Natural History Museum Library

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PHILOSOPHICAL

TRANSACTIONS,

GIVING SOME

ACCOUNT

OF THE

Prefent Undertakings, Studies, and Labours,

OF THE

INGENIOUS,

IN MANY

Confiderable Parts of the WORLD.
VOL. LV. For the Year 1765.
LONDON:

Printed for L. Davis and C. R e v m e r s,
Printers to the Royal Society,
againft Gray s- Inn Gate, in Holbourn.

mTdUc.lxvi.

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ADVERTISEMENT.

The Committee appointed by the Royal Society
to diredl the publication of the Philojbphical
Tra?ifa5hons, take this opportunity to acquaint the
public, that it fully appears, as well from the council-
books and journals of the Society, as from repeated
declarations, which have been made in feveral for-
mer ’TranfaShons^ that the printing of them was al-
ways, from time to time, the fingle a6t of the re-
fpedlive Secretaries, till the Forty-feventh Volume.
And this information was thought the more neceflary,
not only as it has been the common opinion, that they
were publilhed by the authority, and under the di-
redlion, of the Society itfelf; but alfo, becaufe feveral
authors, both at home and abroad, have in their writ-
ings called them the PranJaSlions of the Royal Society,
Whereas in truth the Society, as a body, never did
intereft themfelves any further in their publication,
than by occafionally recommending the revival of
them to fome of their fecretaries, when, from the par-
ticular circumftances of their affairs, the 'TranfaSliom
had happened for any length of time to be intermitted.
And this feems principally to have been done with a
view to fatisfy the public, that their ufual meetings
were then continued for the improvement of know-
ledge, and benefit of mankind, the great ends of their
firfi: inftitution by the Royal Charters, and which they
have ever fince Readily purfued.

But the Society being of late years greatly inlarged,
and their communications more numerous, it was
thought advifeable, that a Committee of their Mem-
bers thou Id be appointed to reconfider the papers read
before them, and fele<5t out of them fuch, as they

a 2 Ihould

ADVERTISEMENT.

fhoiild judge moft proper for publication in the future
Tra?jfa6iions ; which was accordingly done upon the
26th of March 1752. And the grounds of their choice
are, and will Continue to be, the importance or fingu-
larity of the fubjedts, or the advantageous manner of
treating them ; without pretending to anfwer for the
certainty of the fadts, or propriety of the reafonings,
contained in the feveral papers fo publiflied, which
muft dill reft on the credit or judgment of their re-
fpedtive authors.

It is likewife neceflary on this occafion to remark,
that it is an eftablifhed rule of the Society, to which
they will always adhere, never to give their opinion,
as a body, upon any fubjedt, either of nature or art,
that comes before them. And therefore the thanks,
which are frequently propofed from the chair, to be
given to the authors of fach papers, as are read at
their accuftomed meetings, or to th« perfons, through
whofe hands they receive them, are to be conftdered
in no other light, than as a matter of civility, in re-
turn for the relpedt ftiewn to the Society by thofe
communications. The like alfo is to be faid with
regard to the feveral projedts, inventions, and curio-
fities of various kinds, which are often exhibited to
the Society ; the authors whereof, or thofe who ex-
'hibit them, frequently take the liberty to report, and
even to certify in the public news-papers, that they
have met with the higheft applaufc and approbation.
And therefore it is hoped, that no regard will here-
after be paid to fuch reports, and public notices ;
which in fome inftances have been too lightly cre-
dited, to the difhonour of the Society.

C O N-

C ON TENTS

T O

VOL. LV.

I. /IN Account of the Pholas Conoides, by J.
^ Parfons, M. D. F. R. S. p. i.

JI. An Account of the Cafe of a young Lady who drank
Sea Water for an Inflam7naiion and Fumour in the
Upper Lip. Communicated by Dr, Lavington of
Taviftock, in Devon, to John Huxham, M. D.
and F.R.S. p. 6.

III. A Letter to the Right Honourable the Earl of

Morton, Prefident oj the Royal Society. Coiitaining
Experiments and Obfervations on the Agreement be-
tween the Specific Gravities of the feveral Metals^
and their Colours when united to Glajs^ as well as
thofe of their other P rgpctrtmts : By Edward Delaval,
F. R. S. M. A. Fellow of Pembroke Hall, Cam-
bridge. p- lO.

IV. An Account of the Cafe of an extraneous Body
forced into the Lungs : By William Martin, Efquire^
of Shadwell. Communicated by Mr. Emanuel
Mendez da Cofta, Librarian oJ the Royal Society.

P- 39-
V. Aji

CONTENTS.

V. An Account of an Earthquake felt at Llfbon,
December 26, 1764: In a Letter to the Rev.
Samuel Chandler, D. D. F. R. S. p. 43.

V J . An Account of the White Negro Jhewn before the
Royal Society : In a Letter to the Right Nonourahle
the Earl' of Morton, Prefident oj the Royal Society ^

from James Parfons, M. D. F. R. S. p. 45.

\"1I. An Account of an Improvement made by Mr.
Peter Dollond in his New Felefcopes : In a Letter
to James Short, M. A. F. R.S. with a Letter of
Mr. Short’s to the Rev. Thomas Birch, D. D.
Secret. R. S. p. 54.

VIII. Some Account of a Salt found on the Pic of
Teneritte, by W. Heberden, M. D. F.R. S. p. 57.

IX. Short and eajy Methods for finding ( i .) Fhe ^puan-
tity of Time contained in any given Number of
Mean Lunations -y (2.) Lhe Number of Mean Lu-
nations contained in any given ^antity of f ime ;
(3.) The Number of Froy Pounds contained in any
given Number of Avcirdupoife Pounds^ and vice
verfa; (4.) Fhe ^lantity and Weight of Water

' contained in a full Pipe of any given Height y and
Diameter of a Bore-y and confequenthy to fnd what
Degree of Power would be required to work a com-
mon Pumpy or any other Hydraulic Engine, when
the Diameter of the Pump- bore, and the Height to
which the Water is to be raifed therein, are given.
Communicated by Mr. James Fergulbn, F. R. S.

p. 61.

X. A Recommendation of Hadley’s S^uadrant Jor fur -

vcyingy efpecially the furveying of Harbours, together
with a particular Application of it in forne Cafes of
Pilotage. By the Rev. John MichelJ, B. D.
F.R. S. p. 70.

XI. An

5

CONTENTS.

XI. An uncommon Anatomical Ohfervaiion addrejjed to
the Royal Society^ by John Baptift Paitoni, Phy~
fician at Venice : Pranjlated from the Italian, p. 79.

XII. An Account of a New Improvement of the Port-

able Barometer. By Edward Spry, M. D. of
Totnefs, Devon: In a Letter to the Right Ho-
nourable James Eatd oj Morton, Prefdent of the
Royal Society. P* ^3*

XIII. A Letter from Mr. Woolcombe, Surgeon at

Plymouth Dock, to Dr. Huxham, F. R. S. con-
cerning the Cafe of a Locked faw. p. 85.

XIV. A Defcription of a beautiful Chinefe Phea-
fant', the Feathers and Drawing oJ which were
fent from Canton to John Fothergill, M. D. F.R. S.

By Mr. George Edwards, F.R. S. p. 88.

XV. A Catalogue of the Fifty Plants from Chelfea

Garden, prefented to the Royal Society by the wor-
fdipful Company of Apothecaries^ for the Tear 1764,
purfuant to the Dirediion of Sir Hans Sloane, Bart.
Med. Reg, et Soc. Reg. aliquando Prcefes : By John
Wilmer, M. D. clarijf. Societatis Pharmaceut .
Lond. Soc. Hort. Chelfean. PrafeSlus et Praledlor
Botanic. P-

XVI. A Courfe of Experiments to afcertain the fpe-

cific Buoyancy of Cork in different Waters : The
refpelHve Weights and Buoyancy of fait Water and
frejh Water : And for determming the exaSi Weight
of human and other Bodies in Fluids. By John
Wilkinfon, M. D. F.R. S. of London a?jd Got-
tingen. p. 95.

XVII. An Account of the Difeafe, called Ergot, in
French, from its fuppofed Caufiy viz. vitiated Rye.
In a Letter Jrom Dr. Tiflbt, of Laufanne, to

George

CONTENTS.

George Baker, M. D. F. R. S. Communicated to
the Rev. Thomas Birch, D. D. Sec. R. S. p. io6.

XVIII. Obfervations for fettlmg the Proportion^ which
the Decreafe of Heat bears to the Height of Situa-
tion. FxtraSied from a Letter of Thomas Heber-
den, M. D. F. R. S. to William Heberden, M. D.
F R. S. p. A 26.

XIX. An Account of a Stone voided without Help
from the Bladder of a Woman at Bury. Communi-
cated by William Heberden, M. D. F, R. S.

p. 128.

XX. ^ Letter from John Bevis, M. D. to the Rev.
Thomas Birch, D. D. Secretary to the Royal So-
ciety i containing Afronojnical Obfervations^ made at
Vienna, by the Rev. Father Jofepli Liefganig.

p. 130.

XXL An Account of the Cafe of a fuppofed Hydrophobia :
In a Letter to the Rev. Thomas Birch, D. D.

• Secretary to the Royal Society, from the Right Ho-
nourable James Earl of Morton, Prefdent of the
Royal Society. p. 139.

XXII. Fwo theorems, by Edward Waring, M. A.
Lucafian Profefor of Mathematics in the Univerjity
of Cambridge, and F. R. S. In a Letter to Charles
Morton, M. D. Sec. R. S. p. 143.

XXIII. A fOifertation on the Nature of Evaporation,
and fever al Phenomena of Air, Water, and boiling
Liquors: In a Letter, to the Rev. Charles Dodgfon,
D. D. F. R. S. From the Rev. tiugh Hamilton,
D. D. F. R. S. Profefor of Natural Philo fop by in
the Univerfity of DuhWn. p. J46.

XXIV. Phyfjcal and Meteorological Obfervations, Con-
jeAures, and Suppoftions. By Benjamin Franklin,
LL. D. and F. R, S. p. 182.

• XXIV. Hifo-

CONTENTS.

XXIV. Hifiorical Memoirs relating to the PraSiice of

Inoculation for the Small Pox, in the Britifli Anie-
rican Provinces, particularly in New England :
Addrejjed to John Huxham, M, D. F. R. S. By,
Benjamin Gale, A.M. p. 193.

XXV. An Account of a Balance of a new Confirublion,

Juppofed to be of life' in the Woollen Manufadiure.
By W. Ludlam, B. D. Fellow of St. John’s Col-
lege, Cambridge. p. 205.

XX Vl. An Experimental Enquiry into the Mineral
Elafic Spirit, or Air contained in Spa Water ; as
well as into the Mephitic ^lalities of this Spirit.
By William Brownrigg, M.D. F. R. S. p. 218.

XXVII. Extradi of a Letter from Mr. Benjamin
Gale, to a Phyfciaii in New England, to John
Huxham, M. D. F. R. S. concerning the fuccefsful
Application of Salt to Wounds made by the Bitmg
of Rattle Snakes-, dated at Killingworth in Con-
ne<flicut, 20 Auguft, 1764. p. 244..

XXVIII. Extradls of three Letters of Sir F. H.
Eyles Stiles, F. R. S. to Daniel W ray, Efquire,
concerning fome new Microfcopes made at Naples,
and their life m viewing the fmallef Objedls. p. 246.

XXIX. An Account of the Sequel of the Cafe of Anne
James, who had taken the Green Hemlock : In a
Letter to the Rev. Thomas Birch, Secretary to the
Royal Society, from Mr. Joliah Colebrooke, F. R. S.

p. 271,.

XXX. Some Account of the Ef'edls of a Storm of

‘Thunder and Lighteming in Pembroke College,. Ox-
ford, 071 June 3, 1765: In a Letter fr 0711 Mr.
Griffith, of the faid College, to the . Rev.. John;
Swinton, B. D. F. R. S. p. 273..

b XXXI. 072r

C O N T E N T S.

XXXI. On the Nature and Formation of Sponges : In
a Letter from John Ellis, Efqutrej F. R. S. to
Dr, Solander, F.R.S. p. 280.

XXXII. RxtraB of a Letter from Dr. John Hope,
Profejfor of Medicine and Botany in the Univerfty
oj Edinburgh, to Dr. Pringle j dated Edinburgh,
24 September, 1765, p. 290.

XXXIII. Memoir^ containing the Hijiory of the
Return of the famous Comet f 1682, with Ohfer-
nations of the fame, made at Paris, at the Marine
Obfervatory, in January, February, March, April,
May, and the Beginning of June, 1759. By Mr.
Meffier, jFironomer, Keeper of the journals. Plans,
and Maps belonging to the Marine of France, Fellow
of the Royal Society in London, and Member of the
Society of Sciences m Holland ; tranfated jrom the
French Matthew Maty, M. D. Sec. R. S. p. 294.

XXXIV. On the Franfit of Venus in 1769, by the
Rev, Mr. Hornfby, F. R. S. and Savilian Projeffor-
f ^ronomy at Oxford, p. ^26.

PHILO-

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PHILOSOPHICAL

T R A N S C T I O N S .

~ » — _ ■ ^ 1 « I .y >, V i I • . i # ,♦ i y I I \ •

I. An Account of the Pholas Conoides, by
J. Parfons, M* D, F. R,

Read Jan. lo, "I" D O myfelf the honor of laying be-
' X* learned Society a fpecies of

Pholas, very little known, and but feldom feen
among the naturalifts', being the firft of them that
has come to my hands. [Vid. Tab. I.]

This Ihell is pivflurcd by RurnphtuSy and called
by the name of Pholas lignorum j in Dutch, Hout^
Mojfely Wood Mufcle, becaufe it is found burrowed
in timber. The fpecimen before you is one of"
infinite numbers that were thus bedded in the keel
of a Spani/h Ihip, which was brought from the
Weft-Indies, a piece of which accompanies the'
fh^ll, to Ihew' how they lie in wood, ftone, or
any other hard bodies, that entertain them. Buf
this name is altogether too vague and uncertain,
unlefs it could be alferted that this is the only kind
that inhabits pieces '-of wood: for every fpecies of
Vol.lv. B Pholas

[ o

Phelas penetrates that and other folid fubftances like-
syife, and fo do various other fhell-fifli. Therefore,
as all fubjedis, in natural hiflory, fhould have fome
precifion in the appellations which diftinguifh them
from each other, the bed: and mod clear method of
giving names to them, is certainly to call them after
lome ftriking character proper to them fpecifically :
and, therefore, I have ventured to give this fpecies
the above title, viz. Pholas ConoideSy being very dif-
ferent in its form, from the oblong, the broad, the
pointed, the cilindrlcal, and every other Pholas I have
feen. And a5 the figure given by Rumphius is fo
imperfedf, and this name fo general, it was neceflary
to give an accurate account, as well as an exaft re-
prel'entation of fo curious a fpecics j and, therefore, I
drew it in four views, and fhall deferibe it as follows :

If we obferve this fpccimen, as it is intire, it will
appear to confift of two great valves, an ante-
riour long piece, a pofteriour long piece, and an or-
bicular detach’d piece at the end of this, at that ex-
tremity which may be called the bafe of the Cone,
Thefe make but five pieces to compleat the whole,
unlefs the white fmooth parts, at the broad ends of
the great valves, are accounted feparate pieces, which
they really are not, but abfolute portions of the
fame valves ; and, as to the circular piece on the
back, it appears to me to be intire, and not divided
into twoj if it may be counted two, then the whole
would confift of fix pieces, according to Monf.
de la Faille's opinion, who feems fond of that num-
ber in the Pholades.

It is an inch and half long, and three quarters of
gn inch thick at the bafe j and this appears to be its

utmoft

C 3 ]

utmoft fize, becaufe the others, which are in this
piece of wood, feem nearly of the fame magni^
tude.

The great valves are of a duflcy white, inclining,-
towards the bafe end, to a purplilh cad: ; where the
Jhice arc very fine and minute, running upwards to-
meet thofe which are larger on the main body, in a
weavy curve diredion j and the fmooth parts of thefe,
as well as the other pieces, are perfectly white, and
without any ftriae at all. The bafe end of this fifli
feems covered with three plates that are white and*
fmooth ; but thefe are only the two fmooth pieces of
the great valves, and the circular pofterior plate,,
mentioned before : and where thefe meet, there are
two depreflions, which terminate in two holes in the
bafes of the great valves, which are half covered by
the pofteriour circular piece. The apex is. round'
and flatidi, and- forms almoft a^ flaarp edge by the
concurrence of the two great valves and the fore
and back edges are united, by the long; pieces fpokeii
of already;

The wood in which they lie was faid to be cedar;
but it rather feems to be of fir, having a fiflile grain.,
like common deal wood, and is as eafily. fplit as that,;,
it is allb extreamly light, and its fibres- are very loofe',,
nor has it the lead Imell like cedar they have the-
fame colour, which is of a yellowifh call; ;, but the-
cedar has- a clofe fmooth graiuj though it is a light
wood, and foft in itlelf : whereas this does not feem;
to be as hard as what we call white deal, which is.
efteemed the lighted and tendered, of ail the clafs of,
firs.

B 2.

The.*

[ 4 ]

The texture of the fhell is very- thin and brittle;
and therefore it is wonderful to 'fee the holes they lie
in fo fmooth and uniform, as if bored with a hard
fharp inftrument. The bafe end is always inward,
and the hole which opens from them outwards very
fmall ; and this is the cafe of every kind which are
thus lodged whether in wood or done j fo that one
muft conclude that they are depofited there in a very
minute date, and not in a date of maturity ; for
then they muft bore their way inwards, and the hole
would be as wide outwards as inwards, and confe-
quently be of equal diameter. But how thefe ani-
mals maintain and increafe the cavity, as they grow
larger, is a queftion which it will be very difficult to
refolve, and has puzzled feveral ingenious naturalifts
in the enquiry.

It is faid they have a power of turning themfelvcs
about wdth a fwift motion, and fo make themfelves
gradual room ; but this will be hard to conceive, if
we confider that a fifh clofely ffiut up within its
valves, and comprefled on all fides, can have no power
of motion. We cannot imagine any animal can move
itlclf, when thus confined, without fome fulcrum
or point of effort, from which to begin fuch motion ;
and if they had fuch tentacula as were capable of
feizing upon the wood, in order to exert themfelves,
there can be no room for it, for it is in clofe contadt
with themfelves in every point. That this is the
cafe, is very clear, from confidering the ftate of toads,
frogs, and other animals, inclofed in blocks of marble,
trunks of trees, &c. which have no communication
with the atmofphere at all. Thefe are foft animals,
and their fhape not at all fit for turning about and
I boring

[5]

boring’ their cavities ; and they are found In moulds
as exactly fitted to their bodies, as thofe are to melted
matter caft into -them by a founder. It may,
however, be fuppofed that the ftone and wood does
actually give way to the growth ol the animal within,
becaufe the fadfs are well attefted ; but how this comes
to pafs,in thefe Pholades and cylindrical Mulcles, and
by what means, toads, &c. can receive aliment 'to
caufe their growth, without any external commu-
nication, mufi: yet remain among thofe fecrets of
nature, which we cannot but admire, without knowing
how they are brought about.

Explanation of 'the Table*.

Fig. I. Is a view of the furface of one of the great
valves, with the edges of the two longi-
tudinal pieces, and with portions of the
fmooth parts at the round extremity or
bafe.

II, Shews the anteriour edge of the Pholas co-

vered by the long fmooth white piece, and,
at the bafe, having part of the fmooth
portions of the great valves in view.

III. Reprefents the pofteriour edge of the Pholas,

with the round white piece upon the bafe
end, and the long ditto, which is larger
than that of the fore edge, running to-
wards the apex.

IV. Is

[6]

IV. Is a view of the bafe extremity, which Is
round like a hemifphere, fhewing the two
holes, one at the end of each great valve,
juft where the procefles of their fmooth
portions, and the edge of the round piece,
meet.

The apices of fome of thefe conoide Pholades are
a little curved ; but that of this fubje(5t defcribed is
ftrait.

We muft: al fb obferve that, befides thefe, there
were great numbers of Cojjiy or worms, in the bot«
tom of the Spanifti fliip ; the veftige of orre or two
of them, if vifible in this piece of wood, and the
channels they make, which are in all diredions, arc
lined with a thin white incruftation, and are of equal
dimenfions all along.

II. An Account of the Cafe of a young Lady
who drank Sea Water for an Inflamma-
tion and Lumour in the Upper Lip, Com-
municated by Dr, Lavington ^Taviftock,
in Devon, to John Huxham, M, D, and
F, R, S,

Read Jan. 17,, \ Young lady of Launcqfton, aged

1765. ftxteen, very tall, of her age,

and of a thin delicate conftitutiqn, very weak and
fickly when a child, enjoyed for fome years paft a
tolerable ftate of health. However being incom-
moded

[73.

moded now and then with an inflammation and
fwelling of the upper lip, which was thought ftru-
mous, was advifed to drink fea water, which fhe ac-
cordingly did every morning, to the quantity of a
pint, for ten days fucceflively ; during which (he
was as well as ufual, till on a fudden ihe was feized
with a profufe difcharge of the catamenia. This
continued fo immoderate and alarming that Dr. La-
vington was confulted. Upon inquiry, he found not
only that the uterine flux was exceflive, but alfo
that file was perpetually fpitting blood from the
gums ; and likewife had innumerable petechial fpots
on her neck and bread; ; and withall a great many
large livid fpots on her arms and legs. Her pulfc
was very quick, though pretty full j her face ex-
ceedingly pale, and fomewhat bloated ; and her flefh
in general was very foft and tender. She was often
taken very faint, but foon recovered tolerable fpirits.

The flux from the uterus at length abated, but
that from the gums increafed to fuch a degree, that
her apothecary took a little blood from her arm.
From the orifice blood ouzed continually for feveral
days, notwithftanding many endeavours were ufed
to {launch it. At lafl: blood iifued from her nofe
perpetually, attended with frequent faintings, in
which fhe at length expired, choaked as it were with
her own blood. But before fhe died, it was very re-
markable, that her right arm was quite mortified
from the elbow to the wrifl : and it is to be further
noted, that though blood, drawn from her fome
weeks before {he began the ufe of the fea water for
an inflammation in her lip, was found fufliciently
denfe, and in a pretty good {late ; yet that drawn off

in

/

[8]

in her laft ficknefs was mere putrid difTolved.

gore.

To this account Dr. Lavington fubjoincd the 'fol-
lowing queries.

Whether or no, a fcorbutic ftate of ‘the animal
juices may not be produced by fait water, as well as
by fait provifions ; efpecially if, as in the prefent
cafe, it doth not pafs of¥ freely by the ufual evacu-
ations, which often happens when drank for a con-
fiderable time, and the body is accuftomed to it ?

Whether the thin tender delicate fibre is not a
morbid difpofition, fomewhat different from the too
vifcid or too lax ? and whether to fuch a conftitution,
attended with a loofe texture of the blood, or a
hedlic habit, a fait water courfe may not be likely
to increafe the acrimony of the blood, rupture the
veffels, and bring on a dangerous hsemorrhage ? And
whether, even to flmmous patients thus circum-
flanced, the Cortex Peruvianus is not more adapted ?

To which Dr. Huxham replied nearly as follows :
“ Jn many cafes I have known very good effedls
“ from a courfe of fea water, when drank in pretty
Jarge quantities, and long continued; but it was
when it purged gently, and now and then puked
“ fomewhat. With the thin, tender, and hedtical, it
feldom agrees. The grofs, heavy, and phlegma-
“ tic, commonly bear it with advantage. I have
“ known it bring on colical pains, diarrhcea, dyfen-
“ tery, and bloody fiools, cough, hedtical heats,

“ wafting of the flefh, and an haemoptoe. It ge-
*' nerally renders the body liable to very great con-
“ ftipation, after it hath been drank for a confiderable
“ time.”

Sea

. .

Sea fait is a kind of neutral fait, that will not pafs
off through the pores of the fkin (except perhaps in
an ammoniacal ftate fome of it may). Its proper
outlets are by ftool and urine. It appears by expe-
riments to be very little alterable by the powers
of the animal oeconomy. If fo, when not duly
difcharged by thefe paffages, in a courfe of drinking
fait water, the marine fait muff be greatly accumu-
lated in the mafs of blood, make it continually more
and more aferimbnious ; and by the mutual attraction
of its particles, when fo abundant, run into molecula
too large to pafs the minuted: veffels, occafion ffag-
nations ; and by irritating thefe capillaries increafe
the impetus a tergo^ and often bring on ruptures of
thofe veffels, extravafations, blotches, fpots ; in a
word, all the fymptoms of the fcurvy in the higheff
degree. Indeed it is very well known, that the
mod: healthy failors cannot long live in drinking mere
fait water for common drink.

VoL. LV.

C

III. A

[ 10 ]

III. A Letter to the Right Honourable the
Earl of Morton, Prfident of the Royal
Society, Containing Experiments and Ob-
fervations on the Agreement between the
Specific Gravities of the fever al Metals^ and
their Colours when united to Glafs^ as well
as thofe of their other Prppad^ions: By
Edward Delaval, F. R, S. M. A, and
Fellow of Pembroke Hall, Cambridge.

My Lord,

Read Jan. 24, T" T A K E the liberty of laying before
>765* Jl^ your Lordlhip the following paper,
containing a variety of fad:s and experiments, which
I have endeavoured to apply to fome Optical in-
quiries.

Befides the experiments originally contrived and
made by myfelf, I have repeated moll of thofe
which I have quoted from others.

Sir Ifaac Newton, in his Optics, has fliewn hy
a feries of experiments, that the feveral differences
of colours, exhibited by thin tranfparent plates, are
occafioned by their feveral thickneffes; and that
therefore the tranfparent parts of bodies do, ac-
cording to their different fizes, refledt rays of one
colour and tranfrnit thofe of another; and confe-
quently that the bignefs of the component parti-
cles of natural bodies may be conjedured from
their colours ; fince the particles of thofe bodies
moft probably exhibit the fame colours as a plate
4 of

of equal thicknefs, provided they have the fame
denfity. He concludes this whole dodtrine in thefe
words : I have hitherto explained the powers of

bodies to refledl and refradt, and (hewed that
“ thin tranfparent plates, fibres, and particles, do,
according to their feveral thickneffes and denfitiesy
“ refledt feveral forts of rays, and thereby appear
“ of feveral colours \ and by confequence, that no-
thing more is requifite, for producing all the
“ colours of natural bodies, than the feveral fisc,es
“ and denfities of their tranfparent particles.”

Though he has accurately fhewn what colours
arife from the feveral changes of thicknefs, I do not
find that any one has attempted to explain in what
7na?mer the differences of denfty, in the component
particles of bodies, contribute to produce the feve-
ral differences of colours: and therefore I thought,
that if inftances could be produced of bodies whofe
feveral differences of colour appear to be propor-
tioned to their feveral degrees of de77fity, it would
tend to illuftrate this part of Optics.

To this purpofe, however, are conducive all thofe
experiments and obfervations, from which Sir
Kaac Newton has inferred that bodies have their
refradiive and refleBive powers nearly praportional
to their denfities ; and that the leaf refrangible rays
require the greatef power to refledt them : which
is deducible froni/ hence, i. that the rays are
refledted at the greatef obliquity of incidence, and
the nsiolet at the leaf, 2. that the niolet is refiedted,
in like circurnftances, at the leaf thicknefs of any
thin plate or bubble, the red at iht greatef thick-
nefs, and the intermediate colours at intermediate

C 2 thickneffes.

[ 12 ]

thicknefles. 3. The fame appears from the table
(p. 206.) in which the thickneffes of air, water,
and glafs, and the colours produced by them are
fet down.

Thefe experiments are applied by him to tranf-
parent bodies and the colours exhibited by them;
but they are equally applicable to permanently
coloured bodies : and it appears from them, that
denfer fubftances ought, by their greater rejiedtive
power, in like circumftances, to refledl the lefs re-
frangible rays, and that fubftances of lefs denjity
Ihould reflect rays proportionably more refrangible,
and thereby appear of feveral colours in the order
of their denfity.

In confirmation of this reafoning, I fliall give
inflances of natural bodies, which differ from each
other in denfty, though circumftanced alike in
other refpeds ; and fhall fhew that they differ in
colour, in the fame order they do in denfity, the
denfefi being red, the next in denfity orange,
yellow, &c.

In fuch an inquiry metallic bodies feem to de-
ferve our frfl and principal attention, as their
fpecific gravities have been afeertained by well
known and repeated experiments. Without enter-
ing into a minute chemical theory of the princi-
ples of metals, it is fufficient to obferve that they
are univerfally allowed to confift of i. an inflam-
mable or fulphureous matter, which is of the fame
kind in all the metals ; 2. of a fixed matter or
calx, which appears in each of the metals to be
fpecifically different in weight, as well as in other
properties.

' 2 Af

[ T3 ]

As the fulphureous matter, in the intire metals,
ads ftrongly on the rays of light, it is neceffary to
calcine, or to divide them into extremely minute
particles, in order to examine feparately the adion
of the calx, or fixed matter, on the rays of light.

In order to examine all the metals in like cir-
cumftances, by reducing them into the fmallefi:
particles, and depriving them of their fulphur as far
as was pradicable, I expofed each of them, united
with a proper quantity of the pureft glafs, without
any additional ingredient, to the greateji degree of
fire they are capable of bearing, without having all
colour whatever dejiroyed.

In this flate it appears, from a variety of experi-
ments and fads, that they adually do, without any
exception, exhibit colours in the order of their
denfities, as follows.

Gold Red.

Lead — — — Orange.

Silver Yellow.

Copper — — Green.

Iron — — — Blue.

GOLD.

[ 14 ]

* >

GOLD.

GOLD, which is the denfeft of all the metals,,
imparts a red colour to glafsy whenever it is divided
into particles fo minute, that it can be intimately
mixed with the ingredients of which the glafs is
made ; and it feems indifferent in what manner it is
reduced to this ftate. Thus

1. From the powder obtained by rubbing gold
with a pumice ftone, ufed by the goldfmiths
in polifhing it, mixed with nitre, borax, and
potafh, a beautiful red glafs is produced [<j].

2. When a fmall quantity of a folution of gold in
aqua regia is evaporated on a glafs plate, with
a gentle heat, that part of the glafs on which it
lay thinned;, is tinged red^ by the entrance of
the particles of gold into it’s furface [/^].

3. Artificial rubies are made by mixing w'nh glafs y
gold diffolved in aqua regia, and afterwards cal-
cined in the furnace [c].

[fl] Sol fine vefte, cap. 8.

Junker, Confpc(5tus Chem. tab. xxxiii. de Auro, p. 852.
Aiirum detritum pumice, feu pulvis auri pumice, quo aurl-
fabri fua opera poliunt et abradunt, commiftus, Gold-Schliff, fi
cum ana nitri, boracis, ct cinerum clavellatorum liquido funda-
tur, praebet vitrum^ inftar optimi opificum encauftici, 7'ubro colore
pellucidum, fubfidentibus paucis auri granulis ; leftante autore
Solis fine vcfte.

Shaw on Boerhaave’s Chem. vol. i. p. 79. Gold ground with
pumice, and afterwards fufed with equal parts of nitre, borax,
and pot afhes, affords a fine tranfparent red glafs.

[^] Philof. Tranf. N°. 286.

[f] Neri’s art of Glafs, chap. i2g.

Calcine Gold with aqua regia many times, pouring the water
upon it five or fix times : then put this powder of Gold in

4. Kunkcl

[■15 3

4. Kunkel prepared a powder for the fame purpofe,
by precipitating the gold from the folution by
an alkaline liquor

5. Gold precipitated by tin from aqua regia, and
melted with glafs in a proper proportion, tinges
it with a beautiful ruby colour : this method
was difcovered by Caflius [^], and farther im-
proved by Kunkel [y'].

6. The fame colour is produced by fufing gold
with a large proportion of tin, and two thirds
of lead, or by mixing it with regulus of anti-
mony, or tin by calcination, and adding to glafs
the powders of gold obtained from thefe pro-
ceffes f^].

7. Gold amalgamated with mercury, and digefted
with it for a conliderable time, may be reduced
to a fubtile powder by expelling the mercury :
this powder, melted into the glafs^ tinges it of a
beautiful red [/6].

earthen pans, to calcine in the furnace, till it becomes a red
powder ; which will be in many days ; then this powder, added
in fuflicient quantity, and by little and little, to fine cryfal glafs^
which has been often call into water, will make the tranfparent
red of a ruhy^ as by experience is found.

[r/J Lewis’s Hiftory of Gold, p. 176.

[^] Caflius de Auro, p. 105.

[/] Junker, Confp. Chem. tab. xxxni. de Auro, p. 861.

[^] Shaw’s Notes on Boerhaave’s Chem. vol. i. p, 78.

[/’J Shaw’s Abridgement of Boyle, vol. i. p. 459.

An induftrious perfon, having united Gold with a parti-
cular quickfilver, kept them in digeftion for fome months ; when
the fire having been immoderately increafed, the fealed glafs
burft with a frightful noife; though the upper parts were blown
ofF and fhattered to pieces, yet the lower efcaped tolerably whole;
and I took notice, with delight, that it was tinged throughout
of a fne and glorious redy hardly to be matched by that of Rubies,

. 8. Gold

[ i6 ]

8. Gold leaf melted into the furface of glafs^ by the
eledhric force, imparts a red colour to it : this
was firft obferved by Dr. Franklyn, and has
been often repeated [/].

There are many other ways of communicating
this colour to glafs by Gold ; and I find no method
by which it can be made to produce any other
colour. If it be mixed in larger maffes, without
being minutely divided, it imparts no colour to the
glafs, but remains in its metallic form.

Grummet attributes this colour to the manga-
nefe, ufed in making fome forts of glafs, the colour
of which he fuppofes revivified by the nitre ufed in
the preparation of the gold : it is neceflary there-
fore to mention, that I have given a red by gold
to feveral glajjesy in the compofition of which
there was no manganefe, and often by gold in the
preparation of which there was 7io nitre.

Several preparations of gold will impart a fine red
to the fritt or materials of which glafs is made, in
a fmall degree of heat ; though not minutely
enough divided, or in too large quantity, to remain
mixed with the glafs, when expofed to a degree of
heat fufficient to vitrify them perfectly.

[/] Franklyn’s Letters on Electricity, p. 65.

LEAD.

[ ^7 J

LEAD.

LEAD, which is the metal whofe denjity is
next in order to that of gold, affords a glafs of the
colour of the Hyacinth, a gem whofe diftinguifhing
character is, that it is red with an admixture of
yellow^ the fame colour which by writers in optics
is called orange,

1 . Lead, kept in fufion for a confiderable time, in
a ftrong crucible and a very violent heat, is re-
duced to a glafs of the colour of that gem

2. Lead reduced to litharge, and melted with one
third or fourth part of it's weight of fand, in a
covered crucible, in a ftrong fire for two or
three hours, unites with the fand into an orange-
coloured glafs like the former [/J.

3.. Glafs of Lead is mentioned by feveral authors,
as a compofition proper, without the addi-
tion of any other ingredient, for imitating the
Hyacinth [wj.

[/^] Flora Saturnizans, chap. ii. Henckel de approprla-
tione, cap. ii. fedt. 4.

[/J Junker, Confpe<El. Chem. tab. xix. p-. 434.

Recipe Lithargyrii partes tres, arenae nitidas partem unam ;
mifta imponantur forti tigillo ; per 3 circiter horas tenuiflime
fundantur, quo fa£to malTam fluentem in calidum mortarium
effunde, et habebis vltrum pcllucidum, Hyasinthini ferme coloris.

[wjj Shaw’s Lectures, p. 299.

Lead melted into glafs with fand Is the foundation of imitat-
ing all the coloured gems : for this glafs itfeJf will referable the
Hyacinth, &.C,

Merret’s Notes to Ncri, chap, 61.

Our author mentions not a Hyacinth from glafs of Lead. Bap.
Porta fupplies you with it, I. vi. c. 7, in thefs words : To make

Vol.lv. d silver.

[ i8 3

S I L V-E R.

YELLOW is' the only colour which fihe?',
the metal next to lead in denfity, can by any prepa-*
ration be made to impart to glafs.

1. Without infilling upon what fome chymifts
affirm, that Jilver, on being calcined and ex-
pofed to a violent fire for a long time, was partly
reduced to z. yellow glafs [«],

2. I have often given that colour^ by moiftening the
furface of the glafs with a folution of Silvery and

^ afterwards making it red hot.

3. If Silver be calcined with fulphur, it readily
- communicates 2. yellow colour to glafs [^?].

a very Hyacinthy and not much differing from the true one, put
lead into earthen pots that are very hard, in a glafs furnace, and
there let it ftand fome days, and thus your lead is turned into
gleifsy and 'imitates the colour of the Hyacinth.

. Nichols’s Hiftory of precious ftones, part i. chap. 7. of the
Hyacinth.

The Hyacinth is a ftone (as faith Boetius and Rulandus)
which is red with a certain yellownefsy or rufefcit in auro ; that is,
it is red\n yellow. Impoftors adulterate it w'ith a kind glafs
Tnade of Lead.

Boetii gemmarum et lapidum hiftoria, 1. ii. c. 31. Adultc-
lium Hyacinthi vix mcretur ; in illius locum aliquando fubftitui-
tur ex plumbo vitruiUy quod a vera gemma pondere et duritic
facile diftinguitur ; mollius enim et gravius vera gemma.

[«] Merret’s Notes on Neri, chap. 82. Claveus faw Silver
calcined two months in a glafs furnace ; the twelfth part of
which became a citron glafs.

[c] Shaw’s Abiidg. of Boyle, vol. i. p. 458. To flicw more
particularly that glafs is porous, wc took fiver calcined by
burning on it in the open air, and laid it upon a piece of
gtafy and placed it with the pigment uppermoft, upon a few

4. Having

[ 19 ]

4« Having carefully purified an ounce of Silver,
I kept it in fufion fome hours, with a finall
quantity of glafs, and found, that the glafs,
when cold, had formed a beautiful yellow enamel
on the furface of the Jilver.

5. Leaffilver laid on red hot glafs tinges \X yellow.

When we meet with authors, who mention a
blue or greenifii colour communicated by filver,
the caufe mufi; have been, that the filver ufed in
fuch procefles was mixed with copper , as it gene-
rally is, when it is not carefully purified \p\. I
have always found, that filver purified by the tefl
retained fo much copper, that, when melted feveral
times with nitre and borax, it imparted 2. green
tinge at the firfl and fecond rnelting, though after-
wards 710 fuch colour was obtainable fiom it.

quick coals to neal a while •, we gave it fuch a he^ as might
make and keep it red hot, without fufion ; and then fufrenng it
to cool by degrees, we found that the glafs had required ss yellow

and almofi golden colour . t i i r c

Shaw’s Abridg. of Boyle, vol. ii. p. 98. I kajned from one of

the chief artificers in painted glafs, that thofe of his trade colour
it yellow with a preparation of a calx of Silver . ^

Kunkel’s Art of glafs, part ii. art. 49. Experiment fhews that
it is from Silver the fineji yellow is obtained. Shaw s Lectures,
p. c?i6. A little Silver tinges glaf yfow. ....

Hook’s Micrographia. obf. 10. of Metalline colours. A third
argument that the particles of metals are tranfparent is, t at
being calcined and melted with glafs, they tinge the glafs with
tranfparent colours. Thus the calx of ftlver tinges the glafs
on which it is annealed with a lovely yellow or gold colour.

r*l Merret’s Notes onNeri, c. 90. Junker, Con.pe£l:. Chem.
tab. XXXIV. p. 889. 901. Shaw’s Abridg. of Boyle, vol. lu

pi ' ■ COPPER.

[ 20 ]

COPPER.

GREEN is the only colour which chopper,,
the metal next to lilver in denjity^ communicates to
ghjsy when melted with it in a fufficient heat,
'Without any additional ingredient: Thus

1. By grinding cryjial glafs in a copper mortar, and
afterwards melting it, it becomes green..

2. Copper calcined per in a furnace [y.].

3,. Copper calcined with fulphur [r], and

4. Scales beaten off from red hot copper plates
mixed with glafs, equally impart a green colour.
to it.

It is indifferent in what manner the copper is
prepared, in order to tinge the glafs green, pro-
vided it be expofed, 'without any other ingredient, tp
a fufficient degree of heat [s]. 1 have frequently pro-
duced a fine green from copper filings unprepared.

^ {q'] Shaw’s Abridg. Boyle, vol.ii'. p. gS’. Though copper
dried per fe affords but a dark and bafely-coloured calx, yet the
glafs-men tinge their glafs green therewith.

Neri, chap. 92. This fort of pnreji glafs will be tinged into
all colours you define : for example, into an emerald with brafs
thrice calcined,, as is done foe ordinary glafs : into a fea greerh
with brafs calcined to rednefs.

[/■] Junker, Confp. Cbem. tab. xix. p. 433. Beryllus ma-
rinae viriditaUs per cuprum cum fulphure calcinatum.,

[s] Kunkel’s Notes on Neri, chap..32. Though with copper
alone one may produce green,^ it is neverthelefs crocus martis dif-
ferently prepared that makes a variety in it.. I-^have- not foui>d
that the different manners of preparing copper have producad
different colours, f have experienced that by calcining copper per
fe, without any addition, I could produce all the elfeds that the
author t.eaches us to bring about by different preparations of that
metaU

lx

[ 21 ]■

If a quantity Jalfs be added in the prepara -•
tion, they will, by attenuating the mixture, and
confequently lejfening its fpecijic gravity^ make the
glafs incline to blue, tbe colour next in order [/] ^
but this happens only when the fire is. moderate for
in a greater degree of heat, the redundant falts, even
thofe of the mofi: fixed nature, are expelled \u\.

It is true.,' that> copper is mentioned by feme-
writers, as an ingredient: in red glafs and enamel i
but the redy which is the colour of the metal not
difiblved or mixed with the glafs, remains only
while the compofition is expofed to fuch a degree
of heat as is too fmall to melt and incorporate it;
for, if it be fufiered to remain in the furnace afew^
minutes ^ after the copper is added, the mafs will
turn green inftead of red [w] : in efied, the pre-
paration of copper recommended on this occafion,
is exadly the lame as. that ufed in tinging glafs
green^

[/] Flora Saturnizans, chap, xu art. 6-.. When a , green,
colour IS to be given to glafs, care muft be taken «<?/ to ufe loo
much fait in the compofition of the glafs-; otherwife the colou? ,
will be blueljh^ and bordering on the colour of the aiguc marine.

Neri, chap. 32. An emerald colour in glafs-.

In making green- you muft obferve that the metal have not :
much fait I with metal -that hath much fait, as cryffcal and rochetta-
have, you cannot make a fair- green, but only a fea green ; for r
the fait confumes the green, and always inclines the colour to a
blue ; wherefore, when you- would make a- fair green, put commons
metal.

Shaw’s Le£lures, p. 2g. Copper precipitated with commart
fait out of aq-ua fortis gives the torquois- colour t© vtdiite glafs;
when melted therewith.

Kunkel’s- Remarks on Merret’s Notes,, p, 299..

f-wj Ncri, chap. 127. This chapter deferibes the method of
JWaking red -gkfsjJ-n the cGmppfuioa- of which copper is ufed ; and

i I.RQN;.

[ 22 ]

IRON.

IRON, being of all metals the moft imperfedt,
is fubjedt by various means, to be calcined or re-
duced to a ruddy crocus, fimilar to the ruft that'
arifes from it’s being corroded by the acid in the
air. In this date, it requires a confiderable degree
of heat to diffolve and incorporate it with glafs ;
till that heat is applied, it retains it’s ruddy colour ;
by increafing the heat, it palTes through the inter-
mediate colours, till it arrives at it’s permanent one,
which is blue: this being effedled in the lame de-
gree of heat in which we liave examined the other
metals, that is, the great eji that the glafs will bear
without lojing all colour whatever.

The green, with which the glafs ufed for bottles
and chemical veffels is tinged, is occafioned by the
iron contained in the vegetable alhes and fand, of
which that glafs is compofed. When the pots, in
which the matter has been kept in fufion, are

Kunkel makes the following remark on it: “ This compofition
“ is very difficult to make \ it is necelTary to feize the moment
“ at which the matter is well tinged red, to take it immediately
“ from the fire ; for half a quarter of an hour too much is luffi--
c;ent to change tf s colour’* In the next chapter, fpeaking of a
red enamel, into the compofition of which copper enters among
other ingredients, Kunkel makes this remaik . T his ccmpo-
fition is very fine, and lefs troublefome than the prcceuiiig one.
“ but, after having added the copper, the matter muft not be left
“ on the fire ; if this is not attended to, it becomes green, and the
“ red colour that it had taken at firlt does not lojL”

Gcllert, Chem. Mctallur. problem 97. Copper gives a blood-
red to glafs; but if it is left too long on the fire, it becomes green,^

nearly

1 23 )

nearly emptied, the glafs remaining’ at the bottom’
is always blue } this is caufed by it’s continuing
longed; expofed to the fire, and in fo fmall a quan-
tity that the fire has a greater efFedt on it. The
whole mafs acquires the fame colour ^ if too much
fand be added in proportion to the afhes ; for, in
that cafe, the materials being more difficult of
fufion, the workmen are obliged to ripply a greater
heat, and to continue it longer.

It is known, from the experiments of Leinery
and others, that the vegetable afhes contain iron [at].
To examine whether that metal be alfo contained
in the fand ufed in making this glafs, and how far
the colour of the glafs depends upon it, I made the
following experiments :

Exp. I. Having procured fome of the fand ufed
in making green glafs, I melted two parts of it
with one part of borax, and one part of nitre, and
found that it produced a glafs fimilar in colour to
that which is made with the fame fand fluxed with
pot afhes. Froni hence it appears, that the colour-
ing matter was contained in the fand.

Exp. 2. I mixed- three parts of this fand with-
one of powder’d charcoal, and expofed it for fome

[x] Becher, Phyf. Subterran. p, 67.

Hsec prima terra (vegetabilis) cum mlneralibus vitris, quae ex
arena et I'llicibus parantur, conveniens eft, ut nulla re, nifi colore,,
inde difcerni queat, qui viridis eft, vel fuhcoeridcus^ indelebilcni
regni fui afterileum lervans, nempe 'vegetahilem v'iriditatc7n ex-
primens.

Flora Sat. cap. 8. Note

As that blue or green colour is owing to the iron which is
found in the afhes ot all vegetables, it muft not be lo.jked on as
a mark capable of charadterifing a vegetable earth.

hours

[ 24 ]

'hours to a red heat. When this mixture was cold,
1 feparated from it, by a magnet, fmall grains of
trorii weighing about one twentieth part of the
fand.

Exp. 3 . I melted fand thus deprived of it's iroti,
v/ith half its weight of borax and the fame quan-
tity of nitre, and found that it produced a per-
feftly colourlefs and tranfparent glafs.

Exp. 4. To two parts of the white fand ufed in
making cryftal glafs, and one of 'borax and nitres
I added a twentieth .part in weight, of the grains
of irony which I had extrafled from the fand by
Exp. 2. and having vitrified this compofition, 1
found that it was become exactly fiinilar in colour y
to that commonly ufed in making green glafs.

Exp. 5. I expofed feveral pieces oi green bottle
glafs made at different glafs-houfes, under a muffle,
to a ftrong 'fire, for the fpace of half an hour, and
found that they were all become blue.

If the crocus of iron is added in too great a pro-
portion, it continues to adhere together, and re-
mains unmixed, or at lead; imperfectly mixed, with
the glafs, retaining for that reafon the colour
natural to it when undifiblved; or if it be in a
fmaller quantity, though yet in too great a pro-
portion to be diffolved, it will make fome inter-
mediate colour between the ruddy and the blucy
which lafi; it always imparts, when iii a fufficient
degree of fire and a proper proportion. The ne-
ceffity of a due proportion of metal to the glafs has
been already infianced in gold, which if in too
large a proportion to be difiblvcd by the glafs, in-

flead

[ 25 ]

ftead of imparting a red colour to it, runs together
in it’^s metallic form.

Henckel has given us a method of making a
beautiful blue glafs by this means. It con fills
merely in mixing iron with the matter of which
the pur eji glafs is compofed, and expofing it to a
violent Jire. Gellert obferved alfo, that iron imparts

to glafs this colour |_y]. Mr. Lehman obtained
the fame colour from emery, which is a kind of
iron ore^ or ferruginous ftone, by mixing it with a
vitrifiable earth ; which colour he attributes to the
iro7i contained in it [2;]. Neri mentions a fky colour

[y'j Henckel, Defect. 6. On a blue obtained from iron.

1 coloured glafs with iron, and gave it a very fine blue. I had
calcined, in a pot, hleings of Styrian fieel, which I kept about a
quarter of an hour in the fire, without fiii ring them, till they had
taken a purple colour, bordering on violet ; I mixed about half
a grain, which I had ground well in a glafs mortar, with fifteen
grains of very white flint and a very fine alkali ; I put the whole
into a crucible, covered it with care, and expofed it to the inoji
violent fire. The furnace being cooled, I found a glafis of the
colour of a fiapphire j it was impoflible to fee a finer blue, cither for
colour or tranfparence.

Gellert. Chem. Metallurg. vol. ii. prob. 97. Cobalt calcined
gives to glafs a very fine blue ; but if too much cobalt, for exam-
ple an eighth part, .is ufed, the glafs’w'ill become black. The
calx of iron produces the fame efifeSi ; and fometimes it happens
that one fide of a thin piece of glafs is of the colour of r/y?, while
the other fide is blue.

[z] Lehman, Treatife on the formation of rhetals, p. 37.

As to the earth of cobalt, or bifmuth, which is the bafis of the
blue colour, Henckel confidered it as a martial earth in his Opufe.
miner, p. 573. Some experiments which I have made render
that opinion very probablei I have obtained a very fine blue
colour from 2l ferruginous Spanijlh emery : having once pulverifed
half a pound thereof and mixed it with an equal part of black
flux, I melted this mixture iaa well-covered crucible in a pretty

VoL. LV. E' imparted

[ 26 ]

imparted to glafs by Bohemian granates, which he
condantly pradlifed at a manufadtory in Flan-
ders [a\. It is well known that it^on is the metal
contained in thofe ftones ; that they obey the load-
ftone [b^ ; and that, being calcined with a proper
heat, they yield a confiderable quantity of iron [c).

I expofed in a crucible to a glafs-houfe fire, for the
fpace of thirty hours, part of a flint glafs retort,
in which a native green vitriol of iron had been
diftilled, and which had been corroded and tinged
by it: by this means it became coloured of a fine

violent fire; when the matter was melted, I flung in an inflam-
mable fubftancc: when that had intirely ceafed burning, I emptied
the crucible, and obtained a mafs of a moji beautiful fapphirine
blue ; but which, as one may imagine, fonn attracted the moifture
of the air ; I repeated the experiment again without putting any
black flux, and the colour became ftill finer; but it was remark-
ably beautiful when the mixture was melted with a vitrifable
earth. I can attribute this colour only to tlie parts of iron con-
tained in the emery.

[a] Neri, chap. 90. A curious perfon and pra£tical chemift
may extra<Sf a wonderful red from gold, from filver a Jky colour,
and a much fairer from granates of Bohemia, which are low
priced ; for, being fmall, you may draw a tindture from them, as
I have often done in Flanders.

Boyle of gems, Shaw’s Abridg. vol. iii. p. 107. Sufpeefting,
for feveral reafons, that {oyc\g. granates contain, befides other metal-
line fubftances, many corpufcles of a ferruginous nature, I made
choice of fome fmall ones, which, by their deep and almoft dark
colour, I guefled to participate largely of and applied
them to a vigorous loadllone, which, as I expedfed, took them
up : and hereto they conftantly adhered till they were forcibly
feparated therefrom — ibid. vol. iii. p. 120. A chalybeate tindlure
obtained from granates.

[f] Junker, tab. x. p. 273. Multi minus pell ucent ;

atque ex his vulgares praeduri, atque alioquin igne indomiti, per
ignem folarem grandibus vitris caufticis colledtum, denique in
fluorem redadli funt, ac merum ferrum praebuere.

tranfparent

[ 27 ]

tranfparent hilled not diftinguilhable from that which
cobalt imparts to glafs.

Iron vitrified per fe is converted into a blue
glafs [d].

In fhort, it is indubitable that iron is the only
metaly which will, without any addition, impart to
the matter of glafs a blue colour for copper will not
communicate that colour, without the addition of
a confiderable quantity of [alts, or fome other mat-
ter that attenuates it j and the other metals cannot
by any means be made to produce it at all.

Having fhewn that the metals exhibit colours,,
invariably in the order of their denfities, when
melted with in a proper proportion, without

any other ingredient, and expofed to a fuficient heat ; ;
I fhall proceed to fliew that the other preparations
of the metals, viz. their folutions, precipitates, ,
cryfials, &c. do for the moll: part exhibit the fame
colours, in the order of their denfities, though not fo
invariably as their glafies ; fome fmall variation of
colour happening in the more imperfect metals,
probably from a change of denfity in their difterent
preparations.

[<3^j Lewis’s Courfe of Chem. p. 49. The fpecific gravity of
iron is to that of gold as 7,645 to 19,640. This metal requires
a great degree of heat to melt it, when it throws out fparkles, lofcs .
confiderabiy of its weight, and is. at length converted into a dark .
t>lue glafs.

El 2 '

GOLD

[ 28 ]

GOLD.

GOLD precipitated from aqua regia, and
wafhed with hot water or boiled in a folution of
alcaline fait, becomes red on being expofed to a
flight heat. Lewis, Hiftory of gold, p. io8.

2. The fame colour is produced when this precipi-
tate of gold is ground with oil of vitriol, or fpirit
of fulphur; or if it be mixed with fulphur, and
the fulphur burnt away. Junker, tab. xxxiii.

P* ^59-

3. The fmoaking fpirit of Libavius, mixed with
gold and afterwards drawn off from it by diftil-
lation, changes it’s colour to a blood red. —
Sol fine vefte, exp. 19. Junker, tab. xxxiii.
p. 861.

4. Gold is reduced into a red powder, by amalga-
mation with mercury, and expoling it for a
conliderable time to a flow heat. — Boyle’s
Abridg. vol. ii. p. 77. Junker, tab. xxxix.
p. 987.

3. if fix parts of antimony are fufed with one of
gold, and the antimony driven off by the blaft,
a red powder of gold is left behind. — Caffius de
Auro, cap. 10.

6. if gold leaf be cemented and ground with decre-
pitated fait, hartfliorn, pumice, or chalk, and
expofed to a proper heat, the metal becomes red,
and may be precipitated from a folution of
thofe fubftances in a red powder. — Junker, tab.
XXXIII. p. 854. Lewis’s Hiftory of gold, p-74.
Sol fine vefte, cap. 6.

7 . A red

[ 29 ]

7* A red tindlure may be prepared from gold by
feveral methods mentioned byLibavius, Alchem.
lib. ii. p. 130. Junker, tab. xxxiii. p. 868.

8. A folution gold in aqua regia prepared from
fal ammoniac may be fublimed of a blood red
colour. The fame is effedled by diffolving the
calx, or crocus of goldy in other menftrua.
Lewis’s Hiftory of gold, p. 100. Junker, tab.
XXXIII. p. 857.

9. A folution of gold in aqua regia, evaporated pro-
perly, affords cryftals of a bright red colour.—
Caflius de Auro, p. 109. Junker, tab. xxxiii.
p. 862. 868. Lewis’s Hiftory of gold, p. 99.

10. Aurum fulmmans moiftened with water, has
been found to tinge gems deeply of a fine red.
Phil. Tranf. N°. 179.

1 1. A folution of gold tinges ivory, cotton, the
fkin, and other fubifances red.

Rubies being frequently found in gold minesy it is
very probable that they receive their colour from
that metal ; and from this circumftance, before the
experiment had been made, Libavius rightly con-’
je(Sured that a folution of gold would communicate
a ruby colour to glafis. Libavii Alch. p. 88.

It does not appear that, excepting the colour
natural to gold in its intire date, any other than’
red can be obtained from preparations of this metal :
it is from this colour, which gold affumes when-
ever its metallic brightnefs is deflroyed, that
writers in chemiftry call it leo ruber \i\.

[e] Libavius de natura inetallorum, lib. i. cap. 4. de auro. "
In iuo manifefto cittinum eft, in occulto fummam continet rul?e-

2 LEAD.

[ 30 ]

LEAD.

THE only coloured preparation of leady is that
produced by calcination in the furnace. The firft
of the primary colours produced by this procefs is
yellow, the calx paffing from that colour through
orange into red.

It is remarkable, that, though in the calcination
previous to the reverberatory heat in which thefe
colours are produced, the lead is diminiJJjed in
weight j yet in the reverberatory fire it gains con-
fiderably, and in proportion to that increafe of
gravity, it paffes from the more refrangible to the
lefs r frangible colours ; fo that while the calx re-
mains of a lefs weight than that of the lead originally,^
it’s colour is yellow, with the next mcreafe of
weight it paifes to orange, which is the colour of

dlnem ; unde et non tantum tin£lum ipfum eft, fed et tin£luram
ruhedlnis confert abundante'm.

Dum c'ltrinum dicitur, externus vultus qualis eft poft excodti-
onem refpicitur : ilia tamen citrinitas igne caementi et in opere
philofophico fumma rubedtne permutatur, Itaquehinc eft philo-
Ibpliorum axioma, quod in dtrinitate lateat rubedo excellemiftinia,_
qualis eft rubedini gemmae.

V oces occultum, manifeftum, non ita pueriliter funt accipiendae,
quafi in fuperficie fit flavum, in centro rubrum: fed progrefliones
colorum in perfedlione artiliciali notantur, quod naturali pro-
cfivitate et difpofuione poft citrinitatem abolitam, alTuinat
rubedinern.

Leo ruber non folet vocari, ante quam ab arte eleboratum, et
aftrale, ut aiunt, fadtum. Potentia tamen etiam fimplcx et natu-
rale aurum ita vdcare non eft abfurdum, cujus tindiura appella,
tur ejus fanguis, quo vocabulo et fcrnienturn denotatur.

glaft

\

;[ 31 ]

glafs of lead ; and when the calx is increafed more
in weight, fo that it’s gravity is become greater
than that of the lead originally^ it paffes into red,
the next colour in order.

Thefe three colours fucceeding each other in
proportion as the gravity of the metal increafes,
, feem to prove that, in this cafe, the greater denfity
produces the lefs refrangible colours : and as orange
is the colour of this calx, when in a middle degree
of weight, between that which is lighter and that
which is heavier than the original metal, it appears
that orange is the colour natural to lead when it’s
weight is neither much increafed nor diminidied.

SILVER.

THE only preparation of fiver, which is of
any primary colour (except the yellow it im-
parts to glafs, and other vitreous fubftances, as
earths or falts) is luna cornea, which Mr. Boyle
fays is of a J air yellow, Shaw’s Boyle, vol. i. p. 255.
Phyfical EjSays, Edinburgh, 1754, vol. i. p.310 [yj.

[y] Art. 10. Remarks on chemical folutions and precipita-
tions, by A. Plummet, M. D.

When either a muria of fea fait, a folution of fait ammoniac,
or fpirit of fea fait (for thefe three have nearly the fame efFedls)
is put into a folution of ftlver \ it becomes milky, and, as it were,
crudled, and at length a white powder fubfides to the bottom :
this powder, being wafhed with warm water and dried, is foftand
impalpable j it’s weight exceeds that of the filver diflolved by

COPPER

[ 32 ]

COPPER and I R O N.

I T appears then that all the preparations of
goldj lead, and fiher, invariably retain the colours
peculiar to the order of their denjities, and that they
are the fame ^uoith thofe njohich they co7nmunicate to
glafs.

The two mod: imperfect metals, copper and
iron, being very ealily adled on by almoft all men-
Itrua, the colours of their folutions, &c. viz. green
and blue, are apt to change into each other’s order;
the copper in lome folvents becoming blue and the
iron green, and in other folvents vice verfa ; this
probably depending on the increafe or diminution
of their denfities.

The folutions of copper, in the acids of nitre and
fea flit, and in the vegetable acids, are green. But
if copper be attenuated, by folution in volatile
alcalies, it becomes blue. Theophraftus and others
have obferved, that emeralds are frequently found in
copper mines ; and it is probable that they obtain
their tinge from that metal.

I melted fome emeralds with twice their weight
of falts, and found that they had formed a fine
geren glafs, fuch as would have been produced from
the fame quantity of a vitrifiable earth, and about
a hundredth part of its weight of copper.

t

more the one fixth part. This powder comes much fooner to
fufion than filver, but does not recover the appearance or pro-
perties of that metal ; for it looks like a piece of yellowijh glafs,
femiopaque and brittle, yet bending or yielding a little, whence
it gets the name of luna cornea.

Iron

[ 33 J

rron diffolved by the vitriolic acid is' green ; bat
if further attenuated by a chemical procefs, it pro-
duces that beautiful colour called 'Prujjiaii blue,
Phil. Tranf. N®. 38. Henckel, Differt. 6.

A fimilar blue may be obtained from the iro7i
contained in the alhes of all plants. Henckel,
Flor, fat. chap. 8. parag. 55.

Having expofed a pound of wood aflies in a luted
crucible, to a pretty Ifrong fire, for thirty hours,
the greatefl part of them became tinged by the
iron contained in them.

A blue may be alfo extradled from a martial
*vitriolj by fpirit of wine. Henckel, de appropria-
tione, chap. 2. parag. 257.

An inftance of a mineral fubflance changing it’s
colour from green to blue on it’s fpecijic gravity
being dhninijhedf appears in a ftone defcribed by
Dr. Grew in the Mufeum of the Royal Society :
this gem is a kind of emerald, which, when expanded.
by heat, becomes blue, and remains of that colour
till cold, in which ftate it returns to it’s ufual
colour, which is green.

Tin is not capable of being vitrified, or impart-'
ing any colour to glafs ; nor are any preparations
of it of any primary colour.

F

VoL. LV. •

MERCURY.

[ 34 ]

MERCURY.

THERE is no body of an intermediate weight
between gold and mercury ; and it is probable that
a great part of the difference between their fpeci-
he gravities depends on the Jhiidity of the one and
the folidity of the other.

Mercury is not capable of communicating any
colour to glafs, being fo volatile that it will not
bear the degree of heat neceffary to incorporate it
with the glafs in fufion.

But it is well known that it’s calx, either pre-
pared per fe, or by diffolving it in an acid and
evaporating the menftruum, is red,

2. A folution of mercury tinges the fkin, 6cc. red,

as gold does.

P L A T I N A.

THE fpeci/ic gravity platinahtingntOivly equal
to that of gold, it feems neceffary to examine whe-
ther the colour of it’s preparations correfpond with
thofe of gold.

On looking into a differtation written by Dr.
Lewis on that metal, in the Philof. Tranf. I find
that the precipitates and cryjials obtained from
folutions of platina are red: and that a folution of
that metal in aqua regia to perfe6t faturation is of a
dark red, though, when diluted, ; in the fame

manner that ‘‘ a red liquor (as Sir Ifaac Newton

obferves) in a conical glafs, looks of a pale and

dilute

[ 35 3

dilute yelloWf at the bottom, where it is thin ;

and a little higher, where it is thicker, orange \
‘“where it is thicker Hill, it becomes red-, and
“ where it is thickeft, the liquor is deepeji and dark-
“ eft." Newton’s Opt. p. i6o.

H AV I N G gone through thefe experiments and
fadts, which feem to {hew that the metals mvzx'vdkAg
exhibit colours in the order of their denfities, when
melted with glajs^ under the circumftances above
mentioned j and that the other preparations of the
fame metals, for the moft part, aftume the fame
colours', it feemed probable that the caufe, on
which the colour of natural bodies depend, may
fometimes be conjedlured from the chemical ana-
lyfis of fuch fubllances. This I have attempted
with regard to the colour of plants.

It is known from the experiments of Lemery
and others, that all earth is impregnated with iron ;
that the ferruginous matter is received into the
roots of plants in their growth, and makes part
of their fubftance, and is univerfally diifeminated
through them j and. that iron may be feparated by
a magnet from the afhes of all vegetables [^].

It has been already obferved, that the green
colour of thc^/<^ ufed in making bottles, is caufed
by the iron contained in the materials of which it
is made ; and I have cited Becher’s opinion, that
the green or blue colour in glafs is an indelible
mark of it’s vegetable origin.

\^g'] Lemery’s Mem. cle I’Academ. anno 1706.

Memoirs of the Acad, of Upfal and Stockholm, of the cafth
found in vegetables, by J.G. Wallerius, 1760.

F 2 This

. [ ,36 ]

This obfervatlon of the conftancy of that cotour
in glafs made of vegetable ajhest and it’s being
caufed by irony led me to conjecture, that the colour
of the intire vegetables arifes alfo from the iron, fo
univerfally diffufed throughout their fubftance in
their growth.

Green is the colour which iron aflumes conftant-
ly, when diilblved by the acid in the airy that metal
thus diffolved being a true green vitriol of iron [/»];
and as this ferruginous or vitriolic matter is univer-
fally difleminated through the leaves and branches
of plants, thofe parts of it which are at the furface
will, by their contaCt with the air, alTume the
colour peculiar to its fait or vitriol.

Mod: vegetables, when they grow in fuch a man-
ner as to be defended from the contaCt of the air,
are prevented from becoming green.

This happens to the roots of trees, and as much
of their flem as is covered with earth ; grafs grow-
ing under ftones, or other bodies, that accidentally
lie bn it, is white \ not having the lead green, but
as the air has accefs to it : and it is a method
commonly ufed by gardeners, to cover with earth
thofe parts of plants which they would preferve
white : by that means hindering them from being
tinged green by the contaCt of the air, as the parts

[/>] Shaw’s Notes to Boerbaave’s Chemiftry, vol. i. p. 94.
Iron is eafily difl'olved in falts, dew, air, &c. By the a£Uon of
any of thefe it contradis a ruff, which js nothing but the flowers
,of iron, or iron difl'olved, and lorfakcn by it’s diilblvent ; for ircn
examined with a microfcope when it full becomes rufly, fhews
it’s furface covered with a number of pellucid vltrieik lamella:,
or glebes, which, being afterwards dried by the fluid menftruum’s
evaporating, become a ruddy caU.

expofed

C 37 3

cxpofed to it are ; though it appears from experi-
ment that the prefence of light, as well as of air, is
neceffary to the produ<fl;ion of the colour of plants.

Befides the iron didblved at the Jurface of plants
by the air, that which is contained in the injide of
them, may be kept in a ftate of folution, when it
meets with a proper quantity of acid', and it is
remarkable that the inlide of moft fruits and other
parts of plants remain green no longer than they
continue in an acid ftate.

The quantity of iron contained in plants will
not appear too fniall to produce their colour, when
it is known that one grain of vitriol, of which only
a fmall part is iron, the reft being acid and water,
is able fenftbly to communicate a green colour to
ten thoufand grains of water. Lemery mentions
this great divifibility of iron as an argument of it’s
being able to pafs into the fmalleft parts of plants.
Mem. Acad, anno 1706.

A circumftance which ftrongly confirms that the
colouring matter of vegetables ^ and a ferruginous
vitriolic fubfance^ are of one and the fame kind, is,
that the vitriol of irony which is greeny palfes
through the fame colours, while it’s moifture is
evaporating, which vegetables do, when by wither-
ing they undergo the fame fort of change : the
vitriol deprived of it’s water by calcination grows
yellow and then red [/j ; and Sir Ifaac Newton

[i] Boerhaave’s Chem. vol, ii. procefs 164. If this fecond
calx (that is, grren vitriol reduced to powder by a moderate heat)
be calcined in a crucible, in aii open rtrong fire, it grows yelloWy
-rtidyAvA at length becomes a deep purple powder.

has

[ 38 ]

has obferved that, when vegetables wither y feme
“ of them turn to a greenifi yelloWy and others to
“ a more perfect or orangey or perhaps to redy

“ pafling firfl through the aforefaid intermediate
“ colours : which changes feem to be effedted by
the exhaling of the moiflure, which may leave
** the tinging corpufcles more denfe and fomething
“ augmented by the accretion of the oily and earthy
‘‘ parts of that moifture.” Newton’s Optics, lib. ii.
prop. 7.

This is the only palTage in Newton, in which he
inftances any permanent colour of a natural body as
arifing from a change of denfity : and though he
has not any where at large delivere'd his opinion
on thisfubjedt; it appears that, in this cafe, he
conlidered the lefs refrangible colours in withered
vegetables as ariling from their increafe of denfity ^
which is what I endeavoured in the beginning
of this paper to prove deducible from his doc-
trines.

I am.

My Lord,

Your Lordlhip’s
moft obedient
and moft humble fervant.

Old Palace Yard,

Jan. 17, 1765.

Edward Delaval.

IV. An

[ 39 ]

IV. Ah Account of the Cafe of an extraneous
Body forced into the htmgs : By William
Martin, Efquire^ of ShadwelL Commu-
nicated by Mr, Emanuel Mendez da
Cofta, Librarian, of the. Royal Society,.

Read Jan. 17, Tuefday 23d October, 1764,

*7 5- about fix in the evening, as one of

my maid fervants was drinking coffee, and eating
toaft and butter, having a child in her lap, who had
like to have fcalded itfelf, and fhe was apprehenfive
would have broke the cup,, being furprized, and at-
tempting to fpeak haftily,. in the very adion of de.-
glutition, unfortunately forced a piece of the crufty
part under the epiglottis, which made its way into
the larynx, or upper part of the wind-pipe ; which,
notwithhanding the many vigorous efforts nature
made (by a violent and inceffant cough) to difchargc
it, yet it fixed like a wedge (as fhe gave me
to underffand) ; and in a few hours fhe was de-
prived of her fenfes and her fpeech, and lay in
great agonies, with violent agitations of body, re^-
fembling ftrong convulfions, fetched her breath very
fhort, and it was expeded Oie would expire that
night. As I was in the houfe when the accident
happened, every method that I could poflibly think
of was made ufe of for her relief, but without effedf ;
and as refpiration was attended with the greatefl dif-
ficulty,

[ 40 ]

ficulty, I ordered about ten ounces of blood to be*
taken from her arm, which feemed in fome meafure
to relieve her breath 5 this was two hours aftei* the
accident. The cough continued about three hours,
’till her ftrength was in a manner quite exhaufted,
and (lie feemed to be intirely fenfelefs, except at in-
tervals, pointing to her bread: ; and whenever I
examined her pulfe, forcibly, and in great agonies
prefiing my hand to the fcrobiculus cordis, or heart
pit, as the feat of her diforder. I left her about
twelve o’clock that night ; and defired my fervants,
who attended her, to call me, if they obferved any
fudden alteration, which they accordingly did about
two in the morning, when 1 was informed Hie was
expiring (as they thought) and indeed, as I foon
haftened to her afhftance, I was of the fame opinion.
However, as I found her fomewhat more fendble,
but in great agonies; and making motions to be
blooded again, as fhe had a full pulfe, and the greateft
difficulty in refpiration, I took away about the fame
quantity as before, which feemed to give her fome
relief, and Are continued much more quiet. At this
time her cough had left her, and I was convinced,
by her complaints, the extraneous body had made its
way into one of the lobes of the lungs. It was with
the greateft difficulty we could get her to fwallow
any liquid, which for fome time threw her into violent
commotions. In this languid ftate flie continued
for feveral days, begging of God to releafe her by
death ; and defiring me to open her body, which I
promifed. But what was very remarkable in this
cafe, notwithftanding the great agonies ffie was in
whilft awake, yet the fecond night after the acci-
dent happened, ffie fell alleep about twelve o’clock
I. (whilft

[ 41 ]

(whilfl; Infenlible) flept found for feveral hours ; and.
whilft in that date of relaxation fetched her breath
quite eafy, as fhe did every night after, when afeep,
with a ferene pulfe, but always waked in exquifite
pain, and in great agitations.

In a few days I obferved her breatli to fmell very
drong, and I made a prognodick, that nature (in
order to expel her enemy) would form an abfcefs or
apodemation in the lungs (as the only chance for her
life) and would bring it up, by the fame channel it
went down ; though 1 was not without apprehen-
fions (as there was a prominence pointing outwards,
and attended with great forenefs) that an empyema
or collection of matter would be formed in the con-
cavity of the bread, which, if it had made its way
outwards, would (in all probability) have proved
fatal. However, on the eleventh day from the ac-
cident, fhe was of a fudden feized in the morning in
bed, with a naufea, violent deknefs, and a cough,
when the impodume in her lungs broke and difeharged
itfelf by the mouth, with a large quantity of bloody
matter, in which the portion of crud was happily
entangled, about the bignefs of a large hazel nut, or
filberd (being rather oblong than round) with a great
quantity of dimy fubdance, in which it was inve-
loped. After which, for an hour or more, fhe
complained of violent pain and forenefs in the whole
cavity of the bread, with great tremors j however
they foon went off, and her fpeech returned imme-
diately, and as perfeCl as before the accident, though
languid ; for, during the major part of her illnefs,
die could exprefs herfelf nootherwife, than by apply-
ing one’s ear clofe to her mouth, and by giving her

VoL. LV. G time,

/

[ 42 ]

time, file could then (by a flow whifper) make us
fenfible of her wants j the extraneous Iwdy prefling,
or in fome meafure obflrudling, the fine threads or
ramifications of the par vagum, or eight pair of
nerves that come out of the brain, and are difperfed
on the larynx, and accompany the bronchi of
the trachea or wind-pipe, even to their minutefl
branches. She is now in a fair way of recovery,
though weak, and afliifted with a dry cough, at-
tended with an uncommon hollow found, as if her
lungs were impaired.

I would beg leave to obferve that the late baron
SuafTo’s lady died by an accident fimilar to this, only
different as to the extraneous body, viz. a cherry-
ffone, which was the caufe of her death. And the fa-
mous Greek poet Anacreon died by the kernel of a
grape, in the fame manner. Another inftance hap-
pened lately to an acquaintance, who was killed by a
piece of chefnut, which went the wrong way, as we
commonly exprefs it. And a gentleman, no long
fince, had the misfortune of fwallowing a quarter of
a guinea, in the fame manner, which killed him.
Nor did I ever of hear any perfon’s recovering in a
cafe of the like nature.

William Martin.

Shadvvell, Nov. 22, 1764,

V. An

[ « ]

V. An Account of an Earthquake felt at
Lifbon, December 26, 1764 : In a Let-
ter to the Rev, Samuel Chandler, D, D.

F, R. S,

Read Jan. 3T, YTTEdnefclay December 26, 1764, I
*'5- VV was awakened about 3 o’clock in
the morning by violent fqualls of wind, and a deluge
of rain, accompanied with almoft uninterrupted
fiafhes of lightning, many of which ended in a
bright purple. About 8, we had fome didant claps
of thunder; at 10, fome more. Before ii,the rain
ceafed, and the fun fhone forth. In Jefs than half
an hour after, we had a fudden diock, preceded by a
rumbling noife, and fucceeded by a dead cairn of at
lead half an hour. Mod of them here maintain,
that it was the fevered diock they have felt ; but as
it laded no longer than you could clap your hands
twice, it did little or no damage. They unani-
moufly declare however, that they never had any
thing of the fame kind, this being a fudden perpen-
dicular heaving up ; whereas all their former diocks
were iindulatory. As it is the only one I have felt,
I can give no decidon ; and I dare fay you will be-
lieve my curiodty will be fatisfied without a fecond
to compare with it. I had folly enough, in the
mean time, to invent a method for meafuring the
drength and diredion of future diocks. Lad night,
they fay, we had a gentle diock about 12 o’clock.

G 2 Thank

more than half a yard deep by the torrent, and the
guds of wind are mod dreadful. We have already
got fome bad accounts from fea.

Take a vedel, making the portion of a fphere of
three or four feet diameter. Place it on a ground-
door. Dud it all over on the indde with a bar-
ber’s puff, and then pour fome water gently into it.
Upon the fmalled tremor, the water will wadi the
dower from the parts of the veffel upon which it
rifes; and will of confequence mark the diretdion
and height of the fhock.

and direSUon o.

\

VI.

[ 45 ]

I

VI. jln Account of the White Negro foew7i
before the Royal Society : In a L,ettcr to the
Right Honourable the Karl of Morton,
P ref dent of the Royal Society ^ fro?n James
Parfons, M. D, F. R. S.

My Lord,

Read Jan. 31, | M H E white boy, who was brought

>7^5- Jl^ before this learned Society on
Thurfday laft, came to me with his mafter on Sun-
day afternoon ; and according, to the defire of your
lordfhip and the gentlemen prefent, I made the ne-
celhary inquiry into the feveral circumftances relative
to his being born of black parents, and find the fol-
lowing notices very fatisfaftory ; to which I have
added fome obfervations which, I hope, will not be
foreign to the fubjedl.

It appears that the father and mother of this boy
were brought down above three hundred miles from
an in-land country to the Gold Coaft in Africa, and
were bought among a great number of others, and
put on board a flaip bound to Virginia j where they
arrived in the year 1755.

They became the property of colonel Benjamin
Chambers, of the Falling Springs, in Cumberland
County, in Pennfilvania; and are now employed upon
an eftate in Virginia, which the colonel pofefTes in
right of his lady, whom he married in that province,

although

[ +6 ]

although he lives with his family in Pennfilvania,
where he fold the boy to his prefent mader ; of
which fatfl, I faw the bill of fale that palled between
the colonel and him.

The father and mother of this child are pcrfeflly
black, and were both very young when landed; the
woman not being above fixteen years old, and her
liulband not more than fix years older ; and when
they landed, being afked, how far flie was gone
with child ? anfwercd, fo as to be underftood to
mean, that Ihe was with child fomething more than
fix moons, and that this was her firft pregnancy.
They alfo declared, that they had never leen a white
pcrlbn before they came to the fhore where Euro-
peans were employed in buying black Haves.

The prefent owner of this boy is Mr. James-Hill-
Clark, whom I informed of what had pafied be-
tween Dr. Franklin and myfelf, on Friday morning
laft on this fubjedf; for I paid him a vifit, and in
the courfe of our conveiTation he informed me, that
while he was in England before, he received a letter
from his lady, in which was fome of the wool of a
white negro child’s head, by way of curiofity ; and
when I mentioned it to Mr. Clark, he alfured me
that this very boy was fhewed in Pennfilvania as a
great rarity ; and that, to his knowledge, the wool
lent in the letter was taken from this child’s head.
He was born about fix or feven weeks after his pa-
rents landed in Virginia, in the year 1755; and was
purchafed by Mr. Hill-Clark of colonel Chambers
in 1764, fo that he appears not to be quite ten years
old ; and his mother has had two children lince,
who are both as black as the parents.

4

/

Now,

[ 47 ]

Now, though this deviation of colour In the
child, from the contrary hue of both parents, is very
fingular, and fomething preternatural, yet in dances
of the fame kind have happened before. We had
one about four years ago here in London, which was
a white girl, fomething younger than this boy, but
exadlly fimilar in colour, wool, &c. and was faid, by
the perfon who made a fliew of her, to have been
the offspring of a black father and mother. I did
not go to fee her ; but I read an advertifement, con-
cerning her, feveral times in the public papers, wherein
fhe was called a white negro girl ; and was informed
by thofe that faw her, that fhe anfwered the defcrip-
tion in the advertifement very truly. She was fhewn
in town for fome months every day.

To this remarkable cafe I diall fubjoln two others,
one of which I faw myfelf, and the other was given
me by a gentleman of undoubted veracity j which,
though they differ in fome circumflances from the
above, yet have fo much relation to each other, as
will prevent their being cenfured as digrelfions from
the fubjedl.

The fird is of a black man who married a white
woman in York feveral years ago 3 of which I had
an account from an eye-witnefs. She foon proved
with child, and in due time brought forth one in-
tirely black, and in every particular of colour and
features refembling the father, without the lead par-
ticipation from the mother. This was looked upon
as a very fingular cafe, becaufe people naturally ex-
pe(fl the iffue of fuch a marriage would be tawny ;
which indeed is the ufual effe(5t produced by the coii-
grefs of black and white perfons.

The

. [ +8 ] .

The fecond cafe was of a black man, fervant to a
gentleman who lived fomewherc in the neighbour-
hood of Grays-Inn. This black man married a
white woman, who lived in the fame family ; and,'
when die proved with child, took a lodging for her
in Grav’s-inn-lane ; when Ihe was at her full time,
the mafler had bufinefs out of town, and took his
man with him, and did not return till ten or twelve
days after this woman was delivered of a girl, which
was as fair a child to look at as any born of white
parents, and her features exactly like the mother’s.
The black at his return was very much didurbed at
the appearance of the child, and fworeit was not his;
but the nurfe who attended the lying-in woman foon
fitisfied him j for the undrelTed the infant, and
fliewed him the right buttock and thigh, which
were as black as the father, and reconciled him im-
mediately to both mother and child. I was informed
of the fadt, and went to the place, where I examined
the child, and found it true ; this was in the fpring
of the year i 747, as my notes fpecify which I took
upon the fpot.

As I was willing to add as much as polhble to the
above account, I took an opportunity of enquiring
about matters of this fort, in a worthy family who
came to live in Red-Lyon-Square not many months
agoj and had lived in Virginia feveral years in a
confpicuous light ; and was informed by the lady
of the family of the two following curious parti-
culars :

About nineteen years ago, in a fmall plantation
near to that of this family, which belonged to a
widow, two of her flaves, both black, were mar-
ried ;

I *

[ 49 ]

lied; and the woman brought forth a white girl,
which this lady faw very often ; and as the circum-
ftances of this cafe were very particular, I lhall make
mention of them here, both for the entertainment
of the Society and to fliew that this is exadly fimi-
lar to the cafe of the boy before us. When the
poor woman was told the child was like the children
of white people, flie was in great dread of her huf-
band, declaring, at the fame time, that die never
had any thing to do with a white man in her life ;
and therefore begged they would keep the place
dark that he might not fee it. When he came to
afk her how (lie did, he wanted to fee the child, and
wondered why the room was (hut up, as it was not
ufual ; the woman’s fears increafed when he had it
brought into the light ; but while he looked at it he
feemed highly pleafed, returned the child, and be-
haved with extraordinary tendernefs. She imagined
he diifembled his refentment till die diould be able
to go about, and that then he would leave her; but in a
few days he faid to her : “You are afraid of me, and
“ therefore keep the room dark, becaufe my child is
“ white ; but I love it the better for that, for my
“ own father was a white man, though my grand-
“ father and grand- mother were as black as you and
“ myfelf ; and although we came from a place where
“ no white people ever were feen, yet there was al-
“ ways a white child in every family that was related
“ to us.” The woman did well, and the child
was diewn about as a curiodty ; and was, about the
age of fifteen, fold to admiral Ward, and brought to
London in order to be fhewed to the Royal Society ;
but, finding that one of the failors had debauched
VoL. LV. H the

[ 50 ]

the girl and given her the pox, he foon put her un-
der the care of a captain returning to America, and
fent her back to her own country.

The other account is, that admiral Franklin had
taken a Spanifh fliip, in war time, and brought her
into Carolina j and, upon fearching, found a pidlure
of a boy who was as beautifully mottled ail over
with black and white fpots as any dog that ever was
feen 5 it is uncertain which was the ground, or
which colour the fpots were of; but this lady fays,
that feveral copies of the picfturc were taken in Ca-
rolina ; and that they faid it was the portrait of a
child born of negro parents upon the Spanifh main ;
the fhip was bound to old Spain ; and this lady does
not doubt but the admiral may have the pidurc in
his cuftody now. If thefe fails are afcertained by
thefe two gentlemen, they will be worth recording
with the prefent fubjeil, which I will take the trou-
ble of enquiring into further.

Thefe deviations of colour are indeed very extra-
ordinary among the African negroes, but they are
not peculiar to them ; fome parts of America have
alfo limilar variations from the common colour of the
inhabitants ; and as I edeem it a great happinefs
when I can contribute to the entertainment of this
learned body, I cannot excufc myfelf from adding
to the above, what Mr. Wafer’s account of the
Idhmus of America gives us upon the like objects in
that country. See page 134 of his Defcription, See,
London, printed for Knapton in Paul’s Church-yard,
in 1699; where, after having deferibed the natural
copper-coloured complexion of the people, he fiys,
‘‘ There is one complexion fo fingular among a fort

“ of

[ 51 3

of people of this country, that I never faw nor
heard of any like them in any part of the world.

“ They are white, and there are of them of both
“ fexes 5 yet there are but few of them in compa-
“ rifon of the copper-coloured, poffibly but one to
“ two or three hundred. They differ from the
other Indians chiefly in refpedl of colour, though
“ not in that only. Their fkins are not of fuch a
“ white, as thofe of fair people among Europeans,
‘‘ with fome tindlure of a blufli or fanguine com-
“ plexion *, yet neither is it like that of our paler peo-
“ pie, but it is rather a milk-white, lighter than
“ the colour of any Europeans, and much like that
of a white horfe.

“ For there is this further remarkable in them,
“ that their bodies are befet all over, more or lefs,
“ with a fine fliort milk-white down ; for they are
“ not fo thick fet with this down, efpecially on the
cheeks and forehead, but that the lldn appears di-
“ flindt from it. Their eye-brows are milk-white
“ alfo, and fo is the hair of their heads, and very
■“ fine withal, about the length of fix or eight inches,
“ and inclining to a curl.

“ They are not fo big as the other Indians; and
“ their eye-lids bend and open in an oblong figure,
“ pointing downwards at the corners, and forming
“ an arch or figure of a crcfcent with the points
downwards. From hence, and from their feeing
“ fo clear as they do in a moon-fhiny night, we
“ ufed to call them moon-eyed. For they fee not
well in the fun, poring in the cleareft day ; their
“ eyes being but weak, and running with water if
i‘ the fun fliine towards them ; fo that in the day-

II 2 “ time

[52]

time they care not to go abroad, unlefs it be a
cloudy dark day. Befidcs, they are a weak people
in comparifon of the others, and not very fit for
hunting, or other laborious exercifes, nor do they
delight in any fuch. But, notwithflanding their
being thus fluggifli and dull in the day-time,
yet, when moon-fliiny nights come, they are all
life and activity, running abroad into the woods,
and fkipping about like wild bucks, and running
as faff by moon-light, even in the gloom and
fhade of the woods, as the other Indians by day,
being as nimble as they, though not fo ftrong and
lufty. The copper-coloured Indians feem not to
refpedt them fo much as thofe of their own com-
plexion, looking on them as fomething monftrous.
They are not a didindl race by themfelves ; but
now and then one is bred of a copper- coloured
father and mother ; and 1 have feen a child of lefs
than a year old of this fort.

Some would be apt to fufpedl they might be the
offspring of fome European father j but befides that
the Europeans come little here, and have little ccm-
merce with the Indian women when they do
come j thefe white people are as different from the
Europeans, in fome refpeds, as from the copper-
coloured Indians in others. And, befides, where an
European lies with an Indian woman, the child is
always a Modefe, or Tawny, as is well known to
all who have been in the W efl-Indies, where there
are Modefas, Mulattoes, &c. of feveral gradations
between the white, and the black or copper-co-
loured, according as the parents are, even to de-
4 “ compounds.

C S3, ]

“ compounds, as a Mulatto-Fina, the child of a Mu-
“ latto man and Moftefa woman, &c.

But neither is the child of a man and woman<
of thefe white Indians white like the parents, but
copper-coloured as their parents were. For fo
“ Lacenta told rne, and gave me this as his conjec-
“ ture how thefe came to be white, that it was
“ through the force of the mother’s imagination
looking on the moon at the time of conception
“ but this I leave others to judge of. He told me
‘‘ withal that they were but fhort-lived.”

N. B. Lacenta was the king of the Indians among
whom Mr. Wafer lived.

If my time would have permitted, I fliould have
madefome remarks upon thefe feveral cafes; butimuft
feize feme other opportunity for this purpofe; and am.

My Lord,

Your Lordfhip’s mofl refpeflful

and moft humble fervant,

J. Parfons**

Wednefday, Jan. 30, 1765.

VI.

%

C5+]

VII. An Account of an Improvement made
by Mr, Peter Dollond in his New 7^-
If copes : In a Letter to James Short,
M, A, F. R, S, with a Letter of Mr,
Short’s to the Rev, Thomas Birch, D, D,
Secret, R, S,

Dear Sir,

Surry-Street, Feb. 7, 1765.

IH AV E fent you, inclofed, a letter which I re-
ceived this morning from Mr. Dollond, concern-
ing an improvement which he has made in Iiis new
telcfcopes. He, fome months ago, fent me a tele-
fcope, in this new way, of 3 i. feet focal length, with
an aperture of 3 ^ inches ; I examined it, and I ap-
proved of itj I have tried it with a magnifying power
of 150 times, and I found the image diftind, bright,
and free from colours.

You may, if you pleafe, lay Mr. Dollond*s letter
before the Royal Society.

I am.

Dear Sir,

Your moft obedient,

and humble fervant,

James Short.

[ 55 ]

S 1 R,

Read Feb. 7,
1765.

I Take the liberty of fending you the
following fliort account of an improve-
ment I have lately made in the compound objedt
glafles of refradting telefcopes.

The diffipation of the rays of light may be per-
fedlly cor reded in objedt glaffes, by combining me-
diums of different refradlive qualities ; and the errors
or aberrations of the fpherical furfaces may be cor-
redted by the contrary refradlions of two lenles, made
of the different mediums; yet as the excefs of re-
fradtion is in the convex lens, and though the fur-
faces of the concave lens may be fo proportioned as
to aberrate exadUy equal to the convex lens, near the
axis i yet as the refradlions of the two lenles are not
equal, the equality of the aberrations cannot be con-
tinued to any great didance from the axis.

In the year 1758, when my father had condrudled
fome objedl glaffes for telefcopes in this manner, viz.
with one convex lens of crown glafs, and one con-
cave lens of white flint glafs ; he attempted to make
fliort objedl glaffes to be ufed with concave e)^ glaffes;
in the fame manner ; but as the field of view, in
ufing a concave eye glafs, depends on the aperture
of the objedl glafs, the limits of the aperture were
found to be too fmall : this led my father to confider
that if the refradtion of the crown glafs (in which
the excefs was) fhould be divided by means of having
two lenfes made of crown glafs inflead of one, the
aberration would thereby be decreafed, and the aper-
tures might then be larger; this was tried with, fuccds
j in

[ S6 ]

in thofe obie£t glafles, when concave eye glafTes were
ui'ed, and thefe have been ever fince made in this
manner: fome trials were likewife made, at the fame
time, to enlarge the apertures of longer objedt glaffes,
where convex eye glaffes were ufed, by the fame
method ; but thefe not fucceeding, in the fame man-
ner, the method of making them with one lens of
crown glafs, and one of white flint glafs, -was con-
tinued.

As I could not fee any good reafon why the me-
thod, which was pradiced with fo much fuccefs,
when concave eye glaffes were ufed, fliould not do
with convex ones ; 1 determined to try fome further
experiments in that way. After a few trials, I found
it might be done; and in a fhort time I finilhed an
objed glafs of 5 feet focal length, with an apperture
of 3 ^ inches, compofed of two convex lenfes of
crown glafs, and one concave of white flint glafs.

Thinking that the apertures might be yet admit-
ted larger ; I attempted to make one of 3 4. feet fo-
cal length, with the fame aperture of 3 4 inches,
which 1 have now completed, and am ready to ffew
the fame to the Royal Society, if defired.

The difficulty of procuring good glafs of fo large
a diameter, and of the thicknefs required, added to
the great exadnefs of the furfaces, in order to cor-
red the aberration in fuch large apertures, has pre-
vented me from attempting to extend them any farther
in that length. I am,

S I R,

Your moft obedient,

and moft humble fervant,

Peter Dollond.

VIII. Some

C 57 ]

VIII. Some Account of a Salt found on the
Pic ^TenerifFe, by W. Heberden, M. D.

F. R. S.

Read Feb. 7, v ]SJ the account of a journey up the Pic
jI. of Teneriffe, by Dr. Thomas Heberden,
printed in the Philofoph. Tranfadions, Vol. XLVII.
N° 57. there is mention made of a fort of fait, as
well as of brimftone, with which fome parts of the
Pic are covered. There is no difficulty in conceiving
how brimflone may be forced up by fubterraneous
hres; and it is no uncommon thing to find it in other
places : but it is not fo eafy to underfiand how a fait
of fo fixed a nature, as this is, ffiould be fublimed
to fuch a height without being cooled and fixed long
before it arrives at the furface of the earth, where no
fenfible heat is perceived. Neither am T able to ex-
plain, how it happens, that a fubftance, fo eafily
melted in water, is not difiblved and wafhed away,
as fafi; as it can be produced, by the dews, and rains,
and melted fnow.

By means of my brother Dr. Thomas Heberden,
I have procured a parcel of this fait collected from
the Pic, a fpecimen of which, together with fome
of the fulphur, is here prefented to the Society ;
both which, though fo very pure, are juft 2,s they
were taken up. My brother informs me, that the
fait is found not far from the verge of the crater, and
that it is called, by the Spanilli inhabitants of the
Vol. LV. I ^ ifland,

C 58 ]

ifland, falitron j which is the name given by them
to falt-petre ; and that it is fold for about five pence
a pound.

It appears to be the natron or nitrum of the anti-
ents, or, as it is fometimes called, the foflil alkali,
which is the bafis of fea-falt: the fame which is

procured from the Spanifii barilla, and from our own
kelp.

The mineral alkali differs from the vegetable in
its ready cryftallizing without any addition of fixed
air, which is neceffary to make the latter take the
form of cryftals * ; and in its not melting in a moift
air ; and on this laft account it is a much more com-
modious ingredient in medicinal powders, than the
vegetable alkali ; as it is not like this apt to run per
deliquium ; but on the contrary, .inftead of attracting
moifture from the air, it is robbed by the air of its
own moifture, fo that its cryftals foon lofe their
tranfparence, and are turned to powder. The natron
liquefies in a very gentle heat : it refembles the vege-
table alkali in tafte and fixednefs, and like that is
ufcd in making foap and glafs ; and they are both ap-
' plicable to moft of the fame purpofes.

Of the cryftals of natron, when very dry, but yet
with fcarce any white powder on them, i oo grains
may be diffolved in 384 gr. of water, when Farhen-
heifs thermometer is at 37. Such cryftals quite dry,
and juft- inclining to grow white, will lofe of
their weight if dried, with a heat fufficient to fcorch
paper.

* See Dr, Black’s experiments in the Edinburgh Eflays,
Vol. II. page a 1 8.

2 ‘‘ The

[ 59 }

“ The vegetable alkali has a ftronger affinity to
« the acid fpirits of vitriol^ nitre, and marine fait,
“ than the foffil j” for

(r) If the common alkali be added to a faturated
folution of Glauber’s fait in water,, the fpirit of vi-
triol will leave the natron-; and uniting itfelf with
the vegetable fixed fait will form vitriolated tartar ;
which being of difficult folution, much of it will
cryfiallize and .fall to the bottom, while the natron,
robbed of the vitriolic acid, remains difiblved toge-
ther with a fmall portion of the vitriolated tartar.

(2) Gr. 1 66 of quadrangular nitre were difiblved
by heat in a folution containing gr. 138 of pearl-
affies. On cooling, there ffiot fome cryftals of com-
mon nitre, the nitrous acid having left the foffil al-
kali, which is the bafe of quadrangular nitre, to join
itfelf with the pearl-aflies.

(3) Gr. 500 of fal-gem, which feemed quite free
from fal catharticus amarus, were difiblved by heat
in a folution of gr. 654 of pearl-affies. There ffiot
a confiderable quantity of fal fylvii mixed with foffil
alkali, which had been expelled by the pearl-affies
from the marine acid.

Thefe experiments were made and communicated
to me by the Hon. Henry Cavendifli.

Befides the properties, which have been mentioned,
the natives of the Canary iflands have found out, that
they can make matches by dipping paper or tow in
a flrong folution of natron, which will then burn,
except that they do not fparkle, almofl; as well as if
they had been dipped in a folution of nitre, though
upon trial no nitre appears to be mixed with it. The
fait of barilla and kelp 1 find, by experience, to have

I 2 this

[ 6o J

this property, but in a lefs degree,' which may be
owing to their not being perfedly free from other
falts.

It may be doubted whether the mineral alkali be
not generated upon the Pic, where it is found, by the- -
litnefs of that fort of earth to attract out of the air
fome of the principles, of which it is made : for there;
is often feen upon walls a faline efflorefcence, which
proves to be this very faltj and fome earth, as that
at the bottom of a lake in Egypt, is faid to produce
it, fo as to make a conftant lupply of a great quan-
tity, which is every year dug up and carried away.
The natron mufl be in great abundance in the air or
earth, as it is the bafe of that fait, which is the
commoneft of all in almoft every part of the world ;
but though it be every where found, when united
to the acid of fea-lalt, yet there are but very few
es, where we have been able to procure it ^

IX. Shcrl

[ 6i 3-

IX. Short and eafy Methods for finding-
(i.) "The §^a?2tity of "Time contained in ary
given Number of Mean Lu?iations ; (2.)
T*he Number of Mean Lunations contained in'
any given §fuantity of Litne ; (3.) Lhe
Niwiber of Iroy Fou?ids contamed in any
give?! Number of Avoirdupoife Pounds^ and
vice verfa ; (4.) Lhe Quantity and Weight
of Water contamed^ in a full Pipe of any
given Height y and Diameter of Bore ; and
coifequently^ to find what Degree of Power
would be required to work a common Pump^
or any other Hydraulic Engine^ when the
Diameter of the Pump-bore^ and the Height
to which the Water is to be raifed therein^ .
are given. Communicated by Mr, James
. Fergufon, F, R, S.

Read Feb. 7> O O M E time ago, jufl: as I was finifli-

^ table for (hewing the quantity
of time contained in any given number of mean lu-
nations within the compafs of 6000 Julian years, in-
tending tliereby to examine how near our prefent
aftronomical tables would (hew the times of fome
antient eclipfes which we have on record, when the
proper equ ations of the folar and lunar motions were
I ‘ taken

[ 62 ]

taken into the account j I was vifited by my friend
William Rivet, Efq; of the Inner Temple, who
faid he wilhed he had come fooner, hecaufe he could
have put me upon a much fliorter method of com-
putation. I defired him to (hew me his method,
which he did mofl; readily and chearfully. “ It was
“ only to reduce the odd hours, minutes, feconds,
“ and thirds, &c. above the integral days of a luna-
tion, into the decimal parts of a day j which niim-
be of days and decimal parts, being nine times
added together, will be equal to the time contained
in nine mean lunations. And from thele, the
“ time contained in any other affigned number may
“ be found, as follows.

A Table fliewingthe quantity of time
contained in any given number of
mean lunations. The mean luna-
tion being 29 days 12b 44' 3" a'"
; or 2q.i;3o<;908<;io8 days.

Lun. Days. Decimals of a Day,

29*530590^5^08
59.061 18170216

3 88.59177255324

4 1 1 8.12236340432

5 '47-65295425540

6 I/7-'^3545'o64*^
7206.71413595756
8:236.24472680864
91265.77531765972

Explanation.

For tens of lunations, remove
the decimal point one place
forward j for hundreds of lu-
nations, two places; for thou-
fands, thiee places ; and fo on,
as in the aiinexed example ;
and then the remaining deci-
mals may be reduced into
hours, minutes, feconds, Sic.
by the common method of re-
ducing decimals to the known
parts of an integer.

Example.

C 6^ ]

« Example.

In 74212 mean lunations. Qu. How many days,
hours, minutes, and feconds ?

Lun.

Days Dccim, of a Day.

70000

2067141.3595756

4000

1 18 122.36340432

200

5906.1 18170216

10

295'3°59'=85io8

59.061 18170216

2

74212

1 2191524.20824034896

Anf, 2191524 days and .20824034896

decimal parts of a day.

And by redudion, 2191 524 days contain 6ooo
Julian years, 24 days, and .20824034896 decimal
parts of a day, contain 4 hours, 59 minutes, 51
feconds, 57 But in pradice, it is fuf-

hcient to take in four or five of the decimal figures.

Having got this hint from Mr. Rivet, I reverfed
it into a way of finding the number of mean luna-
tions contained in any given quantity of time j for
which purpofe I calculated the following table, upon
the above length of a mean lunation j which comes
the neareft to the truth of any length I have yet
found, when carried back from the prefent times
to the recorded times of antient eclipfes, if the proper
equations depending upon the anomalies of the fun
and moon are applyed to the mean times of new and
full moons.

A Table

[ 64 ]

A Table fhewing the number of mean lunations
contained in any given quantity of time.

Y.

, Decimals of a

^ ' Lunation.

1

12.36853003S63

2

24.73706007726

3

37.10559011589

4

49.47412015451

5

61.842650193 14

6

74.21118023176

7

86.57971027039

8

98.94824030Q02,

9

111. 31677034^65

H.

Decimals of a
1 ' Lunaticn,

1

c. 00141096024

2

0.00283193248

3

0.00423289872

4

0.00564386496

s

. 0.C0705483120

9

0.00846579744

7

0.C098707636S

8

0-0 1 128772992

9

0 01269869616

s.

" DecimpU of a
" I.unatinn,

1

3

3

4
!s
6

7

8

9

i,ccooco;oi93
% 000COO7S387
3.0CO001 J75S0
4.000001 56774
5.00000195567
6.00000235161
7.000002743 54
1.00000313548
9,00000352741

D.

j Decimals of a
Lunation,

M.

Decimals of a
Lunation.

Th:

Decimals of a
Lunation.

X

0.033863x897600

X

0.00002351610

1

0.00000000653

2

0.0677263795200

2

0,0000^.70^221 •

2

0.00200001306

3

0.1015895692800

3

0.00097054831

3

0.000COO01959

4

o-i3S4S*759'340o

4

0.0000.9406442

4

0.00000002613

5

0.1603150488000

.5

0.00011758052

.5

G.00000003 266

6

0.203179x385600

6

C.000141C9662

6

0.00000003919

7

0.21704.23283200

7

o.'Coci646i273

7

0.000000,04573

8

0.2709055180800

8

0.00018812883

8

0,00000005226

9

0.3047687078400

9

0,00021164494

9

0,0000^005879

Explanation.

For tens of years, days, hours, minutes, orfeconds,
remove the decimal "point ‘one place forward 5 for
hundreds, two places j for^thoufahds, three places j
and fo on, as in the annexed example, which is the
<converfe of the former one.

/ *“ ^ r - -.‘ff

r*f f

> . . f j . ..

I • : 'li Mi' -r {

Example.

i

[ 65 ]

Example.

In 6000 Julian years, 24 days, 4 hours, 59 mi-
nutes, 52 feconds, How many mean luna-
tions ?

Years

6000

Days j

^ 20
* 4

Hours

... “
4

Minutes ■

> 50

1 9

Seconds -

r 50

1. ^

Lun. Dec. of a L.
7421 1.18023 176

0.677263795

0.135452759

0.005643865

0.001 175805

0.00021 1645

0.000019596

0.000000784

Anfwcr

74212.000000009

This (hort method may be ufeful in many other
cafes ; but, as yet, I have only applied it to two.
The firft of which is, to find the number of troy
pounds contained in any given number of avoirdupoife
pounds, and the reverfe. The fecond is to find the
quantity and weight of water that would fill an up^
right pipe of any given diameter and height : and
confequently, to know what power would be required
to work a common pump, or any other hydraulic
engine, when the diameter of the bore of the pump,
and the height to which the water is to be raifed,
are given j proper allowance being made for fridfion.
Thefe two cafes are as follows.

VoL. LV.

K

[ 66 ]

^roy weight compared with avoirdupoife weight.

One troy pound contains 5760 grains j and
One avoirdupoife pound contains 7000 grains.
Therefore,

175 troy pounds are equal to 144 avoird. pounds \ and
175 troy ounces are equal to 192 avoird. ounces.

On thefe principles, the tu^o following Tables are

conftru(5ted.

I. A Table fhewing the
number of avoirdup. pounds
contained in any given num-
ber of troy pounds.

2. A Table Slewing the
number of troy pounds con-
tained in any given number
of avoirdupoife pounds.

Troy Avoirdupoife pounds and Je-
Pounds cimah of a pound.

Avoir. -Troy pounds and decimals of a
Pounds pound.

1

2

3

4

5

6

1

8

9

0,822857142857143
1.6457142857 14286
2.468571428571429
3.291428571428572
4.114285714285715
4,937142857142857
5 . 7&0000C00000000
6.582857142857143
7.4057 T42857 14286

1

2

3

4

5

6

7

8

9

1.215277777777778

2-430555555555556

-3-645833333333333

4.861 1 1 1 1 1 1 1 1 1 1 1 1
6.076388888888889
7.291666666666667
8.506944444444444
9.722222222222222
10.937500C00000OCO

Explanation.

For tens of pounds, remove the decimal point one
place forward ; for hundreds of pounds, two places ;
tor thoufands, three places j and fo on, as in the
following examples.

Example

i 67 1

Example i.

In 175 troy pounds, How many avoirdupoifc

pounds?

Troy

Avoirdupoife

100

82.2857142857143

70

57.6000000000000

5

4.1 142857142857

175

144.000000000000

Anfwer, 144,

Example 2.’

In 144 avoirdupolfe pounds, %. How many troy

pounds ?

Av.

Troy

100

i2t.5277777777778

40

48.61 II mill III

4

4.8611111111111

144

175.C000000000000

Anfwer, 175.

When any fignificant decimal figures remain in
the fum, after integral pounds, they are eafily re-
duced into the known parts of a pound : feeing
that, in troy weight, 24 grains make one penny-
weight, 20 penny-weights make an ounce, and 12

K 2 ounces

[ 68 ]

ounces make a pound. And, in avolrdupolfe weight,
1 6 drams make an ounce, and i6 ounces make a
pound.

A Table by which the quantity and weight of water
in a cylindrical pipe of any given diameter and.
perpendicular height may be found.

Diameter of the cylindrical bore one inch.

Feet Quan, of water
high, in cubic inches.

Weight in troy
ounces.

In avoirdupoife
ounces-

1

2

3

4

5

6

7

%

9

9,4247781
1 8,8495562
28.2743343
37.6991124
47. 1 228QOS
56.5486686

65-9734467

75.3982248

84.8230029

4.9712340
9.9424680
14.9137020
19.8849360
24.856170Q
29.8274040
34.7986380
39.7698720
44.741 1060

5-454^539

10.9013078

16.3624617

21.8166156

27.2707695

32.7249234

38-1790773

43-633231-2

49.0873851

Explanation,

For tens of feet high, remove the decimal point
one place forward j for hundreds of feet, tv/o places ,
for thoufands of feet, three places, and fo on : and
you will have the quantity and weight of water in
the cylindrical pipe, fuppofing its diameter to bs
one inch.

The contents of cylinders of equal heights are to
one another as the fquares of their diameters. There-
fore, having found the quantity and weight of vva^
ter in a cylinder of one inch bore, you may find the
fame for any other larger bore, by multiplying the
above-found quantities by the fquitre of the diameter

[ ^9 ]

of the given bore, taken in inches. Thus, fiippofe*
the given bore was lo inches in diameter (the fquare
of which is loo) and the height of water in the pipe
of lo inches bore was 85 feet, The quantity
and weight of the water ?,

F.high.

Cubic inches.

Troy ounces.

Avoird. ounces.

80

753.982248

397.698720

43(>.3323i2.

5

47 123890

24.856170

27.270769

85

801 .106138

422.554890

493.603081

Mult, by

100

100

100

Anfw.

80110.613800

42255.489000

46360.308100

Which number (801 10.6) of cubic inches being
divided by 231, gives 346.8 for the number of v/ine
gallons i and the refpedfive w'eights (42255.489 troy
ounces, and 46360.308 avoirdupoife ounces) being
divided, the frit by 12, and the laft by 16, give
3-521.29 for the number of troy pounds, and 2897.513
tor the number of avoirdupoife pounds. And fo
much would be required to balance this quantity of’
water in a pump, or any other hydraulic engine,
and as much more to raife it as would be fufficient
to overcome the fridtion of the engine.

The realbn for removing the decimal points one -
place forward for tens, two places for hundreds, &cc.
is- evident : for, when any number confids of integer
and decimal figures, tlie fetting of the decimal point
one place forward is the fame thing as multiplying
the number by lO; two places forward, the fame
as multiplying the number by 100 j and fo on : as-
tlie tables, tbemfelves are calculated only from.-,

i to 9.

[ 70 ]

I to 9. But I multiplied by 10 produces 10, and
9 multiplied by 10 produces 90, And lo on for all
the intermediate units.

X. A Reco7?tmendation of Hadley’s Quadrant
for furveymg^ efpectally the furveymg of
Harbours^ together with a particular Ap-
plication of it m fome Cafes of Pilotage,
Py the Rev. John Michel), B. D. F. R. S.

Read Feb. 14, T
1765.

H E ufe of Hadley’s quadrant, as
' an inftrument to take altitudes at

fea, is already fo well eftablifhed, that it wants no
farther recommendation but there are feveral other
purpofes, to which it may be applied, with great
advantage, which, though obvious enough, feem
yet to be hardly fufficiently attended to. There is
no inftrument fo well adapted to many kinds of fur-
veying, cither for exadnefs or conveniency, and par-
ticularly the laft; but the furvcying of harbours, or
fuch fands, as lie v/ithin fight of land, may often-
times be performed by it, not only with vaflly more
eafe, but alfo with a much greater degree of preci-
fion, than can be hoped for by any other means, as
it is the only inlfrument in ufe, in which neither the
exadnefs of the obfervations, nor the eafe with
which they may be taken, are fenfibly affeded by the
motion of a veffel : and hence a fingle obferver, in a
boat, may generally determine thefituation of anyplace

he

[ 71 ]

he pleafes, with a fufficient degree of accuracy, if,
with this inftrument, he takes the angles fabtended-
by two or three pairs of objedls properly chofen uporii
the (hores round about him ; but it will be ftill bet-
ter to have two obfervers, one of whom, being in a
boat, muft, at the time he takes the angle fubtended
by fome two objedls upon the ihore, make a fignal to
the other obferver, who, being placed at one of the
objedls, as a flation, muft at the fame time obfervethe
angle fubtended by the boat and the other objedt.
By this means, two angles in a plain triangle being
given, together with the diftance between the two>
objedts, as a bafe, the whole triangle, and the fitu-
ation of every part of it, will be given likewife.
By fuch obfervations, as thefe, provided the boat be
at red: during the time of making them, and they
be made carefully, with good quadrants, though
without the afiidance of telefcopic fights, the fitua-
rion of places may be eafily determined to twenty or
thirty feet upon every three or four miles.

Befides the ufe of Hadley’s quadrant in furveying,
it may upon fome occafions be very ad vantage on fly
employed in piloting fliips into harbours, the great
readincfs, with which it may be ufed, making it a
very convenient inftrument for this purpofe : but that
this may be done to the greatefl advantage, it will
be necefiary to have a proper provifion made for it
upon the charts, by exprefiing upon them the angles
fubtended by given objedts, by means of which, to-
gether with the bearings, a flilp may be enabled to
know her fituation with areat exadlnefs. The well-

O

known property of the circle, that angles in the
fame fegment are equal to each other, may be often-
times

. 72 ] -

times very conveniently applied upon this occafion j
for if, through any two given objects, we defcribe fe-
veral fegments of circles, in which thofe objeds (hall
fubtend the angles of * 120°, 90°, 8c°, yo", &c.
refpedively, we fhall then know immediately, upon
finding the two objeds fubtend any one of thefe
angles, that we are fmiated fomewhere in the cir-
cumference of the correfponding fegment ; and, the
bearing alfo from one of the objeds being known,
our precife fituation will be determined with great
accuracy.

The manner of deferibing thefe fegments, through
two given points, may be performed in the following
manner. Let B and C [Tab. II. fig. i.] be the given
points : then, joining thefe two points, bifed the
line B C in A, and draw the indefinite right line
DE, perpendicular to B C, through the point of bi-
fedion. Upon BC, at the point C conftitul'e the
angles DCB, F C B, G C B, H C B, &c. refpec-
tively equal to the difference between the angles,
which correfpond to the feveral intended fegments
and 90'’; and on the oppo-fite or fame fide of the
line C B with thofe fegments, accordingly as they
exceed or fall diort of 90°. Then will the points
D, F, G, FI, &c. where the lines CD, C F, C G,
C H, &c. interfed the line D E, be the centres of

* The number and frequency of thefe fegments, as well as
the magnitude of their , rel'peftive angles, muft be determined,
according to the particular circumflances of the occafion, upon
which they are appli^^d : I have mentioned no greater angle,
than 120°, as there are few cafes, in which this v.nll not be
fiifficicnt ; and indeed it is the greateft, that Hadley’s quadrant,
tile only inflrument fit for this purpofc, will eafily admit, accord-
ing to the prefent conftruiSlion of it.

I the

[ 73 ] .

the intended fegments j but, if the angle, corre-*
fponding to the intended fegment, is to be neither
greater or lefs than 90°, the point A, which bifects
the line B C, will be the centre of the intended
fegment.

Thus, if I would have the angle in the intended
fegment, to confift of 120'', 1 conftitute upon
B C, at the point C, the angle D C B equal to
30°, the difference between 120° and 90°, and on
the oppofite fide of C B from its correfponding
fegment, becaufe it exceeds 90°, Then with the
centre D, and radius D C, I defcribe the fegment
C 120 B, in every part of which the two points
C and B will fubtend an angle of 120°.

In like manner, if I would have the angle in the
intended fegment to conlifl of 80°, I conftitute upon
B C, at the point C, the angle BCG equal to 10°,
the difference between 80° and 90"", and becaufe the
intended angle is now lefs than 90°, I place G on
the fame fide of B C with its correfponding feg-
ment. Then with the centre G, and radius G C,
I defcribe the fegment C 80 B, in every part of
which the two points C and B will fubtend an angle
of 80®.

Laftly, if I would have the angle, in the intended
fegment, to confifl of 90°, with the centre A and
radius A C, I defcribe the femicircle C 90 B, in
every part of which the two points C and B will
fubtend an angle of 90°

* If we want a fegment, the angle in which is to be the half
of one we have got before, the centre is already found to our
hands j for it will be the point of interfedlion of the former
fegment with the perpendicular line DE. Thus the point,

VoL. LV. L The

[ 7+ ] -

The demonftratlon of all. this is fo well known to
every geometrician, that it needs not to be inferred ;
but it may not perhaps be amifs to exemplify what I
mean, by applying to it a particular cafe.

The prefent inconvenient and indeed dangerous
htuation of the two lights at the mouth of the
Humber, commonly called the Spurn Lights, mull
probably foon make it necelTary to remove them ;
for the ground, upon which they formerly flood, is
now fo far wafhed away, as not to leave fuflicient
room to eredl them at a proper diflance from each
other ; and frefh ground being grown up to the
fouthward, fo as to make the point above a mile di-
jflant from them, fliips are frequently thereby liable
to be deceived. Jn cafe therefore thefe lights fliould,
at any time hereafter, be removed nearer to the point,
I think the foregoing principle might be very con-
veniently and advantageoufly applied, fo as to enable
entire flrangers to enter the Humber, with the greatefl

where the fegment, correfponcHng to 120", iiiterfefts the liixe
DE, will be the centre of the fegment correfponding to 60°:
the point, where the fegment correfponding to 80°, interfedfs
the line D E, will be the centre of the fegment correfponding
to 40°, &c.

There is another method of finding the centres of thefe feg-
ments, which, if great cxadlnefs is required, will perhaps be
found preferable, in practice, to the former, efpecially in the
larger fegments. The method, I mean, is to fet them off by a
fcale, in which cafe the diftance of the feveral centres, from the
point A, muft be refpc(ffively proportional to the co-tangents of
the angles in their correfponding fegments, or, what is the lame
thing, refpedlively proportional to the tangents of the angles
D C A, F C A, GCA, H C A, ^^c. confiituted upon the line
AC, at the point C; for, making A C the radiu-, the lines
D A, F A, G A, H A, &c. arc the rcfpe<Stivc tangents of thofc
feveral angles,

fecurity,

[75],

fecurity, even in the darken nights, provided oidy
they could fee the lights: and this is the more mate-
rial, as, in dangerous weather, it is frequently the bed
and mod fecure retreat between the Thames and the
Tyne ; but the difficulty of entering it, for want of
proper helps, oftentimes obliges (hips to keep the fea,
not without great difficulty and hazard, when they
might lie here in perfect fafety.

1 have endeavoured to g.ive fome idea of the ap-
plication, I propofe, in the annexed chart, [Fig. 2 ]
which is meant only as a rough draught of the ge-
neral defign, and not as an accurate delineation of
what mud depend upon a future furvey, whenever
the new lights diall be eredled.

The drong black line is intended to reprefent the
high water mark : the fpace included within this,
and which is infcrlbed Spurn Point, as well as that
inferibed Kilnfea Common, is ground, which the
fea never overflows; but all the fpace between thefe,
where the Angle line only is continued, is frequently
waflied over by the fea, the land being there reduced,
at the time of high water, to a meer bank of only a
few yards wide.

The dotted line furrounding the drong black line
reprefents the low water mark ; and the other fpaces
included within dotted lines, and inferibed Trinity
fand, the bull, crofs ridges and broken ground, and
done banks, are fuppofed to reprefent four fands, the
two former lying within, and the two latter without
the mouth of the Humber.

Through the two points B and C, reprefenting the
fuppofed new lights, are deferibed, according to the
rule above laid down, two feries of feginents, one

L 2 feries

[ 76 ]

ferles to the fouth weft, and the other to the north
eaft of them j but, the north eaftern feries lying
tov/ards the land fide, a few of the inner fegments
might be omitted as being unneceftary.

From the point C are drawn lines in the diredlioii
of fixteen of the points of the compafs ; every other
point being omitted in order to make the chart more
diftindl; for no greater nicety is in general wanted,
than what thefe will afford j near the extremities
however of two of the fands, where it may perhaps
be more neceffary, I have added a fhort line to mark
the intermediate point.

I fhall now endeavour to illuftrate the whole bv
an imaginary ftiip’s courfe. Let us fuppofe then a
ftiip to enter the fpace, reprefen ted upon the chart,
from the north, and finding the light C to bear nearly
fouth weft, and the two lights to fubtend an angle
■^of about 5°, fhe will know herfelf to be fomewhere
about the place D, a little lefs eafternly, than the
point of the fand denominated crofs ridges and broken
ground, and at the diftance of about two miles and
a quarter from it, as may appear by the fcale; fhe
muft therefore fteer fomewhat to the eaftward of the
fouth, and, having run about three quarters of a mile, -
fhe will find the light C to bear weft fouth weft, and
the two lights to fubtend an angle of exactly 5°, being
now in the interfedion of the courfe, delineated upon
the chart, with the fegment fo marked ; but not be-
ing yet far enough to the eaftward, ftie muft ftill con-
tinue the fame diredion, till, having run near three
quarters of a mile farther, fhe will find the two lights
fubtending an angle of no more than 4"", and the light
C lying a little to the fouth ward of the weft. From

hence

C 77 ]

hence (he may know herfelf to be at the place E,
fomewhat more to the eaftward, than the fand flae
wants to avoid, and at the diftance of almoft a mile
from it. She may now therefore fafely change her
courfe, and fland due fouth, till having brought the
light C to bear weft by north ftae is right over-againft
the extremity of the fand, at the diftance of about
three or four hundred yards. If ftie ftill keeps the
fame courfe about three hundred yards farther, the
lights will then fubtend an angle of only 2° 30', when
fhe will be fo far to the fouth, as to be clear of all
danger, though flie fhould from thenceforward fteer
due weft; but, for greater fecurity, we will fuppofe her
ftill continuing to ftretch away a little more to the
fouthward, by fleering fouth weft for about a quar-
ter of a mile farther. From hence then fhe may keep
near due weft, wnth which courfe the two lights, in
a run of a mile and a quarter, or a little more, will
both be brought to bear north weft, and be feen to-
gether. In a run of about half a mile more, they
will be again open on the contrary fide from the
former to about 3°, from which they will open to 10°,
in a paftiige of near half a mile farther, when the
fhip will be arrived at the place G, the light C bear-
ing then due north. The change of the angle being
now very great in a very fmall diftance, it will be
very eafy to keep the ftiip with great exadnefs to
whatever part of the channel we pleafe. Let us how-
ever fuppofe, that we mean to keep her in the courfe
laid down in the chart ; from G then we muft fteer
north weft a little weft, and in a run of about a mile,
we fhall firft increafe the angle of the two lights, till
it is fomewhat more than 20”, the light C tlien bear-

C 78 j

ing north eafl:, and afterwards diminifli it again to
about when the light C will bear due eaft.
Having now got far enough within the Spurn, vve
may run due north about a mile and half, firfi; bring-
ing the two lights to bear in one line due fouth ealf,
and then opening them again, on the oppofite fide,
to an angle of about i'’ 30' or 2”, according to our
diftance within the Spurn*; but here, knowing per-
fectly well where we are, we can come to an anchor
in a fafe road, at fuch a diftance from the Trinity
fand as we pleafe, which diftance may be regulated
without difficulty by the foundings, as at the place I,
where the anchorage is very good in five fathom
water,

* In the cafe of a fliip’s being placed nearly In the line of the
two lights, the method of finding onr diftance from them by
their bearing, and the angle they fubtcnc), will fail us ; but, as
it may fometimes be convenient to have the means of forming a
tolerable guefs about our exadf fituation in this cafe, as well as
others, I muft obferve that a pretty good judgment may be made
concerning it, by running a little way in a direction nearly at
right angles to the line of the lights ; for by this means, the di-
ftance run being known, it will appear, from the change of the
angle, under which they are feen, how far they are from us.
Thus, for example, if from the place I, a vdfel fhould run
about a quarter of a mile along the dotted line 1 K, and find,
that this made a change in the angle fubtended by the two lights
of a very little more than a degree, fhe would know herfelf to
be ajmoft two miles from the light C, as would appear by mca-
furing the diftance 1 C upon the fcale.

XI. An

[ 79 ]

XL An uncommon Anatomical Ohfervation
addrejjed to the Royal Society^ by John
Baptift Paitoni, Phyjician at Venice :
Tranjlated from the Italian.

Y duty as phyficlan to the ma-
giftrate of health obliging me to
be prefent at the opening of the bodies of thofe who
die fuddenly, in order to examine into the hidden
caufes of their deaths, gives me frequent opportuni-
ties of obferving remarkable and lingular ph^enome-
na j one of thefe, which (amongft many others) I
remarked in the courfe of the prefent year at the
dilTeilion of a young woman, I do myfelf the honor
of communicating to this Society; nor do I doubt its
being received with indulgence by them, when I con-
lider that the Royal Society was inflituted for the
moft laudable end of the improvement of arts and
fciences, and that of rendering them feviceable to
mankind. As the Pbilofophical Tranfadions are fuf-
ficient proofs of this, I cannot but believe that an
uncommon anatomical ohfervation mull be accepta-
bfe to them.

The fubjed of this ohfervation was a woman of
about 25, of a fwarthy complexion, who had from
her infancy been fubjed to a troublefome convuhive
cough, and fhortnefs of breath upon any extraordinary
exercile ; notwithftanding which, (he was to all out-
ward appearances of a hale and (Irong conffitution,
having a regular and plentiful difcharge of her men-

ftruaj

Read Feb. 14,
1765.

[ 8o ]

ftrua, which ufed to relieve her a few days from her
diforder. At the above age, after having been fiiig-
ing and dancing with her friends in the Carnival time,
being taken luddenly with a cough more violent than
ufual, and a Ihortnefs of breath, die dropped into
the arms of one of her acquaintance, and vomiting
at the fame time a little ferous and frothy liquor, died
immediately.

The body being opened the next morning in the
prefenceof fomeof the college of phyficians,the vifcera
of the lower cavity were firfl examined and found
quite found j the ftomach only was a little extended,
owing to what the deceafed had eaten a few moments
before her death ; but the caufe of her death was
found in the thorax, the right lobe of her lungs be-
ing wanting, as will appear by the following de-
fcription.

The external membrane, which ought to cover the
right lobe of the lungs, was of a livid colour, and
adhered to the pleura. This membrane being cut
through, inftead of the true lobe, there was found
in its place a membranous bag of a milky colour,
without any vifible outlet, and much of the fame
fize as that part of the lungs which was wanting.
This bag being opened, there came out into the
thorax a ferous fluid, void of fmell, which being
Ipread upon the table was found, as to figure, colour,
and fubftance, much to refemble a cuttle filh ; nor
do I doubt but fome whimfical naturalifls, who make
it their bufinefs to furprife the common people, by
the relation of miraculous events, would have de-
clared that they faw part of the lungs changed into a
cuttle flfli.

It

[ 8i ]

It being evident from this, that there was in the
thorax of this young woman a receptacle of ferofity
(if I may fo call it) contiguous to the found lobe, it
will not appear ftrange that, from the violent agita-
tion caufed by the Tinging and dancing, the bag burft,
and that the found lobe, which alone ufed to perform
the office of breathing, being hindered, by the ferous
matter which came out, from exerting its influence, a
fuffocation enfued. The caufes of her habitual dif-
order are equally obvious. In a perfe(5l flate of health
there fhould be two lobes, which together receive the
blood from the right flde of the heart, and tranfmit
it to the left, reducing it in this journey, by their
joint a(5lion, to a ftate of perfection. One of the
lobes therefore being wanting, the other muft have en-
dured confiderable pain in receiving the whole quan-
tity of blood from the heart, and whenever violent ex-
ercife made a quicker circulation neceffary, the blood
mufl: have been flopped, and hence arofe the afore-
mentioned ffiortnefs of breath. Nor is it lefs clear
how the cough came to be fo frequently troublefome,
the motion of the fluids being difturbed, and the de-
licate fibres of the trachea perpetually irritated by
this defeCl. And this is the true reafon why her
menflrua being very plentiful were for fom.e time
very benefleial to her, by caiffing a great diminution
of blood, and leaving a cjuantity of fluids in the veins
more proportioned to the canals of a Angle lobe.

Thefe things, from the difleCtion of the body, are
evident enough, but it ftill muA feem wonderful to
have found a young woman without one of the lobes,
that bag of ferous matter containing nothing in it which

VoL. LV. M could

[ 82 ]

could deferve the name of even the moft imperfedl
one. I know very well that the lungs are fubjedt
to many defedlsj and that there are often found in
them tumours, calloufnefTes, adhefions, ftones, ulcers,
worms, tubercles, waftings, and the like j but none
of thefe caufes could hardly have made the fame
vifcus lofe every fign of its former ftate. The young
woman being deficient in this lobe, it is furprifing
how the other can have performed its office in main-
taining life, and have appeared upon examination
of the common and natural fize, and its veffels not
at all dilated by the quantity of blood which they
received. And as nature has made nothing in vain,
we cannot but'be aftoniffied to find that fingle which
ought to be double, as if a man was to have one kid-
ney inftead of twoj much more wonderful is it
that, in fo delicate and important an adtion as refpi-
ration is, one lobe only of the ufual fize and flrudlure
fhould have performed the fundtions of both. I
know very well that thofe, whofe misfortune it has
been to have part of their lungs only flightly difor-
dered, mufi: have the other confiderably affedted j but
befides that there may have been occafionally relief
given, they cannot for a long time have fupported the
want of a lobe, without giving vilible figns of fo great
a defedl. In this cafe we have reafon to believe that
this young woman was born with this monflrous de-
ticiencyj what is ftrange is, that (he ffiould have
come to her full growth with it, and have been ap-
parently healthy, except the convulfive coughs and
ihortnefs of breath. Thefe are phaDnomena, which
might be accounted for from obftrudbions in the lower

cavity 5

]

cavity; at leafl:, the brown yellowlfh tinge of the face,
is a common iymptom in thefe obftrudions ; but in
this cafe it appears to have been owing to the want
of one of the pulmonary lobes, the other not being
alone fufiicient to work the blood, and give it the
necelTary rednefs.

Short and imperfefl as this relation Is, I hope,
neverthelefs, that it will prove fufficient to convince
the Royal Society of the great regard, which I, with
juftice, have for fo ufeful and praife-worthy an in-
ftitution.

XII. An Account of a New Improvement of
the Portable Barometer. By Edward Spry,
M. D. of Totnefs, Devon. In a Letter
to the Right Hoi^ourable James Earl of
Morton, P ref dent of the Royal 'Society^

My Lord,

Read Feb. 28,r-j^ H I S barometer of my invention,

conftrudion, I prefume, will
anfwer every intention of the ufual, and more com-
plex portable one, and in a much more fimple
and durable manner, viz. The double round at the
bottom makes it dijEHcult (even if we endeavour
thereto) to caufe an afcent of air, or a fall of mer-
cury into the bowl ; which, if the latter circumflance
were to attend it, the quickfilver, from the bowl's
conflrudion, muft remain therein, thence of no in-

M 2 conve-

[ 84 3

convenience. The fmall bowl at the top, with beads
therein, render it far lefs liable to break by the mer-
cury’s afcent, the bowl giving it an immediate ex-
panfe from the colon, and the beads counteradling its
force as fo many fprings, which has fuch an effedl,
that from many experiments (purpofely made) I have
found it no eafy matter to break it by the mercury’s
afcent, which is very eafy in the common one j yea,
it even frequently breaks, if the greateft caution is
not taken in turning it. Its fo well vacuated by
boiling the quickfilver in the tube, that I depend on
its being luminous after being carried fo far ; and, as a
further proof, 1 doubt not of your finding the eleva-
tion above any other. The tube may be as large as
you pleafe j but, if fo, it lliould not be continued
further than the tube’s curve, which Hiould have its
colon fmall (no inconvenince to the infirument, wh.ich
may otherwife take air) by the tube’s being drawn fo,
or, what is better, one of the fmallefi: bore being
joined thereto^

This barometer may be conveniently carried, in-
verted, in a walking- flick, with a fcale contained in
a large tube covering the other, which I fliould have
completed, had I had a fit tube.

The beads, at a certain time, may be apt to detain
a little mercury in the bowl j but that is to be eafily re-
united by fhaking it, or caufing it to re-afeend there-
in. The infirument might have been fomewdial
neater, had 1 (inflead of turning it at the lamp with a
blow-pipe) rendered the tube flexible over a charcoal
fire, and turned it on a flick of pipe-maker’s clay,,
but I could not procure it.

Caution

. t

Caution is requifite, that the beads, in fealing the
bowl at top, do not adhere thereto, being thereby
very liable to break in boiling, or after ; likewife the
rounds fliould not touch one the other, being liable
therefrom to the fame inconvenience. I have made
fome with three rounds, but find them not better than
with two. ^

A diagonal one may be confirudted in the fame
manner, thence capable of being, removed from,
place to place. I am,

My Lord,

Your Lordflaip’s,

And the learned Society’s,

Very humble and obliged fervant,

\

E. Spry.

XIII. Letter fro?nMr. Woollcombe, Sur-
geon at Plymouth Dock, to Dr. Huxham,
F. R. S. concernmg the Cafe of a Locked
jaw.

Read March 7, A Ccording to youT defire, r have
'5- yoo the cafe of the locked

jaw I lately had under my care. ,On Saturday June 2-,
in the afternoon, I was fent for to a poor woman,
who an hour or two before had been taken with an
I opprefiioH .

f 3 .

oppreflion at her breaft, attended with a flight pain
in her fide, and at the fame time complained of a
forenefs in her jaws, and a little difficulty in fvval-
lowing ; as I then took it to be only a common cold,
fhe had fourteen ounces of blood drawn off, and fome
nitrous medicines fent her. Upon vilitihg her the
next morning, I found her relieved as to her breaft and
fide, but her jaw was fixed, and almoff clofed, with
a very great difficulty of fwallowing. Upon a further
enquiry, and fhoit reflexions, I was foon convinced,
file had, that terrible fymptom, a locked jaw. As
this diforder is more frequently the confequence of ex-
ternal injuries than from internal caufes, I enquired
whether fhe had any kind of wound, or cut ; and
was told, that about eight days before a rufly nail
had run into the bottom of her foot j and though the
wound was painful for two or three days, yet it was
cured by their own applications, and had been well
four days before flie was taken with the above com-
plaints.

I therefore examined the foot, and found it quite
whole, though upon prefling the tendons of the foot
file expreffed a little uneafinefs, I now endeavoured
to relieve this terrible malady ; as the blood drawn the
preceding day, was of a firm texture, and her pulfe
full and tenfe, I took away fourteen ounces, which
proved fizy j and having procured fome flools, gave
her an anodyne of forty drops of T.Thebaica, in a very
fmall vehicle, which fhe fwallowed with great diffi-
culty. I then applied a large blifler to her back, but
without any relief. Soon after fhe was feized with
frequent convulfions, which for the time deprived her
of her fenfes j and tho’ in the intervals they were quite

perfect,

[87]

perfed, and her jaw not quite fo fliut, but a little
might be put into her mouth by a teafpoon ; yet fo
great were the fpafms, that fhe never after could fwal-
lowing any thing; and in this manner fhe continued,
with fhort remiffion of the fpafms, till two o’clock
the next day, Monday 4^’% when death put an end
to her mifery. I have been fince told, that an hour
before fhe died, flie could open her jaw, at which
fhe feemed to be greatly rejoiced ; but it was of a
fhort duration, the convulfions again returning, and
a univerfal one carried her oft.

Give me leave to make an obfervation on the cafe,
which I fubmit to year better judgment. That a
locked jaw fhould often be the confequence of an ex-
ternal wound, is nothing new, feveral cafes having
happened that put it beyond doubt; but that fym-
ptoms fhould come on after a flight contufed wound
that had been cured for four or five days ; and make
fucharapid progrefs, as to carry off the patient, in little
more than forty-eight hours after the firfl appearance
of the fymptoms, is very remarkable. We are certainly
much in the dark, in regard to the nervous fyflem ;
but I think it a flrong prefumption, that from the
firft impreflion of the nail, the nerves were fo pecu-
liarly affedted, that, though the irritation was not fuf-
ficient to hinder the external wound from healing, yet
it might be fufficient to difpofe them to fuffer thofe
violent agitations, which ended fo fatally.

On the other hand, is there any reafon to con-
clude, that it was from an inward affedion of the
nervous fyflem ; the wound being well,, and the
woman able to walk about and manage her family
matters ?

If

[ 88 ]

If the above cafe is worthy of your mature re-
flexions, it will be a great fatisfadion to,

S 1 R,

Your mofl humble fervant,

Tho. Woollcombe.

XIV. A Defrciption of a beautiful Chinefe
P Leaf ant ; the Feathers and Drawing of
which were fe?tt jf'om Canton to John
Fothergill, M. D. F. R. S, By Mr,
George Edwards, F, R. S,

Read March 7,
1765.

HE Argus is a fpecies of the
pheafant, the largeft of that genus
yet known, being equal in fize to a full-grown tur-
key-cock, from one of the mofl; northern provinces
of China. I take it to be a male bird, by the beauty-
ful red ikin ou the fore- part of the head, and its fine
blue changeable crefi: and neck j the females of all
the different fpecies of pheafants yet difcovered having
little or no gaudy colours about their heads.

The beak is made like that of our pheafant, of a
yellowilli-white colour : the fore-part of the head,
and the begining of the throat, is covered with a fine
icarlet fkin, feeminglyyoid of feathers, but is 'rough
with a kind of grain. The irides of the eyes are
orange-coloured, more yellow next the pppil, and

redder

^bUos-Trtms.yb'LJ^V. I'AU.Ml.^.ss

I

^/ifAUGirS orIjV£]!f. ,%i^Ae^ .

J- ^{^nJt Jtfi.ttS^ .

i

9

C 8g 1

redder in their outer circumference j the fkin round
the eye is dufky, ar black : it hath alfo blackifh marks
proceeding from the corners of the mouth ; the top
and hinder part of the head and neck are of a fine
blue changeable colour : it has a creft of long loofe
feathers, which I fuppofe it can raife or lower at
pleafure: the lower part of the neck, the back, and
covert feathers of the wings^ are covered with black
or dufky feathers, having a fmall broken tranfverfe
mixture of reddifh brown : the wings> when clofed,
meafure about feventeen inches, though the prime
quill fall fhort of the length of thofe above them :
the wing hath about twenty quills, the outermoft
.ihorteff, which gradually lengthens to the fifth ; the
nine outermoft quills are of a lightifti yellow brown,
fpotted with dufky fpots, of the fize of tares, except
on their inner webs, next the (hafts, where they are
of a dufky brown, with white fpots as fmall as mu-
ftard feeds ; the fhafts of thefe feathers are of a lead
colour ; the eleven remaining quills, which charac-
terize this bird, are of a darker brown than the fore-
going, marked with round and longifti duflcy fpots
on both the inner and outer webs. What is moft ex-
traordinary in thefe feathers is, that each of them has
on the outer web, clofe adjoining to the fhaft, a row
of very diftindl fpots like eyes, fo fliaded as to appear
imbofted : they are larger and fmaller as the feathers
are to the outer quills they are from twelve to fifteen
on each feather j the largeft eyes are an inch in a di-
meter, they are incircled firft with black, and with-
out that with light brown, their fliafts are white j
the eyes in the two or three innermoft quills are not
fo regularly marked, they lofe their roundnefs, and
Vol.lv* N become

[ 90 ]

become confufed j thefe beautiful eyes are not feen,
unlefs the wings are a little fpread j the fingle fea-
ther, of half the natural length, figured in the plate
[fee Tab. III.] will give an idea of the eyes and fpots
beyond defcription ^ the inner coverts of the wings
are brown with black fpots j the under fides of the
quills are marked like the upper, but fainter coloured,
the inner webs edged with light afii colour, which
forms a whitifli bed within fide of the wing. The
throat, bread, rump, and covert feathers, on the
upper fide of the tail, are of a dull orange colour,
with round dulky fpots i the tail hath fourteen feathers
of very unequal lengths, the mlddlemod being each
of them three feet long, the next, on each fide, 1 8
inches, which gradually fhorten to the outermoft on
each fide, which are each 1 2 inches, their colour is
dufky, with a tindture of bright brown, the outer
feathers are dotted with white as fmall as muftard
feeds ; the next within thefe have larger fpots, lefs re-
gularly formed ^ the two long middle feathers have
round white fpots, furrounded with black, on their
outer webs, and larger irregular brown fpots, fur-
rounded with dufky on their inner webs, which are
alh coloured •, the lower belly, and covert feathers
beneath the tail, are dufky with a confufed mixture
of brown 5 the legs and feet are like thofe of turkeys,
with three toes forward, and one backward; the legs,
feet, and claws, are of a greenilh afh colour; the
head and legs of this bird, both in my figure and
defcription were fupplied from the curious drawing
that was fent from China, with the bird’s fkin, which
had neither head nor feet adhering to it.

XV. A

I 91 ]

XV. A Catalogue of the Fifty Plants from
Chelfea Garden, prefented to the Royal
Society by the worjhipfd Company of Apo-
thecaries^ for the Tear 1 764, purfuant to the
DireEiion of Sir Hans Sloane, Bart, Med,
Reg, et Soc, Reg, aliquando Prcefes : By
John Wilmer, M. D, clariff. Societatis
Pharmaceut, Lond. Soc, Hort, Chelfean.
PrcefeSlus et PrceleSlor Botanic.

Read March
1764.

•4. I2101 A Chillea folils bipinnatis
xjL ^bbpilofis, laciniis lineari-
auriculis decuffatis. Linn.

bus, dentati
Sp. plant. 1267.

2102 Achillea foliis fetaceis dentatis, denticulis fub-
integris fubulatis reflexis. Hort. Cliff. 412.
21.03 Amaranthus glomeribus triandris pentandriif-
que, foliis ovatis obtufiflimis emarginatis ru~
gofis. Linn. Sp. plant. 1403.

2104 Anaftatica foliis obtufis, fpicis axillaribus bre*

villimis, filiculis ungulatis fpinofis. Linn.
Sp. plant. 895,

2105 Antirrhinum foliis lanceolatis fparfis, inferlori-

bus oppofitis, nedtariis fubulatis, floribus fub-
feffilibus. Hort. Cliff. 498.
j,io5 Aflragalus caulefcens procumbens, legu minibus
contortuplicatis villofis, Linn. Sp. plant.
1068.

N 2

2107

[,92],

2 1 07 Bidens foliis trifidis quinatifque ferratls petiola-

tis, pedunculis longiflimis.

2108 Borago foliis ramiticationum oppodtis amplexi-

caulibus, calycinis folioiis 4gittatis. Linn.
Sp. plant. 197.

2109 Bupleurum frutefcens, foliis obovatis integerri-

mis. Linn. Sp. plant. 343.

2110 Carica foliorum lobis fmuatis. Hort. Cliff.

461.

21 1 1 Caffia foliis odtojugis ovato-oblongis aequallbus,

glandula bafeos petiolorum. Hort. Cliff

21 12 Chryfanthemum Indicum foliis fimplicibus ova-

tis fmuatis angulatis ferratis acutis. Linn.
Sp. plant. 1253.

2113 Ciftus (iLgyptiacus) herbaceus eredtus ftipula-

tus foliis linear! lanceolatis petiolatis, calycibus
inflatis corolla majoribus. Linn. Sp. plant.

742-

2114 Cleome floribus gynandris, foliis quinatis, caule

inermi. Linn. Sp. plant. 938.

2115 Corchorus capfulis linearibus compreflis, foliis

lanceolatis jequaliter ferratis. Linn. Sp.
plant. 746.

2116 Coris (Monfpelienfis). Linn. Hort. Cliff. 68.

2117 Coronilla fruticofa, foliis quinatis ternatifque

lineari-lanceolatis fubcarnolis obtulis. Linn.
Sp. plant. 1047.

2118 Crambe foliis laciniatis, caule credo ramofiffi-

mo. Did. Hort.

2119 Crepis fcliis amplexicaulibus Lyrato runcina-

tis. Hort. Cliff. 79.

2120 Cyno-

[ 93 ]

2120 Cynofurus fpicis quaternls obtulis patentibus

dimidiatis, calycibus mucronatis^ caule re-
pente. Linn, Sp. plant. io6.

2121 Cytilus floribus umbellatis terminalibus, cau-

libus eredlis, foliolis lanceolatis. Linn. Sp.
plant. 1042.

2122 Delphinium ne<flariis diphyllis.

2123 Dianthus floribus folitariis, fquamis calycinis

fubulatis tubam sequantibus, petalis multifi-
dis. Amcen. Acad. 4. p. 313.

2124 Dianthus floribus panicuiatis, fquamis calycinis

brevibus acuminatis, corollis multifido ca-
pillaribus, caule credo. Amoen. Acad. 4.
p. 272.

2125 Dipfacus foliis petlolatis appcndiculatis. Hort.

Upfal. 25.

2126 Genifla foliis ternatls fubtus villofls, peduncu-

lis lateralibus fubquinque floris foliolatis, le-
guminibus hirfutis. Amsen. Acad. 4. p.
284.

2127 Gentiana corollis quinquefidis hypocrateri-

formibus, fauce barbatis. Linn. Sp. plant,

334-

2128 Hieracium foliis lanceolatis amplexicaulibus

dentatis, floribus folitariis, calycibus laxis.
Hort, Cliff. 387.

2129 Innperatoria. Hort. Cliff. 103.

2130 Ifatis foliis omnibus dentatis. Linn. Sp. plant.

^ 937*

2131 Malpighia foliis ovatis integerrimis glabris, pe-

dunculis umbellatis. Hort, Cliff. 169,

2132 Mar

[ 9+ J

2132 Marrubiuni calycum limbis tubo longlorlbus

membranaceis, angulis majoribus rotunda-
tis. Linn. Sp. plant. 817.

2133 Matricaria foliis fimplicibus linearilanceolatis

feffilibus, pedunculis uniformis.

2134 Ocymum foliis lanceolatis ovatis ferratis race-

mis verticillatis. Linn. Sp. plant. 834.

2135 Plantago foliis ovatis glabris, fcapo angulato

fpica flofculis diftindtis. Linn. Sp. plant.
163.

2136 Potentilla foliis ternatis, caule dichotomo, pe-

dunculis axillaribus. Linn. Sp. plant. 71 5.

2137 Rofa germinibus ovatis glabris, pedunculis

cauleque hifpidis, petiolis inermibus frudli-
bus pendulis. Linn. Sp. plant. 705.

2138 Rudbeckia foliis inferioribus femilobatis incids,

caulinis trifidis vel quinquefidis, pedunculis
longiflimis.

2138 Scabiofa corollulis quadrifidis acqualibus, flori-
bus cernuis, foliis pinuatis, foliolis lanceola-
tis ferratis. Hort. Cliff*. 30.

2140 Serapias bulbis dbrofis, floribus eredtis braftca

longioribus. Linn. Sp. plant. 1345*

2141 Scolymus foliis margine incraffatis. Linn. Sp.

plant. 1 143.

2142 Scorzonera foliis omnibus runcinatis amplexi-

caulibus. Linn. Sp. plant. 1114.

2143 Sophora foliis pinuatis, foliolis numerofis ob-

longis villofis, caule herbacco. Linn. Sp.
plant. 533. _

2144 Statice fcapo dichotomo ancipiti foliis lanceola-

tis mucronatis, floribus aggregatis. Linn. Sp.
.plant 395.

2145 Ten-

[9^

214-5 Teucrlum foliis ovatis acute inclfoferratis gla-
bris, floribus axillaribus geminiscaule, eredto.
Linn. Sp. plant. 790.

2146 Tithymalus Linarias tolio, lunato flore. Mor.
H. Reg. Blefi

2147. Valeriana fylveftris major altera, fol. lucido.

H. Reg. Par.

2148. Veratrum racemo compolito, corollis paten-

tiffimis. Linn. Sp. plant. 1479.

2149 Veronica racernis lateralibus, foliis linear! lan-

ceolatis pinnato dentatis. Linn. Sp. plant. ,

2150 Volkameria ramis inermibus. Linn.Zeyl. 23 1.

XVI. A Courfe of Experhnents to afcertain
the Specific Buoyancy of Cork in different
Waters : The refpeBive W eights and Buoy-
ancy of Salt Water 'and Freff Water :
And for determming the exaSi Weight of
Huma?2 and other Bodies in Fluids. By
John AVilkinron, M. D. F. R. S, of
London and Gottingen.

[Experiments to determine the Specific Buoyancy of
Cork in River Wateri\

Experiment I.

Read March 14, ^ I X cubes of good cork, every one
«/6s* meafuring an inch fquare, as nearly

as they could poffibly be afcertained, with a gra-
duated

[ 96 3

duated gage of cork faftened to a point of each, fe-
verally weighed as follows ;

Grains

N* I 49

2 47 4-

3 47

4 46 i

5 46

6 43

Sum of Weights 279 4. Grains.

the medium weight, being the exact weight of a cubic
inch of cork is 46 ® .

Experiment If.

N® I, 2, 3, 4, formed a float named A, being 190
grains of cork, which was faftened to a medallion
oflead, weighing two ounces, by a wire that weighed
eight grains} thefe being put into a deep jar of
Thames water, taken above the new bridge, the lead
weighed exadily 44 grains} fo that 190 grains of
cork fupported precifely 916 grains of lead in river
water.

Experiment III.

The float was left in the fame water, immerfed by
the medallion for the fpace of 48 hours, with a view
of obtaining a precife knowledge of the quantity of
water the cork might imbibe } how its buoyancy
might be affeded } and how much extenfion it might
acquire from a certain continuance under the water.

[ 97 ]

It was fomewhat furpriiing to find, that after this
period of immerfion the cork had not, as might have
been expected, loft any force of buoyancy ; but on
the contrary, it had adtually gained two grains, and
was found to fupport 918 grains of lead: which
muft be attributed, it may be prefumed, to an ex-
panlion of the air contained in the cork, acquired
from its immerfion in the frefli water.

To be further informed how cork would be affcd:ed
by a continued immerfion, the fame float, after
weighing, was again immerfed in the fame water,
for the fpace of 48 hours longer. And now the water
was found to have penetrated its recefl'es and cavities,
in fo much that its buoyancy had decreafed 1 1 grains,
and it then only lupported 905 grains. This decreafe
may poflibly be attributed to a greater imbibition in
the cork, and a greater penetration given to the wa.-
ter, by its having been now 96 hours in a chamber,
with a'fire in it, by which it might be warmed. This
float A being taken out of the water, wiped, and
laid in a dry place for 24 hours, weighed 21 1 grains,
having gained by abforption 21 grains of additional
weight.

Experiment IV.

The float, in this ftate, having been 24 hours out
of the frefti water, was now put into fait water-
brought from the North Foreland, in which it was
found to fupport the weight of 954 grains, of a
leaden medallion, having the power of buoying up
38 grains more in the fea water, than it did in the
river water, with which it was nearly faturated at the
time of its immerfion in the fea water.

VoL. LV. O

After

[ 98 ]

After an immerfion of 48 hours in the fait water,
this flo^t (A) loft 1 6 grains of iis buoyant power; and
having been 72 hours in the fait water, upon weigh-
ing of it again out of the water, being wiped, but
full of water, it was found to weigh 241 grains,
having gained 30 grains. After being nine hours out
of the water, in a dry room, it weighed 213 grains,
having loft 28 grains. This float (A) having been
76 hours in the fait water, in which it then fuflained
949 grains of lead was removed, thus faturated
with the fea water, into a veflel of frefti river water,
and was found to fuftain 923 grains only, being
26 grains lefs than it bore up in the fait water; and
yet it muft be oblerved, that this float had been I'a-
turated with frefli water before it was immerfed in
the fait water.

Experiments made to difeover the Specific Buoyancy oj

Cork in Salt Water,

Experiment V.

Not content merely to know the buoyant power
of cork in frefh water, it was next tried in fea water.
Four cubes, being each an inch fquare on every fide,
made of the beft found compadl cork, with diftind^
gages made of cork, and adjoining, as in the pre-
ceding experiments, were prepared, each weighing
as follows j

Grains
N° I 42

2 42 .1

3 54

4 53

5 43

Amounting in all to 234 4 Crains.

thefe

[ 99 ]

thefe being united, formed one float (marked B) that
they might the nearer refemble the texture of the
cork jacket. A vefi'el of fea water taken up near the
North Foreland being then provided, the float was
found to fupport in it a leaden medallion weighing
1048 grains. When it had continued in the fea
water for 48 hours, it exadly fupported 1024 grains,
having, by being in the fait water, for that fpace of
time, loft 24 grains of its buoyant power.

From this experiment we learn, that the fait water
iniinuates more into the fubflance of cork than frefli
water doth, wliich may perhaps be attributed to its
oilynefs, oil being, as is very well known, more
fubtil and penetrating, than water ; it could not
therefoie be expecfted that the cork fliould therein
letain its force fo vigoroufly, for lb long a time, as
it doth in the frefli river water ; and, on weigh-
ing, it was found to lofe ^ of its buoyancy in 48
hours.

But then we are further to obferve from the above,
that the lea water fupports a greater weight, and gives
more buoyancy to the cork float than frelh water, in
the proportion of 353 to 359 ; for a float weighing 44
grains, lupporting 353 grains of lead in frefli water,
buoyed up 359 lead in the lea water, being

more by fix grains. And it is to be noted, that the
fea water taken up at the North Foreland is not fo
much irnpregnated v/ith tiie marine pidnciples, as that
which is taken up at a greater diflance from frelh
water rivers, which decreales in its buoyancy in

m

*

Vid.^ Macellinus. Pliny (Lib. xxxi. Cap. 7.) P.
(Lett. Millionaires, Odav. Edit.) jtnd Dr Hales

O 2

Bour,(i-cs

O

proper-

[ 100 ]

proportion to its vicinity to or mixture with rivers j for
on evaporating it yielded only two drachms and one
grain ol ialt to a pint, which is lefs by feven grains
than is yielded by that taken up at the Me of Wight.

Experiment VI.

The float B being continued in immerfion in fait
water for 72 hours, it had loft 26 grains more of
\ 0 ce, lofin^ in the fiift 48 hours 24, and

in the 24 fucceeding hours two grains only j from
which it appears, that, after the cork has been in the
water for 48 hours, its abfbrption becomes lefs than
before, in proportion as 12 isto i.

This float having continued in the water for 78
hours, each piece of cork, being wiped very drv on
its furface, but not fqueezed, weighed as follows j

]\° I weighed 55 4- Grains having gained 12 Grains

2 47

44-

3

66

12

4

59^

54-

5

51 4-

8i.

X

All 5 weigh. 2794

gained 424.

Being then deftrous to know if any quantity of
fait had infinuatcd into the pores of the cork, and if fo,
how much ; the above float was hung up to dry in
a warm airy room, where it was not far from the
fire, for the fpace of 48 hours j when it feemed to

he

[ 101 ]

be quite dry, and each piece being weighed, was found
as follows j

Gr. Gr.

N® I weighed 45 the fait fuppofed to be contained was 3

2 46 3-£

3 59 ^

4 55

5 44 ^

All 5 weigh. 249

fait gained 154

But on their being hung near a fire for 72 hours,
until perfedly dry, no fait appeared to be imbibed,
for the above numbers weighed as follows ; having
lofi: by extraordinary drynefs about of their firfi:
weight.

N° I weighed 40 Grains, having loft 2 Grains

2 42 4

3 54 3

4 53 3

5 43 3

232

15

Experiment VII.

For the fake of the greater exadnefs, another float
(marked C) was made of two cubes of cork, amount-
ing to 164 grains; the larger 118, and the fmaller
46 grains ; this was put kito the fame velTel of river
water, after it had been 96 hours in a warm cham-
ber, and fupported a medallion of lead weighing
766 grains ; it was left in the water for 36 hours
longer, and weighed again, when it was found to
fupport 754 grains, having loft 12 grains of its
buoyant force in that fpace of immerfion. From this
fecond experiment does it not appear, that this lofs

of

[ 102 ]

of buoyancy was principally owing to the warmth
the water had got by handing in a warm room, as
was hinted at before, which was further proved by the
thermometer ?

Two other floats, of 44 grains of cork each, having
been 72 hours in river water, weighed each 53 grains,
having gained nine grains by the immcrfion. Being
laid to dry for 24 hours after, weighed 46 grains,
having relinquifhed feven grains each.

The float C, being wiped and put into a dry place
for 24 hours, W'as found to weigh 183 grains, having
gained 19 grains of weight. The float, in this
hate, was thenimmeiTed in fait water, and was found
to fupport 864 grains, being 1 10 grains more than
it fupportcd in frefli water, after it had been faturated
therewith} C, being left in fait water 48 hours, was,
upon weighing, found to have loft fix grains of its
buoyant power. This float C, having been 72 hours
immerfed in the fea water, was found, after being
well wiped, to weigh 203 grains, having increafed
in weight 20 grains by immerfion. After being nine
hours out of the fait water it was found to weigh
188 grains, having loft in that time 15 grains.

Experiment VIII.

A medal of lead, weighing one drachm when out
of the water, was found, on being weighed in river
water, to be 54 grains and a half} being lefs by five
grains and a half than out of the water. The fame
medal being weighed in the fait w^ater was found
to weigh 53 grains and a half. The difference between
its hydroftatical weights being precifely one grain, or
more in river water than in fea water.

Expe-

[ 103 ]

Experiment IX.

A phial of river water weighed exactly 82 grains;
the fame veffel of fea water weighed exaftly 84; the
difference was two grains, or as 41 to 42.

Under all thefe experiments, thefe cubes of cork did
not feem to have gained any meafurable extenfion ;
yet it is certain the volume of cork, like mcft other
fubflances, will alter by the imbibition of humidity.

The affertion which has commonly been advanced,
that the bodies of men in general are fpecihcally
lighter than their refpedtive volumes of water, is not
quite perfectly founded in truth ; accurate experi-
ments, minutely obferved, will fatisfadtorily evince
the contrary to be true. Weighing hydrodically
the human body cannot be fo precifely performed,
as to permit us to draw any certain inference there-
from, as evidently 'appears from the imperfedt at-
tempts which the ingenious Mr. John Robinfon made
for that purpofe (fee Philofophical Tranfadl. Vol. L.
Part II. Page 30) ; on peruiing of which, and the
• author’s ingenuous confeffion of the inaccuracy of
his experiments, it occurred, that a naore concife
and eafy method of obtaining a certainty in this par-
ticular, might perhaps attend the following attempt
to difcover the fpecific gravity of the human body in
water.

Experiment X.

After having made the foregoing experiments,
with a view of afcertaining the fpecific buoyancy of
cork, and alfo the alteration it might undergo from
being immerfed in river or fea water, we proceeded
the more important exarnen, to difcover the pre-
cife quantity of cork neceffary to fuftain a man in the

water.

[ ]

water. For this end, 22 pieces of the heft cork,
fuch as is diredfed to be ufed for the jackets, ^ were
provided ; thefe were of different weights, from one
ounce down to one fcruple j fo that by means of a
firing to which they were occafionally faflened, one
might eafily learn what weight they would fufpend in
the water, and what weight they would not fufpend.
This being done, the next bufinefs was to find a
proper perfon to make the experiment upon ; for the
accuracy of which it was judged proper to felect a man
of the fmaller fize (as our le.imen are feldom large)
that was not very fat, becaufe fat people are more
buoyant than lean or bony perfons j one that could
fwim, that he might go through the experiment with
propriety, and without fear; one, therefore, was fixed
upon, who was plump and mufcular, not very bony,
but moderately lo;

Flis height was five feet two inches ;

His waifl meafured two feet ten inches ;

His weight was one hundred and four pounds.
Thus fitted out, he flripped naked, and ten ounces of
cork being tied about his neck and breafl, he committed
himlelf to the river Thames, near Chelfea, in a place
where the water was about a foot below his depth ;
but he could not keep his head above the furface
without employing his art, though he found not much
art required to do it : another ounce of cork was
therefore added, and he perceived himfelf raifed
thereby, fo as now to be the more able to keep
himfelf above the water, but yet he went flowly to
the bottom, unlels he took care by fwimming to pre-
vent it. For this reafon another ounce of cork was

* The cork jackets propofed for faving the lives of feamcii
and others in fhipwreck arc here meant.

applied,

[ ^05 3

applied, but fllll he funk, though more flowly than
before ; and it was plain to be obferved, that the
point between that manner of finking and fwimming
was balanced with fuch extreme nicety, that the
fmallefi; addition of cork would determine in favour
of buoyancy : accordingly half an ounce was added,
and this weight fupported him in a vibrating flate ;
but by the fuper-addition of one drachm and two
fcruples more of cork, he found himfelf very able to
keep above water, in a living pofition, without any
help from his art of fwimming, and that it required
fome fmall pains to immerfe himfelf. It therefore
refults from this experiment, that twelve ounces, five
drachms, and two fcruples, or 6100 grains of cork,
fupported this man in river water ; 6100 grains of
cork are equal to 163 cubic inches; which appears,
by a calculate drawn from the fecond of the foregoing
experiments, to be able to fupport 63 ounces, five
drachms, and eight grains of lead, which mufi: be,
therefore, the exadl weight of this man in river water.
By comparing this calculation with the above experi-
ment IV. made in the fea water, we fliall find that
this man weighed 60 ounces, three drachms, and 2t
grains; or four pounds, 12 ounces, three drachms,
and 21 grains, requiring 12 ounces and 21 grains
of cork to fupport him, in fea water. It mufi: how-
ever be obferved, as we have already intimated, that
the fame quantity of cork which fupports a fgt, or
very plump perfon, in the water, will not fuffice to
buoy up a lean perfon, although their weights, out of
the water, be equal.

VoL. LV.

P

XVII.

[ ]

XVII. An Account of the Dtfeafe^ called
Ergot, in French, from its fuppofed Caufe^
viz. vitiated Rye, In a Letter from
Dr. Tiflbt, of Laufanne, to George Baker,
M. D. F. R. S. Cotmnunicated in a Let-
ter from Dr. Baker to the Rev. Thomas
Birch, D. D. Sec. R.

Reverend Sir,

IN the month of April, 1762, my late moft amia-
ble and very ingenious friend, Dr. Wolladon,.
preiented to the Royal Society the hiftory of an ex-
traordinary cafe of a mortification of limbs in a poor
family at Wattifliam, about fixteen miles from Bury,
in Suffolk, where Dr. Wollaflon at that time refided.
About the fame time the Rev. Mr. Bones, then mi-
nifter of the parifli of Wattifliam (whofe humanity
led him to iliew a particular attention to the fuffer-
ings of that unhappy family) tranfmitted to me every
circumflance, which he could obferve or colle6f, re-
lating to the difeafe. The letters, which I received
on this fubjec^, from Mr. Bones, were communT-
cated to the Society ; and both accounts were pub-
lifhed in the fecond part of the fiifty-fecond volume of
the I’hilofophical Tranfad'ions for the year 1762.

Some time in the lafl winter, as I was perufing a
work, intitled, Avis an Pcuple pir J'a Jiinte par M.

[ 107 ]

^ijjotj Medectriy Memhre des Soctetes de Londres & de
Bale^ (printed at Paris in 1762) I obferved a difeafe
mentioned under the appellation of Ergot, a name
borrowed from its fuppofed caufe, viz. vitiated rye.
As the phasnomena of the difeafe defcribed (which
is faid to be frequently epidemic in feveral provinces
of France) are very fimilar to thofe of the difeafe,
which we lately received an account from Wat-
tifham, I took the liberty of writing a letter to M.
TifTot, and requefled the favour of him to commu-
nicate to me whatever had fallen under his own ob-
fervation, with refped to the difeafe called Ergot.

In anfwer to my letter, I have lately been favoured
by that learned phyiician, with the inclofed collec-
tion of curious fads and obfervations on the fubjedt
of my inquiry : which, at his requeft, I do myfelf
the honour to fend to the Royal Society,

I am,

Reverend Sir,

Your mod obedient

and very humble fervant,

George Baker,

jermyn-ftreef, Dec. 5, 1764.

C io8 ]

Viro celeberrtmo et eruditifftmo G, Baker A. T’ijfot S, D,

Read March 21, V O D bene de libellis meis fen-
V,^ tias impenfe laetor, vir egregie ;
gratufque accepi, nec fine magno emolumento meo
Jegi perlegique optimum tuum libellum de dyfente-
ria et catarrho.

Mea non fijnt, fed anonymi editoris Parifienfis,
quae leguntur de fecali cornuto, in confiliis meis de
populi fanitate. Hie capitulus et omnes alii de variis
chronicis morbis, a pag. 420 — 504, additamenta funt
ejufdem aiidtoris, quae lepofui in fecunda editione
Laufannenfi, prima tamen longe audtiori, et quam '
anglice verti curarunt typographi veftri Cl. Becket
et de Hondt. Scopo tamen tibi complacendi lu-
bens mitto quae quondam, dum varias partes diaete-
tices paulo curiofius indagabam, de hac materia col-
legeram ; quae omnia, fi lubet, nec indigna videntur,
meo nomine, in conventibus illufiriflimae focietatis le-
gere poteris.

Tria funt praecipua vitia granorum frumenti et
fecalis, rubigo^ njtilago^ et J'ecale corniitum. Mira
ubique fere invenitur confufio de illis morbis, et prae-
fertim duobus primis j illos paulo prcfiius definire cx-
pediet.

Rubigo, vobis, ut video, mildew^ Gallice rouilky
Italice ruggine^ pulvis efi; flavo-rubefeens, glutinofus,
qui adhaerens et culmo et glumae plurium plantaruni
graminacearum, earum incrementum impedit, indc
male nutritum granum atrophia conficitur et exficca-
tur, nullam, aut fere nullam,farinam praebens. Hie
eft morbus, ni fillor, quern in nonnullis locis

dicun t

[ 109 ]

dkunt hied vante \ ventum calidam granum credit
comedifle vulgus.

Udilago, Gallice, tnille ou bruIurCt Italice fuligine^
nomen efl genericum, nigram fmmentorum degene-
rationem defignans ; duas funt fpecies, carbunculus
le charbon^ et caries la carte.

Carbo morbus eft grani, vix externe nofcendus, nift
quod- grana rotundiora videntur, quo interna fubftan-
tia vertitur in nigrum, vifcidum, foetidum pulverem,.
Carbunculata grana multum aliquoties turgent. Mor-
bum hunc dixit bojfe cl. Duhamel. Facillime ob-
fervatur carbunculi natura in grano tritici. Indici
(Maiis) monentecl. Bonet [^]. Viditenim quae ovum
gallinaceum aequabant, plena pulvere nigro, foetido,
faniofo, variis lamellis diftindto.

Caries, quam plerumque generis nomine nielle de-
ftgnant, frumentiim, fecale plurefque alias plantas
inficit, non granis tantum, fed floribus et foliis in-
feftus fub forma pulveris nigri, vifcidi, undiquaqiie
adhasrentis, et quidquid tangit necantis j invadere vi-
detur morbus quo tempore floret frumentum, ficque
nunquam adolefcit granum ; adultum enim corrumpi
baud facile crederem. Coram habeo plures ariftas
carie tadfas, quae pulvere illo undiquaque fufcata; gra-
noque penitus vacuae, folas glumas exhibent albefcentes,
et nefcio quid fibrofl, in media gluma, quod videtur
fuifte pars fibrofa aut ftamen grani. Nonnullas tibi
mitto ; parum faporis aut odoris habet ille pulvis, nec
plus habuit quo momento colligebatur.

Rechcrches fur 1’ ufage des feuiilcs dans les plantcs,.

pag- 327-

Caiiem

_ [ ”0 ]

Caiiem omni aevo obfervatam falfTe credit cl.
Ginanni; carbo vero recentius cognitus, nunquam
vifus fuerat in Lombardia ante annum 1730, et
CefennjE ante annum 1738.

Secale cornutum, ergots morbus eft longe alius,
folumqiie lecale vel duas aut tres alias plantas grami-
naceas Alpinas, ut narravit illuft. amicus meus Hallerus,
infeftans. Vegetatio eft irregularis grani fecalini, quod
fubftantiam quaft mediam inter granum et folium
adipifcitur, coloris, iit vidi, licet rariflime (raro eniin
in noftris regionibus crcfcit) fufce viridis irregulari-
ter comprefti, et, utolim jam videruntcl. Marchand
et Vaillant, faspe quatuordecim aut quindecim lineas
longum, duas latum. Prae aliis ilia grana accura-
tiftime defcripfit Car. Nic. Langius, additisetiam ex-
perimentis de illorum indole. Sata nequaquam ger-
minant; abundant annis prasfertim pluviofis j etquan-
do pluviofum ver calidiffima aeftas excipit [^].

Simplicia base videntur; at, ut jamdixi, ex nomi-
num confufione plures nati funt errores. Semper
notam fuifte rubiginem dubitarc vetant antiquiftima
monumenta. Veteribus nota fuit quoque uftilago,
apud illos fuligo aut uredo didla ; fed turn an-
tiquis turn recentioribus fasculis paflim ufurpatarn
rubiginem pro uftilagine, et viciflim uftilaginem pro
rubigine queritur, qui dodiflime de morhis gra?ii in
berhd feripfit, Cl. Comes Ginanni [c~\ j firmiterque

[Z>] Opus Langii, fenatoris et mcdici Lucernenfis, German!-
cc Icriptum prodiit Lucernae anno 1717. Vis tituli eft Deferip^
tio tnorborum cx efu clavorutn fecalinorurn cum pane. Bonum ex-
cerptum invenitur in adlis eruditorum ann. 1718. pag. 309.

[f] Delle 7nalaitie del gram in berba trattato jloi'iio 4.'° in

Pefaro, 1759.

1

credit

[ 3

credit rubiginem a Ramazzino defcriptam, in con-
ftitutione epidemica anni 1692, veram fuifle uftila-
ginem. C^eritur nonnullos prasdicalTe audader de
iiftilagine quod folius eft rubiginis, quam veteres asru-
ginem quoque dixerunt. Horum locos fufe adducit,
a quibus abunde patet, uredinem aut fuliginem (re-
centior eft enim vox uftilago) primis aevis, quod dixi,
notam quidem fuiffe, at tantum obfcure.

De nomenclatura fecalis cornuti minor confufio ;
aliis quidem fecale luxurians, aliis mater fecalis quod
eft ;«//!/‘/f;7^(??7zGermanorum, aliis orga^ Langio Clavus
Secalinus dicitur, at cum aliis morbis vix confundi
poteft. Solus forfan errorem interponit Cl. Ma-
NETA, qui fecale cornutum nihil aliud effe affirmat
quam gigantea grana, ex nimio incremento in fera-
cibus annis, quas nihil nociVi habent, additque, contra
omnes, hordeumet frumentum cornuta fieri pofTe [^];
at fane nunquam fecale cornutum vidit bonus vir, fed
grana ilia vere gigantea nullo vitio nifi nimio volumi-
ne fa-da et omni anno ubique obvia. Fcemina, cu-
jus epiftolam pofteris tradidit Cl. Salerne [<?], dicit
quoque fecale cornutum aliquoties majus, aliquoties
minus efte fecali vulgari ; ct Cl. Hanovius [y ] cre-
dere quoque videtur fecale cornutum morbum efle
aliquoties marafmoideum ; fed hifce tribus diflentiunt
omnes alii.

f^/J Cotnmentar. de relus In hijlor. natural, etmed. gejih-t tom. Ill,
p. 520.

[e] Mcmoire fur les maladies que caufe la feigle ergotte, dans
iis memoirs de mathemaliquc et de phyfique prej^ntes d d academic
Royalc des Sciences, tom. II. p. i6i.

[ /' ] Comment, de reb. in hi/i. he. iibi fupra.

Quoties

[ ”2 ]

Qi^tles ergo de rubigiiie, uftilagine, aut fecali cor-
nuto agitur, probe tenendum rubiginem, airuginem,
riiggine, rohhiga^ mildew ^ rouille^ Jiic mielU et forfan
bledvantey unum effe morbum j- uftilaginem, uredi-
nem, fuliginem nigellam, volpe^ nielle^ brulure aii-
um efle diverfum morbum, qui fuas habet fpecies, ca-
riem et carbqnculum ; fecale demum cornutum, fe-
cale luxurians, matrem fecalis, mutterkorn^ orgam,
clavum fecalinum, tertium efTe genus morbi pri-
mis omnino diffimile.

Nocivum prasbere alimentum omnia corrupta gra-
ua non nefciverunt antiqui ; et pulchra babet pras-
cepta, etiam nunc in diasteticis princeps, Galenus,
de damnis frumenti nigri, id eft, uftilaginis, et lolii,
quibus uti piftores f'erio vetat, memorans fimul
morbos quos inde natos vidit

Panis confedtus ex frumentis quae feedavit pulvis ni-
gellae, aut quae carbunculata fuerunt (nondiim enim
videie contigitgrana partim cariofii, partim fana) ma-
ligne femper fermentat et coquitur, vifeidus eft, gra-
vis, inaftuetis nauTeoftis j et anno 1758, cum hie
abundaverit, plurium, ni fefellit obfervatio, mOrbo-
rum chronicorum abdominis et cutis caui'a extitit.
Vidit Longolius virum, qui, devoratis, curiofitate,
granis aliquot frumenti uftilaginei, doloribus mern-
brorum corripiebatur, et aliquot dejedtionibus fana-
tus eft.

At pejjhna funt damna quse ex efu fecal is cor-
nuti oriuntur, et cum verifimile lit hanc fecalis dege-
nerationem omnis aevi fuiiTe, credere aulim morbos
quos ciet, omni ajvo aliquot mortales tetigilfe, utut

De almeniorum facultatibus^ 1. i. c. 37.

4

illos

[ /I3 3

illos mlnime defcripferint veteres medic! ; primurtl
enim accurate defcripti funt anno 1596, et ab illo
tempore dire in varias Europse regiones aut fpafmos
aut gangrasnam excitantes faevierunt. Breviter et hifto-
rice illas clades recenfebo. F. Hofmann us utram-
que morbi faciem adumbrat [/:>]. Spafmodicam pri-^
mum, turn gangraenofam delineabo. Anno. 1596,
in Haflia etVicinis regionibus, graflatus eft epidemice
morbus fpafmodico-convuUivus, cujus caufam ufui
iecalis cornuti tribuit facultas rqedica Marpurgen(is>
qua?, anno 1597, libellum edidit, Germanice, dc
fymptomatibus, aetiologia, et curatione hujufee mor-
bi j in quo haufide videtur Sennertus [z]. E fufa de-
feriptione, in audlore omnium manibus trito, facile
invenienda pauca tantum memorabilia excerpam.

1. Qui epilepfia corripiebantur, vix omnino hoc
morbo in pofterum liberabantur.

2. Qui amentes fiebant, ftupidi ad mortem ufquc
remanebant.

3. Eicet nonnulli poft hunc morbum ad quinde-
cimum^'annum fuperftites fuerint, ftngulis tamen
annis, menfe, Januarii et Februarii, male fc habe-
bant.

4. Contagio non immunis erat morbus j quod
nufquam alibi obfervatum.

Idem morbus annis 1648, 1649, 1675, in

Voigtlandia, tefte Hofmanno, graftabatur. Anno
1702 totum Freibergenfem tradtatum peragravit*
Anno 1716 Saxoniam et Lufatiam afflixit, quam epi-

Patholog. general, part, ii. cap. ix. § 1 6. in febolio. ^

[/'] De febribusy libr, iv, cap. xiv. d< febre maligna cum
fpafmo.

VoL. LV.

Q

demiam

C 114 ]

demlam defcripfit G. V. Vedelius [^]. Eodem
tempore A. O. Goelike difTertationem edidit de
eodem morbo, in qua omnes, qui tunc extabant de
hoc morbo audlores (quos inter Hordius, Buddasus,
Longolius, Haberkorn, Willifh, aliique) fedulo ex-
cerpdt [/], difFerentiarque morbi in variis epidemicis
curiofe indicavit.

Idem morbus anno 1717, varios Germanias locos
tetigit. Silefiam anno 1722 invafit. Inde nata
Vateri Differtatio f///]. Dynaftiam Sabothi in
Sileda et tradlum Vartembergenfem in Bohemia,
anno 1736 occupabat. Sabothi epidemiam defcripfit,
at, maximam partem, Germanice G. H. Burghart
[«]. Morbum Vartenbergenfem accurate pinxit J. A.
Srinc [(?] qui folus quingentos aagros vifitavit. Haec
erat facies morbi. “ Incipiebat molefia- titillatione
“ pedum referente formicarum perreptationem ; mox
ventriculus gravi torquebatur cardialgia. Hinc ad
“ manus malum procedit, donee tandem ipfum caput
occLipet. Titillationem ejufmodi non manuum
tantum extremique pedis fed et utriufque membri
” digitorum fequitur contra<ftio, quam vir robufiif*
fimus vix impedire valeat, adeo ut varie diflradlos
artus jurares luxari. Uri pedes manufque altis
fignificant clamoribus, corpore fudoribus diffluente-
“ largifiimis. Grave fit poft dolores caput, et ver-

DiJJertatio de morbo fpafmodico epidemico maligno in Saxo-^
mid, Lufatid, vici'nifqtte locis grajfato. yenee 1717.

[/j A. O. Goelike horct fubfeeijives, tom. ii.

[wj Chr. Vateri DiJJertaiio de morbo fpaf?nodico popuhui
SiUfiaco. IVitcbergee 1723.

[«] Satyres medicorum Silejiacorum, Specim. iii. obf. 4.

[o] Satyree meddeor, Silef. Spec. iv. obf. 5.

4

tigine

C “5 ]

tigine corrlpltur : Nebulae oculis obvnsrfantm*.
Nonnulli vel plane csecutiunt, vel quse fmguia
“ occnrmnt, bina fe videre auturnant. Oblivifcuntar
“ fe, et ebriorum inftar vaciilant, mentis minime
“ compotes. Quidam maniaci fiebant, alii melan-
colici, alii comatofi. Qui decimum quintum tetatis
annum fuperarunt, morbo comitiali funt obnoxii.
Horum plerique fatis concedunt. Comitatur id
“ malum opifthotonos, et fpuma ex ore profluit fub-
cruenta aut davo viridive colore tindta. Lingua
convuldonibus ftepe lacerabatur ; quibufdam adeo
‘‘ intumuit ut vox interciperetur, faliva effluente
“ copioliflima. Cardialgia tentatos, fubfequuta vo-
mitum epilepfia, mortem vidi oppetere. Qui pofl
titillationem horroreet frigore obriguerant, eorum-
‘‘ dem manus pedefque minus diftendebantur. Uni-
verfa base malorum ilias pedifequam habet bu-
“ limum. Plurimi fatiari nequeunt, pauciffimi cibos
averfantur. In unius cervice bubones nafeeban-
‘‘ tur, ii tamen ad peftem minime referendi. Ex
‘‘ his pus flavum effluxit, inter immanes et urentes
plane dolores. Macula3 in alterius pedibus efHo-
ruere, pulicum morlibus fimiles, qute in odavam
“ hebdomadam perdurant. Quorundam facies tur-
piter feedata eft maculis. Pulfus fanorum fimilis,
“ nullo excepto. Excipiebat fpafmos rigor artuum :
ut pedibus manibufque capti viderentur. Apud
“ alios duarum ; apud alios quatuor ; apud alios fex
odtove j imo apud nonnullos duodecim hebdo-
“ madarum fpacio dirus hie affedlus fuam ludit fa-
“ bulam j funt et illi fua interfeenia, quibus segrotos
“ finit quiefeere. Pericrunt inde ab initio ejus ho~
mines centum, maximam partem infantes. Inter

Q_2 quingentos

[' ”6 ] .

quingentos fcliicet aegrotos infantes trecenti occur-
runt 3 ad decimum vero quintum annum astatem in-
“ fantum numero. Duarum domuum incolas ad
plures abiere, nullo plane fuperftite. Contagionein
non adelTe Deum teftor.”

“ Horrenda fymptomata, ai't Burghard, atque
‘‘ fpafmi extremas corporis partes, brachia videlicet,
pedes, caput, oculos, labia mirum in ■ modum
convellentes, omnem rationis ufum delerites, nullis
‘‘ compefci'potuerunt praefidiis. Rarb ante tertiam
feptimanam, morbus quicquam remittebat,' plures
“ vero qui praefertim neque medicamenfis utebantur,
“ neque conveniens regimen obfervare voluerunt>
“ ad unum vel alterum menlem detinuit, Qmbus
“ febris, continua quafi, fuperveniebat, largos, pras-
** fertim tarn poll: febriles quam fpaflicos paroxyfmos,.

eliciens fudores, hi citius evaferunt. Qm autem
“ rnoriebantur paulo ante deceffum refolutionem'
“ membrorum paralytoidem, imo et ipfam apoplexiam '
“ videbantur pad. Feminis prolixiores inducias'
“ conceffit morbus, tunc demum eo vefwmentiuS
“ furens quum menftruum veddgal elTet folvendlim L
** hoc foluto praeter - ingentem vfrium proftrationem'
per aliquot feptimanas parura conqueftaj funt, do-
“ nec rediens luna novas refufcitavit turbas.”

Quibus demum evadere datum, his per notabile
“ temporis intervallum membrorum debilitas, imo
unius vel alterius quad rigor et movendi quadam
“ impotentia mentifque torpor.”

Anno demum 1741, Novam Marchiam ingredtiS'
hanc regionem ufque ad menfem Maium aniii i742>*
prefiit idem morbus, quern graphice pinxit Cll‘

'Muller*

[ ”7 ]

Muller [/>], cujus accuratilUma defcriptio ledu
digna eft. Eadem initia^ incrementa, fymptomata
couvulfiva et paralytica, eamdem pertinaciam, eum-
dem exitum ac in defcriptione Srinici invenies, fed
perpetuus comes hie adfuit febris asgrotis Bohemenfi-
bus ignota.

An ab illo tempore novas regiones devaftaverit ilia
calamitas nefcio ; jamque, optime Bakere, ad aliud
genus morbi quod inducit fecale cornutum, gangrae-
nam nimirum fpontaneam, accedo.

Ex variis quas collegi, conftat hunc morbum in
nonnullis Galliae provinciis jam noturn fuifte anno
1630, ut teftabatur Doftor Thuilier, fummi illius
viri Duds de Sully medicus [^]. Annis 1650, 1670,.
1674, vigebat in nonnullis locis Aquitaniae, in So-
lonia,.tradu Gathienji et, anno fpeciatim 1674, men-
tis Argifi^ tefte Cl. Perrault [r]. '

Primum fymptoma erat torpor crurum, turn dolor
cum levi tumore fine inflammatione, et cita fuc-
ceftione, frigus, livor, fphacelus, membri excifio.
In Solonia nulla aderat et febris, mites erant dolores.
Nulla adhibebant auxilia i fed nafus, digita, manus,
brachium, pedes, crus, femur, fponte fphacelata
excidebant.

Anno 1695, illuftris ille medicus J.. C..Brunn,
vidit, Anguftas: Vindelicorum, foeminam morbo fpaf-
modico et fphaccio manuum laborantem, ex efu feca-

[ /) ] C. A. a Bergen et J. M. F. Mulleri Difputailo de. morh.
f.pid.fp‘’f’^- co^tvidf.. -contain experte^ Francofurti ad Viadrum, 1742,-
utiiis diilerfatio in collcdUone pradlica Hallcriana reperiunda.

Lettre de M. Dodart au jounialiji des Scavants., ann..
1676. tom. IV, p. 79.

['•] 'Journ. des Sfavants^ ib. .

lis

Hs cornuti, ad caetera bene fe habentem; et did!-
cit a chirurgo, qui illam comitabatur, et qui nnper-
rime pedem ex eadem caufa Iphacelatum amputaverat,
degener illiid friimenti genus cauj'am quod incolce,
Jyhc:e Hercyniae non tantum convulfionibus tententur mirisy
fed et extrema jphacelo emoriantur [j].

Anno 1709, eadem calamitas Soloniam iterum in-
vafit, quae raro fecali cornuto omnino caret, led hoc
anno quarta pars fecalis cornuta erat. Cl. Noel
Chirurgus Nolbcomii Aurelianenlis L'hoteli Dieu^ in-
* tra annum, in nofocomio ultra quinquaginta £Egros,
ergothy ut dicunt, vilitavit, aut homines aut pueros,
nullam foeminam, pauciflimas puellas [^]. Morbus
incipiebat fere in digitis pedum (unicus manu pre-
henfus fuit) fajpe ad fummum femur extcndebatur.
Primum fymptomapoft ufumpanis venenati eratfpecies
"ebrietatis. Quatuor mortui funt poll amputationem,
gangraena ad truncum ulque ferpente, quod mihi
novum videtur argumentum quo demonftratur pericu-
lum amputationis antcquam conftiterit gangrsena.
PIa3C amputatio eft aeque nociva ac reprefiio fudorum
criticorum in morbo venenofo. Btefarum ftevus ac-
cidit cafus quern fic narrat ill. Fontenelle. “ Un
“ Pai'fan fut attaque de la maniere la plus cruelle : la
“ gangrene lui fit tomber d’abord tous Ics doights d’un
‘‘ pied, enfuitte ceux de I’autre, apres cela le refte des
“ deux pied, et enfin les chairs des deux jambes, et celle
“ des deux cuifles fe detacherent fuccelftvement et ne
“ lailTerent que les os. Dans le temps qu’onen ecrivit
“ la relation les cavites des os deshanches commen^oient
a fe remplir de bonnes chairs qui renaiffoicnt [7^].’’

[j] ASi. Cnriofor. Natur. Decur. tejl. arm. 2. obf. 224.
f/1 H'lftotrc dc V Academic Rcyale des Sc. am. 1710. p. 80.

[«] Ibid p. 81.

EoJcin

[ II9 ]

Eodem anno, faevifTimo gelu ubique gentium
famoliffimo, idem morbus in Lucernenli ftatu pri-
mum erupit et iterum annis 1715 et 1716, fimulque
Tigurinas et Bernenfes ditiones invalit ; h$c eft epi-
demia quam narravit Langius. “ Abfque ulla fe-
bre, ut plurimum poft pra^viam plus minus diu-
“ turnam laftitudinem, mortales male multabat.
Scilicet artus frigore correpti pallorem atque rugas
contrahebant, baud fecus ac ft calida3 diutius aqu$
fuiftent immerft, venis lub rugofa cute difparenti-
“ bus. Hinc torpidi omnique orbati fenftbilitate, fti-
“ perftite tamen, difiiciliore licet, motu, dolore in-
“ terno cruciabantur atrociflimo, qui ex atmofphas-
“ ra: aut ledi calore enormiter augebatur 3 in frigi-
“ diori verb loco aliquatenus remittens lenfationi fri-
giditatis vix tolerand^ cedebat. Senfus hie adeo
“ moleftus ab extremitatibus partium ortus fenftm
“ atque fenftm fe diffundebat, et afeendendo poft-
“ digitos in manibus braebia et humeros, in pe-
“ dibus crura et femora occupabat, donee fuper-
“ veniente fpbacelo pars afteda marcida nigraque
“ vel e trunco vel vicino membro delaberetur. Fu-
“ erunt qui omni dolore expertes unum alterumque
digiti articulum fpbacelo correptum et delapfum in
chirothecis vel tibialibus invenerunt. Sub morbr
decurfu reliqus corporis partes fatis bene valebant,

“ nib quod fub doloris incremento levem asftum fe-
brilem, fub paftu ciborum calidorum, fudorem a-
capite ad fcrobiculum ufque cordis, fomnos labo-
“ riofos, infomniaque turbulentaperpelli ftnt regri

Ab

[a-J Asia erudttoru7nyann. 1718. p. 309.

[ 120 ]

Ab illo tempore in Helvetia hunc morbmn obfer-
vatum fuiffe non novi ; fed ab anno 1709, intra fpa-
tium triginta annoruni ter aut quater epidemice de~
currens, in Nolbcomio Aurelianenfi, a Cl. Noel ob-
fervatus eft [^’]. ' i . * ' > • >

Endemicus eft, ut videtur, in illis regionibu.a.. ' In
adis enim Academic regiae Scientiarum Parifienlisde-^
gitur hiftoria epidemise ejufdem generis, a Ci. Duha-
MEL, ex relatione Cl. Mulcaille defcripta,
lane indolis, longe enim maxima pars aegrorum peri-
bat. 11 regne en Sologne depuis la moiftbn une
“ maladie appellee nom qu’on lui a ftonne a

“ caufe de la figure d’un grain qui la produit qui
relfemble a un ergot de volaille, c eft un feigle
degenere, dont Tufage donne a la mafle du fang
“ une qualite putride et gangreneufe, qui fe fait
“ d abord fentir dans les pieds et dans les jamh'es par
des laftitudes douloureufes et de lividite extcricure
« qui forme une gangrene plus fecbe qu humide ; il
s’y engendre fouvent des vers'; cnfin les doights
des pieds fe detachent de leurs articulations et
“ tombent avec le metatarfe; enfuite le pied, la jamb
“ et jufques au femur, qui abandonne la cavite co-
“ tyloidej il en arrive autant aux extremites fupe-
“ rieures, et on a vu a L’hotel Dieu des gens n’ayants
“ plus que le tronc, vivre neanmoins plufieurs fe-
“ maines ; car ccs chuttes des membres ne font jamais
“ fuivis d’hemorrhagie. Jufques id on n’a pas reufli
“ a guerir de ces malades 5 il en a peri plus de
“ foixante [2^].”

[ >'] p. 408.

[z] Mem. d( V R. da Sden. ann, 1748. p. 528.
• 2

Allam

[ I2<1 ]

Aliam epldemlam defcriplit Cl. Sal erne [a], cu-
jus haec erant praecipua phaenomena.

I. Omnes aetates et fexus invafit. Supra genu
non afcendebat : dum anno praeterito, iile forfan de quo
Cl. Mulcaille fcripfit, puer decennalis, qui duo
femora amidt, et frater, quatuordecennalis, ex al-
tera parte femur, ex altera crus ; ambo pod: 28 dies
perierunt. 3. PaucifTimi qui evadunt, raro tamen
diu fuperftites vivunt. 4. Amputatio mortem citat.

5. E centum et viginti aegris vix quatuor aut quinquc
evaferunt; omnes alii intra fex menfes perierunt.

6. Sanguis admodum vifcidus vix a vena ftillabat.

7. Inflammatio cutis locum fuppurationis prasfagit.

8. Poll: amputationem neque tornatili neque ligatura
opus. 9. Frequentius pedes invadit morbus in So-
lonia, paludofa regione. 10. Omnes aegri ab initio
fere imbecilli hiftoriam morbi tradere nefciunt j fla-
vefcit facies et adeo marcefcunt ut cadavera vide-
antur. ii. Morbus ncquaquam eft contagiofus.

Cl. PuY, Chirurgus primarius Nofocomii Lugdu-
nenfis L' hotel Dieu^ mihi narrabat fe ibi vidifte fub-
inde, et Temper imbrofis annis, aliquot aegros hoc
morbo laborantes, a vicinis agris addudlos, quos inter
faeminam cui duo exciderant femora. Symptoma dc
quo anxie queruntur eft urens ignis in parte. Addebat
fc audivifte morbum aliquoties obfervari in Del-
phinatu.

Non folis hominibus nocet fecale cornutum, fed.
animalia quoque venenat.

In Wartembergenft tradlu ex illius efu aborturn
faciebant fties j peribant mufcae.

[fl] Memoirs de MathmaU et Phyf. prefent. a TJcadem. Rsy.
des Sc. tom. II. p. 155,

VoL, LV. R Narrat

R

[ 122 ]

Narrat Srincus canem nutritum pane e puro fecali
cornuto confe6lo intra horrendos ipafmos periifle.
Alii medici idem experimentum fecerunt cumporcis,
anferibus, gallinis. Idem fuit eventus [b'\.

Convulli quoque perierunt cervi qui fecale cornu-
tum comederant [pi,

Vidit Cl. Salerne porcum, hoc fecali, cum du-
plici hordei parte, aliquandiu paftum, qui periit cum
abdomine tumido, duro, nigro, cruribufque foede
ulceratis ; hepate autem et inteftini partim gangraenofis.
Alio, ob furfur fecalis cornuti comeftum, quatuor
pedes et duae aures exciderunt. Anates nonnulli
inde peffime fe habuerunt, et duo fat cito perierunt.

Plura quaeri poffunt. i. Quaenam eft caufa hujufee
degenerationis fecalis ? Summa hie adhuc caligo.
Cl. Aimen demonftravit cariem oriri ex feminibus
fitu foedatis [^] et promifit inquirere in caufas fecalis
corniculati. Num fidem folverit in quarto tomo,
quern nondum vidi, nefeio.

2. Quomodo nocet fecale cornutum? Fiat lux.
Plura nofeimus venena vegetabilia quorum modum
agendi ne minimum intelligimus ; tale eft fecale cor-
nutum : naufeofo pollet et acri fapore ; talis eft fapor
plurium venenorum necroticorum j in genere vide-
tur hoc fecale hu mores noftros inficere veneno inqui-
lino, quod aut nervos laceftens fpafmos, aut fangui-
ncm putrefaciens gangraenam excitat. Plura nefeio.

3. Quomodo nocet nigella ? Acre eft venenum
et vifeidum ; at ft quis nudis pedibus in pratis nigella

[Z>] Sat. Med, Silef. uhi fup. p. 57.

[c] Muller, § xiv. 33.

r^j Mem. prefent. tom. III. p. 68.

obdu(ftis

[ 123 ]

obdudlis obambulat, foeda inde cruriim ulcerem re-
portabit [f].

4. Cur modo fpafmos, modo gangriEnam, aut
cum febre, aut plerumque fine febre, excitat hoc ve-
nenum ? Res eft altioris indaginis, nec fperanda fo-
lutio nifi ex innuineris obfervationibus et experimen-
tis, de quibus hue ufque ne quidem, fomniatum eft.
In genere tota hasc hiftoria, hand fat nota et per-
penfa, digniflima eft attentione medicorum ; piura
enim phaenomena habet quas, bene intclledta, multum
iucis in medicinae difficiliora radiarent.

Qi^ de medela novi breviter nunc recenfebo.

Marburgenfes purgabant, turn amara fudorifica
iargiter prasferibebant.

Longolius acida fuafit.

Langius emefim initio adhibebat, et, emefi per-
aefta, fudorifera amara ; omniaque cavere juffit ali-
menta vifeofa, pinguia aliaque dufpepta. Omnes
ftrenue interdixere pane calido, quern longe perni-
ciofiorem fenefeente ubique demonftravit obfervatio.
Ipfum granum tempore virus amittit j inde frequens
epidemia mox poft mefiTem, fenfim rarefeit et de-
mum penitus celTat, utcumque non defit fecale cor-
nu turn.

Mulleri laxa eftet inermis medicina ex inanibus
antifpafmodicis j redle vero veficatoria adhibuit.

In Solonia mitefeunt dolores venae fedlione ; de-
codtum vitrioli, aluminis, et falis communis gangrae-
nam incipientem aliquoties fiftit [/'j.

In puero, crus gangraenofum Iargiter ad ofTa uf-
que incidebat Cl. Puy, tuneque acerbe dolens os

[<?■] Langius uhi fup. p. 313.

r/l Memoir, pref. tom. II. p. 162.

R 2 tibis

[ >24 ]

tibias varils terebratlonibus perforabat j' totum fere exT-
cidit putridum os ; fed fenfim totum callo regenera^
batur, novifque fuccrefcentibus carnibus integre refli-
tutus eft aeger^

Si de morbo ignoto conjedturas proponere liceret,
pracmifta, pro calii, V.. S. emefim ex ypocacuana et
tbrfan repetitam excitarem ; cum fale amaro purga-
rem, turn largas dofes camphors, elixirii vitrioli et
corticis Peruviani cum decodto chamaemeli propina-
rem j larga veficatoria et cervici et ofli facro apponi
curarem, lateque incifas partes aegrotantes, continuo
decodto vinofo corticis Peruviani foverem.

Anne haec gangraena fat accurate didta gangraena
iiftilaginea ? nequaquam.

Anne morbus ardejitiufn ? hie morbus videtur fu-
ifle Eryfipelas ia gangraenam faepe definens. Dixit
CJ. PuY earn efte aliquoties morbi faciem in Delphir
natu.

Anne gangraena, quae tam acerbe faeviit in fami-
liam J. Downing, in pago Wattisham menfe
Jauarii anni 1762; et quam deferipferunt Cl. Bones
1^] Wollaston [^] et Parsons [/], eft idem
morbus ?

Pater, mater, fex pueri, corripluntur doloribus
acerbiflimis crurum, pedum, femorura, valente reli-
quocorpore; nigrefeunt, gangrasnofae excidunt par-
tes 3 folus felicior eft pater, qui lenius aegrotans nihil de
corpore amifit 3 puellus quadrimeftris, cum nigris
cruribus, ante excifionem moritur. Mater, tres
filiae et duo filii feptem crura et quatuor pedes amit-

r^] P^dlof Tranf. Vol. LII. N® 84 et 85.

Ibid, N“ 83 et 98.

\i] Medical Mufeum^ tom. I. p. 442. tom. II. p. 499.

tunt.

[ >25 3

tunt } ex duodecim itaqiie pedibus undecim exci-
dunt aut refcinduntur. Haec eft vera imago mcrbi
Solonienfis.

Defuit eadem caufa, fecale nimirum cornutum j
at non defuit corruptum frumentum, a quo malus
conficiebatur panis, cujus ufus alium hominem in
eumdem nioibum, ledlongeleviorem,conjecit. Quae-
renda ergo caufa morbi in grano, quod erat, obfer-
vante Cl. Wollaston, nigrum et corruptum j cre-
didit autem Mullerus, male quidem, nec forfan
tamen fine aliqua obfervatione, clavum non fine.ufti-
lagine nocuifie.

Cur vero prae caeteris base aegrotavit familia ?

I; In Silefia duae integrae familiae a vivis tolle-
bantur, quibus inerat ergo aliqua proegumena difpo-
fitio nociva.

In Solonia duo fratres prae aliis acerbe morbo
multabantur. - Blaefarum unicus homo aegrotafie vi-
detur. , Aliae obfervationes demonftrant nonnullas
perfonas faciilime gangraena corripi [>^].

2. In Silefia-. morbus infantes praefertim invafit :
juvenes erant aegri Britanni, et mater debilis ex lac^
tatione.,

3. Erant omnes macilenti et valetudinarii, quod
arguit vapidum fanguinem.

4. Obfervatum eft alibi aerem humidum et clau-
fum, carnem porcinam, diaetam ladeam morbi
vires auxiffe, haec omnia in domo Downingiana
adcrant.

5. Non, mode maligno pane, fed maligno vervece,
maligno lardo, malignis pifis, nonnullis protinus noxiisy

[i] ^lefnay de gnngrcsna^ p. 413.

ufa

[ *26 ]

ufa efl Infelix familia : haec omnia fuam folverunt

6. Morbus non fuit contaglofus.

Vale, vir optiine ^ et benigne halce qualefcumque
paginulas accipe.

Laufannae Helvetiorum, 28 die Junii, 1764.

XVIII. Ob fer vat ions for fettling the Propor^
iiony which the Decreafe of Heat bears
to the Height of Situation* ExtraSled
from a Letter of Thomas Heberden,

M. D* F* R. S* to William Heberden,
M*D. F.R.S.

portion as we afcend the mountains here, induced
me to make the following obfervations, with intention
to difcover if there fubfifts any regularity between
the difference of heat and the elevation of fituation.
In order thereto, befides feveral obfervations made at
different times, without any remarkable variation, I
took the opportunity of a journey of fome Englifh
gentlemen in Odober laff, whofe curiofity led them
to afcend the mountain, called here Pico Ruivo, be-
ing the higheft land on this ifland, the perpendicular
height of which above the fea’s furface is, according to
Mr. de la Luc’s method of menfuration by the
barometer and thermometer, 5141 Englifh feet.
Being fupplied by me with the proper inftruments.

fymbolam.

Read J

H E remarkable tranfition from
heat to cold in all feafons in pro-

4

and

[ 127 ]

and their watch adjufted by my regulator, they care-
fully remarked the hour and minute each obferva-
tion was made, which on their return was compared
with the height of the thermometer and barometer
in my ftudy at the time of the obfervation, of
which I had kept an exadl account during the
journey. From which obfervations I have formed
the following table, fuppofing the defcent of the
barometer of an inch for every 90 feet.

Defcent of
Barom.

Elevat, at 90
feet for one
tenth of in,

Defcent of
Therm.

Elevat. correfpond-
ing to each Degree
of Thermometer.

In.

Dec.

Feet.

Degrees'.

Feet.

0.

4

360

2

180

I.

2

1080

5 1

1964

I.

3

1170

6

195

1.

5

1350

9

150

I.

65

1485

10

148,5

3-

75

3375

17

198

A-

2

3780

19

199

5-

I

4590

18

255

I fufpedt the juftnefs of the laft obfervation, it be-
ing made at noon on the fummit of the mountain,
the fun Ihining very hot, and no proper (hade for
the inftruments. ‘ ’

N, B. The thermometers were Fahrenheit’s.

Although the different degrees of heat in different'
places muft depend greatly on the accident of fitu-'
ation, with regard to mountains, valleys, and
different foils, &c. yet there is fo much regularit^^ th
the above obfervations, that, perhaps, Vv’e fliall "not

eiT

[*28]

err much in computing (where the foil and furface
are tolerably uniform) the decreafe of heat (by
Fahrenheit’s thermometer) in the proportion of
one degree for near 1 90 feet of elevation on this
ifland.”

cc

<(

XIX. Account of a Stone voided without
Help from the Bladder of a JVoman at
Bury. Communicated by William Hcber-
den, M,D, F, R. S»

Read Mar. LIZ AB ETH, the wife of Charles

My Coe, a poor labouring man, of the
parlfli of Lawfliall, in Suffolk, aged about 67, having
been feverely afflidfed with fymptoms of the ffone
between 1 1 and 12 years ; her urine continually
draining away with great iinealinefs ; fometimes at-
tended with the moll excruciating pains j and for
tome years unable to lit upon a leat ; on Monday
jith of February, 1765, voided a ffone as de-
fcribed in the Plate.

For two or three days before the ffone came away,
blood was difcharged from the Meatus Urinarius,
particularly a large quantity of fincere blood with-
out Mucus at the time the ffone was voided j at
which time fhe was not in great pain j but after its
cxclufion remarkably eafy. Her urine now paffes
involuntarily without pain } and ffie can fit upon a
feat without uneafinefs.

I

Her

o'

\

%

is

\

<

>■

V

Si

■N

>

Tbdos. TrunsVol. ZV. TAB.11l{b)j.>. y J

^ ^ y n ^

H <vy//Z <r^ /Ac (/foyy/U. ^//, tl-i-

S >-'/*> c/i c.i / Lli^at^e?^

[ 129 ]

Her poverty is fo great, that during this long and? .
painful fcene of fuffering, fhe had no afliftance from
medicine, or art, in any (hape whatever j fo the ex-
clulion of the ftone was wholly the work of nature.

Bury, March 25, J- Steward, Surgeon.

1765. R. Hafted, Apothecary.

Explanation of the Plate.

{hews the flone as indented by prelTure of the
neck of the bladder where appears the nucleus
marked b\ cc, feveral fmall ftriaa leading to thole
larger canals marked ddd^ being the only palfages
by which the urine could get off, which was con-
tinually draining away ; the lower canal appears
corroded by the acrimony of the urine ; c e, two
appendices of frelh calculous matter. This is a
fide view of the ftone.

VoL. LV.

S

XX. A.

['130 ]

XK. A Letter from John Bevis, M. D. to
the Rev, Thomas Birch, D, D. Secretary
to the Royal Society \ cordaming AJirono??ti-
cal Ohjervatio?is^ made at Vienna, hy the
Rev, Father Jofeph Lielganig,

Dear Sir ;

Rcad^ April 25, AT HER Lelfgaiilg, in a very
^ ^ ,1a polite and I'enlible Latin letter,

dated Vienna, April 3, 1765, informs me, that a
correfpondence between himlelf and me had been
recommended to him by Father Bofchowick, who
paid him a vilit in his return from Conftantinople j and
h ather Bofchowick above a year ago fent me a very
high charader of his confrere’s affedion, afTiduity,
and abilities for aftronomical obfervations. You will,
therefore. Sir, be pleafed to lay the inclofcd fett,
which 1 have juft received from him, before the
Royal Society j as they, indeed, appear to me to
have been made with much care and circumfpec-
tion.

By his own account, he was appointed to the Ob-
fervatory of the jefuits College at Vienna towards
the end of 1754; where he found, indeed, a large
ftock of inftruments, but moftly unfiniftied and
imperfed ; that, after fpending a whole year in
getting them fit for ufe, he had difagreeable and un-
avoidable avocations, which kept him fome years
from refuming the care of his beloved Obfervatory j
2 but

[ I3I ]

but that now he finds himfelf in pofTeffion of the
following complete apparatus.

1. Two mural quadrants, each of nine feet ra-
dius, placed north and fouth in the meridian (the
Vienna to the London foot, as loooo to 9646).

2. A fix feet quadrant, fupported by a vertical
axis, and convertible to any azimuth.

3. A, ten feet fed:or, confiruded in P. Bofchowick’s
manner.

4. A four feet quadrant, placed on the azimuth
circle which Tycho Brahe ufed at Prague.

5. A moveable quadrant of 2 4 feet radius, which
he ufed in the menfuration of three degrees on their
meridian, by order of the Emprefs Qj^en, by means
of a feries of triangles, the refult whereof he is calcu-
lating at this time.

6. A tranfit inflrument of 6 4 feet.

Together with feveral fixed telefcopes, a gnomon
14 feet high, micrometers, &c. of all which he in-
tends to publifh a particular defcription, with his
obfervations taken at Vienna reduced and compared
with aflronomical tables. He makes the latitude of
his obfervatory, at the Jefuit’s College, 48° 12'' 35''.

Dear Sir,

Your affedionate,

and mofb obedient fervanri

Clerkenvvell-CIofe,

April 4, 1764.

S 2

J. Be vis,

1764.

1764* Occultatlo Spicze fjg a Luna, Februar. 20.

Temp. Horolog.

Tempos Verum,

h ! tr

0 19 20,1

20 die Febr.

0 19 8,6

21 die

h / //

15 10 13,0

14 51 0,0

16 II, y

56 58,8

16 13 28,7

15 14 16,2

18 26 52,5

18 7 41,1

Eclipfis

Temp, Horolog,

Tempos Verum.

h / n

0 14 57,9

die 17

0 18 45,6

die 18

24 0 8,3

h • //

II 44 45

47 47~

12 14 32,9

57 4L4

15 I5H

58 23,9

16 42*,4

59 50,8

16 54,4

12 0 2,8

Meridies ex altitud. correfpond. O
Meridies

%

Immerfio Spicse in Limb. D lucid.

D Limbus orientalis in Meridiaiio.
Emerfio Spicje ex Limbo obfcur.

^ Ophiuchi in Meridiano. Hujus alti-
tude major erat, quam altitude Limbi
D Auflralis 6' 22", 5.

Mercurius in Barom. 2yd. 10,5!. Parif,
in Therm. Reaumur. + 7,0

12

3 25
6 34
8 15
10 28
14 26

Barometri variatio a die 17 ad 18 erat a
2yd. II 1. ad 2yd. 81.

Thermometri a + 4 ad + 5
Merid. cx alcit. correfpond, G
Merid.

Revolutio Fixarum ex culminationc
Rigel in 7'ubo fixo.

Initium dubium umbrae denfae.
Obfeuratio o dig. 47'.

D Limbus occid. in Meridiano
P cornu praeced. infer, in Merid.

P cornu fequens fuper. in Merid.

P Limbus orientalis in Meridiano.

P cornu fequens altius erat quam
Limb, p eclipfatus ,8' 25".
Grimaldi medium immergitur.
Obfeuratio 3 1 dig.

Pitatus totus.
dig.

4i-

-a

u

a.

ON

o

X

tj:;

&

4

Tern.

Temp. Horolog.

[ 133 ]

h f It

13 47 25,4

Tempus Verum.

h

/

ft

18

27

22

35

24

28

25

35

26

32

26

57

27

5

29

30

31

54

33

31

37

30

38

54

39

29

41

30

42

51

43

40

46

7

48

15

49

25

51

10

54

12

55

37

57

24

59

30

13

10

10

23

50

24

48

30

i9>4

13

37

46

43

4

43

40

45

25

48

6

51

9

52

50

5

% 2*

Fracaftorlus tangitur, feu
mergi.

Fracaftorii medium.
Keppleri medium.

6 dig.

Fracaftorlus totus.

tangitur.

Copernicus totus.

Copernicus

6

incipit im-

1:

Eratofthenes tangitur,

Langrenus tangitur.

Langreni medium.

Langrenus totus.

7 f-

Manilius tangitur.

Manilius totus.

Menelaus et Taruntius tanguntur.
Menelaus totus, et obfcurat. 8 dig.
Promontorium Somni tangitur.

Mare Crifium tangitur.

Proclus.

Obfcuratio maxima, 8 dig. 23'. Dura-
vit fere 12'.

Mare Crifium totum immergitur.
Grimaldi medium emergit.

Grimaldus totus emergit.

in Meridiano. Culminantis D lim-
bus auftralis altior erat quam ^ >6'.

24".

7

n- .

Manilius totus emergit.*

Menelaus totus.

6.

Schikardi medium.

Tempus

Tempus Venim.

h ! "

53 27
56 53
14 o 10

0 55

1 17

2 5

4 52

5 19

6 7

7 21

8 49
8 52

12 40
16 IS
19 28
22 39

25 35
27 16
‘ 29 30

[ 134 ]

Schikardus totus.

5*

Proclus.

4|-

Maris Crifium medium.
Promontorium Somni totum.

4*

Tychonis medium.

Tycho totus.

Taruntius totus.

Promont. acutum.

3-

2|.

2.

2*

Finis umbrse denfc,

Eclipfis

[ I3S ]

Ediplis © , ante et poft Meridiem i Aprills.

Ante Obfervationem Eclipfeos referam Solis et Stellarum in ejus Par-
allelo conftitutarum, culminationes, iis diebus obfervatas. Baro-
metrum i et 3 Aprilis fere ad 27 d. 9I. conftitit ; 2 Aprilis vero
circa Meridiem ad 27 d. lol. Parif. Reaumurianum Therm, often-
dit fere + 7: Procyone vero 3 Aprilis culminante + 8,9.

Temp. Horolog. Teinpus Verum,

I April.

h

ff

0

7

3i>7

3

8

35>7

0

0

24,7

10

10

29>5

23

56

0,8

2

April.

0

8

14,0

10

6

30^5

23

56

0,6

3 April,
o 7 53>i
6 41 37,8

23 58 56,0

O O 0,0

o o 49,0
10 2 2,8

O O 0,0

9 5^ 25>5

O 0 0,0

6 33 50, 4-

31 Martii.
22 21 50

S cornu Auftralius in Meridiano.
©centrum ex altitudibus correfpond.

D cornu Borealius.

d Stella haec Borealior erat quam limb.
]) Auftralis culminans, ii'. 7,3": et
Auftralior, quam cornu ]) Boreum cul-
minans, 6'. 48",!.

Revolutio fixarum a i ad 2 Aprilis.

0 centrum in Meridiano.
d Stella auilralior erat quam limb.
O auftralis culminans, Micrometri
Revolut. 6,/-®-, feu 3'. 47''5°-.
Revolutio fixarum a 2 ad 3 Aprilis.

©centrum in Meridiano.

Procyon. Stella Borealius erat quam 0
limbus fuperior Micrometri Revol.
4,46, feu 2\ 44", 5.

Initium Eclipfeos © . Pro determinanda
quantitate Eclipfis ufus fum Tubo
dioptrico prjeclaro 5 | ped. Microme-
tri Revolutiones 34,14 Diametrum ©
eo die aequabant. Definivi autem
quantitatem obfcurationis ad fingulas
Revolutiones cochleae micometricae, et
inde ad digitos reduxi.

Tempus

Temp. Ver.

1 — 1

H

G^
1 — 1

-

h V //

‘

22 30 4

I dig-

Thermora.Reaumu-

32 2

I 15'

rianum loco con-

34- 0

I 30

fueto, quo radii

36 7

I 45

folares non per-

38 14

2 0

tingunt, pofitum.

40 16

15

durante Eclipfi.

42 2

30

vix ultra f grad.

43 56

45

mutationemfubiit.

46 12

3 0

Therm, vero ejuf-

48 23

15

modi Soli objec-

50 28

30

turn oftendit.

52 22

45

54 23

4 0

56 31

15

58 41

30

+ 18,0

23 0 54

45

3 I

5 0

5 14

15

7 25

30

9 40

45

11 46

6 0

17,8

13 59

*5

16 II

30

18 36

45

21 15

7 0

23 47

15

16,2

26 7

30

28 39

45

31 25

8 0

15,2

34 20

*5

37 15

30

40 10

45

43 6

9 0

Sol ecliplatus imminet Meridiano

13’^

Temp.

[

137 ]

Temp. Ver.

I Aprilis.

h / n

d /

0 27 24

6 30

14.7

29 41

15

32 2

0

16, s

34 14

5 45

36 27

30

38 29

15

18,0

40 45

6

43 6

4 45

44 58

30

47 6

15

■ 49 17

0

18,5

51 31

3 45

53 37

30

55 53

15

58 10

0

59 58

2 45

I I 58

30

19,0

3 50

15

6 38

0

8 38

I 45

10 41

30

21,2

12 42

15

14 25

0

21,5

23 13 Fuiis Edipfis tubo dioptrlco infigni
Euftachii Divini, pedum fere 12.

VoL. LV,

T

15 Aprilis.

[ 138 ]

15 Aprilis.

Occulfatio Spicae 1^ a b

Tempus Verom,

II 21 41,7 f Immerlio Spic^ in Limbum >
lucidiim tuba dioptrico Diviniano
12 pedum. Stellam tempore
Emerfionls non vidi nifi jam a
5 Limjbo diftantem, turn ob nu-
bes, auae intercefferant, turn ob
nimiam Lun^ fere plqnae lucem.

Aliae ^ Occultatlones yienoae obfervatac.

1736, Augufti

1736, Pdfcbr.

1737, Martii

1738, Odiiobr.

1756, De^emh.

1757, Dec^emb^
1700, Martii
1762, Febjruar.
1762V Martii

.2

22

8

2

5

12

29

2

2

Occultatio

a b.
a bl
a bl

a ^
a bl

€ di

» n?

y
9

N. B. B hie adferiptis diebus etiam in Tranfitu per Meridianum
obfervata eft. Stellarum, O et B altitudo in Tranfitu per Me-
ridianum femper obfervatur in Quadrante murali 9 pedum,
/lift aliud Inftrumentum indicetur.

XXI. Jri

C 139 ]

XXL An Account of the Cafe of a fuppofed
Hydrophobia : In a Letter to the Rev,
Thomas Birch, D, D, Secretary to the
R(yal Society^ from the Right Honourable
James Rarl of Morton, Prefdent of the
Royal Society,

Brook-Street, Wednefday, April 24, 1765;

Rev. Sir ;

HAV I N G read a remarkable account in the
Public Advertifer of the 2 2d of June, 1764,
that a perfon, who, ih confequence of the bite of a
mad dog, was affedted with the Hydrophobia, had been
cured at Padua by draughts of vinegar, I was willing
to get the bed; information of the true ftate of the
fadl. Accordingly I wrote to my acquaintance Ge-
neral Gramme, commander in chief of the Venetian
forces, defiring he would fend me an accurate hiftory
of this extraordinary cure ; and fome time ago f
received from him the inclofed account \ which, if
you think proper, you may read before the Society.
The account in the Public Advertifer, being fo very
particular and circumdantial, induced me at firfl to

T 2 believe

[ HO ]

believe it might be well founded ; in which cafe, fo
valuable a difcovery ought to have been publilhed
every where : but, as it turns out to be altogether a
fallacy, the public ought equally to be undeceived.

I am,

4

Rev. Sir,

Your v^ry humble fervant,

Morton.

Venice, December 8, 1764.

Read April 25, | ^ H E hiftory of the Hydrophobia

1765. cured by vinegar is equivocal, or

perhaps altogether a miftakej and the procefs was
what follows.

Dr. Bertolh, phylician, and now profelTor in the
univerfity of Padua, came to Venice in the laft
fpring, and brought an account to Dr. Reghellini,
that three hydrophobous perfons, all bit by the fame
mad dog, had been treated in the hofpital at Padua,
two of whom died, and only one efcaped, and that
the perfon, who furvived, was cured by Dr. Leonilfi
with vinegar, which he was made to iwallow every
three hours in dofes of about four ounces at a time.
This cure, performed by Dr. Leonifia, was fuggefted
to him by a dudent of phylic at Udine, who oblerved,
in the Friuli, a hydrophobous perfon, who was cured

by

[ I4I ]

by means of a mlftake, that happened in the family,
by giving him vinegar to drink inftead of water j[^].

Dr. Reghellini, willing to be thoroughly fatisiied,
whether this acceptable difcovery was flridtly true,
did immediately write to a friend of his, a phyfician
at Padua, ftating all the circumdances, which had
been related to him by Dr. Bertoffi, and defiring to
know, if the fa(5t really was as it had been dated. His
friend, the phyfician, gave him for anfwer, that the
thing was true.

Dr. Reghellini thereupon communicated the cafe
to the phyficians of the hofpital of Florence and
Pifa, and defired them to make trial of it, the fird
opportunity that diould offer, and acquaint him with
the fuccefs. He likewife communicated it to his
other friends, amongd v>^hich was Dr. Turton, an
Englifli phyfician then at Venice; and to Dr. de la
Fontaine, a phyfician, who attended Lord Spencer \_h'].

Dr. Reghellini judged, that fo uncommon an event
ought to be publidied with all its circumdances
and having in his poffefiion the hidory of eight and
twenty hydrophobous perfons, though in. different
manners, and treated by different phyficians, fifteen
of whom were afterwards opened, and the bodies
carefully examined, he thought from, thence he.
might compofe a rational and ufeful tra(ff. Therefore
he went to Padua, to have a perfonal interview with.
Count Leonifia, the phyfician; but in this con-
ference he difcovered, that the man, who was faid to

[a] Dr. Bertoffi (aid in the Friuli. Count LeonifTa fays in
Lombardy. Perhaps fome other perfon may have faid in Turin.

[b\ Probably the account publifhed in England may have
come from one of thefe two gentlemen.

have

[ 142 ]

have been cured with the ufe of vinegar, really never
had the hydrophobia, although he had been alTured,
that Dr. Bertoffi faw him in the hydrophobous ftate.
That man, it was true, did receive a very flight and
fuperficial fcratch upon his cheek from the fame
dog, who bit the other two perfons, who became
hydrophobous, and afterwards died ; but the perfon,
of whom the account was publilhed, about the
ufeful difcovery of a cure by vinegar, was in reality
never arrived to the flate of the hydrophobia ; that
is to fay, to fuch a degree of the malady, as mofl;
frequently follows the bite of a mad dog, and which,
after fome weeks, difcovers itfelf by an uneafinefs in
attempting to drink ; and after drinking, by a fe-
ver, delirium, convulfions, vomiting, fweating, and
death, within the fifth, and fometimes within the
fourth day.

Dr. Reghellini, having thus found, that the account
firfl: given him, and the confirmation of it from his
friend at Padua, were doubtful, or rather a mifap-
prehenfion, wrote again to Florence and Pifa, re-
tracing his former account, and relating the faC, as
upon a more ftriC examination he had found it truly
to be, and which is exaCly agreeable to the account
here inclofed.

XXII. Tu'O

[ I4S ]

XXII. Iasoo "Theorems^ hy Edward Waring,
M. A. Lucafian Profejfor of Mathema-
tics in the Univerfity of Cambridge, and
jF. R. S, ^ Letter to Charles Morton,
M. £). Sec. R. S.

T H E O R E M A I.

_ FiG4J r a I.

Read April 25, V N data Ellipfi- inrcribantur duo (^)
^ Laterum Polygona abcde^ &c. et
^qr st^ &c. ad Pundta refpedtiva e, &c.

p.i ^7 ti &c. dueantur Tangentes A B, B C,

CD, D E, &c. et P Q, QJl, R S, ST, &c.
et fint

^ ab'^ — 4S. c bGy <^b cQ—^dcY>y ^ cdT>
z=i^edEy &c. et ^ y Q — r ^ R,

^ r s 'S ^ t sTy^ et Tic deineeps.

Et erit Summa Laterum

I 0 b *~|~*^ c 'A^cd ■ ^d C--^^ 6cc. ■ 6cc».

Fl GU R A £.

Cor. Ducatur in Ellipd Polygonum ahcde See.
(n) Laterum Methodo fupra tradita ; inferibatur etiam
aliud Polygonum ah klm &c. [n) Laterum quovis

alto

3

[ 144 ]

alio Modo, cujus unus Angulus ponitur ad Pundum
(a), et Summa a 6 -\-if c d e 6cc. major
cil quani Summa a h -\- h k k I -\-l m 6cc.

T H E O R E M A II.

Tab. IV. F I G u R A i.

Defcribantur circa datam Ellipfim duo («) La-
terum Polygona ABCDE 6cc. et PQRST &c.
quorum Pundta Contadtuum refpedlive funt
&c. &c.

Et fint

Tang. beca. Comp. ^ aBi^: Tan. Seca. Comp.
^ c C :: 6 C : ^ B, et

Tang. Seca. Comp. ^^cCb : 'I'an. beca. Comp.
^ c D d :: c D : c C, et

Tang, q- Seca. Comp. ^ cD d : Tan. -fSeca.Comp.
^ eB d B d : aD &c.

Et fic

Tang, q- Seca. Comp, /> Q 5' : Tan. q- Seca. Comp.

qKr : : y R : y et^

l ang. q- Seca. Comp. ^^R r: Tan. q- Seca. Comp,
i S r : : S r : r R, et

Tang, q- Seca. Comp, 5 S r : 1 an. q- beca. Comp,
.t:^ ^ T j : : T j i S, et lie deinceps.

Et erit Summa Laterum

ABq-BCq-CDq-DEq-'&c. =rP Q^q-’
QJl q- R S -p S T q- &c.

Figura

(

1

i

[ H5 ]

p

Figura 3.

Cor. Defcribatur circa Ellipfim Polygonum («)
Laterum ABODE, &c. Methodo, quae prius data
fuit; Defcribatur etiam circa Ellipfim aliud Polygo-
num G Hi^L M, &c. (72) Laterum quavis alia Me-
thodo, cujus unum Pundum Contadus (a) eft
Pundum Contadus Polygoni A B C D E, &c,

Et Summa AB r|-)BC q- CD q- DE q- &c.
minor erit quam Summa GH q-HKq-KL-}-
L M q- &c.

• • Confimiles Proprietates affirmari pofiunt ^de Poly-
gonis Hyperbolas defcriptis, &c.

VoL. LV.

U

XXIII. A

[ ]

XXIII. A Dijfertation on the Nature of Eva-
poration and fever al Fhcenomena of Air^
Water ^ and boiling Liquors : In a Let-
ter to the Rev, Charles Dodgfon, Z). D,
F, R, S, from the Rev, Hugh Hamilton,
D. D, F. R. S, Profejfor of Natia al
Philofophy in the Univerfety ^Dublin.

Dear Sir ;

Read May 1 6, 'W' Here fend you, according to promife,
X thoughts on the nature of eva-
poration, the afccnt of watery vapours, and fome
other phaenomena of the atmofphere, in explaining
which I have employed a principle that, as far as I
can find, is different from what has been hitherto ufed
on this occafion, hoping thereby to avoid thofe objec-
ions, which fome late writers have made to the former
accounts, that have been given us of thefe phaenome-
na. For in all the accounts I have met with, fire or
heat, and rarefa(ftion, by which watery vapours are
fuppofed to become fpecifically lighter than air, are
made to be the principal, if not, the only caufes of
their afcent into the atmofphere. Dodlor Nieuwentyt,
and fome others, fuppofed that the particles of fire, by
adhering to thofe of water, make up molecula?, or
fmall bodies, fpecifically lighter than air. And Dr.
Halley thought, that by the adtion of heat, the par-
ticles of water are formed into hollow fpherules filled
with a finer air highly rarefied, fo as to become fpc-
cifically lighter than the external air. This lafi:

was

[ 147 ]

was the opinion moft commonly received, as Do(5lor
Defaguliers tells us in his differtation on this fub-
je(fl, publiflied, in the Philofophical Tranfaitions, in
tlie year 1729, in which he examines and refutes
thefe two former opinions, and endeavours to eflablifli
his own. He afcribes the afcent of aqueous vapours
to their being turned into an elaftic fteam, and al-
ways rarefied more than the air is, by the degrees
of heat, to which bodies are ufually fubjedl in the
different feafons of the year.

This opinion, I find, has been as ill received by
fubfequent writers as the former ones. Mr. Clare,
in his Treatife on the Motion of Fluids, has brought
many objedlions againfl it ; as Mr. Rowning has
alfb done in his Syffem of Natural Philofophy not
long fince publifbed ; who fays, that the caufe of
the afcent of vapours has been much difputed, but
not yet fettled, by philofophers, and owns that he
cannot think of any true principle of philofophy,
upon which it may be accounted for.

I fhall not now repeat the objedlions made by
thofe gentlemen ; but muft beg leave to add only
the two following; which, among many others
that might ffill be urged, they have not taken
notice of.

Firfl ; If heat was the only caufe of evaporation,
water in a clofe warm room would evaporate fafter
than when expofed in a colder place where there is
a conflant current of air ; which is contrary to ex-
perience.

Secondly ; The evaporation of water is fo far
from depending upon its being rarefied by heat, that
it is carried on even whilft water is condenfed by the

U 2 coldnefs

[ 148 J

coldnefs of the air ; for water is gradually con-
denfed by cold till the moment it freezes, and fince
it evaporates even when frozen into hard ice, if
muft alfo evaporate in all the lelTer degrees of cold.
Now Mr. Boyle having counterpoifed a piece of ice
in a fcale, hung it out in afrofty night, and found next
morning that it had loft confiderably of its weight by
evaporation. Who (fays he) would have thought
that fo extremely hard and cold a body would evapo-
rate fo faft in the clear air of a freezing night?’' And
fince- that time others have obferved the fame thing;
which fadt feems to be an unanfwerable objedfion to all
the accounts in which rarefadtion by heat is.made to be
the chief, if not the only caufe of evaporation ; and,
therefore, we muft have recourfe to fome other
principle to affift us in accounting for this plneno-
menon.

As the author of nature does not employ in his
works^ a greater variety of caufes than is abfolutely
neceftary; it is the bufinefs of natural philofophy to
reduce as many phaenomena as may be to fome ge-
neral well known caufe ; and this is to be done by
comparing the phasnbmena together in their feveral
circumftances, in which, if they are found to agree,
they are then to be confidered as effedls of the lame
kind, and aferibed to the fame caufe. By which means
the caufes, whofe exiftence is already proved, will
be rendered more general, and our knowledge more
extenlive. Now as the fufpenlion of the particles
of water in air, of fait in the waters of the ocean,
and of other heavy bodies in the fluids that diflblve
them, feem to be pha:nomena of the fame kind,
we might reafonably fuppofe that they arife from

the

C M9 ]

the fame caufe ; and that what we call evapora-
tion is no more than a gradual folution of water in
air. But that I may not propofe this meerly as an
hypothefis, I Ihall endeavour to prove the truth
of it, by confdcring the nature of folution in ge-
neral, and comparing its properties and effedts
with thofe of evaporation. By folution we un-
derftand, The uniting fo intimately the particles of a
body with thofe of a fluids that the whole f^ll appear
an homogeneous mafs, as tranfparent as the fluid was be^
fore Juch union, and Jhall fo continue till feme external
caufe produces a change. The nature of folution has
been explained by the writers on chymiftry in this
manner. When the particles of any body furrounded
by a fluid are lefs flrongly attracted by each other
than by the fluid, they feparate from each other, and
join themfelves to thofe of the fluid, and remain
fufpended therein.

Thus various falts are diflblved in water, elTential
oyls are diflblved in Ipirits of wine, gold in aqua
regia, mercury, filver, and other metals, in other
acid fpirits.

And indeed it feems to be with great appearance
of reafon, that the attradlion between the minute par-
ticles of bodies (of which we have fo many other
inftances) is afiigned as the caufe of that union be-
tween them, which we experience in folutions.
The chief properties of which I fhall now mention,
fo far as may be neceffary for the purpofe to which
I mean to apply them.

In moft cafes a diflblving fluid, or menflruum, as
the chymills call it, will diflblve or take up only a
certain proportion of the body immerfed.i and if
then any more of the fame body be added, it will

precipitate

[ 15° ]

precipitate or fall to the bottom, and then the fluid
is faid to be faturated with the body It has diffolved ;
yet a fluid, which is faturated with one body, may
afterwards diffolve others of different kinds, and keep
all their particles fufpended together.

When any menflruum has entirely diffolved a body,
it will continue as tranfparent as it was before. The
caufe of which may be afligned from what Sir Ifaac
Newton difcovered by experiments} that the parti-
cles of bodies muft be of a certain fize, or bignefs,'
to caufe any refledlion or refradion of the rays of
light at their furfaces. From whence he gives the
reafon why fome bodies are opake, and others
tranfparent ; and he alfo obferves, that the mofl:
opake bodies, fuch as metals, being diffolved in an
acid menflruum, and thereby reduced to their ulti-
mate and fmallefl particles, do not take away the
tranfparency of the menflruum.

Hence we may always know how to diflinguifli a
folution from a mixture ; for if a body be reduced
to powder, and thrown into a fluid that will diffolve
it, and they are then fliaken fuddenly together, the
fluid will continue fomewhat opake till the folution
be effeded, or till what remains undiffolved falls to
the bottom. For in this cafe the particles are not at
firfl reduced to their fmallefl fize, as they are always
in a folution. I think, therefore, we may confider
the tranfparency of an heterogeneous fluid (or one
that contains in it particles of another body) as the
criterion of a true folution, and where that is want-
ing, it is only a mixture, as when water and air ap-
pear together in froth, or in a cloud, or a thick mifl,
it is only a mixture of thofe bodies, and not a folution
of either.

This

[ IS* 1

Thus much being premifed of the nature of folutions
in general} I proceed to the proof of what 1 propofed ;
and in order to this, I fliall firft (hew, that there is a
mutual attradlion between water and air, the fame that
we obferve between the particles of any two bodies, one
of which dilTolves the other. I (hall then compare,
in feveral inftances, the properties and effedls of com-
mon folutions, with thofe of evaporation, that, from
the exadl refemblance between thefe two phaeno-
mena, it may appear that they are natural ope-
rations, or cfFedls of a like kind, and therefore to be
explained upon the fame principle, or afcribed to
the fame caufe. From thence I (hall (hew how
the afcent of vapours, and feveral other phaenome-
na of the atmofphere, may be accounted for. And
laftly, I (hall add fomething on the riling of (learn
from boiling liquors, and (hew wherein it differs
from common evaporation.

lam firft to prove, that there is really an attrac-
tive force between the particles of air and water. It
is well known that all waters contain a conliderable
quantity of air that retains its elafticity, by means of
which it may be feparated from the water by boiling,
and including it in an exhaufted receiver. And Dr.
Bocrhaave, in his Elements of Chymiftry, has (hewn,
by an elegant experiment, that air extricated from
water by boiling, and reftored to its common (late,
will occupy a fpace greater than that poffelTed by the
water in which it was contained. Now fince it is
allowed, that the particles of fo heavy a body as gold
are fufpended in aqua regia by their attradlion to-
wards the particles of that fluid, it feems reafon-
able to fuppofe, that fo light and elaftic a body as
air muft be retained under water by a like force, with-

3

[ *52 ]

out which It would always afcend to -the Turface, and
cfcape. But that there is really fuch an attradliye
force between air and water, the learned and inge-
nious gentleman lafl mentioned has fully proved by
the following experiment.

Let an oil flalk be filled almofl: full with water,
deprived of its air as much as may be, let the mouth
of it be then flopped until the neck be immerfed in
a vefTel of water, a bubble of air will then afcend
into the upper part of the flafk. When things have
flood in this way for fome days, the water will be
found to have abforbed the whole bubble of air (if
it was not too large) and intirely filled .the flafk ; but
if the bubble was too large, part of it will be left,
for the water after fome time will abforb no more
air, being then fufficiently faturated with it. It is
obfervable that a part of the included air enters pretty
quickly into the water at firfl, but what remains af-
terwards makes its way in but very flowly. This ex-
periment fhews that water, when deprived of its air,
will again draw the air gradually into its pores, juft
in the fame manner that a lump of dry fiigar will
draw up water into its pores, which will afcend pretty
quickly at firft, but very flowly after fome time.
We have reafon, therefore, to conclude that there is
the fame kind of attradion between air and water,
that there is between water and ^ny dry porous body
that will imbibe it.

As water contains a confiderable quantity of air,,
fo does air contain a good deal of water, even wlien
we think it quite pure and dry, as appears from the
moiflure drawn from it by dry fait of tartar, in fuch
quantity as to make the fait become intirely fluid.

Now

[ 153 ]

Nowfincethe air Is an heterogeneous fluid, containing
in it particles of another body, and yet retaining a
perfed: tranfparency, which is the criterion of a true
ibiution in other cafes, why fliould we not infer from
analogy, that in this cafe alfo it indicates a true folution
of water in air ? efpecially when we confider that
there are hardly any two fluids that may not, by
themfelves, or by the means of fome third body, be
fo thoroughly incorporated, that one of them may
be properly faid to be diflblved in the other. But
the truth of this will be further confirmed, by com-
- paring the properties of common folutions with thofe
of evaporation j which I fliall now do in feveral
inftances.

Firftj when a body is immerfed in a fluid that
diflblves it ; for inftance, a lump of fait in water ; we
fee the fait foon begin to diflblve and impregnate with
its particles the water that furrounds it, which will
then appear thick and loaded ; and if the water be
at refl, the folution will proceed very flowly; but if it
be ftirred about, the fait will foon be intirely diflblved.
How exadlly does this correfpond with what Dr.
Halley remarked in an experiment made on the eva-
poration of water in a clofe room ? Phil. Tranf.
N® 192. “ The fame obfervations (fays he) do

likewife fhew an odd quality in the vapours of wa-
“ ter, which is that of adhering to the furface that
“ exhales them, which they clothe, as it were,
“ with a fleece of vapourous air, which once in-
vefting it, the vapour rifes afterwards in much lefs
** quantity.” Here we fee, that the air, which lay
at reft over the water, appeared thick, and loaded
with aqueous particles 3 and then the evaporation
• VoL. LV. X proceeded

i *54 ]

proceeded very flowly, juft as the water that lies
about the fait appears thick and loaded, and while
it continues at reft, the fait is diftblved very flowly.
He alfo obferves on the fame occaiion that evapo-
ration is vaftly promoted by a current of frelh air
pafling over the exhaling furface j and this I have
no doubt happens for the fame reafon that folution is
greatly promoted by agitation, which continually
brings frefti particles of the fluid into contact with
the body, it diflblves, in the place of thofe that have
been already faturated.

Secondly ; into a glafs of clear cold water throw
a lump of any kind of fait which is foluble in it,,
and when it has ftood a little time, fhake the glafs,..
or ftir the water gently with a wire, and the water
which is faturated with the fait will rife up among
the reft, of the water in curled wreaths, or long ftriae,
which will render the water fomewhat opake,
caufing it to refrad; in different directions the light
of an object feen through it, and it will make the
object appear to have a tremulous motion, and this
will continue until all , parts of the. water are equally
impregnated with the fait, and then its tranfparency
will be reftored. As the parts of the water, which,
are impregnated with the fait, are of different den-
ftties from the reft, while they are mixing together
they muft occafion thofe refraCtions, and this appa-
rent tremulous motion, which will ceafe as foon as all
the water becomes of the fame denfity. The very
fame appearances will attend the mixing together of
any two fluids of different denflties,, and.wich will,
thoroughly incorporate with each other.

In

[ »5S ]

In like manner when fmoak or fleam ilTuing from
the pipe of a boiling veffel firft rifes into the air, it
appears in curled wreaths, and renders the air opake,
but as foon as it is intirely difperfed, the tranfparency
is reftored. Thus alfo in a calm hot fun-fhine day,
when we look along a moift piece of ground, the
air, and any objedt feen through it, appears to have a
tremulous motion like that which we obferve in an
objedt feen through any two fluids that are mixing
together.

Now as the vapours rife here in great abundance,
and the air has but little motion, thofe parts of it
that are much impregnated with the aqueous parti-
cles are mixed gradually with the air that is drier
and of a different denlity, which will occaflon re-
fradlions of the light, and that apparent tremulous
motion jufl: now mentioned. And in this cafe the
folution of water in air (if I may yet call it fo) is
carried on in a manner viflble to the eye, as it is in
other fluids. The fame tremulous undulating mo-
tion is more obfervable when we look in warm wea-
ther through a telefcope, which magnifies the va-
pours floating in the air j and from this kind of re-
fraftion the twinkling of the flats feems to arife,
with this difference only, that the watery refradling
particles in the day time are pafling into a flate of
folution, wherea-s the vapours already diffolved are, by
the cold of the night, beginning to precipitate and
return into particles large enough to caufe refradlions
in the light of the flars.

Thirdly ; Heat promotes, and cold in fome mea-
fure flops, or checks, both folution and evaporation ;
very hot water will diflblve fait fooner, and in a greater

X 2 quantity

[ 156 ]

quantity than cold water j and if a ftrong folution"of
lalt be made in hot water, the water, when cold, will
let go fome of the fait before diffolved, which will
fall to the bottom in fmall particles, or flaoot into
cryftals. Juft fo will water evaporate fafter in warm
than in cold air 3 and the aqueous vapours, fufpended
in the air during the heat of the day, fall down at
night, and form themfelves into drops of dew ; or, if
the night be very cold, appear next morning in a
hoar~fro(i. And thus, if in a hot day, a bottle be
filled with any very cold liquor, and expofed to the
air, which to us feems very dry, a dew will be foon
formed on the outfide of the bottle j for the air about
it, becoming cold, will let go part of its moifture,
which will be attracted to the furface of the s;lafs.
And, for the fame reafon, a dew is formed on the
in fide of the windows of a warm room, which on
their outfide are expofed to thecold.air*. And hence
vve may obferve, that, as there cannot be fb conti-
nual and copious an evaporation in cold weather, the
air will then be generally clearer than it is in hot
w’eather.

Heat feems to promote folution, becaufe it expands
bodies, and thereby enlarges their pores, and leflens
the cohefive attraiftion of their particles, fo that a
body when hot will more eafily admit a diftblving
fluid into its pores, and its particles not cohering to-
gether fo ftrongly, as when cold, will more readily
quit each other, and unite themfelves to the particles
of the fluid by which they are attracted j and for the
fame reafon heat will alfo promote the evaporation of
fluids.. ~

But

[ ^57 J

But fourthly j The quantity of a body diUblved,
and of a fluid evaporated, in a given time, depends
(ceteris paribus) on its quantity of furface. Thus a
body reduced to powder is fooner diflblved than
when it is in a folid form. And thus fmoak, or
fleam, which is water, reduced to very fmall parti-
cles by heat, is much fooner difperfed, and incorpo-^
rated with air, than water in its ufual form.

Fifthly} Chy mills obferve, that when fea fait, fal^
ammoniac, or nitre, is diflblved in water, or eflbn-
tial oyls in fpirit of wine, fome degree of cold is
produced in the immediate a£l of folution ; and the
quicker the folution, the greater is the cold. And <
by diflblving pounded ice, or rather fnow, (whofe
particles have a greater furface) in fpirit of nitre, a
degree of cold has been produced fo great as to freeze
quick-filver. Gold is likewife produced in the adt
of evaporation; for if fpiiit* of wine, or aether,
having the fame temperature with the air, be rubbed
lightly with a feather over the ball of a thermome-
ter, it will fink as the fpirits evaporate, and the
quicker they evaporate, the fafter will the thermo--
meter fink. And the fame, thing wiir happen if
water be ufed inftead of fpirits, . provided its evapo-
ration be promoted by a flrong current of air. And .
thus have. I leen ice produced meerly by repeated
evaporations of aether.

This lafl: obfervation . fliew& a very remarkable
agreement between the natures of folution and eva-
poration. How the cold is produced in either cafe .
I cannot pretend to fay ; but I. mufl beg leave juft
to apply this fadl to account for a thing which I
believe moft people have taken notice of.

. < If.

[ ^58 ]

If we rub Hungary water, or any other volatile
fpirit, over our hand, it will feel much colder than
water, though they be both of the fame tempera-
ture, and will both feel equally cold if we dip our
finger into each. The reafon of which is, that the
fpirit evaporating much quicker than the water, pro-
duces thereby a greater degree of cold ; and fo
aether, if it be applied in the fame way, will feel
colder than any other fpirit on account of its more
fudden evaporation. •

Sixthly ; It is known that redtified fpirit of wine,
when well purged of air, will imbibe a large bub-
ble of air, in a much fliorter time, than water will
do j and I have myfelf experienced the truth of this,
which fhews that there is a ftronger attradlion or
affinity,- as the chymifts call it, between fpirit of
wine and air, than between water and air j and fince
the fpirit evaporates much fafter than the water, I
think we may conclude from hence, that the eva-
poration of fluids arifes from an attradlive force be-
tween their particles and thole of air *.

* As water and fpirit of wine, are in no degree vifcid, they
may evaporate in proportion to the attraftion between them and
air. But the cafe is very different in fuch fluids as are vifcid ;
for though I found that oil of olives, when purged of air, will
imbibe a bubble of air almoft as foon as water does, yet the
evaporation of the oil is hardly (if at all) fenfible in a very long
time. The reafon of which muft be, that the attraction be-
tween air and the oil, is not able to overcome the tenacity of
its particles, and feparate them from each other, though it is
fufficient to draw into the oil particles of air, which have no
attraction to each other, juft as a fponge draws in water, with-
out having its particles feparated by the attraction of the
water.

Seventhly ;

C 159 ],

Seventhly ; If into any menflruum v^re throw a
body, which it diffolves, and afterwards add another,
to which the menftruum has a greater affinity than
it has to the firft, it will diffiolve the fecond body,
and let go the firft, which will be precipitated and
fall to the bottom. In like manner, if to well rec-
tified fpirit of wine, we add an equal quantity of
clear rain, or river water, thefe fluids (which incor-
porate fo readily) having a greater affinity to each
other than to the air they contain, will let go ai
great part of the air, which will rife to the top, or
ftick in fmall bubbles to the bottom and fides of the
veftel ; from whence I infer, that air is contained in
thefe fluids in the fame manner that the particles of a
body are contained in a menftruum that diflblves it ; ,
and, therefore, that the air imbibed by thefe fluids, is pro-
perly fpeaking, diflblved in them, and confequently
that any fluid which evaporates, or is imbibed by the
air, is alfo, properly fpeaking, diflblved in air. And
upon this principle we may fay, that water is drawn
out of the air, by dry fait of tartar, from its having
a greater affinity to that fait than to the air.

1 ihould not have been fo tedious, in comparing,
together the natures of folution and evaporation, in .
fo many inftancos, but that it gave me an opportu-
nity, at the fame time, of explaining fome of the.
phenomena that 1 at firft intended to confider ; ,
which explanations, I believe, will be admitted, if;
li am right in the mean point, I have endeavoured ;
to prove. And really when we confider how exactly
folution and evaporation agree in their feveral ap-
pearances, properties, and effedts, I think we may
be convinced that they are natural operations of

[ i6o 3

the fame kind, and that what we call evaporation Is
nothing more than a gradual folution of water in
air, produced and promoted by the fame means (to
wit) attraction, heat, and motion, by which other
folutions are effected.

I ffiall now endeavour to account for feveral ph^e-
nomena of the atmofphere upon this principle, which
will be ftill further confirmed, if it be found to
anfwer the purpofe to which it is applied.

The lowed; part of the air being prelfed by the
weight of the atmofphere againfi: the lurface of the
water, and continually rubbing upon it by its motion,
has thereby an opportunity of attracting and diffolv-
ing thofe particles with which it is in contaCt, and
feparating them from the reft of the water. And
fince the caufe of folution, in this cafe, is the ftronger
attraction of the particles of water towards air, than
towards each other, thofe that are already diflblved,
and taken up, will be ftill further raifed by the at-
traction of the dry air that lies over them, and thus will
diffufe themfelves, rifing gradually higher and higher,
and thereby leave the lowed; air not fo much fatu-
rated, but that it will ftill be able to didblve, and
take up frefti particles of water. And thus ice, or
fnow, will evaporate as well as water, its particles
being attracted and diffolved by the air, which is
ftrongly preffed againft its furface, for though heat
promotes both folution and evaporation, yet we do
not find that in either cafe any fenfible degree of it
is abfolutely neceffary *,

* Water, by freezing, is deprived of its air, which v/e fee
-gathered into bubbles through the ice, therefore the fubHance
of the ice, being deprived of air, will attract the external air

In

[ i6i ]

In this manner will aqueous vapours afcend llowly
into the atmofphere, even when we fuppofe the air
almoft at reft, for I believe it is never perfedtly fo:
but the folution of water in air, and the afcent of
vapours, is greatly promoted by the motion of the
w'inds, which bring frefh and drier air into the place
of that which may be already faturated and loaded
with moifture, carrying it together with its moifturc
into the higher parts of the atmofphere, and difperfing
it into all quarters. If we fliould now fuppofe the at-^
mofphere to remain always of the fame temperature
as to heat and cold, and to have always the
fame denfity; when it was once faturated with
water, all evaporation would ceafe, and the va-
pours already raifed would always remain fulpend-
ed ; for a fluid, while it continues of the fame tem-
perature and denfity, will never let go the particles
of a body that it has diflblved. We muft, there-
fore, confider what are the caufes which occafion
the air fometimes to part with the water it has dil-
folved, and which thereby keep up a continual cir-
culation of vapours. And thefe I fliall Ihew to be
the frequent vicifiitudes of heat and cold, conden-
fation, and rarefadlion, to which the atmofphere is
fubjedt.

As to the effedis of heat and cold, I have already
ftiewn that the former promotes, and the latter checks,
or in fome meafure hinders evaporation, as well as

more ftrongly than common water does, which is faturated with
air. And, on this account, I fliould think it probable that ice,
notwithftanding its hardnefs, will evaporate as faft as common
water.

VoL. LV.

Y

■other

[^62]

other folutlons ; of which I gave an inflance in the
vapours that are fufpended in the heat of the day,
and by the cold of the night are precipitated, and
fuffered to coalefce into drops of dew. From the
fnow that lies fo long on the tops of mountains, and
from the experience of thofe who have palTed over
them, we find that the higher parts of the atmofphere
are much colder than the lower. Now, though
vapours are firfi: raifed, and abound moftin the lower
parts of the atmofphere, yet they cannot there form
themfelves into clouds, becaufe the heat that helped
to difiblve them helps allb to keep them difiblved.
But when they are carried by the winds into the
higher parts, where the fame heat is wanting, the
cold air will not be able to keep difiblved all that
are carried up, but mufi: fufibr fome of them to
coalefce into fmall particles, which (lightly atcradting
each other, and- being intermixed with- air, will form
clouds^ having the very fame appearance with fleam,
or fmoak, which alfo confifts of fmall particles of
water, mixed with air, and not yet difiblved in it.
Thefe clouds, when firfi: formed, will remain fuf-
pended, though they confifi of water as well as air,
bccaufe the weight of their particles will not be able
to overcome the refifiance they mufi meet with in de-
fcending through the air. For when bodies are di-
minifiied, their quantities- of matter, to which their
weights^ are proportional, decreafe fafier, or ifi' a
greater ratio, than their furfaces, to which the re-
fifiance they meet with is proportional j and, there-
fore, in very fmall particles, this refifiance may be-
come greater than their weight. The different heights
at which clouds arc formed, depend on the quan-
tity

2

/

[163]

tity of vapours carried up, and the degrees of heat
in the upper parts of the atmofphere ; for the vapours
will always afcend, till they meet with air fo cold, or
fo thin, that it is not able to keep didolved all that
comes up; hence clouds are generally higher in
fummer than in winter. When clouds are much
increafed^ by a continued addition of vapours, and
their particles are driven clofe together by the force
of the winds, they will run into drops heavy enough
to fall down in rain ; fometimes the clouds arc fro-
zen before their particles are gathered into drops, and
then fmall pieces of them, being condenfed and
made heavier by the cold, fall down in thin flakes
oi f now y which appear to be fragments of a frozen
cloud. But if the particles be formed into drops
before they are frozen, they fall down in hail-Jiones.

When the air is replete with vapours, and a cold
bieezc fprings up, which it often does from the fea,
the folution^ of thefe vapours is checked, and clouds
are formed in the lower parts of the atmofphere, and
compofe what we call a 7nijl or Jog, This generally
happens in a cold morning; but when the fun has
been up for fome time, the warm air again dilTolves
thofe watery particles, and it frequently clears up.

In a hot fummer’s day, the air lying over wet
marfliy ground, is copioufly faturated with aqueous
Vapours ; but the air growing cooler after fun-fet,
will not be able to keep all thofe vapours diflblved,
but mufl: let fome part of them coalefce into very
fmall vifible particles, that form thofe fnijis^ which
appear to rife from marfliy grounds in a fummer’s
evening. The vapours near the ground, being more
denfe and copious, will be firfl; affected by the cold,

Y 2 and

[ i64 ]

and afterwards thofe that are thinner and higher up,
fo that the mill: will be low at firll, but will increale
in height afterwards 5 but belides, thefe grounds, and
the water they contain, will acquire fuch a heat from
the fun, that they may retain it for fome time, and
communicate it to the contiguous air, fo that the va-
pours may continue to rife for fome time after fun-
let, and will become vifible when they get up a little
way in the cooler air. Thofe cold thick morning
fogs, I mentioned juft now, are often attended with
a very light fmall rain; for we then fee the drops at
their firft formation, and they are fuch as are gene-
rally met with in palling over high mountains; fo that
it feems the drops of rain are very fmall when firft
formed in the clouds ; but being driven about by the
motion of the air, in their defcent, fome of them
will probably touch each other, and run into a drop
of a larger fize, and the farther they have to fall,
the more will their fize be increafed before they
come to the ground. And, for this realbn, the drops,
which fall from the higher clouds in fummer, arc
found to be generally larger than they are in winter,
when the clouds are low. It has been likewife ob-
fcrved, that the drops of rain are remarkably large
that fall in thunder Ihowers ; of which the realon
may be, that the lightning burfting from a cloud,
and expanding itfelf greatly, will fuddenly remove
the air from its place, which air, therefore, muft re-
turn to its place with great violence, and thereby the
watery particles in the clouds will be ftrongly agi-
tated and dallied againft each other, by which means
they will form themfelves into larger drops than at
Ollier times ; or, perhaps it may be faid, that when

a cloud

[ ]'

a cloud is filled with lightning, which is the fame as^
the eledric matter, the watery particles, like other
eledrified bodies, will repel each other, but being
fuddenly deprived of this repelling matter, will by
their mutual attradion come together again with
fome velocity, and, therefore, will run into drops
larger than ufual.

When the wind blows from the fouth, it isgene=
rally warm, and comes replete with aqueous va-
pours, which it has dilToived j but coming into a colder
climate, it cannot there keep the fame quantity of>
vapours diflblved that it did before, and confequently
niufi: part with fome of them, and let them preci-
pitate j and, therefore, loutherly winds generally
bring us rain. On the other hand, when the wind
blows from^ the north, or any point near it, as it is
very cold, it cannot have difiblved a great deal of
aqueous vapours where it came from 5 and, therefore,
coming into a warmer climate, it is ready to dilTolve
more j and, on this account, thefe winds, if they,
continue long, are founu to be very dry and parch-
ing, and are generally attended with fair weather.

Thefe feem to be the principal effeds of heat and
cold in caufing the air to dilTolve, aud take up, or
let go, and precipitate the aqueous vapours, and .
in conlequence of which we lometimes perceive
changes of the weather, even when there is no •
change in the height of the barometer.

But condenfation and rarefaction will alfo have the;,
like.efieds in promoting the folution of water in air,
or in caufing fome part of what has been diffolved.
to return again into water. and precipitate. It leems
reafonable to fuppofe, that .denfe air, , in which the

particles

[ ]

particles lie very near each other, will be better able to
dilTolve and keep fufpended a greater quantity of water,
than the fame air when diffufed thro’ a greater I'pace.
But that this is really fo we have an experimental
proof. For when a receiver is partly exhaufted, we
lee the rarefied air begin to let go the water it con-
tained, which gathering into fmall particles appears
like fteam or fmoak falling to the bottom. In order
to prove the fame thing by another experiment, I
.took from the air pump a large exhaufled receiver
twenty inches long, having at the bottom a brafs
plate, with a ftop-cock in the middle of it ; when
the flop-cock was opened, the external air, rulhing
in violently, and being much rarefied, let go the wa-
ter it contained, and threw it againfl the other end
of the receiver, where it ftuck on the glafs, and co-
vered it with a thin dew, which I found to increafe
.until the receiver was almoft full of air.

Thefe experiments prove that air, when rarefied,
cannot keep as much water diffolved as it does in a
more condenfed ftate. Hence we muft conclude,
that when the atmofphere is much faturated with
water, and changes from a denfer to a rarer date,
the higher and colder parts of it efpecially, will
begin to let go fome part of the water dilTolved ;
which will form new clouds, or add to the fize and
number of the particles before formed, and thereby
render them more apt to fall down in rain. On the
contrary, when the atmofphere changes from a rarer
to a denfer date, it will then be able to flop the pre-
cipitation of the water, and again diffolve in the
whole, or in part, fome of thofe clouds that were
formed before, and confequently will render their

particles

[ 1^7 ]

particles lefs apt to run into drops, and fall down
in rain. And thus we generally find, by expe-
rience, that the rarefied and condenfed ftates of the
atmofpherc are refpeaively attended with rain and
fair weather ; though this does not happen at all
times, for the air, though rarefied, may not then
abound rnuch with aqueous vapours, having already
parted with a good deal of them j fo likewife, when
the air is denfe and heavy, it. may then be much
loaded with vapours, which will increafe its weight ; .
and indeed it muft be fo after a long continuance of.
iair weather, fo that we may then . have rain even
before the atmofphere changes to a rarer date.

Upon this principle I think we may account for
the changes of the weather, which ufually attend,
the rifing and falling of the mercury in the baro-
meter, better than by faying, that when the air
grows rarer and lighter, it cannot by the laws of.
hydroftaticks fo well fupport the clouds and vapours,
and therefore muft permit them to fall down in
drops of rain ; for when the air grows rarer, although
the clouds will defcend into a lower and denfer part
of it, yet they will be there fupported^ and I do
not fee why their particles fhould be more apt to run.
into drops there, than when they were higher up, un-
•lefs^ they received fome addition from the water de-
polited among them, by the rarefied air, in the
rnanner I have juft now mentioned. For fince the
air is rarefied gradually, the clouds can defcend but
very flowly ; and, therefore,, their particles will not
be fo much prefted together by the refiftance they
meet with in their defcent, as they generally are .by
the winds which blow. upon them.

When

[ i68 ]

When the atmofphere is much fatu rated with wa-
ter, and grows colder or rarer than it was before, wc
fhall then perceive the lower air begin to part with
fome of the water it contains, which will fall infen-
iibly to the ground, or adhere to the walls of houfes,
or other bodies expofed to it, and make them be-
come damp and wet. And if the moifture fettles
on the fmooth furfaces of cold bodies, fuch as mar-
ble or other ftoncs, whofe pores cannot imbibe it, it
will cover them with a kind of dew, and then thofe
bodies are vulgarly faid to fweat.

At this time the hygrometer being affedled by the
moidiure will point to wet^ and, as we perceive from
thence, that the air is difpofed to part with the wa-
ter it contains, we may generally expedl rain. But
when the air again grows warm or denfe, it will be
able again to dilTolve, and take up the water it before
depofited, and the moifture on the bodies expofed
to it will difappear, the hygrometer will point lo dry,
and we may then promife ourfelves fair weather.

I obferved before, that, if a bottle be filled with a
very cold liquor, and expofed to the warm air, a
dew will foon be formed on its furface by the moi-
flure which the cold air depofites. Now if we fup-
pofe this body flill to retain the fame degree of cold,
whilfi: the air pafles over it, the dew on its furface
will continually increafe, and run down its fides in
fmall ftreams of water. This feems to be exadtly
the cafe of mountains, whofe tops reach into the colder
parts of the atmofphere ; and which, therefore, are
themfelves colder than the air is in general. For when
the wind blows the lower parts of the atmofphere
(which are the warmeft and mofl: replete with va-
pours)

[ 169 ]

pours) againft the fides of the mountains, being
there flopped in its courfe, it mufi; neceffarily afcend
and pafs over their tops. This air, therefore, will be
confiderably cooled in its progrefs up the Tides and
over the tops of the mountains, and confequently
mufl let go a great part of the watery vapours it
contains j which will be precipitated in dew and
nioifture upon the furface of the mountain, where
it will foak into the earthy parts, or infinuate itfelf
into the chinks and crevices of the rocks, where being
colledled, it will afterwards break out in fprings and
fountains, and become the fource of rivers, which
aie known always to take their rife in mountainous
countries j and, on this account, we might have
fmall fprings and rivers near mountains, although
there were neither clouds nor rain. But the moi-
flure, which the air ufually depofites on the moun-
tains, muft be confiderably increafed by the clouds,
which are driven againfl them-, and accumulated by
the winds, for their particles being then prelfed to-
gether will run into fmall drops of rain. Befides, it
is well known, that mountains do gather and retain
the clouds about them by their attradlive force, in
confequence of which we often fee fome clouds con-
tinue at reft on the mountains, whilft the others are
carried on gently by the wind ; hence it is, that
countries, in the neighbourhood of high mountains,
are the moft fubjedl to frequent rains.

Thus I have fhevv^n how the afcent of aqueous va-
pours, and their conftant cireuladon, by precipitating
again in moifture, or drops of rain, will arife from the
dilfolving power of theair, influenced by the viciflitude
of heat and cold, rarefaction and condenfation. For we

VoL. LV. 2 find,

[ 170 ]

find, by experience, that the heat and cold, which
we feel, does not either fo much rarefy, or lb much
condenfe the air, but that the former may fiiil in-
creafe, and the latter lefien the evaporation of fluids.
Nor, indeed, does the Ifate of the atmofphere in
general, as to rarity and denfity, depend upon the
heat or cold we experience here below. Thefe
caufes, therefore, according as they take place, in
different degrees, will occafion thofe various fiates
of the atmofphere, in refpedt to drynefs or moiflure,
which we experience in the feveral changes of the
weather. To which the winds contribute very much
by heating or cooling, condenfing or rarefying, the
different parts of the atmofphere ; and, by pro-
moting the folution of water in air, as they mix
thofe two fluids together, or when the air is already
faturated with aqueous vapours, by prefiing together
the particles in the clouds, and thereby caufing them
to run into drops. And thus, from the knownproper-
ties of folution, we may account in a fatisfad:ory
manner for the afcent and circulation of aqueous
vapours, and the feveral phasnomena of the atmo-
fphere arifing from thence, which is a great confir-
mation of the argument brought to prove that eva-
poration is only a particular fpecics of folution * j

■* Some time after this efTay had been read at a meeting of
the Royal Society, the author was informed that the Abbe
Nollet (to whofe works he was then an entire ftranger) had con-
fidered evaporation as a kind of folution; and, having lately look-
ed into his leftures, he finds the Abbe offers it as a conjecture,
that the air may perform the office of a folvent and a fpunge in
regard to the bodies it touches ; but this he does not prove,
nor does he afterwards apply this principle of folution, in ac-
counting for feveral phzenomena that depend on the nature of

4 and,

[ I?! ]

and, therefore, that they both proceed from the
fame caufe, to wit, the attradtion that obtains be-
tween the minute particles of different bodies, and
which is the means of carrying on fo many other
operations of nature. And, indeed, upon this prin-
ciple, air feems better fitted to be a general folvent
than any fluid we know of, becaufe its particles, not
attracting each other, are more at liberty to unite
themfelves to the minute particles of other bodies,
which they do attraCt, and accordingly we find the
atmofphere contains in it bodies of all kinds.

The particles of volatile fpirits, which are fj
eafily, and fo much rarefied by heat, feem to cohere
very llightly together, and, therefore, may be more
readily attracted by the air, and evaporate more
quickly than other fluids. The particles of odori-
ferous bodies feem to be ftrongly attracted by the
air, as they are fo readily difperfed through it, and
camphor i which is a light volatile body, may be in-
tirely diffolved in the air, without leaving any re-
mainder. The air abounds with vitriolic and other
acids, as is plain from the rufting of iron expofed
to it. It abounds alfo with fulphurous, nitrous, and
other inflammable particles, as appears by the frequent
meteors kindled in it. In fhort, the atmofphere, as

evaporation, but has recourfe to others of a different kind.
Now as the Abbe’s works have been fome years publifhed, it
might be fufpeCted that the author of this effay had borrowed a
hint from thence without acknowledging it, which would have
been difingenuous : he, therefore, thinks himfelf obliged to de-
clare, what is certainly true, that he has not here reprefented
any thing as new, which he was confcious had ever been pro-
pofed by any one before him, even as a conjecture.

Z 2 Dr.

[ 172 ]

Dr. Boerhaave obferves, may be confidered as a
chaos containing particles of all kinds of matter.
And, here it may be obferved, that the feveral fluids
that are diflblved in the air, will probably aflafl: in
diflblving and taking up the fubtile effluvia, which
are carried off from volatile bodies. The air, we find,
is neceflary for the prefervation of animal lifej but
when it has palled two or three times through the
lungs of an animal, it becomes unfit for refpiration,
and an animal inclofed in fuch air will foon expire ;
whether the air we breathe depofites in our lungs any
kind of matter neceffary to the fupport of life, I can-
not pretend to judge. But I think we may be fure
that one purpofe for which air was defigned, is the
carrying off that rnoifture, and other perfpirable
matter, which conftantly exhales from the lungs.
Now as air lofes nothing of its elafticity, by pafflng
through the lungs, it will flill continue fit for fuch
purpofes, in the animal oeconomy, as may be anfwer-
ed by the alternate expanfion and contraction of the
lungs in refpiration. And, therefore, I believe that
air is rendered unfit for refpiration, chiefly by being
faturated with that moiflure, and other perfpirable
matter, which it meets with in the lungs, and
thereby lofing its power of diflblving, and carrying
off any more of that kind of matter, which will then
continually increafe and clog the lungs, fo that an
animal inclofed in fuch air will die, perhaps fome-
what in the fame manner, though not fo quickly as
if it had been drowned.

Does it not feem probable that, in the conflant
and quick evaporation of moiflure from the lungs,
ioiue degree of cold may be produced, as it is in

other

[ 173 ]

Other evaporations, which, together with the frefli air
taken in, may ferve to cool the lungs, and the blood
palling through them ^ ?

* As air, even when incorporated with water, does not lofe
its elafticity, I took it for granted, that it would not become
lefs elaftic by paffing through the lungs of an animal. But being
told, that the contrary opinion was held by fome, who fuppofed
that air, having palled through the lungs of an animal, became
unfit for refpiration by lofmg its elafticity, I refoh'ed to try how
the fadl was, by the following experiment. In a receiver eight
inches diameter, and twelve inches high, having under it a foft
piece of oylcd leather, I included a pretty large chicken, and tied
the receiver clofe down to the table ; through a hole in the top
of the receiver went a glafs tube, open at both ends, cemented
round the hole with wax, the lower end was immerfed in water
(tinged blue) which flood in a glafs under the receiver. In
about an hour after the chicken was included, it grew very much
diftrefted, gaped wide, and breathed with great difficulty, and
in half an hour more it feemed almoft ready to expire ; the
infide of the receiver was then covered with moifture, which in
fome places ran down in drops. Now if the included air had
loft any of its elafticity by paffing through the lungs of this ani-
mal, it could not have prefl'ed fo ftrongly on the water in the
glafs as it did at firft, and then the external air would have
preft'ed through the tube, and appeared coming up through the
water in bubbles ; but no fuch thing happened, for as foon as
the receiver was tied down, the water in the tube rofe about one
fifth of an inch above the water in the glafs, and fo continued
during the whole time of the experiment, except that it rofe
and fell near one tenth of an inch every time the chicken breath-
ed ; and thefe vibrations of the water in the tube, I obferved
grew flower, and moved through a greater fpace towards the
latter end of the time ; which, fhewed that the chicken then
took in more air every time it breathed than it diJ at firft. After
things had flood thus above an hour and a half, and thofe who
faw the experiment were convinced that the included air had not
jofl any of its elafticity, though grown quite unfit for refpira-
tion, the animal being ready to expire in it, I thought it unne-
c'clfary to confine the chicken any longer, and it foon recovered.

Air

I

[ 174 ]

Air is not lefs neceflary for the fupport of fire
than of animal life, for fire will not long conti-
nue to burn without a circulation of frefh air, which
I fuppofe happens not from its adding any thing to
the pabulum of fire (for that feems unneceflary)
but rather on this account.- The air immediately
about a body on fire, is heated and made fpecifically
lighter than the air at fome diftance from it. This
hot air muff, therefore, afcend and carry with it all
thofe minute particles of different kinds, which are
thrown off from the burning body, and which other-
wife would reft upon its furface, and thereby clog
and flop the fubtile vibrations of the burning matter,
in which the nature of fire partly confifts. If,
therefore, fire be confined in a clofe place, where
there can be no circulation of frefli air, the air about
it being foon faturated, with the particles arifing from
the burning matter, will not be able to take up any
more of them, and, therefore, the fire muft go out
fmothered as it were in its own allies. And hence
it is, that fire burns fafter when air is ftrongly blown
upon it ; for this air carries off the aflies as faft as
they are formed on the furface of the burning bo-
dy, and thereby keeps thofe particles that have juft
taken fire quite free from any thing that can impede
or clog their vibratory motion. This air will alfo
fpread the fire quickly through the fuel, by blowing
the particles. that are already kindled amongft them
that are notj and, perhaps, the motion of the air
may promote thefe fubtile vibrations in the burning
matter, by which the fire is propagated through its
parts.

Though

[ 175 ]

Though the particles of fluids, in common evapo-
ration, are raifed into the atmofphere, by the at-
trading and diflblving power of the air, yet in fome
particular cafes vapours will rife into the air on an-
other account j for in fome places the earth often
fends forth hot elaftic vapours that rife into the air
by means of their elaftlcity, and carry with them
mineral particles of different kinds. Fermentation
generates elaflic vapours, which expand themfelves
into the air. And the particles of water, when
fufflciently heated, acquire a repelling force, which
feparates them from the furface of the water, and
" throws them upwards into the air. But all thefe
vapours foon lofe that elafticity by which they were
firlf raifed, and they are then retained, and kept
fufpended in the air, by the fame power that keep
fufpended all thefe vapours that rife without any
elaflicity in common evaporation. That the parti-
cles of fleam, which rifes from hot water, are en-
dued with a repelling force, appears plainly when
water is boiled in a clofe veffel j for then the fleam
becomes fo exceedingly elaflic, that, unlefs proper
caution be ufed, it will burff the ffrongefl veflel.
In this cafe the boiling water, being ftrongly prefled
by the force of the included fleam, conceives a much
greater heat, than it will do in an open veflfel ; for
even when water is boiled in the open air, it is fome-
M^hat hotter when the atmofphere is heavy, than
when it is light, which fhews that prefiure, upon
boiling water, increafes its heat j the reafon of which
we fliall fee prefently.

But the mofl: remarkable phasnomenon that at-
tends the boiling of water, is thofe large bubbles

which

[ 176 ]

which continue to rife from the bottom whilfl; even
the water boils, and long after all the air is driven
out of it. Dr. Boerhaave, in his Elements of Che-
miflry, part II. has proved, by feveral arguments,
that thefe bubbles do not arife from air ; and with
regard to their produdion, he feems to be of the
fame opinion with Stairs (to whofe work he refers)
that they arife from lome adive fires refiding in the
water. Mariotte, whom he alfo mentions on this
occafion, calls thefe bubbles fulminations, and fup-
pofes that they may arife from fome faline particles
contained in the water, which being heated ad in
the fame manner with the aurura fulminans. I find
it is a received opinion (but how generally I cannot
tell) that thefe bubbles are occafioned by fome fub-
tile elaflic fluid, tranfmitted from the fire through
the bottom of the vdlel. However, I conceive that
the fluid fo fubtile as to pals readily through the
bottom of the velTel, would pafs alfo through the
water fo ealily as not diflurb it ; and, therefore, I
liave for fome time fufpeded that thefe bubbles are
formed only by an dajiic Jleaniy in the manner I
lhall now deferibe. The particles on the furface of
the water long before it boils, will, by means of
the repelling force, which the heat introduces amongfl
them, rife in fteam, and will infinuate themfelves
into the air, which yields eafily to them ; but thofe
particles that are prelfed againft the bottom, by the
weight of the atmofphere, and of the incumbent
water, will require a great degree of heat to render
them fo elaftic, that they fliall be able to overcome
this refiftance, and expand themfelves into a greater
fpace. Now lince heat expands water, and makes

C 177 ]

Its particles repel each other according to its different
degrees, we may reafonablyfuppore that thefe particles,
from their being in contadl with the bottom of the
veffcl, may, at length, acquire fuch a degree of heat
as will give them a repelling force fufficient to over-
come the preffure they fuftain, and expand them
fuddenly into thofe large bubbles that afcend through
the water when it boils violently. I have lately
made fome obfervations and experiments, which
feem very much to favour this opinion. Thefe
bubbles, which afcend from the bottom, I obferved
always grow lefs before they reach the furface, and
thofe fmall bubbles, which adhere to the bottom,
for fome time before they afcend, often difappear
intirely before they reach the furface ; which fhews,
that when the matter they contain, or any part of
it, lofes the heat it had at firlf, it is turned into wa-
ter. When water, that has juft boiled, is poured into
a glafs, and fet under the receiver of an air pump, and
the air is almoft drawn out, the water appears to
boil more violently than it does on the tire; and
the bubbles do not all rife from the bottom, but
break out from other parts of the water, efpecially
towards the middle, where we may fuppofe it hotteft.
In this cafe no fubtile fluid can be fuppofed to rife
through the bottom of the veffel ; but the heat,
which the water retains, will give its particles an
elaftic force fufficient to overcome the preffure of
what little air remains in the receiver, and expand
them into bubbles; and that thefe bubbles are
corapofed of fteam appears plainly from this expe-
riment, for as foon as they begin to afcend, the re-
ceiver is filled with fteam, which being condenfed
V-OL. LV. A a by

1

[ 178 ]

by the cold, runs plentifully down its fides in water.^
After a veffel of water had boiled till all the air bub-
bles were driven out of it, I turned upon its mouth
a large glafs that lay in the water j the bubbles that
afcended under the glafs remained in the upper parr
of it, and forced out the water it before contained,
and then the elaftic matter in the glafs overturned
it, againft the fide of the veffel, and burfting out
afcended to the top in one large bubble, upon which
the fteam on the furface appeared to be much in-
creafed. Now this fliews that the matter contained
in thofe bubbles, which is quite tranfparent, being a
very rare and homogeneous fluid, appears afterwards
like fleam when it is mixed with the air. But I
thought I fhould make a more decifive experiment,
if I could obferve the effedls of very hot fleam con-
veyed under boiling water. Therefore when an
aeolipilc had boiled till the air was all driven out of
the water it contained, without taking it off the fire,
I immerfed its pipe into a veffel of water which had
juft been boiled, and immediately the fteam, which
iffued from the pipe, rofe up in very large bubbles
through the water, and made it feem to boil violently.
Then I held a large glafs of cold water, fo that the
pipe of the boiling ceolipile was immerfed into it. At
firft none of thele large bubbles appeared ; for the,
fteam being then condenfed by the cold water, was
mixed with it, making a very uncommon noife j
but as foon as the water in the glafs - grew very hot
this noife ceafed, and the fleam being no longer
condenfed rofe in large bubbles, and made the wa-
ter .appear to boil with great violence.

Thdc

[ 179 ]

Thefe obfervatlons and experiments feem to difco-
ver to us fully the nature of thofe bubbles that
afcend through boiling water. And from hence I
think we may learn the reafon why any fluid, in an
open veffel, will acquire only a certain degree of
heat when it boils, and will not grow hotter after-
wards?; and why different fluids will acquire different
degrees of heat in boiling ? The parts of the fluid
neareff the bottom grow hot at firff, and being then
expanded and made lighter, they afcend and change
place with the colder and heavier parts ( which
occajions that intejiine motion we perceive m liquors
while they are growing hot) ; and thus the heat
of the whole will increafe, until thofe particles,
that are in contact with the bottom of the veffel,
acquire fuch a degree of heat as will give them
a repelling force able to overcome the weight
of the atmofphere, the weight of the incumbent
fluid, and the tenacity of its particles; and then
they be fuddenly expanded into bubbles of

fteara, and afcend quickly to the top, without com-
municating this heat to the furrounding fluid: for
as thefe bubbles have a degree of heat but little fu-
perior to that of the fluid, and jufl fuffleient to keep
them expanded, if they were to lofe this heat, by
communicating it to the fluid in their afeent, they
would all difappear before they got to the furface ;
or if the whole fluid was to grow as hot as the bub-
bles, it would, like them, be all turned into elaflic
fleam ; and, therefore, the fluid itfelf cannot grow
hotter than when thefe bubbles began to afcend.

That thefe bubbles are really hotter than the other
parts of the fluid I found by the following experi-

A a 2 ment.

C ]

merit. A tin veffel, about nine inches in diameter,

' was fet on the fire, fo that the water on one fide only
boiled violently, but the motion arifing from thence
made all the water circulate through the vefiTel ; and,
therefore, all the water (after the vefiel had boiled
for fome time) mu ft have acquired the fame degree
of heat. I then held a mercurial thermometer, with
Fahrenheit’s fcale, under the water ; where it was
juft out of the reach of the bubbles, it rofe there
no higher than to 2 1 1 ; but when it was held among
the bubbles, where they afcended thickeft, it rofe
to 212, which is ufually reckoned the mean heat of
boiling water, though it feems rather to be the heat'
of the (team contained in the bubbles ; and, there-
fore it is fomewhat greater than the heat which wa-
ter will bear without being turned into fleam. Thc'
heat of the water was not then fo great as it fome
times is, for the atmofphere was then very light, the-
barometer flanding at 29.

From what has been faid, it follows, that the de-
grees of heat neceflary to raifc thefe bubbles in any
fluid, and make it boil, will be greater as the fluid
is more flrongly prefiedi and as its particles are more
tenacious or vifcid. And this we find is exadtly
agreeable to experience. For fpirit of wine, which'
is a fluid very light, eafily rarefied, and in no degree
vilbid, will boil with a lefs heat than water does.
But mercury, whofc particles are heavier, and oil op
pitch, whofe particles are more vifcid, than thofe of
water, will require a much greater degree of heat to
make it boil than water does. And it is knowiv
that water boiled in a clofe veffel, where it is firong-
ly prefled by the confined elaflic fleam, will become

much

[ ]

much hotter than when boiled in the open air 5 fo
that if the clofe veffel fhould burd, or be opened
fuddenly, I doubt not but the whole body of the
water would immediately expand itfelf into deam,
and fly out of the veflel with great violence. .

I know not whether thefe experiments, and the
obfervations founded upon them, will appear new
to you as they did to me j fuch as they are, I fub-
mit them to your confideration j and.am,

S I R,

With great refpedt,' .

Your mod obedient*

Humble fervant, ,

Trinity College, Dublin,
March 5, 1765.

Hugh Hamilton.:

xxiv:

1

[ ]

XXIV. Phyjical and Meteorological Oh/ef^a-
tio?ts^ ConjeBures^ and Suppofetions^ by Ben-
jamin Franklin, L,L, D, and F. R, S, *

Read June 3,
1756.

TH E particles of air are kept at a
diftance from each other by their

mutual repullion.

Every three particles mutually and equally re-
pelling each other, mufl form an equilateral tri-
angle.

All the particles of air gravitate towards the earth,
which gravitation comprelles them, and fliortens the
fides of the triangles, otherwife their mutual re-
pellency would force them to greater diftances from
each other.

Whatever particles of other matter (not endued
with that repellency) are fupported in air, muft ad-
here to the particles of air, and be fupported by
them ; for in the vacancies there is nothing they can
reft on.

Air and water mutually attradl each other. Hence
water will diflblve in air, as fait in water.

The fpecific gravity of matter is not altered by di-
viding the matter, though the fuperficies be increafed.
Sixteen leaden bullets, of an ounce each, weigh as
much in water, as one of a pound, whofe fuper-
ficies is lefs.

On reading the preceding paper in the Society, it was rc-
colle£led that this paper, fimilar in fomc particulars, had been
communicated to the Society about nine years before, though
not till now printed.

Therefore

[ i83 ]

Therefore the fupporting of fait in water is not
owing to its fuperficies being encreafed.

A lump of fait, though laid at reft at the bottom
of a veffel of water, will diflblve therein, and its
parts move every way till equally diffufed in the waterj
therefore there is a mutual attradtion between water
and fait. Every particle of water affumes as many
of fait as can adhere to it j when more is added, it
precipitates, and will not remain fufpended.

Water, in the fame manner, will dilTolve in air,,
every particle of air affuming one or more particles

of water j when too much is added, it precipitates
in rain.

But there not being the fame contiguity between .
the particles of air as of water, the folution of wa-
ter in air is not carried on without a motion of the '
air, fo as to caufe a frefh acceffion of dry particles.

Part of a fluid, having more of what it diflblves, .
will communicate to other parts that have lefs.
Thus very fait water coming in contadt with frefh,
communicates its faltnefs till all is equal, and the,
fooner if there is a little motion of the water.

Even earth will diflblve, or mix with air. A ,
flroke of a horfe’s hoof on the ground in a hot
dufty road, will raife a cloud of duft, that lhall, if
there be a light breeze, expand every way till perhaps
near as big as a cemmon houfe. Tis not bv me-
chanical motion communicated to the particles of dull
by the hoof, that they fly fo far, nor by the wind
that they fpread fo wide. But the air near the ground,
more heated by the hot duff Ifruck into it, is rariiied
and rifes,^ and in riling mixes with the cooler air, and
communicates of its duff to it, and it is at length fo

diffufed i

[184]

' xliffufed as to become invifible. Quantities of dull
are thus carried up in dry feafons. Showers wafh it
from the air and bring it down again. For water
attradling it dronger, it quits the air and adheres to
the water.

Air fuffering continual changes in the degrees of
its heat, from various caufes and circumftances, and
oonfequently changes in its fpecific gravity, muft
therefore be in continual motion.

-A fmall quantity of fire mixed with water (or de-
gree of heat therein) fo weakens the cohefion of its
particles, that thofe on the fiirface eafily quit it, and
adhere to the particles of air.

, A greater degree of heat is required to break the
cohefion between water and air.

Air moderately heated will fupport a greater quan-
tity of water invifibly than cold air j for its particles
being by heat repelled to a greater difiance from
each other, thereby more eafily keep the particles of
water, that are annexed to them, from running into
cohefions that would obfirudt, refradt, or refledt the
light.

Hence, when we breathe in warm air, though the
fiime quantity of moifiure may be taken up from
the lungs as when we breathe in cold air, yet that
moifiure is not fo vifible.

Water being extremely heated, /. e. to the degree
of boiling, its particles, in quitting it, fo repel each
other, as to take up vafily more fpace than before,
and by that repellency fupport themfelves, expelling
the air from the fpace they occupy. That degree of
heat being lefiTened, they again mutually attradf, and
having no air-particles mixed, to adhere to, by
2 which

[185]

which they might be fupported and kept at a di-
flance, they inftantly fall, coalefce, and become wa-

ter again.

The water commonly diffufed in our atmofpherc
never receives fuch a degree of heat from the fun,
or other caufe, as water has when boiling j it is not,
therefore, fupported by fuch heat, but by adhering
to air.

Water being diflblved in, and adhering to air,
that air will not readily take up oil, becaule of the
natural repellency between water and oil.

Hence cold oils evaporate but flowly, the air
having generally a quantity .of diifolved water.

Oil being heated extreamly, the air that approaches
its furface will be alfo heated extremely ; the water
then quitting it, it will attradl and carry off oil,
which can now adhere to it. Hence the quick eva-
poration of oil heated to a great degree.

Oil being diffolved in air, the particles to which
it adheres will not take up water.

Hence the fuifbcating nature of air impregnated
with burnt greafe, as from fnuffs of candles, and the
like. A certain quantity of moiffure fhould be every
moment difeharged and taken away from the lungs.
Air that has been frequently breathed is already
overloaded, and for that reafon can take no more,
fo will not anfwer the end. Greafy air refufes to
touch it. In both cafes fuffocation for want of the
difeharge.

Air will attrad and fupport many other fub-
dances.

A particle of air loaded with adhering water, or
any other matter, is heavier than before, and would
defeend.

VoL. LV. B b

The

C ]

The atmofphere fuppofed at reft, a loaded de-
Icending particle muft adl with a force on the par-
ticles it paftes between, or meets with, fufticient to
overcome in fome degree their mutual repellency,
and pufli them nearer to each other.

A Thus, fuppofing the particles

o o o A B C D, and the others near
FO BO CO GO them, to be at the diftance
o DO o caufed by their mutual repel-
o o o o Icncy (confined by their com-
E mon gravity) if A would de-

fcend to E, it muft pafs between B and C. When it
comes between B and C^it will be nearer to them than
before, and muft either have puftied them nearer to
F and G, contrary to their mutual repellency, or
pafs through by a force exceeding its repellency with
them. It then approaches D, and, to move it out of
the way, muft ad on it with a force fufticient to
overcome its repellency with the two next lower par-
ticles, by which it is kept in its prefent fituation.

Every particle of air, therefore, will bear any
load inferior to the force of thefe repulfions.

Hence the fupport of fogs, mifts, clouds.

Very warm air, clear, though fupporting a very
great quantity of moifture, will grow tuibid and
cloudy on the mixture of a colder air : as foggy tur-
bid air will grow clear by warming.

Thus the fun ftiining on a morning fog, difftpates
it. Clouds are feen to wafte in a funftiiny day.

But cold condenfes and renders viftble the vapour.
A tankard, or decanter, filled with cold water, will
condenfe the moifture of warm clear air, on its
outfide, where it becomes viftble as dew, coalefccs
into drops, defcends in little ftreams.

4

The

[ ^^7 J

T atmofphere moft near

the furface of the earth ^ for there, befides the dired

tnany refledions. Moreover, the earth
itlelf being heated, communicates of its heat to the
neighbouring air.

The higher regions having only the dired rays of
the lun palling through them, are comparatively very
• Hence the cold air on the tops of mountains
and fnow on fome of them all the year, even in the
torrid zone. Hence hail in fummer.

If the atmofphere were, all of it (both above and
helow) always of the fame temper as to cold or heat,
then the upper air would always be rarer than the
o\\er, becaulc the prelTure on it is lefs ^ confequently
iightei, and therefore would keep its place.

But the upper air may be more condenfed by cold,
than the lower air by prellure. The lower more
expanded by heat, than the upper for want of pref-
nire.^ In fuch cafe, the upper air will become the
heavier, the lower the lighter.

The lower region of air being heated and expand -
ed, heaves up and lupports, for fome time, the
colder heavier air above, and will continue to fupport
it while the equilibrium is kept. Thus water is fup-
ported in an^ inverted open glafs, while the equili-
brium is maintained by the equal prefiure upwards
of the air below ; but the equilibrium by any means
breaking, the water defcends on the heavier fide, and
the air rifes into its place.

The lifted cold heavy air over a heated country,
becoming by any means unequally fupported, or un-
equal in its weights, the heaviefi; part defcends fird,
and the reft follows impetnoufly. Hence gufts after
heats, and hurricanes in hot climates. Hence the

H h 2 air

[ i88 ]

air of gufts, and hurricanes cold, tliough in hot
climes and feafons ; it coming from above.

The cold air defcending from above, as it pene-
trates our warm region full of watry particles, con-
.denfes them, renders them vifible, forms a cloud
thick and dark, overcafling fometimes at once, large
and extenlive j Ibmetimes, when leen at a diftance,
fmall at fiift, gradually increafingi the cold edge,
or furface, of the cloud, condenfing the vapours next
it, which form fmaller clouds, that join if, encreafe
its bulk, it defcends with the wind and its acquired
weight, draws nearer the earth, grows denier with
continual additions of water, and difcharges heavy
fhowers.

Small black clouds thus appearing in a clear fky,
in hot climates, portend florms, and warn feamen to
hand their fails.

The earth turning on its axis in about 24 hours,
the equatorial parts mufl move about 15 miles in
each minute. In northern and fouthern latitudes this
motion is gradually lets to the poles, and there no-
thing.

If there was a general calm over the face of the
globe, it muff be by the air’s moving in every part,
as faff as the earth, or fea, it covers.

He that fails, or rides, has infenfiblv the fame
degree of motion, as the (hip, or coach, with which
he is conneded. If the fhip flrikes the diore, or the
coach ffops fuddenly, the motion continuing in the
man, he is thrown forward. If a man were to
jump from the land into a fwift failing fliip, he
would be thrown backward (or towards the Hern)
not having at firft the motion of the fliip.

He

[ 189 ]

He that travels, by fea or land, towards the equl-
noiflial, gradually acquires motion ; from it, lofes.

But if a man were taken up from latitude 40
(where fuppofe the earth’s furface to move 12 miles
per minute) and immediately fet down at the equi-
nodial, without changing the motion he had, his
heels would be ftruck up, he would fall weftward.
If taken up from the equi nodial, and fee down in
latitude 40, he would fall eaftward.

The air under the equator, and between the tro-
pics, being conftantly heated and rarihed by the fun,
rifes. Its place is fupplied by air from northern and
fouthern latitudes, which coming from parts where
the earth and air had lefs motion, and not fud-
denly acquiring the quicker motion of the equatorial
earth, appears an eaft wind blowing weflward, the
earth moving from wed to eaft, and Hipping under
the air.

Thus, when we ride in a calm, it feems a wind
againft us. If we ride with the wind, ahd fader,
even that will feem a fmall wind againd us.

The air rariiied between the tropics, and fifing,
mud flow in the higher region north and fouth. Be-
fore it rofe, it had acquired the greated motion the
earth’s rotation could give it. It retains fome de-
gree of this motion, and defeending in higher lati-
tudes, where the earth’s motion is lefs, will appear a
wederly wind, yet tending towards the equatorial
parts, to fupply the vacancy occafioned by the air of
the lower regions flowing thitherwards.

Hence our general cold winds are about northwed,
our fummer cold gufts the fame.

The

[ igo']

The air in fultry weather, though riot cloudy, has
a kind of hazinefs in it, which makes objeds at a
dihance appear dull and indiftind. This hazinefs is
occafioned by the great quantity of moifture equally
diffufed in that air. When, by the cold wind blow-
ing down among it, it is condenfed into clouds, and
fills in rain, the 'air becomes purer and clearer.
Hence, after gufts, diftant objeds appear diftind,
their figures fliarply terminated.

Extreme cold winds congeal the furface of the
earth, by carrying off its fire. Warm winds after-
wards blowing over that frozen furface will be chilled
by it. Could that frozen furface be turned* under,
and a warmer turned up from beneath it, thofe warm
winds would not be chilled fo much.

The furface of the earth is alfo fometimes much
heated by the funj and fuch heated furface not being
changed, heats the air that moves over it.

Seas, lakes, and great bodies of water, agitated
by the winds, continually change fur faces ; the cold-
furface in winter is turned under, by the rolling of
the waves, and a warmer turned up ; in. fummer,
the warm is turned under, and colder turned up.
Hence the more equal temper of fea-water, and the
air over it. Hence in winter, winds from the fea
feem warm, winds from the land cold. In fum-
mer the contrary.

Therefore the -lakes north-wefi: of us*, as they
are not fo much frozen, nor fo apt to freeze as the
earth, rather moderate than increafe the coldnefs of
our winter winds.

The air over the fea being warmer, and therefore
lighter in winter than the air over the frozen land,

^ In Penfilvania.

may

[ I9I ]

-may be another caufe of our general north- weft
winds, which blow off to fea at right angles from
our North American coaft ; the warm light fea
air rifing, the heavy cold land air preffing into its
place.

Heavy fluids defcending frequently form eddies,
or whirlpools, as is feen in a funnel, where the water
acquires a circular motion receding ev'ery way from
a centre, and leaving a vacancy in the middle, greateft
above, and leflening downwards, like a fpeaking
trumpet, its big end upwards.

^ i\.ir defceriding, or afcending, may form the fame
kind of eddies, or whirlings, the parts of air ac-
quiring a circular motion, and receding from the
fiddle of the circle by a centrifugal force, and leav-
ing theie a vacancy, if defcending, greateft above,
and leflening downwards; if afcending, greateft be-
low, and leflening upwards, like a fpeaking trumpet,
ftanding its big end on the ground.

When the air defcends with violence in fome
places, it may rife with equal violence in others,
and form both kinds of whirlwinds.

The air in its whirling motion receding every way
from the centre, or axis, of the trumpet, leaves there
a vacuum, which cannot be filled through the fides,
the whirling air as an arch preventing ; it muft then
prefs in at the open ends.

The greateft preffure inwards muft be at the lower
end, the greateft weight of the furrounding atmo-
fphere being there. The air entering rifes within,
and carries up duft, leaves, and even heavier bodies
that happen in its way, as the eddy or whirlpool
paffes over land.

If

[ 192 ]

If it pafies over water, the weight of the furround-
ing atmofphere forces up the water into the vacuity,
part of which, by degrees joins with the whirling
air, and adding weight, and receiving accelerated
motion, recedes ftill farther from the centre, or axis,
of the trump, as the prelTure leffcns, and at laft, as
the trump widens, is broken into fmall particles, and
fo united with air, as to be fupported by it, and be-
come black clouds at the top of the trump.

Thus thefe eddies may be whirlwinds at land,
waterfpouts at fea, A body of water fo raifed may
be fuddenly let fall, when the motion, &c. has not
ftrength to fupport it, or the whirling arch is broken ^
fo as to let in the air ; falling in the fea, it is harmlefs,
unlefs (hips happen under it. But if in the pro-
grefljive motion of the whirl it has moved from the
fea over the land, and there breaks, fudden, violent,
and mifehievous torrents are the confequence.

XXV. An

[ '93 ]

XXIV. Hijlorical Me??ioirs^ relating to the
PraSiice of Inoculation for the Small PoXy
in the Britifli American ProvinceSy parti-
cularly in New England : AddreJJed to
John Huxham, M, D. F, R, S, By
Benjamin Gale, A, M,

Read May 23, H E fmall pox, by the vigilant
X execution of the laws fubfifting, in
the feveral New England colonies, hath never ge-
nerally prevailed among the inhabitants, excepting in
Bodon, the capital town, in the province of the
MafTachufett’s Bay, where it has been epidemical,
A. D. 1649, 1666, 1678, 1689, 1702, 1721,
1730, 1752, and at this prefent time, 1764, and
where the fuccefs attending inoculation, after
much oppofition, and endeavours ufed to bring the
fame into difrepute, became inconteftably evident.

In the provinces of New York, New Jerfey, and
Penfylvania, the like precautions have not been taken,
and the fmall pox has prevailed in thofe provinces,
but more efpecially in the capital towns, and places
adjacent, once in about fix or feven years, where
inoculation hath been pradlifed with furprifing fuc-
cefs, to the prefervation of the lives of many.

A. D. 1702, the inhabitants of the town of
Bofton were 6750 fouls, at this time there died
of the whites 300. A. D. 1721, the number of
the inhabitants were 10,567, befides thofe moved out
to avoid the difeafe j the difcumbents were 5,989,
VoL. LV. C c whereof

[ 194 ]

whereof 844 died, t. e. near one in feven. At this
time, in and about Bofl.011, 286 were inoculated,
whereof 6 died, /. e. about i iii 48. This was
the beginning of inoculation in New England, Toon
after it was hrfl: pradliied in London A. D. 1730,
the difcumbents were eflimated at 4000, whereof
al^out 500 died j of not 400 inoculated, 12 died, /. e,
1 of 33.

A. D. 1752, there was an exad account taken, by
order of the magiftrates of the town of Bofton, and
rendered upon oath (in order to remove the prejudices
and objections made again ft inoculation) of all who
had the fmall pox, either in the natural way or by
inoculation, and of the precife number of thofe who
died of the fmall pox in either way j by^hich account
it appears that the number of thofe who had the di-
ftemper in the natural way, including blacks, amount-
ed to 5,544, of which number died, including
blacks, 514 j the whole number inoculated, including
blacks, was 2,113, of which died, including
blacks, 30. At this time, all prefent had the fmall
pox, except about I74i the total of refidenters (in-
cluding 1 544 negroes) being 15,734; thofe who
fled from the fmall pox eftimated at 1,800. Hi-
therto mercury had not been made ufe of in inocu-
lation in Bofton.

A. D. 1764, at this prefent writing, the fmall pox
is prevalent in the town of Bofton ; by the laft ac-
counts, 3000 had recoved from inoculation, in the
new method, by the ufe of mercury, and 5 only
had died, viz. children under 5 years; fo that it ap-
pears, that death without inoculation is i in 7 or 8 ;

* Dr. Douglas’s Summary Hift. Vol. II. p. 395.

by

. t ^95 ]

by inoculation without mercury, i in 8o or loO}
by inoculation with mercury, i in 800 or 1000.

The ufe of mercury, in the fmal! pox, wis
firil hinted by the learned Boerhaave, wlio died in
17385 this intimation was improved, and mercury
introduced into pra<ftice, by phylicians, in the Englifli
American colonies, about 1745.

Several American phylicians claim the fecond
glory to Boerhaave. Dr. Thomas of Virginia, and
Dr. Murifon of Long Ifland, in the province of
New York, may jufUy have merited that honour,
who have fuccefsfully pradifed by the ufe of mer-
cury, perhaps before any other, either in Europe or
America.

During the late war, the fmall pox was brought
into divers towns, in this and the other colonies, by
the return of our foldiers (employed in his ma-
jefty’s fervice, in the pay of the New England co-
lonies) for winter quarters, and by feamen employed
in our navigation to the Britifh iflands in the Weft
Indies, where the fmall pox was univerlally preva-
lent, which produced an univerfal concern among
the inhabitants, led the fame fhould become ge-
neral, and fpread through this and the other colonies
in New England. Whereupon application was made
to the legiflature of this colony, for liberty to inocu-
late for the fmall-pox, by the officers of our pro-
vincial troops and others, which was accordingly
granted ; as likewife that hofpitals for that purpofe might
be eredled, in fuch towns of the colony as fhould fee
caufe to permit the fame. However, indead of re-
gulating fuch hofpitals as fhould be eredted for that
purpofe, by well- adapted laws, to prevent any com-

C c 2 munication

[ 196 ]

munication with thefe hofpitals from abroad, or the
fubjedts of inoculation leaving the fame, without
licence from the attending phyfician, unhappily that
matters was left, to be regulated at the difcretion of the
overfeers of the feveral towns where inoculation
fliould be pradtifed, which required the ftridteft laws,
enforced by fevere penalties, without which it would
be impoffible for the attending phyfician to reftrain
his patients, when grown impatient with confine-
ment and a reclufe life.

From this defedl, fome perfons left the hofpitals,
not being duly cleanfed, and unhappily communi-
cated the fmall-pox to divers perfons, of which
fome died; whereupon the law permitting inocu-
lation was repealed, notwithftanding three hofpi-
tals had been eredled in this colony, at no inconfider-
able expence, and no further attempts were made, to
regulate the pradtice of inoculation, by meafures well
adapted for that purpofe.

Whereupon perfons engaged in trade, feamen,
and youth, living in fea-port towns, and places more
expofed to frequent invafions of the fmall-pox, re-
forted in great numbers to New York, in order to
obtain inoculation. On this emigration of the inhabi-
tants, and partly to prevent, but principally to fecure
againfi, the fpreading of the contagion in the colony,
the afiembly prohibited inoculation within the limits
of this colony, on very fevere penalties ; and in cafe
people went into any other government to obtain
it, ordered them not to return again to the co-
lony, without firfi: having remained out at leaf!
twenty days after leaving the hofpital, or place of
infedtion, upon the penalty of twenty pounds; and

[ 197 ]

if after remaining out of the colony twenty days,
they ihould unfortunately happen, either by their
cloaths or otherways, to communicate the infedion,
they were made liable to pay, to the party injured,
treble damages, and cofts of fuit. Thus the
pradfice of inoculation for the fmall-pox flands
wholly interdidted within the colony, and laid under
fuch difadvantages and difcouragements, when per-
fons go abroad to procure it, that we are in a great
meafure deprived of the only method, ever difcovered
to the world, to efcape the hazards attending that
difeafe, which has made fuch havock of the human
fpecies.

Was inoculation, upon fome of our fmall iflands
on the fea coaft, or on fome point of land, at a
proper diftance from inhabitants, impradicable, with
fafety to the inhabitants of this colony, I fhould
not think it unreafonable wholly to fupprefs it j but
without all doubt it may be fo regulated, as to be
wholly fafe, and without danger of communication ;
and therefore, I think, 1 may juftly fay, to deny
liberty of inoculation to perfons in trade, feamen, and
fuch as are more immediately expofed to the difeafe,
or to lay thofe who would go out of the colony to
obtain it under fo great difadvantages, is an inva-
fion of the natural rights of mankind, and an ol>
ftrudion to their purfuing the firft law of human
nature.

The well-peopling the colonies, and fecuring our
new acquiliiions, are matters of great importance to
our mother country, as well as to ourfelves ; and the
more it is effeded from the colonies themfelves,
without tranfporting- fettlers from the kingdoms of

Great-

[ igS ]

Great-Britain and Ireland, the greater advantages muft
accrue to the manufad;urers of the mother country
as colonizing from the plantations will keep the
price of labour at fo high a rate, as will cffediually
prevent our engaging in manufa^5tul•es, and greatly
encreafe the fale of Britilh manufadures in Ame-
rica.

The number of the inhabitants in our old American
fctllements double once in twenty or twenty- five
years, and in our-new made fettlernents, once in
fifteen or twenty years.

The New England colonies are better peopled than
the other provinces and colonies in America, which
I principally attribute to the tenure of our lands,
wich are held in fee-fimple, according to the tenure
of the Manor of Eafi Greenwich in Kent ; and I
humbly conceive nothing would fo much facilitate
the fettlement of crown lands, obtained by our new
acquifitions in America, as their being granted in
like manner: paying quit-rents to monopolizers of
large trads of land, is not well relilhed by Ameri-
cans, and has in itfelf a natural tendency to render
the defence of the country againfi: foreign invaders,
and our favage enemies, defpicably infamous. A
fignal inftance of this happened during the French
war, A. D. 1745. The colony of Connecticut having
juft before finiftied the fettlement of their new lands,
adjoining to the Manor of Livingfton, in the province
of New York, being on the north- weft frontiers of
this colony, fome fculking parties of Indians being
feen in the manor aforefaid, the tenants left their
fettlernents, which had been made almoft a century
before, and fled over into this country to our new-made

fettlernents,

[ 199 ]

fettlements, which then had not been made more
than feven years where they looked upon them-
lelves as fafe and fecure ; a convincing proof that no
men will face an enemy, like thofe who fight pro
^11 et focis. Our fouthern colonies, in particular,
have been drove before a defpicable enemy, like

infant

Itate of thefe colonies.

The cenfus of the inhabitants of this colony,
tranfruitted by Governor Fitch, A. D. 1756, by order
of the Lords of Trade, was 128,218 fouls whites,

1 7 blacks; that of the year 1762, 141,000

ous whi^s, 4590 blacks, of which 900 were
Indians. The levies of our fencible men diminilhed
e increafe, fo that the left feven years the colony
only lucreafed 13,000. On the peace, doubtlefs, the
apidity of population will recover; and in how
Ihort afpaceof time, the well fettling our new ac-
quifitions may be effected, from all the American
colonies colledively, I leave every one to determine;
and I cannot but think, that, whenever the date of
public affairs will permit the parliament of Great
Lntain to advert to the peopling and fecuring the

America, they will judge it
Deft effected, as much as may be, from her colonies
in America; and that the law prohibiting inocula-
tion in America will be accordingly annulled, by
their fuperintending authority, as prejudical to the
population of the colonies.

It appears from Dr. Douglafs's account of the
fmall-pox in ^ the town of Bofton, where he lived,
and made critical obfervations, the three lafl times
that It was epidemical there, viz. A. D. 1721, 1730,

and

[ 200 ]

and 1752, that the number of perfons vlfited with the
Imalhpox, in the natural way, was 16047, which
1858 died j and that in 1752, the number of thofe
who received the infedion by inoculation, before mer-
cury was made ufe of in Bofton in inoculation, amount-
ed to 2113 perfons, of which 30 died (blacks in both
being included) j granting that thofe who had the
difeafe in the natural way flood an equal chance for
life with thofe who were inoculated, it appears that,
in thofe three years, there died 1831, in the town of
Bofton only, for want of inoculation j by which
deaths, according to the longed; term of doubling
the number of inhabitants in America, in one cen-
tury from thofe periods, the number will be dimi-
niflied by 29,296, which is (from the beft calculation
I am able to make) a number far fuperior to thofe
who came from Europe, into the New England co-
lonies, from their fiifl fettlement, to this prefent
day.

Various fea-port towns, as well as fome inland
places, have been vifited with the fmall-pox, fince
the firfl fettlement of the New England colonies, by
which many have died ; perhaps, taken colledively,
not more than one in four have recovered, partly
owing to removing the fick, in order to prevent com-
municating the infedion ; and partly to the want of
fkilful phyficians, and faithful experienced nurfes to
attend the fick, which often obliged to make ufe of
fome of the mod abandoned wretches, for want of
fuitable perfons who had had the fmall-pox, to per-
form that fervice.

It is much regretted by many, that the pradice of
inoculation may not- be tolerated, in the New
England colonies, and regulated by laws, well adapted
4 to

[ 201 ] *

to prevent the fpreading the contagion, amongft fuch
as do not chufe, and thofe vvhofc circumflances will
not permit them, to comply with the expence at-
tending it.

The increafe of mankind has been more impeded
by the fmall-pox, than is ufaally imagined j it is not
the lols of^ne in fix or eight, who die with the
difeafe, that is chiefly to be attended to, but the ac-
cumulated lofs of all the poftericy, which might have
defcended from them, multiplied through allfucceed-
ing generations. Wherefore, perhaps, it might be
thought wifdom to addrefs the Throne for liberty to
eredt one hofpital in each of the New England colo-
nies for that purpofe ; that thofe, at leaft, who are en-
gaged in trade and navigation, might have the benefit
of inoculation, and be exempt from the hazard of the
difeafe, while neceffarily engaged in bufinefs abroad,
andymt endanger their friends on their return home.

I. Bleeding, at the firfl; invafion of the eruptive fe-
ver, mull be advantageous, when the blood is
rich and denfe, the cohefion of the compo-
nent parts llrong, the patient plethoric, and
the fever inflammatory..

n. Bleeding mull be prejudicial, if the quantity of
blood is below the flandard of health, and
fcrous, the coheflon of the conflituent compo-
nent parts weak, and the fever low and
deprelTed.

III. Bleeding will not alter the date of the blood,
and reflore the cohefion of its conflituent
component parts, when broken and diflblved ;
conlequently it will be of no fervice when at-
Vol.lv. D d tended

- [ 202 ]

tended with hemcrrhages, unlefs the patient
be plethoric, and the hemorrhages produced
by an injudicious intempefHve ufe of hot
alexipharmic medicines *.

IV. Bleeding in the fmall-pox will not be attended

with fuccefs, when it would not be of ad-
vantage in the fame fpecies of fever in any
other difeafe.

V. Mercurials alone are not to be relied on, in

order to leiTen the number of pudules, but
mud be prejudicial, when the blood is ferous,
its texture weak, or the diffolution of its
condituent component parts compleat.

A Summary of the feveral Methods ufed by the mod
reputable Inoculators in America.

1 Method. The fubjeds for inoculation are di-
rected to a light fmooth diet for 14 days preceding
the operation. All flilt food, fpirituous liquors,
butter, oil, &c. are interdiCled.

Calomel, ppt. 2 parts, fulph. aurat. antimon. i
part, and with a drong folution of g. arab.
f. pil.

Stib. nitrat. cremor. tart. fal. polychred. do. fulph.
p. a. m. f. pulv. refi igerans 3 30 or 40 grains to
adults.

* More have died in America, in the mcafles and fman-pex,
by fnake-root and liiffron, by the prd'eription of old women,
both male and female, than by both thde difeafes, where nature
has been left to hcrfclf.

P2 pulv.

[ 203 ]

pulv. jallap. fcammon. ftib. nitrat. cretnor. tartar,
p. a. m. f. pulv. cathart.

The day before inoculation, to adults, give 9 ij of
the purging powder, with 5 gr. of calomel. The
night following inoculation, give 10 or 12 gr. of the
antimonial pill, repeating ii: three nights fucceffively.
The morning after the third pill, give the cathartic
powder, then repeat the antimonial pill and purge as
before. The antimonial pill frequently purges and
vomits the fiift time of taking it. Every morning,
including the day of inoculation, a portion of the
refrigerant powder is given, except when the ca-
thartics are prefcribed, and continued until the
eruption. Phlebotomy is diredted, pro re nata,

2 Method. 5^ Pulv. antimon, crud. §vij. P. fal.
nitr. ^ iv. mif. f. pul. Deflagrate in an iron
ladle, fcrape off the fc.orias, and reduce it to
a fine powder.

5c Hujus pul. antim. gr. vj. calomel, ppt. gr. j. m. f.
pul. To an adult give it every night at bed-
time, eight nights fucceffively (regulating
the diet as mentioned above) ; then inoculate,
and repeat the powders, till the eruptive fever
comes on, unlefs the falival glands are afFedted,
in which cafe they are to be difcontinued ; and
upon the invafion of the eruptive fever, the
general antiphlogiftic method is purfued.

The third and lafl; method I fliall mention, is
taken from a very famous (although I dare not fay
the rnofl: judicious) inoculator, and is commonly

D d 2 entered

[ 204 ]

entered upon, and the operation performed, without
any regimen being previoufly enjoined, and often
after free indulgence. This ra(h inoculator prefcribes
to adults, from lo to 20 grains of calomel in an
anodyne bolus over night ; the next morning he exhi-
bits from 30 to 40 grains of pulv. cornachin. and the
day following he inoculates in the ufual form. The
calomel bolus i« prefcribed every other night, and the
next morning the pulv. cornachin. until four doles of
each are adminiftered. Every other night, crem,
tart, is boiled in milk, and the whey drank going
to-bed ; on the intermediate day, between the fecond
and third bolus of calomel, the fanguine and plethoric
are bled, and phlebotomy is repeated the day before
the eruptive fever is expedfed j during this fever, the
patient is kept as cool as polfible ; balm tea acidulated
with the juice of limes, lemons, or tamarinds, is
freely permitted ; and if the fever runs high, bleed-
ing is repeated pro re nata»

This method fucceeds well with the robull, whofe
fibres are like thofe of Behemoth, and whofe nerves
are like brafs j but I have known others, who, being
of a more delicate make, and their blood of a loofe
texture, fell a facrifice to this method; and others
whofe conftitution was ruined by fuch an indifcrimi-
nate and injudicious ufe of mercury, draftic purges,
and the lancet.

It may be thought unnecefiary to infert my own
particular method, more efpecially as I had oppor-
tunity to inoculate no more than 70 or 80 perfons,
before the practice of inoculation was wholly inter-
di<5ted by the legillature of the colony.

XXV.

J*/jU<js. Trans Vo JILB. TT.Ji>. 20^.

W

[ 205 ]

XXV. An Account of a Balance of a new
ConfruSiion^ fuppofed to be of Ufe in the
W oollen ManifaEiure, By W. Ludlam,

B. D. Fellow of St, John’s College, Cam-
bridge.

Read June 6,Tr T is of confequence in fome branches
JL of the woollen manufadture, that the
thread of which any piece is woven (hould be all of
the fame finenefs. After it is fpun, it is made into
ikains of the fame length, and thefe are forted ac-
cording to the finenefs of the fpinning. The manu-
fadurers ufually difiinguilh and denominate the fine-
nefs, by the number of fkains which go to the
pound; the coarfefi; being about 12 to the pound,
and the finefi: near 60. There is no other method of
forting in ufe, except by the eye; but it requires
great nicety to diftinguifh the fize of threads fo
fmall, and long experience to know by the look
only, how many fkains of any particular fort will'
make a pound. A method of weighing them rea-
dily would fave much time : the machine here deli-
neated is for that purpofe. • It refembles the
beam of a common pair of fcaies ; at one
end of it is a fixt weight, which I call the counter-
poife, at the other a hook : in forting, the fkain to be
examined is put upon the hook, and finks down

mocc

0

[ 2o6 ]

more or Icfs, according to its weight, till the
counterpoife by rifing balances it, and then the
index or cock of the beam points out, on a gra-
duated arch, the number of fkains of that fort,
which go to the pound. A fcale, inifead of the hook,
might be ufed for weighing money, if the arch were
properly divided for that purpofe.

Mr. Roufe of Harborough, many years ago, made
a machine for forting woollen thread upon the fame
principle with this j but as what he did was mohly
tentative, he was not aware of fome confiderable
advantages which the theory points out. For the
machine will not diftinguifli with equal nicety the
fkains of every fize. In Mr. Roufe’s machine, the
divifions were too fmall, and the largefl chanced to
fall at 1 8 to the pound j but it would have been
better if the finer forts had been more accurately di-
flinguifhed, as being of greater confequence to be
well forted, and more difficult to be forted by the
eye only, than the coarfer ones. This machine di-
llinguiffies bed: the yarn of 36 to the pound, one
of the fined forts, as I am informed, in common
ufe, the larged divifion lying between 36 and 37 ;
the other divifions are as large, and the whole range
of the index as much as can be allowed without
other inconveniencies. The theory contains the ne-
cedary rules for finding the angle of the beam, for
calculating the divifions on the arch, and for placing
their larged interval in any part of them.

DlreSiicm

[ 207 ]

DireStions for making the Balance.

IT confifts of a mahogony fland, a fteel beam and
brafs ring for the divifions.

F G H is the triangular bafe of the ftand,
having a fcrew in each angle to fet it level:
into this is dove-tail’d the upright back KK; the
ftandard board L L L is put into a dove-tail’d
groove in the back, and tenonted into the trian-
gular board at the bottom.

The two cocks C C, between which the arbor
of the beam plays, and the ring R R arc fcrew’d to
the ftandard board L L.

The beam A B, with its cock or index E, is broad
in the middle to gain ftrength, and pierced to make
it lighter. It is rivetted on a collet foldered to the
arbor, as clock wheels are. The pivots run in hard
brafs, and have plates of hardened fteel for their points
to bear againfl.

At one end of the beam is the counterpoife A,
confiding of two round pieces of brafs, ferewed to-
gether through an hole in the beam. The other
end of the beam is made thicker for about half an
inch in length, and flit to receive a loop of hardened
deel, which hangs on the deel pin B > on the lower
part of the loop hangs the hook, which holds the
Ikain.

The block of wood N, is ferewed to the dandard
board j the upper part of which is lined with velvet
for the counterpoife to red upon, when the flcain
is taken off the hook ; the brafs pin P is for the
other arm of the beam to bank againd.

The

[ 208 ]

The angle of the beam ACB Is i68° the
radius C A or C B, 6 inches ; the breadth of the
beam in the middle ^ of an inch, at the ends ^ ;
the thicknefs at the end B where it is flit 4.; every
where elfe The length of the arbor i,^. j dia-
meter of the pivets The weight of the coun-
terpoife one ounce avoirdupoife.

The hook, with the loop and fleel pin included,
0,68 avoirdupoife. The diviflon of 50 is at the top
of the ring.

In making the beam, the point of the index E
mufl: be equally diflant from the centers A and B ;
the whole beam and index made fo as to poife itfelf,
and remain at reft in any pofltion, before the coun-
terpoife fleel pin and loop are put on.

The counterpoife being at firil made too heavy, to
adjufl; it, take off the beam, but let the two cocks
and ring remain ferewed on j hang then a fine wire
and plummet on the top diviflon, and with a watch
glafs look through one pivot hole till you fee the
wire againfl the other j turn the ferew G till the
wire bifeds the hole, and the top diviflon is then
perpendicularly over it. Take away the plumb line
and put on the beam and counterpoife j on the loop
hang a weight, which together with the fleel pin
•and loop makes one ounce avoirdupoife j turn now,
by degrees, feme metal off the counterpoife, till the
index points at the top diviflon, and the counterpoife
will be truly adjufted, whether the arms of the beam,
C A, C B, are precifely equal or not : for though
the arms . fhould be nearly equal, it is not neceflary
they fhould be exadly fo, as in fcales.

The

'[ 209 ]

The divifions are fet on the ring by an inftrument
made on purpofe, which will very readily cut them,
tho’ unequal, with great exaftnefs, on any circle large
orfmall.

To prove- the beam, put a weight into the fcalc
(that of 28 to the pound is the beft in this cafe) and
fee if it brings the index down to the proper divifion
on the. ring: if it carries it too far, the angle of the
beam ACB is too great; if the contrary, too little ;
and the arms.C A, C B, muft be fet a little in, or out,
till the angle is right : or the angle of the beam may
be firft found exjjerimentally, by the rule hereafter
given, and the divifions calculated to it, which is not
much trouble ; for having a table ready made for the
intended angle; the alterations in that table occafion’d
by a fmall variation from that angle will be eafily
found by the. rules at the end of the following The--
ory.

When the balance is to be ufed, a weight of of
a. pound avoirdupoife is to be put on the hook: The
fcrew G muft then be turned, till the index E points
at the divifion of 50 : The machine is then properly
adjufted, and the weight may.be taken off, and a
fkain put on.

jtjq 2 Let A CB be a bent lever moveable about
the angular point C, B a fcale at the end of
the arm B, A a counterpoife at the end of the other
arm A; Given the angle of the. lever, the length of
the arms, the refpe<5live weights of the fcale and
counterpoife, to find the pofition of the lever when at
reft.

Produce the arm B C to I,- fo that C I may be to
CB as the weight of the fcale to the counterpoife;

VoL. LV. E e join

'[ 210 3

join A I, turn the lever about till A I is perpendicular
to the horizon, and in that pofition it will be at reft.

For if HB be drawn parallel to I A, and FCH
perpendicular to HB and I A, then CF : CH : Cl;
C B, or as the fcale to the counterpoife ^ that is, per-
pendiculars from the center oftmotion to the lines of
direction are reciprocally as the forces applied, there-
fore in that cafe the forces balance each other.

Cor. Join AB and draw CG parallel to A I, and
A G : GB : : Cl : C B, or as the fcale to the coonter-
poife, therefore G is their center of gravity, which
lying in a perpendicular to the horizon palling thro’
the center of motion, again Ihews the lever to be at
reft.

SCH.OLI u M.

There are indeed two pofitions in which the lever
will be at reft, one when the center of gravity is
above, and another whqn it is belovv the center of
motion ,j the latter only is conlider’d in what fol-
lows.

'Let the arms C A and CB be equal, let the
3- -weight of the counterpoife be fixt, but that
of the fcale variable j then if the fixt line CA
(=:CB) reprefent the former, the variable lined
will reprefent the latter. In the line C I, take C D
=C A and join AD ; thro’ the center C, draw ECK
parallel to AD, which therefore bifedts the angle of
the lever ACB, and the part EC may ftand for the
index or cock of the lever. Let CP be perpendicu-
lar to the horizon, and ECP the angle of the index
with that perpendicular is equal to D AI ; but AC K
is the femi-fum, and DAI the femi-difference of the

angles

[ 211 ]

angles C A I,X I A : Therefore C I -f C A,: G I C A : :
or the fum of the weight of the fcale and counter-
poife is to their difference, as the tangent' of. ACK,
half the angle of the lever, to the tangent of DAI
=ECP, the inclination of the index to the perpen-
dicular when the lever is at reft : and the angles at
A and J, or the inclinations of the arms, will be the
fum and difference of ACK and DAI.

Hence the fcale and counterpoife being given, the
inclination of the index may be found from the angle
of the lever j or the angle of the lever from the in-
clination of the index.

The weight of the counterpoife being fixt, let that
of the Icale vary uniformly ; it is required to find
when the angular motion of the index is greateft.

^ All, things remaining. as before, draw AS- perpen-
dicular to Cl;-, and the variation of Cl will be the
fame as that of" SI (the line CS being conftant) :
For- a, like reafon the variation of the angle DAI is
the fame with that of SAI. Now the variation of
SI, is to that of the arch which meafures SAI, (AS
being radius) asj AD to AS?;: if therefore Clror Sf
flows uniformly, the fluxion ,of S Ad or DAI, or the
angular motion of the index, will be greateft when
Aids leaft, that is, when -AT' coincides with AS, or
when. the inclination of the index is equal to DAS,
or when the:- arm -carrying the fcale is parallel to the
horizon.

The angle DAS is the complement of ADS
(—ACK). or of -half the-. angle of' tlae- leveri
Again.CA:CS: or, radius, to the~. co.-fine. of the
angle«of the lever as. th'e 'counterpoife to the weight

[ 212 ]

of the fcale, when the angular motion of the Index is

Let now the weight of the fcale as well as the
counterpoife be fixt, but into it let there be fuccef-
fively put variable weights or fkains of thread, to be
denominated by the number of them which (at that
lize) go to the pound : Let the weight of thefe fkains
vary at each fucceffive change in fuch a manner, that
the number which goes to the pound may be in-
creafed each time by unity : It is required to find
when the angular variation of the index, in one ex-
change, will be greateft.

All things as before, let C L reprefent the
’ fixt weight of the fcale, L I the variable one
of ths fkain, C 1 that of both together. Call A S, j :
SL, d: put p ■=. one pound, x the number by which

any one fkain is denominated,

confequently

A

weights LI; whence S I =LI-L S = whofe
fluxion (putting the uniform fluxion of x to be unity)
is — - : but the fluxion of S I is to that of the arch

XX

which meafures S A I, as A P to A S% or as A S’+
SP to AS", or as ss-\--~d : ss, that is ss-X-^-d^ ;

ss : : — ^ to the variation of the index fought ; whence

that variation is greatefl when x — ^- — that is

° isX- da

when — or the weight of the fkain =— where-

Fig. 4. if .CA reprefent the counterpoife, and
CL the fcale, join AL and draw AF per-
pendicular

[ 213 ]

pendlcular to it, cutting CL produced in F, then will
LF reprefent the weight of the fkain, and D A F be
the inclination of the index, when its variation is
greateft.

On FL as a diameter defcribe a femicircle,
and let CA intcrfeft it again in a: Join L^,
a F, then will L ^zF be a right angle as well as L AF;
therefore with the given angle of the lever ACB and
given fcale CL, we have the fame maximum FL,
cither with the counterpoife CA, or Qa -, either of
which gives the other j for C A : C L : : C F : C

In like manner, if the angle of the lever,
the counterpoife C A, and F L the weight of
the fkain at the maximum are given, with
Fig. 5, the center A and radius A E — : .1 FL defcribe
a circle cutting B C produced in E and e,
towards C fet off E L and e /, equal to the ra-
dius aforefaid, and either CL or C / will be the
weight of the fcale that will give the propofed maxi-
mum. It is manifeft that^if AE or i- FL is lefs
than AS, the problem is impoffible; therefore the
maximum is limited, and muff be propofed fuch,
that the weight of the fkain in that cafe be lefs than
2 A S.

Example:

Let the femi-angle of the lever be 84° : 03^
the counterpoife one ounce, let the divifion
for 50 to the pound, fland at the top of the graduated
arch perpendicularly over the center of the lever,
that is, let L D =: 44. oz. confequently L C or the
fcale r=CD — LD, orCA — LDr:=i ^

[ 214 }

0,68 oz* then is C S = 0,9785090, h S or d =,
0,2985090, A S. or ^ = 0,2062042, and or

jj , I / AS*

7+‘^‘(=ls

-j- L S) —

LF = 0,440951

oz. and ^ ~ ; therefore the greateft

motion of the index will be when a Ikain of 36 to
the pound is changed for one of 37, and the largeft
interval on the graduated arch will be that which lies
between 36 and 37.

C A : CL::CF : Ca or i : 0,68 : : 1,120951 :
0,762247 ounces, the other counterpoife which gives
the fame maximum.

Let the maximum be afllimed at 36 Ikains
to the pound- exadly, or when F L =
0.4.144444, then is 4 F L or AE = 0 2222222,

and SE (== /aE^AS ' x AE"irXS ) =

0,0828404, whence C L (= CS— .A E S E )

= 0,8391272, and CL (=CS — AE — S E) =,
6,6734464 : if this laft quantity be taken for. the
weight of the fcale, the divifion for 49 in the pound
would fall -at the top of the arch very nearly, there-
fore aflume the divifion of 50 in the pound for the
top, which will make but little alteration in the ma-
ximum, and the weight of the fcale will be 0,68,
the maximum between 36 and 37, as before.

2 A S 0,41 24084, and =,48, 84 19 i

therefore with the angle of the lever and counterpoife
as. before, the maximum, cannoty be higher( than at
48.ikains to the pound. In Mr. Roufe's machine

the

C 215 ]

the angle of the lever was 165“, the counterpoife
1.46057 ounces, the fcale 1,19543 or AS =
0,378024, therefore his machine did not admit of a
maximum higher than between 26 and 27 fkains to
the -pound.

Fig. 3. 7^® one example of finding the incli-

nation of the index, let it be required to find
the angle for a Ikain of 32 to the pound, whofe
weight IS o. 5 ounce; whence Cl- 1.18, CA = j

GI-CA;or 2,*i8 : o, i 8 : : Tang!
A C K = 84* : 03'. Tang. E C P = 38° : 23^'. ^

This rule for the inclination of the index, fuggefis
an eafy way of finding the alterations in it, occafion’d
by any fmall variation in the angle of the lever; othdr
things remaining the fame.

For the change in the Logarithmic Tangent of
EC P, the fourth term in the proportion, is equal to
that made in the Logarithmic Tangent of A CK, the
third term ; the other two terms being the fame.

Take therefore the difference of tfie Logarithmic
Tangents of the two femi-angles, and divide it by
the natural numbers i, 2, 3, 4, &c. fucceffively, and
their quotients among the differences of the Logarith-
mic Tangents, in Tables for each minute, will point
out the quantity of the angle E C P, when the alter-
ation in it is I, 2, 3, 4, 6cc. minutes fucceffively ; by
which means a table may be eafily formed for the
corredion of that firft computed. Suppofe, for in-
fiance, the femi-angle of the lever to be only 84*^ :
inftead of 84 : 03“^, for which a table has been made,
it is required to corred this table, fo as to fuit it to
this femi-angle 84". ^ The difference of the Log.
Tangents of thefe femi-angles is 36,608 ; divide this

by

[ 2i6 ]

by any. of the -natural numbers, for inftance by lo,
the quotient 3660, ftanding among the Tabular dif-
.ferences (in Tables for each minute) at 21° : 50' and
68°: 10',. fhews that when the value of ECP in
the table already made, is either 21°: 50 or 68° : 10.',
JO minutes muft be fubtrafted to adapt it to the lever
whofe femi- angle is only 84° ; and fo of the reft.

The greateft.difference of the inclination of the in-
dex will be when ECP is, 45° : the Tabular differ-
ences being, then the leaft. All this is not indeed ^
quite accurate, but fufficiently fo for pradtice.

To find accurately when this difference is greatefl,
and what that greateft difference is ; add (or fubtradl
as the cafe requires) half the difference of the Loga-
rithmic Tangents of the femi-angles aforefaid, to the
Logarithmic Radius, and it will give the Logarithmic
Tangent of ECP, in that cafe j and the difference
between ECP thus found, and its complement, is
the greateft difference fought. Thus half 36,608
added to lo.ooooooo is 10.001 8304, the Log. Tan- *
gent of 45° ; 7' ; 14' ',4, the inclination. of the in-
dex, when its change by reducing the femi-angle of
the lever to 84°, is greateft, and the quantity of that';
change is 14' : 28", 8,

• A. Table

[ 217 ]

A Table of the inclination of the index, when the
femi-angle of the lever is 84° : 03', the counter-
poife I ounce and the fcale o. 68 ounces avoirdu-
poife, for any number of Ikains to the pound from
10 to 70.

Skain!
the poi

0 /

0 /

0 1

0

/

10

75 • 03

25

52 ; 56

40

20 ; 15

55

8

04

II

73 • 56

26

51 ; 00

41

18 : 02

56

9

30

. 12

72 : 47

27

49 : 01

42

^5 : SO

57

10

53

13

71 : 35

28

46 : 59

43

13 : 41

58

12

13

14

70 : 20

29

44 : 54

44

” : 35

59

13

30

15

69 : 02

30

42 : 46

45

9 : 31

60

14

44

16

67 ; 40

31

40 : 36

46

7 • 30

61

15

55

17

66 : 16

32

38 : 23

47

5 : 32

62

17

03

18

64 : 48

33

36 : 09

48

3 : 38

63

18

08.

19

63 : 17

34

33 = 54

49

I : 47

64

^9

II

20

61

35

31 = 37

50

0 ; 00

65

’20

12

21

60 : 04

36

29 : 20

51

I : 44

66

21

10

22

58 : 22

37

27 : 03

52

3 : 24

67

22

06

23

5*6 : 37

38

24 : 46

53

5 : 01

68

23

00

24

54 : 48

39

22 : 30

54

6 : 34

69

23

52

70

24

41

N. B. According to the report from the committee
appointed by the Houfe of Commons to enquire into
the original ftandard weights, one pound Avoirdu-
poife is I lb. 2 oz. izdwt. Troy; confequently one
ounce is 1 8 dwt. 6 gr. and 0.68 oz. is 12 dwt. 9,84
grains.

F f

VoL. LV.

XXVI. Jn

[ 2l8 ]

XXVI. An Experimental E7jquiry mto the
hlmeral Elaflic Spirit^ or Air^ contained
in Spa Water ; as well as into the Mephitic
finalities of this Spirit, By William
Brown rigg, M, D. F. R. S,

jRead June T is now twcnty-four years fince I
A prefented to the Royal Society feveral
Eflliys on Damps, which were read at the meetings,
and are preferved among the' papers of that moft
learned body. Thofe effays contained a few of the
obfervations and experiments which I had colledted,
for a larger work, on that fubjed: ; and for which, as
opportunity offered, I have fince col levied materials.
And being defirous that fome of my obfervations
fliould be further verified, and more fully afcertained
before they were made public, I therefore declined
the honour of having thofe eflays publifiied among
the Tranfadtions of the Royal Society j efteeming it
fufficient, at that time, to have excited feveral of my
friends, and among thefe, Sir Hans Sloane, and the
Rev, Do(ffor Hales, to communicate to me their fen-
timents on this fubjedf.

In one of thofe effays I had occafion to remark,
that a more intimate acquaintance with Damps
and other mineral Exhalations might lead to a
“ difcovery of the nature and origin of thofe fubtile
“ and volatile principles, which enter the compofition
“ of various mineral waters, and are ffifed their fpi-

“ lit;

5

[ 219 ]

rit ; on which their chief virtues are found to de-
“ pend: and that fome of thofe waters feem to be
“ impregnated with exhalations that nearly refemble
the fulminating-damp 5 which, by its expiohons,

“ is found fo deflrudtive in coal-mines : while other
“ waters are more evidently fiturated with that mod:
‘‘ fubtile and adlive exhalation, which, in many
“ places, perfpires from fprings and lakes, and other
openings of the earth ; or arifes in pits and mines,
“ where it is difcovered by extinguishing flame; and,
“ from its pernicious effedts, in killing all animals that
“ breathe therein,, is known to our iriiners by the
“ name of choak-damp.”

This mephitic exhalation I, long ago, difcovered
to be a particular kind of air, or permanently elaffic
fluid ; and, from various obfervations and experiments
related in the above-mentioned ^ effays, had reafon
to conclude, that it enters the compofltion of the wa-
ters of <Pyrmont and Spa, and of all others vyhich,
from their fharp and pungent tafle, are fliled acidul(B ;
and that it conftitutes the volatile principle of thofe
waters, called their fpirit, on which their prime ver-
tues chiefly depend ; altho’ it hath, hitherto, evaded
the enquiries of the mofl; fkilful chemifts, who have
not been able to retain it in their veflfels j neither have
they difcovered any method of imitating it by their
^rt

In order the more fully to afcertain a fadl of fuch
importance, and to obtain a clearer knowledge of the
nature of this fpirit, I took the opportunity, while
lately at Spa, to make a few experiments on thofe

•* See Extra£t from E% the fourth, which is puhlifhed after

thefe experiments. ,

p £ 2 celebrated

[ 220 ]

celebrated waters ; fuch as my engagements, and the
apparatus that I could readily there procure, would
admit of : The refult of which experiments I now
beg leave to lay before the Society.

Experiment I.

Having filled a common quart bottle with Spa
water at the fountain Pouhon, I took a dried calf’s
bladder, made limber with oil, from which I care-
fully prefied out the air, by twilling it round, then
drawing its orifice over the neck of the bottle, there
tied it clofe, fo as to leave an open communication
between the water in the bottle and the empty cavity
of the bladder, while the external air was excluded
from both. I filled two other quart bottles with the
Pouhon water, and fitted to them bladders in ftke
manner. Thefe bottles Hood fourteen days, during
the month of July, in a warm room ; where I often
examined them, expelling to have feen the bladders
difiended with air arifing from the water. But in this
was difappointed. For, during thofe fourteen days,
I never could difcover any air-bubbles adhering to the
infides of the bottles j neither, from other figns, did
it appear that any elaftic fubflance was feparated from
the water j the bladders, all that time, remaining as
empty as when firfi; tied on. Some of the water, be-
ing then poured from each of the bottles, was found
to fparkle more than when taken, frefii' from the
fountain, and Iboner to emit bubbles on the fides of
the glafl^ into which it was poured : it was perfedlly
clear, and Hill retained its brifk and pungent tafle, to
which was added a tafte from the bladders : but, in

all

[ 221 ]

all other refpeds, it feemed as little altered as it
'would have been, had the bottles, which contained
it, been all the while well clofed with corks.

§2. In order more fully to afcertain the fadts above
mentioned, I filled two of thofe long vials, in which
Frontiniac wine is ufually kept, and two common
quart bottles, with the Pouhon water, and fitted to
them bladders in manner before related ; excepting
that the necks of the bladders were foaked in water,
in order that they might better adhere to the glafsthan
they did when moiftened with oil. The water, thus
excluded from any communication with the external
air, flood feven days in a room, where it was conti-
nually kept lukewarm ; the weather at that time be-
ing excefiively hot, the mercury then ufually {land-
ing from 8 o to 85 degrees in Fahrenheit’s Thermo-
meter. During all that time, the bladders were not
diflended by wny elaflic fubflance arifing from the
water thus heated, but remained as empty as when
tied to the veffels. The water in the two quart bot-
tles, being examined after it had thus flood leven days,
was clear, retained its brifk and fharp tafle, and
feemed in no wife decompounded ; but, when
poured into a glafs, fparkled much, like wine on the
fret. After a third part of the water was poured
from one of thofe bottles, it was imriiediately clofed
with the hand, and fliaken brifkly about for half a
minute j and being then fuddenly opened, the air
mflaed out of it with an explofive noife, and more
than ordinary violence, driving the water with great
force, and difperfing it over the floor in a fliower of
leven yards in diameter.

It

[ 222 ]

It hath been /hewn by Moiif. Mariotte, th.it air is
imbibed, in confiderable quantities, by common wa-
ter, and may again be feparated from it, either by
heat, OF elfe by cold, as in congelation ; or by re-
moving from it the pre/Ture of the atmol'phere, as in
the exhaufted receiver of an air-pump. And Dodfor
Shaw relates that, without any of thefe aids, air
feparates fpontaneoully from the mineral water of
Scarborough, and that, in a few minutes,, he col-
leded into bladders large quantities of air, from bottles
of that water, after the manner attempted in the fore-
going experiments j he alfo relates, that the airfeemed
to arife from the water with fome degree of force,
and continued long in an elaflic date. The fame
experiment was fince tried, by Dodor Home, on the
Chalybeate waters of Dunfe in Scotland •f- j who af-
fures us, that he thus colleded confiderable quantities
of true permanent air from thofe waters j which, with
Dodor Shaw, he conjedures in no refped to differ
from the common air of the atmofphere. And as I
had no doubt of the accuracy and fidelity of thofe
gentlemen in their experiments j and had entertained
an opinion that the mod fpirituous acidulae contained
the mod air, which, it was reafonable to fuppofe,
might be feparated from them in the fame manner
that it was feparable from thofe that were lefs fpiritu-
ous ; I therefore was greatly difappointed in my ex-
pedations, when I could not obtain any air from the
PoLihon water after the manner above related. I did

* See his Inquiry into the Contents, Virtues, and Ufes of
the Scarborough Spavv waters. Part II. Se£t. IV,

t ElTay on the Contents and Virtues of Dunfe Spaw, Edin*
burgh, 1751. page 99, &c.

not.

'[ 223 ]

not, hov/ev6r, conclude, till after repeated trials, that
air does not fpontaneoudy feparate from the Pouhon
water, in inch manner, and in fo fhort a time, as it
is faid to feparate from the Dunfe, and Scarborough
waters ; and that, when excluded from the common
air, it will, for feveral days, bear the greateft heats of
the fummer, ufually found in the ihade, at Spa,
without parting with any of the air, or other princi-
ples of which it is compofed. It is, however, mani-
feft, that, by the heat applied in the above experi-
ments, the Pouhon water was difpofed more readily
to part with its air, or fome other elaftic fubflance,
than it is when taken cool from the fpring : feeing
that, when poured into a glafs, after it had been thus
heated, it fparkled more than when frefh drawn from
the fountain, and flew with more violence when
fliaken in a bottle.

We may alfo hence learn, that when bottles filled
with the aciduhe are broken, in hot, fultry weather,
accompanied with thunder, as Hoffman and others
have obferved them, this accident muff rather pro-
ceed from other caufes, than from the expanfion of
their fubtile mineral fpirit, to which it is ufually attri-
buted. That flalks filled with the Pouhon waters,
are liable to fuch accidents w^hen unfkilfully clofed
up, thofe, who fill them for exportation, have learned
from experience. To prevent which, they fuffer the
flafks, after they are filled, to remain feveral hours
in a warm air before they cork them up. And I
found, that one of thofe flafks being filled to the neck,
at tlie Pouhon fpring, when Fahrenheit’s thermometer
flood therein at 53 degrees, the water had arifen
near three quarters of an inch in the flender neCk of

the

[ 224 ]

the flafk, after it had flood, thus filled, for three
hours, in a heat of 76 degrees ; which rarefadion of
the water, by the common heat of the air in fummer,
was more than fufficient to have broken the flafk, had
it been filled quite full with the water, and immedi-
ately clofed at the fountain.

Experiment II.

I took one of the long Frontiniac vials, which
might contain about 21 ounces avoirdupoife weight
of Spa water, and which had flood feven days, in
exceffive hot weather, filled with Pouhon water, with
a bladder fitted to it, as related in the foregoing ex-
periments. The vial thus filled was placed in a
copper vefTel, fo as to be immerfed in water to two
thirds of its height ; and to the neck of the vial was
fitted a kind of truncated cone, of fpiral wire, to keep
the bladder in an ered:pofition. (SeeTAB.VII. Fig. i.)
The copper vefTel was fet over a flow fire, and the water
therein heated to as great a degree as I could well
endure with my hand; which 1 found to be about
1 10 degrees, according to Fahrenheit’s fcale. In
this degree of heat, large bubbles of air Toon began
to arife to the top of the vial, forcing up with them
final! particles of water, which bedewed the fides of
the bladder two inches, or more, in height. The vial
being taken for a few moments out of the bath, the
more exadlly to view this kind of ebullition ; very
minute bubbles were obferved to be formed, in the
middle of the water, near the bottom of the vial ;
and from thence afcending with a rapid motion, and
in continued flreams, gradually to enlarge, until they

flew

[ 225 ]

flew off, with a boiling motion, and conflderable force,
from the furface of the water ; which, by its dilata-
tion, arofe into the bladder. The vial was kept, in
this moderate heat, two hours j during which time,
the bladder became more and more diftended with
the air, or other elaflic fubftance, expelled from the
water ; which was obferved to acquire a muddy
whitenefs in proportion as the elaffic fubffance was
expelled from it. The bubbles, after about an hour
and half, gradually leffened in number and fize ; and,
at the end of two hours, almofl; difappeared. The
heat was then gradually increafed for another hour ;
at the end of which time the water in the copper
veffel began to boil. And in this boiling heat the
vial remained another hour 5 when it being judged
that all the elaflic fubffance contained in the water
was expelled from it, the vial was removed from the
fire, after it had continued in the water bath four
hours. From the time that the heat of the bath was
increafed, the water in the vial grew more and more
turbid 5 the earthy particles were formed into fmall
maffes, which were driven about by the heat. To-
wards the end of the operation, thefe earthy maffes
cohered into larger flocculi; and from white became
of a yeilowifli colour. Thefe flocculi grew larger as
the water cooled, and flowly fubfided to the bottom
of the vial. While the water in the vial was yet
warm, the elaffic fubffance that had been expelled
from it was tied up clofe in the bladder, and then
removed from the vial. The water in the vial, be-
ing corked up, was fuffered to ffand till perfectly
cool. Being then examined, it was found to have
got a taffe from the bladder j but was quite vapid,
VoL. LV^. G g having

[ 226 ]

having entirely loft its diftinguiftiing brifk, fharp, fer-
ruginous tafte, as alfo its power of ftriking a purple
colour with galls. The elaftic fubftance contained in
the bladder, when taken from the fire, appeared
equal in bulk to half a pint of water. It leflened
confiderably in the cool air, for fome days after it had
been thus extra^fted, but did not afterwards feem to
diminifli much in bulk, tho’ kept for a month in the
bladdef.

§ 2. I had feveral times occafion to reppt the
above operation 5 and found that all the elaftic fub-
ftance could fcarce be expelled from frefli Pouhon
water, by the above degrees of heat, in a much
fhorter time than that employed in the foregoing ex-
periment. For a common quart flafk of this water,
having been kept three hours in a water bath, heated
to as great a degree as I could well endure with my
hand (which might be about 130 degrees, accord-
ing to Fahrenheit’s fcale), and having afterwards
ftood twenty-four hours before the bladder was re-
moved from it j when opened, was found turbid, but
had not depofited all its earthy particles, and ftill re-
tained a little of its briftc tafte. Another flaftc of the
fame water, fitted in like manner with a bladder, was
kept two hours in a fcalding heat (of about 160 or
170 degrees of tbe fame thermometer), fo that moft:
of its elaftic fubftance feemed forced from it ; yet,
when the flafk was opened the next day, the water
ftruck a purple colour with galls, and had not quite
loft its ftiarp fubaftringent tafte ; and after about a
third part of this water was poured out, and the reft
fliakcn brifkly in the clofe flalk, and then fuddenly

opened.

[ 22? ]

opened, an elaftic fubftance was ftili difcharged from
it, with a confiderable explofion.

From thefe experiments we learn, that the Pou-
hon water contains a large quantity of a very fubtile,
light, and permanently elaftic fluid, or of true mi-
neral air j and that this aerial fluid is clofely united
to the other principles of which this water is com-
pofed.” For, from Experiment the Ifl, it appears,
that when this water is excluded from all communi-
cation with common air, and at the fame time liberty
is given to the aerial fluid contained therein to ex-
pand, and to fly from it, with the fame facility as
from the water in an open veffel ^ yet, under thefe
circumftances, this elaftic fluid does not exert its
power of expanficn, but remains fo firmly united to
the other principles of this water, that it does not
feparate from them when agitated, for feveral days,
with a heat of eighty degrees of Fahrenheit’s ther-
mometer. While, therefore, this water is in its na-
tural ftate, and is not adted on by any other body,
the aerial principle remains quiet ; and, with the
other principles, feems equally dilTolved in the watery
element. It is not, therefore, then confined by any
external force, like the air of beer, cyder, champaign,
and other huffy liquors, which, while they are clofed
in bottles or other veffels, by their fermentatory mo-
tion, generate more air than they can imbibe and
keep diflblved j fo that much of the air, fo generated,
is pent up in a confined ftate, and continually preffes
on every fide, until a vent is given it, and then it
ruflies out with violence.

But, from the foregoing experiments, it appears,
that this fubtile elaftic fluid, while it is affociated with

G g 2 the

[ 228 ]

the other principles of the Pouhon water, and Is kept
from contadl of common air, and of fuch other bo-
dies as are found to decompofe this water, it remains
in a quiet difTolved flate, intimately mixed with the
other principles of which this water is»compofed,
and fo clofely joined to them, that it is not readily
feparated from them by a lefs heat than that of loo
degrees of Fahrenheit’s thermometer ; which heat it
endures for feveral hours, before it is entirely detached
from its union with them. It alfo appears, from the
above experiment, that in proportion as this mineral
air is feparated by heat, in the fame proportion the
more grofs earthy parts of the water feem alfo to fe-
parate from it ; and that as the mineral air is thus
entirely expelled, the water is then wholly decom-
pofed, its metalline and earthy particles having fub-
fided, its more volatile and elaftic principles being
exhaled, and nothing remaining in the water, fave
only the fmall portion of alkaline and neutral fait,
which is found diffolved therein.

It may here be noted, that the numerous analyfes
of thefe waters, which have been attempted in re-
torts and receivers where the water was expofed
with a large furface to the common air, the eladic
fubftance feems to have been extraded from the wa-
ter more readily, and with lefs heat than in the pre-
ceding experiment ; and pellicles have lometimes
been obferved -f* on the water in the retort, as on the
fame water expofed to the open air ; the caufes o-f
which pha^nomena will be explained hereafter.

* See De Prefieux, Chrouet, Le Dran, Limbourg, Lucas, 5ic.

t Sec De Preffeux.

Experiment

[ 229 ]

Experiment III.

In order to afcertain the quantity of air contained
in the Pouhon water, a Frontiniac vial was there-
with filled at the fountain, on a clear morning, when
the wind was eaflerly, and a flrong fwine’s bladder,
well freed from air, was immediately fitted thereto ;
all the air was then carefully expelled from this water
by the heat of the bath, after the manner related in
the foregoing experiment. The vial, with its con-
tents, as foon as cold, was placed, in an inverted po-
fition, over a ciftern of common water (as in Fig. 2.)
fo that the air, which had been expelled from the
water, afcended to the upper part of the vial, while
an equal bulk of the water contained in the vial
defcended into the bladder. When all the air had
afcended into the vial, the height at which the water
flood therein was marked with a diamond.. The
bladder being then removed, the vial was carefully
clofed with a cork, and then taken from the ciflern ;
and the air which it contained was kept therein, until
it was wanted for the ufe which will be mentioned
hereafter.

As foon as the vial was emptied of the air and
water which it contained, and had been exactly
weighed, it was filled a fccond time with the Pouhon
water, which was found to weigh twenty ounces, fe-
ven drachms, and fourteen grains, apothecaries weight.
The vial was then emptied to the marks at which the
•water had flood therein, when in an inverted pofition ;
and the water remaining in the vial (which now
filled the fpace that had before been occupied by the

air

[ 230 ]

air extradled in the above-mentioned procefs) was
found to weigh eight ounces, two drachms, fifty
grains. So that the bulk of the air extradled from
the Pouhon water was to the bulk of the water from
which it had been extradled, nearly as 84 to 204.
Or, if we choofe to reduce the above quantities into
cubic inches, and allow a cubic inch of water to
weigh 265 grains, we fliall find, that in this procefs
cubic inches of air were extradled from
37445 cubic inches of the Pouhon water.

From the above experiment it appears, that a very
large quantity of air is contained in the Pouhon wa-
ter : and a way is pointed out whereby the propor-
tion of the bulk of air to that of a certain quantity
of water, from which it had been extradled, may be
exadlly determined. Altho’ this proportion mu ft vary
confiderably in many waters, according to the weight
and heat of the atmofphere, or the drynefs or moi-
fture of the feafon, at the time that they are taken
from the fountain j and will alfo vary with the dif-
ferent degrees of expanlion of the atmofphere, at the
times that the different quantities of air are meafured j
I do not, therefore, give the above proportions for
fuch as always hold ; neither do I ^ert that they
moft commonly take place. I rather fufpedl the
contrary j and, from other trials, am apt to believe,
that a larger proportion of air is ufualiy contained in
the Pouhon water, than that which I obtained in
the above experiment. For, when a boiling heat
was ufed, the necks of the bladders were apt to fliri-
vcl, and became liable to crack on the leaft motion ;
lb that it was difficult to confine the air in them.
Flad I had an opportunity at Spa of profecuting this

experiment

3

[ 231 ]

experiment farther, I Ihould have attempted to have
extracted all the air by a milder heat of about no
degrees, in vials inverted in the water bath ; fo as
that, while the air arofe into the vials, an equal por-
tion in bulk of the water might have been received
into bladders fitted to them ; or Ihould have made
ufe of other methods, which I fhall have occafion
hereafter to defcribe.

Experiment IV.

I took a glafs receiver, of a cylindric form, near
54- inches high, and 34. inches in diameter, which
contained 25 oz. 150 grains of water, Troy weight;
or in meafure 45-4-44 cubic inches, according to the
above calculation of 26;^ grains of water to the cubic
inch. This receiver being immerfed in a ciftern of
water, was there turned, with its mouth downwards,
and then raifed, thro’ a hole in a board fitted to the
top of the ciftern, as in Fig. 3. The receiver
was there firmly fecured with wedges, in fuch man-
ner as to continue full of water, the lower part of it
remaining immerfed in the water of the ciftern.

I then took a Frontinijic vial, which contained nine-
teen ounces five drachms of water : this was filled
with frelh pure air, by emptying it of the water in
a cool open place, and then ftopping it with a cork.
The vial, thus filled with air, was placed, in an erect
pofition, under the receiver; and the cork being ta-
ken out, the air afeended into the receiver, as it was
forced out of the vial by the water rufliing into it.
Into this air a moufe was conveyed, by placing it on
a round piece of cork, and plunging it quickly thro’

[ 232 j

the water into the receiver, in which it floated on
the cork. In this air it lived for an hour in great
cafe, breathing with freedom, and diverting itfelf,
while wet, w'ith drying its face and head with its
paws, like a cat. After having thus lived an hour
in this clofe prifon, it was taken out of it, thro’ the
water, by the fame way that it had been conveyed in,
and did not feem to have received any harm by this
confinement, and by palling thro the water ; as after
twenty-four hours, by the help of proper food, it
was found as lively and adlive as it was before it had
been thus treated.

§ 2. A fmall bird, viz. a green wagtail, being
treated in the fame manner, continued for an hour
in the receiver in the fame quantity of frefh air. It
breathed three quarters of that time with great eafe,
but, towards the end of the hour, quicker, and with
fomc ftruggle. Soon after it was taken out, it grew
lively, and again breathed with the fame freedom as
before the experiment.

Our countryman Mayow afierts, that a fourteenth
part of the air, in which thefe fmall animals are con-
fined, is confumed by them before they expire. His
experiments merit to be further verified. The ex-
periments here related, which differ in feveral refpeds
from thofe of Dodfor Mayow, feemed neceffary, in
order to flaew that thefe fmall animals can live corn-
mod ioufly, for a confiderable time, clofely confined
in the above-mentioned quantity of pure air; and
that they fuffer no harm in paffing into and out
of the receiver.

By the way, I beg leave to remark, that by filling
vials with dry fand, infiead of water, here uled, and

emptying

[ 233 ]

emptying them In the Grotto di cani, or other deadly
caverns, thofe mephitic exhalations (of which fomany
of theantients,as well as the moderns, have fo much and
fo varioLifly written) may be colledled, and conveyed
to a great diftance j and, when duly examined, will,
doubtlefs, be found true, permanent, mineral air, of
that kind known to our miners by the name of
Choak-damp. Of which fort the air of the mi-
neral water of Spa appears alfo to be, from the fol-
lowing experiment.

Experiment V.

I took the air which, two days before, I had ex-
trailed from the Pouhon water, as related in Expe-
riment III. This air I emptied out of the vial into
the receiver fixed in the ciftern, in the manner de-
fcribed in the foregoing experiment. Into the fame
receiver I alfo emptied a bladder of air, extraded:
from the Pouhon water four days before. Which
two parcels of mineral air filled as much of the re-
ceiver as had before been filled with common air, in
the laft-mentioned experiment. Into this mineral
air, thus included in the receiver, the moufe was
conveyed, which had been employed on the pre-
ceding day in the foregoing experiment. On palling
into this air, it immediately held up its head very high,
and turned it on every fide ; and, in four or five le-
conds, without any difficulty of breathing, or other
ftruggle, fell down on one fide, and remained with-
out motion. Half a minute after, it was taken out
of'the receiver, and placed on a table before a win-
dow in the open air, where it lay four hours with-
VoL. LV. H h out

[ 234 ]

out (hewing any fign of life, being quite ihff and
dead.

Two other lively mice were fuccedively treated
in the fame manner. The appearances in thefe were
exadly the fame as in the firft. Both of them, after
they had been in the mephitic air a few moments,
fell down motionlefs, and were taken out dead. And
tho’ the laft of the three was taken out of the receiver
as foon as pofiible after it ceafed to move, yet it never
after fliewed the leafl fign of life. The fame ex-
periment was, fome days after, tried in air frdh
extraded from the Pouhon water, on two of the
finall birds mentioned in the foregoing experiment ;
in wdaich air they, in like manner, alfo foon expired.

By way of Scholia to the lafi: experiments, I beg
leave to refer to what I have written concerning the
mineral elaftic fpirit of the acidulae, in my fourth
Ellay on Damps, and other Mineral Exhalations,
which is in the poflefiion of the Royal Society.

I fliall not now detain the Society any longer with
more of my experiments ; but, if thefe fliould be
thought worthy of its notice, fiiall, hereafter, com-
municate other methods of extricating the air from
the Pouhon water, as well by heat, as by other me-
diums 5 and, from proper obfervations and experi-
ments, fhall endeavour to explain the modus of the
union of this fubtile elaftic fluid and the other prin-
ciples with which it Is combined in thefe waters, to-
gether with the relation that it bears to common air,
and to feveral other bodies. Which obfervations and
experiments may, perhaps, be thought worthy the
attention of thofe who hereafter may make enquiries
2 concerning

[ 235 ]

concerning the nature and virtues of thefe, and fe-

veral other mineral waters.

W. Brownrigg,

Whitehaven, i8 May, 1765..

(

• . Explanation of Tab. VII.

Eig. I. A Frontiniac vial filled with Pouhon water, ,
with a bladder and’ fpiral wire fitted there-
to, as defer ibed Exp. ii..

Fig. 2. Another of the fame vials placed in a ciftern, ,
in an inverted pofition, as related Exp. iii.

Fig.. 3. A glafs receiver, of a cylindric form, fixed
over the ciftern (AA) in an inverted fitua-
tion, fo as to remain full of water, until
air is transferred into it, from the vial (B), ,
or from other veffels, for the ufes men-
tioned in Exp. iv. and v.

Fig. 4.. A board, of a femicircular . form, fitted to
the top of the ciftern (AA), with circu-
lar holes, and niches, for the vials, and
receivers ufed in the lafl-mentioned expe»-
riments. .

H.h 2.

Extrooi

[ 236 ]

ExtraB from an Efay^ entltuled. On the Ufes of a
Knowledge of Mineral Exhalations when applied
to dilcover the Principles and Properties of Mineral
Waters, the Nature of Burning Fountains, and
ofthofe poifonous Lakes, which the Ancients called
Averni j which was read before the Eoyal Society in
April 1741, and to which the Author refers in the
foregoing Experiments.

A More accurate Hiftory of fubterraneal Exhala-
tions would alfo further contribute towards the
improvement of the Medical art, by leading us to a
more perfedl knowledge of the genuine principles of
feveral kinds of mineral waters j and by teaching us
how to apply them rightly, and how to account, in
a rational manner, for their operations and effedts
upon the human body.

For it hath long been obferved (i), that the chief
energy and virtue of feveral mineral waters doth not
xefide in the more grofs, faline, earthy, or metalline,
particles, which they imbibe in their fubterraneous
paffages, but in a far* more fubtile and volatile prin-
ciple whei'ewith they long remain imbued when
clofed in bottles ; but when they are expofed in open
veffels, this volatile principle foon takes its flight,^
leaving the waters dead and inert, and deprived ot
their former falutary qualities.

This fubtile and fugitive principle Is, therefore,
fitly called the Spirit of mineral fountains. To ex-
trad which fpirit in the form of a liquid, many have

j[i) Vide Bechcri Phyfica Subterranea, fe£l. il. cap. iv.

employed

[ 237 ]

employed much time and ftudy, and others have
alfo endeavoured to feparate it from the aerial element
of mineral waters j but all thefe attempts have proved
vain and fruitlefs, fince it is plainly incoercible, and
can fcarce be condenfed into a vihble body.

We, therefore, readily fubmit to the opinion of
Dr. Fred. Hoffman, who, by many folid arguments
and judicious obfervations, hath fliewn (2), that this
fpirituous principle of mineral waters is an exceeding
rare and fubtile body, endowed with an expanfive
quality, or a kind of elaftic aerial fluid ; and there-
fore cannot be rightly diflinguifhed from the air of
mineral waters, as if they were two different principles.

This moft delicate and fubtile aerial fpirit of foun-
tains, the fame "judicious author obferves, is as it
were the life of feveral minerals, preferving them
from corruption, animating them with a lively fpark-
ling and briflenefs, and infpiring them with wonder-
ful and excellent virtues, which they exert in re-
moving many obflinate diforders ; and hath hitherto
remained inimitable by art.

Neither is there any reafon to doubt that bodies fo
extremely rare and fubtile, as are the fpirits of foun-
tains, are capable of imparting fuch remarkable qua-
lities to mineral waters. The great power and force
of adlion, wherewith many kinds of mineral expira-
tions are endowed, fufficiently appears from the ob-
fervations (3) before related. And thofe who arc
unacquainted with the wonderful efficacy of exhala-

(2) Fred. HolFman, de aquis mineralib, indagandis, § 16. &
Id. De Convenientia Elementor. & Virium, &c. § xix.

(3) Helmont, Complexionum atque Miftionum Elementalium

figmentum, § 43.

tions.

[ 23.8 ]

tions, and their manner of operating upon - the hu-
man body, may receive ample fatisfa^ion from Boyle
in his treatife of Effluvia. The fagacious Helmont,
therefore, very judicioufly recommends a more fre«
quent ufe of thofe furious incoercible fpirits, and vo-
latile fumes, in the practice of phyfic ; juffly obferving
that no other medicines operate fo fuddenly and fo
powerfully upon the human body (4).

Neither ought we^ becaufe thofe fpirits of fountains'
are flatulent and elaflic, from thence to infer, that
they agree with common air in every other refpedl,
as many are apt to imagine. For corpufcles, which
differ extremely in magnitude, denfity, and figure,-
may all be endowed with one common repulfive
quality. And it is highly probable that the elafiiic
particles, which are emitted from various kinds of
denfe bodies, do thus vary one from another ; and
that they oft-times compofe elaffic fluids, which differ
as mucli from each other, as thofe bodies differ from
which they are produced. Thus the air of peafe,
which is inflammable, feems to differ as much from
the mephitical air of oak, which* cxtinguifhes flame,
as thofe two vegetable fubffances difler between
themfelves. So that two elaftic fluids, altho’ they
both poffefs a repulfive quality, may yet in their other
qualities differ as much as inelaftic fluids are found
to differ i as water, for example, differs from oil of
vitriol. The particles, therefore, of denfe bodies,
when they are feparated from each other, and affume
a repulfive quality, are not always reduced to com-
mon air, but to different kinds of elaftic fluids,

(4) In the preceding Eflays on the Fulminating-damp, and
the (Jhoak-damp.

wliich

[ 239 3

•which frequently retain the qualities of the denfe bo-
•dies from which they were generated ; and which,
by being reduced to an elaftic ftate, become more
a^ive and penetrating, and operate much more fud-
denly and violently upon the human body; as the
fumes of quickhlver, and the vapour of water, by
their effedts, do fufficiently prove.

Now, as thefe fubtile and elaftic fpirits do fre-
quently exert very fudden and violent effedls upon
the human body ; and entering the compofition of
mineral waters, often endow them with excellent
virtues ; it may, therefore, be ufeful to examine the
origin of thofe fpirits which are found in fountains,
and to conlider in what manner water becomes im-
pregnated with them as it pafTes through the bowels
of the earth. To determine which queftions, thofe
obfervations will greatly contribute, which we have
already given concerning the generation of the fire-
damp, and its lodgment in the cavities of earth. For
as the fire-damp is generated from fulphureous and
ferruginous fubfiances, and is often clofely pent up*
with water, and intimately (5) blended therewith in the
fubterraneous cavities ; its particles, therefore, being
impelled by their own elaftic prelTure into the pores
of the water, will be diflblved therein, after the fame
manner as 1 have before fiiewn they may be diflblved
therein by art. And in like manner, water will be-
come impregnated with thofe other kinds of air and
mineral exhalations, which are lodged in the fubter-
raneous cavities thro’ which it palfes. The fubter-
raneal damps and mineral fpirit of fountains feem,

(5"^ See ElPay on the Fulminating- damp,

therefore,

[ 240 ]

therefore, exatflly to refemble each other both In-
their nature and origin. And of this opinion is the
above-cited Fred. HorFman, who feems in every
refpedl qualified to have advanced the knowledge of
mineral waters to its higheft perfedion, had he been
furnifhed with a more accurate hiftory of mineral
exhalations.. By means of fuch an hiftory, he would
probably have been enabled to diftinguifli the fpii its
of mineral fountains into their different kinds, which
he now feems to confound together, as if they were
alike in every refped. Altho’ ’tis not improbable,
that as there is a great variety of fubterraneal exha-
lations, fo alfo there may be various kinds of mineral
fpirits ; and that water may be capable of imbibing
levcral kinds of thofe exhalations which it meets
with in the bowels of the earth. The Rev. Dodor
Hales, in his Statical Elfays, and Dodor Shaw, in
his Inquiries into the Nature of the Scarborough Wa-
ters, have lliewn various ways whereby thefe aerial
fpirits may be extraded. If, therefore, the fpirits
extraded from different mineral waters, by the ways
which they dired, were carefully examined, and
were compared with each other, and with the differ-
ent forts of mineral exhalations which are found in
the earth, we might, perhaps, more eafily diftinguifli
their feveral kinds, and more exadly difcover their
refemblance to the feveral forts of mineral exhalations,
than by any other method which could be put in
pradice.

But, without having recourfe to experiments of
this kind, we may from other oblervations conclude,
that the fpirit of thofe waters which are called Aci-
dulae is nearly related to the choak-damp, or ftith,

found

. [ 241 ]

found in the coal-mines, and in various other parts

For, fubtile mephitic fpirits have frequently
been obferved to expire from the earth in parts ad-
jacent to many of the acidulce, and to produce the
fame effedls upon animals and other bodies as the
ftith or choak-damps, or as the fpirits of the Grof/o
di Cani in Italy, of which, and others of the like na-
ture, Leonardo di Capoa hath largely treated. Thus
the learned Dr. John Philip Siep hath communicated
to the Royal Society (6) a very accurate account of
a grotto of this kind, which he difcovered near the
fountains of Pyrmont. Another grotto of the fame
fort Pechlinus takes notice of, nigh the acidulje at
Swalb in Germany (7). And the learned Hoffman
was informed by a peribn of credit, that a fountain
in the Black Foreff, in the dutchy of Wurtemburgh,.
which had flowed a long time, was fuddenly deprived
of all its taffe and virtue, by reafon that in the neigh-
bouring parts a mineral and fulphureous vapour im-
petuoufly burff out of a chafm which was made in
the rock j but this chafm being clofely ffopt up, the
fountain again obtained its former virtues, (8).

And that the acidulae are really impregnated with
a mephitic exhalation refembling the choak-damp,
fome of thefe fprings (as thofe at Pyrmont) do
plainly difcover by their deadly effeds upon ducks
fwimming upon their furface (qL

(6) Philofoph., Tranfaaions, N° 448. pag. 266.

(7) Pechlinus, lib. iii. Obf. 44.

(8) Hoffinan, De Pfincipiis & Virtutib. prascipuor. Germaniot
Medicator. Fontium, § xxxv.

(9) Dr. Philippus Sicp. Ibid.

Yol. LV. I; i

To

'C 242 j

To the fame fpirits may alfo be attributed the
;power which the acidul* poffefs, of caufing a giddi-
-uefs of the head, heavinefs, and drowfinefs, as from
intoxicating ‘liquors.

The brifk and pungent tafte of the acidulae is alfo
a further evidence that the mineral air which they
.contain is nearly related to the choak-damp. For
-from this brilk pungency of tafte, thefe fpirits appear
•to relemble the air which is generated from beer and
other liquors by fermentation. But the air of fer-
menting liquors is by numerous experiments difco-
vered to be a deadly poifon when applied to the lungs,
and the external parts of the body, adling chiefly
upon the nervous fyftem, and inftantly killing thofe
animals which breathe it, exadly in the manner of
the choak-damp. Yet neverthelefs this air, when
taken inwardly in a convenient quantity of a liquid
vehicle, is found to have wonderfully exciting and
reviving qualities, of which the cafe of Cornaro affords
us a remarkable inftance (10),

In like manner, the elaftic fpirit of the acidulae
feems to have a great fhare in the admirable effedls
which thofe waters exert upon the human body. For
being exceedingly fubtile, penetrating, and adive, it
feems fitted to pervade the whole body, and to force
a paflage through the minuteft vefiels j by its mild
and gentle ftimulus, to corrugate the fibres, increafe
their elafticity, and excite them to motion ; by its
expanfive quality, to rarify and as it were fpiritualize
the blood, and dilate the velfels. By thefe feveral

(10) See Difcorfo terzo della Vita fobria di SIg. Luigi Cor-
naro, pag, 87.

ways,

[ 2+3 ]

ways, therefore,^ it may greatly contribute to
ftrengthen the folids, to accelerate the motion and
circulation of the fluids, and to warm and invigorate
the whole animal' frame. So that to thefe fpirits
feem in a great meafure owing, the virtues which the
acidul« poflefs, of attenuating the humours, break-
ing their unnatural concretions, and powerfully open-
ing obftrudions j of provoking the appetite, aflifling
the digeftion and concodion of the aliment, and
facilitating all the natural fecretions and excretions ^
of the body..

hi

XXVIII. Ex-

. i w i . «

[ 2++ ]

XXVII. ExtraB of a Letter from :Mr.
Benjamin Gale, a Phyfician in New
England, to John Huxham, M, L>»
F. R, S. concerning the fuccefsful Appli-
cation of Salt to Wounds made by the
Biting of Rattle Snakes ; dated at Kil-
lingvvorth in Conne<flicut, 20 - Auguft,
1764.

Read June 13, 'T' Have been difappointed in procuring a
X fnake, to make experiments in

expelling the poifon, particularly the efficacy of fea
fait ; but have now the fatisfadtion to acquaint you,
that having defired Mr. Porter, an eminent furgeon,
and a gentleman of worth and probity, to make en-
quiry, whether the efficacy of fea fait could be pro-
perly attelled ; he this day informs me, that a perfon
was wounded by that lerpent, about the beginning
of this month, juft above his ftioe. The teeth of
the ferpent, upon examination by the probe, he
found to have entered near half an inch. The perfon
bitten immediately made a ftrong ligature above the
wound, and in lefs than two hours came to Mr.
Porter’s. The leg and foot below the ligature were
much fwelled, and the patient grievoufly affedted
with a naufea. Mr. Porter made immediately a deep
fcarification, rubbed it well with fait, applied a doffil

of

[ 245 3

of lint molftened over the fait and fcarlfi cation, and
difmilTed his patient, who the next morning re-
turned. The ligature was continued, neverthelefs
the tumefadion was greatly abated ; the dreffing be^
fore applied was renewed, and the perfon recovered
without any further application. This perhaps, to-
gether with the former inftance may ferve to
eftablifo the truth of its efficacy.

* This was a perfon, under the care of Mr. Strong, a fur-
geon in New England, who in the year 1761 was bitten by a
rattle fnake in the left foot, between the great toe and the next.
He immediately perceived a ficknefs at the ftomach, which con-
tinued fome time. Scariftcadons .were diredlly made, by cut-
ting the fkin, pulled up by an awl, formed into a hook for that
purpofe. The firft application was fine fea fait, which was
plentifully fprinkled and rubbed in and about the wound and
fcarification. Thefe were done in the fpace of about two mi-
nutes after the wound was made. Then a puldce made of
, burdock-root pounded, and mixt with a large portion of fea
fait, was applied to the wound, and another of blood-root was
bound about his leg a little below the knee. In the mean time,
the patient took inwardly faffron and water, in which was
‘fteeped the bark of white afh, which caufed him to vomit. The
confequence of the wound was a tumefadlion, which was
greateft in the foot, but extended to the knee, where it ended.
‘ After thefe applications, nothing remarkable was obferved in the
wound. They were continued for two days, and the patient
perfeilly cured. Mr. Strong fuppofed the fait to be the princi*
pa! ingredient, which efFe^ed the cure.

XXVIII. Ex-

[ 246 ]

XXVIII, ExtraBs of three Letters of Sir
F. H. Eyles Stiles, F. R. S, to Daniel
Wray, Efq\ F. R, S, concer?nng fonie
7iew Microfcopes made at^ Naples, and their
life in viewing the fmalleft OhjeBs.

Naples, nth Auguft, 1761,

Dear Sir,

Read Nov. 7, ✓^Aptaln Hood, of the Veftal man of

of war, having failed from hence for
Leghorn the 3d inftant, I took the opportunity of
fending you by him a fmall Box, put into my hands
by Father di Torre, containing four of his fpherical
GlalTes for the Microfcope, which he had defired
me to tranfmit to England, as a prefent from him
to the Royal Society, which he hopes will prove as
acceptable as he wifhes. The diameters of the
glades, and their magnifying powers, are as follows.

Clafs. Dratneter. Ma|;nifying powers,

ift. Near two Paris points, 640 times, and upwards, in diameter,

ad. One Paris point, . jzSo

3d, One Paris point, 1280

4th, Half a Paris point, 2560.

%

The paper, which enclofesthe laft of thefe,has the
following fuperfcription.

« Igne puriffimo generatum incredibili patientia
. **' cucullis orichalceis inclufum globum primum 6c
unicum diametri punfti dimidii Parifienfis, qui

‘5 objecStorunx

Z

t 247 ]

objedlorum diametrum auget 2560, inclyfte Soci-
etati RcgiiE Anglicanas Jo. Maria de Turre
D.D.D.”

I was to have accompanied this advice with fome
inftrudlions for the management of the glafTes, and
alfo with fome minutes I took lately of a few ob-
fervations, which, at Padre di Torre’s requeft, I made
with him of the globules of human blood, for the
confirming of the difcoveries in his book lately tranf-
mitted to you by Sir James Gray : but the Captain’s
departure being fudden, and the above-mention’d
papers not yet prepar’d, I thought it beft not
to lofe the opportunity I had of fending you the
glafTes, and advifing you immediately thereof ; dired:
flipping from hence to England being fcarce. The
other papers I. fhall tranfmit you by the poft, as foon
as Father di Torre has furnifhed me with his dU
redlions for the management, &c.

In anticipation of the minutes I propofe fending
you concerning the human blood, I can’t help taking
the opportunity of obferving to you, that this mofl
worthy Father is fo efteemed here for his excellent
^nd amiable private charader, that there can be no
joom for the leaft fufpicion of the veracity of the
•remarks in his book j and in refpedl: to his care and
exadlnefs in making his obfervations, I have had fuch
experience of it in feveral meetings he has favoured
me with for the purpofe, that I fhould in any cafe as
readily rely on his eyes as my own, and indeed with
better dependence; as, by the habit of obferving,
he is enabled to pronounce immediately with cer-
tainty upon appearances, that coH; me, much time and
infpedion to examine and comprehend.

I entreat

[ 248 ]

I entreat you will prefent my relpedls to the Royal
Society j and that you will believe me to be,- with
great truth and efteem,

Dear Sir,

Your moft obedient
humble fervant,

F.. H. Eyies Stiles,.

^'T^HESE glalTes are fo fmall, that the diameter
of the higheft magnifier among them is but
half a Paris point, which is, if I miftake not, no
more than of an inch, the point being of a
line, and the line of an inch.

The great difficulty, with refped to thefe glafies,
confifts, as Padre di Torre tells me, in- the handling
them, and the getting them into the little brafs foc-
kets, prepared for their reception. The making
them in his method is foon done ; but they mufi be
focketed before he can examine to fee whether the
fiame of his lamp, which produces them, -has fuc-
ceeded to the perfedion he wiflied j that is, whdher
they be perfedly fpherical, and without flaw, fpeck, or
other accident, which they, are fo liable to, that he
makes many, before he produces one to his mind : and
indeed he lets fo little value upon them, till he has
proved them by the vifion of fome objed, that if one
of them, when he has made it, flips out of his little
pincers before it has been proved, if he cannot re-
cover

[ 249 1

cover it at once, he often makes a new one, rather
than give himfelf the trouble to fearch for it.

The high magnifier I have been fpeaking of in-
creafes the objedt 2560 times in diameter; it is the
firft and only one he has ever fucceeded to make of
that high power; fo that this prefent is a curious one.

S 1 R,

Read Nov. 14, A Greeable to the promife in mine of
*7^5* the paft, I enclofe you Father

di Torre’s inftrudlions for the ufing of his glaffes ;
and I fubjoin an account of three feveral obfervations
1 made with him, at his requeft, of the human
blood. The account may be thought longer than
was necefTary ; but I was willing to be as full and
particular as poffible, as I confider’d it as a kind of
appeal to my teftimony, and as the ob^edt of it re-
fpedted the improvement of thofe branches of fcience
fo interefling to mankind, the medical and anatomical.
I have put down only what I faw, without any re-
gard to what he has printed. As Father di Torre’s
more particular view in propofing to me to go through
thefe obfervations with him, was the fatisfying of the
Royal Society of the fidelity and exadtnefs of the ac-
count he has given of this fubjedl in the book he
lately prefented to them, I muft defire the favor of
you to lay my account likewife before them ; and you
will alfo pleafe to deliver to them his paper of in-
ftriidlions for the ufe of the glah'es he has fent them.
J am, with great truth, SIR,

Your mofl obedient fervant,

To Daniel Wray, Efq;

F. H. Eyles Stiles.

K k

VoL. LV.

Defcripiio

[ 250 3

Defcriptio Novi Microfcopii, a R. P. Di Torre

conJiruSli,

A yricrofcopium quo utor idem eft ac iilud Wilfoni,
TVl. dmplex, aptatum fpeculo cavo ab artificibus
Londinenfibus, quod defcribitur ab Henrico Baker in
Microfcopio ad captum vulgi cap. iv 5 quoniam tamen
plura conducere poftunt ad microfcopii perfedtionem,
illius quo utor tradam dimenfiones.

Capfulas rotundas, quibus, ope binorum cuculio-
num ex orichalco, claudo minimos globos, jam ad vos
mid. In his obfervandum fedulo eft foramen refpi-
ciens oculum fpedlatoris, quod & valde exiguum, &
perpolitum efle debet, & foramen quod refpicit ob-
jedum, quod fere ejufdem diametri efle debet ac
globulus j ita ut hie fere a foramine elabatur. Cap-
fulas accuratius conficient artifices Londinenfes, ut
globuli conflituantur in centro capfulas, & cuculiones,
non ope ceras, fed cochleas, firmentur.

Eft intra corpus microfcopii alia capfula rotunda,
diverfa ab ea qua utitur Wilfonus, cui imponuntur la-
minulae orichalceas cum quatuor, vel quinque forami-
nibus munitis duobus talcis pro objedlis. Capfula
hsc Integra eft, & intra ipfam filum orichalceum,
quod inftar elafterii firmas detinet laminulas cum
objedis. Supra hanc capfulam, eft intra corpus mi-
crofcopii alium filum orichalceum ut, cum luEC capfula,
ope tubi inferioris, cum cochlea furfum impel litur ut
objedum globo appropinquetur, non excurrat latera-
liter, fed 'in eadem maneat diredione.

Huic tubo cum cochlea, qui eft intra corpus micro-
fcopii, & quo objeda appropinquantur, globo adhas-

ret

[ 2SI ]

ret in parte inferlori tubus alius, qui ope cochleas aptatur,
cujus longitudo eft pollicis Parifienfis cum tertia
parte. Hoc utor ad excludendum lumen laterale
fuperfluum, 6c dirigendum lumen a fpeculo concavo
inferior! reflexum pro objedis illuminandis. Quando-
que, fi lumen a fpeculo reflexum fatis vividum fuerit,
intra hunc tubum apto fucceffive diverfa diaphragmata
lignea cum foraminibus i. vel JL pollicis Parifienfis ad
arcendum lumen fuperfluum, 6c ut ea tantum
portio luminis introducatur, quas neceffaria eft ad il-
luftrandum objedum, ut dare 6c diftinde videatur.
Ad eundem efedum parata etiam habeo plura dia-
phragmata ex charta craffa, quae fpeculo concavo
fuperimpono.

Sub microfcopio adeft duplex fpeculum concavum,
cujus centrum diftat a piano fubjedo per pollicem
Parifienfem cum dimidio, 6c ab objedo illuminando
per pollices quatuor. Focus fpeculi ex una parte eft
pollicum 2 cum dimidio, ex alia vero parte pollicum
2. Hoc ultimo fpeculo utor cum lumen eft nimis
vividum. Ut lumen probe a fpeculo refledatur, cu-
randum eft ut lumen fumatur ab aliquo pariete extra
cubiculum, qui a Sole illuminatus fit, 6c lumen in-
tra fpeculum ab alto cadere debet ; fi cadat fub angulo
fere 6o graduum, tunc lumen eft optimum. Quando-
que, fi nullus fit paries ante cubiculum, utor lumine
reflexo cceli ; fed tunc diaphragmata adhibenda funt,
donee objedum dare, diftinde, 6d vivide oculis af-
fulgeat. Quandoque, fi globuli praecipue minimi funt
aut Sol non luceat, nec diaphragmata adhibeo, nec
tubum inferiorem microfeopii.

Totum artificium pro ulu redo hujus microfeopii
cum globulis in eo conftituitur, ut lumen_ aptum ad-

K k 2 " hibeatur

oculis nudis diftinguuntur, & adeo exigute fuperfrciei
ut radii luminis, licet exiliffimi, fenfibilem habeant ad
ipfani fuperficiem ratlonem, quod in lentibus, aut
globis majoribus non evenit. Ideoque has omnes
cautiones quas adhibendae funt plufquam par erat
forfan expofui ; ufus enim quae neceffariae tantum
funt facile edocebit.

HE firfl obfervatlon was made July a'’, 1761,

with Wilfon’s frngle microfcope, conftrudted
for a perpendicular infpe6lion, with a mirror beneath
it for rededlng the light. The inftrument was placed
on a table near to a South window, but the fun’s
rays were not refledled on the objedt j it being Father di
Torre’s opinion, that the ordinary day-light would
Ihew the globules in a more natural ftate. A fmafl
drop of blood was included between two talks, and
was changed during the obfervatlon, in order to give
the appearance all the advantage that might arife
from the accidental htuatlon of the globules between
the talks, and alfo to renew their motion; for al-
though the blood viewed in this manner is not in a

O ^

ftate of circulation, yet, either from the vacuum
formed between the talks, the attradion of their
furfaces, or fome other caufe, the ferum is feldom in
a quiet flate on its being firft included between them,
and the globules that float in it move for fome time

An Account of fome microfcopic Obferuations on the

human Blood.

m

[ 253 ]

in various direcftions as the current of the ferum in»*
dines them, or as they themfelves are more or lefs
attracted by each other or by, the talks, till the whole
has found a Ifate of reft.

The magnifier applied was a fpherical glafs, which
he computed to magnify the objedt 512 times in
diameter.

In thefe views, the globules, though they varied
a little from each other in their outlines and dimen-
fions, appeared in general to be circular or elliptic,
and of the fize of fwan-fhot. Their figure as folids
was not eafily to be determined in fuch an expofition
of them, but they had the appearance of oblate
fphaeroids much comprefted, although, from their
free motion with the ferum, it was manifeft they
fuftered no preftlire from the talks ; where the focus
was perfedt, or nearly fo, the middle part of each
globule was darker than the margin j and this differ-
ence in fhade gave them an appearance, as if a dent
or concave impreflion had been made on their fur-
faces, which refembled thofe of young peas that
have dimpled in the boiling. What this darknefs
next the center was owing to, will appear from the
fecond obfervation j but in this I could not judge it
to arife from any thing but a finldng in of the furface
in that part, or fome accident of the light that fur-
nilhed fuch an appearance.

July 9’^, a fecond obfervation was made with the
fame inftrument, to which was applied a fphere
which magnified the objedt 1280- times in diameter.
In this view,, the variation of fhade on the middle
part of each globule from that "of the margin, was
fuch as carried with it ftrongly the appearance of a

perforation.

[ 254 ]

perforation. I had Indeed my doubts of this on firfl:
examining them, becaufe, on a very flight alteration
of the delicate focus of fo high a magnifier, the light
and dark parts would interchange, fo that the re-
fradtion or refledtion of the light might flill be
fufpedted to occafion the appearance in quefiion : but
continuing my view ftedfaftly, and taking notice of
all the diverfities which a numerous colledlion of
globules prefented, I remained at lafl thoroughly con-
vinced that they were perforated j for, when any of
the globules happened to move with the ferum in
the moft perfedt focus, which could not happen to
all, in a medium of fome little depth, I could with
great clearnefs diftinguifii the exterior and interior
circumference of the ring, of which each globule
confifted ; the interior one being bounded by a black
line or fhade next the perforation, exadlly refembling
that which bounded the exterior one, and diftin-
guiflaed it from the ferum without. In fuch globules
I could alfo eafily obferve the ring to be articulated,
the tranfverfe lines at the joints being very difiinguifh-
able. The figures of the articulations were various ;
in fome they were roundifli, fo that the ring ap-
peared like a bead necklace; in others, cylindrical,
and of fome length. The number of which the whole
was compofed, fe.emed uncertain, varying from two
or three to fix or feven ; many of the rings were
broke, either by fome confinement of the talks, or
by beating againfi; each other, which I faw them
continually doing ; and by thefe accidents the joints
of the rings were detached, and wandered about fe-
parately in great numbers ; and indeed they appeared
ieparable with as much eafe as if they had been united

C 25s ]

by mere contadl only. Some of the rings were
broke into femi-circles, others into greater or lefs
portions, and others again divided into their confti-
tuent articulations, which in fome places floated
about fingle, and in others formed by their mutual
attradion a lateral union, like the pipes of an organ.

I muft obferve alfo, that thefe feparated parts feemed
to be hollow and tranfparent, and, like inflated bladders,
would eafily yield, and change their figure, ftretching
or contrading themfelves from round to oval and
cylindrical, and 'vice verja^ as any lateral preflTure in
crouding along with the ferum brought a conftraint
upon them. As they floated at different levels, I
obferved many of them pafs over or under each
other without interruption, and the fame would hap-
pen alfo to the whole rings and larger portions. I
remained, therefore, after repeated examinations of
the globules in this ffate, without the lead doubt
either of their perforation or articulation; for al-
though the articulation was not diflinguifliable in
every globule, I think it was fo in the greater part
of them ; and it is natural to imagine that the reft
were articulated likewife, though they might not.
pafs at the proper diftance for its being diftinguifhed.
I omitted to fpeak of the fize of the globules in this
obfervation, nor indeed can I, from fo various an ap-
pearance, form any judgment thereof, farther than to.
lay that they appeared in general much augmented
beyond their appearance on the 2d of July.

Auguft 27^^, a third obfervation was made with
the fame inftrument of fome blood dropped upon a
fingle talk, and view’d as it lay without any cover,
fo that there could be no comprefiion. I view’d it,

whilil

[256]

whllft the globules were ftill in motion, with a
fphaerule that magnified the diameter 1920 times ;
and in this view the globules appear’d fo clearly to
be hollow rings, that there was not room for the
lead fufpicion of the reality of the fadt from any
circumftance. The diameter of the perforation ap-
peared much larger in proportion to the thicknefs of
the circumference than it had done in the former
views. The figure of the rings, where they were
free, and in their natural date, was circular ; but
where they were fo crouded together as to comprefs
one another in their pafi'age, they afilimed a variety
ot diderent figures, although they generally redored
themfelves to a circular figure again, unlefs broken
by the comprefiion which frequently happened, and
then the broken parts floated fcparately; or, if they
opened at a fingle joint only, the whole of the ring
would float along, varying its figure occalionally
from that of a portion of a circle, which it would
fird aflume, to a draight line, an undulated one, or
fome other accidental incurvature. The articulation
was vifible in feveral of the perfedt rings, but for
the mod part it was not to be didinguilhed, tho’
even in thefe, from their breaking fo eafily, it was
not to be doubted but that they confided of the
lame detached members or joints as thofe in which
the tranfverfe divifions were vifible.

Upon applying afterwards magnifiers of lefs power
to the fame blood, the greater advantage of light
made the rings appear dill more perfedt and didind^j
but as thefe were not applied till the globules had
lod their motion, and the whole drop had grown
dry upon the talk, tlie divifions at the joints were

I

none

C 257 ]

none of them vlfible ; almoft all the globules or rings,
as I mufl: now call them, had, upon drying, formed
themfelves into perfect circles. The moft complete
and fatisfadory view I had of them in this dried
ftate, was with a magnifier that encreafed the dia-
meter 640 times j tho’ the perforation was diftin-
guifhable even with one which encreafed it only 129
times. In many places the globules had, by the
drying of the whole drop, united into a clofer body,
and feem’d as if cemented together by a grumous
fubftance of a blackilh or deep red colour, which
pofiefied and filled up all the exterior fpaces form’d
by the union of fo many circular bodies j but the '
interior fpaces or perforations of the rings were ftill
free, and for the moft part diftindly vifible, fome
few places excepted, where the globules feem’d to
have united over one another, and not only lay in
too much confufion to give room for any proper ob-
fervation of them, but formed alfo a body too denfe
to tranfmit the light. The grumous fubftance above-
mention’d, as it extended itfelf along the exerior
fpaces, had the appearance of a ramification ; and it
was perhaps in fome fuch ftate that the globules were
view’d by Dr. Adams, whofe glaftes induced him to
fufpe(5t the truth of the common opinion, that -the
blood confifted of globular particles, and to deferibe
them rather as imitating the branches of a tree. See
his Remark on Blood, in Jones’s Abridgment of the
Philofophical Tranfadions, vol. IV. p. 204.

L I

VoL. LV.

A Letter

[ 2S8 ]

J. Letter of Sir F. H. E. Styles, F. R. S. to Daniel
. Wray, Efquire, F, R. S. on the Sexes of Plants,

• Naples^, December 29, 1761.

S I R,

ReadDec. I2,y Enclofe you Profeflbr Cyrillo’s draw-
A ings of the objedls lately viewed with
the microfcopes of Padre di Torre, which he de-
iires may be prefented with his refpeds to the Royal
Society. The explanation I have annexed of the
figures, will in fome meafure fliew how they lerve
^to confirm the remarks I fent you on the impregnation
of vegetables. However, that our reflexions on this
fubjeX may receive a more methodical fupport from
them, I enclofe you another copy of the remarks,
with numeral references to thofe figures, that ferve
to verify the account given of the particular appear-
ances, which 1 was obliged to omit in the firfl; copy,
as the figures had not been then ranged and num-
bered.

In my letter of the i6th of November, accom-
panying thefe remarks, fpeaking of the clafs Dicecia,
I faid, that there mufi: in this clafs be fome original
difference, either between the corpufcles which pro-
duce the male plants, and thofe which produce the
female ones, or between the refpeXive ova which re-
ceive them : a further refleXion fince upon the fubjeX
has led me to doubt whether there is a necefiity for
fuch fuppofition, there occurring to me another way

of

[ 259 ]

of accounting for this part of the oeconomy of Na-
ture, which I not only think a more probable one,
but which, if all the circumftances to be explained
are duly attended to, will, perhaps, be thought to
amount to more than a conjedture. I would fuppofe
that not only in the Dioecious plants, but in the
Monoecious and Polygamious alfo, and, to fpeak
more generally, in all cafes where the male and fe-
male organs are found feparate, the defedt is not
in the flower, which I fuppofe to be originally in-
ftrudted with the rudiments of the organs of both
fexes, but that it arifes from fome circumftance in the
plant that deterniines it to blow the one organ and not
the other.

That the abfence of the rudiments is not to be
inferred from the want of their expanfion appears
plainly from the following circumftances that fall
under every one’s obfervation, viz.

That plants do not produce their flowers all the
year, but only at particular feafons. ,

That many plants are fome years before they pro-
duce their flowers, and hardly any, except annuals,
blow the firlt year after they are fown.-

That foil, climate, pruning, and many other cir-
cumftances, will bring plants to blow fooner or later
than they would otherwife do.

That culture will encreafe the quantity of bloom,
and thereby occafion the expanfion of flowers, which
would otherwife have remained within the wood.

Now if thefe circumftances, which are fimilar to
thofe of which the explanation is fought, be fo com-
mon, I afk why we may not in like manner fuppofe,
“ that, whenever either the male or female organs

L 1 2 “ arc

[ 26o ]

“ are abfent, it is owing to fome circumflance that
determines the fap into other channels, and thereby
“ prevents the expanfion of the part.”

I faid this would, perhaps, be thought to amount
to more than a conjedture ; becaufe, befides its proba-
bility from the circumftances I have ftated above, it
will perfedly explain another well attefted phaeno-
menon in the clafs Dioecia, that is fcarce to be ac-
counted for on any other fuppofition. viz. that a male
plant has, at a certain age, been found to change to
a female one, and v/ce verfa^ and alfo to bear flowers
of both fexes, to which I may add another which
I have myfelf obferved in the Monoecious plants,
Zea and Ricinus, where I have often found fpikes
of fruit breaking out amongft the male flowers, though
they commonly come out feparate from them in
another part, of the plant.

If there be any weight in the arguments I have
here ufed in fupport of this fuppofition, the general
conclufion will be this, that the flowers of all vege-
tables whatfoever are hermaphrodite in their origi-
nal conilrudion, though both the organs do not ap-
pear in all cafes.

I am,

S I R.

Your moft obedient Servant,

F. H. Eyles Stiles.

Remarks

[ 2^1 ]

Remarks on the Impregnation of Vegetables.

IpP A C H grain of pollen is a velTel filled with pul-
py matter, in which are lodged a confiderablc
number of fmaller grains, which may be called the
impregnating corpufclcs (Figure 2, 3, 4, 5, 6, 7, 8,
9, 10, II, 12, 13). Thefe are not vifible with the
naked eye, but may be diftinguifhed with glafies of
moderate power, if the grain be tranfparent, or if
the pulp be forced out by compreffing the grain be-
tween the talks. They are round, tranfparent, and
nearly of the fame fize in all plants. They are con-
veyed to the germen through the %le, which is
furnifhed with internal duds for that purpofe j and
in the clafs Syngenefia, and in the fmall plants of
other clalTes, where the flyle is {lender and tranfpa-
rent, they may be difHnguiflied in their paflage
(Figure 19). The manner of their reception into the
iifyle depends on the difpofition of its furface : our
obfervation fell chiefly on thofe plants that have hairy
ftyles or ftigmas ; and in thefe the corpufcles enter by
means of the hairs, which are often found on the
ftyle itfelf, fo that the ftigma mufl: not always be
looked upon as the only recipient part, though it
may, perhaps, be fo in mofl; indances. The hairs
are fo many tubes open at the extremity for the
reception of the corpufcles j they are ufually fhaped
like a thorn, or prickle, widening towards the bafe.
They are each of them furnilhed with a canal, or
tube, which divides itfelf at the broader part of the
hair, and enters the piftillum in two branches (Fi-
gure 17) which run on till they join the longitu-
dinal

[ 262 j

dinal duds that lead to the germen (Figure 21).
Thefe canals, after tiiey enter the piftillam, a% lefs re-
gular, branching out frequently into fmaller ones,
which, indead of running directly to the longitu-
nal duds, vary their direction, and fall into the ca-
nals that run from the hairs next adjoining, fur-
niOiing the appearance of an irregular reticulation
(Figure 22), though neverthelefs there are com-
monly principal canals obfervable that run more di-
redly towards the longitudinal dud:s, and fall into
them (Figure 22). The corpufcles are admitted
into the hairs in the following manner ; the grains
of the pollen having difperfed themfelves about the
ftyle and ftigma, great numbers of them find a
lodgement amongft the hairs ; thofe which fall be-
tween the hairs, or cling to the Tides of them, may
be fuppofed to lofe their effed:, which will not be
thought improbable, if it be confidered what an
abundant provilion there is of the pollen, and how
large a part of it mud neceflarily be waded by be-
ing carried away by the flower, or at leafl not fall-
ing on the female organs, but there are many of the
grains that fall on the points of the hairs (Figure
23), and thefe furnifli the impregnation. The
grains being arrived at a ftate of maturity before they
iflued from the antheras, are prepared to burd and
difcharge their contents when they fall on the hairs,
and the female organ aflids likewife in producing
this effed: ; for foon after a grain has lodged itfelf,
the point of the hair begins to open, and the mouth
extends itfelf by degrees over the furface of the
grain, till almod: the whole body of the grain is
drawn within the tube (Figure 23) j indhis fituation.

. [ 263 3

the grain foon yields to the compreffion of the tube,
and difcharges its corpiifcles, which, with the affift-
ance of the fluid parts of the pulp that enter with
them, or of the juices with which the tube itfelf is
furmflied, float on till they enter the longitudinal
duds, which convey them to the gerrnen. The
grains, after thus emptying themfelves of their con-
tents, withei and contrad, and, falling off from the
mouth of the tube, remain in a periflied ftate about
the Tides of the piftillum (Figure 19). The figure
of the hair, whilfl; the grain is lodged in the mouth
of the tube, is remarkable ; for the tube is then
widefl: at the extremity, and leffens gradually as far
as the bifurcation, where it forms a narrow neck,
which gives a bell-fliaped figure to the fuperior parts,
whilft the lower part widens again towards the bafe
(Figure 23). In tranfparent %les, the duds that
lead to the gerrnen maybe feen filled with corpufcles,
which, being fupplied in great quantities from the
hairs, pafs on through thefe duds in regular lines fo
clofe as to touch one another (Figure 19). In fom'e
infpedions, the corpufcles were feen to move both
in the hairs and in the principal duds of the ftyle,
which fhewed them to be detached fubfliances, that
could pafs freely with the current of the juices in
which they floated ; but their regular progrefs to-
wards the gerrnen was dcubtlefs interrupted by the
gathering of the flower, fo that the motion obferved
could only be afcribed to accidental attradions, which
put the juices in motion between the talks 3 and this
was evident alfo from the diredion of their motion,
which was cafual, and not always leading towards
the gerrnen. The number of the principal duds

that

[ 264 ]

that lead to the germen cannot be afcertalned ; they
probably vary according to the number of loculaments
to be fupplied ; more than one was commonly ob-
fervable with the corpufcles paffing in clofe hies
through them, as has already been defcribed. In
the piftillaof flowers in bud, no corpufcles could be
difcovered j which is a hrong proof that they are re-
ceived from the pollen, and deftined for the im-
pregnation.

Upon examining the pappus or down that crowns
the ieeds in the clafs Syngenefia, the hairs of the
pappus were found to be hollow, and filled with the
lame corpufcles (Figure 24). How the corpufcles
are admitted into them, or for what purpole they
are lodged there, muft be left to further enquiry ;
in the mean time, it may be obferved, that the fitu-
ation of the pappus makes it improbable that the
corpufcles fhould be received therein for the purpofe
of conveying them to the germen j and that there-
fore it is more natural to fuppofe, that the corpufcles
arrive there after their palTage thro’ the germen, and
that the hairs of the pappus ferve as excretory velTels
for taking off thofe that were ufclefs to the impreg-
nation. This is the more probable, as the great
quantity of them brought by the dudts mull; doubt-
lefs occafion fuch a fuperfluity.

Upon examining various plants of the order Filices,
of the clafs Cryptogamia, no male organs could be
difcovered. If the flowers of thefe plants be herma-
phroditic, the ftaminiferous part doubtlefs falls off as
icon as the impregnation is over, as it does in other
cafes ; fo that if the male organs are not fought for
at the precife time when the plant is in bloom, the

fearch

5

[ 2^5 ]

fearch muft_ be a vain one. The fruaification in
theie plants is for the moft part covered with a thin
membrane, which Mr. Miles calls a fort of fungus
or tubercle (Phil. Tranf. N“. 461.) and whichfat
Its hrft appearance, and for home time afterwards,
leerns to have its margin clofely adhering to the leaf.

th it is probable

that the floors do not blow till the margin has de-
tached itfelf from the leaf, and admits the air to
come under it, for the maturation and difperfion of
the pollen. This may, perhaps, point out the cri-
tical time for fearching for the anthers. However
this may be, the antherse and pollen are probablv
very minute; and as it is no eafy talk to niake the
examination of what is concealed under thefe mem-
branes with a fingle microfcope, to which the glafles
we have uled are commonly applied, we have not
yet^tound the means of difcovering them. The feed
veflels and feeds have been already well defcribed
and figured by Mr. Miles; however, as fome deli-
neations were made of them as they appeared to us,
they will accompany the other drawings (Figures 2 c
26, 27, 28, 29, 30, 31, 32, 33, 34, 3^, 36 ) and
may ferve to confirm Mr. Miles’s account of them.

in the male flowers of Marchantia Polymorpha
^inn. the grains of pollen were obferved in a thick
tuft of hairs, where they feemed rather to have lodged
thenifelves accidentally after their difperfion, than to
e aftxed to them as they are defcribed by Linnsus
(Farma crinulo affixa. Gen. Plant.) Thefe hairs,
viewed with the microfcope, had a remarkable ap-
pearance each hair confifting of a double chain,
and each chain being compofed of round bodies
Vou LV. M m placed

[ 266 ]

placed at regular diftances from each other/ and
.connected by a thread. The two chains are fo clofe
to each other, that the bodies touch one another in
pairs, the whole making . a regular figure. After
comprefling one of thefe hairs between the talks,
the two chains feemed to have twifted round each
other, and to exhibit an appearance fomewhat re-
fembling the cable of a fliip. Of the ufe of thefe
hairs in the male flowers, we could form no con-
jedtures. The figures of them will be found amongfl:
the drawing (Figures 37, 38.)

Explanation of the Figures in Tab. VIII. and

Tab. IX.

' N. B. The generic and fpecific names here ufed
are the Linnaean.The numbers in the column
on the right hand fhew how many times the
objedf was magnified in diameter.

#

Fig. I. A grain of the pollen of Hibifcus

Syriacus, 5^2

2. Thefame, with the impregnating cor-
pufcles forced out by comprefling
the talks, 512

* 3. Some of the fame corpufcles feparate

from the grain, and more extend-
ed in length, which was fuppofed
to arife from their adhefion to ono
. - another, tho’ the divifion was not

perceptible, ' 5^^

3

4. Grains

< '

» ^ »

_ -

■ ' *

i

\

.’- .vr

■ V ^

'..4

[•267 ]

Fig."4‘ Grains of the pollen ofMirabilis jalapa
with the impregnating corpufcles
feen within them, 72

5. A grain of the fame, 512

6. Three grains of the fame flicking to-

gether, 1280

7. Corpufcles of the fame, viewed fe-

parate, 1280

8. A grain of the pollen of Cucumisfa-

tivus, with the corpufcles within
it, and fome on the outfide, that
had been forced out, 192

9. Grains of the pollen of Bignonia ra-

dicans, with the corpufcles within
them,

10. A grain of the fame, 1280

11. Corpufcles of the fame, view’d fe-

parate, 1280

1 2. A grain of the pollen of Gomphrsena

globofa, comprefled, 1280

13. Grains of the pollen of Bryum, with

the corpufcles within them, 1280

N. B. The fame corpufcles were feen in the pollen
of Atropa, Hyofeyamus, Scilla, Scabiofa, Vale-
riana, Verbafeum, and a great number of other
genera j but the delineations were omitted,
as. the appearances were nearly, alike in. all.

Fig. 14. The flyle and fligma of Leontodon

taraxacum, 72

15. Two hairs of the fame, in which the

perforation was diflinguiihable, 1280

Mm2 Fig.

72

[ 268 3

Fig. 1 6. The ftigma and part of the %Ie of
Carduus crifpus,

17. Two of the longer hairs of the fame,

in which the canals or tubes, with
their bifurcation, are fhewn, and
the corpufcles pafling thro’ them,

18. The ftigma and part of the dylc of

Conyza fquamofa,

1 9. A portion of the ftyle of the fame,

with the corpufcles paffing thro’
its longitudinal duds, and the
emptied grains of the pollen ad-
hering to its lides, after having
dropped from the hairs of the
ftigma.

20; A perfed grain of the pollen of the
fame,

2 1 . Part of the fide of a flyle of Solanum

oflicinarum, with its hairs, and
the continuation of their canals
thro’ the body of the flyle,

22. Part of the fame, in which the

tranfverfe communication be-
tween the canals is fhewn,

23. A hair of the fame, with a grain of

pollen lodged within the extre-
mity of the tube,

24. Part of a hair of the pappus that

adheres to the rudiments of the
feeds in Sonchus oleraccus, with
the corpufcles within them,

1280

72

859

859

128

38+

1280

1280

Fig. 25.

[ 269 3

Fig. 25* A leaf of Afpleniurn ruta murarla,
with its feed veffels, which in
this plant have no membrane that
covers them.

26. The feed veflels of the fame, with
their elaftic rings,

^7* A feed vellel of the fame, broke by
compreffion, with the feeds fall-
ing out,

28. Seeds of the fame,

29. A feed veffel of the fame, in which

the parallel ftreaks on its exterior
furface are fhewn,

30. A fmall portion of the capfular part

of the feed velTels of the fame,
on the furface of which there ap-
peared fmaller ftreaks, which fub-
divided the parallel ones fhewn
in Fig. 31.

3 !• A portion of the ring of a feed vef-
fel of the fame,

32. A fmaller portion of the fame ring,
in which was obferved a plane
fide at the under part, where it
adhered to the capfule^ upon
examining the broken part at the
end, the ring appeared to be
folid.

42

128

859

128

859

512

Fig, 33.

[ 270 ]

Fig. 33* ^ membrane that covered the fruc-
tification of Polypodium filix was
feparated from the leaf, and
fhewn as it appeared upon view-
ing its under fide with fome of
the feed veflels adhering to it.
(a) The broken part where it
had been joined to the leaf.

34. Some of the feed veflels of the fame

viewed feparate,

35. The peduncle of a feed vefiel of the

fame fupporting the ring,

36. Part of a leaf of Adiantum capillus

veneris, fhewing the membrane
> which grows from its margin,

and which folds over it to cover
the friidlification, but had been
unfolded for obferving the under
fide and feed veflTels, which are
here fliewn.

37. Part of one of the hairs of the male

flowers of Marchantia polymor-
pha, with fome of the pollen,

38. The fame compreflTed,

48

1280

1280

1280

i

XXIX. An

[ 3

XXIX. An Account of the Sequel of the
Cafe of Anne James, who had taken the
Green Hemlock : In a Getter to the Rev*
Thomas Birch, Secretary to the Royal
Society^ fro?n Mr, Jofiah Colebrooke,
F, R, S.

Rev. Sir,

Read Nov. 7, A S I did myfelf the honour, in De-
*765- cember, 1763*, to communicate

to the Royal Society, the good fuccefs which had
attended taking green hemlock, in the cancerous
cafe of Ann James (who had at that time taken it
for more than a year), I think myfelf under an in-
dilpenfable obligation to give the fequel of that hifto-
ry, by which it will appear, that the taking hemlock ,
(tho’ attended with fuch advantageous circumftances,
and which continued for near two years) proved only
palliative.

In July, 1764, I was informed, that the fchirrus
in the right brealf (which was very fmall when fhc
began to take hemlock) was encreafed, and extended
itfelf under the axilla, looked livid, oofed a little,
and was painful. I defred a little blood might be

* See Philofoph. Tranfa£l. vol. LIII. p. 34^*

taken

4

[ 272 ]

taken away, that flie might take rhubarb or magne-
fia to go through her, and then purfue the fame
regimen with the hemlock, (he had followed before.

For external application, I delired an ounce of
common lead might be fcraped as thin as pofliblc, and
infufed in two ounces of fallad oil, to be fhaken daily
for two or three days ; when fettled, to moiften a
linen rag with the oil, and apply it to the part j to
renew the dreffing every day, and to fliake the bottle
every time after they had ufed it, that the oil might
be the better impregnated with the drying quality
of the lead.

That, if the pain encreafed, they might ufe the
following cataplafm, viz. Green hemlock one ounce,
boiled in a fmall quantity of milk till tender, and
then thickened with linfeed meal, or oatmeal, and
a little oil, and applied barely warm (over the other
drefiing) once or twice in a day.

In September, 1764, I faw her ; fhe complained
that her pain was rather encreafed j and upon exa-
mining her breafts, found the left (of which (he
firfl complained) quite eafy : in the right breaft the
nipple was drawn in, and the fchirrus of a purple
colour, but the difeharge was very fmall. I advifed
her to perfift in taking the hemlock, and purfuing
the former regimen.

In May, 1765, I was informed that her pains
were fo much encreafed, that fhe was obliged to
have recourfe to opiates : her breaft difeharged a
great quantity of foetid matter, as is ufual in cancers 3
and fhe ended a miferable life in September laft.

5

I hope.

I hope, your wonted goodnefs wiirexcufe mv
troublmg you to communicate this paper to the So-
ciety j and that you will, believe me to be with
great refpedt and efteem, *

Rev. Sir,

Budge Row,
Oil. 31, 1765.

Your mojft humble fervant,

Jof. Colebrooke.

Received November 30, 1765.

XXX. Some Account of the EffeBs of a
Storm of Thunder and Lightening in
Pembroke Collegey Oxford, on June 3,
176^ : In a Letter from Mr. Griffith,^
of the faid Collegey to the Rev. Tohn
Swinton, B. D. F. R. S.

Rev. Sir, ■ .

ReadDcc;,o, TN compliance with your requeft, 1

JL. fend you an account of the ftorm of
thunder and lightening, which fell upon Pembroke
college, on Monday, June 3" laft. You intimated
to me, that fome gentlemen of your learned Society
had exprelTed a defire of feeing an authentic account
of it ; and you have my free leave to communicate
tins to them, if you think proper,

VOL. LV. ]V

In

[ 274 ]

In the afternoon of June a very black clpud
appeared in the vwnd, which was, I believe, nearly
M.' E. A little before four, a gentle rain, attended
with flight thunder, fell, juft* fuftrcrcnt to wet the
furface of the ftreets, &c. But the wind blowing
from the northward, the wall of the college fronting
the fouth. remained perfectly, dry^ About half hour
paft four, came a terrible flafti of lightening, at-
tended at the fame inftant by a violent clap.of thun-
der. 'The lightening was of a remarkably ‘red co-
lour, and at the inftant of the flafh, every body, for
a conliderable diftance round the fpot where the
damage was done, felt and complained of an intenfe
heat j feveral people were cither forcibly beaten
down, or fell through fear and furprize. Some have
told me, they thought themfelves in the middle of
fire.

Whether the rain- had in fome degree difperfed
the eledlrical matter, which was colleded again by
the attradion of the metal in the windowsj whether
it came in different ftreams, or one great one which
divided itfelf, I fhall not pretend to fay j but it en-
tered into the fouth fide of Pembroke college in four
different places at the fame inftant. I fhall give you
an exad account of the effeds of it in each room,
A chimney which fronted the S. was beaten down,
and looked exadly as if it had been cut off in the
fhaft, about 1 2 feet from the top. In the garret to
which the chimney belonged, there is a lath and
plaifter wall running on each fide the fire-place, for the
convenience of the room, fupporting a kind of dormer
roof. At the end of this wall, was a ftrong oak poft,
which I obferved afterwards was full of nails. This

poft.

C 275 ]

port, roof, &c. was thrown into the room, to a
fiderable diftance, and {battered to pieces ; and the
window fronting the quadrangle to the N. was
blown outwards. It was at firfi apprehended, that
this was the only part of the college which was
ftruck, and that the mifehief done in the other
rooms was only the effeds of the fame ball (if I
may call it fo) conduded from this garret to the
other parts. But I confefs myfelf very doubtful of
this : for, had that been the cafe, it (hoold feem that
the diredion of the cledrical matter mud have been
altered, whereas in every room its courfe was from
S. W. to N. E. The garret above-mentioned was
uninhabited. The room underneath in the middle
dory belongs to the Rev. John Collins, M. A. and
F ellow of the college, who, mod providentially, was
out of town. The lightening entered his room at
a window on the W. fide of the fire-place ; the cafe-
ment (an iron one) was open, and was little or not
at all damaged. The window-curtain, with the
'frame it hung upon, was thrown at lead 20 feet to
the oppofite corner of the room j the window-feat,
and all the wainfeoat about it, were fhattered to pieces,
and carried away in the fame diredion with the cur-
tain. The door of the bed-chamber, near the win-
dow, was extremely fcorched, and at the didance of
a few feet, was a beaufet which was likewife much
fcorched, and the brafs efcutcheons were all forced
off. There was in this beaufet fbme valuable china,
and a quantity of glafles, which fullered much. Some
of the china had Mr, Collins’s arms fixed upon it,
and was gilt round the edges j two cups of this kind
had each two little triangular notches cut in their

N n 2 rims.

[ 2?6 ]

the giithng in thofe parts being defed:ive. . A
number of china plates, glaflcs, &c. were broken.
On the loweft (helf was a quart drinking-glafs, which
had long ftood there, inverted. It was probably in
fome degree faftened to the Ihelf by the paint. This
glafs was alrhoft reduced to duft, a great deal of
which was found on the uppermoft fhelf of all. This
was, I prefume, owing to the fudden expanfion- of
the air within i and to the fame caufe it muft be at-,
tributed, that the tops of the canifters were taken
off.^ The tea-fpoons were found difcoloured and
black j but Mr. Collins recolleded, that a fmall drop
of mercury from a broken barometer was left in the
beaufet, which no doubt difcoloured the filver. The
window fronting the quadrangle to the N. had every
pane of glafs in it forced^ outwards, and broke to
pieces; the cafement, which was open,, efcaped un-
hurt. The lead belonging to each pane was bent
outwards exactly in the middle, but there were no
figns of fire here ; and indeed it is probable, that
the lightening reached no farther than the beau-
fet. The window was undoubtedly blown outwards
by the fudden expanfion of the air, from the intenfe
heat on the other fide of the room. A young gentle-
man, who flood in his window, was almolt blown
down by this fudden guff of wind. It muft not be
forgotten, that a painter was at work in this room
when the accident happened. He was providentially
at the window, on the other fide of the fire-place
trom that w^hich the lightening came in at. His
.account is, that he felt an intenfe heat; faw, as he
thought, fire running all round him in circles; that
he had a ftroke on the fhoulder, w'hich beat him

down.

C 277 ]

down, and made him lenfelefs for fome time; when
he recovered, the room was full of fmoke, and fmelt
flrongly of brimftone. Near the window, where
the lightening entered this room, it made a round
hole through the floor into the ground-room, inha-
bited by Mr. Williams, a young gentleman of this
college, who had gone out but a very little time be-
fore.. Whether the force which defcended from the
upper room might contribute to the damage done in^
this, cannot be well afcertained ; it is, however, ap-
parent, that the ele€lrical matter entered this room
from without, jufl: in the fame manner, and in the
fame dire<Siion, as in Mr. Collins’s chamber. Near,
one corner of the iron window-frame, a round hole,
about an inch in diameter, was flruck- through the
flone-work, as if made with a bullet. A ftrong iron
bar in the window was forced into the room, and
carried to fome diftance. The hinges of the window-
flautters, and ’the wall they touched, were difcoloured,
jufl; as if gun-powder had been fired upon them. A
nail happening to be in the ftone, on the fide of the
chimney, the lightening drove it with great force in-
to the folid freeflone, making a, round- hole toacon-
fiderable depth.- The window-curtain here was
thrown to the fame diftance,. and in the fame direc-
tion, as in the room above, and- pretty nearly the
lame efleds appeared j only the wainfcotand v/indow-
feat being, I think, made of a different kind of board,!
were not Ihivered into fmall pieces, as in the room
above, but were thrown in large fplinters, and with
great force, about the room ; Ibme of them broke
the window and a large looking-glals on ihe oppofite
iide, and more than one flew end- ways like an ar-
I row.

C 278 ]

row, with fuch force as to pierce through a very ftrong
lath andplafter wall, the ends of them appearing feveral
inches through the wall in the adjoining ftair-cafe.
Clofe to the window where the lightening entered,
was a ftrong piece of oak timber, being the corner of
the partition to a clofet. This poll, 9 feet long, and
6 by 64. inches in the clear, was thrown in a differ-
ent diredlion from any thing elfe, from E. to W.
into the clofet. It was carried near eight feet, and
then ftruck a cloaths prefs, with fuch force, as to do
it very confiderable damage. At the bottom of this,
a hole was made through the floor into the ground :
the window of this room was not blown out ; a
proof that the heat here was not fo intenfe as above.
Forfome time, it was fuppofed that thefe three rooms
only had fuffered ; but, going to view the ruins on
the outfide, I obferved fome traces of mifehief in
the roof of the garret oppofite to that firfl: mentioned,
and near 40 feet Wefi of the chimney which was
beaten down. 1 immediately went into this garret,
and though all had been over for more than an hour,
the ftench of fulphur remained fo ftrong as almoftto
endanger fuffocation. This garret had been for fome
time ufed as a lumber-room by the burfar, and,
within a few feet of the place where the lighten-
ing entered, lay a heap of old iron cafements^ it
came in here with an amazing force, and fhivered
the Fide-beam of the roof into ten thoufand little
fplinters, fcarcely larger than common needles. As
there were many boards, fhavings, &c. in the room,
it is more than probable fomething might have taken
fire, but moft fortunately under a large bow window

on

^ C 279 ]

on the South fide of the room were laid carelelly a
number of long iron window-bars almoft from one
end of the window, to the other. Thefe faved the
room from further damage ; the eledrical matter
was by- them conducted to the* corner of the window,
and there made a large round- hole, and went out of
the room to an iron cramp which is on’the outfide,
about Hi or 12 feet long, at the lower end of which
a ftone was cut by the lightening out of the wall,
and from thence it no doubt delccnded to the ftreet
(then quite wet) without farther damage. Upon the
whole, we think ourfelves extremely happy that no ^
more mifchief was done.

4

XXXI. On

[ 28o ]

Received December 5, 1765.

<

XXXI. On the Nature and Formation of
Sponges: In a Letter from John Ellis,
Efquirey F, R. S» to Dr. Solander,
F. R. S.

S I R,

Read Dec. ^9>'\T O U, who ftudy nature in an eml-
‘765- ^ degree, view her in all her

works proceeding by regular gradations from the
lowed; to the mod: perfeeft of all created beings among
thofe animals commonly called Zoophytes, you
may plainly dilcover an evident approximation, from
the ruded; irregularly-formed fponge (which is the
lowed being that 1 have yet obferved to have the
appearance of animal life) to the mod beautiful and
elegant red coral.

The nature and formation of fponges having ne-
ver yet been thoroughly invedigated, every attempt
to explain this dark part of nature mud give fatif-
fadlion to the curious. The intent, then, of this letter
is to convey to the Royal Society, through your
hands, what we have feen in the experiments we
made on them at the fea fide ; the fubdance of what
has been faid on the fubjedl by moderns as well as
ancients ; and ladly, to fliew how nearly they ap-
proach to the Alcyoniums, a clafs of beings next

above

[ 28i ]

above them in the fcale of nature, as being one ftep
nearer to the appearance of animals.

If we confult the ancients, we fliall find, that, in
the days of Ariftotle, the perfons, who made it their
bufinefs to colled; thefe fubftances, perceived a par-
ticular fenfation, like fiirinking, when they tore them
off the rocks j and, in the time of Pliny, the fame
opinion continued of their having a kind of feeling
or animal life in them ; but after his time no atten-
tion was paid to this kind of knowledge, and it ftill
remained a doubt, till the illuflrious Count Marfigli
pronounced them vegetable, as he did all the corals,
keratophytons, and alcyoniums, &c.

After him, it fell to the lot of the ingenious Dr.
Peyfonell, in his Enquiries, to difcover them to be
animals, or rather, as he calls it, the fabric of ani-
mals, formed by a fpecies of urtica marina (fee his
manufcript which he fent to the Royal Society in
the year 1752); but finding upon re-examining
thefe intricate bodies in fea water at Guadaloupe, he
favours the Royal Society with a letter dated from
thence, March i, 1757. Vid. Phil. Tranfadt. vok L.
p. 592. wherein he has given a particular account
of the animal, which he alfures us forms thefponges.
There is fomething fo remarkable in his defcriptioii
of the animal, and its manner of fabricating the
fponge, that I am obliged to quote the mofi; ftriking
parts, in order to fubmit the probability of it to you
and the reft of the Royal Society.

He takes notice, “ that the fame kind of animal
“ forms the four principal fpecies of fponges deferibed
“ by Father Plumier, as the tube Jponge, the cord-
“ like JpongCf the digitated fponge^ and the honey'-
“ comb fp072ge.

VoL. LV. O o

« Thefe

[ 202 ]

“ Thefe fponges,” he fays, confift of hard firm
** fibres, twifted about in doubles, and the interftices
filled with a mucilaginous gluey matter, having large
“ hollows, with cylindrical tubes, difperfed through
“ their fubflance/ forming a kind of labyrinth filled
“ with thefe worms.

He fays, he has obferved, “ that the fponges be-
gin to be formed on a nodule of petrified fand or
“ other like matter, round which the worms begin
to work, and round which they retire as to their
lafi; feat or refuge.

He then proceeds to ^ve a defeription of
them, which is, “ that they are 4- of a line thick,
“ two or three lines long, of a conic figure, with a
“ fmall black head furnifibed with two pincers j the
“ other extremity is fquare, and much larger than
the head ; their motion begins at the tail, and ends
** at the head j they are fo tranfparent, that the cir-
** culation of the blood may be perceived ; and
“ where the vifeera Ihould be, there is a kind of
circular motion of a blackifh matter moving to
“ and fro in the animal. He fays, he has kept
“ them alive more than an hour out of the f^nge,
“ and (which is very fingular) when he put them
“ near a piece of frelh fponge, where the nefts were
“ moift, and from which he had before pulled them,
“ he faw them enter and difappear. He goes on
** to tell us, that thefe worms have no particular
“ lodge ‘y that they walk indifferently into the tubu-
lar labyrinth ; fo that, he fays, without offence to
Pliny and other naturalifts, he does not fee that it
“ is in their power to dilate and contrad: the bodies
of fponges, which always remain in the fame fiate

“ of

[ 283 ]

“ of magnitude, without being fenfible to the touch,
” being an inanimate body j all the fenlitive life be-
“ longing to the worms.

“ He then tells us, that with the flaver or juice
“ they depofit, they make the fponge encreafe or
“ grow, as bees and watps, and elpecially the wood-
lice of America, encreafe their nefts and cells.”
This account appearing fo contrary to the proceed-
ing of nature in the formation of the other kindred
marine bodies, called Zoophytes, fuch as corals, ke-
ratophytons, and alcyoniums, particularly the laft ;
I was determined to find out the truth of this
extraordinary difcovery, which I found had been
thought worthy of a place in our Tranfadions.

Accordingly, in the year 1762, when we were
together at the fea fide at Brighthelmftone, we differed
carefully the fpongia medullam panis referens^ or crumb
of bread fponge, in hopes of difcovering the fmall ani-
mals that were fuppofed to fabricate them ; and were
fuprized to find a great number of fmall worms in
them, particularly a very fmall kind of nereis^ or
fea-fcolopendra : but thefe worms appeared evident-
ly, inftead of being the fabricators of it, to have
pierced their way into its foft fubftance, and made
it only their place of retreat and fecurity. After this,
we proceeded along the fea coafi: to Little Hampton,
near Arundel, on the coafi; of Suflex, where we took
up out of the fea feveral fpecimens of the fame fort
of fponge full of an orange-coloured gelatinous mat-
ter; and, while they were jufi: frefii from the fea,
we examined them (after they had refled for fome
time) in glalTes of fea water ; and to our great fur-
prize, inftead of feeing any of the polype-like fuckers,

O o 2 or

[ 284 ]

or any minute animal figure^come out of the papillae^
or fmall holes with which they are furrounded, we
only obferved thefe holes to contraa and dilate them>*
felves.- And as a further confirmation of this motion,
being at Haftings in Suffex, in Auguft 1764, in com-
pany with Dr. bowin Knight, F. R. S. we colleded
from the rocks at ebb-tide, juft under water, a va-
riety of the fame kind of fponge, but of a pale yel-
low colour, and in the form of feveral cocks combs
united together, the tops of which were full of tubu-
lar cavities or papillae : when we examined thefe m
glaffes of fea-water, we could plainly obferve, thefe
little tubes to receive and pafs the water to and fro j
fo that the fponge is an animal fui generis ^ whofe
mouths are fo many holes or ends of branched tubes
opening on its furface j with thefe it receives its nou-
rifhment, and by thefe it difcharges, like the polypes,
its excrements.

But, to give a further proof of fponges fuckmg in
and throwing out the fea-water, I fhall quote a pal-
{a<y& from that fair inveftigator of nature, the cele-
brated Count Marfigli, in his Hiftoire Phyfique de
la Mer, p. 53. who, notwithftanding he took them
for plants, as well as he did corals, &c. has in his
chapter on Sponges this curious obfervation,^ which

proves quite the contrary.

« J’ai un fond fuftifant de ces plantes pour en fairc
“ une botanique entiere, & plufieurs reflexions curi-
» eufes fur la fyftole & diaftole, que J’ai obfervees,
“ dans certains petits trous ronds de ces plantes, lors
“ qu’elles fortent de la mer, mouvement qui dure
“ jufqu’a ce que I’eau foit entierement conlumee.”

In Englifh thus : “ I have a fufficient flock of thelc
® “ plants

[ 28s ]

*'• plants (fponges) to‘ m^ke a compleat botanical
c6lle6tion, with many curi’oiis rertiarks, which I
have made on the fyftole and diaflole, which I
have obferved in certain fmall round holes, when
“ they are firft taken out of the fca j this motion
** continues in them till the water they contain is
entirely wafted away.’*

Nothing can more clearly defcribe what I have
feen in our fponges ; fo that, making an allowance
for the then prevailing opinion that they were vege-
tables, I think, he comes nearer the truth than Dr.
Peyfonell’s account of the formation^ of fponges by
little animals, that walk to and fro in the labyrinth
of the tubes to conftrua: his extraordinary animal

I come iiow to fliew you how near they approach .
to the alcyoniums in their internal form and manner

of growth. . ,

In order to explain this, I have given you the
perpendicular and horizontal fedtions of the cornmon
ofHcinal fponge ^ • becaufe this is in the power of moft
gentlemen to examine. And, iii vol. LUl. ot the
Philof. Tranf. Tab. 20. Fig. 10. c. A 1 1 and 13. 1 .
have given the perpendicular and horizontal lections
of the alcyonium mams marina^ both magnifkd
and in the natural fize ; becaufe fpecimens of this
kind are likcwife eafily obtained, being found in
plenty on rocks and fhells near the Ifte of Sheppey,
at the entrance of the river Thames. . , ,

You’ll obferve, the connected tubes of both anie
from the part to which they adhere to the rocks, &c.
From hence both kinds branch out and fwell into
irregular lobes, with this difference, that the furface

. * See Tab. X. fig. E and D.

[.286 ]

of the fponge is covered with holes guarded with
minute points like little fpines; the f^rface of the
alcyonium with ftarry openings of eight rays, from
whence the polype-hke fuckers are protruded, in or-
der to hnd out proper nourifhment : and thefe ftarry
openings m one, and the holes in the other, fo far
correfpond, that in both kinds they are found of dif-
terent hzes j but this is in proportion to the age of the
branching tubes that come to the furface.

fedions of the alcyonium you may plainly
diftinguilh the reticulated elaftic fibres, that enclofe
the tranfparent fiiff gelatinous part, as in the fponges:

1^*^’ ^ c j fnbftance is of a firmer texture

than what is found in fponges, it requires more pains
to feparate it from the elaftic fibres; however, with
a httle trouble it may be done fufficiently to evince
what I have endeavoured to prove, I mean, the great
proximity there is between the animal life of fponges

and alcyoniums, and confequently that both are
animals.

Before I conclude, I muft endeavour to remove
feme doubts, which feem to have diftrefled the Ge-
nerality of curious perfons to account for ; the one
IS, what occafions thofe very large holes that appear
here and there irregularly on the furface of moft
ponges the other is, how came thofe extraneous
bodies, fuch as fmall thells, ftones, and even parts
of fucufes, in the middle of thefe animal bodies ? In
anfwer tothe firft upon cutting open and examining
thefe bodies while recent in fea-water, as I havl
fliewn before, we frequently find a variety of
different .worms, who bore their way into them, and
make their nefts and retreats there, or perhaps to live

oa

2

[ 287 ]

on the gelatinous part of the fponge. This the ce-
lebrated Donati confirms, in* his Hiftory of the Adri-
atic Sea j who endeavouring to find out, like Peyfo-
nell, the animal fabricator of the alcyonium primum
Diofcoridis, which approaches very near to the
Iponges : he met with many irregular cavities in it,
and alfo different kinds of inhabitants ; one of them
he has particularly defcribed and figured. Vide
Donat. Hill. M. Adriat. p. 58. t. 8. fig. G. But he
very judicioufly fays, thefe are not the fabricators,
but the inhabitants ; and allows the alcyonium to be
of animal origin, in which he fays he has difcovered
evident marks of fenfation.

As to the fecond doubt, it may be obferved by the
curious enquirer into nature, that the fame property
of enclofing extraneous fubflances is common to the
whole clafs of Zoophytes, as they grow up, from the
fponge to the red coral. In order to prove this, I have
various fpecimens as well of fponges as keratophytons
and corals, with different bodies enclofed in them,
both animal and vegetable. I have fpecimens where
even the red coral enclofes the white coral, and the
white the red; with. many keratophytons, that have
enclofed fmall roundifli fhells of the barnacle tribe,
thought by fome fuperficial enquirers into nature
(who would have them to be vegetables) to be the
fruit of the keratophytons. Vid. Phil. Tranf. vol. L.
p. 853. Tab. 34. Fig. 19. I am,

SIR,

Your mofi obedient fervant,

John Ellis.

An

Giay’s-rni>,
Dec. 5, 1765.

[ 288 ]

An Explanation of the Plates.

Plate X.

A Is an Irregular pieccrof the crumb of bread. fponge,
found at. Pagham on the fea-coaft of Suflex ;
reprefent the papilltei through which the

- ; fponge receives and difcharges the water ; this,
when recent, is of. 'a fine orange colour.

Fig. B is the branched Englifh fponge j at bb^ along
the edges, and on the furface of the branches,
are rovvs of fmall papillary holes, through which

^ the animal receives -its hourilhment.

. ,

Fig.-C reprefents the downy branched Englifh Iponge
found on the Sufiex coaft ; this is covered over
with a fine down fo clofe, that it hides the
many fmall holes that are on its furface.

Fig. D; and E, the perpendicular and horizontal
fedlions of the common officinal fponge.

Plate XI.

G Is the cocks-comb fponge, taken off the rocks at
Haffings in Suffex, and viewed while alive in
. ffa-water. The other fponges, reprefented here,
are introduced to fhew the variety of forms
thefe animals appear under in different parts of
the world.

> .

Fig.F is a branched tuberculated fponge from Cape
Coaft Caftle in Africa. Fig. f reprefents the
appearance of the tubercles in their dried ftate,

when

-s I

1

i

* ■?

1‘bihs. JWoiJ-. lei. LV. TAH.XT.

sem

&>ss?w

i*

^5>v>r^

te

iMr

yu? :*4t ' A.

%

■[ 289 ]

when magnified. This fponge approaches very
near to the figure of the Corallium alhim ^porbfum
maximum of Sir Hans Sloane, fee the Hift. of
Jam. Vol. Tab. iS. fig. 3. and of the Poruj
albus ereiitor ramojiis fuberculis crebris Jurfum
fpebi antibus of Morifon. See Hift. Ox. p. 3*
Se<ft. 15. Tab. 10. fig. 3.

Fig. H is a fponge from Stavanger on the coafi: of
'Norway j'this may be called the Sea-fan fponge,
from its great likenefs to the keratophyton of
that name j all its pores are furrounded with fmall
fpiculae, whichj from their minutenefs, could
not be well repreferited in the drawing.

The dichotomous branched fponge at Fig. I is of a
firm but elafiic texture, very full of fmall holes,
guarded by minute fpines 5 this was found on
the coaft of Norway, and prefented to me by
my worthy friend Peter Collinlbn^ Efi^uire, >
F. R. S.

Vol. LV.

XXXII. Ex-

C 290,]

XXXII. ExtraB of Letter from Dr.
John Hope, Profejfor.of Medicine and
Botany in the Univerfity of Edinburgh, to
. Dr. Pringle ; dated Edinburgh, 24 Sep-
. tember, 1765. •

■ Read Nov. 7, T' N ’ autumn 1763, I received from
>7^5* Dcx5lor Mounfey the feeds of the

Rheum palmatum, which he afliired me were the
-feeds, of the true Rhubarb. I fowed them immedi-
ately in the open ground in the Botanic garden. In
the beginning of May laft, one of the plants from
thefe feeds puflied up a flowering ffem, and about the
• middle of the month, the flowers began to open, and
‘ continued in great beauty till the^Bth or 9th of June;
^ ’during this period, the wind was from the eaft, and
t extremely cold, and both the air and ground very
'dry. Thefe circumftances had a great effedt on the
flowers ; for, at their flrfl appearance one cold day,
many of them turned black, and I imagined they
would have been totally deftroyed : they recovered
however, and opened very well, and I had the plea-
fure of colledting near thirty feeds, fome of which,
I hope, will prove fertile.

I employed Mr. De la Cour to make the draw-
ings, who, though a good painter, is no botanift ;
this defedl was fully fupplied by Mr. Samuel Bard
of New York, fliudent in this univerfity, who made
the drawings of the frudfification in plate XIII. fig.
4. Uf a, bj Cf d.

I was

[291 I

I was fo much afraid the feverltyof the cold would
deftroy the flowers, that I caufed the drawings of the
plant to be taken when it was four feet high ; but in
lefs than fourteen days it grew to eight, and at that-
time was moft beautiful, with numerous and lofty
panicles of flefh-coloured flowers, and large elegant
leaves at its bafe.; It is proper to. take notice, that
the foliage at the bafe of ^ the plant delineated in
Plate XII. did not all belong to one plant, but to
two or three, which accidentally grew~fo clofe to-
gether, that it was impolTible to make a drawing of
the flowering plant fingly, without deftroying the
reft, which feemed unnecelTary, and I could, by no
means confent to ; further, the figure of the root in
Plate XIII. was not taken from the root of the flow-
ering plant, but from anothe!r fprung from the fame
feeds. On cutting this root acrofs, I found it very
fucculent, the juice a little mucilaginous and of a
fweetifh tafte. Although the root was taken up a t
great deal too young, and at an improper feafoa
(viz. in July) yet it had moft perfedfly the fmell of
the true rhubarb ; and when chewed, though it was .
at firft foft and mucilaginous, it foon difcovered ex-
adly the tafte of the beft foreign rhubarb. I have
made trials of the powder of the root in the fame
dofes, in which the foreign rhubarb is given, and i
found no difference in its effe(ftsi its operation being
equally eafy and powerful.

From the perfedt fimilarity of this root with the .
beft foreign rhubarb in tafte, fmell, colour, .and pur-
gative qualities, we cannot doubt of our being at laft '
poffeAed of the plant, which produces the true rhu-

P p 2 barb,

[ 2p2 ]

barb, and may reafonably entertain the agreeable ex-
pe(5lations of its proving a very important acquifition
to Britain.

I have fubjoined a botanical defcription of the
Plant.

Rheum Palmatum Linn. Sp. PL RJmbarbarum 'cerum

Med.

.Radix ramofa perennis.

.Folia radicalia (ad i6) bipedalla, petiolata: petioli
pedales teretes, fuperne fubplani, glabri, viridis,
vcoloris, fed in quibufdam partibus maculis par-
vis anguftis purpureis notati, in aliis penitus fere
purpurei. Hi petioli, quffunt pedales, ad bafinfo-
liorum definunt In 3 vel 5 coftas inferne promi-
nentes j folia ipfa funt ovata, profunde incifa,
laciniis acutiufculis j pagina fuperior eft viridis,
inferior alboviridis, ambas fcabriufcula3»
vCaulis eredus, fubteres, fiftulofus, articulatus, vagina-
tus, glaber, obfolete ftriatus, odtopedalis 2 uncias
ad baftm in latitudinem patebat. 14 articuli,
quorum finguli a parte infima ufque ad nonum
unico folio reflexo inftrudli fuerunt. Haec folia
funt alterna, & fuperiora gradatim minora, petio-
lufque ad fuam bafin, vaginam membranaceam
caulem cingentem format.

Pedunculi plures ex alls foliorum prodeunt
fuberedti, inasquales (quorum medius caeteris
duplo longior), ftriati, teretes, ad bafim planiuf-
culi, exque horum lateribus alii pedunculi ft-
2 mill

//■/i /iurOM;

» J

r

■I

\

•

[ 293 ]

mill modo dividend!, vel fimplices tenues pedicelli
fuftentantes nudum florem^

Confer Linnaei Genera plantarum de defcriptione par-
tium fmdificationis quae apprime in hanc eon-
venit.

Sapor, odor, & color radicis eadem ac in radice exotica.

Florum fapor aftringens, herbaceus, fubacidus j odor
nullus.

Foliorum fubftantiae fapor fubamarus, aftringens, her-
baceus ; coftarum fapor acidus, fubamarus, &
proprium aliquid valdeingratum, non facile ver-
bis exprimendum, exhibens. Caulis fapor debilis
fubacidus.

Tab. XII. Rheum palmatum florens exhibet.

Tab. XIII. Fig. i. radicem magnitudine naturali di-
midio minorem exhibet.

Fig. 2. plantain flores & folia caulina ex-

pandentem exhibet.

I. ■ Fig. 3. folium fextuplo minus foliis radica-
libus plantae exhibet.

Fig. 4. pedunculus communis magnitudinis

naturalis eft.

aaa b piftillum (fed non fatis explica-

tum) ; c femen maturum ; d fedionem tranf-
verfam gufdemexhibent, magnitudine naturali.

XXXIII, A

[ 29+ ]

Received January 31, 17^5.'

XXXIII, Memoir y containing ' the Hijlory

of the Return of the famous Comet of
1682, with Obfervations. of the fafne,
made at Paris, at the. Marine Obferva-
tory, in January, February, March, April,
May, and the Beginning of June, 1759,
By Mr. Meflier, AJironomer, Keeper of the
Journals, Plans, and Maps belonging to the
Marine of France, Fellow of the^ Royal
Society in London, and Member of the
Society of Sciences in Holland ; tranfated
from the French by Matthew Maty,
M,D. Sec.R,S.

65"’ T X the predidions of the heavenly phas-
‘ X nomena, which depend on the mo-
tion of the ftars, two things are to be confidered,
viz. the time and place. As to the time, when the
velocity and diredion of the ftars in their motions
both apparent and real are known, the time of their
different appulfes and afpeds may always be fore-
told, and the accuracy of the calculations depends
on the exadnefs with which their velocity and their
feveral inequalities are afcertained. Now it is well
known that all the former uncertainty, as to the exad
time of the return of the comet foretold by Dr.
Halley, was owing to the variations it muft have un-
dergone from its leveral fituations and approximations
to the planets in its progrcfs thro’ the folar fyftem.

Dr.

[ 295 ]

Dr. Hallejr, who was firfl aware of the unequal
returns of this comet in its former appearances,
which he found to have been alternately of 75 and
'76 years, was likewife the firft who alhgned their
true cauie. He afcribed it, as T faid above, to the
nearer or more diftant approaches of the planets of
our iyftem ; and having obferved that the comet we
are fpeaking of came very near Jupiter in the
fummer of 1681, above a year before its laft ap-
pearance, and remained feveral months in the neigh-
bourhood of that planet, he judged that circum-
ftance alone fufficient to have coniiderably retarded
its motion, and prolonged the duration Of its revo-
lution. Hence he concluded that its return was not
to be expedled till the latter end of 1758, or the
beginning of the next year.

Dr. Halley obferves, in confirmation of this opi-
nion, that the adion of Jupiter upon Saturn is alone
fufficient to alter the duration of Saturn’s period one
whole month ; and he adds, how much greater ir-
regularities muft not a comet be liable to, which at
its remotefl diftance gets near four times farther
from the fun than Saturn, and whofe velocity in
drawing near the'fun needs but a very fmall increafe
to change itselliptic into a parabolic curve.

Dr. Halley does not determine more exadly the
time of the return of the comet of 1682; neither
could he do it but by determining exadly the effed
of the neighbourhood of Jupiter, which muft very
fenfibly affed the velocity with which the comet was
moving towards the fun. Befides, regard muft be had,
not only to this approach to Jupiter in 1681, but
likewife to the other approaches to this and all the

other

[ 296 •]

other planets, which aft more* or lefs upon the
comet, as they do upon each other. In lliort, it
was neceffary to confider all the different lituations
and diffances of all the pJanets with regard to the
comet, during the whole of its laff revolution, and
even during the former ones, when the returns had
been found to be unequal.

What immenfe labour ! and what geometrical
knowledge did this tafk not require? Mr. Clairaut,
of the Royal Academy of Sciences, undertook it;
and his refults differed but one month from the ob-
fervation. No fraall degree of exaftnefs this, con-
hdering the immenfity of the objeft. In November
1758, he publifhed his conclulion, which allowed
about 618 days more for the period that was to end
in 1759 than for the former, whence he inferred
that the comet muff be in its perihelion towards the
middle of April. He added, however, {journal des
S^avajis^ Jan. 1759) “ Any one may think with what
“ caution I venture upon this publication, fince fo
** many fmall quantities unavoidably neglefted by
“ the methods of approximation may very poflibly
“ make a month’s difference, as in the calculation
“ of former periods.” It accordingly proved fo, the
comet having reached its perihelion on the 1 3*^ of
March in the morning. Mr. Clairaut has fincc
publiflied the methods and calculations, by which he
has arrived at this conclulion.

The impatience of aftronomers, and their defire
to prepare for verifying this prediftion of Dr. Halley,
had put them upon enquiring for feveral years in
what part of the heavens this comet was likely to
appear ; but, being ignorant of the exaft time of its

return.

[ 297 ]

return, they could not determine the fpot where it
might be expeded to be feen, but by making various
fuppofitions as to the time of its perihelium. This
Mr. Dirck of Klinkenberg, a famous aftronomer.
Member of the Society of Sciences in Flolland, and
a correfpondent of the academy of Paris, had at-
tempted feven or eight years before, having taken the
pains to calculate the principal points of fourteen dif-
ferent tracts, which the faid comet was to take, upon
as many different fuppofitions relating to its paffage
thro’ its perihelium, almoft from month to month,
from the 19^*^ of June 1757 to the 15^^ of May

1758. Meffrs. Pingre and De la Lande proceeded
much in the fame manner in the calculations they
publifhed in the Memoirs of Trevoux for April

1759, firfl and fecond parts, with this difference,
that the latter in their fuppofitions had taken nar-
rower limits, and nearer to Mr. Clairaut's determi-
nation, who, as I faid before, had fixed the return
of this comet to the middle of April.

Mr. De L’lfle, being curious of feeing the comet
on its firfl return, as foon as it could be difcovered
by means of refrading or refleding telefcopes, be<-
fore it was vifible to the naked eye, thought he
mufl proceed in a different manner from what other
aflronomers had done, to find out in what part of
the heavens it mufl be looked for. He confidered that
it was not neceffary to know its place throughout its
■whole courfe, but only at the firfl moment of its
appearance, becaufe, having once found it out, it
would be an eafy matter afterwards to trace it thro’
its whole progrefs by obfervation and calculation.

VoL, LV.

A full

[ 298 ]

A full defcription of this method is to be found
in an ample memoir concerning this comet, which I
have laid before the Royal Academy of Sciences at
Paris, and which no doubt will be printed in their
collection, together with a northern hemifphere, by
means of which I have been enabled to look for
this comet in the very place of the fky, where it
ought to appear j and it was by the help of this
planifphere that I actually difcovered the comet from
the marine Obfervatory at Paris on the 21ft of Janu-
ary in the evening, after fearching for it two years
fuccellively whenever the fky would permit. The
weather was extremely clear the 21 ft of January the
whole day and evening. I feized this opportunity,,
and as foon as the ftars were vifible after fun-fet, I
examined, thro’ a Newtonian telefcope of four feet,
and a half, thofe places of the flcy, where my plani-
fphere fhewed that the comet was to be expeCted.
After much pains, I perceived about feven o’clock a
light refembling that of the comet I had obferved the
year before in Auguft, September, October, and the
beginning of November I immediately made a
configuration of this new light wdth relpeCt to the
neighbouring ftars, in order to examine the next
night w'hether it had had any motion among the fixed
ftars. This light appeared pretty large ; and in the
middle I obferved a nucleus, or bright fpot, which
was no proof as yet that it was a eomet, as there are
fome nebulous ftars, with a bright fpot in the middle.
By the drawing I took of this new light with refpeCt
to two neighbouring ftars, one of which was the
1 8th of Pifees, according to Flamflead’s Catalogue,
* See Mem. dc I’Acad. Roy. des Scicnc. An. J759.

2d

[ 299 1

2d edition, of the 5th magnitude, marked with the
Greek letter a, the other a new ftar of the 8th mag-
nitude, which I afcertained by oblcrvation, by com-
paring it with the above-mentioned ftar a of Pifces,
its right afcenfion for the prefent time being 352b
5". and its declination 1°. 6h 40'' N. and is
the 28th in the catalogue of the ftars which have ferved
to find out the pofition of the comet, which is to
be feen at the end of this memoir ; at 6'\ 56' true
time, the pofition of the comet in right alcenfioii
was eftimated at 352°. 15^ declination

i”. 32'. 6'h North-.

Jan. 22, at the fame hoar as the day before, the
iky being equally clear, I again faw the fame light
with the 44 foot telefcope, and found it had fenfibiy
changed its^ place, but its appearances were the fame.
From this iecond obfervation I no longer doubted of
its being a comet ; and from this very night I began to
take notice of the fituation of the nucleus, by com-
paring it with a fmail new ftar which is not to be
found in the catalogues, nor in the celeftial maps of
Flamftead, but is that whofe pofition I have juft now
mentioned, and which ftands N 28 in the catalogue
annexed to this memoir. It was not. without fome
difficulty that 1 could take the pofition of the comet
with regard to this little ftar, becaufe 1 was obliged
to throw light upon the threads of a filk micrometer,
which was adapted to the Newtonian telefcope, f^ur
feet and a half long, and the leaft degree of ligiit
from a wax candle 1 made ufe of, prefently made
both the comet and the ftar difappear. The pofition
of the comet may be feen in the fecond table here-
unto annexed, and like wife all the other pofitions of

Q^q 2

C 30-0 ]

it, which have been determined to the time of its
final difappearing.

The 23d, the fky being very clear, I again faw
the comet ; its appearances were the fame as the
two preceding days. I compared the nucleus with
a very fmall ftar, only of the loth magnitude,
which I have fettled by comparing it with the 46th
ftar of Pifces of the 6th magnitude,, according to
Flamftead’s catalogue. See the pofition of this flar
in the firft table, N° 27. The pofition of the comet
is fet down in the fecond table.

The 24th in the evening, the fog, thin clouds,
and vapours about the horizon fuffered me to take
but an imperfedl view of the comet j all I could do
to get at its fituation was to obferve the differences
of azimuths and heights of the comet, and the two
ftars of Pegafus called Algenib and Markab. Thefe
differences did not appear to me to be fo exadt as to
depend upon the determination of the comet from
them, fo I fhall give no account of them.

The 25th in the evening, the flcy being clear at
times, I again faw the comet ; its light was increafed,
and the nucleus looked brighter than before, but
without any appearance of a tail. I compared it
diredlly with a ftar which is the i6th of Pifces, in
the order of Flamftead’s catalogue. It was likewife
compared with N° 26 of my table. The comet was
fufficiently vifible this night to be feen thro’ a com-
mon two feet telefcope, and even thro’ one of a
fingle foot. At four minutes pafl feven, the comet
was ftill to be feen thro’ the telefcope at the height
of 13° above the horizon.

The

[ 301 ]

The 26th, the cloudy weather prevented my fee-
ing the comet ; but the 27th, the fky being tolerably
clear, tho’ the air was not altogether free from va-
pours, I again faw the comet, but could form no
judgment of its appearances. I compared the nu-
cleus with a new ftar which is the 25th of my table,
which I knew by comparing it with fome ftars in
Flamftead’s catalogue. I alfo diredly compared the
nucleus of the comet with the i6th fiar of Pifces,
See the fecond table.

The 28th, the Iky being pretty clear in the even-
ing, I began to fee the comet at 264. above the ho-
rizon ; but the air was fo much darkened by fome
fire- works which had juft been played off at the Prince
of Conde’s, that I could neither judge of its ftiape
or brightnefs. All I could do was to compare it
three times with the new ftar mentioned above, N°
25 of my table, and once with the i6th of Pifces.

The 29th and 30th it was too cloudy to fee the
comet, but the 31ft it cleared up a little j the comet
appeared between the clouds, though not plain enough
to judge of its increafe, but only to compare it with two
ftars, which are not in Flamftead’s maps, nor men-
tioned in his catalogue, but are not far from the ftar'
k of Pifces of the 5th magnitude, with which I
compared them. They are both fet down in the
firft table, N° 23 and 24.

February i, the fky being perfedtly clear in the
evening, the comet appeared, notwithftanding a
ftrong twilight and the neighbourhood of the moon.
I compared the nucleus with the fame two new ftars,
N° 23 and 24. The clearnefs of the air this night
induced me to meafure the diameter of the coma of

the

1

[ 302 ]

the comet with the micrometer adapted to the New-
tonian telercope, and I found it 2 min. and I
likewife determined the magnitude of the nucleus,
which I found to be 20'', having compared it with
the thicknefs of one of die threads of the microme-
ter, which I afterwards reduced into parts of the
micrometer. The twilight was then fuch as to fa-
vour this meafuring and the other obfervations.

The 2d the clouds prevented my feeing the co-
mer, but the 3d, about feven o’clock, the fky being
tolerably clear, the comet appeared, though but
faintly, by reafon of its nearnefs to the horizon and of
the light of the moon ; however, I compared it with
a ftar of Pifces that is to be found in Flamftead’s
catalogue. It is the 8th of that conftellation, marked
with the Greek letter y!. The pofition of this ftar
for the prefent time is ftiewn in the firft table.

The 4th I was as much hindered as the night
before by the comet’s nearnefs to the horizon, and
by the too great light of the moon, which made
it impotfible to judge of its increafe. I compared
the nucleus with the fame ftar y of Pifces.

From the 4th to the i ith it was utterly impoflible
to make any obfervations, or even to fee the comet,
by reafon of the clouds which darkened that part of
the fky at the time it fhould have appeared. The
nth the ftcy was clear in the evening. I faw the
comet, which was but io° high, fo that I could not
judge of its appearances, from its nearnefs to the
horizon, and the ftrong light of the moon, which
was then at the full. 1 was likewife much obftruefted
by the height of the chimnej's which ftand between
the horizon and the marine Obfervatory to the Weft.
4 This

[ 303 ]

This prevented my comparing the comet with the
neighbouring ftars for a quarter of an hour that
it continued vifible. All I could do was to draw the
configuration of thefe ftars with the comet, both
with the four feet and half telefcope and with a little
two feet refrading telefcope, which was faftened
over the refledor in a parallel fituation. From this
configuration, I have edimated the pofition of the
comet, as is feen in the fecond table.

The 1 2th, the Iky, which had been cloudy all day,
cleared up a little in the evening. The comet ap-
peared near the horizon for a few minutes, but was
foon hid behind the chimneys. All I could do was
to eftimate its pofition relative to the neighbouring
ftars.

The 13th, the fky was quite overcad; but the
14th having cleared up in the evening, I could fee
the comet, but clofe to the horizon, at the height of
6° for a few minutes j and it foon difappeared, be-
ing intercepted by terredrial objeds too high above
the horizon, and which I could not keep clear of.
All I was able to do in the fhort interval it was vi-
fible, was to take a hady edimate of its pofition with
refped to the dar A of Pilces, The brightnefs of
the twilight prevented my feeing the comet earlier.

The 15th and the 17th, the fky was pretty clear
in the evening ; but I could not fee the comet at all,
becaufe of the bright twilight, which continued till
the fetting of the comet.

The comet being no longer vifible at night, on
account of its getting into the fun’s rays, Mr. De
L’Ide and I examined the exaded obfervations I had,
made, which helped us to determine the time and

the

[ 304 ] .

the place of the {ky, where it was to re- appear in
the morning, when it fhould get clear of the rays of
the fun. This was to happen towards the end of
March ; but the cloudy weather, which prevailed at
Paris during' that month, prevented our feeing it
again. Behdes this inconveniency, the marine Ob-
fervatory did not ftand high enough to fee it at its
firft rifing in the morning. We were obliged to
look out for a more convenient place in the neigh-
bourhood, and met with one at the houfe belonging
to the College of Lewis the Great, where there is a
turret which overlooks all the horizon, and where Fa-
ther Mervilie, Profeflbr of Mathematics, makes his
obfervations. The 3 td of March I removed thithei
my 4I feet Newtonian telefcope, and likewife a
pendulum clock.

I Ipent the night from the 3 id to the id of April
in this turret with Mr. De L’llle. At three in the
morning, 1 began to trace a meridian upon the door
by means of a fea-compafs j and I likewife drew a
line, which made an angle of about 74° with the
meridian, from the South towards the Ead, in the
direction of which the comet was drd to appear. I
directed the Newtonian telefcope according to this
linei and at 52 minutes pad three I faw the comet,
about two degrees above the horizon. It appeared
much larger and brighter than in the middle
of February ; and indeed it was but 18 days pad its
perihelion. Now it is well known that comets are
much brighter after the perihelion than at the fame
didance before it. Befides, the comet after pading
the perihelion was as near again to the earth as on
the 14th of February, when I lod fight of it at

[ 305 ]

night. When I faw this comet again on the ift of
April, I could very plainly difcern its tail, but could
not afcertain its length, becaufe of the morning twi-
light which was then beginning, and Toon increafed
much ; it filled the field of the telefcope, and muft
have extended far beyond. According to what I
have obferved, the tail of the comet muft have fpread
to more than 25 degrees. The nucleus was confi-
derable, but not well terminated, and it apparently
exceeded the fize of ftars of the firft magnitude. It
was of a pale whitifh colour, not unlike that of Ve-
nus. The nebulofity which furrounded the nucleus,
and went on lefteni ng, ftiewed reddifh colours, and
thefe colours grew more vivid towards the brighteft
parts of the tail. The morning twilight, which in-
creafed apace, foon put an end to thefe appearances,
and afterwards made the comet itfelf difappear j
however, I had been able to perceive it with the
naked eye when it was fomewhat difengaged from
the vapours of the horizon. In this fhort interval,
I had but juft time to obferve the flaape of the comet
with the telefcope, and to compare the nucleus with
a ftar which I have fince found to be the 30th of
Aquarius, according to Flamftead’s catalogue, where
it is fet down as of the 6th magnitude. The differ-
ence of declination between the comet and this ftar
was only eftimated. The true time of this obferva-
tion, which will be found in the fecond table, has
been concluded only by means of a minute watch,
which had been fet to the true time in the evening by
the clock of the marine Ohfervatory. This was
likewife the cafe with refpetft to the obfervations
made during the month of April, in the turret of
VoL. LV. R r the

[ 3o6 ]

the College of Lewis the Great, where there was a
pendulum clock, as I faid before, fet by a watch which-
was regulated every day of obfervation.-

I faw the comet the, 2d of April in the morning;,
a little before four o’clock, about 4.°- above the hori-
zon. The tail did not then appear" fo plain as the-
day- before. Whether the twilight was ftronger, of"
the horizon- more incumbered with vapours, 1 could*
fee none of thofe colours in the tail which' Lhad ob-
ferved’ the day before. I compared the nucleus in>
the twilight with a fixed ftar which' was nearly in the
fame parallel with the comet j it is the 2 2d of
the firfi: table, and I judged it to be of the yth^
magnitude.

The 3d, 4th, and 5th, I faw nothing of the comet ;
but on tlie 6th in the morning I looked* for it through
the telefcope, as it, was no longer vifible to the naked
eye, from the great ftrength of the twilight at its
.firffc rifing. 1 began to fee it at above a quarter after
four, about 6° above the horizon. I compared the
nucleus with a new ftar, which I have judged to
be of the 7th magnitude. Its pofition at that time
is let down in my firft table, N° 21.

April 7, in* the morning, the fky not being per-
fedlly clear, I faw the comet a little before four ; the
appearances were not fo plain as for fome days paft.
1 compared the nucleus with a new ftar which I jud^
to be of the 7th magnitude. The determination of
this ftar may be feen in the firft table, N° 20, and
that of the comet in the fecond.

The 8th in the morning, the ftcy being almoft
totally overcaft, I faw the comet for a few minutes
through fome little intervals of the clouds, at near qt*"

above

[ 307 1

above the horizon. All I could do towards afcer-
taining its pofition, was to eftimate it with refpedt to
the new ftar of the day before, N° 20.

The 9th, at 4^ 23' in the morning, I again faw
the comet through fome thin clouds j but the fhort-
nefs of the time it was vihble did not permit me to
take its pofition.

The loth, I ith, 12th, and 13th, in the morning,
the clouds prevented my feeing the comet ; but hav-.
ing on the 13th removed my inflruments to a place
ftill better fituated than the turret of the college,
though in the neighbourhood, I carried on my ob-
fervations there till the 2d of May.

April 14, in the morning, I faw the comet again,
the iky being very clear, without a cloud, and I was
only obfi:rud;ed by the great light of the moon, which
had pail the full on the 12th at one in the af-
ternoon. The brightnefs of this and the twilight
prevented my feeing the comet at its firil rifing. I
could fee nothing of it till three quarters paft three,
when it was got about 4** above the horizon. It
was hardly to be feen, and the nucleus could not be
difiinguifiied from the coma, fo that the comet
looked but like a faint round fpeck of light. It was
then near the fiars of the 3d and 4th magnitude,
called by Bayer y and ^ of the tail of Capricorn,
pretty clofe to the weilermofi: of thefe two ftars. 1
had not time to take the diflance by the micrometer,
the twilight having quickly made the comet difap-
pear. All I was able to do, whilft it was vifible,
was to determine its fituation with tolerable exadtnefs,
by means of the differences, azimuths, and heighths
of the comet, and the two ftars of Aquarius’s flioul-

R r 2 ders.

[ 3o8 ]

ders, and to eftimate the pofition of the comet with
refpedl to the ftar J of Capricorn. I have fet down
this eftimate in the fecond table. It is more to be
depended on than the determination by the azimuths
and heighths.

In the night between the 14th and 15th, it being
cloudy mod: part of the night, I faw the comet be-
tween the clouds ■, but the twilight and the moon
prevented my obferving its appearances. The nu-
cleus was but imperfedtly terminated, and furround-
ed with a whitiih nebula of fmall extent. I compared
the comet in right afcenfion with the dar ^ of Capri-
corn. The difference of declination was only edi-
mated. At 19 min. pad 4, the comet difappeared
in the twilight, being then but 8° above the horizon.

The weather was overcad in the morning of the
1 6th j but the 1 7th, the fky being perfedlly clear,
the comet began to appear foon after three quarters
pad three in the morning, being but about above
the horizon. It was hardly difcernible, on account
of the twilight and the height of the moon, and
appeared fainter dill than the 1 5th. I compared the
nucleus with two dars that were near it. Thefe dars
are new ones. I determined their pofition for the
prefent time, which will be found in the fird table,
N° 18 and 19. The hrd was edimated of the 7th,
and the other of the 8th magnitude.

The 18th and 19th in the morning, the fky being
very clear, I looked for the comet, but could not
difcover it. The great latitude it was advancing to
every day left no room to hope it would be feen any
more above our horizon in the morning ; but we
knew the trait it was to follow in the heavens. It

3

was

[ 309 ]

was to rife again above oar horizon, after having run
through feveral fouthern conftellations with prodigi-
ous velocity, and approached the South Pole within
15 degrees. The fouthern conftellations, through
which the comet was to pafs after coming out of
Capricorn, were the Indian, the Peacock, the Bird
of Paradife, the Crofs and the Centaur, from whence
it was to traverfe the Hydra with a motion almoft
perpendicular to the horizon, and finally be loft in
the Sextant which lies under Leo. It was only in
this laft conftellation that it was to difappear from
our horizon j and I was preparing for feeing it again,
taking the fame precautions I had ufed to defcry laft
years comet, when it was diftant from the fun above
twice and a half as far as the fun is from the earth.
Hence appears the utility which will arife from thefe
laft obfervations compared with the former made five
months before, for afcertaining the true elements of
the theory of this comet in this new apparition, and
chiefly to find out the alterations which have happened
in thefe elements fince the apparition of 1682. They
will help us to difcover more certainly and demon-
ftratively the effedt of the adion of the planets upon
comets.

Having thus ceafed feeing this comet on the 17th
of April in the morning, as I before obferved, I was
eager to feek for it again towards the end of this
very month of April, in that place of the flcy where
I had calculated it muft then appear in the evening ;
but the bad weather prevented my feeing it till the
29th, when I perceived it near the horizon, through
thin clouds, but I was notable to take its pofition. Tlie
30th the Iky was quite cloudy j bvu on the firft of May

1 faw

C 310 ]

I faw the comet with the naked eye about nine
o’clock at night, coming out of the clouds which
overcaft the horizon, but which difperfed foon after.

It appeared to the naked eye larger than the ftars
of the firft magnitude, the nucleus furrounded with
a great coma. Its light was but faint, like that of
the planets feen through the thick vapours of the
horizon. It would have appeared brighter but for the
light of the moon, which probably prevented my
taking an exaft eftimate of the fize of the comet.
The nucleus appeared pretty diftindl in the middle
of the great nebulofity which furrounded it, and
fpread more to the Eafl: by one degree and a half.
The fame night, May ift, I compared the nucleus
of the comet with two new ftars that were juft by,
which I found to be of the yth and 8th magnitude.
I determined the pofition of one of thefe ftars by
obferving it at the meridian with known ftars. Its
pofition may be feen in the table, N° 17. All the
obfervations lince the 14-th of April in the morning
were taken from the place I mentioned, near the
College of Lewis the Great. The clock I made ufe
of for thefe obfervations had been fet to the true
time only by a minute watch, which I had taken care
to fet by the clock at the Obfervatory, fo that there
may be an error of fome minutes in the true times
of the obfervations. As I found by this day’s ob-
fervation that I could obferve the comet the follow-
ing days from the marine Obfervatory, I caufed the
Newtonian telefcope to be removed thither, as like-
wile the clock, which however was of no further ule
for thefe obfervations, having from this time made
ufe of that of the Obfervatory, that is fet by the
’ ‘ motion

C 311 ]

motion of the fixed fiars, and goes extremely regu-
lar, So that all the remaining obfervations, down to
the total difappearing of the comet, were taken at
the marine Obfervatory.

May 2d was quite cloudy; but the 3d, the wea-
ther clearing up at night, 1 faw the comet between
two new liars of the 8th and 9th magnitude. I de-
termined their pofition for the prefent time by com-
paring them with the liar ^3 of the Hydra in Flam-
Head’s Catalogue. The nucleus of the comet I com-
pared with thefe two new Hars, which may be feen
in my firll table, N° 14 and 15. That night the
comet was dillindly feen with the naked eye ; it
looked like a little cloud of light, in the center of
which was a luminous point, which was the nucleus,
and appeared tolerably well terminated ,when feen
through the Newtonian telefcope. The moon, which
was now in her firll quarter, confiderably obllrudted
the appearances of the comet; notwithflanding which,
we could dillinguilh a tail about one degree and a
half in length, tending to the Ball.

The 4th was overcall ; but the 5th being perfedly
clear in the evening, I faw the comet, but could
form no judgment as to its appearances, becaufc of
the moon-light. I compared the comet with two
Hars of FlamHead’s Catalogue, which are the iH
and 2d of the Hydra, both marked with the Greek
letter (p‘ and (p^, the firfi of the 6th magnitude, the other
of the 5th. The pofitions of both thefe Hars for the
prefent time may be feen in the firH table.

The 6th I again faw the comet. The moon-light
Hill prevented afcertaining its real fize. I compared the
nucleus with a new Har, which I judged to be of the
I 7th

[ 312 ]

7th magnitude. I determined its pofition by obferv-
ing it feveral times on the meridian. It is to be
found in the fird. Table N® 12.

The 7th I compared the nucleus of the comet,
with a new ftar, which I eftimatedof the 7th magni-
tude. I determined its pofition for the prefent time
by comparing it with the ftar of Hydra of the
5th magnitude. The pofition of this new dar may
be feen in my fird Table N° 10.

■ The 8th I did not fee the comet till it was 24'’
above the horizon. I compared its nucleus with a
new dar, which I edimated of the 9th magnitude.
I found its pofition by comparing it with fome dars.
It dands in the fird Table N° 1 1.

The 9th quite clear at night. The comet was
upon the parallel of a new dar, which I edimated
of the 7th magnitude. I determined its pofition for
the prefent time, by obferving it feveral times on
the meridian. It is fet down in the fird Table
N° 13.

The loth and i ith were cloudy evenings, but the
1 2th quite clear till 1 1 at night. I faw the comet,
but the full moon greatly lefiened its appearances.
I compared the nucleus v/ith a new dar, which I
edimated of the 6th magnitude. I found its pofi-
tion for the prefent time, by comparing it with lome
known dars. It is fet down in the fird Table
N" 16.

The 13th the ficy was cloudy almod all day, and
at night ; however, I faw the comet in the vacancies
between the clouds. The moon was not yet up.
The appearances of the comet were plainer than
the night before. It was but jud difcernible by the

naked

C 313 ] .

naked eye. I compared the nucleus with fonie very
rmall ftars, one of which I found by comparing it
with fome ftars of the fextant. The pofition for
the prefent time ftands in the firft Table N° 8.

The 14th clear at night, I faw the comet with
the naked eye before the moon was up j it was ftill
equal to the ifars of the 4th magnitude. I deter-
mined the apparent diameter of the nucleus, which
I found to be 27 feconds, by comparing it with the
thicknefs of one of the threads' of the micrometer,
which was adapted to the Newtonian telefcope. I
then compared the comet with lev^eral ffars, namely
with tv/o new ones, which may be feen in my firft
Taole N° 6 and 7, and with the 22d of the fextant
in Flamftead’s catalogue.

The 15th the iky was quite clear at night. I faw
the comet very plain by the naked eye, but could
perceive no tail 3 but I obferved one in looking through
a refracting telelcope one foot long, made of convex
glaffes, which is very clear, and difcovers a great
compafs of the fliy. I made ufe of it to find out the
flars which correfponded with the extremity of the
tail, and then I determined the pofition of thefe
ftars with the comet, by means of the micrometer
adapted to the telefcope, which gave me the length
and direction of the tail. I found it to be 3"^ JL long.
This tail was not vifible with the reflecting telefcope,
no doubt by reafon of its too great magnifying powerj
it only fliewed a round and indeterminate light fur-
rounding the nucleus of the comet. I compared
the nucleus with the 2 2d flar of the fextant ; the po-
fition of this fl:ar may be feen in the firfl Table.

S f

VoL. LV,

The

C 314 ]

The 1 6th,. the fky being as clear as the night be-
fore, I faw the comet till its fetting. The tail ftill
appeared to me of the fame length. The nucleus
was again compared to the abovementioned 2 2d ftar
of the fextant.

The 17th, the fky being clear, I began to fee the
comet as foon as it was dark. I again faw the tail
through the one foot glafs, and found it 4° long. I
compared the nucleus with the fame ffar as before, and
with two new ones N° i and 2 of the firft Table, one
of the 6th, and the other of the 7th magnitudei
1' determined their pofitions for the prefent time.

The i8th, the fky being perfedly clear in the '
evening, L faw the comet through the one foot
glafs. The tail appeared a little incrcafed, but its
light was very faint, and it v/as with difficulty I
could perceive it at all. I compared the nucleus with
the two new ftars N° i and 2. - The pofitions for the
prefent time may be feen in the firft Table*

The 19th ftill a clear fky. 1 faw the comet as
foon as it was night j its appearances were the fame
as the evening, before. I took the pofition of
the nucleus, by comparing it with the above ftars
N® I and 2.

The 20th the Iky was clear in the evening, though
with fome thin vapours in the atmofphere. The tail
of the comet was not fo plain to be feen as the
night before. The nucleus was leflened and indeter-
minate j I compared it with the new- ftar N® 2 of
the preceding nights, and with two other new ones
N® 3 and 5 of the firft Table, which I afeertained
by comparing them with fome ftars of the fextant.

2

The

[ 315 ]

The 2 rft, the fky being clear and cloudlefs, I faw
the comet, and compared its nucleus with one of the
three new ftars of the night before, viz. N° 3 in the
fil'd Table, of tlie 8th magnitude.

The 2zd I obferved that the comet vifibly grew
dim, and indeed it was now conilantly drawing
farther from the fun and earth ; its nucleus was
likewife much contradled, and not terminated. The
tail was hardly diftingui(l)able with the one foot
glafs, and terminated at the 41(1 ftar of the fextant
according to Flamftead’s catalogue. It was found
to be a little more than 4° long. The nucleus was
compared with the new ftar N° 3 of the firft;
Table.

Tlie 23d clear fky at night. I began to fee the
corftet as foon as it was dark. Its appearances were
the fame as the night before. I compared the*
nucleus with the faid new ftar N° 3 .

The 24th the fky perfe<5lly clear. I compared
the nucleus with the fame new ftar N° 3, and with
another very fmall new ftar N° 4 of the firft Table.

The 25th a fine clear fky. I faw the comet as loon
as it was dark, and compared it with the new ftar
N“ 4.

The 26th, the fky was as clear. I again faw the
comet. It has now loft much of its light, efpecially
for a week paft ; the nucleus is no longer diftindf,
and it is to be perceived through the telefcope, only by
a ftronger light than the nebulofity which furrounds
it. I compared the nucleus of the comet with the
fame ftar N“ 4.

The 27th, a fine fky. I faw the comet as foon
as the ftars appeared after funrfet. -I -could fcarcc

S f 2 diftinguifh

[ 3i6 ]

diftinguifh the tail with the one foot glafs ; I judged
it to be about 4° long. I compared the nucleus
with the fame ftar N® 4.

The 28th I could not fee the comet before 10
o’clock by reafon of thin clouds; its appearances
were greatly diminiflied ; it is no longer pollible to
f^e it with the naked eye (nor indeed has it been fo
for thefe feveral days ^ ). I compared the nucleus
with the fame ftar N° 4.

The 29th a cloudy night ; the 30th I again
faw the comet, but with great difficulty. Its light
was confiderably abated, and might be farther eclipfed
by that of the moon, which was now near her firft
quarter ; and it is to be prefumed we fhall not fee
this comet much longer. The increafing light of
the moon miifl in a few days prevent its being vifi-
'ble. I have yet been able to compare the nucleus to
a new ftar N" 9 of the firft Table. The pofition
of this new ftar has been found by comparing it
with fome new ftars of Flamftead’s catalogue.

The 3 I ft was cloudy, as was like wife the ift of June.

The 2d I faw the comet in the interftices of the

clouds, but could not take its pofition ; but the 3d

I faw it again between the clouds, where 'the fky

was perfe^ly clear. Its light was very dim, and

none but fuch eyes as had been accuftomed to fee it

could have perceived it at all. This was partly

occafioned by the neighbourhood of the moon which

was paft her firft quarter, fo that this day may be

»

* It is to be obferved here that the comet, on the 28th of
May, appeared much of the fame fizc, as when I firft difcovercd
it on the 21ft of January at night, though fomcwhat brighter.

fuppofed

[ 317 ]

fuppofed to be the period of its being vifible, at leaft
through the Newtonian telefcope of 4 ^ foot, which
I have made ufe of, and which magnifies the dia-
meter of objecfts about 66 times. I have once more
been able to compare the nucleus with a ftar of the
6th magnitude, which is the 27th of the fextant
according to Flamftead’s catalogue. Its pofition for
the prefent time is fet down in the firft Table.

I looked again for the comet the following days,
but in vain j fo that the 3d of June put a period to
my obfervations of this comet. The duration of
its appearance has been 134 days, reckoning from
the 2ifl of January, when I firfl faw it from the ma-
rine Obfervatory. All the obfervations of the comet
have been taken with the Newtonian telefcope, to
which was adapted a micrometer with filken threads,
which could be inclined every way, fo that it was an
eafy matter to bring one of the threads to the pa-
rallel of the comet j another parallel thread ferved to
take the differences of declination between the comet
and the Ifar to which it was compared. At another
thread, perpendicular to thefe, I obferved the differ-
ences of the paffages in right afcenfion of the ffars
and the comet. The field of the telefcope was about
53 minutes of a great circle.

By this account it appears, that the comet has had
three feveral appearances above our horizon, which
M. De I’lfle and I had calculated as foon as I had
made my firfi: obfervations, that is, as early as the
month of February.

The firfi; appearance of the comet was in the
evening from the 2ifi; of January, to the 14th of
February, when I ceafed feeing it by reafon of its
r entrance

[ 3i8 ]

entrance Into the rays of the fun. The fecond ap-
pearance was at the comet’s getting clear of the rays
of the fun in the morning, after the conjuncftion
with that luminary, which was to take place a few
days before its pafTage through the perihelion. I
obferved it in the morning from the ift of April to
the 17th, when it entered the rays of the fun a fe-
cond time. The 3d appearance of the comet was
expefted to begin a few days after the end of the 2d,
when the comet, after being hid below the hori^^on,
might make its appearance above it j 1 began to
fee it again on the 29th of April in the evening,
but could not take Its pofition becaufe of the clouds.
1 went on obferving it till the 3d of June at night,
when 1 faw it no more. It was then in the fextant.
'In this laft appearance of the comet above the ho-
rizon, it was obferved by mofl of the aflronomers
in Europe.

More minute accounts of this comet will be feen
in a mcmoirwhich I haveprefentedto the Royal Aca-
demy of Sciences at Paris, together with two celeflial
maps fliewing the trad of the comet through the fixed
ftars during its appearance, which I have traced ex-
actly by my obfervations. There is likewife annexed
to this memoir a colledion of all the obfervations
which have been made of this comet, by my own and
Mr. De L’lfle’s correfpondents. Thefe obfervations
have been taken, at the Hague by Mr. Dirck de
Klinkenberg, at Leyden by Mr. Lulof, at Montpel-
pellier by Mr. de Ratte, at Avignon by Father Mo-
rand, at Vienna by the Rev. Father Hell, at Leipfick,
at Rome, at Cadiz by Mr. Godin, at Lifbon by
Father Chevalier, and at Pondicherry in the Eall
Indies by Father Coeurdoux.

Expla-

[ 319 ]

Explanation of the two Tables annexed to this

Memoir.

The firft table contains the right afcenfions and
declinations of the ftars, both of the new ones and
of thofe in Fiamftead’s catalogue, for the time of the
obfervations. It appears from this table, that the
comet has furnirtied me with an opportunity of de-
termining the pofition of 29 new ftars, which were
not vet known, and which have ferved for the de-
termination of the comet. ,

The fecond table contains all the places of the
comet, as well in right afcenfion and declination, as
in longitude and latitude, concluded from its htua-
tion obferved relatively to the ftars, whether new
ones or already known. Thefe are the titles of each
column: The ift points out the days of the month ;
the 2d, the true time of each obfervation j the 3d,
the right afcenfions of the comet obferved ; the 4th,
the declinations ; the 5th, the longitudes obferved ;
the 6th, the latitudes j the 7th, the differences of
pafiage in right afcenfion of the comet and the ftars,
marked with the fign — when the comet preceded
the ftar or was to the Weft of it, and with + when
it followed the ftar or was to the Eaft. This differ-
ence, according to the fign, being either added to or
fubtra<ffed from the right afcenfion of the ftar fet
down in the firft table, with which the comet was
compared, will give its right afcenfion. The 8th
column (hews the differences of declination between
the comet and the ftars, marked likewife with
and and which, being accordingly either added

to

[ 320 ]

to or taken from the declination of the ftar with
which the comet was compared, will give its decli-
nation. The 9th column contains the magnitude of
the ftars ; and the loth, which is the lad, has Bayer’s
letters, and the numbers of the dars, either new or
taken from Bayer’s catalogue, according to their or-
der in each condellation.

The following are the elements of the comet, as
computed by MelTrs. de la Caille, Maraldi, and De
la Lande.

Place of the afcending node

Inclination of the orbit

Pkce of the perihelion —
Logarithm of the diftance at
the perihelion - — ■ .

Time of the perihelion •

Mr. de la Caille.

S. D. M. S.

Mr. Maraldi.

S. D. M. S

Mr. de la Lande.j

S. D. M. S.

I 23 49 0

17 39 0

10 3 16 0

i 23 49 41
17 35 20
to 3 16 20

* 23 45 35
17 40 14
10 3 8 10

9,766039

9,766115

9,7670848

March •>

h ' "

h ' "

12. at 13 41

at 12 57 36

at 13 39 24

Mean time,
retrograde.

at the meridian of Paris, the motion of the comet was

TABLE

Containing the right Afcenfions and Declinations of the Stars for the Time of the

fervations of the Comet of 1759, both of the new ones and of thofe of FlamfteadS j
Catalogue, which have been made ufe of to find out the Pofitions of the Comet as-
fet down in the next Table.

’ of the
Stars.

Right

afcenfion.

Declination. I

°. 5

2

1

22

2

^ r n

149 48 55
151 25 27
153 25 25

0 f 17

6 7 45 S

6 52 25
5 5° 30

S .c:
■*-»

6

6

7

A new Star, the Comet compared May 18 and 19 at night
A Star of the Sextant, Comet compared May 14, 15, 16, and i’;
A new Star, Comet compared May 17, 18, 19, and 2o

3

'53 33 8

5 '2 52

8

A new Star, Comet compared May zo, 21, 22, 23, and 24

27

153 35 49

3 10 3

6

A Star of the Sextant, Comet compared June 3

4

153 42 34

4 28 35

10

A nev/ Star, Comet compared May 24, 25, 26, 27, and 28

5

■153 42 34

5 21 5

10

A new Star, Comet compared May zo

6

153 46 21

7 53 55

8

A new Star, Comet compared May 14

7

153 47 22

7 12 32

1 0

A new Star, Comet compared May 14

8

153 57 40

8 19 29

10

A new Star, Comet compared May 13

9

154 7 39

4 1 3 20

10

A new Star, Comet compared May 30

10

154 47 30

1221 11

7

A new Star, Comet compared May 7

1 1

I C4 1:2 21

11 52 46

9

A new Star, Comet compared May 8

1 2

154 57 2

'3 39 6

7

A new Star, Comet compared May 6 •

I

156 8 56

'5 5 53

6

A Star of the Hydra 9^. Comet compared May 5

156 8 15

" I 37

7

A new Star, Comet compared May 9

2

156 43 56

15 37 3^’

5

of the Hydra, Comet coin])areJ May 5

15658 8

19 36 31

9

A new Star, Comet compared May i 3 ‘

15

157 40 41

19 21 39

8

A new Star, Comet compared May 3

16

'59 25 32

^ 34 4'

6

A new Star, Comet compared May 12

17

159 26 5

25 31 55

7

A new Star, Comet compai-ed May i

17^-

160 0 28

25 36 24

9

A new Star

18

322 3 15

20 52 19

8

A new Star, Comet compared .‘\pril 17 in the Morning

*9

322 25 3

1 20 41 56

7

A new Star, Comet compared Aprii 17 in the Morning

4

[ 322 ]

Continuation of the T able of right Afcenllons and Declinaliona,

'S •

Right

Afcenfion.

Declination.

! O ^
, ^

0 / //

0 / //

C5j

4-*

i 49

323 2; 33

17 12 3

3

^of Capricorn, Comet elHmated April 14 and 13 In the Morning

20

325 10 5

11 26 3

7

A new Star, Comet compared April 7 and 8 in the Morning

21

326 12 50

9 42 0

7

A new Star, Comet compared April 6 in the Morning

30

327 41 29

7 40 52

6

A Star of Aquarius, Comet compared April 1 in the Morning

1 22

329 11 24

8 41 31

7

A new Star, Comet compared April 2 in the Morning

5

344 4 32

0 48 oN

6

A of Pifces, Comet compared and eftimated February 14

. 33

348 33 20

I 7 28

8

A new Star, Comet compared January 3 1 and February i

8

348 38 36

0 3 40 S

5

yJ. of Pifces, Comet compared February 3 and 4

; 24

348 49 JO

0 32 29 N

8

A new Star, Comet compared February i

2?

349 40 34

1 I 14

8

A new Star, Comet compared January 27 and 28

26

350 44 16

0 30 36

10

A new Star, Comet compared January 23

: ^7

350 52 16

1 5 8

10

A new Star, Comet compared January 23

' 16

331 0 I

0 44 48

6

A Star of Pifces, Comet compared January 23, 27, and 2$

28

352 13 5

1 6 40

8

A new Star, Comet compared January 21 and 22

i8

332 26 6

0 23 53

5

A of Pifces, Comet eftimated January 21

T ABLE

II

[ 323 ]

TABLE II.

(Containing the Places of the Return of the famous Comet of 1682, dlfcovered at the
Marine Obfervatory at Pijw, January i759» the Evening, in the Conhellatlon
of Pifces : concluded from its Situation obferved with refpeft to the Stars of the
former Table.

*759-
t'an. 21

22

Tr. Tim.

h / /

6 40 0

6 56 0

6 51 20

r. afcenfion
obferved.

0 f ft

352 15 58
352 15 47
351 51 5

Declinat.

obferved

Northern

0 / n

1 32 58

I 32 6

1 29 33

Longitude

obferved.

C t ff

1423 30 48
23 30 37
23 6 32

23

7 5 37

351 26 31

CO

22 42 16

7 10 9

351 26 1

25

6 58 54

350 38 9

I 13 57

21 53 10

769

350 39 I

769

350 39 I

1 14 30

21 54 8

27

6 22 31

349 54 47

I 4 48

21 931

6 38 0

349 53 I

I 4 36

21 7 51

7 6 I

349 52 0

I 4 52

21 659

28

6056

349 33 1

6056

349 32 54

0 59 54

20 47 23

6 21 50

349 32 I

0 59 44

20 46 38

6 21 50

349 31 46

0 59 38

20 46 25

31

6 57 28

0 45 I

7 15 31

348 25 40

0 44 25

19 39 12

;bb. I

5 48 12

348 5 35

0 40 25

19 19 4

5 50 20

348 5 42

3 i;2 26

348 5 50

6 52 40

348 5 30

0 39 57

19 18 46

3

7 6 46

347 25 6

0 3 1 20

18 38 3

1. 4

6 39 56

347 5 6

0 26 58

18 17 52

j I

6 31 30

344 42 20

0 2 20

15 56 2

12

6 20 0

344 18 50

060

15 30 59

14

6 30 0

343 4^ 20

0 15 47

14 52 22

I -^-31.

16 17 0

328 0 33

8 25 36

XC'27 16 40

Latitude DifF.
obferved
Northern

O t ff

in r.
afcenfion
from the ,

4 29 440 2 53 +

4 31 260 10 19
4 36 260 22 o

4 42 23
4 50 S3

4 51
4 59 34

34 15 +

33 45 +
21 52

o

00

5 o 5
5 o 43

21
5 I
13 53 +

I 7 o-
I 8 I-
o

7 53-

3 40°
3 47
3 51

5 15 49
5 20 o

5 19 33

5 27 28
5 31 15
640

6 5 22

6 10 47
4 15 4^

8

8

28

o-
53-;o

o 23 30—
o 27 45-

27 38-

27 30-
o 43 40-

I 13 30 —
I 33 30-

>9 4d

Differ. In

•K*

•

*

Declin.

from the ^

0

0

0

Of f/

z

0 26 18 +

8

28

New 4: . Com. eflim.

I 5 13 +

5

18

\ of 34 ■ Com .eftim.

0 22 53 +

8

28

Star above

0 20 20 +

10

27

A new Star

10

27

the fame

0 29 9 +

6

16

of Pifces

6

16

the fame

0 23 34+

10

26

New

0 3 34+

8

25

New

0 19 48 +

6

16

af Pifces

0 20 4~{-

6

16

the fame

8

25

New

0 1 20 —

8

25

the fame

0 1 30—

8

25

the fame

0 14 50 +

6

16

of Pifces

0 22 27 —

8

23

New

0 II 56 +

8

24

New

0 27 3 —

8

23

New above

8

23

the fame

8

23

the fame

0 7 28-h

8

24

New above

0 ^5 0—

5

1

■P. of Pifces

0 30 38 —

3

8

cite fame

Comet cdlmatei

.-'hHmated again

6

5

A of Pill'cs

0 .14 44 +

(7;

3*^

)f Aquarius

T t 2

Continuation

[ 32.4 ]

Continuation of the Table of the Pofitions of the Comet.

I

I

■ *759
April I

Tr. Time

‘6 34
5;i6 35
t>,i6 19

03

°3

‘3

‘4,

16 28
16 20

°3

16 10
16 14
16 I

°3

03

°3

16 16 6
16 12
16 14

May I

1615 o
9 27 43
9 36

r. afcenlion
obferved.

27 44 39
26 41 43
326 26 35

Declinat.

obferved

Southern.

Off!

8 44 7

10 25 30
10 59 23

6 26 5

326 10 5

23 58 53
23 57 40
23 24 38

10 59 23

11 35 10

16 35

16 33

17 49

35

o

16

0322 2 3021 13 o

0322 2 o

0322 I 45

,22 1

I !

29 2 I

159 51 2o'25 43

10 159 50 42 25 41 43

9 43 51

10 on

lo 43 2

159 50
'59 48

159 46

1625 40 52
58:25 38 26
1225 31 55

'57

3 8 58 7

I 9 8 49 157 25

51^8 44 iiji5‘^ 2

8 53 3o|n-6 I

9 1 oii;6 I

9 38 171156 o

.•) a ‘
28

19 35 41
'9 34 33
' 5 34 9

33 '5 33 42
'8;'5 33 3
30 43

9 50 20156
9 56 19! 156

JO

5'i'55

o

o

59

!0 1 C

4 3' '5
55 '5

?9 19
29
29

9 3'
9 39
9 47

7,' 5 5 30
53,' 55 29
o'55 29

2 (4
47 '4

30 I 3
\

o 9
o o
59 23

7:'o 4 '3455 5

101420155 5

10 21 16:155 5

56 12
3812
23 12

42 28
.j 2 10
42 2

8^10 43 121 54 46

9 -0 35 50454 30

u,;o 50 30153 59

4"
25 10

55! 8

40 37
45 52
34 6

Longitude

obferved.

26 55 33
25 22 56
24 57 36

24 57
24 30 28

^i:;'2o 51 54
20 50 58
19 57 29

'7 38 44

17 37 8
11JJ2 2 28 20
22 27 3

22 26

23 23

22 17 43

103
28 3

'7 9 59
'7 9 31

14 I 28

'4
14 o

'3 58

o 35

33

14

'3 57 58
'3 59 o
'3 57 7

Latitude

obferved r. afcenfion
Northern, fromthe^s.

o / //

4 3 33
2 48 52
2 21 52

I 26 45 —

0 28 53-f

1 16 30 +

2 22 2

1 53 28
Southern.

2 9 33
294

3 8 II

5 56 45

Differ, in

Differ, in
Declin.
from the s(c .

f tf

2 364-
o 43 30 +
26 40 —

I 16 o-f
I 00 +

O 33 15 +

O I o —

0 45-

1 15-
I 30—

5 58 230 23 34-

3*

3'

26 27
25 28

ii 24 52
' 23 7

31 18 2:

651 0
26 49 51
23 42 22

o 15 10 —

O 27 20-f

6 53-

23 42 2

23 41 34

23 39 5'

o 3 56-

o 4 35-
o 43 38-0 6 55-

23 38 39
3 38 28
3 38 21

12 50 9
12 49 46
12 49 19

II 54 12

" 53 49
II 53 29

II 9 24 20 36 16

22 28 12
22 28 6
22 27 41

21 23 48
21 25 40
2^ 25 37

'o 3' 55

'9

9 9 39 '8

5'

1

35

5

25 154
o 24 37 4-|o

o 26 40 —

097 +

o 36 30—
o 37 " +

o 20 414-

o 3.3 7 +
o II 1 1 4-
9 48 4-

*

o

o

22

21

20

New

New

New

20

20

49

3 49^'

24

22

20

ii-f

53 +
7 +

o 42 23 —
o 42 38 —

8 57 +
6 314-

o 14 24-

o I 58 —
o z8 16-p

o 43 JO— !o
o 43 13- jo
054 1 — .0

33

04

45 +
284-

o iS
0 18

:64-
8 +

8

H

o

O

19--

50 —

38-

'7

8 I

9
o

the fame

the fame Com. eft.

^ofvj. Com. eftim.
Comet by azimuths
'. of vj. decl. eftim.

A new Star
the fame
the fame

New

New

the fame.

the fame
tlie fame
7 the fame

New
14 New
1 of Hydra

o 21
o 20
o 20

3 <
55 4
'7-+

o 21 17 +
o 20 594

o '7 53 + )0 20 n

j.

0 0 17—0 12 9 —

' 37 50— |o 15 55 —

'5 37-

o 35'

4^ of Hydra
the fame
the fame

the fame
the fame
the fame

yii 2 New
7 1 2 'the fane
7U2 the fame

f »

7jlo: New
7: lo'rhe fame
7 loahe f.iiTiC

7;i 1 'Now
7; 1 5;New
olioiNew

Coniinuatioa

[ 325 ]

Continuation of the Table of the Pofitions of the Comet.

Tr. Tim.

r. afcenfion

Declinat.

Longitude

Latitude

Differ, in

Differ, in

•V-

. •

obferved.

obferved

obferved.

obferved

r.

afcenfion

Declinat.

■-M

Wh

Southern

Southern.

from the * .

from the:k.

0

0

0

1759-

h f

0

//

0

/

//

0

/

/

0

n

0

//

D

/

//

§

z

May 13

9 24

10

153

53

32

8

3

26

8

51

25

17

35

2

0

4

8-

0

16

3 —

IO

8

New

14

8 57

34

153

47

28

7

32

IQ

8

33

22

17

8

25

0

I

7 +

0

26 36 —

8

6

New

9 45

12

153

47

2

7

30

15

8

32

24

17

6

45

2

21

35 +

0

37 50 +

6

22

of the Sextant

10 16

27

153 46

52

7

30

23

8

32

2

17

6

5'

0

0

30—

0

17 51 +

: 0

7

New

15

9 15

17

153

44

25

7

5

40

8

20

I

16

44

50

2

18 58 +

0

13

15 +

6

22

of the Sextant

II 34

23

153

4-4

10

7

3

17

8

18 56

16

42

42

2

18 43 +

0

10

52 +

6

22

the fame

16

9 54

54

'53

4'

10

6

41

23

8

7

28

16

23

30

2

15 43 +

0

1 1

2 —

6

22

the fame

17

9 20

47

153

39

18

6

22

10

'iX 7 58

14

16

6

21

2

13

51 +

0

30

15-

6

22

of the Sextant

10 37

34

153 38

55

6

20

35

7 56 45

16

4

58

3 50

0 +

0

12

50 +

6

I

A new Star

II 3c

z6

'53

38

40

6

17

22

7

55 49

16

2

0

o

13

15 +

0

26 46-4

7

2

New

18

9 25

51

153

38

25

6

I

0

7

49

13

15

47

2

0

13

0 +

0

10

24 +

- 7

2

the'-Tame

9 48

52

153

38

I r

6

0

21

7 48

51

'5 46

30

3

49

20 +

0

7

24-

6

I

New above

10 57

38

'53

38

5

6

0

c

7 48

30

15 46

13

0

1 2

40 +

0

9 24+

7

2

New above

*9

9 19

30

'53

37

55

5

44

27

7

42

22

15

31

5°

3

49

0 +

0

23

18-

f

I

New above

10 28

31

153

37

4 4

5

43

H

7

41

53

15

S'’

4a

0

12

30 +

0

7

22 —

/

2

New above

2C

8 56

ic

153

38

IC

‘5

28

57

7 36

39

15

17

21

0

12

45 +

0

21

39-

/

2

the fame

9 5

41

153

38

38

>

28

13

7 36

47

15

16

3c>

0

5

30 +

0

15

21 +

8

3

New

9 33

14

'53

38' V

5

27

58

7

39

5°

15

16

13

0

3 48-

0

6

53 +

IC

5

.New

21

9 17

3c

153

39

i8

r

j

14

2

7

32

12

'5

3

18

0

6

lO-f

0

I

10 +

C

3

New abot'e

22

9 34

28

'53

4.0

.. ''

5

I

2

7

28

37

14

50

23

0

7 48 +

0

1 1

50-

3

New

23

9 42

c

153

42

49

• 4 49

a 2

■ 7

25

53

14 38 42

0

9

41 +

0

23

40-

3

the fame

24

9 12

25

153

45

/

4

38

22

7

23

59

14

27

47

0

1 1

59 +

0

34

3c-

0

3

the fame

10 42

4^

'53

45

4'^

4-

37

31

7

24

r 0

14

26

47

0

3

6-h

0

8

56-4

c

.ijiNcw
4! the fame
4|the fame

25

9 26

5?

153

48

4

28

7

22

57

14

17

26

0

5

28 +

0

0

12 —

iC

26

9 33

5‘'

'53

5'

2 I

4

19

33

7

22

46

‘4

8

0

0

8

47 +

0

9

'y .

1C

27

9 29

'5

'53

55

2'

4

1 1

1.2

7

23

29

13 58

44

12

52 +

1

io

17

23-

1C

4

the ftme

28

9 20

c

‘53

559

4

4

3

1 1

7

^3

54

13

49

58

io

1

16

30 +

jo

25

24—

iC

4

the fame

30

lO 12

4;.'

'54

9

>

3

48

‘3

7

52

‘3

32

22

;0

I

30 +

io

"•3

5 —

• C

9

1

New

June 3

10 I

31

'54

26

5^

3

26

n

7

39

22

^3

5

!

21 p.

51

I +

[0

16

8 4

i

1=7

)f the Sextant

XXXIV.,

[ 326 ]

Received December 12, 17^5.

XXXIV. On the Tranjit of Venus in 1769.

To the Right Honourable

The Earl of Morton, Prefident,

To the COUNCIL and FELLOWS
Of the ROYAL SOCIETY,

This Discourse is, with all Humility, inferibed.
By their humble Servant,

Thomas Hornfby.

66^’ obfervations of the late Tranfit

‘ J, of Venus, though made with all
polhble care and accuracy, have not enabled us to
determine with certainty the real quantity of the fun’s
parallax j (ince, by a comparifon of the obfervations
made in feveral parts of the globe, the fun’s parallax
not lefs than nor does it feem to exceed i o".
From the labours of thofe gentlemen, who have
I attempted

[ 327 ]

attempted to deduce this quantity from the theory of
gravity, it fhould feem that the earth performs its
annual revolution round the fun at a greater
diftance than is generally imagined : fince Mr. Pro-
feffor Stewart has determined the fun’s parallax to
be only 6"', 9, and Mr. Mayer, the late celebrated
Profelfor at Gottingen, who hath brought the lunar
tables to a degree of perfedion almoft unexpeded,
is of opinion that it cannot exceed 8"

In this uncertainty, the aftronomers of the prefent
age are peculiarly fortunate in being able fo foon to
have recourfe to another tranfit of Venus in 1769,
when, on account of that planet’s north latitude, a
difference in the total duration may conveniently be
obferved, greater than could poffibly be obtained, or
was even expeded by Dr. Halley, from the laft
tranfit.

The experience which we gained in the year
1761, the knowledge of the errors, from whatever
caufe they may arife, which mufl unavoidably be
committed in obfervations of this kind, will enable
us to put in pradice every method of folving this
problem, and to determine with what degree of ac-
curacy, and within what limits, the true quantity of
the fun’s parallax may be obtained, and confequently
the dimenfions of the whole folar fyflem.

But, before I proceed to give a computation of the
clfed of parallax at the feveral places where this
tranfit ought to be obferved, it will be neceflary to pre-
mife the principles uponwhich the general calculus was

* Mr. Machin, ProfelTor of Aftronomy at Grcfliam College,
deduced the fame quantity many years ago. See a tract entitled.
The Laws of the. Moon's Motion accoreiing to Gravilyy p. 24.

formed.

[ 328 ]

‘formed. Having found, by computing the obferva-
tions made on the tranfit in 1761, that, when the
‘Abbe de la Caille’s folar tables are ufed, the epoch of
the mean motion of Venus for 1761, as given in Dr.
Halley’s tables, requires a corredion of q- 52^7;
and that the place of the afcending node was, at the
beginning of the fame year, in 7!^. 14®. 31^ 10'':
having colleded alfo, by computing the obfervations
of Mr. Horrox in 1639, with the afliftance of Dr.
Halley’s tables of Venus, and the folar tables above-
mentioned, that the motion of the planet’s mean
longitude is 6^. 19°. 12'. 22'', and of the node 52".
18'', in 100 Julian years : I have fuppoied the mean
longitude of Venus, in the beginning of the year
1769, to be 5°. 23'. 48^', and the place of the
node to be in 2^. 14°. 33'. 21'''' — ; and have alTumed
the reft of the planet’s elements as given in Dr. Hal-
ley’s tables. According to thefe numbers, and the
Abbe de la Caille’s folar tables, the ecliptic conjundion.
w'ill happen on June 3d, 1769, at 9''. 59'. 24''
mean time at Greenwich, the planet’s geocentric lati-
tude being lo'. i3''^5 N. The log. of the earth’s
diftance from the fun =5.0065166 ; the log. of
Venus’s diftance from the fun = 4.86 10947 ; and
of the planet’s diftance from the earth 4.4606784;
and the equation of the prtecefiion of the equinodial
points = q- ij" By computing the geocentric
longitude and latitude of the planet three hours be-
fore and three hours after the ecliptic conjundion, I
find the planet’s hourly motion from the fun in the
ecliptic = 3^ 57'', 7 ; the hourly motion in the re-
lative orbit = 4'. o" ^ 3 ; the hourly motion in lati-
tude = o'. 35", 45 ; the angle of the planet’s path

with

[ 329 ]

with the ecliptic 8°. 29'. 02"; the angle of the
ecliptic with the equator ~ 7°. 02h 54^^ and there-
fore the angle made by the planet’s vifible path with
the equator — . 1 5°. 31'. 56'h The geocentric lati-
tude is, as has been obferved, — loh 13''^ 5 : and
hence it is eahly determined that the lead: diftance
of the centers will be loh o6'',8, and the interval
between the time of the ecliptic conjundion and the
middle of the tranfit r= 22'. 21". of time. As the
planet has not yet paiTed its node, the middle of the
tranfit will therefore be at 10''. 2ih 45'^ mean time
at Greenwich. In every inferior conjundion the
motion of Venus is retrograde, and therefore the
effed of the aberration of light in long. — 3'^/,
when reduced to time — 55'h is to accelerate the
feveral phafes of the tranfit ; the equated mean time
of the middle, therefore, will be at io\ 20'. 50'''.
But the place of the planet is alfo affeded by the
aberration of light in latitude; and as Venus’s lati-
tude is decreafing, the lead didance of the centers
will be increafed by 1", 35. The equated lead
didance of the centers, therefore, will be 10'. 08'"',
15. Now, fuppofing the femi-diameter of the fun
15'. 45'',6, and of Venus = 29", the femi-
durations, or intervals between the middle and the
external and internal contads, will be found — 3^.
joh o8'^5, and 2K 51'. 13^', 2. The equation of
time is about 2'. 14^' at the middle of the tranfit, by
which quantity the apparent time is before the mean,
and decreafes at the rate of about 2^'' in 6 hours.
Therefore the apparent times of the feveral phafes of
this tranfit for the meridian of Greenwich are as
follows.

VoL. LV, U u

Fird

C 330 J

App. time.

h

/

//

Firft external contadl, June 3,

7

12

56

Total ingrefs ■ ■■ ■■■ ■■-

“ 7

31

52

Middle

■ 10

23

04

Beginning of egrefs — —

14

16

Laft contadl ■

13

33

1 1

Hitherto we have had no regard to parallax, and
the above times are fuch as would be obferved from
the earth’s center. To the Britifh ifles, and to the
neighbouring parts of the continent, the effedl of
parallax is nearly at a maximum, and will confider-
ably accelerate the times of external contact and in-
grefs. If we fuppofe the fun’s parallax on the day of
thetranfit =8^', 7, the horizontal parallax of Venus
from the fun will be 21", 87; and the times of the
external and internal contadts vifible in England will
be accelerated by the joint clfedts of parallax, both in
the diredtion of the planet’s path and perpendicular
to it j the former by 7'. 09" ; the latter by 7'. 12'^
And therefore Venus will be feen to touch the fun’s
limb at 7^. 5'. 47", more than an hour before the
time of fun-fet ; when the apparent altitude of the
planet above the horizon will be about 8 degrees :
and the total ingrefs will happen at 7*'. 24'. 40''',

when the planet’s altitude will exceed 5 degrees.

If the fun’s parallax fhould be one fecond larger than
we have fuppofed, or 9'', 7, the time of ingrefs will
happen at 7^. 23'. 51".

Thefe times are not here given with any great de-
gree of confidence : but as the errors in the planet’s
orbit will, in June 1769, be nearly the fame with

thofe

C 33* ]

thofe which were obferved 8 years before, it may
be prefumed that the foregoing computation will be
found not to differ very widely from the truth.

Having redtified the globe to the declination of the
fun at the middle of the tranfitr=:22°. 26'. 40", and
alfo at the times of the two internal contads, I find that
the whole tianfit will be vifible to a confiderable part of
Swedifh Lapland, the northernmoff parts of Afia,
and the northern and N. W. parts of North America •
for the circle of illumination at the firff internal con-
tad pafTes along the weftern coaft of Africa from
Cape Verd through the Straits of Gibraltar to Cler-
mont in France, leaving Paris about a degree and a
half to the Weft j from thence it pafies throuo^h
Germany and along the Baltic Gulf, through Wi-
bourg and Archangel, along the northern coaft of
Afia i and then traverfing the N. E. parts of Siberia,
it pafies over Japan, enters the great Atlantic ocean,
leaves the Marian ifles and New Zealand on the
Weft, and running round Cape Horn, and near
Falkland ifle, pafies on to Cape Verd through the
Ethiopic ocean, in a diredion nearly parallel to the
eaftern coaft of South America. Ail places fituated
under the firft part of this line from Nova Zembla
towards Cape Horn will fee Venus enter upon the
fun at the time of fun-fetting, and at fun-rifing un-
der the other half of it. — The circle of illumination
at the beginning of egrefs enters Europe to the North
of Drontheim in Norway, and crofiing the Bothnic
and Finland gulfs, pafies over Mufcovy and the
Cafpian fea j and running through Perfia traverfes the
Arabian gulf, going fouthward near the ifles of Mal-
divia, and taking a large circuit towards the South

U u 2 Pole,

[ 332 ]

Pole, returns through Mexico, Loulllana, Canada,
and the fouthern parts of Greenland, to Drontheirn.
So that almoft all Africa is deprived of a view of this
tranfit, and a very confiderable part of Europe.

If we examine the obfervations of the tranfit in
1761, in places where there were more obfervers
than one, and where the contafls were obferved when
the fun was near the horizon, and at higher altitudes,
we may fafely conclude that the obfervations will
be made with fufficient accuracy when the fun is at
fuch altitudes above the horizon, as not to be greatly
affeded by the vapours. At the Obfervatory at Upfal,
when the fun’s altitude at the ingrefs was 34. degrees,
three obfervers differed 22", whereas at the egrefs,
when the fun was 44°-4 high, the difference amounted
only to (>" , It fhould feem, therefore, that obfervers
ought not to be fent to places where the fun will be
much lefs than 5° high at the time of either of the
contads.

It appears by computation, that the joint effcd of
the parallaxes both in longitude and latitude to
lengthen the total duration, will be the greatefl; to
thofe places which are about 24° or 2 5° to the Eaft
of Greenwich in the 66th or 67th degree of N. lati-
tude, when the fun’s altitude is about 5° at each con-
tad, or if the fun’s altitude at each contad be re-
quired = 10°, the latitude of places under the fame
meridian mufl; be 73° or 74* N. In the former cafe,
this tranfit may be very advantageoufly obferved at
Tornea°, Kittis, and the adjoining parts of Swedifh
Lapland} in the latter, at Wardhus, and in the neigh-
bourhood of the North Cape : for an error of one or
two degrees either in longitude or latitude will make

[ 333 ]

but a very Inconliderable difference in the paralladtic
time ; as will fufficiently appear from an infpedtion
of the following Table, which contains the joint ef-
fect of the parallaxes of longitude and latitude in
accelerating the times of the two internal contadfs at
Tornea°, Kittis, and Wardhus, for each of which
places the paralladfic angle, or the angle made by a
vertical circle with the orbit of Venus, was carefully
computed.

Firft

Second

Total

Total

Difterenci

intern.

intern.

effcdl of

effedl of

for i'' ol

contadl

contadl

|j

00

par.= 9",7

parallax.

/ /

, . 1

/ //

Tornea°

6 53

4 47

4- I I 40

4-12 58

1 IS

Kittis

6 51

4 43

4- 1 1 34

+ 12 51

I 17

Wardhus

6 38

4 41

4-11 19

+ 12 37

I 18

Having determined the gveated: effedl of parallax
in lengthening the total duration at fuch places to
which obfervers may conveniently be fent, let us ex-
amine how far we may be enabled to obtain obferva-
tions in fuch parts of the earth’s furface where the
effedl of parallax will be contrary j and confequently
where the total duration will be as flaort as poffible.
By the affiftance of calculation it may be found, that
in the latitude of about 54° South, and in 155° of
Weft longitude nearly, the total duration will be the
fhorteft, when the fun’s altitude is 5° j or in about
47° of South latitude under the fame meridian, when
the fun is 10° high. And accordingly, by computing
the paralladllc angle for the latitude of 55° South,
and the meridian oppofite to that of Tornea'’, I find

[ 334 ]

tliat the total duration will be fhortened by parallax
no lefs than \t! 53'', fuppofing the fun’s parallax

8'^, 7. and confequently that there might be ob-
ferved a difference in the total duration between this
place and Tornea° of 24' 33^^^: a difference confider-
ably greater than was expected by Dr. Halley in
1761 ; and, fuppofing with that affronomer, that
the obfervations at each contact may be taken true to
a fingle fecond, (which indeed experience will not
warrant) fufficient to determine the fun’s parallax
within -7-4-5-*'’ part of the whole.

But as this and the other point fall in the great
South fea, where it does not certainly appear that
there is any land, let us enquire in what parts of the
South fea we may reafonably expedl to find land.
From the accounts of forne of the circumnavigators,
it fhould feem that there are iflands fcattered here
and there about the tropic of Capricorn, particularly
the ifland or iflands of St. Peter, in about 150° of
W. longitude from Greenwich, and in about 21° of
S. latitude. I have therefore computed the paralladtic
angle for a place 10'’ 22' 50'' to the Weft of Green-
wich, and in 21° of S. lat. and find that the ingrefs
will happen 6' 10'' later, and the beginning of egrefs
6' 6" fooner, than if feen without parallax ; that
the total duration is' therefore ftiortened 12' W' by
parallax ; and confequently that there is a difference
of 23' 56'' in the total duration between Tornea°
and this ifland, fuppofing the fun’s parallax —8^', 7 on
the day of the tranfit ; or of 26' 39'', if that parallax
be fuppofed —

About the latter end of the 16th century, Don
Pedro Fernandez de Quiros made two voyages for

the

C 33S ]

difcovery of the fouthern continent and iflands, under
the patronage of the Viceroy of Peru. From feveral
memorials which he prefented to the court of Spain in
the year 1609, with a view to procure a fettlement of the
countries he had actually difcovered, it appears that he
had found many iflands, and particularly a large tracfl
of land lying in or near the 15* of S. latitude, well
peopled and well cultivated, the inhabitants generally of
a peaceable difpofition. The produce of this country
is reprefented to be fuch as to render it a fit objedl to
any commercial nation j confifling of gold, filver, pearl,
fpices of many forts, and fu gar- canes. He defcribes
feveral fafe and commodious harbours, particularly
Puerto de la Vera Cruz in lat. 15° 40' S. capable of
holding 1000 fhips, with a fafe anchorage in every
partj and where he himfelf adtually ftaid thirty-fix
days with three fhips. From the wholfomenefs' of
the air, the fertility of the foil, and many other cir-
cumftances peculiar to this continent, he makes no
fcruple to prefer it to every country which the Spa-
niards had conquered whether in the E. or W. In-
dies — I muff, however, obferve, that, if this country
be 195° to the W. of London, the whole of the tranfit,
in all probability, will not be vifible; as Venus will
enter wholly upon the fun’s difk at, dr a few minutes
before, the'time of fun-rifing.

The Spaniards gave the name of the Iflands of
Solomon -to certain countries in the South feas, re-
ported to be very rich in gold. They were firfl; dif-
covered* by Alvarez de-Mendoza in 15275 ^n^d are fup-
pofed by fome to be the very lands which were after-
wards found by Fernandez de Qqiros. The Spaniards
* Harris’s Voyages, 2d Edit. Vol. I. p. 63.

are

[ 336 ]

are faid to have had very clear and fatisfadlory accounts
of thefe iflands; but to have deftroyed them for po-
litical reafons, by exprefs orders from Old Spain,
when Sir Francis Drake failed into the South feas
Their fituation is not known ; and from fome fruit-
lefs attempts to find them, it has been, and is ftill,
perhaps, queflioned whether there be any fuch
iflands. — Some time after the year 1720, while
Capt. Betagh, Commander of the Marines on board
of Capt. Shelvocke’s fliip, was in Peru, the difcovery
of thefe iflands was again attempted, upon fome frefli
information, by command of the Viceroy -f- j but
without fuccefs : for the latitude of thefe iflands is not
even nearly known. They are, however, fuppofed
to lie between the loth and 20th degree of S. latitude,
in about 175° of W. longitude from London, accord-
ing to the befl: Englifli and French maps : or, accord-
ing to fome geographers, thefe iflands are only 120®
to the VV^. of London.

Soon after the government of the Dutch in the
Eafl: Indies was fettled at Batavia, it was thought
proper by the Dutch Eaft-lndia company that
an exadt furvey of their countries already difco-
vered fliould be made and preferved. For this
purpofe Capt. Abel Janfen Taiinan failed from Ba-
tavia in 1642. In this voyage feveral lands were
difcovered, particularly the two iflands of Amfterdam
and Rotterdam, lying in 2 1"" and 20° of S. latitude
and in 173° or 174° of W. Longitude. The ifland-
ers are reprefented to be of a civil and peaceable dif-

* Harris’s Voyages, 2d Edit. Vol.I. p« 63.

t Id. ib. p, 245.

pofition.

[ 337 ]

portion, and to all appearance unacquainted with the
ufe of arms; the lands well cultivated, and planted
with air kinds of fruit-trees —Not far from thefe
two iflands are nineteen or twenty more, in 17° or
18“ of S. latitude, and 4° or f to the W. of the/or-
naer.

Mr. de Chabert, in the Memoirs of the Academy
of Sciences for 1757 •f') has given an account of four
iflands in the South fea, lying in about 10° of S. la-
titude, and 134° or 135'' to the Weft of London,
difcovered in July 1595,' by Alvaro Bendano de
Neyra, commander of a Spanifli fquadron of four
Blips, in his fecond voyage, for the difcovery of the
Solomon-ifles.

“ The firft and eafternmoft he named the Ifland
“ of Magdalene. -It .is .about fix leagues in circuit,
with high coafts and mountains. iii tli^ middle; and
“ is extremely well peopled. More -than forty In-
dians came on board. the ftiip.

“ To the N. W. at the diftance of about ten
« leagues, lies the ifland of St. Peter, near three
“ leagues in circuit, and prefenting air agreeable
“ profpedl to the eye. '

“ About five leagues to the S. W. of St. Peter is
“ another and larger ifland, named Dominica, about
“ fifteen leagues in circumftrejice, well peopled, and
affording beautiful profpeds.. - ^

“ To the South of this ifland is St.Chriftine, near
‘‘ eiaht leao-ues in circumference. 1...

o o ■

n.
1; ) V 1

* Harris’s Voyages, 2d Edit. .Vol. b p. 327. 3,
f Ivdcmoiresde rx^^cademie ds5 Sdeuces pour I737> >P’ S®»

- ... ; -Jiiui 1

VoL. LV. X X “ The

C 338 ]

“ The whole fquadron pafTed between this ifland
“ and Dominica, and anchored in a very good ha-
“ ven, to the Weft of St. Chriftine, in the latitude
of 9° 30'; near which they found a rivulet of
“ very fine and frefh water. The coafts of all the
“ iflands feemed in general very fafe and commodi-
ous for ftiipping.

“ In this harbour they found all kinds of re-
frefhment j as fowls, hogs, fugar-canes, plan-
“ tanes, cocoa nuts, and many forts of other fruits.

“ They converfed with the natives of the country,
“ and eredted three erodes.”

Beddes the countries already mentioned, it ft.ould
feem from Mr. de Lille’s map of the fouthern he^
mifphere, that there are many iflands fltuated be-
tween the parallels of 5® and 23® of South latitude
in the great Pacific Ocean ; the moft remarkable of
which, together with thofe already mentioned, are
given in the following T able.

Ifland of St. Peter, according to fome maps — —

Illands of Mendoza ■■ — -

Iflands difeovered by Quiros, i6cj

Ifles des Tiburons, or Dog Ifland — —

Ifle Habitee

Iflands of St. Barnard - > — -

Water Ifland •' ■ — - ■ ■ .

Fly Jfland — .■■■■. ■ — —

Land difeovered by Mendana •• — - — — ■

Ifle de la Belle Nation — — —

Jfland of Jefas - — - . —

Rotterdam I. — - ~

Amfterdam 1. - — - — — — — —

Solomon Jfles — — —

Ifland of Taumaco ■ i

Prince William Iflands ■ — ■ ' . <

Ttrra Auflralis

w.

s.

Lon.

Lat.

130

18

'35

9r

'38

2 1

.41

16

144

‘7

150

1 1

>5'

'53

‘5v

157

4

160

1 2

162

7

•73

2o{

‘74

21

‘75

JO

‘77

‘3

‘78

‘7 •

»yo

*S

It

[ 339 ]

It appears, I think, not only poffible, but highly
probable, that obfervers may be Rationed in the South
feas. I have, therefore, computed the paralladtic
angle for different longitudes and latitudes, anfwering
to fuch places whofe pofitions feem to be mofl cer-
tainly known ; the refult of which calculations is
given at one view in the following Table.

W.long.

S. lat.

Places Names,

Firft

intern.

contaft

Second

intern.

contaft

u Owoo
11

Difference in
tot.dur. from
Torneao.

155 42
133 0

>73 0

190 0

zt 0

9 3°
ZO 30

0

[(land of St. Peter
Mendoza Illes
Amfterdamand Rotterd. I.
Terra Auflralis

6 10

4 3>
6 19

5 43

6 06
6 49

4 42
3 >6

12 16

H 20
1 I 01
8

' It

23 S®
aj «o
22 4t
20 39

By the laft column it appears, that if an obfcrver
be Rationed in any of the above places, perhaps in
any part of the South feas where the whole tranfit is
vifible, and the total duration obferved there be com-r
pared with that at Tornea®, we may obtain a differ-
ence in time from 20 to 24 minutes j which is in-
deed fo confiderable, that the fun's true diftance mufl
be afcertained more exadly than can poffibly be ex-
pected from any other method.

But, if it fhould be found impracticable to ftation
an obferver in the South feas, the lofs may in a great
meafure be repaired, if the tranfit be obferved in fuch
parts of North America where the whole is vifible.
At Mexico the total ingrefs will happen when the
fun is very near the meridian j and, if the longitude
of the place and the general computation may be de-
pended upon, the beginning of egrefs will happen
towards the time of fun-fet, when the apparent alti-
tude of the fun will not much exceed four degrees.

X X 2 Obfervers

[ 340 ]

Obfervers therefore fhould be flatloned farther to the
Weft about Cape Corientes j at which place and at
Mexico, though in about 20° of N. latitude, the ef-
fedt of parallax will ftill be conftderable, particularly
at the egrefs, as appears from the following Table.

Places^

in-
ternal con-
taft.

Second

internal

contaft.

Total ef-
feft of par,
= 8",7-

Difiercnce in
tot. dur. from
Tornea®,

Mexico

/ //

/ //

/ //

// //

I cy

5 03

6 10

^7 50

Cape Corientes

0 26

5 00

5 26

17 06

By comparing the obfervations to be made at either
of the above places, or in any of the neighbouring
parts, with thofe of Tornea°, a difference of more
than feventeen minutes in the total duration may
commodioufly be obtained j by which the quantity
of the fun’s parallax may be determined agreeably to
the method propofed by Dr. Halley in the cafe of
the laft tranftt, and in which no error but that of the
obfervatibn cap take place, fuppofing the fituation of
the two places to be nearly known.

When D’r, Halley’s computation was examined,
and it was found that fo great a difference in the to-
tal duration of the tranfit at any two places as had
been expetfed could not conveniently be obtained ;
another method was propofed, and was accordingly
carried into execution, viz. to ftation two obfervers
in fuch a manner that one of the internal contadts
might be obferved with the greateft difference poftible
arifing from a contrary effedt of parallax at the two
places. This method, though neceffarily inadequate,

becaulc

[ 341 ]

becaufe the longitude of the two ftations muft be ri-

goroufly known, may be pradtifed at both contacts
in 1769.

It appears by computation that the time of the firft
internal contact in the evening is accelerated as much
as poffible by parallax in 48° 42' of N. latitude, and
6 to the Eaft of Greenwich, at or near Nancy in
France. But this computation is framed upon a
fuppofition that the fun’s center is in the very horizon :
in which circumftances no obfervation can be taken.

If the fun’s altitude at the time of the contadt fhould
be required equal to 5 or 10 degrees, then it will
appear that Greenwich and Dublin are ftations very
advantageous ; and we have already feen that the
time of ingrefs at the former place will happen 7' \ l"
fooner than if feen from the earth’s center, on
account of parallax. Indeed the effedl of parallax *
will be nearly the fame to every part of Great Bri-
tain. The part of the earth’s furface, where the effedl
of parallax' upon the planet at the fame contad will
be as great as poffible in a contrary diredtion, when
the fun’s altitude is about 5°, is in 46° of S. latitude
nearly, and in 168° or 169° of W. longitude from
London, in the great Pacific Ocean, where it does
not at prefent appear that there is any land. If, how-
ever, an obferver fliould be Rationed in any of the
iflahds in the South fea, for which a computation has
already been made, even in the iflands of Mendoza,
the morning ingrefs will be found to be retarded by
parallax 4'' 3 j and confequently a difference at this
contadt of 11' 43^'' may be obtained by comparing
the obfervation of the hrfl internal contadt with the
obfervations at Greenwich ; or i F 24'', if the fame
obfervation be compared with that at Tornca°.

5

In

[ 3+2 ]

In order to fee the beginning of egrefs accelerated
by the greateft effedt of parallax poffible, when the
altitude of the fun is 5°, an obferver mud: be ftationed
in about 123'" of Weft longitude from London, and
in about 19° of S. latitude; or, as it does not appear
at prefent that there is land there, the obferver may
be ftationed with confiderable advantage either in the
iflands of Mendoza, or in the ifland of St. Peter. The
fame contact will be as much retarded on account of
parallax to an obferver placed under the tropic of
Cancer, in about 67° of E. longitude from London.
Th is point indeed falls into the Gulf of Sindi j but as
a difference of many degrees, either in longitude or
latitude, will occafion but a very inconfiderable dif-
ference in parallacftic time, this contact may be very
advantageoufly obferved on any part of the coalt
from the mouth of the Indus to Cape Comorin,
and from thence along the coaft of Coromandel and
Golconda as far as the mouth of the Ganges. It
may naturally be expedted thk the end of the tranfit
will, if the weather be favourable, be obferved at
many of our own fettlements in thefe parts : I have
therefore computed the effedl of parallax at the egrels
for Madrafs and Calcutta, at which places the laft
tranftt was obferved ; and find that the time of the
fecond internal contadt will happen 6' 41" later on
account of parallax at the former, and 6' 44 ' at the
latter, than if feen from the earth’s center. By com-
paring the obfervations made at either of the above
places with the correfponding obfervation at Mexico,
we may obtain a difference of 1 1' 44^' ; a difference
greater than could be obtained by any obfervations
that could conveniently be made at the egrefs in the
tranfit of 1761.

Upon

[ 34-3 ]

Upon the whole, the neceffity of fending an obferver
into the South feas fufficlently appears, whether it be
propofed to determine the fun’s parallax by the dif-
ference in tho total duration of the tranht, or by the
obfervations of the internal contadts either at the in-
grefs or egrefs. For if there fhould happen to be no
land in the meridian oppohte to Tornea° and in about
21° of S. latitude j yet if an obferver can be Rationed
either in the iflands of Mendoza, or in the iflands of
Amflerdam and Rotterdam, a difference in paralladtic
time will be obtained as in the following Table.

Places compared^

Diiierencc
in total
duration.

Difference
at ingrefs.

Differcucc
at egrefs.

.Tornea® and Mendoza Ifles
Tornea® and Amflerdam orRotterdam
Tornea® & the opp. merid. in 2 1 S. lat.

/ "

23 00

22 41

23 56

/ "

11 24
13 12
13 03-

II

9 29
10 ^3'

If the flcy ffould prove favourable, the obfervations
made at Tornea° and in any of the above places will
enable us to determine the fun’s parallax with great
precifion,and independent of the exadl knowledge of
the longitude of either place. But as the iituation of
Tornea° is perhaps very exadtly known, if it fhould
be convenient to the louthern obferver to continue
long enough upon his ff ation to determine the exadt
longitude of it, to which the fituation of Jupiter at
that time will greatly contribute, both methods might
be pradlifed at the fame time, and they would mu-
tually confirm and illuftrate each other.

An opportunity of obferving another tranfit of
Venus will not again offer itfelf till the year JH74.
It behoves us therefore to profit as much as poffible

by .

[ 344 ]

by the favourable fituatlon of Venus in 1769, when
,we may be alfnred the feveral Powers of Europe will
again contend which of them (hall be mod: inflru-
mcntal in contributing to the folution of this grand
problem. Poflerity mud: refled: with infinite regret
upon their negligence or remiflhefs ; becaufc the lofs
cannot be repaired by the united eftorts of indullry,
genius, or power. Plow far it may be an objed of
attention to a commercial nation to make a fettlement
■in the great Pacific Ocean, or to fend out fome diips
of farce with the glorious and honourable, view, of
difeovering lands towards the South pole, is not my
bufinefs to enquire. Such enterprizes, if fpeedily
undertaken, might fortunately give an advantageous
pofition to the adronomer, and add a ludre to this
nation, already fo eminently didinguiflicd both in arts
and arms.

I

Oxford, December i, 1765.

i

• INDEX.

A N

INDEX

TO THE

Fifty.Fifth VOLUME

OF THE

Philofophical T^ranfaEiions.

For the Year 1765.

A.

/JIR, various obfervanons concerning it, page 149.

182, &c. does not become lefs elaftic by paffing
through the lungs of an animal, 173.

Alcyonium^ fee Sponges.

JJlronomical obfervations, made at Vienna by Father
Jofeph Liefganig, p. 130,

Aimofphere^ feveral Phenomena of it accounted for,

p. 1 60.

B.

Balance^ of a new conftrudion, for weighing, propofed,

y y ■ Bara-

p. 205.

VoL. LV.

INDEX.-

Barcmete}\ a portable one defcribed, p. 83.

Bevis^ Dr. John, his letter containing agronomical ob-
fervations made at Vienna, p. 150.

Bloody human, microfcopical obfervations on it, p. 252.

Brownrigg^ Dr. his experimental enquiry into the mi-
neral elaftic fpirit, or air, contained in Spa water,
p. 218.

C.

Colehrook^ Mr. Jofiah, his account of the fequel of the
cafe of Ann James, who had taken the green hemlock,
p. 271.

Colours^ the different ones, in natural bodies, arife from
the different denfity of their component particles, p. ii.
Experiments on the feveral metallic bodies, what colour
each produces when feparated from their fulphur, and
melted and united with glafs, 13. Of their colour
under other preparations, 28. Conjedure about the
caufe of the green colour of vegetables, 36.

Cornet^ (the famous one of 1682) its return predided by
Dr. Halley at the end of 1758, or beginning of next
year, p. 295. Reafons of the difficulty in afcertainino-
the time precifely, ibid. Endeavours of Mr. Clairaut
on this fubjed, 296. Obfervations on the feveral ap-
pearances of this comet, from January 21, to June 3,
1759, and on its comparative pofition to other ftars,
298, &c.

Copper, its colour when mixed with glafs, 8cc. p. 20,

32. ^

Cork, Experiments of its fpecifiick buoyancy in different
waters, p. 95. Of the quantity neceffary to fuftain a
man in the water, p. 103.

D.

Decreafe of Heat, in proportion to the height of fitu-
ation, p. 126.

Delaval,

INDEX.

Delaval^ Edward, efquire, his experiments and obfer-
vations on the agreement between the fpecific gravities
of the feveral metals, and their colours when united to
glafs, p. lo.

Dollond^ Mr. Peter, ^QQTelef copes.

E.

Earth-quake^ that at Lifbon, December 26, 1764, p. 43.
A method to know the ftrength and diredion of it, 44.

Edwards, Mr. his defeription of a beautiful Chinefe
pheafant, p. 88.

Ellis, John, efquire, his letter on the nature and for-
mation of fponges, p. 280.

Ergot, fee Rye.

Evaporation, Differtation on the nature of it, p. 146.
Performed by folution, 149. This principle accounts
for feveral phasnomena of the atmofphere, 1 60. Of
refpiration, 172. Of fire, 174.

Exhalations, the knowledge of them applied to mineral
waters, p. 236.

F.

Fergufon, James, his methods to find the quantity of
tim.e, in any given number of mean lunations ; the
number of troy pounds in any given number of avoir-
dupoife pounds, &c. p. 61.

Fire, how fed by air, p. 1 74.

Franklin, Benjamin, L L. D. his phyfical and meteoro^
logical obfervations, chiefly concerning air, p. 182.

G.

Gale, Dr. Benjamin, his memoirs concerning the pradice
of inoculation for the fmal 1-pox, in the BritilE Ameri-
can provinces, p. 193. His letter concerning the fuc-
cefsful application of fait to wounds made by the biting
of rattle-fnakes, p. 244.

y y 2

Cold,

index.

Gold, its colour when mixed with glafs, &c. p. 28.

Griffith, Mr. of Pembroke College, Oxford, his account
of the effcdts of a (form of thunder and lightning there,
P- 273*

H.

Hadley s quadrant recommended for furveying harbours,
and in fome cafes of pilotage, p. 70.

Halley, Dr. his remarks about fixing the return of fome
comets, p, 295. Concerning the ufe of parallaxes in
obferving the tranfics of planets, p. 340.

Hamilton, Hugh, D. D. his diflertation on the nature of
evaporation, &c. p. 146.

Heat, in what proportion decreafed by the height of
fituation, p. 126.

Heberden, Dr. William, his account of a fait found at the
Pic of TenerifFe, p. 57. Of a ftone voided without
help from the bladder of a woman at Bury, 128.

Heberden, Dr. Thomas, his obfervations for fettling the
proportion, which the decreafe of heat bears to the
height of fituation, p. 126.

Hemlock, green, fequel of the cafe of a perfon who had
taken it, p. 271.

Hope, Dr. John, his letter concerning the rhubarb root
raifed in Scotland, p. 290.

Hornjhy, Rev. Mr. his account of the tranfit of Venus,
1769, p. 326.

Humber, pilotage of the mouth of it, how might be aflifl-
ed, p. 74* .

Hydrophobia, cafe of a fuppofed one, falfly faid to be
cured by vinegar, p. 139.

I.

Jaw locked, fuch a cafe, p. 85. Owing to a wound in
the foot, 86. Obfervations on the nervous fyftem,
87.

Inoculation,

INDEX.

Inoculation for the fmall-pox, hiftorical memoirs of the
pradlice in the American provinces, p. 193.

Iron^ its colour when mixed with glafs, &c. 22, 32. Its
effefl on growing vegetables, p. 36.

L.

Lavingtony Dr. of Taviftock, Devon, his account of a
lady, who drank fea-water for an inflammation in her
upper lip, p. 6.

heady its colour when mixed with glafs, &c. p. 17, 30.

Liefganigy Father Jofeph, his agronomical obfervations
made at Vienna, p. 136.

lAghteningy fee hhunder.

Lijhony Earthquake there, December 26, 1764, p. 43.

Ludlamy William, his account of a balance of a new con-
ftrudion, fuppofed to be of ufe in the woollen manu^
fadture, p. 205.

LunationSy a method for finding the quantity of time con-
tained in any given number of mean lunations, and
vice verfay p. 61.

LungSy cafe of an extraneous body forced into them, p, 39.
Relief by the breaking of an impofthume, 41. One
lobe of them found wanting in a young woman, 79.
Reflexions thereon, 8 1 . Refpiration ftill carried on, 82.

M.

Mejfier, Mr. his m.emoir concerning the return of the fa-
mous comet of 1682, p, 294.

MicrofeopeSy new, made at Naples, defer ibed, p. 246.

Mildew y in corn, what it is, p. 108.

Michely Reverend Mr. his recommendation of Fladley’s
quadrant for furveying harbours, p. 70.

Mineral WaterSy their elaftic fpirit confidered, p. 236.
fee Spa. Ufes,of a knowledge of mineral exhalations,
when applied to difeover the properties of mineral wa-
ters, p. 236.

Mifisy how formed, p. 163.

MortoHy Earl of, his account of the cafe of a fuppofed
hydrophobia, p. 139.

Negro,

INDEX.

N.

4

Negroy white, fhewn before the Royal Society, an account
ofhim, p. 45. His parents black, 46. More inftances of
fuch deviation in colour, 47. Wafer’s account of white
people on the Ifthmus of America, 50.

Nervous fome reflexions on it, p. 87.

Newton, Sir Ifaac, his obfervation concerning the caufe of
colours in natural bodies, p. 10,

P.

Paitoni, John Baptifl:, phyfician at Venice, communicates
an uncommon anatomical obfervation, p. 79.

Parfons, Dr. his account of the Pholas Conoi'des, p. i.
Of the white negro fhewn before the Royal Society,

P* 45*

Pheafant, a beautiful Chinefe one deferibed, p. 88.

Phelas Conoides, or wood-mufcle, a defeription of it, p. 2.
Its lodgment in the wood, p. 3.

Plants, of their fexes, p. 258. Catalogue of the fifty
from Chelfea garden, prefented to the Royal Society, for
the year 1764, p. 91. fee Vegetables.

^adrant, Hadley’s, recommended, p. 70. A particular
application of it in fome cafes of pilotage, propofed
and illuftrated, p. 71.

R.

Rain, how produced, p. 163.

Rattle- fnakes, their bite cured by fait, p. 244.

Refpiration, fome reflexions on it, p. 172.

Rhubarb, the true fort, defeription of fome plants of it
raifed in Britain, p. 290.

Rye, of a falfe or vitiated kind, a difeafe from the eating
of it deferibed, p. io8. Method of cure, p. 123.

Salt,

INDEX.

S.

Salt^ a fort of it found on the Pic of Teneriffe, p. 57.
It appears to be the nitrum of the ancients, or the folhl
alkali, 58. Difference between that and vegetable
alkali, 59. Salt applied to the bite of a raule-fnake, 244.

SeaW ater, cafe of a young lady who had drupk it with no
good effed, p, 6. Queries concerning the ufeofic,
efpecially by thin, tender, and hedlical conftitutions, 8.

Short, Mr James, communicates to Dr. Birch Mr. Dollond’s
letters, p. 54.

Silver, its colour when mixed with glafs, &c. p. 18, 31.

Snow and Hail, how produced, p. 163.

Solution obfervations thereon, p. 153.

South-Sea, what land already difcovered there, and proba-
bility of more, p. 334.

Spa-Water, experimental enquiry into the mineral fpirit
contained therein, p. 218. *

Sponges, of their nature and formation, p. 280. The
worms found in them, not their fabricators, but inhabi-
tants, 281. They have an animal aftion, or fy ftole
and diaftole, 284. Approach to the Alcyonium, 285.

Spry, Dr. of Totnefs, his improvements of a portable baro-
meter, p. 83.

Stars, their right afcenfions and declinations, p. 321.

Styles, Sir John Eyles, his account of fome new microfcopes
made at Naples, p. 246. His Letter concerning the
fexes of plants, 258.

Stone, account of one voided without help from a woman’s
bladder, p. 128.

T.

’Telefcopes, an improvement in the objed-glaffes of them,
by Mr. Peter Dollond, p. 55.

'Theorems, two, by Edward Waring, M. A. Lucafian pro-
felfor of mathematics at Cambridge, p. 143.

Thunder and Lightening, account of the effedfs of it in
Pembroke College, Oxford, June 3, 1765, p. 273.

Tijfot, his letter to Dr. Baker, concerning difeafes which
arife from ill-afiedled rye, p. 108.

4

Vegetables,

INDEX.

V.

Vegttahles,\\\t\x colour whence, p. 36. Their impregna-
tion, remarks thereupon, and a defcription of the pollen,
feed-veffels, &c. of feveral claffes, &c. p. 261.

VenuSy the tranfic of that planet which will be in 1769,
propofals for the more advantageous obferving of it,
p. 326. Effedt of parallaxes, 332. At what places
the obfervation might beft be made, 333.

Vienna, aftronomical obfervations made there, p. 130.

Waring, Profeflbr, two theorems of his, p. 143. .
Water, the quantity and weight of it in a cylindrical pipe
of any given diameter, afeertained, p. 68. How eva-
porated, 146. Boiling water, the bubbles on it
whence, 175.

Weight, troy, reduced to avoirdupoife, and vice 'verfa,

p. 66. . ■ ‘

Wilkinfon, Dr. his courfe of experiments to afeertain the
fpccific buoyancy -of cork in different waters, p. P5.
Wood-Mufde, I'ee Pholas Condides. • ^

Woolcombe, Mr. furgeon at Plymouth Dock, his cafe of a
locked jaw, p. 85.

W.

The End of the Fifty-fifth Volume-

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