where’

A, Is a compass-card (without a needle), having a light slip
of brass across the under side, and an agate cap in the
centre, for carrying the chronometer B.

C, A centre of brass pointed with steel, of a needle temper,
upon which the card and chronometer traverse.

D, A magnetic rhomboidal compass-needle, on Captain Ka-
TER’s construction, adopted in consequence of its great
directive force. This needle is suspended from the
card by 4 or 6 small wires (a, a), which serve to keep
the card horizontal, and cause it to traverse.

EE, A cylinder of thin copper or brass; to the bottom of
which is fixed the centre C, which passes through the
opening in the middle of the rhomboidal needle.

FF, The centres by which the apparatus is attached to
gimbles i in the usual form.

The whole is enclosed in a square wooden box, with both a
glass and a wooden lid.

The chronometer being placed in the centre of the card,
and adjusted with its XII o’clock mark always in one direction,
will evidently maintain the same position so long as the card
continues to traverse.

XXVI

XXVI.—Report on a Communication from Dr Dyce of Aber-
deen, to the Royal Society of Edinburgh, “ On Uterine Ir-
ritation, and its Effects on the Female Constitution.” By
H. Dewar, M. D. F. BR. S. Enrn..

(Read February 18. 1822.)

Tue communication received from Dr Dyce chiefly con-
sists of a description of a singular affection of the nervous sys-
tem, and mental powers, to which a girl of sixteen was sub-
ject immediately before puberty, and which disappeared when
that state was fully established. It exemplifies the powerful
influence of the state of the uterus on the mental faculties ;
but its chief value arises from some curious relations which it
presents to the phenomena of mind, and which claim the at-
tention of the practical metaphysician. The mental symptoms
of this affection are among the number of those which are con-
‘sidered as uncommonly difficult of explanation. It is a case

_ of mental disease, attended with some advantageous manifes-

_ tations of the intellectual powers ; and these manifestations dis-
_ appearing in the same individual in the healthy state. It is an
instance of a ‘phenomenon which is sometimes called double
consciousness, but is more properly a divided consciousness,
or double personality; exhibiting in some measure two se-
os parate

366 ON UTERINE IRRITATION, AND ITS EFFECTS

parate and independent trains of thought, and two indepen-
dent mental capabilities, in the same individual; each train
of thought, and each capability, being wholly dissevered from
the other, and the two states in which they respectively pre-
dominate subject to frequent interchanges and alternations.

The particulars will be most agreeably communicated, in the
order of their occurrence which is followed by Dr Dycr,—
part of the narrative being given in the words of Mrs L ;
in whose house the patient lived as a servant, and the rest in
the words of Dr Dyce himself, consisting of the facts which
fell under his own observation.

The history of the complaint, while under the eye of this
gentleman, extends from the 2d of March 1815, to the 11th of
the following June, including a period of more than three
months. But the symptoms had made their appearance in the
end of the preceding December. :

The first symptom was an uncommon propensity to fall
asleep in the evenings, for which she was reproved by. Mrs
L—.. This was followed by the habit of talking in her sleep
on these occasions. She not only uttered such wild inco-
herent expressions as persons, under the affection of sleep-talk-
ing commonly do, but repeated the occurrences of. the day.
She also sang musical airs, both sacred and profane.) --

One evening, in the house of an acquaintance of Mrs L—=,
where she seems to have come for the purpose of seeing her
mistress home; she fell asleep in this manner; imagined herself
an Episcopal clergyman, went through: the ceremony of bap-
tizing three! children, and ;gave an» appropriate | eatempore
prayer. -Her mistress: shook ‘her by :the: shoulders, on: which
she awoke, and appeared: inconscious°of every thing except
that she had fallen‘asleep, of which'she shewed herself asham~
ed. OW) OTBenONT om anitidimize ,witlonosig oléweb 40

lars : Another

Oe

ON THE FEMALE CONSTITUTION. 367

Another evening, having fallen asleep surrounded by some
‘of the inhabitants of the house, she imagined herself to be liv-
ing with her aunt at Epsom, and going to the races; placed
herself on one of the kitchen stools, and rode upon it into the
room, with much spirit, and a clattering noise, but without be-
ing wakened. Being afterwards severely reprimanded for
this exhibition, she continued free from the habit for a week.
After that interval, however, it returned in a similar form,
with this addition, that, when in this state, she answered ques-
tions which were put to her by others. The disease now in-
creased, and came on her at different times of the evening and
morning. She sometimes dressed herself and the children
while in this state, or, as Mrs L calls it, “ dead asleep,”
answered questions put to her in such a manner as to shew
that “she understood the question; but the answers were
often, though not always, incongruous. One day, when she
was in this state, her fellow-servant was desired to get the
key of a closet from her, in order to do the duty which was
generally hers, that of setting the breakfast-table. The girl,
however, refused to give up the key, and set the breakfast
herself with perfect correctness, with her eyes shut. She
afterwards woke with the child on her knee, and wondered
how she had got on her clothes. If seized in this manner in
the house, she was sometimes restored to her senses by being
taken out to the cold air, especially when the wind blew in
her face. At other times she was seized with this affection
while walking out with the children.

In the mean time, a still more singular and interesting
symptom began to make its appearance. The circumstances
which occurred during the paroxysm were completely forgot-
ten by her when the paroxysm was over, but were perfectly
remembered during subsequent paroxysms. Her mistress

VOL. IX. P. II. SA says,

368 ON UTERINE IRRITATION, AND ITS EFFECTS

says, that, when in this ‘stupor on subsequent occasions, she
told her what was said to her on the evening on which she
baptized the children. It was remarked that, while ‘under
the paroxysm, she knew a person’ better: ‘by! looking at the
shadow than at the body ; that is, she perceived those ‘objects
‘best which were presented merely in outline, or were very’ dim-
ly illuminated. The disease made progress in the interval be-
tween its first appearance in December and the beginning of
March, though no dates of its different stages are given.
From the 2d of March till its disappearance Dr Dyce’s ac-
count is very circumstantial.

She was brought to him for medical‘advice by her’ mother.
The mother called these‘affections sleepy fits. ‘The girl herself
called them wanderings. They sometimes continued for an
hour. If they came on when she was in bed, she sometimes
rose and tried to raise the sashes of the windows. The eyes
were described as half-shut, the pupils dilated, and the cornea
covered with a dimness or glaze, resembling those of a person
in syncope. She answered many questions correctly, shewing
at times scarcely any failure of her mental powers. It was re-
marked, that she always retained ee a He ee on
her previous to the fit.

With regard to the case as an atu of medical attention, it
is sufficient to mention that some ee of pouate, ‘and

wae) iQh a 217)

to their degree. aa ac: OF ORY
The symptoms of the paroxysm, dg ee fell undér the ‘Dod:
tor’s own eye for the first time, are ‘thus ‘desctibed,* “ When

she was brought to my room she’ appeared as if i in a‘ staté of
‘sttipor,

a es

a i re 7 ae

i « “we

ON THE FEMALE CONSTITUTION, 369

stupor. Her eyes were half-open; but, when desired, she
could open them completely. At. other times she closed them,
as if inconscious of what.she did. When desired to look at
me, and tell who I was, she gave a vacant kind of stare, and
named some other person.. When desired to look round, and
say where she was, she looked round with some apparent at- -

* tention ; but, though she had been in. that room more than:

once before, she said she was in the New Inn. | When de-
sired. to turn her eyes to the direct rays of |the sun, she readily
obeyed, but, there was,.no perceptible contraction of the iris.
She saw some objects perfectly, for, she read quite distinctly a
part of the dedication of a book which she could not, have seen
before, and corrected herself in the pronunciation jof| the word
conspicuous, which she had. called conspicious.. Being asked to tell
the hour by a watch) which: ‘was shewn to her, she did not give
the proper/answer. Pulse 70; extremities rather cold... Be-
ing desired to stand up, she, did it,most, readily, but, required
some time and a little effort to stand firmly, as she staggered
at first. like a person waked out of sleep. But. soon after, she
could stand, walk, or dance as well as other people. Being de-
sired to sing, she sang a a. hymn, delightfully ; 3 and from a com-
parison which I (Dr Dyce) had an opportunity , of making, it
appeared incomparably_ better sung than she could sing the
same tune, when well, , The same, ‘appeared to. be the case to
persons whose skill in, music ‘was much superior, to my own.”
Her hands were immersed i in cold. water, in _ consequence | of
me ‘she ecoyered Li Senses, m RELY, like : a person waked

i938

ee where she lived, and, was yh now. at ies suggestion of
the person 3 who » accompanied: her. ‘She now sa the persons

and things surrounding Lis sromi’ ¢ pools fowlew eotiysisas
a@ The

370 ON UTERINE IRRITATION, AND ITS EFFECTS

The account which she gave of her feelings as connected
with her present situation was, that previously to an attack she
felt drowsy, with a little pain in the head; then a cloudiness
or mistiness came over her eyes; she heard a peculiar noise
in her head resembling that of a carriage running, and had a
' feeling of motion as if she were seated in such a carriage.
When this stage supervened, her conceptions of external ob-
jects were immediately altered.

Next day (March 5.) while under a fit, she performed in
the most correct manner some of her accustomed duties relat-
ing to the pantry, and the dinner-table. Dr Dycz went to see
her; she gave him a wrong name as formerly ; when her
mistress desired her to stand straight up, look round, and tell
where she was, she recovered instantly; but it was only for a
little ; she very soon relapsed. When asked to read in an al-
manac held before her, she did not seem to see it, nor did she
notice a stick which was held out to her. Being asked a se-
cond time to read, she repeated a portion of Scripture, and
did not give a correct answer when asked where she was. Be-
ing desired to state what she felt, she put her hand to her fore-
head, and complained of her head ; said “ she saw the mice run-
ning through the room.” Mrs L—— mentioned that she had
said the same thing on many former occasions, even when her
eyes were shut ; that she also frequently imagined that she was
accompanied by a little black dog, which she could not get rid
of ; did not, in general, express any particular uneasiness from
that cause ; at times, however, cried in consequence of it, and
at other times laughed immoderately. In some of her repeat-
ed paroxysms, she insisted that she was going to church to
preach. One day, while taking out two infants for an airing,
she was seized with one of her fits on the quay, and without
hesitation walked along a single plank placed between a ves-

sel

ON THE FEMALE CONSTITUTION. 371

sel and the shore, and even danced on it with the children.
Of this circumstance she afterwards, when well, denied all
knowledge. This was invariably the case ; but with equal re-
gularity she acknowledged and asserted it when under the in-
fluence of a paroxysm. —

On the following day she had a threatening, which went off
without being followed by the usual degree of insensibility.
She says she now knows for a quarter of an hour before the
attack. This day some local bodily symptoms were added to
her usual complaint, which it is unnecessary to particularise,
but which were fully accounted for by a horrid transaction
which on the following day (the 8th of March), her mother
related to Dr Dycz. Another young woman, a depraved fel-
low-servant, understanding that she wholly forgot every tran-
saction that occurred during the fit, clandestinely introduced
a young man into the house, who treated her with the utmost
_tudeness, while her fellow-servant stopped her mouth with the
bed-clothes, and otherwise overpowered a vigorous resistance
which was made by her even during the influence of her com-
plaint. Next day she had not the slightest recollection even of
that transaction, nor did any person interested in her welfare
know of it for several days, till she was in one of her pa-
roxysms, when she related the whole facts to her mother.
Some particulars are given by Dr Dyce clothed in the Latin
language, and others were told him which he does not think
it necessary at all to detail.

Next Sunday she was taken to church by her mistress, while
‘the paroxysm was on her. She shed tears during the sermon,
particularly during an account given of the execution of three
young men at Edinburgh, who had described in their dying de-
‘clarations the dangerous steps with which their career of vice
and infamy took its commencement. When she returned home,
Mans she

372 ON UTERINE IRRITATION, AND ITS EFFECTS

she recovered in a quarter of an hour, was quite amazed at the
questions. put to her about the church and the sermon, and de-
nied that she had been in any such, place ;, but next night, on
being taken. ill, she mentioned. that she had been at church,
repeated the words of the text, and, in Dr Dycer’s hearing,
gave an accurate account of the tragical narrative of the three
young, men, by. which her, feelings had. been so powerfully
affected. On, this occasion, though i in Mrs Lonrsi s pages she
asserted that she was in her mother’ ‘. sthoe woh eis

Dr Dyce saw her on many sulisehent occasions, when simi-
larly affected, and from one fit; she recovered in his| presence.
He said.the eyes had now all, the vivacity of youth and health.
Previously they were like,those of a, person under amaurosis,
or. those of a. person half-inebriated, and who, had ;neyer been
in that state before. The ‘difference, he says, is not perfectly
expressed by either or.both of these comparisons, but was, POM
striking to all, who saw, hem jagvron-wollet red «

Calling one. day, an hour, after recovering joe. A fit ‘ith
which she had been seized in the, morning, she was quite well,
‘only complaining of a).confused :feeling inher, head,;:accompa-
nied now. and then with ringing of the/ears.: The. countenance
was somewhat ae and |there:was:a aeat lividity under
the eyes.ixi) os ajoy dw ant hada ion Amis EK

On one.occasion, whet the Doctors saw np ina fit, hesays
he stare was accompanied with. something ebay a) ial
in the eye. bee

About. the 26th of March she: casas halk Hee in ther
head, as if it-had been ‘cut: in two. dalalabcatidh eas bad, only
complained of confusion. 1.0) 9 J1ie 8 gatih yusluaisiad

On) Sunday the 26th, while.in;: ia, fit, she commenced :prepa-
witions fox going to church j.buty while curling her: haix, burned
her brow with the. hot, curling-tongs, which roused: her from

the

a See

°° ON “THE FEMALE CONSTITUTION. . 393

the torpid state, and she immediately recollected that her’ mis-
tress\had given her orders to'stay at home. ©

On Friday the 7th of April, Dr Dyce had’an. opportunity of
seeing her under'the influence of a fit, in her mistress’s house.
He found her running up and down the room, arid arranging
things which’ appeared to her to ‘be in’ confusion. “On ‘being
asked if she laiew him, she: sai ‘Oh’ yes, I know’ that stick
and tassel ; they are’ Dr Dyce’s.” Her eyelids appeared shut ;
but when’ ihe stooped; and looked to'them: from below, he
found them not entirely closed. When he raised'the' upper
eyelid a little, it seemed to give her pain, at’ least'she would not
allow it to be repeated. When he desired her to point to differ-
ent parts of his body and dress, and name them, he found that
she could not do'it when the light of the candle or fire shone
fully on him ; but pointed out every part accurately, when it
was placed in the shade. At this time, when he tried again to
open the eyelids, he found the pupils greatly contracted, a
state the reverse of that which made its appearance in all his
previous examinations: This contrariety is not easily explain-
ed when'we- consider ‘that’ the’habitudes ‘of ‘the’ function of vi-
sion seemed in all other-respects" padi as ‘on niger ag
sronserog sledsdismor yisy « Hoeti of ei evcilodarsnaic

On examining her’ headialeovsie Deed now este par-

“ticularly; thatishe' bhiumk much when lie touched the upper part,

the resion of the fontanélle;-: The head‘was'shaved, with a view
tocthe applieationvof lablistér; ald ‘he ‘found some ‘degrée of
swelling: inithatsituation The sorenéss: wasentirely superfi-
dial {forailight: itouch ogave theostme’ p pailr as’ elites flere
or'eonsidlereble: oprassures: i dada bar ano adt 2 Ig ac
oi FyomMfonday the?! 7th’ of! April, ill’) Friday the. od of May,
she ‘was free! from''anyparoxysmi begrgne nod etn fnvbivih
O: Tn “eonsequeice: of “the ji kecettna of ‘bloédy stools, and

other a ss of a’ similar ‘nature, Dr Dyce thought proper
to

374 ON UTERINE IRRITATION, AND ITS EFFECTS

to have her bled. An emetic was exhibited, and brought up
from the stomach a black matter, appearing to consist partly
of old and darkened blood.

On the 18th of June she felt a little fulness and uneasiness
in her breasts.

On the evening of the 11th there was a slight appearance of
the menstrual discharge, which disappeared next day.

On the 15th the same appearance occurred.

The menses appeared regularly on the 9th of July and the
5th of August.

Ever after the first appearance of this discharge she conti-
nued free from complaint, up to the time when Dr Dycr’s ac-
count closes, when he had just seen his quondam patient more
than a year after she had been perfectly well.

Tuts case certainly gives an interesting illustration of the
obliquities to which the physiology of the nerves, and the ex-
ercise of the mental powers are subject.

Somnambulism is in itself a very remarkable phenomenon,
not so much from the partiality of the affection of the senses
implied in it, for this is sufficiently exemplified in the act of
dreaming, in which the imagination alone is active, and is not
guided, and but very obscurely influenced, by any of the objects
which solicit the external senses. It is well known, however,
to those who have studied the history of dreams, that this is
not always the case, and that in many instances the manner
of dreaming is dictated not only by the scenes in which the in-
dividual has been engaged when awake, but by those objects
which are at the time presented to his senses, especially to
those of touch and hearing. The most remarkable circum-

stance

OI a a

ON THE FEMALE CONSTITUTION. 375

stance in somnambulism, is the unequalled accuracy. with
which a person in that state sometimes conducts his proceed-
ings, an accuracy superior to that of which he is capable when
fully awake. A somnambulist has gone out by a window, and
walked along the roof of a house, with a degree of’ security
which he never could have enjoyed in the same local situation
in his waking hours. Such facts evince a strange mixture of
accurate perception and self-management with the absence of
general recollection and self-knowledge: and it is remarkable
that the accurate’ perceptioris which’ persons in. this situation
retain, and which may in some measure be the effect of habit
on the faculties, are so completely dissevered from the imme-
diate influence of general sensation, that when the individual
is wakened by loud speaking, or by a shock from a by-stander,
he sometimes becomes inexpressibly bewildered and unhappy;
and does not know where he is. Instances.are said to have oc-
curred, in which a somnambulist abruptly wakened while, walk-
ing out of doors, has, by the unhappy distraction attending
the transition, been thrown into a state of permanent insanity.

The influence of association on all our thoughts, on the me-
mory, on the imagination, and even on the freedom and facili-
ty of those mental movements which we call exertions of the
active powers, is familiarly observed by every person who has
paid the least attention to human nature, or to the proceedings
of his own mind. We never wonder at our mental acts being
varied in their degree of intensity or facility by this all-per-
vading principle. It is only a greater degree of the same de-
pendence on particular associations that constitutes such ano-
malies as made their appearance in the history of this poor
girl. In other cases, objects are recollected less easily and
less vividly in some circumstances than in others. In this case
one set of objects was not recollected at all, and could not be

VOL, IX. P. II. 3B in

376 ON UTERINE IRRITATION, AND ITS EEFECTS

in' the least degree recognised or brought to mind by any sug-
gested associations, unless they occurred in that train, and
while the mind was under that particular diseased habit: under
which they were generated; and in this. case they occurred
with readiness and fidelity. :

This, indeed, was: a‘ case of disease, evidently depending on
the state of the brain as connected with the habitudes of the
sanguiferous system. In this particular it is to be ranked with
the aberrations which constitute many cases of insanity ; and it
is both curious and humbling to think, that in insanity itself there
is scarcely’a mental irregularity admitting of description, but
what may be shown to be only a greater degree of those
mental aberrations, those follies, and those partialities to which
the most vigorous. and the most correct minds are erent!
liable * gD} .
The shtvorhs contrast between the mental states of this per-

son under’ her fit; and when it was off, is to be classed with a
set of facts, of which some other examples have lately come to
the public: knowledge.» One of them was in an apparently
simple girl in the neighbourhood of Stirling, who, in her sleep,
talked like a profound philosopher, solved geographical pro-
blems, and enlarged on the principles of astronomy, detailing
the workings of ideas which had been suggested to her mind,
by over-hearing the lessons which were given by a tutor to the

children of the family in which she lived. The originality of

the language which she used, shewed something more than a
bare repetition of what she had heard. She explained the al-
ternations of winter and summer, for instance, by saying, that
“ the earth was set a-gee.”

Another
BOOM OL eso it resi Boa ea lannyeie Samos! itt yD vivieas

* Some views on this subject are given by the author of the present report in
the article “ Insanity,” in the Edinburgh Encyclopedia,

—_— ee

ON THE FEMALE CONSTITUTION: . 377

Another case was mentioned in some of the: newspapers,
two or perhaps three years ago, of a more, marked instance of
double consciousness. The individual was liable to two states,
each of which, if I rightly recollect, continued for two or more
years. In the one state, when it first came on, there was an
oblivion of al] former education, but no deficiency of :mental
vigour as applied to ideas or pursuits subsequently presenting
themselves. It was necessary for this woman to recommence
the studies of reading and the art of writing: A:separate set of
notions, and separate accomplishments were now formed. In
one of the states an exquisite talent for music, and some others
which implied refinement, were displayed... When another
mental revolution arrived, these utterly disappeared, and the in-
dividual was reduced to a level with the rest of mankind, dis-
playing a sufficient portion of common seltig but: nothing
brilliant. mint

Differences more or less allied to these are seems by a
variety of causes. . inlwe

Sometimes. external uti has! an infliénde of ‘this kind.
There are’ individuals who, in the:‘hour of, prosperity, and
when under the influence of sober, and uniform gratifica-
tion, show an exquisite taste for music, but lose this as soon
as a slight cloud appears on the horizon of life, and who then,
though they ‘evince such talents as are the result of persever-
ing thought, and. are capable of being exercised by: deliberate
study, lose all that satisfactory delight which gives birth to a
brillianey of mental manifestations ; at least these only appear
in the occasional occurrence of happy combinations, being
never, for any length of time, animated by such a supported
impulse as to generate a current of habitual felicities.

Sometimes the state of the brain, as influenced primarily
by disease, determines ‘the operation of these mental states. .

3B 2 - External

378 ON UTERINE IRRITATION, AND ITS EFFECTS

External applications are well known to possess a similar
agency. We all know the influence of opium, and still more
familiarly that of inebriating liquors.

A more singular agent is the gas called the nitrous oxide,
when inspired by the lungs, by the use of which the individual
is elevated in half a minute to the third heavens, and when
it is discontinued, is in an instant reduced again to the feelings
of a common child of earth.

The girl who is the subject of Dr Dycr’s communication
made, in the mode of commencement of her paroxysm, an ap-
proach to what is frequently the effect of this curious agent.
Some persons (perhaps the greater number) who breathe the
gas first feel a little confusion, afterwards a tingling in the
ears, then a sensation of great fulness and tension of the cra-
nium, giving the idea of a bladder distended with air. This
is accompanied with a feeling of alarm, but is instantly follow-
ed by a train of rapturous thoughts, accompanied by a feeling
of mental power, during which thousands of ideas seem to pass
through the mind in a small fraction of a minute, and the in-
dividual feels as if nothing in the universe could resist his
energies. The commencement of this state has some resem-
blance to that of this girl, as above described; she said that
she first felt a drowsiness, with a little pain in the head ; then
a cloud or mist came over her eyes, attended with a peculiar
noise and motion in the head, resembling a carriage in which
she was placed, moving along with great velocity. The re-
semblance is not perfect. It is only such as to shew some
analogy between the effects of the nitrous oxide and the state
induced by a paroxysm of disease arising from particular
spontaneous circumstances of the constitution, and accompa-
nied by a sufficient susceptibility to tender emotions, and the
exhibition of more than her ordinary degree of musical taste

and execution.
Tue

OE

_——_

ON THE FEMALE CONSTITUTION. 379

Tue preceding analogies are, I confess, somewhat loose. It
would be interesting to have a copious collection of well au-
thenticated facts, and an arrangement given to them fitted to
shew the shades of transition by which different mental states

graduate into one another.
H. Dewar.

XXVII.

‘ wag! > *

fr

De ad oo at Mr,

.

tan
=H
~ot bat: 1 ashe.
‘ ~ abr eal he, Syste pies,
4 Rey om teed eyed
bi “ rote vigil hh v9 Lt grat
Barty eb cers
F aes e alt
opel wagon ~ Kos do ys
apap ev paca ;
* ‘ebatt 1 is gener:
wid P f
Pry ay
x ie fh

4 Foot 10 Inches

7 Inches

+S Foot

PLATE XXIv. Bing ter the Rept Sua Tran? Vat LN page 382
INDIAN IDOLS.

OF TALCACEOVS STONE

BUDA.

J Foot 6 Inches

~_
the Inscription which is in the nimbus behind the head of Tuda

Part of the Inse:

ii
“yf
it

ells
if im
ell

"
i

SORTA, THE SEN .

a 19170) Yor] ,2cr Ode ee ai
‘ “ a; D bs tt we
, e Indian an Idols in the useum of the

» |

» CADELL, Esq. FVR.S. Lond. &

"(Read March 6. 1820.)

NS Rd

Laem , by Francis Simpson, hae nen I
pr Sake to the Apclety at hi iis

ae the ee a aa ae

. fig. ae “4 the god-

our ing Time, like
( the destroy- 1
Egyptian | mytholo- or ei
si idering the A ontinual recurrence } Bie oxie

ee

is and Dekic ee ‘regular pheno- aaa t “atk
8 i 3 Nature which are beneficial to man-— y
fore myri-onymos, s she had a a multitude of — ({ Ne

fe fying water of the = the Sun, » the m opine

5 hod t

382 DESCRIPTION OF SOME INDIAN IDOLS

Earth, Heaven ; she was worshipped as the giver of all that is
good and beautiful in nature. They imagined another deity,
Typhon, the destroying power, the cause of miasma, of exces-
sive heat, of storms, of every inordinate action of the ele-
ments, whether in excess or defect, and whatever is hurtful to
mankind *. In like manner, amongst the Hindus, Vishnu,
(that is the pervader), the preserver and giver of life, is a per-
sonification of the power of the Supreme Being, which is ex-
erted in preserving the universe. Siva represents the Supreme
Being, considered as the destroyer and changer of forms; and
Bramah represents the creating power of the Supreme Being.
The goddess Cali is the consort of Siva; she is represented in
the figure before us as an emaciated old woman, with a hide-
ous countenance, and pendulous breasts. The eye-balls appear
like hemispheres in the sockets, by reason of the atrophy of
the fat and muscle. The figure has many hands, holding wea-
pons of different kinds; a sword, a sacrificing knife, a mace,
a bell that announces the sacrifice, a rattle called damaru,
shaped like an hour-glass, and a human head. The right
hand in front holds a cup of the blood of sacrifices; a fin-
ger of the left is placed on the lips. The sole of the left
foot is turned upwards, and a round body like a coin is placed
on it. Human skulls are in the head-dress, which is sur-
mounted by a bird like an owl; snakes hang down from the
head, on each side, in place of hair. A cord on which human
skulls are strung, called mund mala, (that is, chaplet of
skulls), hangs down over the shoulders. The skulls repre-
sent the lapse of ages, by the extinction of successive ge-
nerations. Cali is seated on the prostrate figure of a man,
typical of the destruction of the world, and of secular time,

which

* Plutarchus de Iside et Osiride:

Se ee ee ee

IN THE MUSEUM OF THE SOCIETY. 383

which is trodden under foot by Maha Cali or eternity *,
A small figure of an antelope or kid standing, and look-
ing up, is on the left side of the stone, near the head
of the prostrate figure: this is not seen in the drawing,
which represents only the front of the stone. Cali is paint-
ed black by the Hindu artists. Anciently human sacrifices
were offered to Cali, according to the ritual of the Vedas;
the sacrifices now offered are kids. The worship of Cali ori-
ginated in India, with the Saiva’s, that is, the sect of Siva,
and caused a separation from the Vaishnava’s or sect of Vish-
nu. The consort of Siva, like the other deities, is known by
many different epithets, with some variation of character and
attributes in each form and name; she is Cali, Parvati, Darga,
Bhavani. The Cali age, or Kolei joog, in Hindu mythology,
is the fourth age of the world, the age which now exists: the
epoch of the commencement of this era is 4916 years ago.

In the possession of the Antiquarian Society of Edinburgh,
there is an Indian idol of stone, representing a man standing,
with four arms holding weapons, and a cord hanging down
from the arms, like the figure of Cali at Fig. 1: but the ex-
pression is quite different, the figure is not emaciated, the face
is placid, and there are no skulls on the cord. The god
Cal, a god of the sect of Siva, is represented with similar em-
blems in the excavated temples of Elephanta. Vishnu is also
represented with four arms, holding the flower of the nelum-
bo; the sancha, an emblem of his power to preserve; the
mace, a type of his destroying power ; the chacra, shewing his
universal supremacy.

Another figure of this kind, with four arms, holding a mace
and other weapons, and standing upon a lion, is in the Mu-

VOL. IX. P. Il. 3c seum

* See Asiatic Researches, vol. viii. Dissertation 3.

384 DESCRIPTION OF SOME INDIAN IDOLS

seum of the University of Edinburgh: it is Cali in one of
her characters called Darga, (that is, difficult of access), attend-
ed by Siva, in form of a lion; the figure is of talcaceous
stone. The Hindu god Iswara, a name which Sir W. Jones
supposes to be analogous to Osiris; the goddess Isani, who re-
presents the powers of nature; Carticeya, the son of the god-
dess Parvati, (parvat signifies mountain) ; these three (Iswara,
Isani, and Carticeya) are deities of the sect of Siva, like Cali,
and are represented like Cali with many arms holding wea-
pons. The god Quanwon, worshipped in Japan, is repre-
sented in the same manner *.

The next figure (Pl. XXIV. fig. 2.) is Supra, the Sun, the
deity whose province is analogous to that of Apollo in the
Greek mythology. -The three great Hindu divisions of the
power of the Supreme Being, are Vishnu the preserver
and giver of life, who is also: called Narayan, (that is,
moving on the waters); Siva the destroyer, reproducer,
and changer of forms, called also. Mahadeva: and Brahma, the
Creator. Suria is the image of a portion of the first of these
powers. Etymologists have shewn. the resemblance of the San-
scrit to the Persian, the Greek, Latin, and Gothic languages ;
so as to make it probable that the nations of Europe, the Per-
sians. and. the Hindus, derive their language and birth from
one and: the same. ancient nation which existed in Persia be-
fore the Assyrians, and before the times recorded in the his-
tories now extant. An instance of this resemblance occurs
in the Hindu word Suria, and the Greek Yess, which appear
to originate from the same root, signifying in both languages
a brilliant star and the Sun. Suidas and Hesychius mention
that the words Zee and Zeiss, in the languages anciently

spoken

* See a figure in Kaempfer’s History of Japan.

IN THE MUSEUM OF THE SOCIETY: 385

spoken on the eastern shores of the Mediterranean, were ap-
plied to denote the Sun as well as the star Sirius, which is
one of the most brilliant of the fixed stars visible in the cli-
mate of the Mediterranean. Crishna is another name given
by the Hindus to the idol that they have formed as a per-
sonification of the Sun. Crishna, the shepherd god, is also
considered to be an incarnation of Vishnu, and his life upon
earth is related in Hindu books: in a celebrated temple
in India, Crishna is worshipped under the. name of JTa-
gan-nath, that is, the lord of nature. The figure of Suria is
here erect. The principal figure, and three of the at-
tendants, are placed upon bases, formed like the flower
of the nelumbo or. water-lily, and flowers are represented:
on each side, indicating the power of the sun in promoting
the vegetation of plants on the earth.. The hands of the figure
are broken off, but there remains an octopetalous flower, which
was held in the left hand. By the side of the figure of Suria
are three smaller figures, in the same dress..as the principal
figure, with the hands clasped in the attitude of adoration:
they are called the gopis or shepherdesses; one of them
has four arms. Four small figures, seated with the legs across,
are in the upper part of the composition, and a figure seated
with the legs across is in the head-dress of Suria. The
head-dress is formed of several tiers of ornaments, somewhat
in form of crescents, or like the two horns ofa chamois. At
the lower part of the composition, on the left, is a small figure
bearing a club, the emblem of the strength of. the divinity.
A small figure on the right of the deity, and lower than the
feet, has the head of an elephant, as the Indian god: Gunees
is usually represented: Etymologists have remarked the re-
semblance between the name of Gunees and the Janus of the

3c 2 ancient

386 DESCRIPTION OF SOME INDIAN IDOLS

ancient Romans. The sect of Hindus who pay particular ado-
ration to Suria are called Sauras.

The third figure (Pl. XXIV. fig. 3.) represents Suria seated,
and attended by the shepherdesses, two of them above, with
each a wreath held out towards the head of the deity, two be-
neath, with their hands clasped in an attitude of adoration,
and sitting on a flower. On the left of Suria, is a small figure
holding a mace or club, representing the strength of the god.
In the left hand this small figure holds the weapon which
terminates in a ring. The sole of the left foot of Suria is
turned upwards, and a round body, like a piece of money, is
placed on it. In some Indian figures, the round body pla-
ced on the palm of the hand, or on the sole of the foot, re-
sembles the half-expanded flower of the water-lilly. The left
hand of the figure of Suria holds a stalk terminated by a
hexapetalous flower ; the erect figure of Suria before described
also holds a flower. The string of beads passing over the
left shoulder likewise occurs in both figures. A figure seated
with the legs across is on the head-dress of Suria. The bor-
der of the whole composition is a canopy formed of two co-
lumns, with capitals, supporting a trifoliated arch. The tal-
caceous stone of which this figure is sculptured, is of a finer
grain than the talcaceous stones of the other three figures.

In the valuable collection of Indian and Chinese works of
art, at the library of the India House, there is a sculpture in
black stone, 3 feet high, representing Suria holding flowers,
and attended by 9 small figures, in many respects resembling
the two figures of Suria here mentioned. But, in addition,
the figure in the India House has a charioteer holding the reins
of seven small horses; the horses are at the lower part of the
composition in front, and a wheel is on each side, so that the
whole composition is an image of the Sun in his chariot, and is
called Suria Vahana, or Suria Ratha, the chariot of the Sun.
The Vahana, or vehicle of some of the other Indian gods, is a

bird

ae LL. ae, 2

IN THE MUSEUM OF THE SOCIETY. . 8871

bird or quadruped upon which they ride. The charioteer
of the Suria Ratha, at the India House, is Arjuna or the
dawn. There is a figure discharging an arrow, which de-
notes the rays of the sun. A figure on each side with a
fly-flap and a fan, are the common attendants on royal-
ty in the Kast. Two male figures, one on each side,
holding a baton, are giants, emblems of force. A small
starving figure on each side, on the side of the stone, repre-
sents the effect produced by the absence of the sun’s heat.
The dress of this figure of Suria at the India House, differs
from that of Figs. 2. and 3., which were probably sculptured
in a more southern part of India. The figure in the India
House is represented with Tartar half-boots, in form like the
Hungarian. Tartar and Chinese sculptors are frequently
employed to make the idols in India, and they form the
dress, and other accessory parts of the composition, after the
manner of their country. The seven horses in this composi-
tion, may allude to the seven planets, and the days of the
week. The Hindus name the seven days of the week from
the regent genii of the same planets, and in the same order as
we do. It was from Egypt that the week, and the names of
the days of the week, were introduced into Europe.

There is another sculpture of the chariot of the sun at the
India House, in Coade’s baked clay, copied from a sculpture
which exists at Delhi.

Among the Indian sculptures at the British Museum, there
is a figure of Suria, between three and four feet in height,
with the usual attendant figures. This work is of a kind of
schistus.

The last sculpture (Pl. XXIV. fig. 4.) is Bupa, repre-
sented by the figure of a man seated, with the legs across,
and the soles of the feet, and palm of the left hand, turn-
ed upwards. On each of the soles, and on the palm, is
placed a round body like a coin. Buda, in his childhood,

was

388 DESCRIPTION OF SOME INDIAN IDOLS

was recognised by a round mark on the palm of the hand,
which indicated his divine nature. The hair of the head is
curled. The figure of Buda is seated on an expanded
flower of the nelumbo or red-flowered water-lily, which
grows in the waters of the Nile, of India, and of China, call-
ed by the Hindus the flower of the waters. This flower is
held sacred in India, and occurs frequently as a plinth, on
which figures rest in Indian sculptures ; it, is seen in the two
figures of Suria above described, (Fig. 2. and 3.) Behind
Buda are two quadrangular columns supporting an architrave,
and surmounted by a canopy. On the base of the composition
is the figure of a woman, with one knee on the ground, and
the hands lifted up. On each side of the woman is a lion.

The three great sects in India are the sects of Brahma, Bu-
da, and Iain. In a small bronze image from Ceylon, a fi-
gure in the usual attitude of Buda, is represented as seated on
the coils of a serpent, whilst the serpent extends his hood over
the head of the divine personage. Figures overshadowed in this
way are usually ascribed to the sect of Iain. In an image of
dark-coloured stone, about four feet high, at the India House,
Iain-Deo is represented as a man, over whose head a snake is
expanding his hood. The sect of Iain is not so widely ex-
tended as the others. Some authors are of opinion, that the
religion of Buda is derived from that of Brahma; and some
of the Brahmens consider Gautama Buda to be the ninth ava-
tar, or incarnate appearance of their deity Vishnu. Other
authors believe that the religion of Buda is quite distinct from
the religion of Brahma It is supposed by some to have had
its origin in the north of India, or Tibet.

Gautama Buda is a god who assumed the human form, and
was born of Maha Maya, the consort of Sootah Dannah Ra-
jah of Cailas. Cailas is a mountain in Tibet near the source

of

IN THE MUSEUM OF THE SOCIETY. 389

of the Ganges, covered with perpetual snow, which the Hin-
dus suppose to be the favourite abode of Mahadeva, the chief
deity of the sect of Siva. Gautama Buda became a priest, and
having attained that perfection of virtue and. supreme know-
ledge by which he was constituted Buda, he employed. his
time in converting men to religion and a virtuous life. The
word Buda signifies wise. He died at the age of 85; and
his death, which is the epoch from which the Siamese, and
the natives of Ceylon, reckon their years, is stated to have
happened 544 years before the Christian era*. The religion of
Buda prevails amongst the inhabitants of a very considerable
portion of the world; it is the religion of Ava, Siam, Ceylon,
and other countries of the East, and it is one of the religions
that prevails in the empires of China and Japan. In China,
Buda is called Fo, Sasya, Siaka, Xaca; in Japan, Bud,
Siaka, and Si Tsun, that is, the great saint: Gaudma in Ava:
Gautama Buda in Ceylon: in Siam, Samono Gautama and Sa-
monocodom. The religion of Buda was introduced into Chi-
na and Japan in the year 65 of the Christian era. Fo, which
is the Chinese pronunciation of Buda, belongs to a system
which has no connection with Fo-hi in the remote and fabu-
lous part of Chinese history, who invented the eight koa’, tri-
grams, or ancient mystical characters, composed of hori-
zontal and parallel straight lines, and taught the Chinese
the arts and sciences, as Tot or Hermes did to the Egyptians.
Clemens: Alexandrinus, who flourished in the reign of Seve-
rus and Antoninus Caracalla, about the year 200, mentions
the religion of Buda as prevailing in some parts of India +.
G Sims In

* See Laloubere royaume de Siam; and Dr Davy’s Account of’ Ceylon.

8 Eh de ray der é ob als Burle rude Waomyyshuasiy® ov Oe bmregBoaAny TyLVoTHTES te Osoy
rants CLEMENS ALEXANDR:: F¢opectrealn, lib: 1. sect xv. ‘Pp: 305,

390 DESCRIPTION OF SOME INDIAN IDOLS

In the Museum of the University of Edinburgh, amongst
several idols from Java, there is one of Buda, very much like
that represented at Fig. 4., and of the same kind of taleaceous
stone, so that they seem to be productions of the same school.
Others of these Java sculptures are of a dark-colourcd porous
lava.

In the British Museum there is a stone image of Buda
seated, with an attendant figure on eachcside ; on the back of
the stone is carved an ornamented pointed arch, of the form
called Gothic, with internal projecting cusps.

Figures of Buda, in the same attitude as that before us, are
described and engraved in Syme’s Account of the kingdom
of Ava, in the Museum Borgianum by Paulinus, in Kaempfer’s
Japan, and other works. All these images represent Buda in
the state of perfect quiescence and impassibility, to the enjoy+
ment of which he passed after he quitted his abode upon earth ;
this his followers consider to be the future state of maturity
into which souls perfectly virtuous are elevated.

In Java there is a low hill of considerable extent, covered
with a remarkable assemblage of large stone images of Buda,
placed in lines which go round the hill, and are parallel to
its base. A description of this monument is published in the
accounts of Java by Sir Stamford Raffles, and by Crawford.
Smaller figures of Buda, cast in bronze, are also met with in
Java. Pallas, in the course of his travels in the north of Asia,
collected some bronze figures of Buda, which are now in the
possession of Charles Hatchett, Esq.

There are inscriptions in the Nagari letters and in the San-
scrit language, on the base of the upright figure of Suria, and
within thé horse-shoe formed curve which is placed as a nim-
bus, behind the head of the figure of Buda; there is also an
inscription scratched on the plinth of the seated figure of Su-
ria, composed of letters less carefully executed, the work of an

inexperienced

ee

>:

© te

, IN THE MUSEUM OF THE SOCIETY. 391

inexperienced hand.» The inscription round the head of
Buda ‘is not so much obliterated as the others are. Ac-
cording to the translation which a learned orientalist was so
obliging as to give me, it relates to the “ Author of Creation
having contemplated for 1000 years, by reason of the existence
of irreligion.”

An ornamental border of a particular kind of foliage sur-
rounds the upright figure of Suria, and a similar border sur-
rounds the head of Buda. ‘This kind of foliage is also seen
in the small brass Javanese images of Buda.

All the figures have the lobes of the ears very long and
hanging down.

The seated figure of Suria and the figure of Buda have a
round mark on the forehead, between the eye-brows, like the
mark which the Hindus paint between the eye-brows, to de-
note the cast. The erect figure of Suria has an oblong mark
on the forehead.

The stone of which all the figures are carved, is a talcaceous
stone, called by mineralogists Talcaceous Schistus, but of a dif-
ferent grain in each figure. The stone of which the seated
figure of Suria is sculptured is of the finest grain. The others
are more schistose and granular. It is uncertain in what
part of India or of the eastern islands these figures were made.
Talcaceous schistus, similar to that of which they are formed,
occurs in different parts of the world ; it is quarried at St Ca-
therine’s near Inverary, and in other parts of the Highlands of
Scotland and Ireland. It is a magnesian stone, and is easily
cut by the chissel and file, so as to exhibit any figure that
the ability or genius of the sculptor can command. Crosses,
and arabesque ornaments on tombs, at Icolmkill and Loch
Awe, are carved out of talcaceous schistus ; it is one of those’

VOL. IX. P. If. 3D kinds

se

o
392 DESCRIPTION OF SOME INDIAN IDOLS, &c.

a

kinds of stone that can be wrought into form on the turning
lathe, as the Chinese do their image-stone, of which they
sometimes make cups. In the Valtelline, a valley on the
southern declivity of the Alps, kettles for boiling food, are
formed of talcaceous schistus on the turning lathe, and sent to
Milan, where they are sold on the streets. These turned stone-
kettles of the Valtelline were used also in ancient times, as —

we learn from Piiny, who makes mention of them..
XXVIII.

hall

cuinet l, wind i ee oe

a

XXVITI.— Observations on the Formation of the Chalk Strata,
and on the Structure of the Belemnite. By Tuomas A-
Lan, Esa. F. B.S, Edin. &c,

(Read 2d April 1821.)

Or the various rocks of which the Earth’s surface is com-
posed, there are some which present very satisfactory indica-
tions of their origin ; while others, when considered in that re-
Apeck seem to be placed almost beyond the reach of hypothe-
sis. The Granite and Trap rocks, by extending their ramifica-
Sak among their contiguous neighbours, distinctly avow, not
only asubsequent formation, but, in many instances, they present
the most unequivocal marks of an igneous origin. The Lime-
stones and Sandstones, however, are equally constant in their
indications: of aquatic. deposition, although, at the same time,
the assistance of another agency may sometimes be inferred,
when their consolidation and position are taken into the ques-
tion. . Of. all the rocks with which I am acquainted, there is
none ¥ whose formation. seems to tax the ingenuity of theorists
80. severely, as the White Limestone | or Chalk, i in whatever 1 re-

ara we. Rig think, fit to consider tet ae aa
“sp 2 ree et ese Te ES

394 ON THE FORMATION OF THE CHALK STRATA, ©

This rock, while compared with others, is of rare occurrence ;
for although it be found in various parts of Europe, it does not,
so far as we know, exist in any of the other quarters of the
Globe. In the south-east of England it may be said to abound ;
and in the north-east angle of Ireland, the white limestone pre-
vails to a great extent. Its connection with other rocks has of
late years occupied the attention of Geologists, and it has been
found to be a member of a considerable series, as uniform in
position with respect to its members, as any of those which
compose the great system of Werner; and although’it be
among the earliest of this series, yet in England it very ge-
nerally occurs uncovered, while in Ireland it is almost always
overlaid by the trap rocks. In both, it uniformly rests on the
Green Sand or Mulatto-stone.

The extent and position of the white limestone in Ireland
is somewhat remarkable. From Belfast it reaches all round the
coast, extending to Rathlin, and, with some trivial intermissions,
to Colerain ; and in a line to the westward of this, it runs south
through the middle of the county of Londonderry, to its verge in
the low lands which border Lough Neagh. On the west and south
of that lake it disappears ; but it occurs again to the south-east,
at Moira, in the county of Down, which connects itself with the
range in the neighbourhood of Belfast. In all this extent, the
limestone generally appears to dip inwards, so that within the
area of the space I have described, I understand it is nowhere
to be seen, although, from the position all round, there can be
little doubt that it exists. .

In England, it has also been observed, that there are two
distinct varieties of chalk, one of which is much harder than
the other; occurs in a lower position, and contains no flints, or
at least very rarely. The stratification of this variety is marked
by seams of a greyish-coloured chalk, containing probably an

' admixture

ed
_
a

Se

te ke

Ss ee ee

Sule

AND STRUCTURE OF THE BELEMNITE. ' 895

-admixtute of clay along with shells. The upper chalk is dis-
tinguished by its eee hardness, and the ois of flint
“with which it is accompanied. |

In Ireland, excepting when traversed by dikes, 1 have never
observed but one kind} it is harder than any of the English
chalks ; it contains quantities of flints, and, as we shall shortly
see, a tolerable abundance of organic remains. It is used for
all the different purposes of limestone, including building.

The alteration produced by the occurrence of a. whin-dike
has been observed by every geologist who has visited this part
of the country. In place of the dull earthy fracture of the
chalk, it presents a crystalline disintegrated mass, very friable
and phosphorescent, of a pale green colour, and maintain-
ing these characters only in the immediate vicinity of the
dike.

Geologists seem to have been very shy in treating of the
formation of chalk ; they have in general been contented with
quoting the opinions of some predecessor, very little that
can be considered original, being to be found in any of the
geological works I have’ examined. Some ingenuity has, how-
ever, been displayed in ringing the changes on the same ideas ;

‘but in the progress of this investigation, we find very little
added to the first projected opinions. Professor JamxEson sa-
tisfies himself with placing the Chalk at the end of his great:
Limestone series, (System, p. 91. 1818), and considers that it
agrees admirably with the preconceived ideas of the diminution
of the waters, with which Werner inundated the surface of the
Earth ; and he adds, that its occurrence on the sea-coast, and
its earthy aspect, point out the lateness of its formation, (176).
Why ‘the proximity of the sea-coast should afford any evi-
dence ‘of the period of its formation I cannot conjecture, as we
know ‘of no rock that is not washed by the waves of the ocean.
— Mr.

396 ON THE FORMATION OF THE CHALK STRATA,

Mr Jameson avoids giving any opinion of his own on the
formation of Flint, in any of his works on Mineralogy and Geo-
logy. He contents himself with stating, “ That the beds of flint,
and also the tuberose and other shaped masses found in chalk,
appear to have been formed at the same time with the chalk.”
But he adds, “ Wxrwer is of opinion that the tuberose, and
many other forms, have -been formed by infiltration, and
conjectures, that during the depositions of chalk, air was evol-
ved, which, in endeavouring to escape, formed irregular cavi-
ties, which were afterwards filled up by infiltration with flint,”
System, vol. i. p. 235. 1820. This opinion was also embraced by
Kirwan, which is a little remarkable; for although it be very
probable that WERNER never had an opportunity of studying
the chalk strata, Kirwan must have seen them frequently, and
the most simple inspection of the singular regularity with which
the flints are disposed in parallel lines to each other, ought at
once to have obliterated any such opinion; for supposing it
possible, had air been evolved, to the extent of one single line
of these flints, a vacuity, equal to the whole plane of the rock,
or nearly so, must have been formed, and the superincumbent
strata as it were suspended,—a position not likely to meet
with support even from Werner himself, particularly when it
must be conceded, that the vacuity so formed must be multi-
plied by the number of lines of flint that occur in the bed of
chalk.

Besides, it is difficult to suppose that this discharge of
air, from a stratum calculated to extend to the thickness of 600
feet, should have been confined to certain straight lines. Air, to
have been evolved, must first have been generated, and, like the
nuclei in amygdaloid, must have pervaded the mass irregularly
and indiscriminately, throughout its whole extent. It must be
observed too, that it was not till after the air was evolved. that

the

AND STRUCTURE OF THE BELEMNITE, 397

the infiltration took place, so that it is not only a vacuity, but
a.vacuum, that is required for the operation.
_, Another hypothesis, equally destitute of philosophic induc-
tion, has been proposed to account for the formation of flints ;
and because they present an outer crust, although perfectly si-
liceous, as white and as opake as the chalk they were lodged in,
some speculators have not hesitated. to urge the probability of a
transmutation ; and Baxewez.., (Introd. p. 171. 1813.) gravely
tells us, “ that as it is acommon belief among working miners,
that lime and flint are changed into each other, we should not
hastily reject the opinions of practical men, but examine whe-
ther their opinions be opposed to facts only, or.to theories.”
As well might we listen to the fancies. of the practical men at
the diamond-mines of Mallevully, who insist that the precious
gem is actually generated among the turned-over rubbish ; an
idea which, had it been- entitled to, more attention than the
transmutation of the precious metal, must have been traced
and determined long ere now..
On the subject of transmutation, however, Parkinson, Hse he
p- 322,. observes, “ In the present advanced state of chemistry,
it\is unnecessary to. dwell on the opinion: which has been en-
-tertained by M. Parrin, M. ps Carosi and others, that chalk
undergoes a conversion into flint, except for the sake of re-
marking, that all those apparent transmutations which have
given rise to this opinion, are easily explained, by supposing a
partial introduction: of a: siliceous fluid in: various quantities,
into, porous calcareous. earth.” And after a good deal of argu-

_ ment on the subject of this formation, he arrives at the follow-

ing supposition, vol. i. p. 328... ‘* Whether it be believed that.
these several bodies owe their existence to fire or water, it will,
Leoneeive,. be. evequally. admitted, glint they have been formed

Te) toe in:

398 ON THE FORMATION OF THE CHALK STRATA,

in cavities previously existing in the matrix in which they are
contained. I suppose, then, that one of these cavities becomes
filled by some small aperture, with a liquid holding silex in
solution; that siliceous crystals form all round the cavity, ex-
cept at the aperture, where there is nothing to attach them-
selves to; and that an aperture in some other part, allows a
regular escape of the fluid, by which a correspondent supply is
demanded from the first mentioned aperture, until, after per-
haps the lapse of ages, the crystals fill up from the bottom
and sides to the aperture by which the fluid was admitted, and
form a solid crystallised mass from which the water is exclu-
ded. Nor does it even appear necessary for the formation of a
solid crystalline mass, that there should be more than one
opening, that which admits the fluid into the cavity ; since the
calibre of the opening, bearing a proper proportion to the ca-
vity to be filled, it will remain open until the mass of crystal-
lization is completed ; it being reasonable to suppose, that the
fluid containing the silex would, in consequence of its superior
gravity, be continually supplying the place of that which, ha-
ving been deprived of its silex by crystallization, would of
course tend upwards ; and thus might the cavity become entire-
ly filled by crystallization, to the total exclusion of the sol-
-vent.”

The surprise that I have expressed at the conclusions of
Werner and Kirwan, is perhaps more applicable to this cele-
brated fossilist ; for his works bespeak the labour of a lifetime
on the very soil we are now engaged in. He does not, indeed,
suppose a vacuum to have existed in any part of the strata, but
he supposes an infiltration percolating through hundreds of
these ranges of flints, which, to do its work, must have first pro-
ceeded to the lowest, and gone on gradually towards the top ;

_ but,

~

AND STRUCTURE OF THE BELEMNITE. 399

but, in place of this, the highest range is the first that would
arrest the loaded siliceous solution, and that formed, the flints
being often so closely deposited, as even to become continuous,
the connection must have been interrupted, and many of the
lower cavities left vacant,—a circumstance unknown in the his-
tory of chalk-rocks. It may be remarked, however, that Mr
Parkinson’s observations are meant to apply to the formation
‘of pebbles as well as flints; but the formation of agate and
calcedony lead to a totally different inquiry.

The essay read by Dr Hurron on the 7th of March, and
4th of April 1785, on the Theory of the Earth, published in
the Transactions of this Society, is well known to embrace, in
all its plenitude, the igneous theory of that philosopher ; and
in it we find the opinion which he entertained respecting the
formation of flint to be as follows. “ The actual form in which
those flinty masses are found, demonstrates, Ist, That they
have been introduced among those strata in a fluid state, by
injection from some other place. 2d, That they have been
dispersed in a variety of ways among these strata, then deeply
immersed at the bottom of the sea. And, lastly, That they have
been there congealed from the state of fusion, and have re-
mained in that situation, while those strata have been removed
from the bottom of the ocean to the surface of the present
land.” Trans. vol. i. p. 232.

The elegant commentator of Dr Hurron only seeks in the for-
mation of flint for an illustration of the igneous origin of that
substance. He observes, § 20. “‘ The round nodules of flint that
are found in chalk quite insulated, and separate from one ano-
ther, afford an argument of the same kind (alluding to fluidity
produced by fusion), since the flinty matter, if it had been car-
ried into the chalk by any solvent, must have been deposited
with a certain degree of uniformity, and would not now appear

VOL. IX. P. II. 3E collected

400 ON THE FORMATION OF THE CHALK STRATA,

collected into separate masses, without any trace of its exist-
ence in the intermediate parts ; on the other hand, if we con-
ceive the melted flint to have been forcibly injected among the
chalk, and to have penetrated it, somewhat as mercury may by
pressure be made to penetrate through the pores of wood, it
might, on cooling, exhibit the same appearances that the chalk
beds of England do actually present us with.”

In the splendid work of Sir H. Encrerierp, On the Isle of
Wight, we find the following observations : “ With respect to
the formation of flint itself, it cannot be doubted that this se-
paration of the siliceous matter from the calcareous took place
after the formation of the strata, and that the flints were not,
as it would appear at a first glance, deposited in alternate
strata with the chalk. The extraneous fossils found in the
chalk often afford singular proofs of this. Many echini are
seen filled with flint, which has, after completely filling up the
cavity of the shell, formed a large bulb at the orifice of it, as a
viscid fluid would do;” and after some farther remarks, he
proceeds to ask, “ What agent has in this manner, at ¢wo dif
ferent times, separated the siliceous from the calcareous mat-
ter ? and, How could the flint, when separated, form itself into
masses in the solid chalk ?—for it cannot be supposed that the
flint only ran into cavities before empty, as in that case some
of these cavities ought to be found either totally or partially
void; but no such have ever been discovered in chalk,” p. 20.

The two different periods of separation of which Sir Henry
talks, allude to the supposed subsequent filling of certain fis-
sures, which traverse the chalk in a contrary direction to the
lines of the strata, which he describes as being “ seldom above
two inches wide, and seem to have been formed from each side
towards the centre, which often contains some loose calca-

reous powder, inclosed between the two siliceous plates,” p. 20.
These

AND STRUCTURE OF THE BELEMNITE. 401

These veins may perhaps be considered as veins of secretion,
formed in the fissures which may have occurred in the strata,
during the dependence of the operations which produced the
tuberose arrangement of the flints.

We are indebted to the ingenuity of Professor BuckLanp of
Oxford for another idea respecting flint. It was observed,
that a variety of the nodules which occurred in particular gra-
vel pits, presented something of an uniform shape, which,
when broken, were found to contain zoophytic remains, such
as alcyonia, corals, and sponges of different kinds, sometimes
so perfect, as to be extricable from the outer case, when for-
tunately and carefully broken ; at other times, when the exter-
nal contour of the nodule bespoke a similar internal appear-
ance, the mass would be found perfectly solid throughout, and
the shape only of the organic body traced on the internal frac-
ture, in colours of a shade differing from the general mass of
the flint, or slightly tinged of a delicate purple, when the tex-
ture passed into that of calcedony; and so uniformly were
these appearances connected, that where the slightest symp-
tom of any of them occurred, it was held as indicative of one
and the same origin. The origin of flint itself was by this
analogy attributed to organization, though perhaps on grounds
not altogether thoroughly investigated.

We find little in the French works tending to illustrate this
subject. Brocuant, following Werner, considers flint to owe
its origin to infiltration. Broeniart states, that some have
supposed flint to be formed by infiltration, introduced into ca-
vities formerly occupied by mollusca and zoophytes,—an hypo-
thesis which, he says, though admitted by a number of geolo-
gists, is exposed to considerable difficulties; and he adds, that
the observation of M. Gittzr Laumonr tends to support this
supposition ; he having remarked that a tail of silex often pro-

3E2 ceeds

402 ON THE FORMATION OF THE CHALK STRATA,

ceeds from the mouth of the fossil echinite found in chalk, as
if the animal matter which had flowed from that orifice had
been petrified and changed into silex. He hazards no opinion
of his own. Traité, vol. i. p. 316. 1807.

The recent work of Dausuisson, which is one of the most
elaborate and extensive that has been published for some
years, goes a little deeper into this subject. Talking of the sphe-
rical masses of flint, § 119. found in the limestone of Bavaria,
he observes, “ that they very probably owe their origin to a re-
union of siliceous particles, which were disseminated in the
calcareous mass still soft or fluid; yielding to their attractive
force, they had grouped themselves, and, as it were, formed.
themselves into balls, round a centre. If this arrangement
had not been accomplished in so perfect a manner, or that the
attractions had operated in several, or around different neigh-
bouring centres, tuberose masses would have been the re-
sult, and not balls; such is probably the origin of the flints
which occur in such abundance in the chalk and other calca-
reous beds.”

Having thus described the mode of formation of flint, he
adds, § 301. “ that the particles of carbonate of lime, which have
formed the secondary limestone, appear to have been frequent-
ly mixed, in the fluid from which they were precipitated, with
particles of silex, which were deposited at the same time. If
these had been in small quantity, and had rested disseminated
in the mass, limestone, impregnated with silex, would have
been the result, and if they had united, a few detached flints
would have been produced ; but if they had been abundant,
either the Silici-calce of SaussurE would have been formed,
or a great number of tuberose flints. I have sometimes seen
them so abundant, that they touched, and the limestone only
filled the interstices. At some moments, and in some points,

the

AND STRUCTURE OF THE BELEMNITE. 403

the precipitation might have been entirely siliceous, and then
beds, or parts of beds, entirely of flint, would have been form-
ed. The particles of silex, in gathering themselves into balls,
have occasionally drawn along with them some carbonate of
lime. Hence those masses are composed of two substances,
pure silex in the centre, and Sélici-calce on the surface.”

“ These flints, after their formation, having remained some
time in a state of softness, which permitted them to yield to the
compression occasioned by the weight of the superior masses,
seems to be indicated by their frequent flattened form, or per-
haps that form indicates, that the force which has united the
particles, assisted probably by this weight, has exerted its action
more in a vertical than a horizontal direction ; the siliceous
particles disseminated in a bed, in a state of semi-fluidity, will
have descended to the lower part of the bed, and there have
united.” Ll:

I confess it is difficult to follow the meaning of M. Dav-
Buisson throughout this theoretical disquisition. I have en-
deavoured to render the quotations as intelligibly as possible,
but still there is much obscurity in what he says, particularly
respecting the descent of the siliceous particles, because
exposed to pressure. Unless he could have shown that that
pressure had acted more directly on the silex than on the
carbonate of lime which contained it, it is not easy to con-
ceive how it should have changed its position either up or-
down.

Although I have extended these extracts much beyond
what may appear to have been necessary ; yet the materials, on

-the whole, will be found meagre and unsatisfactory, and very-
inadequate to afford any conclusive deductions on. the forma-
tion of either Chalk or Flint. Some of them must be altogether
rejected ; but from others a few scattered hints may be elicit-

ed...

404 ON THE FORMATION OF THE CHALK STRATA,

ed. We must therefore revert to an examination of the rocks
themselves, to the circumstances in which they are found to
exist, and to the fossil remains which are peculiar to the strata
of chalk; and endeavour to ascertain how these circumstances
can be brought to combine with the formation of the beds
themselves.

In England, particularly in the Isle of Wight, and on the
coast of Dorset, where the features of that rock have been so
faithfully delineated by the inimitable pencil of Mr Wenstrr,
several sudden and very remarkable elevations of the strata
have been described. The limestone, after extending for a con-
siderable distance, in a position varying little from perfect ho-
rizontality, is all at once thrown up, and stands upon edge,
no alteration having taken place in the arrangement of its
flints, which are now piled on the top of each other, and ex-
posed to an influence, with respect to the superincumbent
weight, the very reverse of that mentioned by Davsuisson.
In the Isle of Wight at Freshwater and Culver cliffs, and
Scratchell Bay, and on the Dorset coast at Worthbarrow Bay,
Handfast Point, and Batts Corner, magnificent examples of this
are afforded. In all, strings of flints are seen disposed through-
out, in lines parallel to the strata, in every altered position.
Where we find similar bendings in strata, that are usually ho-
rizontal, the proximity of a whin-dike, an inyasion of granite,
or some of the other crystalline rocks, afford the Huttonian
some grounds of conjecture as to the cause ; but the eccentri-
cities of the English chalk are dependent on some other cause,
—a cause which, from its effects, denotes itself to have been of
the most powerful description, and one to which Hurron
alone has alluded, in his hypothesis of the elevation of the
strata from the bottom of the sea. This force could not be
supposed always to have acted with perfect uniformity. Hence

those

———

AND STRUCTURE OF THE BELEMNITE. 405

those contortions and elevations so remarkable at the spots I
have enumerated ; and the probable demolition of a large pro-
portion of these strata, the remains of which are spread over
so great an extent of England, in deposition of loose alluvial
gravel.

The nature of the fluid from which the chalk strata have been
deposited, I conceive it an idle pursuit to inquire into; but
that they were deposited from a fluid is admitted on all hands,
and that they were deposited, not where they now are, but
when deep under the surface of the ocean, is proved beyond a
doubt, by the marine remains, and only marine remains, which
are peculiar to these strata. No metallic substance has ever
been found in chalk, except some iron-pyrites, and that to a
very limited extent ; but the organic bodies have been nume-
rous, and some of them in the most beautiful state of preser-
vation. Difficult and accidental as it must be to extricate such
objects, I have sometimes seen a fossil resembling the Echinus
circinatus of GuatiER1 (whose spines are two or three inches
in length) very entire, which denotes that it must have been
deposited at a moment when the most perfect quiescence pre-
vailed. These appear to me to be legitimate and sound data,
on which to ground opinions respecting the nature of the chalk
strata, and a more close examination of the fossil remains will
perhaps lead to some probable conjectures respecting the for-
mation of the flints.

I conceive it quite unnecessary to enter upon any refutation
of WernEr’s idea, of cavities being left by the expulsion of air,

“not only from the impossibility of the limestone remaining
suspended, as before remarked, but that these very flints some-
times contain organic remains entirely enveloped, which could
not have been introduced by infiltration, and must have been
in the open sea, when the two substances, the siliceous matter

of

406 ON THE FORMATION OF THE CHALK STRATA,

of the flint and the fossil, came in contact with each other. It
is equally difficult to embrace the idea of Hurron, that flint
was introduced among these strata from some other place, as
no forcible introduction of flint, in the state of fluidity, which
he supposes, would produce the long and extensive lines of
spherical and tuberose masses, drawn parallel to each other
with a precision almost mathematical, which the chalk strata
everywhere exhibit; and the force by which that introduction
is supposed to have been accompanied, was calculated only to
annihilate the very delicate texture observable among the fos-
sils which are included in it. Operations much more quiescent
in their progress were necessary to the original arrangement
of these objects,—the parallelism of the flints, the delicacy of the
fossils, equally demand this. When these were got together, se-
cured, and hermetically sealed, in their position, they could no
longer be deranged, they could no longer be injured by for-
cible agitation, or concussions of any kind; and it is necessary
to presuppose some security of this sort, before we can specu-
late on the elevation of a single bed of chalk.

I was led to these conclusions by an examination of some
fossils I lately obtained from the north of Ireland, which, when
combined with the consideration of the highly inclined chalk
strata on the coast of England, I conceived were capable of
throwing some light on the formation, not only of the chalk,
but also of the flints, which have hitherto presented so much
difficulty to the theorist.

The fossils which principally occur in the Antrim lime-
stone, are the Belemnite and Echinite. Ofthe latter there are
different species, and they vary in bulk, from the size of a
wren’s egg to that of a turkey’s. When enveloped in chalk,
the echinus is entirely calcareous, having the shell converted
into cristallised carbonate, while the interior is filled with the

usual

AND STRUCTURE OF THE BELEMNITE. 407

usual white limestone. When inclosed in flint, the shell still
remains in the same state, and, as Laumont has observed, the
interior and exterior flint are connected at the vent of the ani-
mal, and when the carbonate is removed by means of acid, the
flint appears to have penetrated: all the minute pores, and
presents sharp: and prickly ridges along the different lobes or
portions of which the shell of the echinite is formed.

. The Belemnite is a very common fossil, yet; for the sake of
perspicuity, it is necessary to describe it in a tM man-
ner.

It occurs in great nbd in the south of Bintan and
although Parkinson and others describe several varieties, the
belemnites of Antrim appear to me to: be only of one: kind,
pretty much of a size; measuring in general: about: three or
four inches in length, and from half an inch to three-fourths
in thickness. The form is that of a. cylinder, terminated at
one end with a conical point, furnished with'a slender process,
of about a quarter of an inch in length;)but it:isonly when
the belemnite has been inclosed in flint: that: this delicate
member has been preserved. At the other extremity, the fos-
sil is always more or less broken, and provided with a cavity
or alveolus, which is filled up with the material in which it has
been imbedded. This cavity is conical, terminating with a
sharp point, and occupies a situation a little to one side of the
centre of the cylinder.

In composition, the belemnite, whether inclosed in lime-
stone, flint, clay or sandstone, is uniformly formed of cristal-
lised carbonate of lime, striated and radiating to the circim-
ference, from a line which passes from the apex of the alveo-
lus to that of the fossil.

_» In colour it varies. Those that are found: in al where
- clay abounds, are opake, and of a dark-brown; while those
ooWOL. TX. P. IL. 3F that

408 ON THE FORMATION OF THE CHALK STRATA,

that occur in chalk and flint are translucent, and of an amber-
yellow. , 4 etve

This curious Salis of elias nature sihothiag but the most
vague conjectures have hitherto been hazarded, seems to have
been the appendage of some animal, handed down to us pro-
bably unchanged since its creation. It will be remarked, that
its structure is quite different from that of other caleareous
fossils, which are formed in general of the common rhom-
boidal carbonate, while it is composed of radiated’ striae, di-
verging from a point, which appears to have been dependent
on some internal organisation. These striz are interrupted
by concentric lines, which are not frequently visible, although
they are rendered so by the action of ‘acid, and sometimes
are displayed in the longitudinal fracture.'' This arrangement
seems to indicate the growth of the animal, and had the be-
lemnite undergone a conversion like other petrified substances,
must certainly have been obliterated. lstey" bets

On this account we may perhaps be allowed to consider the
belemnite as unaltered; but to what species of animal it has
belonged, no conjecture can be formed. » The thick end of the
fossil is-always: broken, as, in. consequence of the ‘conical form
of the alveolus, it is: reduced tava thin, delicate edge, and may
have been attached by. ee matter to the cr of an
animal it belonged ‘to.

Although the alveolus be very patter filled seit the ma-
terial in whichi-tlie fossil is imbedded, it likewise happens, oc-
casionally, to present an organic structure. “When the Antrim
fossils, which are formed in: flint, have: been reduced by acid,
the siliceous cone:is:found: to be: impressed with rings; set: at
regular distances ; but this is only superficial, as the flint:itself

breaks in its usual conchoidal form; without:any interruption |

from the external appearance. It is: different, however, in
: tk |. some

at<.

AND STRUCTURE OF THE) BELEMNITE, 409

some‘ of the calcareous specimens; for when the cone is bro-
kén across, it separates by these lines, leaving in the upper part
a concavity, and on the lower a corresponding convexity, and
‘exhibiting a spot occupied by a siphunculus or duct, like the
nautilus and other shells, at the side of the concamerated cone
which is nearest to that of the belemnite; the use of which,
according to Parkinson, vol. iii: p.129. ‘ in all the multilocu-
lar shells, was to bring the animal to which they are appended,
with’ its shell; to.a degree .of specific gravity,: so-near that of
water, as to render it capable of being raised or sunk with faci-
lity, by the apparatus of its siphuncle.”». I conclude that this
part of the belemnite must have existed in such a state, as, by
its lightness, it’ must, like the closed scheiemane have served as
a float to the animal. )

_ Whether this was the use for sihiel the bréanization of the
belemnite was destined, entirely depends upon the nature of the
animal:to which it was appended... Any conjectures on that head
must:\therefore be wholly gratuitous. One thing is evident,
however, and. marks: a conspicuous distinction between the
concameration, if L:may use that expression, of the belemnite
andthe nautilus : the chambers of the last are separated from
each! other by’a:firny compact’ shell, while: nothing of the kind
appéats'to have éxisted in the belemnite. Its organisation may
have been composed. of a soft membranous substance, easly
removed-on the animal being deprived of life.

This supposition is somewhat confirmed by the appearance
of ‘the belemnites found’ im the Antrim chalk, which must
have’ been dead shells (as that expression is understood by nia=
furdlists) a the time they were inclosed in the strata; for, bé-
sides'all‘appéarances of the’ body to which they had’ belonged
beiiig totally obliterated, the’ fossil itself is not only fractured
at the édgé of the alveolus, but is frequently, though not al:
ways, found to have been perforated by serpule, and thus

‘ 3F2 affords _

410 ON THE FORMATION OF THE CHALK STRATA,

affords one of the most singularly beautiful phenomena that
I have had occasion to observe, connected with the mineral
kingdom. Some also appear to have been broken, before they
were inclosed in the flint, which has faithfully retained the im-
pression of the fracture as perfectly as the finest sealing-
wax.

It is some years ago since I was first led to this observation.
While examining a flint which contained a portion of a be-
‘lemnite, I remarked on the calcareous radiated section of
the fossil two or three circular specks :of flint; and as they
also made their appearance at the other end, it occurred to
me to remove the calcareous matter by means of acid. On
the accomplishment of this, I was surprised and much inte-
rested to find, that these specks were the extremities of cylin-
drical portions of flint, having exactly the form and appear-
ance of arteries, and connected with each other, and with that
portion of the cone which remained, by means of smaller
fibres representing veins, and. affording the most striking re-
semblance to an injected anatomical preparation. This disco-
very naturally raised my curiosity; I searched’ my cabinet,
but in vain, to find specimens of the same kind.» I endea-
voured, but with similar success, to procure some from
Ireland, and it was not till last autumn (1820,) when I was in
that country, in company with Lord Compron, that I was
enabled to procure the necessary supply. In the extensive
lime-quarries of Mr Farrex of Larne, I pointed out to the la-
bourers the belemnites imbedded in flint, which were quite
familiar to them, and for a trifling gratuity, an abundant quan-
tity was sent me in a day or two to Belfast. On submitting
them to the acid, almost all have afforded something ex-
tremely interesting and curious, and have opened up a source
of investigation which may probably lead to unexpected, re-

sults.
The

Teun. Vol Ipuge $b.

Eng Prax the Rdin’ Roval Soc

PLATE XiV

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WHLiars Sculp ©

del #

KK Greville

‘ AND STRUCTURE OF THE BELEMNITE. 411

The means I employed was to dilute muriatic, acid with
four or five waters, and perhaps this was too rough an applica-
tion for the very delicate and minute fibres which were often
exposed to it, as I found in too many instances, that, after the
specimens were dried, the flinty arborisations would sometimes
fall to pieces. This extreme delicacy rendered an exhibition
of these specimens’ impracticable, which is to be the less re-
gretted, as I am indebted to the elegant and elaborate pencil
of Mr Grevitie. for the most faithful representations of them ;
and which I have now the honour of pnttng to the So-

{

ciety. 3, a0

No, 1. (Plate X XV.) the first drawing is a portion of a large
belemnite, selected to shew the nature and situation of the
alveolus, and the concamerated cone by which it is occupied.
‘This specimen was sent me pe Dr F ITTON ‘from Northamp-
ton.

No. 2. Is a flint from. ‘shich the belemnite ciate of its
own accord, and i is selected on account of the indication of
a serpula, which seems to have been attached to the surface
of the animal. n several of the specimens, the external

surface seems to have been rough, and covered with minute
protuberances, corresponding depressions being observable
on the flint.

No. 3. :In this specimen the cone | fills up entirely the base of
the belemnite; the trace of its circle being lost in the sub-
stance of the flint. At its apex there is a delicate capillary
process appended. This is the process, which proceeds from
the apex of the cone, to that of the belemnite. I have found
it always extremely delicate, and it sometimes fell to pieces
by its own weight. There are also some of the little branches
of flint, which-have occupied the pores or perforations allu-
dedto.

ay ‘ ' f , ' No. .

:

412 ON THE FORMATION OF THE CHALK STRATA,

No. 4. This beautiful specimen resembles the first I obtained.
Along side of the cone are those tubes and capillary vessels
connécted with the cone, and with the sides of the belem-
nite, and entangled in lace-like work, small, irregular, glo-
bular masses, all connected by the most slender fibres. —

‘ No. 5. In this specimen the fossil is inverted, the base of the
cone being uppermost. In order to prevent it from falling
to pieces, the dissolution of the carbonate was watched,
and stopped, when the specimen was sufficiently displayed ;
it will be seen how much the vessels which have here exist=
ed, have the character of organization ; they twist and range
about, quite like the gut of an animal. Still, as we see so
little resemblance between this and the other specimens, we
cannot but hesitate to attribute it to an origin which be-
speaks uniformity and regularity. —

No.6. Plate XXVI. This specimen is singular ; it has evidently
been broken off at each end ; the cone, of which only a small
portion remains, rests upon flint, which is impressed with the
radiated structure of the fossil, andthe upper part is broken
off at right angles, showing not only that it must have been
a fragment of the belemnite, when originally inclosed m the
flint, but also that it was then possessed of the same radi-
ated structure it now presents. Hence, if it be a petrifaction,
in place of an original formation, as I have been led:to con-
sider it, it must have been transformed previous to its inclo-
sure in the flint. Upon the surface small branches’ of arbo-
rescent flint may also be observed, as if the original had
been covered with some delicate conferva, now converted
into silex. There are also some of those cylindrical branches
very short, as if they had occupied only the commencement
of the perforation, which have proceeded’ from the surface
inwards, without the appearance of fracture at the extremi-

ties;

Se en sa

—_—

Soc. Tran Vol Xk page #12

Eing @ tor the Edin? Royal

PLATE XXVI

\

I)

1.

Eos

Fig. 9.

RKCreville del’

WHLizars Sculp®

AND STRUCTURE OF THE BELEMNITE. 413

ties, which are rounded off. These are very like the perfo-
rations of a worm, and have induced me to. believe, that

_ many of them are merely casts of flint, in cavities formed _
_in that manner. .-

Nos. 7, 8, ands 9. In these specimens the flint which has been

_ anew appearance, which may perhaps be best compared to

_ the oyarium of some animal. Small roundish masses are
connected and entangled with each mther by thin and very
delicate threads. —

No. 10. Is one of the globular masses * larger than usual, but
also a little magnified in the drawing. I should observe, that
the flint in most, of these fossils approaches to calcedony, and
is lighter in its colour than the general mass. It sometimes
presents an opake chalky-looking aspect, which, I presume,
arises from an admixture of calcareous. matter, for I have

found this variety very liable to crumble into, dust, aften the
operation of the acid. ...

No. 11. Is the same fossil found in the limestone, and by be-
_ ing broken longitudinally, there appear in the section of it
cavities filled with chalk, as they. would have. been. filled
_ with flint in the. specimens-I have described... I have.a great

‘Many more of the same kind, particularly, of the flints, and
some of them, presenting the most, beautiful arborisations I

_ ever saw, quite; similar to the most, delicate sea-weed, which

had apparently: bei ati to. ae outer surface of the be-
Jemnite. 9s 0°
This

* In a of this kind, I’ have noticed! that the connection. between these
alsin Maasses,; is, maintained, more. partigularly. by, two;fibres, larger. than the

others, and more uniform in their position.

414 ON THE FORMATION OF THE CHALK STRATA,

This curious arborescent, and most delicate arrangement of
the siliceous matter, naturally gave rise to conjectures on the
probable mode of its introduction into the fossil. From the
specimen designed in Fig. 6. it is quite evident, that a frag-
ment only was there inclosed, and the enveloping material
being continuous with the cone as well as the little branches
formed ‘i in the perforations, by which it had been penetrated,
it is certain that these cavities must have been made in the
calcareous mass of the belemnite. I am possessed of a speci-
men from Oxfordshire of a belemnite which is covered with
serpulee, and penetrated with numerous worm-holes ; and sup-
posing these to have been filled with flint, and laid open by
the removal of the calcareous portion of the fossil, we might
expect a preparation exactly similar to those I have been de-
scribing. The great dissimilarity among the specimens, seems
to preclude the possibility of attributing their structure to orga-
nization, however strongly some of them may resemble it ; and,
after all, it may be, that this arrangement is due to more than
one cause. One thing like uniformity in the interior structure,
which may. certainly be laid hold of, is the projection of the
delicate fibre, from the apex of the concamerated cone, along the
centre of the radiated cylinder, to the extreme point of the be-
lemnite. This is partly distinguishable in the drawings, Nos.
3. and 9.; and, as I have observed it in many others, I think
it may, with propriety, be attributed to an organic connection
between the siphunculus and the apex of the fossil, which Par-
KINSON says, Vol. iii. p. 130., has already been cana by
Watcu.

With respect to the singular arrangement displayed in Figs.
7. 8. and 9.; on a minute examination of these, and several
other specimens, it is very difficult to come to any conclusion.
The first idea that suggested itself, was the striking similarity

to

AND STRUCTURE OF THE BELEMNITE. 415

to the ovarium of an animal, as already stated ; but this is a
pursuit I must leave to the comparative anatomist. He may
find in the threads by which these rounded masses are con-
nected, more uniformity than could be attributed to the acci-
dental perforations of a worm ; nor do I think the elegant and
delicate moss-like arrangement of the fibres with which they
are surrounded, seem likely to have accrued from any such
operation ; and as an organised connection has been point-
ed out, extending from the siphunculus to the apex of
the belemnite, perhaps more practised eyes may be able to
trace it farther in these or other specimens*. But as these
drawings shew, it is not the belemnites that are found in the
flint only that present this curious internal structure, for those
which occur in the chalk, when broken in the direction of
their axes, also exhibit the same phenomena, having the ca-
vities filled with white limestone, which, when contrasted with
the amber-coloured radiated spar of the belemnite, is exhibit-
ed with perfect fidelity.

I have found several having these cavities filled partly with
chalk and partly with flint; but this only when the belemnite,
by extending beyond the mass of the flint, was partly sur-
rounded by both.

Now, under what circumstances was it possible, for either
the white limestone or the flint, to insinuate itself throughout

VOL. IX. P. Il. 3G the

* Naturalists, having any connection with Ireland, will have no difficulty in
supplying themselves with specimens; for although Mr Parxtnson mentions the
belemnite being found transfixed in flint as a circumstance of some rarity, the
north of Ireland affords an unbounded resource ; and it will be very interesting to
me to learn, that this fossil, found under similar circumstances in other places,
presents the’same’ phenomena.

416 ON THE FORMATION OF THE CHALK STRATA,

the delicate ramifications that are thus laid open to view? Cer-
tainly not with any degree of probability, by the deposition of
the calcareous matter, or the infiltration of the siliceous, as
suggested by Werner ; nor is the forcible introduction of sili-
ceous matter, as suggested by Dr Hurron, at all compatible
with such delicate structures.

I am aware of the temerity of offering any thing like a new
doctrine on the formation of the materials I have been now
treating of, and perfectly sensible of the desire which, in spite
of us, exists among us all, to find objections to any novelty of
the kind, rather than to contribute our mite to its support, or
to trouble ourselves about the investigation of the grounds on
which it is established. Still, however, I cannot help stating, that
after pondering upon this subject,and taking into account all that
I am acquainted with respecting the strata of chalk-rocks, it ap-
pears to me that they must have been deposited in a very quies-
cent state; that the calcareous and siliceous matter had, by
their respective attractions, separated, and that the latter was
deposited in thin and multiplied continuous seams, in the man-
ner conceived by Davsutsson ; that the fossils were promiscu-
ously intermingled throughout, when the specific gravity of each
was equal, so that they occur in all parts of the stratum ; that the
whole was, according to Dr Hutton, exposed under pressure to
a great degree of heat, which not only attenuated the substance
of the carbonate of lime, and rendered it capable of being for-
ced into the minutest cavities of the fossils ; but also, by fusing
the thin seams of siliceous matter, enabled that substance, by
new and more powerful attractions, to collect itself in the sphe-
rical and tuberose groups it now exhibits, enveloping the fos-
sils which were previously intermixed with it, and, from the
pressure it maintained, forcing its way into all the cavities
in the organic bodies, however minute, that happened to be

among

AND STRUCTURE OF THE BELEMNITE. 417

among it. Then follow the other operations of Hutron ; the
transference of the strata from the bottom of the sea to the
surface of the dry land, which, we have already shown, is the
only hypothesis at all reconcileable to the high inclination of
the chalk strata. It may be asked, if this chalk had undergone
a degree of heat capable of fusing it, what has become of the
crystallisation that must have followed that operation ? for, ex-
cepting in the cavities of the flint, where we sometimes disco-
ver some small crystallisations of quartz, and occasionally in
the limestone, a few cotemporaneous veins of calcareous-spar,
neither the flint, nor the limestone they rest in, present any
trace of crystalline arrangement; the texture is homogeneous
throughout, and, in general, extremely uniform. But we have
many such anomalies in nature ; the base of many of the trap-
rocks presents as little the appearance of crystallisation as even
the softest chalk, and yet it is now admitted, even by the pu-
pils of the Freyberg School, to be of igneous formation ; and
the circumstance which Sir H. Enceriexp mentions, of the
flints being sometimes found maintaining externally their
usual shape, but being, in reality, sometimes reduced to an ab-
solute impalpable powder in situ, which he attributes to the
severe concussion which altered the position of the chalk stra-
ta, we might adduce as; an argument for this rapid cooling ;
for to what does his description of these crushed flints more

nearly assimilate itself than to the state of unannealed glass ?
Nor does this idea of fusion oppose itself to the theory of
Professor Bucxuanp. I will still concede the possibility of an
organic origin to flint; but I will suppose it to have been a
marine organisation, and that the objects, like my fossils, had
been embarrassed in the seam of siliceous deposition, and be-
ing probably charged with siliceous sand, the silex has formed
round them, as nuclei, and, in the progress of assuming their
362 new

418 ON THE FORMATION OF THE CHALK STRATA, &c.

new shape, produced the alcyonic flints along with the tube-
rose masses we meet with. It may be observed, that these
alcyonia occur only in certain districts, and generally among
that immense mass of loose detritus * with which a large por-
tion of our southern counties are covered,—the remains, no
doubt, of chalk strata, which were probably demolished during
the great exertion of raising them from the bottom of the
ocean to the surface of dry land. These alcyonia, and other
zoophytic remains, afford strong corroborative proof of the ori-
ginal site of the flint, and not a single observation we are ac-
quainted with tends to subvert that fact. Nothing which
could have existed on the surface of the earth has ever been
found in chalk ; and so perfect are the remains which are oc-
casionally found in it, that there is reason to conclude, that, in
many instances, they could not have been long deprived of
life. In what state the ocean was at the time it contained in
solution the strata we have now been treating of, it is not my
intention to investigate ; it is one of those hidden mysteries of
the All-powerful Creator which we must be content to consi-
der as beyond the reach of human investigation.

To contemplate and to admire the works of Nature, is a
field open and patent to us all; and surely the order, the beau-
ty, and the simplicity of every thing we meet with, are calcu-
lated to impress the thoughtful mind, with an humble and re-
spectful admiration of the Almighty Power which is every
where displayed, together with a true sense of our own igno-
rance and deficiency, in all that appertains to the undefinable
wisdom we trace, throughout every department of the natural
world.

* T learnt from Mr Hopexty, that they had recently been found in situ in the
vicinity of Lewis.

XXIX.

XXIX.—On a Submarine Forest in the Frith of Tay, with
Observations on the formation of Submarine Forests in
general. By Joun Fiemine, D. D. F. RB. S. Edin.

(Read June 17. 1822.)

6 title which I have given to this paper, is, perhaps,
faulty, and apt to lead the imagination to expect a description
of the various forms of those sea-weeds which clothe the chan-
nel of the deep ;—the arrangement of the species, as depend-
ing on the soil and depth of water, the food which they yield
to the various creatures that browse upon them, and the pro-
tection they afford to such as take refuge among their leaves
and branches. Very different, however, is the scene which I
propose to describe,—a bed of peat-moss, covered by the sea
at every full tide, but indicating, by the appearances which it
exhibits, that its present low level is different from its origi-
nal position. In other words, it is a geological phenomenon,
occurring in the Frith of Tay, similar to the one observed

‘on the Lincolnshire coast, which, in 1796, was examined by

the late Sir Josrrs Banxs and Dr JosepH Correa pr Serra,
and described by the latter in the Transactions of the Royal
Society of London for 1799, p. 145, under the title, “ On a

Sub-

420 ON A SUBMARINE FOREST IN THE FRITH OF TAY.

- Submarine Forest, on the East Coast of England.” I venture
to prefix the same title to this paper, which I now offer to
the consideration of the Royal Society of Edinburgh, aware of
its impropriety, but urged by the wish to connect similar phe-
nomena by the common terms employed in their description.

The bed of peat to be described, and now dignified by the
title of a Submarine Forest, occurs on the south bank of the
Frith of Tay, and has been observed in detached portions on
the west side of Flisk Beach, to the extent of nearly three
miles, and on the east side, upwards of seven miles. At this
particular place, to which the following observations chiefly ap-
ply, it rests upon a bed of clay of unknown depth. This clay
is of a grey colour, much mixed with mica, and in some places
with grains of quartz, and resembles the Carse ground on the
opposite side of the Frith, or the contents of the sand-banks
which obstruct its channel. The upper portion of this clay
has been penetrated by numerous roots, which are now chan-
ged into peat, and some of them even into iron-pyrites. The
surface of this bed is horizontal, and situate nearly on a level
with low water-mark. In this respect, however, it varies
a little in different places. The peat-bed occurs immediately
above this clay. It consists of the remains of the leaves,
stems and roots of various common plants, of the natural or-
ders Equisetaceze, Gramineze and Cyperacez, mixed with
roots, leaves, and branches of birch, hazel, and probably also
alder. Hazel-nuts, destitute of kernel, are of frequent occur-
rence. All these vegetable remains are much depressed or
flattened, where they occur in a horizontal position, but, where
vertical, they retain their original rounded form. The peat
can be easily separated into thin layers, the surface of each co-
vered with leaves. The lowest portion of this peat is of a
browner colour than the superior layers; the texture likewise is

more

ON A SUBMARINE FOREST IN THE FRITH OF TAY. 42]

4 ¢
more compact, and the vegetable remains more obliterated.
The peat contains a good deal of earthy matter.

The surface of this bed of peat is nowhere (that I have de-
tected) covered by any alluvial stratum, nor does it occur at a
higher level than four or five feet below high water-mark.
Towards the shore it seems to be cut off by the old red allu-
vial clay, on which the newer grey, or carse clay also rests.

The only circumstance of much interest, in reference to
this peat-bed, remains to be stated. Upon its surface may be
perceived the stumps of trees, with the roots attached, and evi-
dently occupying the position in which they formerly grew ; as
the roots are observed to spread, subdivide, and penetrate the
bed in their usual natural manner. I have counted at one time,
after a favourable tide had cleared away all silt and gravel from
the surface, upwards of a score of these roots, situate at unequal
distances from one another, but all, by the position and ar-
rangement of their roots, demonstrating that such had been,
while growing, their original situation. To prevent any suspi-
cion from arising, that I may have been deceived on this subject,
I may state, that the scene, situate but a few hundred yards
from my dwelling, has been examined repeatedly, and under
different circumstances, and several friends who have visited
the spot, have appeared satisfied of the accuracy of my conclu-
sions. ‘I may mention the names of two of these, Mr Nerr
and Mr Batp, both members of this Society, and well quali-
fied, by habits of observation, to form a correct opinion on the
subject. Many of these trunks and roots occur from eight to
ten feet below high-water mark.

~ Ifowe’ assume, therefore, that the roots of these trees are in
their natural position, with respect to the bed which now sup-
ports them; are’ we warranted to conclude that they grew
on a surface ten feet lower than the high water-mark, but
before that surface was exposed to the periodical inunda-

tions

422 ON A SUBMARINE FOREST IN THE FRITH OF TAY.

tions of the tide? Every cavity, in this climate, situate at a
lower level than that of the sea, is invariably filled with water,
and in a condition hostile to the growth of trees, until its sur-
face has been elevated, by the washing in of mud, or the
growth of peat, to a position at least equal to the ordinary
rise of the tide. Since these trees could not, therefore, have
grown in an inland valley so far below the rise of the tide,
even where the sea was excluded, we must draw the conclu-
sion, that the surface on which these trees grew, was, at the
period of their growth, at least ten feet higher, in relation to
the sea, than at present; and to account for this remarkable
change, we must adopt one of the following suppositions :—
Either that the sea has risen ten feet, and overflowed that sur-
face which was formerly beyond its reach; or, that the ground
supporting these trees has sunk to the same extent.

The first of these suppositions, viz. A permanent rising of
the sea, has not been resorted to by any of those writers whom
we have had an opportunity of consulting. Indeed it is con-
trary to those known laws which regulate the movements of
the ocean, and receives no support from any circumstances
which have been observed on the maritime shores of this
country.

If, then, we abandon the idea that the sea has gained an
elevation of its level, and adopt the other supposition, viz.
That the peat-bed has sunk, so as now to be ten feet lower
than when the trees grew upon its surface, we advance a step
nearer the object at which we aim. It still remains, however,
to be determined, what those causes were, which operated in
depressing the surface of this bed, and enabling the waves to
pass over that soil which was formerly so much beyond their
influence, as to be fit for the support of the hazel and the birch
tree. erie

The

ea

ON A SUBMARINE FOREST IN THE FRITH OF TAY. 423

_ The first method of explaining the phenomenon likely to pre-
sent itself, , especially where the bed is limited in extent, is by
supposing | that the substratum, having lost its adhesion to the
bed on which it rested, by the percolation of water, and the
exposure of the side next the sea, moved down an inclined
plane into deep water, carrying along with it the upper layer
of vegetable matter, and the trees growing upon its surface.
Such occurrences have taken place in several inland bogs,
both in Scotland and Ireland, which have moved out of their
positions to a lower level. The extent, however, of this bed, and
the horizontality of its layers, prevent us from considering its
present depressed position as having been produced by any
sliding of this kind. Neither hath it arisen from the washing
away of the soft matter on which the bed supporting the trees
rested, for the clay still remains, and at the line of junction
is much incorporated with the peat.

This washing away of the subsoil, however, has been resorted
to by Mr Warr of Skail, to explain the conditions ofa submarine
forest on the west coast of Orkney. It occurred to him “ that
this bed of moss and trees has arrived at its present level
“ (so as to be covered, during the flood-tide, to the depth of
“ at least fifteen feet of water), in consequence of the removal
“ of a bank of earth, at least eighteen feet deep, which has
“ been washed gradually away, by the water of the Loch of
“ Skaill oozing along the rocks upon which it rested, and
“upon which the mass of leaves now rests, held together
“ by the fibres of the roots of the trees.” See Edin-
burgh Philosophical Journal, vol. iii. p. 101. This explana-
tion, however, is liable to very strong objections. It is not
probable, that, on the stormy coast of the west side of Orkney,
where the rocks themselves yield to the fury of the waves, and
where the top of every cliff is a heap of ruins, a mass of earth,

VOL. IX. P. II. 34 eighteen

424 ON A SUBMARINE FOREST IN THE FRITH OF TAY.

eighteen feet in thickness, would be permitted to. remain, un-
til washed away by the slow force of percolating fresh water,
or that a continuous bed of peat, of nearly an acre in extent,
would be spared from destruction, and suffered to settle peace-
fully, in the Bay of Skaill, so as to be covered at flood-tide
with fifteen feet of water.

If we have no reason to doubt that this Tay-bed was trans-
ported to its present situation, in what manner has it reached
its present level ? Two solutions of this curious question have
been offered, as connected with similar occurrences, by emi-
nent individuals, Dr Boruase, Dr J. Correa pr Serra, and
Professor PLayrair.

Dr Bortase, who, in 1757, observed a submarine forest at
Mount’s Bay, Cornwall, covered at full tide with twelve feet
of water, considered the depression of the bed, which support-
ed the trees, and still contained their roots im situ, as having
arisen from subsidence of the ground, produced by earth-
quakes, or, to state it in his own words, “ that there has been
“ a subsidence of the sea-shore hereabouts, is hinted in my
« letter to you, p. 92; and the different levels and tendencies
‘«¢ which we observed in the positions of the trees we found,
“ afford us some material inferences as to the degree and ine-
“ qualities of such subsidences in general ; as the age in which
“ this subsidence happened (near 1000 years since at least),
“ may convince us, that when earthquakes happen, it is well
“ for the country that they are attended with subsidences ;
“ for then the ground settles, and the inflammable matter,
“ which occasioned the earthquake, has no longer room to
“ spread, unite and recruit its forces, so as to create frequent
*“ and subsequent earthquakes ; whereas, where there are
“ earthquakes without proportional, subsidences, there the ca-
verns and ducts under ground remaining open and unchoak-

“ ed,

al
ra

ON A SUBMARINE FOREST IN THE FRITH OF TAY. 425

“© ed, the same cause which occasioned the first has room to
“ revive, and renew its struggles, and to repeat its desolations
“and terrors; which is most probably the case of Lisbon.”
Phil. Trans. 1757, p. 52.

The views of Dr Bortass, in reference to this depression of
the ground, in consequence of earthquakes, was evidently in-
fluenced by the curious observations which he had formerly
made on the subsidence of some places at the Scilly Islands,
as stated, Phil. Trans. vol. xtvui. p. 62; and other observers
may be led to form the same opinion, especially if the sin-
gular sinking of the cliff at Folkstone, about forty feet, even in
the absence of an earthquake, be taken in consideration. See
Phil. Trans. 1786, p. 220.

Dr Correa pz Serra also ascribes the depressed position
of the submarine forest of Lincolnshire to the force of sub-
sidence, aided by the sudden action of earthquakes. “ There
“is a force of subsidence (he says), particularly in soft’
“ ground, which, being a natural consequence of gravity, slow-
** ly, though perpetually operating, has its action sometimes
““ quickened and rendered sudden by extraneous causes, for
“instance, by earthquakes.” “ This force of subsidence, sud-
“« denly acting by means of some earthquake, seems to me the
“most probable cause to which the actual submarine situa-
“ tion of the forest we are speaking of may be ascribed. It
“ affords a simple easy explanation of the matter; its proba-
“ bility is supported by numberless instances of similar
events.” Phil. Trans. 1799.

Professor PLayrarr, when contemplating the phenomena of
the Lincolnshire submarine forest, rejected the explanation
offered by Dr Corrra pr Serra, and availed himself of some
of the ‘peculiar assumptions of the Huttonian Theory of the
Earth. “ The subsidence (he says) however, is not here

3H 2 “ understood

a
.

426 ON A SUBMARINE FOREST IN THE FRITH OF TAY.

understood to arise from the mere yielding of some of the
strata immediately underneath, but is conceived to be a part
of that geological system of alternate depression and eleva-
“ tion of the surface, which probably extends to the whole mi-
“ neral kingdom. To reconcile all the different facts, I should
“ be tempted to think, that the forest which once covered
“ Lincolnshire, was immersed under the sea by the subsidence
of the land to a great depth, and at a period considerably
remote ; that when so immersed, it was covered over with
“ the bed of clay which now lies upon it, by deposition from
“ the sea, and the washing down of earth from the land ; that
“ it has emerged from this great depth till a part of it has be-
“ come dry land; but that it is now sinking again, if the tra-
“ dition of the country deserves any credit ; that the part of
it in the sea is deeper under water at present than it was a
“few years ago.” llustrations of the Huttonian Theory,
p. 453.

A careful examination of these conjectures, which had been
offered to account for the phenomena of submarine forests,
soon convinced me that the subject was still imperfectly un-
derstood. Under this impression, I endeavoured to become
possessed of all the conditions of the problem, and now ven-
ture to offer a solution. The opinion which I have been led
to form has been entertained for some years, and stated to se-
veral friends, without an objection having presented itself.

If we suppose a lake situate near the sea-shore, and having
its outlet elevated a few feet above the rise of the tide, we
have the first condition requisite for the production of a sub-
marine forest.

If we now suppose, that, by means of mud carried in by
rivulets, and the growth of aquatic plants, this lake has be-

come

ON A SUBMARINE FOREST IN THE FRITH OF TAY. 427

come a marsh, and a stratum of vegetable matter formed on
the surface, of sufficient density to support trees, we arrive at
the second condition which is requisite. This state of a
marsh, formerly a lake, is of common occurrence, more espe-
cially where the surrounding grounds are high, and covered
with soil, for in this case the rain washes down earthy parti-
cles, and, by spreading them on the grassy surface, renders it a
more suitable soil for the growth of trees.

In this second condition, all the strata below the outlet of
the marsh are kept constantly wet, or in a semifluid state.
The force of ordinary subsidence, aided by occasional earth-
quakes, may render the whole tolerably compact ; yet the quan-
tity of water necessarily present, will prevent any thing like
the degree of condensation of ordinary alluvial land or soil
from taking place.

Suppose a marsh in this condition to have the level of its
outlet lowered, or rather, to have its seaward barrier removed
(an occurrence which many circumstances induce us to believe
to have happened frequently both on the east and west coasts
of this country, where submarine forests are not of rare occur-
rence), what consequences would follow ? The extremities of the
strata now exposed to the sea, would at every ebb-tide be left
dry, to a depth equal to the fall of the tide. Much water, for-
merly prevented from escaping by the altitude of the outlet,
would now ooze out from the moist beds, and the subsiding
force would act more powerfully in the absence of the water
which filled every pore. All the strata above low water-mark
would thus collapse, and the surface of the marsh, instead of
remaining at its original height, would sink below the level of
the sea. But the escape of the water from the strata would
not, in such circumstances, be confined to the beds situate
above the low water-line. Even those occupying a position

considerably

428 ON A SUBMARINE FOREST IN THE FRITH OF TAY.

considerably lower, would be influenced by the change ; for
the water even in such would be squeezed out, in conse-
quence of the pressure of all the matter of the strata above
the low water-mark, exerted during every ebb, in the expul-
sion of the water at the lowest level, thus permitting the sub-
sidence of the strata to take place even to the lowest beds of
the morass.

In consequence of this drainage, produced by the ebbing of
the tide on those marshes, the original barriers of which have
been destroyed, there is no difficulty in accounting for the de-
pression of the surface of a marsh many feet lower than its ori-
' ginal level, nor in explaining the fact that Neptune now tri-
umphs where Sylvanus reigned, and that the sprightly Nereids
now occupy the dwellings of their sister Naids.

The same explanation, now offered to account for the sub-
marine forest of the Tay, seems equally applicable to those of
Mount’s Bay, Lincolnshire, and Orkney. It is warranted by
the effects which we have observed to have taken place in differ-
ent districts of Scotland, from the artificial drainage of marshes
which had formerly been lakes, and which were in a condition
of surface fit for the growth both of willows and alders. In some
cases, where the outlet of the marsh has been lowered perhaps
ten feet, and a ditch at this new level opened through the mid-
dle of the ground, an expectation has been formed that the ori-
ginal surface would be drained of all its moisture, and brought
into an arable condition. A season, however, has scarcely elap-
sed, before this deep ditch has become shallow, not by the silting
up of the bottom, but by the subsidence of the neighbouring
matter, in consequence of the abstraction of the water; and
the ground which was expected to become fit for yielding crops
of grain, has returned to a condition better suited to the growth

of

ON A SUBMARINE FOREST IN THE FRITH OF TAY. 429

of rushes. No provision in these cases had been made for
the effect of subsidence.

Before concluding this paper, I may take notice of a few
facts which seem to have some interest in a geological point
of view.

1. One effect of the subsidence to which I have here alluded,
is the complanation of all the vegetable remains which oc-
cur in a horizontal position, or parallel with the surface of the
bed of peat ; while those situate vertically retain their cylin-
drical shape. The vegetable remains, so common in the
strata accompanying coal in this country, exhibit the same
appearances in similar circumstances, and lead to the con-
clusion, that the matter of the strata, at the period of depo-
sition, was in such’a condition as to admit of the mechanical
effects of subsidence taking place.

2. In the examination of the vegetable remains in this bed
of peat, and of others which have been investigated, I have
been led to conclude (contrary to the commonly received opi-
nion*), that’ many of the supposed stems of reeds which
oceur in a petrified state, are in fact roots. These roots, or
rather subterranean stems, such as the Arundo colorata and
phragmites, Menyanthes trifoliata, and many other marsh
plants exhibit, frequently occur in beds of peat, in a dead
state, and exhibit their peculiar characters, when but few
traces of the stems to which they belonged can be detect-
ed.

3. Several

* See Parxrnson’s Organic Remains, vol. i, p. 455,

430 ON A SUBMARINE FOREST IN THE FRITH OF TAY.

3. Several changes of a chemical kind have already taken
place in this stratum of peat. The fibrous structure of much
of the vegetable matter is obliterated, small portions of the
reeds, and even of the wood, are so changed as to resemble
wood-coal ;—changes these, which plainly intimate, that a
process is going on, by which, in time, that which is now peat
may become coal. In the crevices of some portions of the
wood I have detected thin crusts of the blue phosphat of iron.
It is rather singular to have found some of the roots in the
soft clay changed into iron-pyrites. This change has chiefly
taken place in the bark, and in such cases the wood and pith
are wanting. In one example, however, the pith remained,
and had likewise been converted into pyrites. In many cases
the clay is full of tubular cavities, the remains of the spaces
which the roots or stems of plants once occupied. The walls
of these cavities are usually of a darker colour, and firmer tex-
ture, than the surrounding matter, and have evidently under-
gone some change, in consequence of the decomposition of
the vegetable matter. In some cases, the epidermis of the
plant remains in contact with the surrounding clay, while
the matter of the interior has disappeared. Into these cavi-
ties the clayey matter enters slowly, and fills the mould which
the decomposition of the plant has prepared. This may be

regarded as a process similar to the one which has taken place .

in those vegetable petrifactions so common in the argillace-
ous and arenaceous beds of the coal-formation, in which slate-
clay, clay-ironstone and sandstone, are exhibited under the
external forms of plants.

Should these observations appear interesting or satisfactory,
I shall feel disposed to transmit, at no distant period, the re-
sult

ee

ON A SUBMARINE FOREST IN THE FRITH OF TAY. 431

sult of some observations “ On the present level of the Carse
of Gowrie, in reference to the Frith of Tay ;” and likewise
some remarks on “ the Truncated Sand-hills and Deep Basins,
which occur between Leuchars and Wormit Bay in Fife-
shire.”

Manse or F et
15th June 1822.

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rage. sat ae

XXX.—Description of a Monochromatic Lamp for Microsco-
pical purposes, §c. with Remarks on the Absorption of the
Prismatic Rays by coloured Media. By Davin Brewster,
LL. D. F.R. S$. Lonp. & Sec. R. S. Eni.

(Read April 15. 1822. )

In a Paper on Vision through coloured Glasses, which I had
lately the honour of submitting to the Society *, I pointed out
the advantages of coloured media in Microscopical and Teles-
copical observations. Having experienced the great utility of
Green and Red lenses, in developing vegetable structures that
required to be examined with high powers, I was anxious to
derive from this new principle all the advantages which it ap-
peared to possess. In attempting to do this, it became necessary
to ascertain the power of giving distinct vision, which belonged
to each separate colour of the spectrum, and though I had
stated in my former paper, “ that it was difficult to discover
*“ any reason why one coloured medium should be preferred
“ to another, provided each of them transmits equal quantities
“ of homogeneous light ;” yet it was desirable to put this
theoretical opinion to the test of direct experiment. Sir Wit-
tam Herscuet + had long ago investigated this point in refe-
rence to the use of coloured media for solar observations, and
had concluded that every colour of the spectrum possessed the

312 / same

_ * See the Edinburgh Philosophical Journal, vol. vi. p. 102.
“+ Philosophical Transactions, 1800. .

_434 ON A MONOCHROMATIC LAMP FOR MICROSCOrES, &c.

same power of giving distinct vision ; but his method of observa-
tion, which consisted in viewing through a microscope a Nail
illuminated in succession with each of the colours of the prism,
was by no means calculated to give definite results, and there-
fore left the question in all its uncertainty,

In order to obtain precise indications, which were not ca-
pable of being misinterpreted, when applied to practical pur-
poses, I formed a spectrum from a luminous disc, by means of
a prism of a highly dispersing substance, and with a large re-
fracting angle. I then examined this spectrum through a great
variety of coloured media, both solid and fluid, and marked
the size and shape of the image into which it was converted.
The perfection of this image, or its narrowness in the direction
of the length of the spectrum, became a precise and unequivo-
cal test of the fitness for distinct vision which belonged to the
light out of which it was formed.

_ By this method of observation, I found that a distinct image
of the luminous disc could not be obtained either by produ-
cing a Blue or a Green image, and that it was only in the Red
portion of the spectrum that such an effect was likely to be ob-
tained. In the use of purple glasses, I observed that the
middle portion of the Red space was absorbed before the two
extreme portions, so that instead of one Red image there were
two, quite separate, and tolerably distinct. By increasing,
however, the thickness of the plate, the most refrangible red
image was absorbed, and the least refrangible one left in a
state of the most perfect distinctness. Although I had now
determined the part of the spectrum that was best fitted for
giving perfect vision, yet the quantity of light extinguished
before the insulation of the extreme red ray was affected, was
so great as to render the determination of little practical utili-
ty, excepting in cases where the outline of an object was to be
observed. Had it been possible to insulate the most luminous
rays of the spectrum as perfectly as the extreme Red ones, the

advantage

AND ON THE ABSORPTION OF THE PRISMATIC COLOURS. 435

advantage would have been of very considerable amount ; but I
have found this quite impracticable, and I venture to say, that
the separation of homogeneous green or homogeneous yellow
light, of any considerable intensity, cannot be effected by any
coloured media with which we are at present acquainted.

Abandoning, therefore, all hopes of obtaining from colour-
ed media any farther improvement upon the microscope than
what I had formerly announced, it occurred to me, that the
object which I had in view might be obtained, if I could pro-
cure, from the combustion of inflammable substances, a homo-
geneous flame for illuminating microscopic objects.

It had long been known, that a great quantity of homoge-
neous yellow light was created by placing salt or nitre in the
white flame of a candle, or in the blue and white flame of burn-
ing alcohol *. A light, however, generated in this manner,
was more fitted for a casual experiment, than for a permanent
source of illumination ; and as insalubrious vapours are disen-
gaged during the combustion of these salts, I did not avail my-
self of this method of obtaining yellow light.

After numerous experiments, attended with much trouble
and disappointment, I found that almost all bodies in which
the combustion was imperfect, such as paper, linen, cotton, &c.
gave a light in which the homogeneous yellow rays predomi-
nated ;—that the quantity of yellow light increased with the
humidity of these bodies ;—and that a great proportion of the
same light was generated, when various flames were urged me-
chanically by a blowpipe or a pair of bellows.

As the yellow rays seemed to be the product of an imper-
fect combustion, I conceived that alcohol diluted with water

would

* Edinburgh Physical and Literary Essays, vol. ii. p. 34.; and Dr Tuomas
Youne’s Nat. Phil. vol. i. p. 488. Mr Hexscuet informs me, that sulphur in a
certain stage of its combustion produces a —a yellow light.

436 ON A MONOCHROMATIC LAMP FOR MICROSCOPES, &c.

would produce them in greater abundance than when it was in
a state of purity, and upon making the experiment, I found it
to succeed beyond my most sanguine expectations. The whole
of the flame, with the exception of a small portion of blue
light, was a fine homogeneous yel/ow, which, when analysed by
the prism, exhibited faint traces of green and blue, but not a
single ray of red or orange light. The green and blue rays which
accompanied the yellow flame, had comparatively so little in-
tensity, that they disappeared in the processes of illuminating
and magnifying the object under examination ; and, even if
they had existed in greater abundance, it was quite easy to
absorb them at once by the intervention of a plate of the palest
yellow glass, and thus render the lamp perfectly monochroma-
tic.

From many experiments on the combustion of diluted alco-
hol, I found that the discharge of yellow light depended great-
ly on the nature of the wick, and on the rapidity with which
the fluid was converted into vapour. <A piece of sponge, with a
number of projecting points, answered the purpose of a wick
better than any other substance, and the extrication of the yellow
light became more copious, by placing a common spirit-lamp
below the burner of the other. In order to obtain a very
strong light for occasional purposes, I connected with the top
of the burner a frame of wire-gauze, which, by moving vertical-
ly round a hinge, or by a motion to one side, could be placed
in a horizontal position about half an inch above the wick.
As soon as it had become red-hot, it was made to descend into
contact with the sponge, when it converted the alcohol rapidly

into vapour, and produced an abundant discharge of yellow
light. See Plate X XVII. Fig. 1.
_Ifa permanently strong light is required, I find it preferable
to dispense entirely with the use of the wick, and to allow the
diluted alcohol to descend slowly from the rim into the bot-

tom

AND ON THE ABSORPTION OF THE PRISMATIC COLOURS. 437

tom of a concave dish of platinum, kept very hot by a spirit-
lamp placed beneath it. The bottom of the dish is made with
a number of projecting eminences, in order that the film of fluid
which rests upon it may be exposed at many points to the action
of the heated surface. See Fig. 2. After the lamp has burned
for some time, a portion of unevaporated water, mixed with a
small quantity of alcohol, will remain at the bottom of the
dish, in a state unfit for combustion. This water may be taken
up by a sponge, or it might be prevented from accumulating,
by having a fountain of pure alcohol, from which the exhaust-
ed strength of the diluted fluid could be renewed.

. The Monochromatic Lamp being thus completed, I lost no
time in applying it to the illumination of Microscopic objects.
The effect which it produced far exceeded my expectations.
The images of the most minute vegetable structures were pre-
cise and distinct, and the vision in every respect more perfect
than it could have been, had all the lenses of the microscope
been made completely achromatic by the most skilful artist.
The errors which arise from the different refrangibility of
light, being removed from microscopical observations, I was
enabled to enlarge considerably the aperture of the object-
glass, till the image became sensibly affected by the errors of
spherical aberration. In order to diminish these as much as pos-
sible, the object-glass should consist of an annular portion of the
lens that gives a minimum spherical aberration, and while its
surfaces are nicely centered, their common axis should be ad-
justed so as to coincide accurately with that of the other lenses.

‘The optician, however, will probably be induced to exert his

ingenuity in the formation of elliptical and hyperbolical lenses,
which, since the days of Descartes and Huycens, have exist-
ed only in optical theories, and thus remove the only imper-

fection which still attaches to the microscope.

Independent

438 ON A MONOCHROMATIC LAMP FOR Microscores, &c,

Independent of its use in microscopical observations, the
Monochromatic Lamp will find an extensive application in va-
rious branches of the arts and sciences. In certain cases of
imperfect vision, where a number of coloured images are
formed by the separation of the fibres of the crystalline lens,
a homogeneous light will improve the vision, by removing
the prismatic tints, which obliterate the principal image. In
illuminating the wires of Transit Instruments and Micro-
meters ;—in graduating the limbs of divided Instruments,
which is generally done by candle-light ;—in reading off the
same divisions in fixed observatories ;—in forming signals in
Trigonometrical Surveys ;—in obtaining correct and uniform
measures of Refractive Powers ;—in measuring the separation
of the two pencils in Doubly-refracting Crystals ;—in deter-
mining the focal lengths of lenses ;—in observing various op-
tical phenomena, where the light is decomposed ;—in these,
and, in general, in all delicate works, where correct vision is
essential, the employment of a homogeneous flame will be
found to confer the most signal benefits.

Having thus described the construction and application of the
Monochromatic Lamp, I shall now proceed to give a short ac-
-count of the experiments which I was led to make, during this
enquiry, on the modification of the prismatic spectrum by the
action of differently coloured media.
These experiments relate to three different points :
1st, To the manner in which coloured media absorb the dif-
ferent portions of the prismatic spectrum.
2d, To the influence of heat in modifying this absorbent
power ; and,
3d, To the determination of the question, whether or not
yellow light has a separate and independent existence
in the solar rays.

1.. Dr

AND ON THE ABSORPTION OF THE PRISMATIC COLOURS. 439

‘1. Dr Youne (Phil. Trans. 1803) has long ago remarked, that
the light transmitted by a specimen of Blue glass exhibited two
red spaces when analysed by a prism ; but he does not mention
their relative intensities. Among the various kinds of blue glass
which I have examined, I have found one, which, like Dr
Youne’s, leaves two red spaces, or rather an orange-red and a
red space, the rays which belonged to the intermediate portion
having been entirely absorbed, and the least refrangible of the
red spaces being more luminous than the other. In another
specimen, the interior orange-red image was absorbed along
with the middle one, and in a third specimen, the exterior
red image and the middle one were alone absorbed. In all
these glasses the absorbent power attacks also the green rays
adjacent to the red, and leaves a greenish-yellow image, sepa-
rated by a dark interval from the most refrangible green.
When light is reflected from the blue oxidated surface of steel,
the middle red space is completely absorbed, and there remains
only of the inner orange-red space, a few of the red rays that
border upon the green light. From these experiments it fol-
lows, that blue glass attacks the spectrum in several points at
the same time, and after absorbing all the middle rays, it leaves
only the extreme red, and the portions of the blue and violet
spaces which are contiguous. By increasing the thickness of
the glass, however, the violet is at last overpowered, and the
red alone remains. The very same phenomena are obtained
by fluid media of a blue colour. With some Blue glasses,
however, the red is overpowered before the violet. See F ig. 4.,
Nos. 2, 3, 4, 5.

In making a series of analogous experiments with Green me-
dia, I have found that they attack the spectrum at both ex-
tremities, but the blue end with more force than the red end.
By increasing the thickness of the glass, the blue and red light
gradually diminish, but it is extremely difficult to free the

"VOL. IX. P. IL. 3K green

440 ON. A MONOCHROMATIC LAMP FoR MicroscorEs, &c.

green image from these adhering tints. The sulphate of cop-
per, even in. thin laminze, exerts a very powerful action over
the red and violet extremities of the spectrum, See Fig. 4.
Nos. 6, 7, 8.

In examining the spectrum with Yellow glasses, the Violet,
Blue, and Green rays are absorbed in succession, and the red
and -yellowish-green remain untouched. By means of a very
thin plate of native yellow orpiment, the violet, and almost all
the Blue rays are absorbed, while the Red, and all the Green
are left.

Red glasses, like those which are Blue, do not attack the op-
posite extremity of the spectrum. They first absorb the blue
rays, then the violet, then the green and yellow; and by in-
creasing their thickness, the red itself finally disappears. A
red glass, with a slight tinge of yellow, absorbed with great avidi-
ty the blue and green that are adjacent to one another, leaving
the violet in full force, and also the green adjacent to the red,

2. In attempting to ascertain the influence of heat upon the
absorbing power of coloured media, I was surprised to ob-
serve that it produced opposite effects upon different glasses,
diminishing the absorbent power in one case, and increasing
it in another.

Having brought to a ed heat a piece of purple glass. that
absorbed the greater part of the Green, the Yellow and the in-
terior, or most refrangible Red, I held it before a, strong light,
and when. its red heat had disappeared, I observed that the
transparency of the glass was increased, and that it transmitted
freely the Green, the Yellow, and the interior Red, all of which
it had formerly in a great measure absorbed. This effect,
however, gradually disappeared, and it.recovered. its former
absorbent power when completely cold.

When. a yellowish-green Glass was heated in, a similar man-
ner, it lost its transparency almost entirely. In recovering its

green

AND ON THE ABSORPTION OF THE PRISMATIC CoLouRsS. 441

green colour, it passed through various shades of olive-green ;
but its tint, when cold, continued less green than it did before
the experiment. (A part of the glass had received in cooling
a polarising structure, and this part could be easily distinguish-
‘ed from the other part by a difference of tint.

A plate of deep-red glass, which gave a homogeneous red
image of the candle, became very opaque when heated, and
scarcely transmitted the light of the candle after its red heat
‘had subsided. It recovered, however, its transparency to a
certain degree, but when cold, it was more opaque than the
piece from which it was broken.

“8. As) it ‘has‘been concluded from Dr Wottasron’s experi-
ments on the prismatic spectrum, that it consists only of four co-
ours, Red, Green, Blue and Violet, that pure white light does not

contain any yellow rays ;—and that when yellow does appear
at ‘the boundary of a large white space seen through the prism,
itisa compound light, consisting of Green and Red rays *, it oc-
curred to me’ thatthe accuracy of these opinions might be. ex-
‘amined: by means of the absorbing media already mentioned.

I therefore formed.a very ‘brilliant spectrum, froma narrow
aperture placed:between’my eye and the sun, and by varying
the distanceof theprism from ‘the aperture, I obtained a spec-

trum exactly-similar to that-described by Dr Woriastow and
Dr Youne,'who has adopted and illustrated the opinions of his
friend-respecting the composition of white light.

Upon viewing this spectrum through:a glass, which absorbed
the Red)next the Green, ‘and «also ‘through »a -glass:which.ab-
sorbed, the Green next the Red, Iwas entitled:to expectithat
these portions of the spectrum would vanish; but» instead of
this taking place, the space from which these colours were ab-
sorbed was in both cases occupied by Yellow light, which was

3K 2 not

* Dr TxHomas Youxe’s Lectures on Natural Philosophy, vol. i. p. 138.

442 ON A MONOCHROMATIC LAMP FoR microscorgs, &c.

not only bright, but well defined in its boundaries. This dis-
tinct exhibition of the yellow space, established beyond a
doubt its existence in the spectrum, and may be considered as
proving, in a very convincing manner, that the Red and Green
spaces, at the place where they come in contact, consist of Red
and Green rays, respectively mixed with yellow rays of the
same refrangibility. The Yellow light, therefore, of the solar
rays, instead of occupying a separate place in the spectrum,
has its most refrangible rays mixed with green light of equal
refrangibility, and its Jeast refrangible rays mixed with red
light of equal refrangibility.

In order to ascertain whether or not the yellow homogene-
ous light produced by imperfect combustion, occupied the
same place in the spectrum with the yellow light, which re-
mains after the absorption of part of the red and green spaces,
I formed a spectrum like Dr Wotzasron’s, from the flame of a
candle, as shewn at AK, Plate XX VII. Fig. 3. I then put some
salt into the wick, for the purpose of producing a considerable
portion of yellow light, which affected principally the margin of
the upper and lower part of the flame, and I again observed the
spectrum, when I found that the yellow light occupied the posi-
tion at Bd, so as to cover a part both of the green and the red
space ; the part of the green space occupied by the yellow light,
being to that of the red spaces occupied by it nearly as 3 to 1.
From these experiments, we are entitled to conclude, not on-
ly that yellow light has an independent ewistence in the spec-
trum, when formed from any kind of white light ; but that the
prism is incapable of decomposing that part of the spectrum
which it occupies.

EXPLA-

Ate a

( 443. )

EXPLANATION OF PLATE XXVII.

Fig. 1. Represents one form of the Monochromatic Lamp, where A is the reser-
voir containing the diluted alcohol, which descends by the channel ABCD
to the broad wick B, which is generally made of sponge. A frame of
wire-gauze F moves round a hinge H, so that it can be brought over
the flame, and made to descend, when hot, upon the surface of the wick.
Excellent wicks may be made with concentric cylinders of thin mica, or

of platinum foil.

Fig. 2. Is another form of the Lamp, without a wick, in which the diluted al-
cohol is burned in a flat platinum or metallic dish MN, which may be
made to have a slight spontaneous oscillatory motion, for the purpose of
bringing the fluid over the heated projections of the platinum. A com-
mon spirit lamp OP, inclosed in a case, is placed below the platinum
dish MN, in order to produce sufficient heat for throwing off the vapour
from the diluted alcohol.

A chimney, or a cylinder, of pale yellow glass may be placed round the
flame, if it should be thought of any consequence to absorb the small por-
tion of blue light which accompanies the yellow flame:

Fig. 3. Represents the method of finding the position of the Yellow space in the
spectrum.

Fig. 4. Represents the various ways in which the prismatic spectrum is attacked
by the absorbent action of differently coloured glasses, as described in the
paper.

No. 1. Represents the prismatic spectrum as described by Dr Wollaston.
No. 2. Represents the effect produced by viewing the spectrum through a blue
glass, like that used by Dr Young. The spectrum is attacked at
se a,b,c; a portion of the middle of the Red space being destroyed at a,

: a portion of the Red and Green, disclosing the Yellow at 0, and a por-

tion of the Violet being destroyed at c.

No. 3. Shews the effect of a different kind of blue glass, which destroys the in-
ner portion of the Red space at a, a less portion of the Violet at c, and a
greater portion of the Green at b; the disclosed. Yellow being now of a
different hue.

No. 4. Shews the effect produced by the Blue glasses of No. 2. and No. 3. com-

ined. +The spectrum is now attacked at a fourth point, viz. the com-
mencement of the Blue space at c, and the Yellow is rendered less bril-
jiant. By increasing the thickness of these plates of blue glass, the
dingy Yellow part vanishes, then the Green, as in No. 5., then the
Blue, .

444

No.

No.

ox

=

. 10.

. 11.

» 12.

wales

. 14.
» 15.

EXPLANATION OF PLATE XXVII.

Blue, and, last of all, the Indigo; so that the combinations of Blue
glasses have now the effect of Red glasses.

Shews the effect of increasing the Blue glasses in No. 4. to a certain
thickness. as a

Shews the effect of a Sky-blue paste, which reflects: most copiously the
Blue light. The whole spectrum is destroyed excepting the extreme Red.

Represents the effect produced by a great thickness of Green glass. _

Sulphate of copper, which is bluish-green, both in. the solid state and m
the state of a solution, leaves unabsorbed a great quantity of Yellow
light, which may be rendered tolerably homogeneous by means of a
pale Yellow glass. The figure shews its effect in attacking the Red and
Violet ends of the spectrum, a portion of blue and red being left.

Shews the effect of a greater thickness of Sulphate of copper, in absorbing
all the Red, and leaving a Cramiaksy with an adhering ne of
blue light,

Shews the influence of a thick plate of Vellowish-red glass, in absorbing
all the blue, and part of the green, leaving the violet slightly affected.
Represents the singular effect produced by a solution of Lake, There
are here two. greens, and an effect is produced at the boundary of the

red and.green space.

Represents the effect of a thick piece of fine Red glass, coloured with gold,
and also of a piece of stained glass, which I found in the Abbey of
Konigsfelden, in the canton of Berne. The same effect is produced by
common red ink, and. by a solution of beet-root in vinegar.

Shews the action of an opaline milky-white glass upon the most refran-
gible half of the spectrum.

Shews the effect ofa certain thickness of native yellow.orpiment.

Shews the effect of ‘a red. glass combined with yellowish-green and bluish-
green glasses. 'The yellow is much, more, copious. and briiliant when
the red glass is combined with a certain thickness of sulphate of cop-

per, but it is then fringed with a. narrow margin of, Red on one side,, ;

and of Green on the other.

No. 16. By combining with the same red.glass a thicker plate.of sulphate of cop-

per, the yellow becomes green; and by ‘a,thicker plate-stil, the colour
beccmes blue, as in the figure.

XXXL

? —

PLATE Xxv0 . Eng#for the Edin” Royal Soo. Tran. Vol IX P +44

}

=,

oe"

Fig. +.

We 9 ... W? 10. WY IE: W? 12

wv? 18. Neu. cS SOS ais:

WA Lizars Scalp

ee

XXXIL—On the Absorption of Light by Coloured Media, and
on the Colours of the Prismatic Spectrum exhibited by cer-
tain Flames; with an Account of a ready Mode of deter-
mining the absolute dispersive Power of any Medium, by
direct experiment. By J. F. W. Herscuez, Esa. F. R. 8S.

; Lonp. & Enry... Ina Letter to Dr Brewster.
. d

(Read November 18. 1822. )

My pear Sir, —

ks As I see by a notice in your Journal, No. 13., which has
just reached my hands, that your attention has been occupied
by the phenomena of Coloured Flames, and the Absorption of
Coloured Light by Diaphanous Bodies ; and that you have
been successful in the very. valuable discovery of a manageable-

flame, discharging a homogeneous yellow light of an inva-
riable character, I shall perhaps be excused, while the contents

of your paper are unknown to. me more particularly, for sta-

_ting-some phenomena which I have myself observed, relative

to this highly interesting department of physical optics.

2. In the course of my experiments in-1819, on’ the scale’

‘of tints developed by different erystals in polarised light, ha-

ving frequent occasion to measure the diameter of the rings of

different
2

446 ON THE ABSORPTION OF LIGHT BY COLOURED MEDIA,

different homogeneous colours, I naturally had recourse to the
prismatic spectrum ; but soon finding the extreme difficulty of
procuring a tolerably homogeneous ray by this means, owing
to the sun’s diameter, the irradiation of the sky, and the im-
perfections of prisms, not to speak of the mobility of the spec-
trum, being then unprovided with a heliostat, I began to study
the resources afforded by transparent coloured media, in hopes
that I might discover some, whose limits of transmission, either
singly or eee might be such as to allow the passage of
rays only within very narrow limits of refrangibility. In this
examination I immediately encountered the singular pheno-
mena, noticed, | believe, first by Dr Younc, of an almost to-
tal obliteration of some of the colours by certain glasses, while
others intermediate between, or sharply bordering on those
obliterated, appeared to be transmitted in all their brilliancy,
thus producing an image (when a narrow luminous line is
examined with a prism, and such a coloured glass), not con-
sisting of a broad band of gradually varying colour, but an as-
semblage of more or less sharply defined coloured streaks of
different breadths and colours, separated by intervals, in some
cases absolutely black,—in others only feebly illuminated.

This singularity g gave me strong hopes of success in the object
of my inquiries, and I was not sahally disappointed.

3, Among the first specimens of glass which occurred to me,
were a disc of bright ruby-red glass, from an ancient window,
and a quantity of deep-blue glass, with a sensible tinge of
purple, which is manufactured in large quantities for sugar-
basins, finger-glasses, &c., and is one of the most common
of the coloured glasses. The former permitted to pass almost
the whole red, and a considerable portion of the orange ; while, °

in

i

Ms PLATE XXvVIZ.

Eng" for the Reval Soe: Tran, Vol IX page #47.

Fig. 1. Fig. 2. Fig. 3. Fig. &.

AND ON THE COLOURS EXHIBITED BY CERTAIN FLAMES. 447

in strong lights, a sensible quantity of yellow, and even a
feeble trace of green, might be perceived. If we conceive the
abscissa RV, Plate XXVIII. Fig. 1. to represent the prisma-
tic spectrum, and erect an ordinate at every point, propor-
tional to the number of rays, out of any given quantity, of the
corresponding refrangibility the medium is capable of trans-
mitting, its extremity will have for its Jocus a curve of the
form royg, which, for brevity’s sake, I will call the type of
this medium; the type of a colourless medium being the
straight line MN, parallel to the abscissa.

4. Let ¢ be the thickness of any homogeneous medium, or
the number of colorific molecules, of equal absorbent powers,
traversed by a ray in its passage through it; and let C repre-
sent the intensity of a ray of any given refrangibility, at its
first intromission, y being the ratio of its intensity, after tra-
versing a thickness equal to unity, to its original intensity C.
Then will

C+C 4’ + &., or S {Cc}

from one end of the spectrum to the other, represent the tint
‘and intensity of the ray at its intromission, while its charac-
ter, after traversing the thickness ¢, will be

Cy + Cyt + Cy” + &, = S {Cy ‘

It would appear, at first sight, that the effect of doubling or
tripling the thickness of any coloured medium, would simply
be to increase the depth and intensity of the tint, but not to
alter its character. If a white object appear blue through a
blue glass, we should expect it to appear still bluer through
two, and yet more so through three such glasses. The above
formula shews, however, that this is so far from being the case,

VOL. IX. P. Il. 3. that

448 ON THE ABSORPTION OF LIGHT BY COLOURED MEDIA,

that the tint of the emergent pencil is essentially dependent
on the thickness of the medium, and that it is only from a
knowledge of the relative values of y, y’, &c. in the various
parts of the spectrum, that we can say, a priori, whether the
tint of a thick glass will retain any similarity to that of a thin
one of the same kind. It is evident that, y being necessarily a
fraction less than unity, the values of y', 7’ ‘, &c. willall diminish,
with an increase in that of t. Those terms, however, in which
y is smallest, will decrease most rapidly, and, however trifling
may be the difference in this respect, it is always possible to
render its effect sensible on the tint, by taking ¢ sufficiently
large. Thus the water of the Lake of Geneva is indigo-blue,
that of the Lake of Como emerald-green, when viewed through
a considerable thickness, though colourless in small quantities.
If (as is very common) the value of y should have two une-
qual mavima, in different parts of the spectrum, and if, at the
same time, the greater of these should happen to corres-
pond to a ray of feebler illuminating power than the less, the
tint, in small thicknesses of the medium, will (generally speak-
ing) be that of the lesser maximum, the greater vividness of
these rays giving them a predominance over the others, though
more numerous; but as this inequality of number increases ,
with the increase of thickness, the feebler rays will at length
begin to influence the tint, and finally obtain the predomi-
nance ; thus producing, in several cases, a complete change of
colour, not a little surprising to those who are ignorant of its
cause. Dr Tuomson’s muriated liquor (chloride of sulphur),
which is yellowish-green in very small thicknesses, and bright
red in considerable ones, is a case in point. A solution of
sap-green presents the same phenomenon yet more striking-
ly. Ifinclosed between glass-plates slightly inclined, so as to

form a thin wedge, its colour towards the edge will appear
emerald-

AND ON THE COLOURS EXHIBITED BY CERTAIN FLAMES. 449

emerald-green, and towards the back blood-red, passing in the
intermediate thicknesses through a kind of livid neutral tint.

5. The blue glass above mentioned exhibits this change of
tint in a very marked manner. When a piece of the thickness
0.042 inch was employed, it separated the red portion of the
spectrum into two; the least refracted being a well-defined
band of perfectly homogeneous and purely red light, and se-
parated from the other red by a band of considerable breadth,
and totally black. This latter red was nearly homogeneous ;
its tint, however, differing in no respect from the former, and
being free from the slightest tinge of orange. Its place in the
spectrum is such, that its most refracted limit exactly comes
up to that remarkable black line which Dr Wotuaston obser-
ved separating the red from the yellow in the solar spectrum.
A small sharp black line separated this red from the yellow,
which was a pretty-well defined band of great brilliancy and
purity of colour, of a breadth exceeding that of the first red,
and bounded on the green side by a dark, but not quite black
interval. The green itself was dull, and ill defined ; but the
blue and violet. seemed to be transmitted with very little loss.
The type of this glass is as in Fig. 2.

A double thickness (0,084 in.) obliterated the second red,
but left. the first unimpaired, The yellow was greatly en-
feebled,, and somewhat reduced in breadth, and terminated on
the side of the green. by a black band, equal in breadth to it-
self. The green also was extremely diminished, but the blue
less so, and the violet remained nearly as before. The curve,
Fig. 3., exhibits the type of this thickness of the glass. _Last-
ly, When. a great many. thicknesses of it were laid together,
the extreme red and the violet. only were transmitted, and. the
type assumed the character of Fig. 4.

31 2 The

450 ON THE ABSORPTION OF LIGHT BY COLOURED MEDIA,

The facility with which the extreme red ray is transmitted
by this glass, in comparison with the rays of intermediate re-
frangibility, produces a change in the general hue of the glass
corresponding to its thickness. In small thicknesses it ap-
pears purely blue; but as its thickness is increased, a‘purple
tinge comes on, which becomes more and more ruddy, and,
finally, passes to deep-red, a great thickness being, however,
required to produce this effect.

6. On the other hand, a glass of a rich ruddy purple was
found to have its type, as in Fig. 5. The curve 1 correspond-
ing to a thickness 0.065 in. ; 2 to a thickness 0.086; and 3, in
which the least refrangible rays are almost entirely obliterated,
to their sum. In consequence of this, the tint of the glass
loses its ruddy hue, by an increase of thickness, and passes to
a fine violet.

7. The extreme red light, transmitted with such facility by
the glass described in Art. 6., is copiously absorbed by this.
The species of light alluded to is remarkable, jirst, for its per-
fect homogeneity ; and, secondly, for its position in the spec-
trum. When the solar spectrum received on a white paper in
a darkened room, is viewed through a moderate thickness
(0.08) of that glass (of Art 6.) cemented to any red glass of a
tolerably pure colour, it will be seen reduced to a perfectly cir-
cular and well-defined image, of a deep-red colour. If a pin
be now stuck in the centre of the red circle, it will be found,
on removing the glass from the eye, to have been fixed in
what an ordinary observer would call the very farthest termina-
tion of the red rays, and a mark similarly made at its circum-
ference will appear to lie wholly without the spectrum among
the dispersed light which usually hangs about its edges. In

other

AND ON -THE COLOURS EXHIBITED BY CERTAIN FLAMES. 451

other words the red, thus insulated, is of too feeble an illumi-
nating power to affect the sight in the immediate vicinity of
the other more brilliant rays, aa only becomes visible when
they are extinguished, or greatly enfeebled. To an eye defended
by such a glass, vision, through a prism with the largest re-
fracting angle, is as sharp, and the outlines of minute objects
as free from nebulosity and indistinctness, as if the rays had
suffered no refraction. ‘These characters,—the absolute ho-
mogeneity of the rays,—their situation precisely at the least
refracted limit of the spectrum, and the facility with which
they may be insulated, render them of peculiar importance as
standards of comparison in optical experiments. I shall in fu-
ture always be understood to speak of these, when I use the
expression extreme red rays.

8. Almost analogous in its type to that of Figures 2, 3,
and 4., but differing from it in a higher degree of insulation
of the yellow rays, is a species common enough in ancient
windows. Its tint is a blue, much less vivid than the blue glass
above mentioned, and bordering rather on grey or slate co-
jour. A thickness 0.184 in. of this glass, is sufficient to pro-
duce a very sharp termination of the yellow band on the least
refrangible side, and almost to obliterate the green. The yel-
low portion of the spectrum is thus placed in the clearest evi-
dence. It is of great brightness, and by no means that almost
infinitesimal line which Dr Youne seems to have regarded it ;
its breadth being nearly ith of the interval between the red
and blue parts of the spectrum. By the aid of this glass,
I have succeeded in insulating a yellow ray of considerable
strength, cutting off the more refrangible end of the spectrum
by a yellow or light-brown glass, and the less by a bluish-green
one, and, though not quite homogeneous, having still an ad-

hering

452 ON THE ABSORPTION OF LIGHT BY COLOURED MEDIA,

hering fringe of green. It is quite sufficient for experiments of
ordinary delicacy.

9. It is needless to detail the numerous experiments I have
made with glasses of different shades ; but it may not be amiss
to mention in a general way, the effect of prismatic analysis
on the tints of most usual occurrence in coloured media. Red,
scarlet, orange, and brown coloured media, with all the shades
of yellow, such as glasses of the above-mentioned. hues, Port
wine, infusion of saffron, vegetable blues turned red by acids,
brandy, India soy, permuriate of iron, muriate of gold, &e. &c.
act by extinguishing the violet end of the spectrum with pecu-
liar energy, and their type has the general character of Fig. 1.
In consequence, they all become red by increase of thickness,
and some of them (as Port wine of a good colour), may be
used to insulate the extreme red in a high degree of purity
and abundance.

10. Among green media, we may distinguish those in which
the type has a maximum ordinate corresponding to some part
of the green rays (as in Fig, 6.), and whose hne, in conse-
quence, becomes more purely green by an increase of thick-
ness. -Of this kind are most green glasses, green solutions of
copper, nickel, &c. These absorb both the extremities of the
spectrum ; the red, with greater energy, if the tint verges. to
blue, but the violet if to a yellow. Besides these, however,
are to be remarked media in which the type has two maxima,
one corresponding to the red, and one to the green rays, as in
Fig. 7.. In most of these the green maximum is less than the
red, and in consequence the tint, on an increase of thickness,
passes from green, through a dirty neutral. brown, to red.
Among these spurious greens, the aqueous solution of sap-

green

AND ON -THE COLOURS EXHIBITED BY CERTAIN FLAMES. 453

green has already been noticed. The tincture extracted from
the petals of the common red peony ( Peonia officinalis ), by
a weak solution of carbonate of potash, is a yet more striking
- example of the same phenomenon, to which we may add the
dark-coloured liquid formed by impregnating a solution of sul-
phat of iron with nitrous gas, and various mixtures of red and
blue, or green media. In a green solution of manganesiate of
potash (Chameleon mineral), the maxima correspond likewise
to the extreme red, and the green ; but the absorbing power on
these two rays being nearly equal, the change of tint does not
take place. In an aqueous infusion of logwood, the type has,
in like manner, two maxima, detrésponditig to the red and
green; but the former is always predominant, and the only
change of colour it undergoes by a change of thickness, is from

a ruddy purple to a deep-red.

11. Among blue media we may in like manner distinguish,
such as absorb the spectrum with an energy regularly increas-
ing, from the more to the less refrangible extremity (whose
type in consequence is as in Fig. 8.), and those whose types
have other maxima, as in Fig. 2. Blue solutions of copper are
in the former case; and the best example, perhaps, is the beau-
tiful blue liquid produced by dissolving carbonate of copper in
carbonate of ammonia, or supersaturating any cupreous salt
with the ammoniacal carbonate. The extreme violet ray seems
capable of penetrating through almost any thickness of this
medium ; and this property, joined to the unalterable nature
of the solution, and the facility of its preparation, render it a
valuable resotirce in optical experiments ; and a tube of some
inches in length, closed at the ends with glass-plates, and filled
with this solution, is the instrument I always employ in expe-

riments

454 ON THE ABSORPTION OF LIGHT BY COLOURED MEDIA,

riments on the violet end of the spectrum. I have met with
no coloured glass possessing a similar character.

A solution of oxalate of nickel (free from cobalt) in ammo-
nia, may at first sight be mistaken for the ammonio-carbonate
of copper just mentioned. When set side by side with it,
however, it is characterised by the greater purity of its blue,
which amounts to an indigo tint, while the cupreous solution,
owing to the excess of the violet rays, has a strong blush of
violet. Examined with a prism, the solution of nickel is
found to absorb the most refrangible red, the yellow, green,
and extreme violet rays, with peculiar energy ; but, what is re-
markable, the extreme red rays are transmitted by it with fa-
cility, and with their usual definite character. Their illumi-
nating power is too feeble, however, to affect the tint of the
liquid, and in very great thicknesses they are absorbed, leaving
only an image on the confines of the blue and violet. The
type of this medium is as in Fig. 9.

12. The yellow rays are absorbed with peculiar energy by
most purple media, but by none more decidedly than by a so-
lution of archil. This liquid, in small thicknesses, is of a neu-
tral purple hue, but becomes more ruddy by an increase of
thickness, and soon passes to the deepest red. (See Fig. 10.)
On the other hand, the various shades of purple, which pass
on one side into rose-colour, peach-blossom, and crimson, and
on the other into plum-colour and violet, arise from a mini-
mum of the spectrum in the space occupied by the green rays.
The various shades of purple glasses, the acid and alkaline so-
lutions of cobalt, &c. afford examples of this minimum.

13. Hitherto I have supposed the illumination employed
to be that of solar light, or ordinary day-light, and the above
results

-AND ON THE COLOURS EXHIBITED BY.CERTAIN FLAMES. 455

results are of course, influenced by the peculiar. character of
this light, as those rays which the sun does not emit, or emits
but sparingly (as inthe confines of the red and yellow), can-
not be found in the transmitted beam, however well disposed
the medium may be togive them passage. These rays, how-
ever, may exist in light from other sources, as star-light, elec-
trical or phosphorescent light,.or that of flames, sich, differ
_extremely in their types when examined with the prism, and
that in aymanner the most capricious imaginable. | I shall here
set, down a few examples of remarkable flames nial Lhave
observed. |...

Sulphur, when burning ng its antl feeble flame, emits all
the rays, but principally the violet and blue. When the in-
flammation is violent, however (as when a piece of sulphur is
thrown into a white-hot crucible), the light emitted is perfect-
ly homogeneous, being a pure, brilliant yellow, and of a re-
frangibility so strictly definite, that all the minute flickerings
of its flame, seen through a prism of the largest refracting
angle, appear as, sharply defined, and free from nebulosity, as
when viewed with the naked eye. As the violence of the in-
flammation) abates; a faint train of green. and momentary red
spectra appears.

To insure a regular and violent inflammation of the sulphur,
I attempted to burn it with nitre, but the definite character of
the flame was, now lost, other colours coming in, and, in parti-
cular, two red spectra, sharply separated from the yellow and
each other, as in Fig. 11., in which the dotted curves repre-
sent the additional portions of the type arising from the nitre.
414, The flame of alcohol (a common spirit-lamp), consists
of two portions,—a cone of yellow flame, inclosed ina shell or

_envelope of blue, but projecting above it, like an acorn from

VOL. IX. P. Il. 3M. its:

456 ON THE ABSORFTION OF LIGHT BY COLOURED MEDIA,

its cup, or, rather, like a rose-bud from its enveloping calyx.
The yellow cone extends only about two-thirds of the way
down; and the bottom, or purely blue portion of the flame,
emits no yellow rays ; its type, when examined with the prism,
being as in Fig. 12., consisting of an ill-defined train of red, a
bright but undefined green, with masses of blue and violet
light varying in their character. The middle portion of the
flame, whose light emanates at once from the blue envelope
and the yellow cone, has the same type, with the addition of a
bright yellow spectrum, as marked by the dotted line in
Fig. 12., while the upper portion of the flame consists of light
{poste homogeneous, and corresponding to the less refran-
gible portion of the yellow, as denoted by the dotted line
alone. Its tint is visibly more inclining to orange than that
of the yellow in the solar beam, and it is extremely enfeebled
by the interposition of the glass described in Art. 8., which
transmits the latter so readily.

If the flame of a spirit-lamp be viewed through a glass con-
sisting of a pale-orange and.a pale-green one, cemented toge-
ther, the light transmitted is homogeneous, and if inclosed in
alanthorn of such combined glass, may be used as a mono-
chromatic lamp. .

15. The tinges given to the flame of alcohol by different’sa-
line combinations are well known, but have never been‘de-
scribed with any exactness, ala some of agin ee re-
markable peculiarities.

If muriate of strontia be tlie ‘salt held ‘in ‘Wdlntiol, the
flame assumes a beautiful carmine-red colour. When viewed
through‘a prism, with the usual precautions’ to diminish the
ghee breadth of the incident pencil, a broad, ‘but ‘well-

defined red, and a narrow yellow image, are perceived sépa-
rated

AND ON THE COLOURS EXHIBITED BY CERTAIN FLAMES. 457

rated from each other, by a very obscure, but not wholly black
space, almost equal in breadth to the red... This red, however,
consists entirely. of the more refrangible portion, and is extin-
guished |by.a standard glass, which transmits only the extreme
red rays. The yellow image is remarkable... Narrow as it is,
it, is evidently bifid, being divided by a black line into two
images, of tints very visibly different. The most refracted. is
a.pure pale yellow, without.any ruddy or green tinge... The
least is.a decided orange, equally contrasted with the yellow
on the one, side, and the red on'the other. What is yet more
remarkable is, that when this bifid image was viewed through
the bright-red. glass, described in Art. 3., it. was rendered
single, the: yellow being entirely. absorbed, while the orange
was very little, affected. At the. point of the flame, the yellow
image (which seems strictly homogeneous, and is quite sharp-
ly defined on both sides), terminates the spectrum ; but in the
lower -part a faint green. image is visible, and. some traces of
the blue and. violet, becoming stronger as we approach the
bottom. ». (See Fig. 13.) .
d ; dMuriate, of lime, dissolved in spirits gives no such orange
image. | _ The itype.of this flanie is asin Fi ig. 14.. Neither does
wpriate of, baryta.or corrosive sublimate, the type of whose
flomiess which are very similar, is represented i in Fig. 15.

' The solution of muriate of copper.in alcohol is of an emer-
ald-green. colour ; that of the nitrateis blue. The colours of
their. respective . flames are the reverse; the former giving a
bias, and the latter 2 a fine eer flame, the types of which are

1Roweie acid en nit ne remarked for its efficacy in com-
nynicaritia a green tinge to the flame of alcohol... Exaniined
withthe prism, t the spectrum. of this flame is seen divided into
six, a feeble red, a bright yellow, two greens of the same tint,

one

458 ON THE ABSORPTION OF LIGHT BY COLOURED MEDIA,

one extremely faint bluish-green, and one almost evanescent
violet ; its type being in consequence as in Fig. 18.

It is needless to insist on the advantage that may be taken
of these and similar properties of coloured flames and media,
in optical researches. The power they afford of insulating
rays of several species, of a refrangibility perfectly definite,
and capable of being identified at all times, offers every facili-
ty for a more exact examination than has hitherto been under-
taken, of the dispersive action of media on the intermediate
rays, as well as for the direct determination of the dispersions
of the extreme ones. A method which I have sometimes
practised with success for the latter purpose, is as follows : Let
two parallel slits AA, BB, the one half the length of the other,
and each about two-tenths of an inch in breadth, be made in
a screen, and being placed horizontally in a window, examin-
ed with a prism of known refracting angle, having its edge ho-
rizontal. The eye being defended by a thickness of blue glass
(such as is described in Articles 3. and 5.), sufficient to stop the
green, yellow, and most refrangible red ; two images a a, a’ a’,
and bb, bl’ b’, of each slit are seen a red and a violet of each;
the red being perfectly sharp and well defined ;’the violet also
pretty well defined at its most refracted edge. The eye and
prism being now gradually withdrawn, the violet image a’ of
the longer slit will approach the red 6 of the shorter one, and
at length be seen projected upon it, (the apparent angle be-
tween the slits diminishing, while the angle of dispersion re-
mains invariable). When arrived at such a point that (the
prism being placed in a position of minimum deviation) the
corresponding edges a’ a’ and 66 form one straight line, which
may be hit with very considerable exactness; it must be stop-
ped, and its distance from the slit measured. In this situa-
tion, the difference of deviation of the extreme rays, is equal

to

AND ON THE COLOURS EXHIBITED BY CERTAIN FLAMES. 459

to the angle subtended by the interval between the corres-
ponding edges AB of the slits; and this being known, the dis-
persive power is easily calculated. In fact, if i be the interval
between the corresponding edges of the slits observed, and d
their distance from the prism, A the angle of the prism, D the
deviation of the extreme red rays, » the refractive index for
those rays, and p the dispersive power, we have

pi 008 (FH)

p= a where 04 = 4% =
sin =>

For example, to determine the dispersions of 8 specimens of
glass, I found by this method as follows:

$4 = 0.535 —
, Number, &e. of Glass. | A= pi — d= ou — p=

ef ee ee

1, Flint, - 39° 40'126° 8 | 1.6010 | 34.40 | 0.03849 | 0.06404

2. Do. - 30 36418 36 | 1.5780 | 49.76 | 0.03705 | 0.06409

8. Do. - 25 5}15 103 | 1.5847 | 61.95 | 0.03734 | 0.06386
‘14. Do. “ Heavy,” - |24 0/14 56 | 1.6028 | 61.40} 0.03951 | 0.06555
45. Flint, . - 24.15) 14 38 | 1.5847 | 64.08] 0.03747 | 0.06409
6. Crown, = 40 6/23. 1 | 1.5265 | 58.60 | 0.02189 | 0.04063

7. Do.a different kind, | 24 40/13 293/ 1.5301 | 94.90 | 0.02494 | 0.04704

8. Plate, - 24 45}13 52} 1.5133 |102.30| 0.02616 | 0.05096

These results will doubtless appear extraordinary, after all
that has been written on the subject of dispersive powers.
The highest value of p, for flint-glass, given in Dr BrewsTeEr’s
' Table, is only 0.052, which is 4th lower than any of these re-
sults; yet I have no doubt of the correctness of my observa-
tions. The agreement of the dispersions of the three first spe-
cimens of flint, within a 260th part of their whole quantity,
while the refractive indices differ so considerably, is not a little
remarkable. The prisms used were made at once, by the same

artist,

460 ON THE ABSORPTION OF LIGHT BY COLOURED MEDIA, &c,

artist, for another purpose, and were probably taken from the
same melting pot. Meanwhile, it ought not to excite sur-
prise, that the dispersions deduced by this method should con-
siderably exceed all former estimates. It will be recollected,
that they are founded on observations of rays situated rigor-
ously at the extremities of the spectrum. These rays elude
all ordinary observation in the solar spectrum, and are too
feeble to exert any sensible influence on the colours of the
edges of objects, in the usual mode of compensation. This
latter, indeed, being merely comparative, assuming as known
the dispersion of a standard prism, its results must be affected
by all the uncertainties attending the determination of this ele-
ment, which, if obtained by actual measurement of the solar
spectrum, must, as I have before observed, necessarily err con-
siderably in defect: add to which, the method of compensa-
tion, owing to the “ irrationality of the coloured spaces,” can
only give results corresponding to the union of the two bright-
est and most strongly contrasted colours, which may differ
considerably from those corresponding to extreme rays. The
yalues of p for the crown and plate glass, Nos. 7. and 8., may
possibly be somewhat incorrect, from the smallness of the re-
fracting angles of the prisms used.—I have the honour to re-
main, dear Sir, with sincere regard, yours,

Joun FE. W. Herscuen.
Slough, July 24.1822.

XXXII.

PLATE Xxx.

Fey. Eng® for the Royal Soe: Tran Vol IX page 462.

Fig. 6. ||

|
Appearance near a |

- mail

! y
4 8
Sh 3
=

a &

Qualvig

= ws

XXXIL—On the Mineralogy of the Faroe Islands, By W. C.
_ Trevetyan, Esq. F. BR. S. E.

(Read Nov. 18. 1822. )

- My pean Sm, Wallington, July 22. 1822.

In compliance with your request, I send you a few notes of
some of the principal geological facts I observed in Faroe,
which may serve as a supplement to Sir Grorce Mackenziz’s
and Mr Attan’s accounts of these islands, which, as far as
they extend, I found perfectly correct. -

Tue Coal in Suderoe, which was not visited by them, is si-
tuated ‘ between two thick beds of hard clay, resembling the
Clunch-clay of this country ; to which succeed beds of trap. In
some parts, pieces of petrified wood are very abundant in the
superincumbent, clay, and also nodules of ironstone ; and in
the coal, pieces of wood resembling charcoal. The coal has the
same degree of inclination as the other beds, dipping towards
the south-east, at an angle of about 4° or 5°; being the same as
‘the dip i in the other islands, excepting in pat of ‘Myggenveas,
“where it ‘is much greater, being near 45. ‘The thickness of
_the coal varies from a few inches to 5 or 6 feet, and in quality
much

462 ON THE MINERALOGY OF THE FAROE ISLANDS.

much resembles the Scotch coal generally consumed in Edin-
burgh. It is but little worked, owing to the want of time, and
peat being abundant, and more easily obtained. Scarcely any
is taken to the other islands, as they have no vessels of suffi-
cient size for that purpose. A few cargoes were carried some
years since to Copenhagen, but not being found to answer, the
exportations were discontinued.

In the map of Suderoe, Plate X XIX, Vig. 8. copied from
Captain Born’s chart, the spots where coal has been observed
are marked with a double line, and where it is worked, with a
broad black line. The section below the map shews the situa-
tion of the coal from the level of the sea to the summit of a
hill south of Famoye, where it is stated to occur, though we
could not perceive it, which might perhaps be owing to the su-
perincumbent rubbish.

The coal on Myggenzas appears to be in the same position,
but not of sufficient thickness to be worked. On Tindholm
are also appearances of it and the clay, apparently enclosed in
the trap.

At Tiodnenzes, near Qualboe, a mass of columnar Basalt
is intruded into the place of the coal, which disappears near it,
as shewn in Fig, 1.

The best instance of columnar basalt which we saw, is near
Frodboe in Suderoe ; it is well described in Lanpt’s History
of Faroe.

The marks of fusion, mentioned by Sir GrorcE Macxenziz,
are very frequent, and also another appearance which may
perhaps be connected with it. The upper part of many of the
beds (more particularly of the amygdaloidal), is filled with
small insular perpendicular cavities, as if caused by the escape
of a gaseous fluid, when the rock was in a soft state. They are
sometimes empty, but frequently contain zeolite.

One

—

hbcrwis, Soo

~—_s

ON THE MINERALOGY OF THE FAROE ISLANDS. 463

One of the most remarkable beds we observed, is the Green
stone mentioned by Mr Atran (p. 255. vol. vii. Royal Society
Transactions), which does not conform with the general posi~
tion of the trap. The annexed sections, Figs. 2, 3, 4. will give
a better idea of its position than can be done in words.

Another bed of the same nature appears in Osteroe, near
Zellatrze, part of which is represented in the sketch Fig. 5.
Royafiall is a mountain above 2000 feet high, nearly equi-
distant from Ore and Zellatre. This bed, at the outcrop,, is
broken into columns; but, a few yards from it, the surface
seems quite compact.

Near Rideviig is a curious mass or vein of basalt, Fig. 6. re-
posing on an amygdaloidal rock, which gave me the idea of a
stream of lava. It may be traced for about 30 yards, when it is
concealed by rubbish and earth. Its breadth is three yards
and one-half, and thickness one yard.

Figure 7. represents a basalt lying on an amygdaloid, (the
shaded part), which also appears to be intersected by numer-
ous veins of the former, as if a number of fissures in it had
been filled up by the basalt flowing over it, when in a fused
state; or perhaps it is a conglomerate, or trap-tuff. I am sorry
I neglected examining it more particularly.

Near Leinum Lake we obtained specimens of noble, fire
and pearl Opal, in a bed of felspar-porphyry, through which
they are disseminated in small nodules. They were discover-
ed by Mr Hotm of Quivig since Sir Gzorce Mackenzir’s
visit.

Native Copper is very frequent, though not abundant. It oc-
curs generally in amygdaloidal rocks. In Suderoe, near Fama-
rasund, we found it in thin plates in a bed of claystone. Some
of it contains gold, also (but rarely) found separate.

VOL. IX. P. II. 3N I

464 ON THE MINERALOGY OF THE FAROE ISLANDS.

I may remark, that we found compact zeolite in a stalacti-
tic form, evidently of recent formation, and deposited from
water, in the same way as stalactites of lime.

We observed some hair zeolite, which, when pressed, gave
out a milky fluid.

Believe me, dear Sir, very truly yours,

W. C. TREVELYAN.

To Dr Brewster.

XXXII.

XX XIII.—Electro-Magnetic Experiments and Observations.
By Tuomas Stewart Traiz, M.D. F.R.S. Epin. &
Witiram Sconzssy, jun., Esq. F. R. S. Lonp. & Epiy.

(Read May 6. 1822. )

6 interesting discoveries of OrrsTED, and the subsequent
researches of AmprrE, Araco, Davy, and Von Bucu, which
promise to throw a clearer light on the mysterious nature of
Galvanism and Magnetism, induced us to undertake, and pur-
sue conjunctly, a series of Electro-magnetic experiments. In
prosecuting our inquiries in this new branch of scientific in-
vestigation, we have observed various interesting facts, some
of which appeared to us new, while others did not seem to have
been detailed so fully as their importance merited.

Some of our earliest experiments on this subject were per-
formed in November. 1821, with a cup of platina and slip
of rolled zinc, in the manner proposed by M. M. Von Bucn*.
In order to ascertain the effect produced on the needle, by
both sides of the lower portion of the zinc, the whole appara-
tus was placed on a piece of plate-glass. With this small ap-
paratus the electro-magnetic effect was slight, and its intensity
irregular, when the proportion of the acid amounted only to
sath or even 7, th of the liquid employed ; but the needle was

3N 2 é very

* Annals of Philosophy, vol. ii. p. 282.

466 ELECTRO-MAGNETIC EXPERIMENTS AND OBSERVATIONS.

very sensibly affected, whenever the strength of the acid li-
quor in the cup was sufficient to cause such an effervescence
with the zinc as to render the liquid turbid.

The most striking phenomena of this galvanic arrangement
are, the different effects produced on the magnetic needle by
the relative positions of the platina and zinc, in regard to the
magnetic meridian, and the opposite influence of the outer
and inner sides of the slip of zinc, as will be seen in the tabu-
lar results below.

1. Cup North.
1. Compass at O. See Pl. XXX. Fig. 1. deflected to the E *.

2. - I - - - W.
3. - i - - - W.
4. - 0 - - - E.

2. Cup South.

1. Compass at O, deflectedto W.
2. - I, - E.
3. - 1, - E.
4. - 0, - W.

3. Cup West.
1. Compass at O, not sensibly deflected.

Bs - I, _ inversion of Poles.
3: - i, inversion of Poles.
4. ~ o, not sensibly deflected.

4. Cup Kast.
1. Compass at O, inversion of Poles.

2. - I, not sensibly deflected.
3. - i, not sensibly deflected.
4. - 0, inversion of Poles.

Tn

* In this paper, where it is not otherwise specially indicated, the deflection, to
either hand, means the deflection of the North Pole of the needle.

ee a

PLATE XXX Eng? tor the Royal Soc. Tran VotI&page #66.

Fig. 2.

PS Trail delt 4 WHLizwrs sculp ®

ALAR

ete ah" ope

ach 4c 3 ft: My, Get Fee

7

ELECTRO-MAGNETIC EXPERIMENTS AND OBSERVATIONS. 467

In using this apparatus, we found it necessary to change the
acid frequentiy, otherwise the results were not so complete as
stated in the 3d and 4th series, and the action on the needle
appeared to be subject to capricious and sudden movements,
probably produced by the unequal action of the zine and acid.
We’ therefore constructed another apparatus, which combines
simplicity with cheapness.

It consists of two single plates of zine and copper, 4 inches
square, retained about 3th inch apart by a slip of mahogany
rivetted to them, as in Fig. 2. This, while it preserves the
due position of the plates, affords a convenient support to the
connecting wires or helices, which can be instantaneously
changed without displacing the plates; for the ends of the
wires are merely inserted into holes which perforate the wood.
When experiments were to be made, the plates, thus connec-
ted, were placed in a ‘shallow earthen-ware dish, containing
the acid liquor *.

Our first experiments with this apparatus were made on 15th
November, and have been many times since repeated with the
same results.

Experiments with the simple connecting-wire, Fig. 2.

1. Zinc North.

1. Needle placed below the wire, deflected to the W.
y sbaitegines above = = E.
2. Zinc:

* The liquid which we found most convenient, is 1 part of nitric acid with 30
parts of water, and $ a part of sulphuric acid. The zinc plates were made accord-
ing to Messrs Sirvesters’ and Rosson’s patent, now in the hands of Messrs Put-
tips, GEorce and Co., about 7; inch in thickness; the connecting wires and heli-
ces were of copper, or of brass wire, from ;1, to ;4 inch in thickness; the helices
most used had a diameter of about 2 inches; and the needle employed was either
a small pocket compass, with an agate cap, or a naked needle, supported on a fine.
point fixed at right angles on a glass rod.

468 ELECTRO-MAGNETIC EXPERIMENTS AND OBSERVATIONS.

2. Zinc South.
1. Needle placed below the wire, deflected to the E.
2. - above - = W.
3. Zinc West.
No sensible effect either above or below the wire.
4. Zinc East.
No sensible effect either above or below the wire.

In these experiments, there appears to be a maximum of
deflection when the connecting wire is in the magnetic meri-
dian ; but when it is at right angles to that meridian, the
effect is imperceptible. This, however, is evidently owing to
the small portion of the connecting medium, which, in this po-
sition, can act on the needle; for when a broad piece of metal
was substituted for the connecting wire, the needle was power-
fully acted on, as was evident by its short oscillations ; and the
same thing was observed with Von Bucu’s apparatus above
described.

In order to ascertain how far the influence of the connecting
wire depended on the supposed direction-of a galvanic current
or currents, passing from one metal to the other, a connecting
wire was bent several times at right angles, as is shewn in per-
spective in Fig. 3., and the following effects were observed on
applying a needle to different parts of the wire, in different po-
sitions of the plates.

1. Zine North.

When the needle was presented to those portions of the
wire in the magnetic meridian 1, 2, 3, the deflection was as
follows :

1. Above the wire, deflection - to W.
2. Below - - > to E.
but in other parts of the wire there was no deflection.

2. Zinc

ie

ELECTRO-MAGNETIC EXPERIMENTS AND OBSERVATIONS. 469

2. Zine South.
When the needle was presented to the portions of the
wire in the magnetic meridian 1, 2, 3.
J. Above the wire, deflection - to E.
2. Below - - to W.
but in other parts of the wire no sensible deflection.
3. Zinc West.
In this position there are two parts of the wire in the
magnetic meridian 4, 5, which present reversed results.
1. Above that portion, number 4, deflection to E.

2. Below - = 4, = to W.
but 3. Above - - 53 - to W.
4. Below - - 5; : to E.

4. Zine East.

In this position the influence of the portions 4 and 5 were
exactly as in the last position of the zinc. At first sight the
results of former experiments ought to have led us to expect a
difference ; but a little reflection will shew, that if these effects
are produced by a current passing from the zinc to the copper,
by the connecting wire, when the zinc is west, the current
must pass northward through 5, and southward through 4; and
in the opposite directions through both, when the zinc plate
is placed to the east of the copper. This circumstance coun-
teracts the effect of turning the plates, and the appearances
agree with the result of our previous experiments, no less than
with those that follow.

The phenomena of electro-magnetism appear to favour the
idea of currents capable of affecting the needle differently,
passing in opposite directions, and on opposite sides of the
connecting wire, from the two metals forming the galvanic ar-
rangement; and the results which we obtained with the bent
wire, prove that the influence of the relative position of the

zinc

470 ELECTRO-MAGNETIC EXPERIMENTS AND OBSERVATIONS,

zine and copper plates, depends rather on the direction which
is thus communicated to the electro-motive currents, than on
the point of the compass from which they begin to flow.

Helices were substituted for the connecting wires already
described. These were usually formed by bending copper-
wire 10 or 12 times round a wooden cylinder. We did not find
any difference in effect, whatever might be the metal of which
they were made, or whether they were 3, 1, 2, 3, or 4 inches
in diameter; but we found those of two inches most con-
venient in our experiments. They were either right or left
helices ; and for one experiment we employed a helix, one-
half of which was a right, and the other a left helix *.

In the following experiments, the needle was generally in-
troduced iu the centre of the helix ; but it did not alter the re-
sults, when moved about in it, provided the needle had free
space to turn round.

Experiments with a Right Helix. Fig. 5.

. Zine North.

Needle introduced in the axes had its poles inverted.
. Zine South.

No deflection of the needle.
3. Zinc West.

Needle deflected to the E.

4. Zinc Fast.
Needle deflected to the W.

—

bo

Experiments

* Those unaccustomed to such operations, find some difficulty in distinguish-%
ing between a right and a left helix; but if it be placed on one end, the spires of
a right helix rise in the direction of the sun’s diurnal course ; those of a left helix
in the opposite direction.

ELECTRO-MAGNETIC EXPERIMENTS AND OBSERVATIONS. 471

- Experiments with a Left Helix. Fig. 6.

1. Zine North.
Needle not deflected.
2. Zinc South.
Needle had _its poles inverted.
3. Zinc West.
Needle deflected to W.
4, Zinc Fast.
yy eedle deflected to E.

Experiments with a Double Helix.

This helix is 6 inches in length, and 2 in diameter; it con-
sists of 16 spires, 8 of which are in a right, and 8 in a left di-
rection.

The needle, when placed in either end, was deflected, as in
the order of the simple helices, to which it belonged. When
placed in the centre of this helix, the needle only obeyed ter-
restrial magnetism ; but the slightest deviation to either extre-
mity produced a deflection.

Instead of the helices, we employed a thin tube of brass,
Fig. 4.; but with the small apparatus no certain effects were
produced. In subsequent experiments, however, with a larger
galvanic arrangement, we remarked singular irregular motions
of the needle in its axis, which were not easily reducible to
any general law.

To increase the power of our electro-motive apparatus,
without rendering it complicated, seemed desirable, as we
thought that we perceived a law, respecting the action of he-
lices, which we hoped to develope more clearly by an increase
of power.

We procured a copper tray, 14 inches long by 10 inches
wide, and 1 deep, AA, Fig. 7. BB is a plate of zinc, 13

VOL. IX. P. II. 30 inches

472 ELECTRO-MAGNETIC EXPERIMENTS AND OBSERVATIONS.

inches long by 9 wide, which has a short pipe of the same me-
tal soldered to its centre, for supporting one end of the con-
necting wires, while the other is inserted in a similar pipe sol-
dered to the copper-tray, as represented at C. When this ap-
paratus was used, nothing more was necessary than to separate
the zinc and copper by a few slips of window-glass, or by thick
paper, and then pour the acid into the tray. The effect of
changing the relative positions of the metallic plates, as in the
former experiments, could be instantly produced, by moving
one end of the connecting wire to either side of the copper-
tray. On this account, it is the most convenient form of the
apparatus, and is sufficiently powerful to give sparks, and to
magnetise small sewing needles, if previously softened by
heat.

With this apparatus all our former experiments were repeat-
ed, and the following are the general results which were ob-
tained.

The effect of the simple and conducting bent wires differed
only in energy from what was before observed. The deflec-
tions, when the acid was fresh, was = 90° to either hand; and
in those positions where there was no deflection, there was
evidently very strong electro-magnetic action.

When helices were employed, we found that the needle in-
troduced invariably arranged itself parallel to the axis of the
helix, whatever might be its direction. This law was striking-
ly illustrated by the combination represented in Fig. 8. Here
a very long left helix was employed, portions of which were
bent toward the four cardinal points; and on successively in-
troducing the needle into each, it assumed the direction of the
axis of that portion of the helix; but in such a manner, that
the north pole of the needle is always directed, so as to meet

the

ELECTRO-MAGNETIC EXPERIMENTS AND OBSERVATIONS. 473

the supposed current, passing from the zinc toward the copper
by the helices.

With right helices, the needle as invariably arranges itself in
the direction of the axis of the helix; but, in this case, the
south pole of the needle is always directed, so as to meet the
current, which we have supposed to proceed from the zinc to
the copper by the connecting wires.

This general statement will supersede the necessity of de-
tailing the numerous experiments which we made to deter-
mine these laws. It is evident that the deflections of the
needle, when the helices were arranged either in an east or a
west direction, could never be less than 90° ; and in certain
directions must have amounted to complete inversion of the
poles.

The foregoing experiments were made with horizontal heli-
ces; and we conceived that it was important to ascertain the
effect which an inclined, or a vertical position of the helices
might produce on the needle.

With a vertical helix, as‘in Fig. 7., a needle, poised on a
centre, dipped so much as to have its free motion destroyed :
we therefore introduced a magnetic needle, suspended by a
fine thread, or a fibre of raw silk. This uniformly assumed
the direction of the axis of the helix, wane truly vertical, or
inclined to the horizon.

In a Right Vertical Helia.

1. When the end of the helix connected with the zinc is up-
permost, the N. pole is depressed.

2. When the end of the helix connected with the zinc is lower-
most, the N. pole is elevated.

That is, the south pole, as in a horizontal right helix, is
turned, to meet the supposed current proceeding from the
zinc.

302 In

474 ELECTRO MAGNETIC EXPERIMENTS AND OBSERVATIONS.

In a Left Vertical Helix.

1. When the end of the helix connected with the zinc is up-
permost, the N. pole of the needle is elevated.
2. When the end of the helix connected with the zinc is low-
ermost, the N. pole of the needle is depressed.
That is, the north pole, as in a left horizontal helix, is
turned, to meet the current proceeding from the zinc.

Similar experiments were made on helices inclined at angles
of 70° and 20°. The needles assumed the direction of tne axis
of those helices; and the other phenomena were similar to
what are above stated.

We may then reduce the influence of the interior of the he-
lices on electro-magnetic arrangements, into two general laws.

lst, When a magnetic needle is introduced into such a he-
lix, it has a tendency to assume a direction parallel to the axis
of the helix.

2d, When the helix is a right helix, the South pole of the
needle is deflected ‘toward that part.of it in connection with
the zine; and when it is a eft helix, the North pole of the
needle is deflected toward that part of it in immediate contact
with the zinc.

In prosecuting our experiments, we had occasion to observe,
that the upright wires supporting the helices, were not with-
out their influence on the needle. When the needle approach-
ed the vertical portion of the connecting wires, there were
marks of strong electro-magnetic action ; but the deflections of
the needle differed at each side of the wire. There is some.
difficulty in ascertaining the precise effects of each side of the
wire, and we therefore substituted, first, a rectangular tube of
copper, of the same form as the connecting wire in Fig. 2., the
sides of which were about “ths of an inch in breadth ; and after-
wards a solid piece of lead, cast of the same size and shape as

the

ELECTRO-MAGNETIC EXPERIMENTS AND OBSERVATIONS. 475

the tube. -With both of these, as a connecting piece, the de-

flections of the needle were found to be precisely similar.
These deflections will be easiest represented by references

to horizontal sections of the limbs of the connecting piece, as

below.

J. Zinc North.

w ) w
Copper. Zine.
Ss] se | n aie .
ée : e
1. Needle applied to s8, deflected 90° E.
2. g - nS, =.) 90° W.
3: - - wS, inversion of poles.
4. - - eS, no deflection, but vigorous action.
Be 2 = sN, deflection 90° W.
6. - - nN, - 90° b
7. - - WN, no deflection, but vigorous action.
8. : - eN, inversion of poles.
II. Zinc South.
w w
Zine. Copper.
J ke sly |?
ey e
1. Needle*applied’to “sS, deflected 90" W.
2. =~ nN Ss, ~ 90° E,
Bs 2 - wS, no deflection, but vigorous action.
4, J 5 eS, inversion of poles.
rt a - sN, deflected 90° E.
6. - - nN, - 90° W.
tts - - WN, inversion of poles. :
8. - - -eN, no deflection, but vigorous action.

Similar

476 ELECTRO-MAGNETIC EXPERIMENTS AND OBSERVATIONS.

Similar experiments were repeatedly made with the zinc
west and east ; but in both those cases, the effects of the ver-
tical portions of the limbs were perfectly similar to those here
given under II., or Zinc South ; so that the same table will re-
present the action of the four sides of the vertical limbs in
three positions of the zinc. When the compass is carried
round one of these vertical limbs of the connecting piece, the
needle makes one revolution on its centre.

We next examined the effect of the horizontal part of the
rectangular connecting piece on the magnetic needle.

J. Zine North.

1. Needle above the horizontal part deflected 90° E.
2. - below - - 90° W.

IJ. Zinc South.
1. Needle above the horizontal part deflected 90° W.
2. - below - - 90° E..
III. Zinc West.

1. Needle above shewed no deflection, but vigorous action.
2. - below had its poles inverted.

IV. Zinc East.
1. Needle above had its poles inverted.
2, - below shewed no deflection, but vigorous action.

When the needle was applied to the two perpendicular sur-
faces of the horizontal part, there was a difference of deflec-
tion, as it approached either the upper, or the lower surface,
partaking of the effect of that surface to which the compass
was approximated. The action of the upper and under sur-
faces of the rectangular conducting piece, when the zinc was
north or south, did not differ from that of the simple connec-
ting wire in Fig. 2.; but the breadth of these surfaces de-

veloped

oS lc

LECTRO-MAGNETIC EXPERIMENTS AND OBSERVATIONS. 477

veloped an effect on the needle when the zinc was west, or east,
which could not be detected by using a small connecting
wire.

On comparing the results obtained by using different kinds
of connecting pieces, it appears, that if the needle be applied
along their exterior surface, as in the oO
direction S, 0, N, the deflection will i
be the same, while the relative posi-
tion of the zinc and copper are un-
changed, or while the electro-motive
current flows in one direction ; and
if the needle be carried along the
interior surfaces of the connecting piece, as in the direc-
tion s, 7,7”, the deflection will be uniformly in the opposite di-
rection.

n

The thin brass cylinder Fig. 4. was then applied to the tray
and plate apparatus, Fig. 7.
I. Zine North.

1. Needle in its axis, deflected E.
2. - at its upper surface E.
3. - at its lower surface W.

II. Zinc South.

1. Needle in its axis, not at all deflected.
2. - above, deflected W.
3. - below - E.

III. Zinc West.

1. Needle in its axis not deflected, but vigorously acted on-
2. - above, not visibly acted on.
3. - below, had its poles inverted.

Zinc

478 ELECTRO-MAGNETIC EXPERIMENTS AND OBSERVATIONS,

IV. Zinc East.

1. Needle in its axis, deflected 90° E.
oH - above, deflected E.
a - below, not deflected, but strongly acted on.

The sides of this cylindric tube shewed no action, except
when the needle was moved toward the upper, or under part
of the tube, when it partook more or less of the action pecu-
liar to that surface.

The electro-magnetic effects of the outside of the cylindri-
cal tube, appear to differ in no respect from those of rectangu-
lar connecting pieces, or common connecting wires. When a
needle is introduced in its axis, and is deflected at all, that de-
flection partakes, more or less, of the direction it assumes,
when applied to the upper surface of either ; but the degree of
deflection appears to be subject to sudden variations and irre-
gularities, of which the cause was not always apparent. If we
may be allowed the expression, it seemed as if the electro-
magnetic current moved through the tube with difficulty.

Finding the outside of the tube giving such decided electro-
magnetic indications, we examined the action of the outside of
the helices.

Experiments with Right Helix.

I. Zine North.

1. Needle applied above, deflected 90° KE.
2. - below, - 90° WW.
Il. Zine South.

1. Needle applied above, deflected 90° W.
a - below, . 90. FE.

III. Zinc

ELECTRO-MAGNETIC EXPERIMENTS AND OBSERVATIONS. 479

III. Zinc West.

1. Needle applied above, deflected 90° W.
em = below, inversion of poles.

IV. Zinc East.
iM evils applied above, deflected 90° E.
2, - below, deflected to E.; but varying a
little in degree, as moved along the ee

Experiments with Left Helix.
I. Zinc North.
1. Needle applied above, deflected 90° KE.
2. - below, - 90° ~W.
II. Zinc South.
1... Needle applied above, deflected 90°
2. - below, - 90°
III. Zinc West.
1. Needle applied above, deflected 90° E.
Z. - below, inversion of poles.
IV. Zinc East.
1, Needle applied above, deflected 90° W.
vA 4 below, deflected to W.; but varying a
little in degree, when moved toward either end of the
helix.

These experiments shew, that the reversed action of right
and left helices is chiefly confined to their interior ; for when
the zinc is south or north, the outsides of left and right helices
act similarly on the needle; when, however, the zine is west
or east, the deflections of the needle are reversed in each sort
of helix. The analogy also between the outsides of helices,

VOL. IX. P. I. 3P and.

Hs

480 ELECTRO-MAGNETIC EXPERIMENTS AND OBSERVATIONS.

and the surfaces of the horizontal part of the rectangular
pieces is very close ; the upper surfaces of helices, when the
zinc is west or east, affording the only differences of action be-
tween helices and other connecting pieces, while a complete
inversion of poles takes place at the lower sides of ad/, when
the zinc is to the westward of the copper.

WE beg leave to lay before the Society these details of our
experiments, rather as contributions toward the materials of a
theory of electro-magnetic action, than with the idea of dedu-
cing from them any speculations on the nature of this mys-
terious agent ; yet we cannot avoid remarking, that, while the
substances connecting the poles of a galvanic arrangement be-
come real magnets, the opposite effects of their upper and un-
der surfaces appear to favour the doctrine of two electro-mag-
netic currents, moving in opposite directions ; and that the
Boreal Magnetism of the interior of Right Helices, and the
Austral Magnetism observed in Left Helices, combined with
the superior energy of helices over simple wires, seem to give
probability to the supposition, that the two currents have a
natural tendency to pursue a course in the direction of those
spirals.

XXXIV.

XXXIV.— Conjectures on the Analogy observed in the Forma-
tion of some of the Tenses of the Greek Verb. By Joun
Hunter, LL. D. Professor of Humanity in the Univer-

sity of St Andrew’s. Communicated by the Rev. Dr Lzz,
PAR. Se:

(Read Jan. 20. 1823.)

Tue following conjectures concerning the Analogy obser-
ved in the formation of some of the Tenses of the Greek Verb
seem worthy of farther inquiry ; for, if well founded, they
may be useful towards establishing juster rules for the forma-
tion of the Tenses in some instances ; and, particularly, they
will account for certain forms of the Verb in Homer and He-
stop, which, being apparent violations of the usual analogy,
have perplexed the grammarians, and reduced them to the
necessity of assuming imaginary new Presents, without autho-
rity, and for no other reason, but to account for such anoma-
lous forms.

1. The Perfect Middle has not a middle signification ; see
Kuster de Voce Media, 'sect.1. Its form, too, is active; and
therefore it probably belongs to the Active Voice, which, on
this supposition, becomes more regular and uniform, having

3P2 a

482 ON THE ANALOGY IN THE FORMATION OF SOME

a double Preterite, as well as a double Future and Aorist.
Thus,

. } ropa erura rerupa 1. Pret.
TUrTH
TUT eTrumoy rerura 2. Pret.

It is no objection to this account, that the second Preterite
may sometimes be found in a middle signification ; for active
verbs in all languages are sometimes used as middle, the reci-
procal pronoun being conceived, though not expressed. Thus
vera Bors in Greek, accingo in Latin, prepare in English :
omnes accingunt operi,—they all prepare (themselves) for the
work.

2. o in the second Preterite, or Preterite middle, uniformly
arises from ¢ in the Present, and from nothing else.

Aeyw, Achoya—BAerw, BeProre-

era, Acroima—rebw, weroiba

That Qdegw, jzigo, ayeew, and other such verbs having a li-
quid before w, make cQdoga, pmewogu, ryoge, and not pemoieus
2@borea, ayo, &c. is no exception from the rule. For all
such verbs probably had of old not «, but < only, in the pe-
nult. Thus Jago seems to have been of old espa, whence
the old or Holic Future @egca. So pagw was weppw, whence
uwseos pars; and the old or olic form ayeppw is still to be
found. In like manner, 6<Gorx% seems, as Dr Moor has ob-
served, to be formed, not from Bara», but from the old verb
BcAarw, whence Beros jaculum.

3. Although the Ist Preterite, or Perfect active, generally
follows the analogy of the 1st Future, yet it sometimes, too,
observes that of the 2d. Thus,

Rredaw

OF THE TENSES OF THE GREEK VERB. 483

not éorzaxa from orsaw 1. Fut.

Srerrw makes } ; 7
but ieraaze from craao 2. Fut.

In the same manner, sewa, xe, ERA, OTEILU, &e. &e.

4. On the other hand, although the 2d Preterite, or Perfect
middle, generally follows the analogy of the 2d Future, yet it
sometimes, too, observes that of the lst. Thus,

not éocqjax from craaa 2. Fut.

Srexaw makes }
but écroaa from oreaw 1. Fut.

In the same manner, sea, area, nega, oreigw, &C.

Nay, from « in the penult, there often arises o in the Ist
Preterite, or Perfect active. Thus, rerouoa, Acroya, xexAcQu,
dedoaa, from repro, Aeyo, xrerra, Jed, Ke. And this seems
of old to have been still more frequent, and to have extended
also to the Passive voice. Thus, pcuogbas, rerogdas, in the old
or Aolic dialect from peppw (i.e. peiew) and seeder

5. In the same manner, although the Ist Aorist generally
follows the analogy of the 1st Future, yet it also seems, parti-
cularly in the more early periods of the language, to have
sometimes followed that of the 2d Future. Thus, yew, eyen—
SO ésree, queyxn OF nvema, wAcvawevos, sence, &e.

Since, then, there are in the Greek Verb two Futures, and
two Preterites, each of which Preterites follows the analogy ot
either Future; and, since there are two Aorists, and that the
1st Aorist also follows the analogy of either Future,—query,—
Would it not, from these facts, be rather probable than other-
wise, that the 2d Aorist should also follow the analogy of
either Future ; that, as from svza there is formed érvzo, so
from rv» there should be formed érudov? and, if this were

admitted,

484 ON THE ANALOGY IN THE FORMATION OF SOME

admitted, would it not account for such words as zaraGxceo,
Eduoero, Aske0, Oeaeo, ose, o1veTw, wee—zo, KC, which have so
much perplexed the celebrated Dr Criarxe, (see Notes on
Iliad, B. 35. E. 109.; I. 613.) in a manner more satisfactory
than is done by the arbitrary method of imagining new
Presents in —c», from which these forms may be deduced :
For it is only to account for such anomalous forms that these
new Presents have been imagined ; and the grammarians would
no doubt have assumed imaginary new Presents also, to ac-
count for such 1st Aorists, as yew, ¢xqa, if, by so doing, these
aorists could have been reduced to the usual analogy.

Now this supposition, namely, that the 2d Aorist, as well as
the 1st, follows the analogy of either Future, which is thus ren-
dered in some degree probable, has actually taken place, at
least in some instances. Thus the compounds of zum,

the 2d Aor. Part. axorewav, as well

from the Ist Future azoreua has in
Comore ved
as from the 2d Fut. TOT pts TOT Cea»

So igo, they came, I/. 23. v. 38.3 xareBnoero, Il. 24. v. 191.,
both of which follow the analogy of the first Futures, viz. ia
(from izw vento) and zara8ycouc And every person acquaint-
ed with the elements of Greek is aware, that, as ew is the
primary form, whence, by the common reduplication, arises,
first, zswevw, and then, dropping the short «, by what the
grammarians call syncope, wizvw, and as yew is the primary
form, from whence, in like manner, is derived yyw (Latin
gigno) and yiyvoyas: SO xeqw is the primary form, which, by
like reduplication and syncope, gave birth to sre, cado,
from which primary form era, making in the first Future
xeca, there is formed the second Aor. ézecoy in common use ;
which, in so far, both illustrates and confirms the foregoing
hypothesis.

The

OF THE TENSES OF THE GREEK VERB. 485

Tue foregoing paper was written about thirty years ago, be-
fore either Vituorson’s or Heyne’s editions of the Iliad were
published. It may not be improper, however, to subjoin some
facts contained in these two celebrated, editions, together with
a few observations, suggested by these facts, and tending to
confirm the opinion which I had been previously led to form,
of those anomalous flexions of the Greek Verb.

From the ancient Scholia, quoted by Herne’ in his obser-
vations on the various readings of the Iliad, and from the large
volume of Scholia published by Vitzorson, (as well as from
those contained in Barnes’s edition of the Poems of Homer,
published in 1711), it seems to be clearly established, that, in
the days of the Proremys, this form of the 2d Aorist, follow-
ing the analogy of the 1st Future, was more frequent in the
writings of Homer, than that of the Ist Aorist, formed upon
the analogy of the same Future; and that. it was the reading
received and approved by the most eminent of the Alexan-
drian grammarians, by Zenonvortus, the keeper of the Alexan-
drian Library, and by Aristarcuus himself.

While, however, the Greek scholiasts have recorded these
as the ancient and genuine forms used by Homer, they have,
I suspect, greatly erred in their manner of accounting for
them. After the lapse of so many centuries, these Homeric
forms had, in a great measure, become obsolete *, and the
other form, that of the 1st Aorist, had come into general use ;
and those grammarians could devise no other method of ac-

counting

* One instance, however, of this ancient Homeric 2d Aorist occurs in Tuxo-
critus, and another in CaLLimacnus; and, perhaps, by an attentive observer,
more might be found.

486 ON THE ANALOGY IN THE FORMATION OF SOME

counting for these old and now obsolete forms, but by imagin-
ing new Presents in —cw, of which they supposed these forms
to be the regular Imperfects. This manner of solving the dif-
ficulty has been implicitly followed by Eusraruius, in his
Greek Commentary on the Poems of Homer, and (I am sorry
to be obliged to add) by my late invaluable friend Lord Mon-
Boppo ; of whom, and of the dies Attici, now long gone by, in
which I enjoyed his learned and elegant society, I never can
think but with an indescribable feeling of satisfaction and re-
gret.

If, however, we acquiesce in this solution of the difficulty,
we must be content to abate somewhat of our admiration of
the Greek language, which has been heretofore held to ex-
press, with the utmost clearness and precision, all the various
and diversified conceptions of the human mind, even to their
minutest shades of difference. Indeed, that the Greeks, or
any enlightened people, should employ those forms of their
Verbs as Presents, which were familiar to every ear as appro-
priate expressions of the Future, or, as Eusrarurus often ex-
presses it, should draw back the Future to express the Present,
is, when duly considered, a supposition in itself so unreason-
able, not to say absurd, that it would require better and more
conclusive evidence to support it, than has yet been produced.
Besides, where was the necessity of such an innovation ? what
advantage was to be gained by it? The original Presents re-
mained in common use. Why then employ the Futures, ducowes
and iZoue, E. G. as Presents, when dvw and dvoues, and iza
and izewc:, present forms in common use, would answer the
same purpose ?

There is still another consideration, to which due weight
ought to be given. There is no evidence whatever, that those

Present-

OF THE TENSES OF THE GREEK VERB. 487

Present-Futures, or future-Presents, in —ow and —covoi, ever
existed. They are not to be found in the Poems of Homer
or Hzstop. They are not to be found in the Greek authors
posterior to Homer and Hesiop; and of Greek authors prior
to the age of Homer and Hestop we know absolutely no-
thing. ete
From these considerations it seems to be evident, that the
existence of these Future-Presents is merely a gratuitous as-
sumption of grammarians, to account for the Homeric forms
Bacero, ducero, &c. which they could in no other way reduce
to any known analogy of formation.

This, however, the learned Dr Cuarxe had too much acute-
ness and good sense to admit ; and, accordingly, we find him
regarding these Presents as altogether fictitious. His words on
the passage ‘Q¢ agu Qurnoas, ameBnouro Iliad, II. 35. are
these: “ Editi plurimi habent azeGycero, a verbo ficto &roPnco-
“was.” And, to obviate the difficulty, he changes daeBycero

here into aw¢Grea70; and, when Bycero, or any of its com-
pounds, occurs, his general practice is to substitute the form
of the Ist Aorist, Bycu7o. But, even if it would remove the
difficulty, this change is unauthorised. The other form in
—:ro is attested as genuine by the Alexandrian grammarians,
is supported by the Greek scholiasts, by the ancient MSS. of
the highest authority, and by the early editions. In Vixzor-
son’s edition of the Iliad, which bears to be an exact tran-
script of a MS. of the tenth century, in the Library of St
Mark at Venice, the form is uniformly —ero, except in a
single instance, and in that one instance, I suspect —wro to be
an error of the press.

Dr Cuiarxe, however, soon finds that this change of —ero
into —ero, violent and unauthorised as it is, will not remove

VOL. IX. P. II. 3Q the

488 ON THE ANALOGY IN THE FORMATION OF SOME

the difficulty. In the address of Diomepr to SruEnetus, he
meets with the Imperative, zaraBaceo,

"Ovco, rerov, Kawcvgsacdy, zaraBqoeo dudes. Iliad. v. 109.

which he attempts to account for in this manner: “ Videtur
“ mihi Jmperativus ex futuro deductus, licet id non agnoscant
“ Grammatici; errareque eos, qui verbum hic in presenti fin-
gunt zaraByoouas Quanquam, analogia haud dissimili, per-
seepe usurpare visus est Homerus verbum dvcopou, dureo,
educero,”’ &c. Nothing can show more strongly the difficul-
ty which Dr Crarxe must have felt in accounting for these
forms, than that he is here obliged to have recourse to another
gratuitous assumption of an Imperative of the Future, a thing
unheard of before ; and almost to admit dvcowar as a Present,
from which to deduce édvcero as an imperfect. The fact is,
that he found the authorities in favour of ducero and éducero,
to be so numerous, and of such weight, that he did not ven-
ture, in these examples, to change —<ro into —aro.
Afterwards, however, he found himself obliged to abandon
this hypothesis of an Imperative of the Future, as well as his
original position, that these new Presents in —cw and —zowas
are imaginary ; and he appears at last (he or his son, it is un-
certain which) to adopt, in its full extent, the explanation gi-
ven by Eustarnivs. That commentator, whose remarks
would have been invaluable, had his taste and judgment been
equal to his means of information, if I rightly understand him,
has this observation on v. 154. of the 20th Book of the Odys-
sey: “ ’Oscere is sanctioned by a poetic rule of formation
“ (soinrinws nowonCeras) as the imperfect of the verb ow, the
* Future having retrograded into a Present. For of ow the
“ Imperfect is dor, the 3d person az, the Imperative the
same in sound, also owe, of which the plural is oere.”’

Dr

“

ce

“ce

oe

OF THE TENSES OF THE GREEK VERB. 489

as Cxarxe or his son adds in continuation: “ Atque analogia

“ quidem haud dissimili saepe usurpare videtur poeta ak
“ Quoopos, Bnoomas, Bnoero, &c. Vide autem ad JI. «. 109.’
(where, however, he reprobates the hypothesis of these new
Presents in —oowas) ‘ Occurrit eadem’ vox (viz. éiere) Jl.

‘ ». 103. 6. 718. et apud Turocritum, Idyll. xx1v. 48. Porro
“ fuerunt, teste Barnesio, qui dare ubique legendum statue-
“‘ yunt, sed nullo profectu. Nam, uti ipse annotat, occurrit
“ apud Homzrum oe in Imperativo, numero singulari, ubi isti
“ emendationi locus nullus est, &c. et apud Catrimacuum,
es dege sayuv, ose Vegsomove Hymn. in Cer. v. 1377.”

All the attempts, however, to account for these forms in
particular Verbs are partial and ‘unsatisfactory. _ As the facts
to be accounted for are all similar, the true solution must be
general, and such as will embrace them all. . Whether the me-
thod which I have ventured to suggest be of this description,
does not belong to me to determine. It possesses at least this
indispensable requisite, that it accounts for all the phenomena
in question.

It would be tedious and tiresome to enter on a particular
examination of every individual verb of the kind which we are
considering. It may not be improper, however, to select one
example for the purpose of illustration.

There are not many yerbs of more frequent occurrence in
Homer than izw venio in one or other of its parts. It is
found in the present :

Evbev (e Cypro) 3 vu» devgo 70d” IK xypore TOOK Ve
Od. ¢. 444.
and the Future jZoj~es occurs once in. Hxsiop, and ten or
twelve times in Homer; and, in not one of these instances,
can it by any sophistry be tortured into a present, or forced
3Q2 into

490 ON THE ANALOGY IN THE FORMATION OF SOME

into an expression of present time, in the sense in which pre-
senttime is generally understood. I shall note the places of
occurrence, that any person may, if he chuses, examine them,
and judge for himself. They are these: Hesiod. Op. et Dies,
vw 477.3 I. a 240.5 % 363, 502.; a. 18253 0. 505.3 Y. 47.;
w. 728. Od. d. 515.3 6.198. 3 2 276.

‘IZoueu, the Future of izw, then, must be decidedly excluded
from the catalogue of new Presnts, devised by the Greek Scho-
liasts to account for the supposed Imperfects, so frequent in
Homer. And yet anew Present izw, is equally necessary in
this, as in any other verb of the kind, to account for igo, they
came, the past tense, formed upon the analogy of the first Fu-
ture; which, though not noticed either by Dr Crarxs, or by
Heyner’, is no less frequent in Homer than the Future itself.
Thus,

AM’ ore On Teoirny IRON, rorapw re peorre, Il. ¢. 773.
At quando jam Trojam VENERUNT, fluviosque labentes.

See also, Il. x. 470. ; £433.39. 1.3 « 69% Od. y. 5,31, 495:;
d. 1.3 « 194. Hymn. in Apott. 411. 438. 230. 278.

Nor is there a single unequivocal example of the 1st Aorist
of this verb to be found in the poems either of Homer or of
Hesrop, except one, viz. iZa¢, which occurs in the Hymn to
APpo._o, v. 223. In that same Hymn, however, there are no
fewer than four examples of the form in -o» (éZov), and ano-
ther still in the Hymn to Mercury, v. 398.

This instance of Zo, so frequent in Homer, may therefore
be fairly admitted to be, in the language of the celebrated Ba-
con, an instantia crucis, clearly pointing out the true method
of accounting for all the other Homeric Forms of the same de-
scription. If so, there will be no longer any necessity for the

gratuitous

OF THE TENSES OF THE GREEK VERB. 491

gratuitous assumption of new Presents in -cw and -cowes,
to account for these forms, nor for supposing, with Dr Crarxe,
that xauruycco is an imperative of the Future; nor for chan-
ging, as he has generally done, the 2d Aorists Gycero, xura-
GBacero, &c. into regular first Aorists in —aro. We ought ra-
ther to restore the Homeric 2d Aorists in -ero, recognised as
the genuine readings by the Grammarians of Alexandria, and
the Greek Scholiasts, and confirmed by the ancient MSS. of
highest authority, and the early editions.

If the view which I have ventured'to give of these Home-
ric Forms in -ezo be well founded, it will hardly be neces-
sary to notice the canon of criticism attempted to be establish-
en by the learned Herne’, in his voluminous edition of the
Iliad, as to -ero and —azo, and the reasons for preferring
the one to the other in particular passages. See his 4th
vol. p. 506. Of the futility of that attempt, every classical
scholar, who will read with sufficient attention the last seventeen

- verses of the 3d book of the Odyssey, will be fully convinced.
The learned German has adopted, without scruple or hesita-
tion, the explanation of these Homeric Forms given by the
Greek scholiasts ; and, in allusion, 1 presume, to the difficulty
felt by Dr Crarxe, in admitting the existence of new Presents
in -c» and -cove, he states his opinion, and the grounds
of it, with decisive confidence, in the following words: “ Esse:
“ autem talem formam presentis Baooycs dubitari nequit ; nam
“ est v.c. ©.105. AA ay Euav oyewy éxiBqcEO,”’ p- 506. v. 4.
And on B. v. 35. he makes the following remark, not quite
consistent with itself: “ Quid hoc loco intersit, non video a
“ nisi quod ameGycero antiquioris vocis speciem habet : nova Sfor-
“ ma subnata, ut ducowas, edvooumy, et alia.” How the nova
forma should have antiquioris vocis speciem, I do not clearly
comprehend. But a gleam of truth will sometimes burst
through the darkness of inveterate prejudice.

42> on pub kina te wi ih

om fm ition te nora bitters % :

«ghia is Geaktivel lgnipogepn ion, toh wend geod s YOR IMODIE 03 «
_ennnrtooedt ies porated oi tnocat: iin re es fe
. Sodkepaninlaread penton. Bahay m pontibree lnvieog end oct ‘of Sig ae
J tit adgho MO .orak BP SNOAL et filoyen Bie 2 oe
» Si basisigboor 1 nls ch atthe <b iSieomroH ods #103291 rp a 7"
nO onl el diginibasle bh i

‘ni Ge Meunbions sfipret rey tenth ise dos
ts to stout. for Uacrolgifvoerehais te: Kean: ysiroitaag deo ie,
CLainwoH stgds Set svigpen eeemnet Pteiider wolrdi YE (a
th eonode> ack, tsa iw si Dobast liver: od dm Git; ‘emilee nt

ptengeetit Sear ra pa rc ta esa * a 3

|| gpimshsaqorcticenotasy edt ibail ne) aasiat neste # nea
hte vids eo@ > coyseeng telugitag “ai s99%0 oar avai: ot ae
ieee Tavs dqmaie todd Vo qiliad odd 10. BPZoq, fov= ah a

ovat Yel J ob ptratah siege ality Ihiw bdw 3 finials, €;

at hie data rials

seg ae 2 >

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vagina 2 PDA, ae
oe Sageat tyra ogre er

ye eh eee

SEP 0H, AIA MOT eons an &

pepe oma on vet f
gE BOO, rina pean Dee bop kia ”
oof Papas, 08 eat Le, ayy men: canrys «: seadue San 2

dened samisainos iliw dunt “to. solg @ itl * -Leadgiqnids —)

‘ Bh ouanasoviai ‘to eaortdish oat. = "

t oae

HISTORY OF THE SOCIETY.

*

yra1908 AHL TO YHOTaIE:

LAWS

OF THE

ROYAL SOCIETY OF EDINBURGH,

ENACTED 23D May 1811, 26TH FEBRUARY 1820,

AND 2475 January 1823.

I.

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Il.

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VOL. IX. P. IL. 3R IV.

496 LAWS OF THE ROYAL SOCIETY

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but no Ordinary Members shall be chosen in future under the title

and

OF EDINBURGH. : 497

and with the privileges of Non-resident Members. The Members at
present called Non-resident shall have an option of becoming Ordinary
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DS

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Xi.

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3R2 and

ee

* «A,B. a gentleman well skilled in several branches of Science (or Polite Litera-
ture, as the case may be) being to my knowledge desirous of becoming a Member of
the Royal Society of Edinburgh, I hereby recommend him as deserving of that honour,
and as likely to prove an useful and valuable Member.

498 LAWS OF THE ROYAL SOCIETY

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a President ; Four Vice-Presidents, two of whom shall be resident ;

a

ee

——, = ee

OF EDINBURGH. 499

a President for each Class of the Society; Six Counsellors for each
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XVIII.

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XIX,

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necessary discharge of his intromissions,

The

500 LAWS OF THE ROYAL SOCIETY

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XXXVI.

OF EDINBURGH. 501

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for the inspection of the Members.

XXVII.

_All articles of the above description shall be open to the inspection of
the Members, at the Hall of the Society, at such times, and under such
regulations, as the Council from time to time shall appoint.

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( 503)

LIST

Of the Orricr-BearErs and Mempers elected since the
26th January 1818.

November 30. 1818.
OFFICE-BEARERS.
Sir James Hatt, Baronet, President.

Right Honourable Lord Gray, Vice-President
Honourable Lord Guenuzx, } Ss rae cn

Professor Prayrair, General Secretary.
James Bonar, Esq. Treasurer.
Tuomas Auian, Esq. Keeper of the Museum and Library.

PHYSICAL CLASS.

Sir Grorcr §. Mackenzie, Baronet, President.
Dr Hope, Secretary.

Counsellors.
Lieutenant-Colonel Imrie. James Jarprng, Esq.
Professor JAMESON. Hon. Captain Napier, R. N.
Dr Brewster. Dr A. Duncan jun.

VOL, IX. P, I. 3s Literary

504

LIST OF OFFICE-BEARERS AND MEMBERS

LITERARY CLASS.
Henry Mackenzie, Esq. President.
Tuomas Tuomson, Esq. Secretary.

Counsellors.
Professor Dunbar. Lord Reston.
Rev. Mr Atison. Rev. Joun Tuomson.
Rev. Dr Jamreson. Rev. Dr Bruntow.

January 25. 1819.
MEMBERS ELECTED.

Honorary.
The Chevalier JosepH Hammer.

Orprnary.
Right Hon, Lord Joun Campse tt.
Sir Joun Hay, Baronet.
Dr SHooLBRED.
Parrick Fraser Tytier, Esq.
Colonel Davin Stewart of Garth.
Patrick Murray, Esq. of Simprim.
Dr James Murtieszury, Bath.
Dr Tuomas Stewart Trait, Liverpool.
Dr ALexanper Kennepy, Edinburgh.
Mr Auexanver Ante, Optician, Edinburgh.
Dr Witt1am Courter, Glasgow.
Dr Joun HEnNeEN.

Dr Joun VEITCH.
ANDREW

_ ELECTED SINCE 1818. 505

AnprEw Wanner, Esq.

Grorce Ranken, Esq.

Dr Marsuatx Hatt.

Joun Bortuwicx, Esq. Advocate.
Ricwarp Puituirs, Esq.

Wituiam Scoressy, Esq. jun.
Georce Forzes, Esq."

November 29. 1819.
OFFICE-BEARERS.
Sir James Hatt, Baronet, President.

Right Honourable Lord Gray,

Vice-Presidents.
Honourable Lord Gien.ex, i
Dr Brewster, General Secretary.

James Bonar, Esq. Treasurer.

Tuomas Axxan, Esq. Curator of the Museum and Library.

PHYSICAL CLASS.
Sir .G. 8. Mackenzie, Baronet, President.
ALEXANDER Irvine, Esq. Secretary.
Counsellors from the Physical Class.
James Jarpine, Esq. Giuzert Laine Meason, Esq.
Hon. Captain Napier, R. N. Professor Russert.
Dr A. Duncan, jun. Dr Hop.

LITERARY CLASS.
Henry Mackenzir, Esq. President.
Tuomas Tuomson, Esq. Secretary.

382 Counsellors

506 LIST OF OFFICE-BEARERS AND MEMBERS

Counsellors from the Literary Class.
Reverend Dr Jamieson. Sir Joun Hay, Baronet,
Reverend Joun Tuomson. Professor Curistison.
Reverend Dr Brunton. Hon. Baron Cierx Rattray.

January 24. 1820.
MEMBERS ELECTED.
Honorary.

His Royal Highness Prince Leoroxp.

His Imperial Highness the Archduke Joun.

His Royal Highness the Archduke Maximiay.

M. le Chevalier Detampreg, Perpetual Secretary of the
Academy of Sciences.

Orpinary.

JamesHunter, Esq. of Thurston.

Right Honourable Davin Boyz, Lord Justice-Clerk.

James Kern, Esq.

Right Honourable Sir Samus. Suepuerp, Bart. Lord Chief-
Baron.

James Narrne, Esq.

Joun CoLqunoun, Esq.

Henry Rarsurn, Esq.

Lieutenant-Colonel M. Stewart.

Cuarxes Bazsace, Esq. F. R. S.

Tuomas Guturie Wricut, Esq.
Joun

ELECTED SINCE 1818. 507

Joun F. W. Herscuet, Esq. F. B.S.

Apam Anperson, Esq. A. M. Perth.

Joun Suank More, Esq. Advocate.

Wituram Hatt, Esq. A. M.

Dr Grorce Aucustus Bortuwicx, Edinburgh.

Rosert. Dunpas, Esq. of Arniston.

Dr Samvuret Hiszerr.

James Rosson Scott, Esq.

Dr Rozert Haxpane, Professor of Mathematics, St An-

drew’s.

May 1. 1820.
MEMBERS ELECTED.
Honorary Memsers.

Count IrTERBuRG.

Orprnary MEMBERS.
Sir Joun Meave, M. D.
Tuomas Krynear, Esq. Banker.
Dr Witt1am Macponatp of Ballashore.

June 1. 1820.
MEMBERS ELECTED.
Honorary Mempers..
Count BerTHOLLET.

ForrIcn

508 LIST OF OFFICE-BEARERS AND MEMBERS

Foreign Memsers.

M. VavaveELin. M. Porsson.

M. Le Chevalier Lrcenpre. M. Prony.

M. Brocuant. M. Gauss.
Baron Vow Buca. M. Brumensacu.
M. Berze.ius. Count Vorra.
Baron KrusENsTERN. M. Kavsster.
M. Sismonp1. M. Deceranpo.

Orpinary Mempers.

Joun Hay, Esq. younger of Hayston. -
Captain Roserr Hay, R. N.
Dr BaLuinealt.

November 27. 1820.
_ OFFICE-BEARERS.
Sir Wauter Scort, Baronet, President.
Right Honourable Lord CRA WidouBachidgh ts,
Honourable Lord GLEn.ez,
Dr Brewster, General Secretary.
James Bonar, Esq. Treasurer.
James SKENE, Esq. Curator of the Museum and Library.
PHYSICAL CLASS.
Sir Grorce Mackenzie, Baronet, President.

ALEXANDER Irvine, Esq. Secretary.

Counsellors

ELECTED SINCE 1818. 509

Counsellors from the Physical Class.

Dr A. Duncan junior. Dr Horr.
Gitpert Lainc Meason, Esq.. Professor Wauace.
Professor RussEL1. Henry Jarprng, Esq.

LITERARY CLASS.

Henry Mackenziz, Esq. President.
Sir Witt1am Hamitton, Baronet, Secretary.

Counsellors from the Literary Class.

Reverend Dr Brunton. Hon. Baron Crerx Rarrray.
Rev. Dr Davin Ritcuiz. Right Hon. Lord Curer Baron.
Sir Joun Hay, Baronet. Reverend Mr Attson.

Ar this meeting the following resolution, moved by Dr
Hopreg, and seconded by Sir Grorce Macxenzir, Baronet, was

unanimously adopted, and ordered to be transmitted to Sir
James Hatt, Baronet.

“The Royal Society having, in compliance with the wish
of Sir James Hatt, Baronet, refrained from again placing
him at their head, beg to avail themselves of this opportu-
nity to offer him their best thanks, both for his long and
zealous services as their President, and for the numerous va-
luable communications with which he has enriched their Trans-
actions, and contributed materially to maintain the reputation
of the Society.”

January

510 LIST OF OFFICE-BEARERS AND MEMBERS

January 8. 1821.
MEMBERS ELECTED.
ALEXANDER Oswatp, Esq.
James WevpERBURN, Esq. his Majesty’s Solicitor-General.
Lieutenant-Colonel Srraton, C. B., &c. &c.
Dr Grana, Professor of Botany.

F ebruary 5.
MEMBERS ELECTED.
Foreign Memser.:
Sir Henry Bernstern.

Orpinary Mempers.
A. N. Macteop, Esq. of Harris.
Sir James M. Rippet1, Baronet.
ArcuiBaLp Betz, Esq. Advocate.
Jonn Crerx Maxwett, Esq.

March 5. 1821.
MEMBERS ELECTED.
Foreign Memper.
J. C. Orrstep, Secretary to the Royal Society of Copenhagen.

Orprnary Mempers.
The Right Honourable the Earl of Horeroun, GG. B,
Joun H. Wisnart, Esq. President of the Royal College of

Surgeons.
Joun

—v

ELECTED SINCE 1818. 511

Joun Lizars, Esq. Surgeon, Edinburgh.
Epwarp Hart, Esq. Chairman of the Board of Customs.
Joun Cay, Esq. Advocate.

April 2. 1821.
MEMBERS ELECTED.

Orpinary Memsers.

Sir Cuaries GiEsEcke’. Rosert Hamitton, M. D.
R. K. Grevitte, Esq. Edinburgh.

June 4. 1821.
MEMBERS ELECTED.

Orprnary.
Rosrrt Axian, Esq. Surgeon. Colonel Marr.
Honourable Lord Succorn. A. N. Carson, Esq.
Sir Davin Mixyz, Bart. Dr James Bucuay.

November 26. 1821.
OFFICE-BEARERS.
Sir Water Scort, Baronet, President.
Right Honourable Lor : ;
awe ae = erent Vice-Presidents,
Dr Brewster, General Secretary.
Tuomas Atay, Esq. Treasurer.
James Sxrnz, Esq. Curator of the Museum.
PHYSICAL CLASS.
Sir Grorce S. Macxenzin, Baronet, President.

ALEXANDER Irvine, Esq. Secretary,

VOI. IX. P. Ie 37 Counsellors

512 LIST OF OFFICE-BEARERS AND OF MEMBERS

Counsellors from the Physical Class.

Professor RusseExu. Henry Jarprne, Esq.
Dr Hope. Sir James Hatt, Bart.
Professor WALLACE. Dr Kennepy.

LITERARY CLASS.
Henry Mackenzie, Esq. President.
Sir Witt1am Hamirton, Bart. Secretary.

Counsellors from the Literary Class.
Sir Joun Hay, Bart. Reverend Mr Auison.
Reverend Dr D. Rrrcute. Tuomas Tuomson, Esq.
Right Hon. Lord Curer-Barox. Grorce Forses, Esq.

December 1. 1821.
MEMBERS ELECTED.
Orprnary Members.

James Tyrer, Esq. of Woodhouselee, W. S.

January 7. 1822.

MEMBERS ELECTED.

Foreign Memsers.
M. Ampere, Paris.
M. Van Swinven, Professor of Natural Philosophy,

Amsterdam.

M. Suumacuer, Professor of Astronomy, Copenhagen.

Orprnary Members.
Francis Cuantry, Esq. F. R. 5. Lond. &c.
Epwarp Trovcuton, Esq. F. R. 5. Lond.
James Situ, Esq. of Jordanhill.
Wiiu1aM Bonar, Esq.

Coin

ELECTED SINCE 1818. 513

Corin Macxenzir, Esq.
Rey. H. Parr Haminton.

February 4. 1822.
MEMBERS ELECTED.
Orpinary Memeens.
Captain J. D. Boswaiz, R.N. James Granam, Esq. Advocate.
Dr Joun Arrxin, Edinburgh. Grorce Waxker Arnort, Esq.

March 4. 1822.
MEMBERS ELECTED.
Forrien.
Professor Mous of Freyberg.
Orprinary.
Rev. Joun Lez, M.D. Edinburgh. Ricuarp Saumarez, Esq.
Joun Ayrton, Esq. of Inchdarnie.

June 3. 1822.
MEMBERS ELECTED.
Forgien.
Baron Larrey.
Orpinary.
James Sounu, Esq. F. R. S. London.
Lieutenant-Colonel Martin Wuyve.
W. F. Campzet, Esq. of Shawfield, M. P.
Grorcer Joseru Brun, Esq. Professor of Scots Law.
Dr Wiuu1am Dyce, Aberdeen:
WiC. Trevenxan, Esq.
302 November

514 LIST OF OFFICE-BEARERS AND MEMBERS

November 25. 1822.
OFFICE-BEARERS.
Sir Waurer Scott, Baronet, President.

Right Honourable Lord Gray, Peer eadon
Honourable Lord Genter. ;

Dr Brewster, General Secretary.
Tuomas Auuan, Esq. Treasurer.
James Skene, Esq. Curator of the Museum.
PHYSICAL CLASS.
Sir Georce S. Macxenziz, Baronet, President.

A exanber Irvine, Esq. Secretary.

Counsellors from the Physical Class.

Henry Jarpine, Esq. Dr Kennepy.
Professor WaLuace. Reverend Dr Macxnienr.
Sir James Hatt, Bart. Roszerr Srevenson, Esq.

LITERARY CLASS.
Henry Macxenzik, Esq. President.
Sir Wizt1am Hamitton, Baronet, Secretary.
Counsellors from the Literary Class.
Right Hon. Lord Curer-Baron. GrorceE Forzes, Esq

Reverend Dr Davin RitcuiE. Hon. Lord Mrapowsank.

Tuomas Tuomson, Esq. Professor Witson.

December 2. 1822.
MEMBERS ELECTED.
ORDINARY.
Dr Suorrt, Edinburgh.
Dr Waxticu, Calcutta.

Rosert ABERcROMBY, Esq.

younger of Birkenbog.

ELECTED sINCE 1818, : 515

February 3. 1823.
MEMBERS ELECTED.

Honorary.

M. Goerue.

Forricn Memsers.

M. De Canpottz, Geneva. M. Bronenrart, Paris.

Dr Oxzers, Bremen. The Chevalier Burc, Vienna.
The Bishop of ZEaLanp. M. Breisiax, Milan.
M, Orrant, Milan. M. Besse, Konigsberg.

M. Durr, Paris.

Orpinary Mempers.

Sir Grorce Warrenper, Baronet.

Joun Russet, Esq. W. S. Edinburgh.
Joun SHaw Stewart, Esq.

Dr Avexanper Haminton, Edinburgh.
Dr Tuomas Harxanp, Scarborough.
Joun Dewar, Esq. Advocate, Edinburgh.
Right Hon. Sir Wittram Rag, Baronet.
Sir Roserr Dunpas, Baronet.

Wi1am CabELL, Esq. of Cockenzie.

Sir Witu1am Knercuton, Baronet.

Sir Epwarp Frrencu Bromueap, Bart, A. M. F. B.S.

THE

516 LIST OF OFFICE-BEARERS AND MEMBERS, Xc.

‘Tue Law of the Society, No. xvm., having been altered, in
terms of the Charter, so as to authorise the election of two
Resident Vice-Presidents, these two offices were filled up on
the 3d February 1823, as follows :

Dr Tuomas Cuartes Hope, i Resident
Professor RussE.1, Vice-Presidents.

March 3. 1823.
MEMBERS ELECTED.
Orpinary.

Sir James Sruarr of Allanbank, Baronet.
Sir ANprew Haturpay, Knight, Physician to his Royal

Highness the Duke of Clarence.
Joun Bonar, Esq. younger of Kimmerghame.
ALEXANDER WapbELL, Esq.

LIST

pS (PASI)

LIST of the Present ORDINARY MEMBERS of the

1783.

1784.

1785.
1786.
1787.
1788.

1790.
1792.
1793.

ROYAL SOCIETY of EDINBURGH, in the Order of
their Election.

His Masesty THE KING
Patron.

Andrew Duncan senior, M. D. Professor of the Theory of Physic.

Dr James Hamilton senior, Physician, Edinburgh.

Sir William Miller, Baronet, Lord Glenlee.

James Russell, Esq. Professor of Clinical Surgery.

Charles Stuart, M. D. Physician, Edinburgh.

Dugald Stewart, Esq.

The above Gentlemen were Members of the Edinburgh Philosophical

Society.

Sir Ilay Campbell, Bart.

Honourable Lord Hermand.

Honourable Baron Hume.

Henry Mackenzie, Esq.

Honourable Lord Bannatyne.

Reverend William Trail, LL.D. Chancellor of St Saviour’s, Connor.

The above Gentlemen were associated with the Members of the Philoso-

phical Society at the Institution of the Royal Society in 1783. The
Members which follow were regularly elected.

Sir James Hall, Baronet, F. R. S. Lond.

Reverend Archibald Alison, LL.B.

James Hare, M. D. late of Calcutta.

Robert Blair, M. D. Professor of Practical Astronomy.

James Home, M. D. Professor of the Practice of Physic.

Thomas Charles Hope, M. D. F. R. S. Lond. Professor of Chemistry.

Right Honourable Charles Hope, Lord President of the Court of Session.

William Farquharson, M. D. Surgeon, Edinburgh.

Andrew Coventry, M. D. Professor of Agriculture.

Sir Alexander Muir Mackenzie, Bart. of Delvin.

518 LIST OF ORDINARY MEMBERS.

1795. The very Reverend Dr George Husband Baird, Principal of the University.
Robert Hamilton, Esq. Proféssor of Public Law.
1796. General Dirom of Mount Annan, F. R. S., Lond.
Reverend Sir Henry Moncreiff Wellwood, Bart.
The Honourable Baron Sir Patrick Murray, Baronet.
Andrew Berry, M. D. Edinburgh.
1797. Andrew Duncan junior, M. D. Professor of Materia Medica.
1798. Alexander Monro, M. D. Professor of Anatomy, &c.
Right Honourable Sir John Sinclair, Bart.
1799. Reverend Thomas Macknight, D. D.
Honourable Lord Robertson.
Sir George Mackenzie, Baronet, F. R. S. Lond.
Robert Jameson, Esq. Professor of Natural History.
1800. Sir William Arbuthnot, Bart.
Gilbert Innes, Esq. of Stow.
Sir Walter Scott, Baronet, of Abbotsford.
Reverend Andrew Bell.
Colonel W. Robertson Macdonald,
1803. Reverend John Jamieson, D. D.
Thomas Telford, Esq. Civil Engineer.
James Bryce, Esq. Surgeon, Edinburgh.
Reverend Dr Andrew Brown, Professor of Rhetoric.
1804. William Wallace, Esq. Professor of Mathematics.
General Vyse.
Sir William Forbes, Bart. of Pitsligo.
Alexander Irving, Esq. Professor of Civil Law.
1805. Thomas Allan, Esq. F. R. S. Lond.
Thomas Thomson, M. D. F. R. S. Lond. Proféssor of Chemistry, Glasgow.
1806. Robert Ferguson, Esq. of Raith, F. R.S. Lond.
George Bell, Esq. Surgeon, Edinburgh.
George Dunbar, Esq. Professor of Greek.
1807. Sir James Montgomery, Baronet, of Stanhope, M. P.
John Barclay, M. D. Lecturer on Anatomy, &c.
John Leslie, Esq. Professor of Natural Philosophy.
John Campbell, Esq. of Carbrook.
Thomas Thomson, Esq. Advocate.
William Fraser Tytler, Esq. Advocate.
1808. James Wardrop, Esq. Surgeon Extraordinary to his Majesty.
David Brewster, LL.D. F.R.S. Lond.
1810. Reverend Dr William Ritchie, Professor of Divinity.
1811. Charles Bell, Esq. Surgeon, London.
Alexander Nimmo, Esq. Civil Engineer.

1811.

1812.

1813.

1814.

1815.

1816.

LIST OF ORDINARY MEMBERS: 519

Reverend Andrew Stewart, M.D. Blantyre.

Reverend David Ritchie, D.D. Professor of Logic.

His Excellency Sir Thomas Brisbane, K.C. B. Governor of New South
Wales.

Right Honourable Lord Gray, F.R.S. Lond.

General Dyce.

John Thomson, M. D. Physician, Edinburgh.

James Jardine, Esq. Civil Engincer.

Captain Basil Hall, R. N. F. R.S. Lond.

J. G. Children, Esq. F. R.S. Lond.

Alexander Gillespie, Esq. Surgeon, Edinburgh.

W. A. Cadell, Esq. F. R. S. Lond.

Macvey Napier, Esq. F. R.S. Lond.

James Millar, Esq. Professor of Humanity.

Sir George Clerk, Bart. M. P. and F. R.S. Lond.

Daniel Ellis, Esq.

William Sommerville, M. D. F. R.S. Lond.

James Hare, jun. M. D. late of Calcutta.

Henry Davidson, M. D. Physician in Edinburgh.

Henry Jardine, Esq. King’s Remembrancer in Exchequer.

Patrick Neill, Esq. Secretary to the Wernerian and Horticultural Societies.

Right Honourable Lord Viscount Arbuthnot.

Reverend John Thomson, Duddingston.

Reverend John Fleming, D, D. Flisk.

John Cheyne, M. D. Physician, Dublin.

Sir James Mackintosh, Knight, M. P.

Lieut.-Colonel Tytler.

Reverend Alexander Brunton, D. D. Proféssor of Oriental Languages.

Professor George Glennie, Marischall College, Aberdeen.

Gilbert Laing Meason, Esq. of Lindertis.

Robert Stevenson, Esq. Civil Engineer.

Sir Thomas Dick Lauder, Bart. of Fountainhall.

John Yule, M. D. Physician in Edinburgh.

Henry Home Drummond, Esq. of Blair-Drummond, M. P.

Charles Granville Stewart Menteath, Esq. of Closeburn.

William Thomas Brande, Esq. F. R.S. Lond. and Professor of Chemistry
in the Royal Institution.

Major Thomas Colby, Royal Engineers.

Leonard Horner, Esq. F. B.S. Lond.

Henry Colebrooke, Esq.

Reverend George Cook, D. D. Laurencekirk.

VOL. IX. P. II. 3uU

or
2
>)

LIST OF ORDINARY MEMBERS.

Right Honourable William Adam, Lord Chief Commissioner.
John Fullerton, Esq. Advocate.
Thomas Jackson, LL.D. Professor of Natural Philosophy, St Andrews .
John Robison, Esq.
Hugh Murray, Esq.
1817. The Honourable Baron Clerk Rattray.
Right Honourable the-Earl of Wemyss and March.
Francis Hamilton, M. D. F.R. S. and F. A. S. Lond.
John Wilson, Esq. Professor of Moral Philosophy.
Honourable Lord Meadowbank.
John Fleming, M. D: date of Calcutta.
James Hamilton Dickson, M. D. Clifton.
William P: Alison, M. D. Professor of the Theory of Physic:
James Skene, Esq. of Rubislaw.
John Howel, M. D:
Reverend Robert Morehead, Edinburgh.
Robert Bald, Esq. Civil Engineer.
Thomas Sivright, Esq. of Meggetland.

1818. William Richardson, M. D. Physician, Harrowgate.
Honourable Captain William Napier of Merchiston, R. N.
Harry William Carter, M. B. Oaford. ‘

Patrick Miller, M. D. Ezeter.

John Craig, Esq. Edinburgh.

John Watson, M. D.

Captain Thomas Brown, F. L. S.

John Hope, Esq. His Majesty's Solicitor-General.
Major James Alston of Auchenard.

William Ferguson, M. D. Windsor.

Sir William Hamilton, Bart. Professor of Civil History.

1819. Right Honourable Lord John Campbell, F. R.S. Lond, and M. R. L..
Sir John Hay, Bart. of Smithfield and Hayston.

Dr Shoolbred, Calcutta.

Patrick Fraser Tytler, Esq. Advocate.

Colonel David Stewart of Garth.

Patrick Murray, Esq. of Simprim.

James Muttlebury, M. D. Bath.

Thomas Stewart Traill, M. D. Liverpool:
Alexander Kennedy, M. D. Physician, Edinburgh.
Mr Alexander Adie, Optician; Edinburgh.
William Couper, M. D. Glasgow

1821.

LIST OF ORDINARY MEMBERS. §21

John Hennen, M. D.

John Veitch, M. D.

Andrew Waddel, Esq. Hermitage Hill.
Marshall Hall, M. D. Nottingham,
John Borthwick, Esq. Advocate.
Richard Phillips, Esq. London.

William Scoresby, Esq. jun. Liverpool.
George Forbes, Esq. Edinburgh.

. James Hunter, Esq. of Thurston.

Right Honourable David Boyle, Lord Justice-Clerk.

James Keith, Esq. Surgeon, Edinburgh.

Right Honourable Sir Samuel Shepherd, Lord Chief-Baron.
James Naime, Esq. W. S. Edinburgh.

John Colquhoun, Esq. Advocate.

Sir Henry Raeburn, Knight.

Lieutenant-Colonel M. Stewart.

Charles Babbage, Esq. F. R..S. Lond.

Thomas Guthrie Wright, Esq. Auditor of the Court of Session.
John F. W. Herschel, Esq. F. R. S. Lond.

Adam Anderson, Esq. A. M. Rector of the Academy, Perth.
John Shank More, Esq. Advocate.

William Hall, Esq. A. M.

Dr George Augustus Borthwick, Swrgeon, Edinburgh.
Robert Dundas, Esq. of Arniston.

Samuel Hibbert, M. D. Edinburgh.

Rev. Robert Haldane, D. D. Principal of St Mary's College, St Andrew's.
Sir John Meade, M. D. Weymouth.

Thomas Kinnear, Esq. Edinburgh.

Dr William Macdonald. of Ballyshear .

John Hay, Esq. younger of Smithfield and Hayston.
Captain Robert Hay, R. N.

George Ballingall, M. D. Proféssor of Military Surgery.
Lieutenant-Colonel Straton, C. B., &c. &c.

Robert Graham, M. D. Professor of Botany.

A. N. Macleod, Esq. of Harris.

Sir James M. Riddell, Bart. of Ardnamurchan.

Archibald Bell, Esq. Advocate.

John Clerk Maxwell, Esq. Advocate.

The Right Honourable the Earl of Hopetoun, G. C. B.
John H. Wishart, Esq. Surgeon, Edinburgh.

John Lizars, Esq. Surgeon, Edinburgh.

30 12

522

1823.

LIST OF ORDINARY MEMBERS.

Edward Earl, Esq. Chairman of the Board of Customs.
John Cay, Esq. Advocate.

Sir Charles Giesecké, Professor of Mineralogy to the Dublin Society.
Robert Kaye Greville, Esq. Edinburgh.

Robert Hamilton, M. D. Edinburgh.

Robert Allan, Esq. Swrgeon, Edinburgh.

Honourable Lord Succoth.

Sir David Milne, Bart.

Colonel Mair, Deputy-Governor of Fort George.

A. N. Carson, Esq. Rector of the High School.

James Buchan, M. D. Physician, Edinburgh.

James Tytler, Esq. of Woodhouselee, W. S.

. Francis Chantry, Esq. F. R. S$. Lond. &c.

Edward Troughton, Esq. F. R. S. London, &e.
James Smith, Esq. of Jordanhill.

William Bonar, Esq. Edinburgh.

Colin Mackenzie, Esq. Deputy Keeper of the Signet:
Rev. H, Parr Hamilton, Cambridge.

Captain J. D. Boswall, Ri N. of Wardie.

Dr John Aitkin, Physician, Edinburgh.

James Graham, Esq. Advocate.

George A. Walker Arnott, Esq. Advocate.

Rev. John Lee, M: D. Edinburgh.

John Ayton, Esq. of Inchdarnie.

Richard Saumarez, Esq.

James South, Esq. F. R. S. Lond.
Lieutenant-Colonel Martin Whyte, Edinburgh.
Walter Frederick Campbell, Esq: of Shaw/ield, M. P.
George Joseph Bell, Esq. Professor of Scots Law.
Dr William Dyce, Aberdeen.

W. C. Trevelyan, Esq. Wallington.

Robert Abercromby,, Bsq: youngen of Birkenbog.

Dr Shortt, Edinburgh.

Dr Wallich, Calcutta.

The Right Honourable Sir George Warrender, Bart. of Lochend.
John Russell, Esq. Wi. S» Edinburgh:
John Shaw Stewart, Esq. Advocate.

Alexander Hamilton, M. D. Physician, Edinburgh.

‘Thomas Harland; M. De Physician, Scarborough.

John Dewar, Esq. Advocate, Edinburgh:
Right Honourable Sir William Rae, Bart: of S# Catharine’s, Lord Advocate.
Sir Robert Dundas, Bart.

LIST OF ORDINARY MEMBERS. 528

William Cadell, Esq. of Cockenzie.

Sir William Knighton, Bart.

Sir Edward French Bromhead, Bart. A. M. F.R.S. Lond., Thurlsby Hall.

Sir James Stuart, Bart. of Allanbank.

Sir Andrew Halliday, Knight, Physician to His Royal Highness the Duke
of Clarence.

John Bonar, Esq. younger of Kimmerghame.

Alexander Waddell, Esq.

LIST

( 524 )

LIST of NON-RESIDENT and FOREIGN MEMBERS,
elected under the Old Laws.

Sir Gilbert Blane, M. D. F. R. S. London.

John Hunter, LL. D. Professor of Humanity, St Andrew's.
George Jardine, A. M. Professor of Logic, Glasgow.

John Rogerson, M. D. of Wamphray.

Right Honourable the Earl of Morton, K. E.

Right Honourable the Earl of Dundonald.

Right Honourable Sir Robert Liston, Bart.

The Most Noble the Marquis of Lothian, K. T.

Mr Jefferson.

M. Le Chevalier, Paris.

Dr S. L. Mitchill, New York.

Right Honourable Thomas Wallace, Esq. of Carlton Hail.
Reverend Thomas Somerville, D. D. Jedburgh.

John Gillies, LL.D. Historiographer to his Majesty.

Robert Freer, M. D. Professor of the Theory and Practice of Physic, Glasgow.

M. A. Pictet, Geneva.

M. P. Prevost, Geneva.

Rev. Walter Fisher, Cranston.

Reverend Bishop Gleig, Stirling.

Charles Hatchett, Esq. F. R. S. Lond.

Major Rennel, F. R.S. Lond.

Sir Henry Stuart, Bart. of Allanton.

Matthew Baillie, M. D. London.

Sir William Blizzard, M. D. F. R. S. London.
Thomas Blizzard, Esq.

Sir William Ousely, Bart.

The Right Honourable the Earl of Traquair.
Sir William Drummond, Bart. of Logie-Almond.
Sir John Macgregor, M.D.

Richard Chenevix, Esq. F. R. S. Lond.

Right Honourable Lord Glenbervie.

Richard Griffiths, Esq. Civil Engineer.

——s

( 525 )

LIST of HONORARY and FOREIGN MEMBERS,
elected under the New Laws.

HONORARY.

The Marquis Laplace, Member of the Institute of France.
Baron Cuvier, Secretary to the Institute of France.

M. Humboldt, Member of the Institute of France.

Sir Humphry Davy, Bart. P. R. S:; Lond.

M. Gay Lussac, Member of the Institute of France..

M. Biot, Member of the Institute of France.

M. Arago, Member of the Institute of France.

His Royal Highness Prince Leopold.

His Royal Highness the Archduke Maximilian.

Count Itterburg.

The above Members were elected before the new class of Foreign Members was
established.

His Imperial Highness the Archduke John.
M. Le Chevalier Joseph Hammer.
M. Goethé.

FOREIGN.

M. Le Chevalier Legendre, Member of the Institute of France.
M. Poisson, Member of the Institute of France.

M. Vauquelin, Member of the Institute of France.

M. Prony, Member of the Institute of France.

M. Brochant, Member of the Institute of France.

Baron Leopold Von Buch, Berlin. ;

™M. Gauss, Professor of Mathematics, Gottingen.

M. Blumenbach, Professor of Natural History, Gottingen.
Jacob Berzelius, M.D. F. R. S. Lond. Professor of Chemistry, Stockholm.
Count Volta, Como.

M. J. C. L. Simonde de Sismondi.

Baron Degerando.

526 LIST OF HONORARY AND FOREIGN MEMBERS.

Baron Krusenstern, Member of the Academy of Sciences at St Petersburg.

M. Oersted, Secretary to the Royul Society of Copenhagen.

M. Ampere, Member of the Institute of France.

M. Van Swinden, Professor of Natural Philosophy, Amsterdam.

M. Shumacher, Professor of Astronomy at Copenhagen.

M. Mohs, Professor of Mineralogy at Freyberg.

M. Kaussler, St Petersburg.

David Hosack, M. D. F.R.S. New York.

Nathaniel Bowditch, Esq. Salem, Massachusets.

Baron Larrey, Member of the Institute of France.

Sir Henry Bernstein, Professor of Oriental Literature in the University of Berlin.
M. De Candolle, Geneva.

Dr Olbers, Bremen.

The Bishop of Zealand, Copenhagen.

M. Oriani, Milan.

M. Dupin, Member of the Institute of France.

M. Brongniart, Member of the Institute of France.
The Chevalier Burg, Vienna.

M. Breislak, Milan.

M. Bessel, Konigsberg.

LIST

{< 587°)

LIST of Deceased Members from 1799 to March 1. 1823,—Continued
Srom Vol. IV. p. 37. *

Noy. 15.

26.

June 19.

1799.

Rev. Dr Thomas Robertson,

Dalmeny.
Dr Joseph Black.
Commissioner Edgar.

1800.

. Mr Jesse Ramsden.
. Baron Gordon.

. Dr Hugh Blair.

- William Tait, Esq.

William Hall, Esq.
Alex. John Alexander, Esq.

1801.
Andrew Lumsden, Esq.
Dr Richard Pulteney.
Lord Stonefield.

1803.

. John Macgowan, Esq.
. General Fletcher.
. Sir James Montgomery, Bart.

Lord Chief-Baron.

. Sir William Hamilton, Bart.
. John Grieve, Esq.

. Robert Kennedy, M. D.

. Dr Beattie.

Mr J. Lindsay, Jamaica.

. Robert Arbuthnot, Esq.

J. Robertson, Register-Office.
Professor Baron, St Andrew’s.
. Rev. Dr Walker.

. Sept. 4

1805.
Professor John Robison, LL.D.
Rev. Dr Carlyle.
Professor John Hill, LL.D.

Jan. 30.
Aug. 28.
Dec. 7.

1806.
Benjamin Bell, Esq.
Sir William Forbes, Bart.

April 4.
Nov. 10.

Dec. 8. Professor Andrew Dalzell.
1807.
Mar. 22. John Morthland, Esq.
May 25. Professor. Nicolas Vilant.
Aug.30. Mathew Guthrie, M.D. St Pe-
tersburg.
1808.

Jan. 28. Dr James Finlayson, Profes-
sor of Logic.

Rev. Dr Alex. Small, Dundee:

John Home, Esq.

Dr James Anderson.

Aug. 23.
Oct. 15.

1809.
Dr John Hunter.
Right Hon. The Earl of Dun-
more.
Apr. 22. Rev. Dr Andrew Hunter, Pro-
fessor of Divinity.

May 8. Dr Alexander Hunter.

22. Dr Hugh Macleod.
Aug. 8. Dr Andrew Mackay.

17. Matthew Boulton, Esq.

Feb. 17.
Mar. 5.

* This List is very imperfect, in consequence of no record of Deceased Members having been kept; but _

it contains the names of most of those Members who contributed to the prosperity of the Society.

VOL. IX. P. Il.

ox

Feb. 3.
9.
Mar. 23.

May 10.

20.
29.

LIST OF DECEASED MEMBERS.

General Robert Melville.
Caleb Whiteford, Esq.

1810.
Dr James Anderson.

. Honourable Lord Cullen.

Bartholomew Parr, M.D. Exe-
ter.

. James Flint, M.D. St Andrew’s.

Sir James Grant, Bart.

1811.

Dr John Rutherford.

Rey. Dr Maskelyne.

Sir William Nairne, (Lord
Dunsinnan).

Dr Anderson, St Vincent's.

Lord President Blair.

Right Hon. Lord Viscount Mel-
ville.

. P. Simon Pallas, M. D.
. John Burnet, Esq.

1812.

. Dr Maxwell Garthshore.

John Clerk, Esq. of Eldin.

. Richard Kirwan,Esq.
. Rev. Dr William Moodie, Pro-

fessor of Oriental Languages.

1813.

. The Hon. Alexander Fraser

Tytler, Lord Woodhouselee.

. M. Le Comte Lagrange.
. Rev. Alex. Murray, D. D.

Honourable Lord Craig.

1814.

Right Hon. The Earl of Minto.

Rev. Walter Young, D. D.
Count Rumford.

1815.

Jan. 11. Right Hon. Lord Seaforth...

Jan. 14, William Creech, Esq.
Feb. 19. Dr William Roxburgh.

1816.

Feb. 22. Dr Adam Ferguson,
May 29. Right Hon. James Earl of

Hopetoun.

June 14. Honourable Alan Maconochie,

Lord Meadowbank.

1817.

May 30. Dr William Saunders.
June 30. James Glenie, Esq. F. R..S..

June 30. Professor Werner of Freyberg.
Sep.

Lond.

3. James Byres, Esq.

Sept. 18. Dr Wells.

Oct.

Jan.

2. Dr Alexander Monro.

1818.
24. Robert Beatson, LL.D.

June 14. Dr John Gordon.

June 19. Patrick Brydone, Esq.
Aug. 30. Robert Wilson, Esq.

Dec. 12. Sir John Henderson, Bart.

1819 .

Feb. 14. Professor William Ogilvie.

17. George Ranken, Esq.
26. Alexander Keith, Esq.

Aprill19. Right Hon. Lord Webb Sey-

mour.

May 26. Rev. Principal Playfair.
June 17. Lord Chief-Baron Dundas.

24, SirGeorge Buchan-Hepburn,

Bart.

July 20. Professor Playfair.
Aug. 18. Adam Rolland, Esq.

25. James Watt, Esq.

=.’

LIST OF DECEASED MEMBERS. 529

Sept. 19. Dr William Wright. July 9. William Douglas, Esq.
Dec. 15. Dr Daniel Rutherford. Aug. 29. James Robinson Scott, F. L. S.
Dec. 19. Rev. Principal Hill. June 18. Professor Cleghorn.
Oct. 4. John Rennie, Esq.
1820.
April 1. Right Hon. the Earl of Sel- 1822,
kirk. Mar. 27. Sir Alexander Boswell, Bart.
April 2. Dr Thomas Brown. The Abbé Haiiy.
June 19. Honourable Baron Norton. Aug. 19. M. Le Chevalier Delambre.
20. Sir Joseph Banks, Bart. Sept. 30. Hay Donaldson, Esq. W. S.
June 22. Dr John Murray. Oct. 19. Tho. Mackenzie, Esq. of Apple-
25. Professor Christison. cross, M. P.
Nov. 13. Lieutenant-Colonel Imrie. Nov. ‘7. James Wedderburn, Esq. His
18. Professor John Young. Majesty’s Solicitor-General.
Nov. 10. Dr Patrick Copland.
1821.
Mar. 25. James Bonar, Esq. 1823.
April 2. Dr James Gregory. Jan. 19. Dr Henry Dewar.
12. Alexander Oswald, Esq. Feb. 10. Charles Hutton, LL.D., F. R. 8.

3x2 PRESENTS

1812.

( 530 )

PRESENTS received by the ROYAL SOCIETY
of EDINBURGH since 1811.

PRESENTS.

- American Mineralogical Journal, Nos. Ist, 2d,

and 3d. Edited by Dr Bruce.

Inquisitionum ad Capellam Domini Regis Re-
tornatarum, &c. Abbreviatio, in 3 volumes
folio.

Memoirs of the Wernerian Natural History So-
ciety of Edinburgh, vol. Ist.

On the Mineralogy of the Vicinity of Dublin,
London, 1812, by W. Fitton, M. D.

Reports on the General Management of Arable
Lands, by Robert Kerr, M. D.

Agricultural Report of Berwickshire, by Ro-
bert Kerr, M.D.

Report respecting the supply of Water to the
City of Edinburgh.

Du Calorique Rayonnante, par M. P. Prevost.

A Collection of specimens of Flints.

On Scottish Gardens and Orchards, by Patrick _

Neill, Esq.

. Memoirs of the Literary and Philosophical So-

ciety of Manchester, vol. 2d of the 2d series.

Agricultural Report of Berwickshire, and Sketch
of ageneral Report respecting the Agricul-
ture of Scotland, by Mr Kerr.

. The Head and Horns of a large Animal of the

Ox kind, found in a moss near Dunse.

. Transactions of the Royal Society of London,

part 2d for 1811, vol. for 1812, and part 1st
for 1813.
Transactions of the Philosophical Society of
Manchester, vol 2d of the new series.
Journal des Mines, from July 1811 to June
1812.

DONORS.
Dr Bruce.

The Commissioners of

Public Records.

The Wernrerian Natural
History Society.
Dr Fitton.

Dr Robert Kerr.

Dr Robert Kerr.

Thomas Allan, Esq.

M. P. Prevost.

Thomas Allan, Esq.

Patrick Neill, Esq.

The Literary and Philo-
sophical Society of
Manchester.

The Author.

Mr Watson of Dunse.

The Royal Society of
London.

The Philosophical Society
of Manchester.
Thomas Allan, Esq.

Dec. 19.

LIST OF DONATIONS.

PRESENTS.

Translation of Daubuisson’s account of the Ba-
salts of Saxony, by Mr Neill.

18. Treatise on New Philosophical Instruments, by

1815.

Feb. 20.

Dee.

18.

Dr Brewster.
Werner’s Nomenclature of Colours, with addi-
tions, by Mr Patrick Syme, Edinburgh, 1821.

7. Mémoires de Academie Imperiale des Sciences

de St Petersburg, vols. Ist, 2d, and 3d.

Memoirs of the Wernerian Natural History So-

ciety, vol. 2d. part Ist.
Account of the Life and Writings of Dr Robert
Simson, by the Rev. Dr Trail.

. The Transactions of the Royal Danish Society,

from 1781 to 1808, 5 vols. 4to.

Transactions of the Royal Society of Copenhagen,

vols. 2d, 3d, 4th, and 5th, 4to. from 1783 to

1799.

The Transactions of the Geological Society of
London, vols. 1st and 2d.

A Drawing and Description of a remarkable Pe-
trifaction found near Ardrossan.

Treatise on the Diuretic Properties of the Pyrola
umbellata, by Dr Somerville.

List of Mineralogical Synonimes and Analyses, by
Thomas Allan, Esq.
Notitia Collectionis Vermium.

Mémoires de I’ Academie Imperiale des Sciences de
St Petersburg, vol. 4th.

. A Collection of Minerals.

An Account of a Stone which fell from the At-
mosphere near Bombay, translated from the
Persian.

The Acts of the Parliament of Scotland, vols. 2d

and 3d.
Registrum Magni Sigilli Scotiz.

Reports of the Pestilential Disorder in Andalusia,
by Sir James Fellowes, M. D. Lond. 1815.

. The Materia Medica of Hindostan, 1 vol. 4to:

Madras, 1813.

The Hunterian Oration, by Sir William Blizzard,
Knight.

The Transactions of the Literary and Philosophi-
cal Society of New York, vol. 1st. 4to.

531

DONORS.

Patrick Neill, Esq.
Dr Brewster.
Mr Blackwood.

The Royal Academy of
Sciences of St Peters.
burgh.

The Wernerian Natural
History Society.

Rev. Dr Trail.

Sir George S. Mackenzie,
Baronet.

Sir George S. Mackenzie,
Baronet.

The Geological Society of
London.
The Earl of Eglinton.

Dr Somerville.

Thomas Allan, Esq.

From the Museum of Na-
tural History at Vi-
enna.

The Royal Academy of
Sciences of St Peters
burgh.

Captain Basil Hall.

Captain Basil Hall.

Commissioners of the Pu-
blic Records.

Commissioners of the Pu-
bli- Records,

SirJames Fellowes, M, D.

Dr Ainslie.
Sir William Blizzard.
The Literary and Philo-

sophical Society of New
York.

1816.
Jan. 8.

Apr. 15.

May 20.

Q7.

Nov. 17.

1817.
Jan. 20.

Feb. 3.

17.

Mar. 3.

May 5.
Nov. 17.

1818.
Jan. 12.

LIST OF DONATIONS.

PRESENTS.

Elegiorum Sepulchralium Edinensium delectus.
Wood’s General Conchology, 1 vol. 8vo, London,
1815.

The American Medical and Philosophical Regis-
ter, 8 volumes.

Recherches sur Acide Prussique, par M. Gay
Lussac, Paris, 1815.

A Treatise on Universal Grammar, drawn up for
the Edinburgh Encyclopedia, by Dr Henry
Dewar.

The Koran in Arabic.

Treatise on Dew, by Dr Wells, second edition.

The Transactions of the Geological Society of
London, vol. 3d.

The Map of Cornwall, Devonshire, and Isle of
Wight, published by the Board of Ordnance.

Asiatic Researches, vol. 12th.

The Transactions of the Geological Society of
London, part 1st of vol. 4th.

The Acts of the Parliaments of Scotland, vol. 4th.

Developement de Geometrie, with the report of the
Institute upon it.

Examen des Operations et des Travaux de Czx-
sar.

Two gold coins, one of King James the First, and
the other of King James the Second.

A Treatise on Arithmetic and Geometry, being a
translation of the work of Bhascara Acharya.
A Meteorological Chart, exhibiting the variations

in the barometer, and the quantity of rain.

The sheets lately published of the Ordnance Map
of Great Britain.

A specimen of Tabasheer from Nagpore.

An Experimental Inquiry into the Laws of the
Vital Functions, by Dr Wilson Philip.

The Transactions of the Geological Society of
London, vol. 4th.

An Ink-stand, composed of a variety of British
woods. :

On the Vital Functions and Internal Diseases,
1 vol. 8vo. Lond. 1817, by A. P. Wilson Philip,
M. D.

Transactions of the Linnean Society, vol 11th.

The Philosophical Transactions for 1817, part
2d.

DONORS

Dr Duncan sen.
Mr Wood.

Drs Hosack and Francis,
the Editors.
M. Gay Lussac.

Dr Henry Dewar.

General Macleod of Mac-
leod.

Dr Wells.

The Geological Society
of London.

Captain Colby.

The Asiatic Society of
Calcutta.
The Geological Society
of London.
The Commissioners of
Public Records.
M. Dupin.

M. Dupin.

The Barons of Exche-
quer.

Dr John Taylor.

Right Hon. Lord Gray.

Captain Colby.

Alex. Kennedy, M. D.
Dr Wilson Philip ;

The Geological Society
of London.
Mr George Bullock.

Dr Wilson Philip.

The Linnean Society.

The Royal Society of
London,

LIST OF DONATIONS.

1818.

Jan. 19. A Report of a Committee of the Linnean Soeiety
of New England, relative to a large marine
animal.

Feb. 2. The Ordnance Map, No. 7.

Memoirs of the Wernerian Natural History Socie-
ty, part 2d of vol. 2d.

2. Observations Entomologiques.

PRESENTS.

Mar.
Apr. 6. Voyage of Discovery to the West Coast of Corea,
and the Great Loo-Choo Island, by Captain
Basil Hall. ‘
Apr. 20. A coloured picture, exhibiting the Meteorological
history of the last year.
An Essay on the Origin and Operation of the Dry
Rot, by Robert Maewilliam, architect and sur-
veyor.
May 4. The Transactions of the Society of Scottish An-
tiquaries, part Ist of vol. 2d.

June 1. Acts of the Parliaments of Scotland, vol. 5th.
Nov. 10. A specimen of the Worm found in the Eye of

Horses in the East Indies.
Flora Batava, No. 52.

Dec. ‘7. Histoire du Passage des Alpes, par De Luc.
21 Deux Traités de Physique Mecanique, par M.
é Pierre Prevost. :
Histoire du Passage des Alpes par Annibal, by
J. A. Deluc.
Several Mathematical Tracts, by Mr Nathaniel
Bowditch.
1819.

Feb. 15. Memoirs. of the American Academy of Arts and
Sciences at’ Boston, part Ist of vol. 4th.

Mar. 15. Essay on the-external application of Vapour to the
human frame, by Professor Aldini.
Apr. 5. The Ordnance Map, part 8th.

Noy. 15. A critical examination of the first principles of
Geology, by G. B. Greenough, Esq. President
of the Geological Society of London.
Thenard’s Essay on Chemical Analysis, translated
by J. G. Children, Esq.
A sketch of the Economy of Man, by Dr Nicholl
of Ludlow, 1 vol. 8vo.

Flora Batava, No. 53, 54, 55.

Dec. 6. Memoirs of the Literary and Philosophical Socie-

ty of Manchester, vol. 3d.

538

DONORS.

The Linnean Society of
Boston,

Captain Colby.

The Wernerian Natural
History Society.

M. Bonelli of Turin.

Captain Basil Hall.

Lord Gray.
Mr Maewilliam.

The Society of Scottish
Antiquaries.

The Commissioners of the
Public Records.

Alexander Kennedy, Esq.

His Majesty the King of
the Netherlands.

M. P. Prevost.

M. P. Prevost.

M. J. A. Deluce.

Mr Bowditch.

The American Academy.
of Arts and Sciences at
Boston.

Professor Aldini.

Captain Colby.

G. B. Greenough, Esq.

J. G. Children, Esq.
Dr Nicholl.

His Majesty the King of
the Netherlands.
The Literary and Philo.
sophical Society of
Manchester.

20.

1820.

Jan.
Feb.
Apr.

June

ie
T.
3.

5.

22.

LIST OF DONATIONS.

PRESENTS.

DONORS.

Specimens of Native Hydrate of Magnesia, found Dr Samuel Hibbert.

in Shetland, and described in the Transactions,
vol. 9th, p. 239.

Sculptures of Indian Idols, described in the Tran- Francis Simpson, Esq.

sactions, vol. 9th, p. 381.

Essai Historique sur les Services et les Travaux
scientifiques de Gaspard Monge.

Silliman’s American Journal of Science, Nos. Ist,
2d and 3d.

Transactions of the Linnean Society, vol. 12th.

The Acts of the Scottish Parliament, vol. 6th.

A Treatise on Physical Astronomy, by Mr Ro-
bert Kerr of Douglas, Isle of Man.

Histoire Naturelle et Medicale de Casses, par L.
Theod. Fred. Colladon, 4to, Montpellier, 1816.

A specimen of Sandstone from Craigleith Quarry,
near Edinburgh, exhibiting a vegetable impres-
sion of the Palm tribe, with rudiments of buds
or flowers.

The Acts of the Parliaments of Scotland, vol. 7th.

. The Ordnance Maps of the Counties of Kent and

Pembroke.

Memoirs of the Royal Academy of Sciences at
Turin, 20 vols.

Memorie di Matematica e Fisica della Societa Ita-
liana, 18 vols.

Voyages dans la Grande Bretagne, 2 vols. 4to.,
par M. Dupin.

Progrés des Sciences et des Artes de la Marine
Francaise, depuis la paix, par M. Dupin. Paris,
1820.

Essai Geologique sur Ecosse, par Dr A. Boué.

Visiteur des Pauyres, et Programme de cours de
Droit Publique, par M. Degerando.

Mémoire sur la combinaison de l’oxigtne avec

Peau, par M. Thenard.

. Flora Batava, No. 56.

. Characters of the classes, orders, genera and spe-

cies of Minerals, by M. Frederick Mohs.
The Acts of the Parliament of Scotland, vol. 8th.

. An Essay on subjects connected with Taste, by

Sir G. S. Mackenzie, Bart.

Illustrations of Phrenology, by Sir G. S, Mac-
kenzie, Bart.

Flora Batava, No. 57.

M. Dupin.

Thomas Allan, Esq.
The Linnean Society.

The Commissioners of
the Public Resords.
Mr Robert Kerr.

Dr Colladon.
Thomas Allan, Esq.

The Commissioners of the
Public Records.
Captain Colby.

The Royal Academy of
Sciences at Turin.

His Royal Highness the
Archduke Maximilian.

M. Dupin.

M. Dupin.

Dr A. Boué.
M. Degerando.

M. Thenard.

His Majesty the King of
the Netherlands.
M. Frederick Mohs.

Commissioners of the
Public Records.

Sir G. S. Mackenzie,
Bart.

Sir G. S. Mackenzie,
Bart.

His Majesty the King of
the Netherlands.

>

EEE

‘1821.
“Mar. 19.

Apr. 2.

16.

May 7.

June 4.

Noy. - 5.

LIST OF DONATIONS.

PRESENTS.

A Meteorological Journal, kept at Delvin by Miss
Margaret Mackenzie of Dolphinton, from 1780
to 1802.

A large specimen of Madrepore from Bermuda.

Specimens of Fossil Shells, bent and contorted.

A View of the structure of the Stomach and Ali-
mentary Organs, by Mr Thomas Hare, 8vo.

Mémoires sur l’Action mutuelle des deux courans
electriques, par M. Ampere.
Flora Batava, No. 58.

Transactions of the Cambridge Philosophical So-
ciety, part Ist of vol. Ist.

Astronomische. Hulfstaflen, for 1821; by, Professor
Schumacher of Copenhagen.

Transactions of the Historical and Literary Com-
mittee of the American Philosophical Society.

Heckewelder’s Narrative of the Missions of. the

United Brethren among the Delaware and Mo- ,

hegan Indians.

Memoirs. of the Institute of France since 1810,
13 vols.
Flora Batava, No. 59.

Acta Literaria Societatis Rheno-Trajectine, 4 vols.
Utrecht, 1793,—1803.

Essays and Tracts printed by the Society of Sci-
ences of Utrecht, 9 parts.

Transactions of the Literary and Scientific Society
of Utrecht, in Dutch, 9 vols. 1781-1803.

Disquisitio de Decompositione Acidi-Carbonici in
Vegetatione, Richardi Van Rees, premio ornata,
Utrecht 1818.

Oratio de vitanda, in Astronomiz studio, fingendi
temeritate, et Coceli-Observatione quam .diligen-
tissime instituenda, Gerardi Moll.

Histoire de l’Astronomie Ancienne, 2 vols. par M.
Delambre. ;

Histoire de l'Astronomie du Moyen Age, 1 vol.

par M. Delambre.

Histoire de |Astronomie Moderne; par M. De-

1822.
Jan. 21.

VOL. IX, P: II.

lambre.
Asiatie Researches, vol. 13th.
A Sanscrit, Manuscript.

‘Transactions of the; Society of Arts, 35 vols,
Description of the Shetland Islands, by Dr Hibbert.

3 Y

535

DONORS.

James Hunter, Esq. of
Thurston.

The . Marchioness of
Huntly.

Mr Andrew Flint, civil
engineer.

Mr Thomas Hare.

M. Ampere.

His Majesty the King of
the Netherlands.

The Cambridge Philo-
sophical Society.

Professor Schumacher.

The American Philoso-
phical Society.

The American Philoso-
phical Society.

The Institute of France.

His Majesty the King of
the Netherlands.

The Literary and Scien-
tific Society of Utrecht.

The Literary and Scien-
tific Society of Utrecht.

The Literary and Scien-
tific Society of Utrecht.

M. Van Rees.

Prof, Moll of Utrecht.

M. Je Cheyalier Delam-

bre.

M. le Chevalier Delam-
bre.

M. le Chevalier Delam-
bre.

The Asiatic Society.

James Macpherson, Esq.

-of Belleville.
The Society of Arts,
Dr Hibbert.

LIST OF DONATIONS.

PRESENTS.

Mr Goodwyn’s Introduction to a Synoptical Table
of Measures.

Memoirs of the American Academy of Arts and
Sciences, part 1st of vol. 4th.

Register of the Barometer, Thermometer, and Tem-
perature of Springs for 1821, kept at Huntly
Lodge, by Mr Alexander Murdoch.

Register of the Barometer, Thermometer, and
Temperature of Springs for 1821, kept at the
Royal Academy, Inverness, by Mr M. Adam,
A.M. Rector of the Academy.

Meteorological Journal for 1821, kept at Drumel-
zier, in Peeblesshire.

Register of the Barometer, and Thermometer, and
Rain-gauge for 1821, kept at Carbeth, Stirling-
shire.

Meteorological Journal for 1821, kept at Apple-
garth Manse, Dumfriesshire.

Meteorological Journal for 1821, kept at Hillside,
Dumfriesshire.

Meteorological Journal for 1821, kept at Dunkeld
House.

Meteorological Journal for 1821, kept at Colinton
Garden, Mid-Lothian. -

Register of the Thermometer for 1821, kept at

. . Canaan Cottage.

Meteorological Journal for 1821, kept at Inchkeith
Light-house,

Register of the Thermometer for 1821, kept at the
House of Rothiemurchus, Inverness-shire.

Register of the Thermometer for 1821, kept at
Belleville, Inverness-shire.

Register of the Thermometer for 1821, kept at
Delvin Garden, Perthshire.

Register cf the Thermometer for 1821, kept at
Delvin House, Perthshire.

Register of the Thermometer and Weather for1821,
kept at Thirleston, Selkirkshire.

Register of the Thermometer for 1821, kept at St
Andrew’s, Fifeshire.

Register of the Thermometer for 1821, kept at the
Isle of May Light-house, Frith of Forth.

Register of the Thermometer for 1820, kept at
Dundee, Forfarshire.

Register of the Barometer, Thermometer, and
Rain-gauge for 1821, at Castlesemple, Renfrew-
shire.

Register of the Thermometer for 1821, kept at
Fala, Roxburghshire.

Journal of the Barometer, Thermometer, Wind
and Weather for 1820, kept at Kirkwall, Ork-
ney.

DONORS.
Mr Goodwyn.

The American Academy
of Arts and Sciences.

The Most Noble the
Marquis of Huntly.

Mr Adam.

Rey. Mr Somerville.

James Smith, Esq. of
Jordanhill,

Rey. Wm. Dunbar.
Miss Stewart.

His Grace the Duke of
Atholl.
Sir Wm. Forbes, Bart.

Mr Alexander Adie.
Mr John Bonnyman.
J. P. Grant, Esq. M. P.

James Macpherson, Esq.
of Belleville.

Sir Alex. Muir Macken-
zie, Bart.

Sir Alex. Muir Macken-
zie, Bart.

Hon. Captain W. Na-

ier.

Dr Jackson, Professor of
Natural Philosophy.

Mr Alex. Campbell.

Mr John Wilson.

Mr George Steel.

Mr Thomas Scott.

Mr David Paterson.

——

1822.

LIST OF DONATIONS.

PRESENTS.

Register of the Thermometer for 1821, kept at
Blair Castle, Perthshire.

Register of the Thermometer for 1821, kept at
Pladda‘Light-house, Ayrshire. r

Register of the Thermometer for 1821, kept at
High Station Calf of Man Light-house.

Register of the Thermometer for 1821, kept at the
Calf of Man Light-house.

Register of the Thermometer, Winds, and Wea-
ther, for 1821, kept at Greenlaw-house, Kirkeud-
brightshire.

Register of the Thermometer for 1821, kept at the
Garden of Stobo ‘Castle, 610 feet above the level
of the sea.

Register of the Thermometer for 1821, kept at

Stobo Castle, about 770 feet above the level of

the sea.

Register of the Barometer, Thermometer, Rain-
gauge, and Weather, for 1821, kept at Annat-
Garden, Carse of Gowrie, Perthshire.

Register of the Thermometer for 1821, kept at the
Pentland Skerries Light-house.

Register of the Thermometer for 1821, kept at the
Start Point Light-house, Orkney.

Register of the Thermometer for 1821, kept at the
WGnnaird-Head Light-house, Aberdeenshire.

Register of the Thermometer for 1821, kept at the
Bell-Rock Light-house.

Register of the Thermometer for 1821, kept at
Methven Castle, Perthshire.

Register of the Thermometer, and of the Tem-
perature of Springs and the River Tweed, for
1821, kept at Tweedsmuir School, Peeblesshire.

Register of the Thermometer for 1821, kept at
Leadhills, Lanarkshire,

Register of the Thermometer for 1821, kept at
Mount-Annan, Dumfriesshire.

‘Register of the Thermometer for 1821, kept at

Aberlady, East Lothian.

Register of the Thermometer and of Springs for
1821, kept at Hermitage Hill, Leith.

Register of the Barometer and ‘Thermometer for
1821, kept-at Stow, Mid-Lothian.

Register -of the Thermometer for 1821, kept at
Granton, near Edinburgh.

Register of the Thermometer for 1821, kept sat
Eshiells, Peeblesshire.

Register of the Thermometer for 1821, kept at
Isle of Glass Light-house, Isle of Sky..

Register’ of the Thermometer for 1821, kept at
Hopetoun-House, Linlithgowshire. «

3x2

537

DONORS.

His Grace the Duke of
Atholl.

Mr William Souter.

Mr Thomas Dawson.

Mr George Mearns.

Sir Alexander Gordon,
Bart.

Sir James Montgomery,
Bart. M. P.

Sir James Montgomery,
Bart. M. P.

Mr Archibald Gorrie.

Mr Richard Millar.

Mr David Lyall.

Robert Stevenson, Esq.

Robert Stevenson, Esq.

Robert Smyth, Esq. of
Methven.

Mr William Fairlie.

Alexander Irving, Esq.

Lieut.-General Dirom.

Right Hon. the Earl of
Wemyss and March.

Alexander Waddell, Esq.

Rew. John Cormack.

Right Hon. the Lord
President.

Sir John Hay, Bart.

Mr Alexander Reid.

Right Hon. the Earl of
» . Hopetoun.

538

1822.

LIST OF DONATIONS.

PRESENTS.

Register of the Thermometer and Sympiesometer
for 1821, kept at Canonmills, Edinburgh.

Register of the Thermometer for 1821, kept at
Castle-Fraser, Aberdeenshire.

Register of the Thermometer for 1821, kept at
Laurencekirk.

Register of the Thermometer for 1821, kept at
Gordon Castle.

Register of the Thermometer for 1821, kept at
Brechin, Forfarshire.

Register of the Thermometer for 1821, kept at
Penicuik-house, Mid-Lothian.

Register of the Thermometer for 1821, kept at
Kinfauns Castle.

Register of the Thermometer for 1821, kept at
Wick, Caithness.

Register of the Thermometer for 1821, kept at
Dumfries.

Register of the Thermometer for 1821, kept at

Blair-Drummond, Stirlingshire.

Register of the Thermometer for 1821, kept at
Otterburn, Roxburghshire.

Register of the Thermometer for 1821, kept at
Corsewall Point Light-house, Ayrshire.

Register of the Thermometer for 1821, kept at
Lochbroom, Inverness-shire.

Register of the Thermometer for 1821, kept at
Kintyre Light-house.

Register of the Thermometer for 1821, kept at
Sumburgh-Head Light-house, Shetland.

Register of the Thermometer for 1821, kept at
Kaeside, Selkirkshire,

Register of the Thermometer for 1821, kept at
Fleurs, Roxburghshire.

Register of Thermometer and Weather from 1805
to 1816, kept at the Mainsof Dunnotar, Kincar-
dineshire.

Register of the Barometer, Thermometer and Wind,
for 1821, kept at Dumfries.

Register of the Barometer, Thermometer, Winds
and Weather for 1821, kept at Clachnacarry,
near Inverness.

Register of the Barometer, Thermometer, and
Weather, for 1821, kept at Islay-house, Island
of Islay, Argyleshire.

Register of the Barometer, Thermometer, and
Weather for 1821, kept at Lincoln.

Register of the Thermometer and of Springs for
1821, kept at Auchenard, near Mid-Calder.

Register of the Thermometer and of Springs, for
1821, kept at Thurston, East Lothian.

DONORS.

Patrick Neill, Esq.

General Fraser.

Rev. Dr George Cooke.

His Grace the Duke of
Gordon.

Rev. Mr Whitson.

Sir George Clerk, Bart.
M. P.

Right Hon, Lord Gray.

Kenneth Macleay, Esq.

Rev. Dr Duncan.

Henry Home Drum-
mond, Esq. M. P.

Thomas ‘Thomson, Esq.

Mr William Kennedy.

Mr M. Hervey.

Mr D. Loughtson.

Sir Walter Scott, Bart.

His Grace the Duke of
Roxburghe.

Dr William Young of
Fawside.

Mr Andrew May.
Walter F. Campbell, Esq.

of Shawfield, M. P.
The Lincoln Library.
Major Alston.

James Hunter, Esq. of
Thurston.

1828.

Feb. 18.
May 6.

June 3.

17%.
Noy. 18.

Nov. 18.

LIST OF DONATIONS. °

PRESENTS.

Register of the Barometer, Thermometer, and of
Springs, for 1821, kept at Inchbomy, Rox-
burghshire.

‘Transactions of the Society of Arts, vol. 39th.

Specimens of Osseous Breccia, found near Rosia,
in Gibraltar.

Flora Batava, No. 60.

Tracts on Vaults and Bridges, by Mr Samuel
Ware, London, 1822.

Berzelius on the Blowpipe, translated by J. G.
Children, Esq.

Transactions of the Imperial Russian Academy,
relative to the Sclavonian Language, 5 vols.

Memoirs of the Astronomical Society of London,
vol. Ist, part 1st.

Transactions of the Horticultural Society of Lon-
don, vols. Ist, 2d, 3d, and 4th.

Memoirs of the Philosphical Society of Cambridge,
vol. Ist, part 2d.

The Acts of the Parliament of Scotland, vol. 9th.

Memoirs of the Royal Institute of France, Aca-
demy of Inscriptions, vols. 5th and 6th.

Sur. l’Origine'de Cremation, (a translation of Dr
Jamieson’s paper in the Edinburgh Transac-
tions, vol. 8th.)

Introductory Discourse delivered to the Leeds
Philosophical and Literary Society, by C. T-
Turner Thackrah, Esq.

Journal of the Barometer, Thermometer, and
Weather, kept at Faroe, from June 1. 1781 to
September 6. 1782, translated’ from the original
manuscript of Svaboe’s Account of Faroe, vol. 3d,
in the Royal Library of Copenhagen, by W. C.
Trevelyan, Esq. F. R. 5; E.

Register of the Barometer and Weather, copied
from a Journal kept at -Thorshaven, in Faroe,
chiefly by Captain Katen, Commandant in Faroe,
during the years 1795, 6,:7, 8, 9:

Journal of the Barometer, Sympiesometer, and.
Thermometer, kept at Faroe, from June 7. to
October 18. 1821, by W. C. Trevelyan, Esq.

. The Ordnance Map of Middlesex.

Astronomische Natrichten, from No. 15. to 22.
inclusive. :
Series of Specimens of Flints from Warwickshire.

The Population Returns for 1821.

Cleaveland’s Mineralogy and Geology, 2d edition,
2 vols. ¢

Treatise on Optics in the Edinburgh Encyclope-
dia.

539

DONORS.

Mr James Veitch, Inch-
bonny.

The Society of Arts.

Lieutenant Macniven,
26th Regiment.

His Majesty the King of
the Netherlands.

Mr Samuel Ware,

J. G. Children, Esq.

The Imperial Russian
Academy.

The Astronomical So- .
ciety of London.

The Horticultural So-
ciety of London.

The Philosophical So-
ciety of Cambridge.
The. Commissioners* on
the Public Records.
The Institute of France.

Rev. Dr Jamieson.
The Leeds Philosophical
and Literary Society.

W. C. Trevelyan, Esq.

W.C. Trevelyan, Esq.

W. C. Trevelyan, Esq.

Major Colby.

Professor Schumacher.

Edward Grimes, Esq.
R.N.

The House of Commons..

The Author.

Dr Brewster. _

540

1825.

LIST OF DONATIONS.

PRESENTS.

Memoir of Dr Gordon, by Daniel Ellis, Esq.

Description of a new invented Machine for carry-
ing ships into or out of harbours, against wind
and tide, by Jonathan Hull, 1737. .

Register of the Barometer, Thermometer, and Tem-
perature of Springs, kept at the Royal Academy
of Inverness for 1822.

Meteorological Journal, kept at Blair-Drummond,
Stirlingshire, for 1822. r

Register of the Barometer, Thermometer, Rain-

auge, and Temperature of Springs for 1822,
frepe at Huntly Lodge, by Mr A. Murdoch.

Register of the Barometer and Thermometer,
kept at Inchbonny, Roxburghshire, for 1822.

Meteorological Journal, kept at Fala, Roxburgh-
shire, for 1821.

Meteorological Journal, kept at the Island of Glass
Light-house, Isle of Sky, for 1822.

Meteorological Journal for 1822, kept at Loch-
broom, Inverness-shire.

Meteorological Journal, kept at Abbotsford, Rox-
burghshire, for 1822.

. Transactions of the Horticultural Society of Lon-

don, vol. 5th, part 1st.

Memoirs of the Wernerian Natural History So-
ciety, vol. 3d. -

Lettre adressée A la Societé Asiatique de Paris, par
M. Louis De Lor, Paris 1823.

Flora Batava, No. 62.

Register of the Sympiesometer and Thermometer
for 1822, kept at Canonmills, near Edinburgh.
Register of the Thermometer and Temperature of
Springs, for 1822, kept at Thurston, East Lo-
thian.

Meteorological Journal for 1822, kept at Apple-
garth Manse. |

Meteorological Journal for 1822, kept at the Pent-
land Skerries Light-house, Orkney.

Register of the Barometer, Thermometer and
Weather for 1822, kept at Coul, Ross-shire.

Meteorological Journal for 1822, kept at Pladda
Light-house, Arran.

Meteorological Journal for 1822, kept at High Sta-
tion, Calf of Man Light-house.

Meteorological Journal for 1822, kept at the Calf
of Man Low Light-house. [

Meteorological Journal for 1822, kept at Aber-
lady, East Lothian.

Meteorological Journal for 1822, kept at Wick,
in Caithness.

DONORS.

Daniel Ellis, Esq.
Sir Walter Scott, Bart.

Mr M. Adam, A. M.
Rector of the Aca-
demy, Inverness.

Henry Home Drum-
mond, Esq. M. P. :

The Most Noble the
Marquis of Huntly.

Mr James Veitch, Inch-
bonny.

Mr Thomas Scott.
Mr Alexander Reid.

Sir Walter Scott, Bart.

Horticultural Society of
London.

The Wernerian Natural
History Society.

The Author.

His Majesty the King of
the Netherlands.
Patrick Neill, Esq.

James Hunter, Esq. of
Thurston.

Rev. William Dunbar.

Mr Richard Miler.

Sir George Stewart Mac-
kenzie, Bart.

Mr William Souter.

Mr ‘Thomas Dawson.

Mr George Mearns.

Right Hon. the Earl of

Wemyss and March.
Kenneth Macleay, Esq.

LIST OF DONATIONS.

PRESENTS.

Meteorological Journal for 1822, kept at Greenlaw
House, Kireudbrightshire.

Register of the Thermometer and Weather for
1822, kept in Aberdeen.

Meteorological Journal for 1822, kept at Kinfauns
Castle, Perthshire.

Register of the Thermometer and Springs for 1822,
kept at Hermitage Hill, Leith.

Register of the Thermometer for 1822, kept at the _

Garden of Stobo Castle, 610 feet above the level
of the sea.

Register of the Thermometer for 1822, kept at
Stobo Castle, 770 feet above the level of the sea.

Register of the Thermometer for 1822, kept at
Carbeth, Stirlingshire.

Register of the Thermometer for 1822, kept at
Start Pot Light-house.

Register of the Thermometer for 1822, kept at
Kintyre Light-house.

Register of the Thermometer, with the Tempera-
ture of Springs, and of the Tweed, for 1822,
kept at Tweedsmuir in Peeblesshire.

Journal of a Horticultural Tour through some
parts of Flanders, Holland, and the North of
France, by a Deputation of the Caledonian Hor-
ticultural Society.

Asiatic Researches, vol. 14th Calcutta, 1822.

Register of the Thermometer for 1822, kept at
'Thirlestane, Selkirkshire.

. Transactions of the Society of the Antiquaries of
Scotland, vol. 2d, part 2d.

Memoirs of the Wernerian Natural History So-
ciety, vol. 4th, part 1.

END OF VOL. IX.

P. Ne«it, Printer.

541

DONoORs.
Sir Alexander Gordon,

Bart.
Mr George Innes.

Right Hon. Lord Gray.
Alexander Waddel, Esq.

Sir James Montgomery,
Bart. M. P.

Sir James Montgomery,
Bart. M. P.

James Smith, Esq. of
Jordanhill.

Robert Stevenson, Esq.

Robert Stevenson, Esq.

Mr William Fairlie.

Patrick Neill, Esq.

From the Asiatic Society
of Calcutta.
Hon. Capt. Napier, R.N.

The Society of Scottish
Antiquaries,

The Wernerian Natural:
History Society.

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