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TRANSACTIONS,
ROYAL SOCIETY
ino N D ON,
VOL. LXXIV. For the Year 1784.
PAR FOL
Lon Dp ON,
SOLD BY LOCKYER DAVIS, AND PETER ELMSLY;:
PRINTERS TO THE ROYAL SOCIETY.
MDCCLEXXIV,
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A OVE Ro 1 SRM oR ON a
ETE Committee appointed by the Royal Society to dire& the pub-
lication of the Philofophical Tranfadtious, 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 former Tran/actions, that the printing of them was
always, from time to time, the-fingle act of the refpective Secretaries, till
the Forty-feventh Volume: the Society, as.a body, never interefting them-
felves any further intheir-publication, than by occafionally recommending
the revival of them to fome of their Secretaries, when, from the particular
circumftances- of their affairs, the Tranfactions had happened for any
leneth 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 knowledge, and benefit of
mankind, the great ends of their firft inftitution by the Rdyal Charters,
and which they have ever fince fteadily purfued.
But the Society being of late years greatly inlarged, and their com-
munications more numerous, it was thought advifable, that a Committee
ef their members fhould be appointed to reconfider the papers read be--
fore them, and feleé out of them fuch, as they fhould judge moft ‘pro-
per for publication in-the future Lranfactions ; which was accordingly
done upon the 26th of March 1752. And the grounds of their choice -
are, and will continue to be, the importance and fingularity of the fub--
jects, or the advantageous manner-of treating them; without pretending
to anfwer for the certainty of the facts, or propriety of the reafonings,
contained in the feveral papers fo publifhed, which muft {till reft on the.
eredit or judement of their refpective authors.
A.2. le:
Cag
Tt is likewife neceflary on this:occafion ‘to remark, that it is an-efta-
blifhed rule of the Society, to which they-will always adhere, never to
give their opinion, as a body, upon any fubjeé, either of Nature-or Art,
that comes before ‘them. And therefore the thanks, which are -fre-
quently propofed from the:chair, to be given to the authors of fuch pa-
pers, as are.read at their accuftomed meetings, or to the perfons through
whofe hands'they receive them, are to be confidered in no other light
‘than as a matter of civility, in return for the refpeét fhewn:to the Society
‘by thofe communications. The like alfo is to be faid with regard to
‘the feveral projects, inventions, and curiofities of -various‘kinds, which
are often exhibited to the Society.; the authors whereof, or thefe whe
exhibit'them, ‘frequently take the liberty to report, and even tocertify
‘in the public news-papers, that they have met with the higheft applaufe
and approbation. -And therefore it 1s hoped, that no regard will here-
-after be paid. to fuch reports, and public notices ; which in fome inflances
have been too lightly.credited,.to thedifhonour of the Society.
a
OO N FT EN gS
OF
VOL. LAXTY. Page 1
I AN Objervation of the Variation of Light in the Star Algol.
In a Letter from Sir Henry C. Englefield, Bart. F. R. 8.
and S. A. to Jofeph Planta, E/g. Sec. R. S, page I
II. Obfervations on the Obfcuration of the Star Algol, dy Palitch,
a Harmer. Communicated in a Letter from the Count de
Bruhl, F. R. S. to Sir Jofeph Banks, Bart. P.R.S. p 4.
Ill. Further Objfervations upon Algol. By the fame. p. 5
IV. Defcriptions of the King’s Wells at Sheernefs, Languard-
Fort, and Harwich. By Sir Thomas Hyde Page, Kut.
F.R.S.3 communicated by Lieut. Gen. Rainsford, F. R. S.
p- 6
V. Extradé of a Letter from Edward Pigott, Ej. to M. de
Magellan, PF. R. S.3 containing the Difcovery of a Comet.
( Pej2°
VI,
vi CHO. Nigh Ey Ne ans: ,
VI. Project for a new Divifion of the Quadrant, By Charles.
~ Hutton, LL.D. F.R.S. In a Letter to the Rev. Dr.
Mafkelyne, FR. Sv and Aftronomer Royal. p: 2t
VIL. On the Means of difcovering the Diftance, Magnitud>, &c..
of the Fixed Stars, m confequence of the Diminution of the
_ Velocity of their Light,-in cafe fuch a Diminution foould be
| found to take place in any of them, and fuch other Data fbouid be-
_ procured from Oxfervations, as would be farther neceffary for-
that Purpofe. By the Rev. John. Michell, B: D. PLR. So
In a Letter to Henry Cavendifh, E/g. P.R.S and A. S..
RSS
VIII. A Meteorological ‘fournal for the Year 1782, kept at
Mitiehead, # Somerfetthire.. “By Mr.. John: Atkins 5. com-
municated by Sir Jofeph Banks, Bart. P. R. S. p- 58:
IX. Defcription of a Meteor, obferved Aug.. 18, 1783; By Mr.
Tiberius Cavallo, F. R.S. p- 108
K. An Account of the. Meteors of the 18th of Augutt and.sth
‘of O&tober, 1783. By Alex. Aubert, E/q... FR. S. andS. A,
p- 112
XI. Obfervations on a remarkable Meteor feen on the 8th of
Auguft, 17833; communicated in a Letter to.Sir Joleph Banks, .
Bart. P.R.S. By Willam Cooper, D. D. F.R.S. Areh-
deacon of Y ork. p-. 116
XU. An Account of the Meteor of the 18th of Auguft, 1783.. In
a Letter from Richard Lovell Edgeworth, E/7. FR. 8. to
Sir Jofeph Banks, Bart. P. R. sue p. 118:
XI. Experiments on Air.. By Henry Cavendith,. E/y. FR. &
oS. A. p-.119
XIV. Remarks on Mr. Cavendifh’s Experiments on Air. Ina
Letter from Richard Kirwan, Ef. F. R.S. to. Sir Jofeph
Ganks>: Bart. P. Bede. ea.
XV.
Cy OU IN tee NT Ie vi
XV. Anfwer to Mr. Kirwan’s Remarks upon the Experiments on
Zur. By Henry Cavendith, B/g. FP. R.S. andS. a4. p.t7o
XVI. Reply to Mr. Cavendifh’s dnfwer. By Richard Kirw:
yy. BRS. Dp: “8
XVI. On a Method of defcribing the relative Pofitions and Maz-
nitudes of the. Fixed Stars; together with fome. she riient Gi
Obfervations. By the Rev. Francis Wollafton, LL.B.
me RS. Dp. Tot
XVUI. An Account of fome late fiery Meteors ; with Obferva-
tiohs. Ina Letter from Charles Blagden, M.D. Phyfician to
the. Ae Sec. R.S. to Sir wa Banks} BaricoR, RSs
A cid pAZewt
“
THE Prefident and Council of the Royal Society adjudged,
for the laft Year, 1783, Two Medals on Sir Goprrey
CopLey’s Donation; One to JoHn Goopricxe, Efg..
for his Difcovery of the Period of the Variation of Light
in the Star Algol; and the other to Tuomas HuTcuins,.
E({g..for his Experiments to afcertain. the Point of Mercurial.
Congelation.
Ek @ 42 7 &
Page. Line.
117. 7+ for canon read cannon
164. 9g. for not read nor
18x. 8. for called read call
211. 7. for Tweed read Clyde
224. 4. for of read or
PHIL OS OO PH ICG A L
T RAN SAVE TE O Nes!
I. An Obfervation of the Variation of Light in the Star Algol.
In. a Letter from Sir Henry C. Englefield, Bart. FR. S.
and S, A. to Jofeph Planta, E/g. Sec. R. S.
Read November 6, 1783.
§ LR; | _ July 3, 1783;
"AVING been fortunate ee from the finenefs of |
the laft night, to make a fatisfactory obfervation of the.
variation of Algol, I lofe no time in ee it to the
Society.
The laft vifible period was June sha roth, : when», Mr...
AUBERT, as well as myfelf, obferved it, though imperfectly,
~ Vor. LXXIV. B and
2 ‘Sir H. C. Encierieiy’s Obfervation of the
and thought the time of its greateft diminution was about 22 h.
in the morning; calculating from thence by Mr. GooprickeE’s
period of 2 d. 20h. 48’, the time of leaft brightnefs was to “8
about one o'clock this morning. ‘
All the following obfervations were made with an excellent
night-glafs, magnifying about eight times, witha field of 5°,
in which therefore Algol and the p were diftinétly vifible at
once.
I firft looked out at midnight, and readily found the ftar,
though hardly vifible to the naked eye from the vapours near
the horizon. It appeared much bigger than the g, and full as
big again as the z, alfo in the.field at the fame time.
At 123 h. I looked again, and faw but little difference, as
Algol was then alfo evidently much fe cs than g. I at that
time faintly peagcven it with with the naked eye.
At 1h. ro’ the ftar was but very little bigger than p, the
diminution having gone on moft rapidly in the interval be-
tween the two laft obfervations. ‘Though higher above the
horizon it was much lefs (if at all) vifible to the naked eye.
At 1h. 35’ it was, I think, diminifhed (though but little)
fince the former obfervation. It was ftill, however, a very
little larger than , but notat all vifible to the naked eye.
At 2 h. it was fcarce at all altered from the laft obfervation ;
but, if any thing, feemed recovering its light.
F had meant to obferve its progrefs {till further; but return-
ing to the glafs at half an hour after two, clouds had. fuddenly
covered the whole fky.
The fact of the diminution of Algol is, newer fully
confirmed (if confirmation was wanting) by this obfervation,.
and the cecuracy of the period fixed by Mr. Goopricke afcer-
tained,,.
DS!
Variation of Light in the Star Algol. 3
tained, as the phenomenon was certainly within half an hour
of the time fixed by Mr. Goopricxe, which, divided on eight
periods, gives only an error of four minutes on the length of
it; and a nearer coincidence is not to be expected in a matter
of this nature, where eftimation 1s the only means of deter-
mining the brightnefs, and two perfons can hardly agree within
a few minutes, from the difference of fight.
Tam, &c.
Aaah
BP Ok aie €:
ef2€s as Ae
20 OS
F «
‘a gy Rata e
ne Olevia on the Obfewration a the Star. Algol, id Petre s
_4, Farmer. Communicated in a Letter fram the Count de
_Brubl eR iS Sir Jofeph Banks, Bart. P. R. S.
Read November 13, 1783.
Nov. 7, 1783.
Sek B
y) Dover-Street,
AVAIL myfelf of the permiffion you gave me, when I
had the honour to meet you yefterday in the Drawing-room,
by fending you the following fhort account, which was tranf-
mitted to me. by Mr. CanzLex,. one of the Elector’s Libra-
rians, dated Drefden.the roth of Ogtober. Patircu, a far-
mer of Prolitz,‘a village in the neighbourhood of that Refi-
dence, faw the greateft obfcuration of Algol on the 12th of
September, at eight o’clock, P. M. On ‘the 2d and sth of
Oétober he obferved the fame phanomenon again. On the sth
the greateft diminution of that ftar’s light happened fome mi-
nutes before feven, when he judged it nearly of the fize of a
{tar of the fourth magnitude: it continued increafing in bright-
nef{s till a quarter paft ten in the evening, at which time it had
entirely recovered its ufual brillancy and fize. From his own
ebfervations he eftimates the period of that remarkable phano-
menon at 2 days 20 hours 53 minutes.
I have the honour to be, &c.
tan
Ill. Further Odbjervations upon Algol. By the fame.
Read January 15, 1784.
CT. 20th, Parircs faw Algol nearly at its greateft ob-
{curation, at 3 o'clock in the morning.
O&t. 22d, near 12 P. M. he obferved it again in the fame
flate. |
O&. 25th, at about 9 P. M. it appeared to him like a flar of
the third magnitude. He was prevented by clouds from making
long obfervations; but as all thofe he has had opportunities to
make, indicate a period fomewhat longer than that of 2 days
20h. 51’ he is inclined to think that half the difference
between that period and his. own, viz. 2.d. 20h. 52’ will
come very near the truth. eo
preg
7.
IV. Defcriptions of the King's Wells at Sheernefs, Languard-
Fort, and Harwich. By Sir Thomas Hyde Page, Kat.
F,R.S.; communicated by Lieut. Gen. Rainsford, F. R. 5.
Read November 13, 1783.
LIEUT. GEN. RAINSFQRD.
STR, ee es
HAD the pleafure to receive your obliging letter of the
28th ult. mentioning, that it would be fatisfactory to the
Royal Society to have a defcription of the wells at Sheernefs,
Harwich, and Languard-Fort, which were made under my
direction, whilft I commanded as Engineer at thofe places.
I beg to acquaint you, that it will be neceflary to mention
fome previous circumftances that occafioned thofe undertakings,
which will rather interfere with the defcriptive part, and I fear
intrude on the patience of the Society; but I fhall in this re-
{pect hope for their indulgence, it being my with to explain
the nature of the different operations as fully as poffible, that
fimilar fituations, where water is wanted, may receive benefit
from the experiments I have had the good fortune to fucceed
in; and it cannot fail of affording me the higheft fatisfaction to
have an opportunity of communicating this fubject to the
knowledge of the public through the Royal Society.
i I have
Sir T. H. Pace’s Deferiptions of ihe King’s Wells, &e. 7
I have only further to requeft, that you will do me the ho-
nour to lay the following de{criptions before Sir Josep Banxs
and the Society ; and as you are fully acquainted with: the fub-
ject, you will confer on me an additional favour by explaining,
the feveral parts (if requifite) more fully than I have done in,
the written. account, when it is under confideration.
Fam, &c..
Some circumftances refpecting the garrifons of Sheernefs, Land-.
guard-Fort, and the Town of Harwich, with a defcription of
the wells which Jupply water for the ufe of the troops, &c. at
each place.
The Mafter-general of the Ordnance (Lord TownsHenp),
in the beginning of the year 1778, recommended to his Ma-:
jefty,. that the fortifications upon the Eaftern Coaft, including.
Dover, Sheernefs, Landguard-Fort, and fome other places,,
fhould be repaired,, and new works added, where they might.
appear neceflary towards a proper ftate of defence, if a war
with Holland, or other Northern. powers, was found una--
voidable. His lordfhip forefaw the great objection to fortifica-
tions, in the want of frefh water under the command of the
guns of our garrifons; and I had direétions accordingly to con=
fider the fubje@t, and report to his lordfhip and the Board of
Ordnance any ideas that might be likely to remedy fo great a
defect.
The dock-yard and garrifon at Sheernefs were fupplied with:
water fram Chatham at an enormous expence, near two thou-
fand:
08 Sir T. H. Pacer’s Deferiptions of the -
fand pounds per annum, or occafionally from Queenborough,
neither of which fupplies could be continued in cafe of a fiege,
which of courfe would be of fhort:duration from this cireum-
flance. Some attempts had been. made in former times to ob-
tain water on the fpot, by finking wells, but they had failed;
and fuccefs in fuch undertakings was at laft confidered as impof-
fible, from the great difficulty they had met with in the vaft
quantities of fea-water, that came by filtration through the
{ands into their wells, and rendered a progrefs to any con-
fiderable depth impraéticable. It is probable, that the courfe
of the river Medway has undergone many changes, and had
once an out-fall to the fea, near the high ground of the Ifle of
Shepey. The docks, garrifons, buildings, &c. for a confi-
derable diftance into the ifland, confequently ftand upon very
loofe materials, which were found, upon finking the well in
Fort Townfhend, to confift of mud, fea-beach, and quick-
fand, nearly to the prefent depth of the river Medway, and
admit fo ftrong a filtration of falt-water, as muft ever render
the finking of wells exceedingly difficult. ‘This was the fitua-
tion in which I found Sheernefs.
Landguard-Fort was not more eligible refpecting water, asa
place of ftrength. It was, indeed, better fupplied under any
other confideration, a pipe beang laid into the place from a good
{pring about two miles diftant, which furnifhed a plentiful
quantity of water; but fuch is the difadvantage of fituation
that, in cafe of attack, that {pring muft fall into the pofleffion
of the enemy, and our garrifon of courfe would be deprived of
its ufe. This was a ferious confideration and objection toa
great extent of fortification, however eligible in other refpects
the place might be.
Harwich
3
King’s Wells at Sheernefs, &e. 9
Harwich was judged by the Commander in Chief (Lord
AmuERST) to be a very proper ftation for a confiderable part
of the army, in time of war with Holland, as centrical to
furnifh detachments for fuch parts of the coaft as might be in
danger, as alfo to cover a very ufeful harbour and increafing
dock-yard; but his lordfhip was fenfible of the want of whole-
-fome water in that neighbourhood, and gave particular direc-
tions to eftablifh fuch a fupply for the camp to be formed
there, as might appear proper for the health of the troops;
and the fubfequent orders given by General RainsForp, who
commanded that diftrict, perfeétly anfwered every defirable
end, until good water was found within his camp. The inha-
bitants of the town of Harwich had chiefly depended on rains
for their fupply, the wells being in general brackifh from the
filtration of falt-water. The neighbourhood, to many miles
diftance, was not better furnifhed, there being only ftagnating
water in ponds or fhallow wells, which were fupplied from the
upper furface of the ground; and, whether rendered bad by a
mixture of copperas, or other mineral, it was not fuch as could
be given for the ufe of the troops with any degree of prudence
or attention to their health, and they were, to avoid dangerous
confequences, furnifhed with water, by General RAiNsrorpD’s
order, from the oppofite fide of the Manningtree River, by
boats employed for that Buel the beginning of the firft
campaign.
I will now endeavour to defcribe the experiments at each
place, beginning with the ‘well in Fort Townfhend at Sheer-
nefs, which with a reference to the plans will, I hope, render
the fubject fufficiently intelligible.
Vou. LXXIV. ‘a King’s
10 Sir 'T. H. Pace’s Deferiptions of the
King’s Well, Fort Townfbend, Sheernefs.
\
This undertaking was.at firft confidered as a mere experi-
ment, the probability of fuccefs being much againft it; I
however thought the attempt, where a dock-yard of great con-
fequence to the navy was eftablifhed, fhould be made, and car-.
ried as far as it could, with a proper attention to economy in
laying out the money of the public. Such was my opinion
fignified.to the Mafter-general and the Board of Ordnance. I
received an anfwer thereto, expreflive of approbation, and full
powers to employ proper perfons, and proceed upon the
undertaking.
‘Vhefe previous fteps feemed highly neceflary, as in all works
of difficulty, great confidence is as much required as able work-
men or good plaus.
The favourable opinion his Majefty was gracioufly pleafed to.
exprefs publicly of the projeét, when he vifited Sheernefs, and.
{aw the well, tended very much towards its final fuccefs; and
the countenance and fupport of General Craic, governor of —
that garrifon, greatly promoted perfeverance in a work of fusli
difficulty.
I employed a very ingenious man, Mr. Cote, engine-maker,
of Lambeth, as a chief perfon in this bufinefs, and received’
every afliftance I expected from his experience and judgement in
mechanics ; and it is but juftice to him to exprefs, that the fuc-
cefs of the work greatly depended on his attention and the able:
afliftants he procured from diftant parts of the kingdom.
The greateft acknowledgement is alfo due to the ability of
Lieut. HumrFrys, of the Engineers, and Mr. MarsHatt, the
Ordnance-overicer, who were conftantly on the {fpot, and car-
3 ried
King’s Wells at Sheernefs, @e. it
ried my orders into execution with the greateft zeal for the
fuccets of the undertaking as well as judgement. The men-
tioning thefe gentlemen’s names is, as well asa juftice to their
conduct, to recommend harmony and mutual exertion in any
future work of this nature, as, without an equal attention in
every one, I fhould greatly doubt fuccefs, even admitting the
fame plan to be in all other refpects {trictly attended to, as
there would be great difficulty and danger to the lives of the
workmen if carelefsly carried on.
The work was begun the 4th of June, 1781, and finifhed
the 4th of July, 1782. |
A circle of twenty-two feet diameter was firft marked out
on the ground, and the {pace excavated to the depth of five
feet ; after which, pieces of wood, called ribs, upon the curve
of a diameter twenty-one feet four inches, and about nine
inches fcantling, were placed, to form a complete circle within
the excavated part at the bottom, above which other circles
of the fame nature were placed, and fupported by upright
pieces of fcantlings, having fhort boards introduced by the in-
tervals, which afterwards prefled upon the circles or ribs, be-
tween them and the exterior parts. Thefe, when united,
formed one frame of wood from the bottom to the top, or
rather higher than the excavated fpace, and prevented the mud
of the upper furface, which was very foft, from falling in upon
the workmen. In proceeding deeper, care was taken to pre-
vent the finking of the before-mentioned frame by its own
weight, in excavating parts only under it till another circle of
pieces like the firft, called ribs, was formed, and uprights,
with boards behind, introduced. The diftance between thefe
circles was in the firft, or upper part of the work, about three
feet ; but as difficulties increafed they were placed nearer, and
Ci2 in
12 ‘Sir’. H. Pacn’s Defcriptions of the
in many parts joined each other‘without any boards or uprights
(as will appear in the fection of the plan), and continued
through the whole of the wooden frame, againft the weight of
the mud, quick- -fand, and fea-beach, to the ore of ——
fix feet.
The reafon of the circular frames being nearer in fome pad
than in others, arofe from the greater or lefs quantity of falt-
water that came through the fands, &c. and often rendered it
impoffible to fink under the frame more than the thicknefs of
one of the ribs, without danger of blowing up, or of the fides
behind the wood flipping with the ftreams of water, and thereby
forcing into the bottom of the well, which in finking through
very wet quick-{fand is much to be apprehended; and an acci-
dent of that nature would entirely deftroy the work. An at-
tention to the plan will fhew at what depths the filtration of
water was moit dangerous, and the difficulties at different periods,
may be eftimated by the diftance of the circles, formed of
ribs, from each other, and where they appear to join, it was
not without the utmoft efforts of labour that the work could
be carried on. At the depth of thirty-fix feet the wood-work
was finifhed, and fix feet deeper a firm foundation of hard blue
clay difcovered. The feveral parts of the frame were then
{trengthened wherever it appeared neceflary, to prevent fepara-
tion, and to refift the immenfe prefiure of foft mud, quick-
fand, and loofe fea-beach, which were fupported by it.
It muft be obferved, that the falt-water, after proceeding
thus far, came in very faft through all the joints of the frame,
and that holes were left on purpofe in certain parts to let it run
into the well, that it might not be confined entirely to the
bottom of the work, which, from the weight upon one part
only,
oe
King’s Wells at Sheernefs, &c. 13
only, might have blown, whicli is ever (as has been obferyed)
to be guarded againft with the utmoft caution.
‘The frame being found of fufficient ftrength, and the work-
men able, by con{tant drawing with four 36-gallon buckets,
to keep the bottom of the well dry enough to proceed further,
the greateft difficulty feemed to be overcome, The next procefs
was to cut off or ftop the falt-water out entirely: to effe
which, a fmaller circle was defcribed at the bottom of the well,
upon the hard clay already mentioned, of the diameter of eight
feet in the clear, round which a curb, or circular frame of
wood, was laid, and a brick fteening, of two bricks thick in
tarris, raifed gradually towards the top of the well, whilft, as
it proceeded upwards, the {pace between the back of this fteen--
ing and the wooden frame (fixed fix feet higher) was filled with
good tempered clay, four feet thick, and carefully rammed.
During this operation,and raifing the brick-work, with the clay
behind it, the water continued to run over them into the center
of the well, now reduced to eight feet diameter, and was con-
ftantly drawn out, to leave the workmen on the fides fufficiently
dry to raife their work until they had reached the top, and confe-
quently, as it was water-tight, cut off the filtration from the
fea, precautions having been taken to prevent the danger of
blowing at the bottom.
The next proceeding appeared more fimple; but great care
was till neceflary to avoid damaging the foundation of the
works already done, as the leaft crack might have again intro-
duced the falt-water. A fmaller circle than the laft was there-
fore defcribed, and ribs; forming circles of wood, raifed fome
feet within the brick-work; and others, of the fame form,
were funk to the depth of eight feet below the bottom, upon
which the feveral works already defcribed xefted, After this a
courte
14 Sir 'T. H. Pace’s Deferiptions of the
courfe of bricks was carried up within the laft mentioned ribs
or circles, upon a diameter of fix feet, whereby they became
inclofed and joined with the firft mentioned brick-work, having
the clay wall and wooden frame prefling behind them upon
larger diameters. In finking lower, {mall curbs were at certain
diftances (as will appear in the fection of the plan) placed to
fupport the fteening, which confifted of two ftretching courfes
of bricks, laid feparately, and keyed into the clay or back
part of the brick-work by rough pieces of ftone, flint, &c. to
prevent a flipping or lowering of the fteening by its own
weight. The work was carried on from this period, without
any material difficulty or difference in the clay (except the
very extraordinary difcovery of a piece of a tree at the depth of
300 feet from the top of the well, which is fhewn in the plan)
until the appearance of water at 328 feet deep, by a {mall
mixture of fand in the clay, with oozing of water from it;
and at 330 feet deep, upon boring, the whole bottom of the
well blew up, and it was with difficulty the workmen efcaped
the torrents of water that followed them, which was mixed
with a quick-fand that rofe forty feet in the bottom of the well,
at which height it fill remains. The water rofe in fix hours
189 feet, and in a few days within eight feet of the top of the
well. It has fince been carefully analyzed by a chemift, and
found perfe€tly good for every purpofe; and, it is prefumed, the
quantity will be equal to every demand of public and private
ufe at that place, as there has been, ever fince it was firft dif-
covered, aconftant drawing of water, and it has hitherto been
found impoflible to lower the well more than 200 feet, there
has confequently always been a depth left in water of 130 feet.
Tt is to be remarked, that the water is of a very foft quality,
and, upon being drawn, has a degree of warmth unufual in
common
King’s Wells at Sheernefs, Gc. 15
common well-water. it remains yet to be determined whence
that warmth proceeds; but as it proved wholefome, the cir-
cumftance is fortunate for the foldiers of the garrifon, as they
will not be liable to complaints that are fo frequent among
troops (as often happens at Dover Caftle) from imprudence in
drinking great quantities of very cold well-water.
King’s Wells at Landguard-Fort.
They were begun and finifhed in the year 178.2.
The peculiar fituation of this fort made it very unlikely that
fprings of frefh-water could ever be found, there being great
reafon to think, that the out-fall of the Ip{wich and Manning-
tree Rivers, which unite before they reach they fea, was for-
merly on the Suffolk fide of the fort, but is now on the Effex
fide; and as the garrifon, in ancient writings, is defcribed to
have been built on the Andrew’s Sand, there appeared. little
probability of any filtration of water through it, except that of
the fea. It, however, feemed proper to try the poflibility of
finking through it, to endeavour to find a hard bottom, fimilar
to that difcovered at Sheernefs, frefh-water being of vaft confe-
quence to the defence of the place. The work was accordingly
begun ; but about the fame time, m making the excavation of a.
ditch for one of the batteries, at a very few feet. from the
upper furface of the fand, a {mall quantity of frefh-water was
perceived; and it was chance that led to a difcovery of its
frefhnefs, from one of the labourers happening to tafte it. The
circumftance
16 Sir 'T’. H. Pace’s Deferiptions of the
- circumftance was reported to me by Mr. Rozerts, the Adjutant
of the Works; and we, upon examining further, found that
the quantity of water upon finking was confiderable, and that.
it appeared perfectly frefh. I then ordered the well-finkers to
proceed to this depth at another place, where they founda
like appearance of good water; and the quantity was fo great,
as to render it very difficult to keep the bottom of the well, at
twelve feet deep, dry enough to fink further. Every exertion
was notwithftanding ufed, and with great labour a well was
funk to the depth of low water mark at fpring tides, about
eighteen feet from the upper furface of the fand; when, tothe
furprize of every perfon, the water that rofe from the bottom
became, on a fudden, entirely falt. This put an end to the
work fora time, asit feemed impoffible to penetrate deeper. I
then confidered the matter very differently with my firft idea,
and though the impoffibility of having a deep well clearly
appeared, there remained a profpect of a fufficient fupply of
good frefh water. It may now be neceffary to recolleé, that
at avery few feet from the furface (eight feet) there was good
water; that it continued in vaft quantity almoft to the {pring
tide low-water-mark, after which the falt-water had appeared ;
I therefore directed fand to be thrown into the well, to bring it
a little above what had been the lowe fre/b-water line (twelve
feet from the upper furface) and then drew the water out which
had mixed. After this, the filtration into the well became again
perfectly frefh, and in equal quantity to the firft appearance.
This was, therefore, fixed as the greateft depth (twelve feet)
and another well funk at forty feet diftance, with a horizontal
brick drain, having holes left in the fides for filtration, as de-
{cribed in the plan, to colle& the water, and the bottoms of
both wells were fecured with hard materials; that the whole
4 fupply
King’s Wells at Sheernefs, &c. 17
‘upply of water might be reduced to the drain, which is con-
tru€ed to prevent as much as poffible the mixture of fand
with the water, and is found to anfwer the defired end. This
fuccefs'arofe from various unexpected circumftances ; but I am
yet at. a-lofs for the caufe of the frefh water, or whence it
comes.
I conceive, that oy is a certain diftance from the fea, upon
every fandy fhore, to which, the falt-water penetrates, where it
is forced whilft the tide is at its greateft height ; and that fuch
water, when fo far preffed into the fands, has an aétion back
towards the fea again, as the tide falls, and continues to have it
until another tide makes it revert; this may account for the
filtration of falt-water a certain way into a country; and that
further, from probably higher Jurfaces, there may be frefh-water
in the fame continuation of fands, and the feparation difco-
verable to a degree of great accuracy; whether this a¢tion of
falt-water in the fand, by friGtion, can render it frefh, or of a
lefs degree of falt, I will not pretend to judge. I prefume the
contrary ; but am even under that idea at a lofs: to know how
fo much frefh water gets into the fand at Landguard-Fort, it
being fo entirely feparated from the {pring of the country. It
is evident, upon a full confideration of the fubjeét, that the
fea, to the height of Jow water; will penetrate a vaft diftance
into a fandy country, by filtration; and to that height on/y, it
having fo fara conftant preffure, and no reraction; the water,
therefore, being once in the fand, can never return by the fame
paflage, the caufe of its entrance ftill remaining; whereasin
the higher furfaces, the rife'and fall of tides muft keep it in
conftant movement, and the diftance of filtration will bear a
proportion to the duration of preffure which gave it original
motion. It is probably not fo eafy to account for a body of
Vor. LXXIy. 1G BD _. -fxefhe
ie a Sir Ke i. Pcr’s Deferiptions of the
freth-water being to ‘the ‘depth of twelve feet'in the fand, and
in the fame line, a few” feet’ deeper, the’ water fhould be én=
tirely falt, and that’ they do not mix together. Whether thé
greater fpécific g gravity of ‘the falt-water is fufficient to prevent.
a mixture with the ftefh upon a higher line, I cannot venturé
to fay; but the fact of there being a feparation is beyond a:
doubt, and ‘the depths thay be afcertained to a degree: of
great accuracy. However this may be accounted for, the
difcovery at Landguard Fort is of Very great confequence to
the garrifon ; and ‘there is’ reafon to think, that in fimilar
fituations, where water ‘is wanted, an attention to — has
been already exphatiert nes be found as tHE, © |
Van)
King’ s Wells at Harwich.
‘They were ‘bogie the 6th a May, £781, upon, General
RaAINsForD’s taking the command at that Slate and fnithed
the 29th of September following.
The wells in this neighbourhood, as has already been she
ferved, being very fhallaw, and only depending on {prings
from the upper furfaces of the ground, have but little! water.in
the fummer, ard the quality of it is very bad. The beft of
the old wells was in the rear of General RAINSFORD’s camp,
and was thought of at firft for the ufe of the troops; but he
prudently declined that fupply. It was:imagined, as the water
from. the upper furface was of a bad quality, that the moft
likely way to ‘obtain a better {pring was to fink a well from
higher ground, and to endeavour to penetrate through a,rock
which lay a few yards under the level of the country, although
the operation might be tedious, upon the chance of cutting a
fpring
King’s Wells at Sheernefs, Ge. ig
fpring of better water, that might be unconnected with the
Jand-drains. ‘The experiment anfwered in every refpeét, as
there was not a drop of water found till the rock had been en-
tirely cut through, when, upon finding a confiderable quantity
of moift fand, and boring into it, a plentiful {pring was difco-
vered, and has fupplied the troops ever fince with very good
water. Itis probable this fupply, the {pring being very power-
ful, will be found equal to every demand for public and pri-
vate purpofes, in the dryeft feafons. After this fuccefs, as mat-
ter of curiofity, an old well was made deeper, by ex¢avating
through the rocks; where a good {pring was alfo found; but
as that well had been originally funk from low ground, a great
deal of the bad water from the upper drains, &c. mixes with
it, and gives ita difagreeable tafte.
The plans will defcribe the manner of making thefe wells
fufficiently. I have chiefly dwelt on the defcriptive part, to
recommend, where it is apprehended any mineral or drain from
the Upper furface of lands, by mixing in wells, may hurt the
water, the finking’ from the heights, : as there are few coun-
tries where very good water may not be found, bys a iptotet
attention to ‘adore? in ota 4 wells.
o EXPLANATION oF ‘THE PLATES.
Tab, I, fig. I. Seétion of the King’ $ Well i in cele: Townthend
St Shéernefs/ |
2s Plan of the frarne and well.
3. Section of the frame AA.
4. Plan of the well.
Tab. I]. X. Line of high-water mark.
Y. Line of low-water mark.
Z. Line of low-water at {pring-tides.
D2
baa 7
YV.. Extrad i a Letter from Edward Pigott, E/7. to M. de
“Magellan, F. R.S.3 containing the Difcovery of a Comet.
Read November 27, 1783.
S$ I Bs. York, Nov. 22, 1783.
T HAVE the pleafure of informing you, that I difcovered a
comet on the 19th inftant, and have 2a the following:
obfervations on it.
Date. Rea North Decl.
re scala « Caron Our ag Swe
Nov ig IEF 85 - 43 0 ~ i gros
20 10 54 . 40 0 - 4 1)
Nov. 21. This night I faw the comet where I expetted it,
according to the above determinations; but could not obferve it
with an inftrument. | sles 5c
The comet looks like a nebula, with a diameter of about:
two minutes ofadegree. ‘The nucleus being very faint, is feen |
with fome difficulty, when the wires of the inftrument:are
illuminated. It is not vifible with.an opera glafs.
Philos. Trans. Volt LXXIV. Tab.L. p. 20,
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VI: Project for a new Divifion of the Quadrant; By Charles,
Hutton, LL.D, F.R.S. In a Letter to the Rev. Dr..
Mafkelyne, F..R. S..and Afironomer Royal.
Read November 27, 1783.
Royal. Mil, Acad. Woolwich,..
Aug. 12, 1782.
DEAR SIR,
AVING long: fince thought it:would be a, meritorious.
and ufeful fervice, to adapt the tables-of. fines, tangents,
and fecants, to equal parts of the radius.inftead of to thofe of ’
the quadrants. and having frequently. mentioned this-project ta.
you, sIR, as.a proper judge and promoter of: all ufeful um-
provements in fcience; I now beg leave to lay before you fome
obfervations I have thrown together on the. fubje@, with a view -
to ftimulate others, either to undertake and calculate fome part.
of fo large and painful a work, or to communicate farther hints.
for the improvement and eafier performance of it.
Ihave the honour to be, &c..
Al project:
ee Dr. Hurton’s Proje far a
if afta di confructing fines, tangents, aati yn to eae
parts of ibe radius.
1. The arbitrary divifion of the quadrant of the circle into
equal parts by 60ths, which has been delivered down to us from
the ancients, and gradually extended by fimilar fub-divifions
by the moderns, among various ufes, ferves for trigonometrical
and other mathematical operations, by adapting to thofe divi-
fions of the arc, certain lines expreffed in equal parts of the
radius, as chords, fines, tangents, &c. But among all the im-
provements in this ufeful branch of fcience, I have long withed
to fee a fet of tables of fines, tangents, fecants, &c. con
ftru€ted to the arcs of the quadrant as divided into the like
equal parts of the radius as thofé lines themfelves. In this
natural way, the arcs would not be exprefled by divifions of
6oths, in degrees, minutes, &c., but by the common decimal
feale of numbers; and the real lengths of the arcs, expreffed i in
fuch common numbers, would then ftand oppofite their refpective
fines, tangents, &c. The ufes of fuch an alteration would
be many and great, and are too obvious and important to need
pointing out or enforcing. I have therefore had fora long
time a great defire to commence this arduous tafk; but conti-
nual interruptions have hitherto prevented me from making any
confiderable progrefs in fo defirable an undertaking. But I am
not without hopes that fome future occafion may prove more
propitious to my ardent wifhes. It is not, however, to be ex-
pected, that this work can be accomplifhed by the labours of
one perfon only ; it will require rather the united endeavours
of many. I fhall therefore explain a few particulars relative to
my project of this work, with a view to obtain from others,
who
new Divifion of the Quadrant. 23
who may have leifure and abilities for it, their kind affiftance,
either by communicating hints of improvements, or by under-
taking fome part of the computations, to which they may be
excited by their zeal for the accomplifhment of fo important a
work, and by the extreme facility with which the calculations
in this way are made. ©
2. In the firft place then I would obferve, that I think it
will be fufficient to print the fines, tangents, &c. to: feven
places of figures; and that therefore it will be neceflary to
compute them to ten places, m order effeCtually to fecure the
truth of the feventh place to the neareft unit.
2. I would affume the radius equal to 100000; or fuppofe it
to. be divided into 100000 equal parts. Then it is well.
known, that the femi-circumference will be 314159°26536.
nearly, and confequently the quadrant nearly. 157079:63268:
of the fame equal parts, which is lefs than 157080 by 36732,
er nearly 2 of an unit, or nearer 2=°375;.or nearer {4p =:
3636, or ftill nearer 7,="3684, or ftill nearer 14 =-36666
&c. And the half quadrant, or x of the circle, 78539:81634.
which is lefs than 78540 by only °18366, or nearly 3 only of:
any of the above-mentioned fradtions.
4. The table. may confift of five or more columns; the firft-
column to contain the regular arithmetical feries of arcs differ-
ing by unity, from the beginning, .in this manner, 1, 2, 3,.45 55.
&c. up to half the quadrant, the next lefs whole number:
being 78539; then for the higher numbers, or thofe in the
latter half quadrant, befides adding 1 continually, there muft:
be at the firft added the decimal -63268, which will make alt:
the numbers in this: half become the exaét complements of. the:
, firft half, which confifts of whole numbers only; and thefe
will be the lengths of the arcs. Or, in order to include the:
| Ze quadrantal:
24 : Dr. Hur ton's Project for a
quadrantal arc 78539'81634, the firft column may be conti-
nued up to 78540. The fecend column to contain the cor-
refponding degrees, minutes and feconds to the neareft fecond,
or to the true feconds and decimals of a fecond, for the conve-
nience of eafily changing the tables from the one meafure to
the other, or to make them anfwer to both methods; and the
3d, 4th, sth, &c. columns to contain the correfponding -_
tangeuts, fecants, &c.
5. The tables may be difpofed as at prefent, namely, conti-
nuing them downwards by the left-hand fide of the pages, as
far as to the middle of the quadrant, and then returning them
again backwards and upwards by the right-hand fide of the
pages.
6. In this difpofition, the numbers on the fame line, an one
on the left and the other on the right, will be exact comple-
ments of each other to a quadrant, and the decimal :63268, in
every number in the latter half quadrant, in each page, namely,
either at the bottom of the column, or length-ways on the
fides of it. I |
77 A
new Divifion of the Quadrant. 25
>. A fpecimen of the firft page of the table will therefore
be this :
°
AES) tan ujes: .Tang.,.], Secants. Sige ce Cot | ung Ares
© {0 © ojcocc0"o0 |o0000"00 mobee-ce| infin, | infin. 100000°00}90 O10} 79
I 2 1°00 78
2 4 2,500
3 ha acai ha
4a is 4°00) 75
&e. | Bec.
80 |
. i
3
oy
3 o
&e. Bec.
96 83 2)
98 |
99 So |
res | Orin | Cotan, | Cofec. |\Secants.|Tang.| Sines. | ° ’ “’} Arcs
8. To fill up the fecond column. Since the length of the
quadrant is 157079°63267948966, and the number of feconds
in the quadrant is go x 60 x 60 = 3240003 therefore, as
: 157079°632 &c. > 324000 :: I : 2:062648062470964 = the
- number of feconds anfwering to each unit in our divifion of the
quadrant, and which therefore being continually added will
fill up the fecond column.
9. The number of feconds to be continually added being 2,
_and the decimal -062648062470964, which is nearly equal
i 3. Ome as. 70625 5 therefore, befides adding 2 every time,
VoL. LXYEXIV. 12 we
26 Dr. Hurton’s Projed for a
we muft alfo add 1’ more at every 16, which will make 3” to
be added at every 16th time, and 2” at every other time befides ;
but the firft time the 3” muft be added will be at the arc or
number 8, to have them to the neareft fecond, the repetition
of the fraction at the arc 8 amounting to above 3 a fecond;
and then the 3” muft be added at every 16 afterwards, vz. at
BY) 4051 505 7 2p 005» TOAL: SEC. |
10. But befides the conftant addition of 2” every time, and
of 1’ more every 16th time, there muft be 1” more added for
every 67533 time, on account of the excefs of the fraGion
°062648062470964 over the frattion ‘o625 or ,*.: for that
excefs is °000148062470964 which a pepe And the eafieft
‘ 2
method of making this laft addition of 1 at every 67534, will
be to make the increafe of the 1 on account of the ., at an
unit fooner for every 4223.; becaufe 16 is 4223. times con-
tained in 67534; by which means the incremental units for
the *, will become 1 more at that number 67534, which laft
unit may be confidered as the increment of the former incre-
ment for the ,*,, and fo proceed up to the quadrant; which
will complete the fecond column of arcs to the neareft fecond
in each number. Or this fecond column may be exaétly com-
puted to as many decimals as we pleafe, by adding continually
the 2” and decimals, w/z. 2°062648062470964. But at the
middle of the quadrant, where the numbers return again up-
wards by the right-hand, there will for once be to be added
only the feconds and decimals anfwering to the arc *63268,
viz. 1°30499618 feconds, that number being neceflary to make
the numbers on the right-hand to be the exact complements
of thofe on the left. Or it will, perhaps, be proper to make
them to the neareft unit in the 6th place of decimals. And to
4 | fill.
new Divifion of the Quadrant. 27
fill up the fecond column to this degree of accuracy, add con-
tinually 2°:062648 feconds, but at the gth line add x more, or
2°062649, becaufe 9 times 062470964 amounts to 56223867,
or more than half a unit at that place ; and after that add 1 more
than 2°062648 at every 16th line, viz. at 25, 41, 57, 73, &c-
becaufe 16 times 062470964 amounts to -g9953542, or nearly
1, it being only -o0046458 lefs than 1. And this number
700046458, thus added too much, will, in 134 times adding
it, amount to more than 06223867, the excels of 56223867
above 5, or half a unit, at that place; therefore at the line or
number 2153 (or 9 +16 x 134) which would be to have the
1 more added, let the r be there omitted, and add it at the
next line or 2154, the true decimals after the firft fix, for 215 3
being 499985, and for 2154 they are 562456. Continue thus
always adding 1 more at every 16th line, except at the fol-
lowing numbers, where the 1 must be omitted, and added at
_ the next following number; vz.
2153/10765|19377|27989
36601 53825
45253 62437|71033}
4314:12926)21 538/303 50/38746]473 58/5 5970164582173 104
6459)15071'23683)32295140907/4951915813 1166743175339)
|8620|17232|25844|344.56|43052|51664|60276 68888|77 500
And thus proceed to the middle of the quadrant ; by which
means all the numbers will be to the neareft unit in the fixth
or laft place. Alfo, to have a check upon thefe numbers at
certain intervals, it may be proper to proceed in this manner:
Firft find every 100th number, by adding its decimal -264806
&c. verifying them at every roth; then find every 16th num-
ber, by adding continually :002369 &c. which will alfo be
checked and verified at every 25th addition by one of the for-
mer fet of 100, for 25 times. 16 make 4co, ufing a proper pre-
E 2 caution
BS cy Dr. Hut TON’ s Proj A fora
caution to preferve each number true to the neareft unit in the’
6th or laft decimal. Wheres iets
As to the decimals of the numbers in the latter half of the
quadrant, they will be the complements, to 1, of the corre=
{ponding numbers in the firft half; and therefore they may be:
all eafily found by taking each figure from g, and the laft from:
10. But it will be fate to find only every :6thdecimal in this:
way, aud to fillup the intermediate nine by adding, as before,’
the conftant decimal 062648; by which means they — bé
checked and verified at every roth number. |
11. To fill up the third Colunte,| or that of fines, as well as:
thofe of tangents.and fecants, it may firft be obferved, that
the old tables of thofe lines to every mimute, or even to every ten:
feconds of the quadrant, cannot be of fo much ufe as. it'might:
ieem at firft fight; as the very near coincidence of the nume.
bers in the new and old divifions appear very feldom to happen.
i find, indeed, that our arc 1369 anfwers nearly to 45 minutes,
tliat arc excecding 4 45" by only *00632363 or 3, part of a fe-
cond nearly, and fo.in proportion for their equi multiples.’ But
although this degree of coincidence may be-fufficient for check-
ing the correfpanding values of the arcs in the firft-and ‘fecond
columns, we are not thereby authorifed to confider the fine,
tangent, or fecant of 1309 asaccurately equal to that of 45° i
all the feven places of figures, but differing from it by nearly the
\., part of the difference correfponding to 1/’, which:1s about
‘of an unit in the fines and tangents, though next to nothing
in the fecants. This, therefore, although it makes:no fenfible
difference, in this particular cafe, will caufe a difference that
muift not be negleéted in the equi-multiples of 1309 and 45’,
the fines and tangents of which wil differ by half a unit-or
3 more,
new Divifion of the Quadrant, 29
more, and therefore will not be exprefled by the fame number,
but will have fome fmall difference in the feventh or laft figure.
And the fame will happen in almoft all the other arcs; fo that
generally the fines, &c. which are exact for the ares in the
firftcolumn, will not be quite fo for thofe in the fecond, when.
exprefled in whole feconds only, fince thefe will fometimes
differ by the part correfponding to almoit half a fecond. How-
ever, inthis, or any other cafe, where the difference is. exa@lly:
known, we may profitably make ufe of the numbers in the
old tables for conftruéting or verifying thofe of the new, by
taking in the proportional part of the difference. . Let, there-
fore, all the fines, &c. of every 1309. be computed from the
old tables, and entered in the new, by adding to the fine, &c:
of the correfponding multiple of 45’ the like multiple of the
ig part of the proportional difference for 1.° This will give —
about 120 fines, &e. to ferve as a verification of the computa-
tions by the more general methods. But if the fecond column
be exactly conftructed with all its decimal places by the conti-
nual addition of 2:06264807, the old tables may be converted’
into the new, by allowing for the odd feconas and decimals.
And for this purpofe it will, perhaps, be beft to ufe the large
table of RuEericus, which contains the fines, tangents, and
feconds, to ten places of figures for every 10”, and alfo the
differences. At leaft, fuch fines, &c.. may be found in this way
as have their feconds and decimals well adapted for the pur-
pofe; and for fuch as would be found too troublefome in this.
way, recourfe may be had to fome of the following methods..
12. Let, us now examine the expreflions for the fines,’ &cs.
by infinite feries.
‘The-
30 Dr. Hurron’s Projed? for a
The radius being I, and arc a, it is well known that the
i ag 3 Bee See Qo"
fineis =@ — ia +71 — age @! +2 o— so51 ee? &e.
6 8
cofine =I <a fe sg U- =s5 Fe pete an te Ur ee 7 SP soriqes 0” &e.
ane =O te ee ee 1382 git gn
I
EE SE aie re A ML ai dip Nb Reads
cotang.—@ 30 Figs Oe aps aa. ee
+ se Ee) g 4 61 6 een: BON 20 10
feeaht SL ne +O a7 Ot sega ait Waragod GL Ge
2 34 7 3 9 :
cofec. =@ "+50 aset G Seize aT cape” + sq:Tg7o0% &e.
Or the fame faries are thus otherwife exprefled :
_ Bis Spud A ah i ay alg at
fine =a= 5 ae cf i we ET i aitiis eee &ec.
I 2 b c 6 3 e 10
cofine =1+ - @ +——ai— a —— asi ge me:
2 3+4 sin 0 Fino Dia
gid zB
ES rls 17 ae ited 9 ible) ir &c.
tangent = ats a tient ae a +e ° timing a aR rt
cotang. = a— ey, ba akin) | ath eee
3 1S 21 10
fecant =1 + ‘ Bt a? frie OFS 4.13854 a8 4.595728 gro &e,
2 12 150 3416 124651
cofec. =aat*+ 2 a4 al gt 4 BES 5» 1274 oti ?555% 4° &c,
6 60 294 1240 25146
where 4, c, 4, ¢, &c. denote the preceding co-efficients, And
hence, with the help of the table of the firft ten powers of
the firft 100 numbers, in p. 101. of my tables of powers pub-
lifhed by order of the Board of Longitude, may be eafily
found the fines, &c. of all arcs up to 100, by only dividing thofe
powers by their, refpective co-efficients, as alfo of all multiples
of thefe arcs by 10, 100, &c. by only varying the decimal
points in the feveral terms, as the figures will be all the fame:
and
new Divifion of ibe Quadrant. 31
and thus a number of primary fines, &c. may be found, to
check or verify the fame when computed by other methods. By
this method will be found the fines, &c. of the arcs
I, 10, 100, 1000, 19000, 100000;
2, 20, 200, 2000, 20000;
35 30, 300, 3000, 30000 ;
4, 40, 400, 4000, 40000 ;
é&c. till
99 992, 9900, 99000, 990000. ©
13. Again, it is evident, that, of the terms in the feries for
the fine, the firft term ¢ alone will give the fine true to the
neareft unit in the ninth place in the firft 144 fines, or the arc
and fine will be the fame for nine places as. far as the arc 1443
but they will agree to the neareft unit in the feventh place as
far as the arc 669; after which the fecond term of the feries
mutt be included.
‘ 34. When the fecond term is taken in, thefe two terms
a —+ a will give the fines true tothe neareft unit in the ninth
place till the arc becomes 3500. Now the numbers in my
table of cubes (juit publifhed by order of the Board of Longi-
tude) extend to 10000, and therefore all the above cubes are
found in it; confequently taking the fixth part of thofe cubes,
and fubtracting it from the correfponding arcs, the remainders.
will be the fines of thofe arcs, as far as till the are be 3500:
after which the third term of the feries may be taken in, or
other methods may be ufed.
15. But fince, for any arc a, this is a general theorem, wz.
as radius : 2 cof. a:: fin. za: fin.a—1xa+fin.u+1xa; tak-
ing @=1, radius 10000, the fine of 2 will be 1 — oog00000004
and the cofine of @ will be 1000e0-:‘o00005, and the
eel above
a2 Dr. Hurton’s Projeé for a
above proportion will become 100000 : 200000 ~ ‘cooor, or
1120000000001 :: fin.a : fin.m — 1+ fin.n+13 confe-
quently fin. n—-t + fin.n+t is = 2 fin. 2.—ococegdc001
fin.m, and the fines are in arithmetical-progreflion except
only for the fmall difference of -oocogo000r1fin.z, hence
fin.z +1 is = 2—‘0000000001 x fin.z—fin.n —1; and there-
fore taking # fucceffively equal to+1, 2, 3, 4, &c.-the feries
of fines will be as follows:
fin. I = I —'000000000023
fin. 2=2—‘oo000e0001 x fin. 1;
fin. 3 = 2—*oo00000001 » fin. 2=fin. 15
fin. 4=2— ‘000000050! x fin. 3 — fin. 2;
fin. 5 = 2 ~*0000000001 x fin. 4— fin. 3
&&c.
And by this’ theorem, vzz. fin. a+ 1=2-— 0000000001 x fin.
n—{fin.m—1, may be eafily filled up the intervals between
thofe primary numbers mentioned in former articles.
16. In like manner, as radius : 2 cof. a:: cof. 2a@: cof. 2—1 Ya
+ cof.m +1.a3; and hence this theorem, cof. 2+1=
2 ‘0000000001 x caf. m—cof.z—1, by which the cofines
will.be all eafily filled up. And thefe two theorems for the
fines and cofines are fo eafy and accurate, that we need not
have recourfe to any other, but only to check and verify thefe at
certain intervals, as at every 1ooth number, by a proportion from
RHETICUs’s canon, as mentioned at art. 11. or by any other way.
17. The-fines and cofines being compleated, the difference
between the radius and cofine will be the verfed fine; the dif-
ference between radius and fine will be the co-verfed fine; and
thefum of the radius and cofine will be the fup.verfed fine.
13. From
new Divifien of the Quadrant. 33
48. From the fines and cofines alfo, the tangents, cotan-
pents, fecants, and cofecants, may be made by thefe known
proportions, wz. as _
Ks come 2 tadius 3: fine < 2% tangent,
2. fine _- :; radius :: cofine. : cotangent,
a cole, of radius: =: radius. : fecant,
4. fine | FaAdduS 2: Lagius -.- Colecant,
5. radius : fine .:: fecant : tangent,
6. radius : cofine :: cofecant : cotangent,
7. tangent: radius :: radius : cotangent.
Wherefore, the reciprocal of the cofine will be the fecant; the
reciprocal of the fine, the cofecant; the quotient of the fine by
the cofine, the tangent; and the quotient of the cofine by the
fine, the cotangent; or the produé of the fine and fecant will
be the tangent, and the produé of the cofine and cofecant;
the cotangent ; Ory, laftly, the reciprocal of the tangent is the
cotangent ; proper regard being had to the number of decimals,
on account of our radius being 100000 inftead of 1 only.
_ And thefe are to be ufed when the application happens to
be eafier than the general feries, and eafier than a. propor-
tion from RHETICUS’s canon.
But there are other particular theorems, which, by a little
addrefs, may be rendered more coueLio than he of the
former: thus,
19. Tn any two ares this is a general proportion,
As the difference of their fines : |
to the fum of their fines :: : |
fo tangent of half the difference’of the arcs :
to tangent of half their fum.
So that by nie continually the arcs, having the common’.
difference 2, the third term of this proportion will be 1, and:
the fourth term will be found by dividing the fum of the fines
VoL. LXXIV. 7 ae by
a Loos Hutton’ S Projett, ‘&e.
by their difference, which divifor or difference will never con
fift of more than four or five figures, viz. about half the num-
ber of figures that are in the divifors oo in the: pre-
ceding article.
20. Again, As the difference of the cofines : :
to the fum of the cofines ::
fo tangent of half their dizerecet 30
to tangent of half their fam.
And thus the cotangents will be found by dividing the fum of
the cofines of two arcs, differing by 2 zp by their esate difference,
21. Alfo the fecant of an arc is equal to the fum of its tan-
gent and the tangent of half its complement ; ; and the cofe-
cant of an arc is equal to the fum of its cotangent and the tan-
gent of half the arc; or half the fum of the tangent ‘and
cotangent is equal to the cofecant of the double arc. From
whence the fecants and cofecants will be eafily made. 7
22. Thus I have pointed out methods by which the whole
tables may be readily conftructed, Should any other ufeful
methods or improvements occur to any perfon, the communi-
cation of them to me will be thankfully received. ‘I am now
engaged in making fome of the computations ; and it is hoped,
that the facility of them, with the defireablenefs of the tables,
will induce fome ingenious lovers of the mathematics to lend
their aid in performing fome part of the work. Should ‘any
fuch be fo inclined, before he begins, I muft requeft he will be
pleafed to fignify his intention to me, that I may point out to
him fuch parts of the work as have not before been pei formed
or undertaken, to prevent the chance of lofing his labour by
re-computing any parts that may haye been already | executed,
by myfelf or others,
Royal Military Academy f POI LL?
Woolwich, Aug. 12, ree Cuanzes Hurron. :
ohm dh o>
Vil. On she Means off difcovering the Diftance, Magnitude, 8e.
of the Fixed Stars, in confequence of the Diminution of the
. Velocity of ther Light, in cafe fuch a Diminution fhould be
found to take place in any of them, and fuch other Data fhould be
procured from Obfervations, as would be farther necefary for
that Purpofe. By the Rev. John Michell, B. D. F. R.S.
In a Letter to Henry Cavendith, E/y. F.R. S. and A. S.
~ Read November 27, 1783.
DEAR sIR, | Thorshill, May 26, r78ge
HE method, which I mentioned to you when I was laft'
in London, by which it might perhaps be poffible to
find the diftance, magnitude, and weight of fome of the fixed
ftars, by means of the diminution of the velocity of their
light, occurred to me foon after I wrote what is mentioned by
Dr. PrizstLey in his Hiftory of Optics, concerning the di-
minution of the velocity of light in confequence of the attrac-
tion of the fun; but the extreme difficulty, and perhaps im-
poflibility, of procuring the other data neceflary for this pur-
pofe appeared to me to be fuch objections againft the fcheme,
when I firft thought of it, that I gave it then no farther confi-
deration. As fome late obfervations, however, begin to give
us a little more chance of procuring fomeat leaft of thefe data,
I thought it would not be ‘amifs, that aftronomers fhould be
apprized of the method, I propofe (which, as far as I know,
Ez has
36 Mr. Micuey on the Means of difcovering the
has not been fuggefted by any one elfe) left, for want of being
aware of the ufe, which may be made of them, they fhould
neglect to make the proper obfervations, when in their power 3
I fhall therefore beg the favour of: you to prefent the following
RAPER on this fubject to the Royal Society. —
Tam, &c.
THE very great number of ftars that have been difcovered
to be double, triple, &c. particularly by Mr. Herscuet *, if
we apply the doctrine of chances, asI have heretofore done in
my ‘*‘ Enquiry into the probable Parallax, &c. of the Fixed
‘¢ Stars,” publifhed in the Philofophical Tranfaétions for the
year 1767, cannot leave a doubt with any one, who 1s properly
aware of the force of thofe arguments, that by far the greateft
part, if not all of them, are fyftems of ftars fo near to each
other, as probably to be liable to be affected fenfibly by their
mutual gravitation ; and it is therefore not unlikely, that the
periods of the revolutions of fome of thefe about their princi-
pals (the fmaller ones being, upon this hypothefis, to be con-
fidered as {atellites to the others) may fome time or other be
difcovered. hee
2. Now the apparent diameter of any central body, round
which any other body revolves, together with their apparent
diftance from each other, and the periodical time of the revolv-
* See his Catalogue of Stars of this kind, publifhed in the Philofophical Tranf--
actions for the year 1782, which is indeed a moft valuable prefent to the aftrono-
mical world.’ By a happy application of very high magnifyiug powers to his
telefcopes, and by a moft perfevering induftry in obferving, he has made a very
wonderful progrefs in this branch of aftronomy, in which almoft nothing of any
confequence had been done by any one before him,
ing
Diftance, Magnitude, &c. of the Fixed Stars, &c. 34.
ing body being given, the denfity of the central body will be
given likewife. See Sir Isaac Newron’s Prin. b. HI. pr. viit.
cor. I.
3. But the denfity of any central body being given, and the
velocity any other body would acquire by falling towards it
from an infinite height, or, which is the fame thing, the velo-
city of a comet revolving in a parabolic orbit, at its furface,
being given, the quantity of matter, and confequently the
real magnitude of the central body, would be given likewife.
4. Let us now fuppofe the particles of light to be attracted
in the fame manner as all other bodies with which we are ac-
quainted; that is, by forces bearing the fame proportion to
their ws anertie, of which there can be no reafonable doubt,
gravitation being, as far as we know, or have any reafon to.
believe, an univerfal law of nature. Upon this fuppofition
then, if any one of the fixed ftars, whofe denfity was known
by the above-mentioned means, fhould be large enough fenfibly
to affect the velocity of the light iffuing from it, we fhould
have the means of knowing its real magnitude, &c.
5. It has been demonftrated by Sir Isaac Newron, in the
39th propofition of the firft book of his Principia, that if a
right line be drawn, in the direétion of which a body is urged
by any forces whatfoever, and there be erected at right angles
to that line perpendiculars every where proportional to the.
forces at the points, at which they are erected refpectively, the
velocity acquired by a body beginning to move from reft, in;
confequence of being fo urged, will always be proportional to
the fquare root of the area defcribed by the aforefaid perpendi-.-
culars. And hence,
6. If fuch a body, inftead of beginning to move from reft,.
had already fome velocity in the direction of the fame line, .
when,
38s Mr. Micuent onthe Means of difcovering the -
whien it began to be urged by the aforefaid forces, its, velocity .
would then be always proportional to the {quare Foot of the.
fum or difference of the aforefaid area, and another area, whofe
{quare root would ‘be proportional to the velocity which the
body had before it began to be fo urged; that is, to the fquare
root of the fum of thofe areas, if the motion acquired was in.
the fame direction as the former motion, and the fquare root of
the difference, if it was in a contrary direction. See cor. 2. to
the abovefaid propofition.
7. In order to find, by the foregoing propofition, the velo-
city which a body would acquire. by falling towards any other
central body, according to the common law of gravity, let Cin
the figure (tab. III.) reprefent the centre of the central body, to-
wards which the falling body is urged, and let CA bea line drawn
from the point C, extending infinitely towards A. If then the
line RD be fuppofed to reprefent the force, by which the fal-
ling body would be urged at any point D, the velocity which it
would have acquired by falling from an infinite height to the
place D would be the fame as that which it would acquire by
falling from D to C with the force RD, the area of the infi-
nitely extended hyperbolic {pace ADRB, where RD is always
inverfely proportional to the {quare of DC, being equal to the
rectangle RC contained between the lines RD and CD. From
hence we may draw the following corollaries.
8. Cor. 1. The central body DEF remaining the fame, and
confequently the forces at the fame diftances remaining the
fame likewife, the areas of the retangles RC, rC will always
be inverfely as the diftances of the points D, d from C, their
fides RD, rd being inverfely in the duplicate ratio of the fides
CD, Cd: and therefore, becaufe the velocity of a body falling
from an mfinite height towards the pot C, is always in the
fub-.
Diftance, Magnitude, &c. of the Fixed Stars, &c. 39°
fub-duplicate ratio of theilé reCtangles, it will be in the fub-
duplicate ratio of the lines CD, Cd inverfely. Accordingly the
velocities of comets revolving in parabolic orbits are always in
the fub-duplicate ratio of their diftances from the fun in-
verlely ; and the velocities of the planets, at their mean dif-
‘tances (being always in a given ratio to the velocity of fuch
comets, viz. in the fub-duplicate ratio of 1 to 2) mutt neceffa-
rily obferve'the fame law likewule.
g. Cor. 2. The magnitude of the central body remaining
the fame, the velocity of a body falling towards it from an
infinite height will always be, at the fame diftance. from the
point C, taken any where without the central body, in the
dub-duplicate ratio of its denfity ; for in this cafe the diftance
Cd will remain the fame, the line rd only being increafed or
diminithed in the proportion of the denfity, and the rectangle
r€ confequently increafed or diminifhed in the fame proportion.
to.;Cor. 3. The denfity of the central body remaiuing the
fame, the velocity of a body falling towards it from an infinite
height will always be as its femi-diameter, when it arrives at
the fame. proportional diftance from the point Cs for the
weights, at the furfaces of different {pheres of the fame denfity
are as their refpective femi-diameters ; and therefore the fides
RD and CD, or any other fides rd and Ca, which are in a
given ratio to thofe femi-diameters, being both increafed or
diminithed in ‘the fame propertion, the re@angles RC or rC
will be increafed or diminifhed in the duplicate, ratio of the
femi-diameter CD, and — the velogey in the,fimple
ratio of CD.
11. Cor. 4. If the salocitin of a body falling from an ake
height towards different central bodies is the Gunes when it ar-
rives at their furfaces, the denfity of thofe central bodies muft be
4 in
4o | -Mr.Micuent on the Means of diftovering the
“in the duplicate ratio of their femi-diameters inverfely ; for by —
the laft cor. the denfity of the central body remaining the
fame, ‘the rectangle RC will be in the duplicate. ratio of CD;.
in order therefore that the rectangle RC may always remain the
fame, the line RD mutt be inverfely, as CD, and confequently
the denfity inverfely, as the {quare of CD.
12. Cor. 5. Hence the quantity of matter contained in thofe
bodies muft be in the fimpie ratio of their femi-diameters di-
rectly ; for the quantity of matter being always in a ratio com-
pounded of the fimple ratio of the denfity, and the triplicate
ratio of their femi-diameters, if the denfity is in the inverfe
duplicate. ratio of the femi-diameters, this will become the dire@
triplicate and inverfe duplicate, that 1s, when the two are com-
pounded together, the fimple ratio of the femi-diameters,
13. The velocity a body would acquire by falling from an in-
finite height towards the fun, when it arrived at his furface,
being, as has been {aid before in article 3d, the fame with that
of a comet revolving in a parabolic orbit in the fame place,
would be about 20,72 times greater than that ofthe earth in
its orbit at its mean diftance from the fun ; for the mean dif-
tance of the earth from the fun, being about 214,64 of the
fun’s femidiameters, the velocity of fuch a comet would be
greater at that diftance than at the diftance of the earth from
the fun, in the fub-duplicate ratio of 214,64 to 1, and the ve-
locity of the comet being likewife greater than that of planets,
at their mean diftances, in the fub-duplicate ratio of 2 to 13
thefe, when taken together, will make the fub-duplicate ratio :
of 429,28 to1, and the {quare root of 429,28 is 20,72, very: -
nearly.
14. The. 7
Difiance, Magnitude, &c. of the Pixed Stars, Sc. Jas
14. The fame refult would have been obtained by taking the
line RD proportional to the force of gravity at the fun’s fur-
face, and DC equal to his femi-diameter, and from thence
computing a velocity, which fhould be proportional to the
{quare root of the area RC when compared with the f{quare
root of another area, one of whofe fides fhould be proportional
to the force of gravity at the (orgie of the earth; andthe other
fhould be, for inftance, equal, to 16 feet, t inch, the fpace a
body would fall through in one fecond of time, in which cafe
it would acquire a. velocity, of 32 feet, 2 inches per fecond.
Lhe velocity thus found. compared with the velocity of the
earth in its orbit, when computed from the fame elements, ne-
ceffarily, gives the fame refult. I have made ufe of this latter
method of computation upon a, former occafion,. as may be feen
in Dr. PrizstLey’s Hiftory of Optics, p. 787, &c. but I have
rather chofen to take the velocity from that of a comet, in the
article-above, on account of its greater fimplicity, and its more
immediate connexion with the fubject of this ‘paper.
15. The velocity of light, exceeding that of the earth in its
orbit, when at its mean diftance from the fun, .in the propor-
tion,.of about 10.310 10 41),-) 18 we divide 10:310 by 20,72, the
quofient 497, in round numbers, will exprefs the number of
times, which the velocity of light exceeds the velocity a body
~ could acquire by falling. from ant, infinite height towards the
fun, when it arrived at his furface ; and an area whofe fquare
root dhould exceed the {quare root of the;area RC, where RD
is fuppofed to reprefent the force of. gravity at the furface of
the fun, and CD is equal to his femi-diameter, in the fame
proportion, muft confequently exceed the area RC in the pro-
portion of 247.009, the {quare of 497 tor.
Vor Tx wens 16, Hence
x2 Mr. Micuery. on the Means of diftovering the
aE Hence, according to article re, if the femi-diameter of
afphzere of the fame denfity with the fun were to excéed that of
the fun in the proportion of s60 to 1, a body falling from an
§nfinite height towatds it, would have acquired at its furface a
greater velocity than that of light, and confequently, fup-
pofing light to be ‘attracted by ‘the fame force in proportion te
its vis inertiz, with other bodies, all light emitted from fuch/a
body would be made ‘to ‘return towards it, by its own proper
eravity. 7 |
17. But if ‘the femi-diaméter’of a fphere, of the fame: eal
fity with the fun, was of any. other fize lefs than 497 times
that of the fun, though the velocity’of ‘the ‘light emitted from
fuch a body, would never be wholly deftroyed, yet would it
always fuffer fome diminution, more or lefs, according ‘to’the
magnitude of the faid fphres and the quantity of this diminu-
tion may be eafily found in the following manner : Suppofe'S
to teprefent the femi-diameter of the fun, and aS’to ‘réprefent
the femi-drameter of the propofed fphere; then, as appéars
from what has been fhewn before, the fquare ‘root of the dif-
ference between the fquare of 497 S’and the fquare of aS will
be always proportional to the ultimately remaining velocity,
after it has fuffered all the diminution, it can poflibly fuffer
from this caufe; and confequently the difference between the
whole velocity of light, and the remaining velocity, as found
above, will be the diminution of its velocity. And ‘hence the
diminution of ‘the-velocity “of light emitted from the’ fun, on
account of it’s gravitation towards that body, will be fome-
what lefs than a 494.000dth part of ‘the velocity. which it
would have had if no fuch diminution had taken -place; for
the fquare of 497 being 247.009, and the ‘fquare of 1 being 1,
the diminution of the velocity will be the difference between
2 the
“
Diftance, Magnitude, Sc. of the Fixed Stars, ec. 43
the fquare root of 247.009, and the fquare root of 247.008,
which amounts, as above, to fomewhat lefs than one 494.000li
part of the whole quantity.
18. The fame effects would likewife take place, according
to article 11, if the femi-diameters were different from thofe
mentioned in the two laft articles, provided the denfity was
greater or lefS in the duplicate ratio of thofe femi-diameters in-
verfely. |
19. The better to illuftrate this matter, it may not be amifs
to take a particular example. Let us fuppofe then, that it
fhould appear from obfervations made upon fome one of thofe
double ftars above alluded to, that one of the two performed
its revolution round the other in 64 years, and that the central
one was of the fame denfity with the fun, which it muft be,
if its apparent diameter, when feen from the other body, was
the fame as the apparent diameter of the fun would be if feen
from a planet revolving round him in the fame period: let us
further fuppofe, that the velocity of the light of the central
body was found to be lefs than that of the fun; or other ftars
whofe magnitude was not fufficient to affect it fenfibly, in the
proportion of rg to 26. In this cafe theti, according to arti-
cle 17, the {quare root of 247.009 SS muift be to the fquare root
ef the difference between 247.009 SS and aaSS as 20 to 19.
But the fquares of 20 and 19 being 406 and 361, the quantity
247.009 SS muft therefore be to the difference between this
quantity and aaSS in the fame proportion, that is as 247.cog to
222.925,623 and aaSS muft confequently be equal to 24.083,
33 SS, whofe, fquare root 155,2S nearly, or, in round num-
bers, 195 times the diameter of the fun, will be the diameter
of the.central ftar fought. : Me ~
G 2 : 20. Ags
44 Mr. Micuexy on the Means of difcovering the
20. As the {quares of the periodical times of bodies, revolv-
ing round a central body, are always proportional to the cubes
of their mean diftances, the diftance of the two bodies from
each other mutt therefore, upon the foregoing fuppofitions, be
fixteen times greater in proportion to the diameter of the’ central
body, than the diftance of the earth from the fun in proportion
to his diameter; and that diameter being already found to be
alfo greater than that of the fun in the proportion of 155,2 tor,
this diftance will confequently be greater than that of the earth
and fun‘ from each other in the proportion of 16 times 155,2,
that is 2483,2 tor. |
21. Let us farther fuppofe, that from the obfervations, the
greateft diftance of the two ftars in queftion appeared to be
only one fecond;’ we muft then multiply the number 2483,2
by 206.264,8, the number of feconds in the radius of a circle,
and the produét 512.196.7509 will fhew the number of times
which fuch a ftar’s diftance from us muft exceed that of the fun.
The quantity of matter contained in fuch a ftar would be
1§5,2 or 3.738.308 times as much as that contained in the
fun ; its light, fuppofing the fun’s hght to take up 8’. 7”. in
coming to the earth, would, with its common velocity, require
7.900 years to arrive at us, and 395 years more on account of
the diminution of that velocity ; and fuppofing fuch a far to
be equally luminous with the fun, it would {till be very fuf-
ficiently vifible, I apprehend, to the naked eye, notwithftand-
ing its immenfe diftance.
22. In the elements which I have empioyed in the above com-
putations, I have fuppofed the diameter of the central ftar to
have been obferved, in order to afcertain its denfity, which
cannot be known without it; but the diameter of fuch a ftaris
5 much
Difiance, Magnitude, Sc. of the Fised Stars, Ge. 45
much too fmall to be obferved by any telefcopes yet exifting,
or any that it. 1s probably i in the power of human abilities to
make ; ; for the apparent. diameter of the central ftar, if of the
fame denfity with the fun, when feen .from another body,
which would revolve round it in 64 years, would be only the
17i7th part of the diftance of thofe bodies from each othe ef, ¥As
will appear from multiplying 107,32, the number of times the.
fun’s diameter is contained in his pene from:the earth, by 16,
the greater proportional diftance of the revolving body, cor-
re{ponding to 64 years inftead of 1. Now the 1717th part of a
fecond muft be magnified 309.060 times in order to give it an
apparent diameter of three minutes; and three minutes, if the
teleicopes were mathematically perfect, and there was no want
of diftinétnefs in the air, would be but a very tmpall matter to
Judee at *. :
, | fiat F 23. But
* In Mr. Herscuew’s Obfervations upon the Fixed Stars abovementioned, almoft
all of them arereprefented as appearing with a well-defined round dife. That this
is not the real dife, but only an optical appearance, occafioned perhaps by the
conftitution of the eye, when the pencil, by which objeéts are feen, is fo exceed-
ingly {mall as thofe which he employed upon this occafion, is very manifeft, from
the obfervations themfelves, of which indeed Mr. Herscuet feems to be himfelf
fufficiently aware: if it were not fo, the intenfity of the light of thefe flars muft
‘either be exceedingly inferior indeed to that of the fun, or they muft be immenfely
larger, otherwife they muft have a very fenfible parallax; for ‘the fun, if removed
to 10.000.000 times his prefent diftance, would ftill, I apprehend, be of about
the brightnefs of the ftars of the fixth magnitude; in which cafe he muft be mag-
nified 1.000.000 times to make his apparent dife of any fenfible magnitude; or,
on the other hand, if he was only removed to a thoufandth part of that diftance,
then he muft be lefs luminous in the proportion of 1.c0o0,000 to I, to make him
appear no brighter than a ftar of the fixth magnitude. Now the fun’s diameter
being contained nearly 215 times in the diameter of the earth’s orbit, the annual
parallax therefore of fuch a body in that cafe, if it was placed in the pole of tne
; ecliptic,
46 Mr. Micuexr on the Means of difeovering the
23. But though there is not the leaft probability that this
element, fo eflential to be known, in order to determine with
precifion the exact diftance and magnitude of a ftar, can wer 6b
obtained, where it is in the fame circumftances, or nearly the
fame, with thofe above fuppofed, yet the other elements, fuch
as perhaps may be obtained, are fufficient to determine the dif-
tance, &c. with a goad deal of probability, within {ome mode-
ate limits; for in whatever ratio the real diftance of the two
ftars may be greater or lefs than the diftance fuppofed, the den-
fity of the central {tar muft be greater or lefs in the fixth
power of that ratio inverfely ; for the periodic time of the re-
volving body being given, the quantity of matter contained in
the central body muft be as the cube of their diftance from each
other. See Sir I. Newron’s Prin. b. 3d. pr. 8th. cor 3d. But
the quantity of matter in different bodies, at whofe furfaces the
velocity acquired by falling from an infinite height is the fame,
muft be, according to art.12, dire€tly as their femi-diameters ;
the femi-diameters therefore of {uch bodies muft be in the tri-
plicate ratio of the diftance of the revolving body ; and confe-
quently their denfities, by art. 11, being in the inverfe dupli-
cate ratio of their femi-diameters, muft be in the inverfe fex-
tuplicate ratio of the diftance of the revolving body. Hence
if the real diftance fhould be greater or lefs than that fuppofed,
an the proportion of two or three to one, the denfity of the cen-
tral body muft be lefs or greater, in the firft cafe, in the pro~
portion of 64, or in the latter of 729 to 1.
ecliptic, would be 215 times its apparent diametcr ; and as the bright ftar in
Lyra appeared to Mr. Herscuer about a third part of a fecond in diameter, if this
was its real difc, and it was no bigger than the fun, it would confequently have
sn @nnual parallax in-the pole of the ecliptic of about 72’.
24. There
Diftance, Magnitude, Ce. of the Fixed Stars, Cc. 47
24. There is alfo another circumftance, from which perhaps:
fome little additional probability might be derived, with regard
to the real diftance of a ftar, {och as that we have fuppofed ;
but upon which however, it muft be acknowledged, that no
great ftrefs can be laid, unlefs we had fome better analogy to go
upon than we have at prefent. The circumftance I mean is the
greater fpecific brightnefs which fuch a ftar muft have, in pro-
portion as the real diftance is lefs than that fuppofed, and vice
versa ; fince, in order that the ftar may appear equally luminous,
its {pecifie brightnefs muft be as the fourth power of its diftance
inverfely ; for the diameter of the central ftar being as the
cube ‘of the diftance between that and ‘the revolving ftar, and
their diftance from the earth being in the fimple ratio of their
diftance from each other, the apparent diameter of the central
-ftar mutt be as the {quare ‘of its real diftance from the earth,
and confequently, the furface of a {phere being as the {quare of
its diameter, the area of the apparent ‘dife of fuch a. ftar muft
be as the fourth power Of ‘its diftahce from the earth; ‘but in
whatever ratio the apparent dife of the ftar is greater or lefs,.
in the fame ratio inverfely muft bé the intenfity of its light,.
in order to make it appear equally luminous. Hence, if its real”
diftance fhould be greater or lefs than that fuppofed in the pro-
portion’ of 2 or 3 to r, the intenfity of its light muft be lefs or
greater, in the ‘icf cale, in the proportion of 16,’ er, ‘in ‘the:
latter of 81 to t.
25. According to Monf. Boucuer (fee his Traité d’Optique)
the brightnefs of the fun exceeds that of a wax candle in no
lefs a proportion than that of 8009 to 1. If therefore the bright-
nefs of any of the fixed ftars fhould not’ exceed that of our com-
mon candles, which, as being fomething -lefs luminous than.
WAX,,
45 Mr. Micuexny on the Means of difcovering the
wax, we will fuppofe in round numbers to be only one
io.coodth part as bright as the fun, fuch a ftar would not be
vifible at more than an 100dth part of the diftance, at which
it would be vifible, if it was as bright as the fun. Now be-
ccaufe the fun would fill appear, I apprehend, as luminous, as
the ftar Sirius, when removed to 409.coo times his prefent
diftance, fuch a body, if no brighter than our common candles,
would only appear equally luminous with that ftar at ‘4000
times the diftance of the fun, and we might then begin to be
able, with the beft telefcopes, to diftinguith fome. fenfible ap-
parent diameter of it; but the apparent diameters of the flars
of the lefs magnitudes would ftill be too fmall to be diftinguifh-
able even, with our belt telefcopes, unlefs they were yet a good
deal lefs luminous, which may. poffibly however be the cafe
with fome of them; for, though we have indeed very flight
grounds to go upon with regard to the fpecific brightnefs of the
fixed {tars compared with that of the fun at prefent, and can.
therefore only form very uncertain and random conjectures
concerning it, yet from the infinite variety which we find in
the works of the creation, it is not unreafonable to fufpect,
that very poffibly fome of the fixed ftars may have fo little na-
tural brightnets in proportion to their magnitude, as to admit
of their diameters having fome fenfible apparent fize, when
they fhall come to be more carefully examined, and with larger
and better telefcopes than have been hitherto in common ufe.
26. With regard to the fun, we know that his whole fur-
face 1s extremely luminous, a very fmall and temporary inter-
ruption fometimes from a few {pots only excepted. This uni-
verfal and exceflive brightnefs of the whole furface is prcbably
owing to an atmofphare, which being luminous throughout,
and
Diftance, Magnitude, Gc. of the Fixed Stars, Bc. yg
and in fome meafure alfo tranfparent, the light, proceeding
from a confiderable depth of it, all arrives at the eye;. in the
fame manner as the light of a great number of candles would
do, if they were placed one behind another, and their flames
were fufficiently tranfparent to permit the light of the more
diftant ones to pafs through ve that were nearer, without
any interruption. |
27. How far the fame conftitution may take place in the
fixed ftars we don’t know; probably however it may do fo in
many ; but there are fome appearances with regard to a few of
them, which feem to make it probable, that it does not do fo
univerfally. Now, if Iam right in fuppofing the light of
the fun to proceed from a luminous atmofphere, which muft
neceflarily diffufe itfelf equally over the whole furface, and I
think there can be very little doubt that this is really the cafe,
this conftitution cannot well take place in thofe ftars, which
are in fome degree periodically more and lefs luminous, fuch
as that in Collo Ceti, &c. It is alfo not very improbable, that
there is fome difference from that of the fun, in the conftitution
of thofe ftars, which have fometimes appeared and fometimes
difappeared, of which that in the conftellation of Caffiopeia is a
notable inftance. And if thofe conjectures are well founded
which have been formed by fome philofophers concerning ftars
of thefe kinds, that they are not wholly luminous, or at leaft
not conftantly fo, but that all, or by far the greateft part of
their furfaces is fubje&t to confiderable changes, fometimes be-
coming luminous, and at other times being extinguifhed; it is
amonegft the ftars of this fort, that we are moft likely to meet
with inftances of a fenfible apparent diameter, their light being
much more likely not to be fo great in proportion as that of
the fun, which, if removed to four hundred thoufand times
WoL. LXXIV. H his
50 Mr, Micuets on the Means of ai ifeavering the.
his. prefent diftance would ftill appear, I apprehend, as bright as.
S11Us, as I have obferved above ; whereas it is hardly to be ex-
pected, with any telefcopes whatfoever, that we fhould ever be.
able to diftinguifh a well defined dife of any body of the fame
fize with the fun at much more than ten thoufand times his,
diftance. . : bik sah se ‘ oa f,
28. Hence the greateft diftauce at which it would be poffible.
to diftinguith any, fenfible apparent diameter of a body as denfe
as the fun cannot well greatly exceed five hundred times tem,
thoufand, that is, five million times the diftance of the fun 3,
for if the diameter of fuch a, body was not lefs than five hun-.
dred times that of the fun, its ight, as has been fhewn above,,
i art. 16; could never arrive at us,..; 7
29. If there fhould really exitt, in aa aaie any, bodies; . whofe.
denfity is not lefs than that.of the fan, and whofe diameters are.
more than 500 times the diameter of the fun, fince their
hight could not arrive at us; or if there fhould exit any other
bodies of a fomewhat {maller fize, which are not naturally lu-
minous; of the exiftence of bodies under either of thefe cir-
cumftances, we could have no information from fight ; yet, if,
any other luminous bodies fhould happen to revolve about thems
we might ftill perhaps from the motions of thefe revolving
bodies inter the exiftence of the central ones with fome degree
of probability, as this might afford a clue tofome of the ap-
parent irregularities of the revolving bodies, which would not
be eafily explicable on any other hypothefiss; but as the con-.
fequences. of fuch a fuppofition are very obvious, and, the
confideration of them fomewhat befide my, prefent purpofe, I
fhall not profecute them any farther. )
a : 30. The
Diftance, Magnitude, &c. of the Fixed Stars, 8c. st
"30. The diminution of the velocity of light, in cafe it
fhould be found to take place in any of the fixed flars, is the
principal phenomenon whence it is propofed to difcover their
diftance, &c. Now the means by which we may find what
this diminution amounts to, feems to be fupplied by the dif-
ference which would be occafioned in confequence of it, in the
refrangibility of the light, whofe velocity fhould be fo dimi-
minifhed. For let us fuppofe with Sir Isaac Newtown (fee
his Optics, prop. vi. paragr. 4 and 5) that the refraction
of light is occafioned by a certain force impelling it to-
wards the refraéting medium, an hypothefis which perfee-
ly accounts for all the appearances. Upon this hypothefis
the velocity of light in any medium, in whatever direétion it
falls upon it, will always bear a given ratio to the velocity it
had before it fell upon it, and the fines of incidence and re-
fraction will, in confequence of this, bear the fame ratio to
each other with thefe velocities inverfely. Thus, according to
this hypothefis, if the fines of the angles of incidence and
refraction, when light pafles out of air into glafs, are in the
ratio of 31 to 20, the velocity of light in the glafs muft be to
its velocity in air in the fame proportion of 31 to20. But be-
caufe the areas, reprefenting the forces generating thefe veloci-
tics, are as the {quares of the velocities, fee art. 5. and 6. thefe
areas muft be to each other as g61 to goo. And if 400 tepre-
fents the area which cor refponds to the force producing the ori+
ginal velocity of light, 561, the difference between 961 and
400, muft reprefent the area correfponding to the additional
force, by which the light was ielielae at the furface of the
glafs.
5 31. In art. 19. we fuppofed, by way of example, the velo-
city of the light of fome particular ftar to be diminifhed in the’
Hig ratio
52 Mr. MicuEvuy on the Means of difcovering the
ratio of 19 to 20, and it was there obferved, that the area re- |
prefenting the remaining force which would be neceflary to
generate the velocity 19, was therefore properly reprefented by
2$-dth parts of the area, that fhould reprefent the force that
would be neceffary to generate the whole velocity of light,
when undiminifhed. If then we add 561, the area reprefent-
ing the force by which the light is accelerated at the furface of
the glafs, to 361, the area reprefenting the force which would
have generated the diminifhed velocity of the ftar’s light, the
{quare root of g22, their fum, will reprefent the velocity of
the light with the diminithed velocity, after it has entered the
glafs, And the fquare root of 922 being 30,364, the fines of
incidence and refraction of fuch light out of air into glafs will
confequently be as 30,364 to 19, or what is equal to it, as
31,96 to 20 inftead of 31 to 20, the ratio of the fines of inci-
dence and refraction, when the light enters the glafs with its
velocity undiminifhed.
32. From hence a prifm, with a fmall refracting angle,
might perhaps be found to be no very inconvenient inftrument
for this purpofe: for by fuch a prifm, whofe refracting angle
was of one minute, for inftance, the light with its velocity
undiminifhed would be turned out of its way 33’, and with
the diminifhed velocity 35”, 88 nearly, the difference between
which being almoft 2”. 5 3’”, would be the quantity by which
the light, whofe velocity was diminifhed, would be turned out.
of its way more than that whofe velocity was undiminifhed.
33- Let us now be fuppofed to make ufe of fuch a prifm to
look at two ftars, under the fame circumftances as. the two ftars.
in the example above-mentioned, the central one of which
fhould be large enough to diminifh the velocity of its light one
twentieth part, whilft the velocity of the light of the other,
which
Diftance, Magnitude, &c. of the Fixed Stars, &c. 53
which was fuppofed to revolve about it as a fatellite, for want
of fufficient magnitude in the body from whence it was emit-
ted, fhould fuffer no fenfible diminution at all. Placing then
the line, in which the two faces of the prifm would interfe&
each other, at right angles to a line joining the two ftars; if
the thinner part of the prifm lay towards the fame point of the
heavens with the central ftar, whofe light would be moft turned
out of its way, the apparent diftance of the ftars. would be in-
creafed 2”. 53’”’ and confequently become 3”. 53’” inftead of 1”,
only, the apparent diftance fuppofed above in art. 21. On the
contrary, if the prifm fhould be turned half way round, and
its thinner part lye towards the fame point of the heavens with
the revolving flar, their diftance muft be diminifhed by a like
quantity, and the central ftar therefore would appear 1”, 5 3’”’ dif-
tant from the other on the oppofite fide of it, having been removed
from its place near three times the. whole diftance between them.
34. Asa prifm might be made ufe of for this purpofe, which
fhould have a much larger refracting angle than that we have
propofed, efpecially if it was conftructed in the achromatic
way, according to Mr. poLLonp’s principles, not only fuch a
diminution, as one part in twenty, might be made ftill more
diftinguithable; but we might probably be able to difcover ,
confiderably lefs diminutions in the velocity of light, as. per-
haps a hundredth, a two-hundredth, a five-hundredth,. or everx
a thoufandth part of the whole, which, according to what
has been faid above, would be occafioned by {pheres, whoie
diameters fhould be to that of the fun, provided they were of
the fame denfity, in the feveral proportions nearly of 70, 50,
30, and 22 tor re{pectively.
35. If fuch a diminution of the velocity of light, as that
above fuppofed, fhould be found really to take place, in confe-
qence
54. Mr. Mocnevz on the Means of difeovering the.
quence of its gravitation towards the bodies from whence it i
emitted and’ there fhould be feveral of the fixed tars large
enough to make it fufficiently fenfible, a {et of obfervations
upon this fubject might probably give us fome confiderable in-
formation with regard to many circumftances of that part of
the univerfe, whichis vifible to us. The quantity of matter
contained in many’ of the fixed ftars might from hence be judged
of, with a great degree of probability, within fome moderate
limits; for though the exa& quantity muft fill depend upon
their denfity, yet we muft fuppofe the denfity moft enormoutfly
different from that of the fun, and more fo, indeed, than one
can eafily conceive to take place in fact, to make the error of
the fuppofed quantity of matter very wide of the truth, fince
the denfity, as has been fhewn above in art. 11. and 12. which
is neceflary to produce the fame diminution in the velocity of
light, emitted from different bodies, is as the fquare of the
quantity of matter contained in thofe bodies inverfely.
36. But though we might poffibly from hence form fome
reafonable guefs at the quantity of matter contained in feveral
of the fixed ftars; yet, if they have no luminous fatellites
revolving about them, we fhall ftill be at a lofs to form any
probable judgment of their diftance, unlefs we had fome ana-~
log'y to go upon for their fpecific brightnefs, or had fome other
means of difcovering it; there is, however, a cafe that may
poftibly occur, which may tend to throw fome light upon this
matter.
37. have fhewn in my Enguiry into the probable Parallax,
&c. of the Fixed Stars, publifhed in the Philofophical ‘Tranf-
actions for the year 1767, the extremely great probability there
is, that many of the fixed ftars ‘are colleCted together into
groups; and that the Pleiades’ in “patticular’ ‘conftitute one of
thefe
Difiance, Magnitude, &c. of the Fixed Stars, &c. 55
thefe groups. Now. of the ars which we.there fee collected
together, it is highly probable, as I have obferved in that paper,
that there is not one in.a hundred which does not belong to the
group itfelf; and by far the greateft part, therefore, according
to the fame idea, muft lye within a {phere, a great circle of
which is of the fame fize with a circle, which appears\to. us.
to mcelude the whole. group.. If we fuppofe,. therefore, this.
ivcle.to be about: 2”.. in diameter, and confequently only about
a sc aa part of the diftance at which it is feen, we may
conclude, with the higheft degree of probability, that by. far
the greateft part of thefe ftars do. not ‘differ in their diftances
from. the fun. by more,than about one part in. thirty, and- from
thence deduce a fort of {cale of the. proportion. of the light
which is produced by different, ftars. of the fame group or fyftem
in the Pleiades at leaft; and, by a fomewhat probable analogy,,:
we may do the fame, in other fyftems likewife. But. having:
yet, no means; of. knowing their real. diftance, or {pecific bright-
ne{s, when compared either with the fun, or’ with one another,..
we fhall fill, want ididiasibhas more to. form: a. ofenihet neers
from.
38 1 a Rei it fieuld ; be. found,, that Sak ree
Pleiades, or any other like fyftem, cheseare fome ftars chat are:
double, triple, &c. of which oneis a larger central body,. with
one or more fatellites revolving about it, and the central body
fhould likewife be found to diminifh the velocity of its. light ;::
and more efpecially, if there: fhould be feveral fuch inftances
met with in the fame fy{tern ;, we fhould then begin to have a
kind of, meafure-both of the diftance of fuch a fyftem of ftars.
from the earth, and of their mutual diftances from each other..
And if feveral inftances of this kind fhould occur in different
groups or fyftems of ftars, we might alfo, perhaps, begin to
x form
56 Mr. Micuen on the Means of difcovering the
form fome probable conjectures concerning the fpecific denfity
and brightnefs of the ftars themfelves, efpecially if there
fhould be found any general analogy between the quantity of
the‘diminution of the light and the diftance of the fyftem de-.
duced from it; as, for inftance, if thofe ftars, which had the
greateft effect in diminifhing the velocity of light fhould in
general give a greater diftance to the fyftem, when fuppofed to
be of the fame denfity with the fun, we might then naturally
conclude from thence, that they are lefs in bulk, and of-
greater fpecific denfity, than thofe ftars which diminifh the ve-
locity of light lefs, and vice verfé. In like manner, if the
larger ftars were to give us in general a greater or lefs quan-
tity of light in proportion to their bulk, this would give us a
kind of analogy, from whence we might perhaps form fome
judgment of the fpecific brightnefs of the ftars in generals.
but, at all adventures, we fhould have a pretty tolerable mea-
fure of the comparative brightnefs of the fun and thofe ftars,
upon which fuch obfervations fhould be made, if the refult of
them fhould tur out agreeable to the ideas above explained.
39. Though it is not improbable, that a few years may in-
form us, that fome of the great number of double, triple ftars,
&c. which have been obferved by Mr. HerscuEL, are fyftems
of bodies revolving about each other, efpecially if a few more
obfervers, equally ingenious and induftrious with himfelf could
be found to fecond his labours; yet the very great diftance at
which it is ‘not unlikely many of the fecondary ftars may be
placed from their principals, and the confequently very long
periods of their revolutions *, leave very little room to hope
! that
* If the fun, when removed to 10,000.000 times his prefent diflance, would
fill appear as bright as. a ftar of the fixth magnitude, which I apprehend to be
pretty
Diftance, Magnitude, &c. of ibe Fixed Stars, &c. 57
that any very great progrefs can be made in this fubject for
many years, or perhaps fome ages to come; the above outlines,
therefore, of the ufe that may be made of the obférvations
upon ‘the double ftars, &c. provided the particles of light
fhould be fubjeé& to the fame law of gravitation with other
bodies, as in all probability they are, and provided alfo that
fome of the ftars fhould be large enough fenfibly to diminith
their velocity, will, I hope, be an inducement to thofe, who
may have it in their power, to make thefe obfervations for the
benefit of future generations at leaft, how little advantage
foever we may expect from them ourfelves; and yet very pof-
fibly fome obfervations of this fort, and fuch as may be made
in afew years, may not only be fufficient to do fomething, even
at prefent, but alfo to fhew, that much more may be done
hereafter, when thefe obfervations fhall become more numerous,
and have been continued for a longer period of years.
pretty near the truth, any fatellire revolving -round fuch a ftar, provided ‘the ftar
was not either of lefs fpecific brightnefs, or of greater denfity than the fun,
muft, if it appeared at its greateft elongation, at the diftance of one fecond only
from its principal, be between three and four hundred years in performing one
revolution; and the time of the revolution of the very {mall ftar near « Lyre, if
it is a fatellite to this latter, and its principal is of the fame {pecific brightnefs and
denfity with the fun, could hardly be lefs than eight hundred years, though 37’
the diftance at which it is placed from it, according to Mr. Herscuer’s obfer-
vations, fhould happen to be its greateft diftance. Thefe periodical times,
however, are computed from the above diftances, upon the fuppofition of the
ftar, that revolves as a fatellite, being very much {maller than the central one, fo
as not to-difturb its place fenfibly; for if the two ftars fhould contain equal, or
nearly equal, quantities of matter, the periodical times might be fomewhat lefs, on
account of their revolving about their common centre of gravity, in circles of
little more than half as great a diameter as that in which the fatellite muft revolve
upon the other fuppofition,
VoL. LXXIV. I ’
(5803 A.
J
VIL A Meicorelogical Fournal for the Year 1782, kept at
Minehead, ze Somerfetfhire. By Mr. John Atkins 5. com
municated by Sir Jofeph Banks, Bart. P. R. §,
Read January 15, 1784.
Bad: ie Minehead, March 27, 1783.
rE NHE numberiefs philofophical difcoveries and meteorolo-
gical journals which I find have been addrefled to you,
as being a gentleman whole great abilities have raifed you to
the higheft pitch of grandeur in the philofophical world, and
which, I find, have been treated with the greateft candour and
refpect, and publifhed under your diretion for the improvement
of {cientific knowledge, make me prefume (though an unknown,
and even unheard of, individual) to direct this journal to you, not
boafting, but rather doubting, of its being worthy of your recep-
tion ; but my having found fo great a difference between the laft
year and feveral preceding years, in the variations of the atmo-
iphere, both barometrical and thermometrical, induced me to.
communicate it to other obfervers through your approbation.
Tam, &c.
3 oe THE
Lhilos.Trans.Vol LXXIV.Tab W, /2. 38.
Lhulos Trans Vol LXXIV. Tab WM. /9. 68.
con.
er Sera 7
Mr, Arxins’s Meteorological Fournal, 8c. 59
‘THE inftruments are kept at a houfe about thirty feet above
high water in the Briftol Channel. ‘The barometer is made after
-pe Luc’s methed; and to obferve the moft minute alteration I
have divided it into the one-fixteenth of a line, or 192 partsin an
inch. The thermometer is a mercurial one, eraduated according
to FAHRENHEIT'S {cale, as being the moft univerlal, though, I
think, a partial one, and placed in the open air in a northern
afpect. An hygrometer I have likewife kept in the open air ;
but being an inftrument that does not admit of, as I ever heard
of, a certain bafis, whereon to fix the fundamental point be-
tween. the greateft moifture and yvreateft drought, and there-
fore of little ufe to diftant obfervers, I have omitted thefe ob-
fervations. For the eafe of correfpondent obfervers, I have
drawn two columns of the barometer; the firft divided inte
192d parts of an inch; the fecond into rooth parts. The
figures in the column of winds denote its ftrength from 9 to
go degrees of a quadrant. And the moft prevailing winds are
from north to weft, being generally in thofe dire@ions two-
thirds of the year, occafioned, as 1 imagine, by the indraughe
of the Briftol Channel. The barometer this year has taken a
greater range than ever I found thefe feveral years, being 2.44
inches. ‘The thermometer hkewife from 21° to 81°; and the
three rainy months of Odtober, November, and December,
there fell very little more rain than fell in the month of Au-
guft alone, which is very uncommon in this part of the king-
dom. On the ninth of February an odd phenomenon appeared
to me about ro miles from hence, on my journey to Tiverton.
I obferved an halo, exactly fimilar to that of the fun, the cen-
ter of the arch about 15° high, and both ends terminated in a
field of fuow; but as rainbows are feen only with the fun behind
one’s back, this, on the contrary, was between me and the fun.
I 2 January
¢
60 Mr. ATKINS’s Metroid ai ‘
Jenvary 1782.
¢)
S Pad Barom./Barom.
Winds. |Clouds.| 192 | 100
parts. | parts.
Inches. |Inches.
(SME 2s 29. 96| 29.50 50.
Weather. |
Hour.
| Thermom
1|12 : 29.100| 29.52 152)
9 Ww 20 29-104) 29.54 | 50
8 {Rain Ww 30 29. 16) 29. 9 148
2\12 29-120 29.63 |s5o
9 29.128) 29.67 150
8 | Fair. WNW 35 29.120] 29.63 |48
3|12|Some fhowers 29.140) 29.73 |50
9 29.152) 29.79 148}
a ee |
WNW 10 29.160] 29.84 |50:
29-149} 29-73 | 54
29.128] 29.07 |49
a rr | ee
8 |Showers. WNW 27 2.9.132| 29.69 | 50
5|12
29-150] 29.78 |51
9 29.170| 29.89 |50
8 |Fair. WNW 22 29.184] 29.94 |46
6| 12 |Cloudy. : 30. O} 30. O | 50
9 BO. 0) 3 © 149.
8 |}Hard thowers. NW 40 29-112) 29.59 145
7} 12 29.120| 29.63 |50
g|Stormy, hail fhowers, 70 29.128] 29.67 |42
8 | Fair. WSW 20 29.158| 29.83 |44
8} 12 |Showers. 29.150] 29.78 | 50
9 29.128] 29 67 |48
8| Rain, S 40 29. 0} 29. 0 |§0
9) 12 WNW 50 28.168} 28.88 |40
9} Very flormy. Nw _ 80 29+ 40] 29.21 |38
4. January
“
| Rept at Minehead, in Somerfetthire,
29.144) 29.75 |45
61
January 1782.
=| ae :
= Weather. Winds. |Clouds.| 192 {too | 5 Rain
parts. | parts. ay
“4 ‘ Inches. |Inches. ‘ Inch
8) Very ftormy. NWbyW 80 29.128 | 29.67 | 37
19 29.189] 29.94 |40/0-49
g| Freezing hard. 30. 48) 30.25 | 35
ieiard foot tard fair. NW o 30. 48] 30.25 lag
12 30. 48) 30.25 | 29
9 30. 48] 30.25 135
8 | Foggy rain. NW “tony: 30. 40} 20.21 145
II 30. 40} 30.21 | 48
9 30. 64) 30.33 149
8 | Cloudy. WNW o 3°. 7° 30. 37° haan
12| Foggy rain. 3% 12). 30-37 | 5k
9 39 07) 39-35 |50
8} Fair, Sby W 15 30. 56] 30.29 |45
12 20. 40) 30.21 50
9 30. 24/ 30.13 | 4a
8 |Frofty, but foggy. NNW 35 | 30. 20| 30.11 |40
12 30. 28] 30.15 |44
9 30. 16] 30. 9 | 44
8 |Small rain. WNW 10 29.128 29.07 |47
12] 29.106} 29.55 | 50
g|Stormy, hail fhowers, NW 75 29. 80] 29.42 142
${Stormy, but dry, NW .. 70 29. 88] 29.46 | 3
12 29. 96| 2q50 |43
9 AO TL 2) 20-59 NS
8 |Fair. SW . 20 29.118] 29.61 |48
18|12|Some fmall rain, 29.126} 29.66 |48
January
p
62 Mr, Arxins’s Meteorological Fournal
January 1782.
°
Winds. |Clouds,
| Thermom
a
8 f Fair, with hard winds,
L but very mild,
WNW 60
Nw 60
70
N byW 60
29. 48] 29.25
75
January
¥
a
kept at Minehead, zz Somerfetthire. 63
January 1782.
. 8arom. |Barom, |
| 2 Weather, Winds. |Clouds.| 192 | 100 | 8
ais parts. | parts. |
CTE SEEE GSREEESATTEE? GEENSEETTS GRESSTESTEGSGEEEENTS | GETS eae
Inches. |Inches.
—
31
8|Stormy, fhowers.
12
8 |Fair and cold.
12|Fair.
5
g|Cloudy.
Cloudy, but fnow onl,,
811 “neditant hill, INE
12|Fair.
g|Freezing hard,
8|Froft.
2
9
9|Calmer, with hail in the night,
ees
NWbyW 80
20
WwW 20
NW
SW
NE SW
a
29. 321 29.17 |40
29+ 10) 29. 9145
29. 16/29. 9 |40
28.176) 28.92 |33
28.160] 28.84 |41
28.154] 28.81
29. Of 29. O 137
ee ef ee ee |
29. 64) 29.34 137
29.112] 29.59 |40
29.168) 29.88 | 35
30. 16) 30. 9 133
30., 16}; 203/94 1\97
30. 16} 30 9 132
February
- Total rain 3-94
“Od.
Mr, Arains’s Meteorological Fournal
February 1782. .
Winds.
7| Very hard froft. Ww
t}12/ Farr. SW 20
9 Sleet.
7 Rain SW 30
2112
9 Fair,
7 | Froft Sby E 20
gi 12 Sleet SW
9
] Fair Ww Oo
4}12
9 Snow on the hilts. NE 20
7 Cloudy day. Ne 40
iS 12
9
7|Fair, froft. NE 20
6112
9 W oO
7\Fair, hard froft. W O
oi I2
NE 10
7| Fair, froft.
9
{ Fair, very hard froft; an|.,
7 extraordinary halo. te <8
M12 Cloudy.
9
Barom. {Barom.
192
parts.
Clouds.
| parts.
Inches, -
Sole
2.9.04
29.34
29.68
29.63
20-59
29.50
29.44
2.9.4.2
29-42
29.46:
29.31
29. 6
2g.11
29.50
29-73
29.84.
29.88
| Phermom.
—
inches.
20.10
29.180
29.160
29.130
29-120
20.012
29. 96
29. 54
29. 80
29. 80
29. 88
29. 60
oro i)
29. 20
29. 96
29.140
29.160
29.168
29.180} 29.94 |34
29.180] 29.94 |37
29.186] 29.97 133
29.182] 29.95 |27
29.180] 29.94 133
29.180] 29.94 |33
February
kept af Minehead, i Somcrfetthire, 6s
February 1782.
ane mee
} ot A
KE sate comenede | = |
tr Weather. | Winds. jClouds.j}/ ig2 | 100 | 5 {Rain.
parts. | parts. ai
Inches. Inches. | 5{ Lach.
7{Cloudy, hard froft. NB ad 1 29.180] 29.94 | 291
12}Yair. | 29.180} 29.94 135
9 99.180! 29.94 136) |. |
| 7\Pair, hard frof. ENE 20 29.184! 29.96 |30
12 29.168] 29.88 } 325
9| Cloudy. 55 29.160) 29.84 | 34
7\Cloudy, hard froft. |E 50 129.170] 29.89 131
12| Fair. 29.186| 29.97 | 33
9 |Cloudy. 320. o| 30 O26
7 \Fair, very hard frott. WNW 10] NE 30. 7 20.22 1217 |
12 |Cloudy. NW 29.184] 29.96 | 38
9 N NNE | 29.184] 29.96 | 36
7 |\Cloudy, froft. j E 20 129.176] 29.92 | 36
12 |Thawing, ‘| 29.180] 29.94 }40] -
) 29.184) 29.94 |37
7 |Cloudy, TB: 10 129.184} 29 96 |37
12 |Sleet. 430. Cl) 30. (0) 138
g|Fair, freezing- 60 | 30. 30 30.16 | 32
7 |Exceflive froft, oe 30 30. 40] 30 21 log
16; 12. Fair. 130. 40| 30-21 128
ZO. 40} 30.21 | 30 |
9 |Cloudy.
ee ee | eee
| 20. 50) 20.20 | 44
20. 50) 30.20° | 46
30. §0| 30 26 | 32,
7,;Cloudy andthawing. | |ENE 15
g|Fair, freezing.
ef ee Ree | eee
7\ Fair, exceffive froft, _{W Gy i 3- 64] 30.33 | 21
118/12 Much milder. S 30 64] 30.33.1397
g} Cloudy. SE 30. 60] 30.31 | 37
V.o1,; LXXIY. Kk February
66 Mr, AT «INS’s Meteorological Fournal
February 1732.
Barom. |Barom.,
Clouds. | 192 100
parts. | parts.
ate ! :
— Weather. © Winds,
aad, - ‘
| Thermom,
_ Se
Inches. {Inches
» | Cloudy, a little froft. E 10 30. 60} 30.31 135]
12 30. 57] 30.2030
1.9 # 30+ 48} 30.25 13
a: Cloudy. W TO 30. 40} 30.21 ''|34
12 30. 40] 30.21 139
9|. . WNW 29-180] 29.94 137
b Fair. , SbyW o 29.166| 29.84 !}2
IB |= 1 ¢ 29-144) 29.75 |41
g|Rain. 29+ 32]/29.17 |40
“| Fair, W 20 29. 48}29.25 41
12 29. 401 29.21 144
9 Cloudy. A 29. 32 29.17 40
be Hard rain and wind. S 80 29. °%01'29. oO Nae
12 23.168] 28.88 49
4 28.160] 28.84
9 WNW 40 ~1 28-170} 28.89" 146
4.) Fair. WNW 30 29. 30] 29.16 |45
12 29:100} 29.52 |47
| Rain in the night. 29.168} 29.88 {40
7|Fair. W by N35 29.172] 29.90 [45
12
9
| Small fhowers. Ww WS 29.186] 29.97 {48
12| Fair and mild. 30/590! 20. O' 1On
9 30. Ol 30. OT ia
4| Cloudy. S 5 29.180] 29.94 |50
12 29.180] 29.94 |§2
of Fair . 29-184] 29.96 |45
February
kept at Minehead, 7# Somerfetthire. 67
February 1782.
Barom, |Barom.
Clouds.} 192 100
parts. | parts.
*
Weather. Winds,
| Thermoin,
rs)
p
5
Inches. {Inches, | ,jInch.
7| Fair. W 25 30. 40] 20.21 145
30. 48] 30.25 | 48
Beale cee liar
quer Se SS ed ee | ee eee fee
Total rain 1.54
K2- March
63 Mr. Avxins’s Metéoroleccal Yournke: ;
.March 1782:
= = , Barom. oe 2
Bis Weather. Windgy {Clouds.{ 192 | 100 3 Rain
; paris. pyparts |)
ae : Inches. |Inches, 5 ine.
61 Fair W 10 90. G80. O- jae
2 29.186) 29.97) 45
9| 40 29-174) 29-91 | 40)
6l Fajr |WNW 15 29.170| 29-89 |38
gersc: 29.176) 29.92 145
| cal Cloudy NW 29. fe 29 94 |40
frome Bored ners ee (| re ae ie —); ——
6|Fair, white froit, NW fo) 2g.186} 29.97 |39
12 30. 0} 30. 0 |47
9 20 30 16) 20. 9) 42
SB Po | 2 ‘ 2a Mel
6| Hard froft, W O 30. 30) 30.16. | 322
12 30. 161/20, osha
9 20 30. ae? 9 {37
6|Little frott. WSW 30 29 178) 29.93 |38
5|12 29 170} 29.89 |45
2g. Lie (20-989 49
6) Fair. IWNW 10 29. 108) 2 2Q. 1.83 40
6} 12 29.168! 29.88 |50
9 29. 64 205 86 [47
Fait W 20 29-158 29.83 40
7) 42 29.150} 29-78 |44
Q| Showers 75 29.144! 29-75 48
6|Sleet, but fnowon the hills.| SSW 70 29.144] 29-75 |39
12 50 a9. 32199.17 140
9| 1 Very great ftorm of |WNW 28,112| 23.59
10 } wind and rain. go 28.120] 28.63 137
6| Fair. WbyN 40 29. ye 3g 0.82
Q|12|Showers. 29. 60/29 31 145
Wi 29-132] 29.69 142
March.
Rept at Minehead, i Somerfetthire, 69°
March 1 78 vied
at ie
wit ‘ Barom. Barom. | =
KS = Weather. Winds, 'Clouds.| 192 £00 2 Rain,
: | parts. | parts. (2
: re {nches, \Inches o|luch.|
6 Showery day. SE 20 29-144) 29.75, |42
yO} 12 SO 29.140) 29.73. 150
9 W. 29-140) 29.73 | 48
6) Fair a ae 29 138) 29.72 |45
11] 12 40 29. 99| 29.50 | 53
Q|Very flormy. 85 29. 48) 29.25 148
| 6 'Stormy. NIE a8 29. 92) 20.49 "| 42
12|12!Hail fhowers, / 29.140) 29.73 145
Q|Fair. 80 29 184) 29.96 | 39
6\Fair and frott, Ni ae WwW 30. 12] 30. 6 24
13/12 30. 20] 30.11 |46
9 WSW 15 30. 10} 30. 5, 140
Des froit, PN. 2g BOr Oil Bertani ag
14} 12)Fair, 20.,16) 30. 9 | 44
9 30» .16} 30. 9 137
6\Fair, frof, JWNW 25, 30, 24] 20.13 |33
I5|i2 30. 26] 30.14 | 40!
g|Cloudy. 2G. 20) 30:1 1) 40)
“| 6| Fair, NNE. - 301 olovamr Urbinetorye(ay 123
16/12 20.' 17)| 20s fone
9 W 30. 10} 30. § |40
_.6\Cloudy, NNW 35 30. O] 30. O | 38j)0.10
17\12|Fair. | 29.188! 29.98 |45
| 9 29.190} 29.99 |40
6| Hazy. | WNW 10 30. O} 30. OQ; 137,
18| 12|Somewhat fair, ; 29.186] 29.97 |45.
g| Cloudy, 29.180] 29.94 |41
I I —— om — SS a —_ nt en ee tt =
March.
ae
a
70 Mr. Arxins’s Meteorelgical Fournal
March 1782
eg
:| Barom. |Barom, | &
Als Weather. Winds. |Clouds.| .192 100 | §
parts. } parts. |
| Inches. {Inches. > {2nch. |
6/Cloudy. Ww 25 29-150] 29.79 las
19/12} 50me {mall rain. 29 136] 29.71 {50
9 29.120} 29.63 |42
6| Hazy. SWE. FS 29-140} 29.73 | 309
20|12}Fair. 29.152} 29.80 45
9 29-144) 29-75 |41
Sleet, but fnow on the}, -
. A ! diftant hills, opal: 29 128) 20,00 lag
eS ea 29. 96} 29.50. 135
| 9 29+ 40] 29.21 |35/0.40
C} Ditto. E 60 , | 28.160] 28.84 133
29/12 28,170] 28.89 |34
6| Exceffive froft, with a little) E 10 29. 20] 29.11. |27
23/12} {now here, but-five or fix) N 29. 32) 29.17 135
g| feet deepin the country. |NW 30 29. 88} 29.46 137
6] Some fhowers. NW 50 29.100} 29.52 140
24) 12 29+ 90} 20-47 43
9 29-100} 29.52 [40]0.33}
6] Cloudy. Ww 30 29.108] 29-57 140
25) 12) Fair. 29.112] 29.59 |47
9 . 29.128] 29.67 139
6] Showery. | [WNW 25 29.144] 29-75 145
26|12 29.140] 29.73 |50
9 29140] 29.73 148
6] Showery. Ww 32 29.128] 29.67 |48}
27,12 29.120| 29.63 |51}0.17
9| Hard rain all night. SW.) (ees 29. 88] 29.46 |48
March
\ kept at Minehead, 7 Somerfetthire. 71
March 1782.
Barom. |Barom,
Weather, Winds, |Clouds,} 192 100
parts. | parts.
Rain.
Day. }
Hou
| Thermom.
SS ee
Inches. {Inches. } _| Inch.
| 6) Hard rain. SSW 50 AGS!Z2129: 17), Ea
2§|12/Fair and mild, 30 29. gO] 29.47 155
9) Cloudy. 29. 72| 29-37 | 50} 1.25
ae rain. WSW 60 Sau Via wma ed ey ay ir]
29 12/Fair. , \ 29. 60] 29.31 {50
| 2g- 78) 29-41 |49
y 2
6|Fair. ~~ |WNWsel - 29. 32} 29.17 148
30/12 29. G4) 29.34 155
| 9| NW 29. 92| 29.48 |50
—|— | a fp | | a | ee
| 6) Very ftormy. Ww 60 29. 38] 29.20 147
31| 12|Showers. 29. 56} 29.29 |50
9 8c 29. 46] 29.24 |46/ 0.34
_. Total rain 3.91
Apri
cy
April 1782
ee Wreather. Wings.
A\x
Hard rain fhowers;- the
6| bar. fell till 8 in the even-}SE 60
12| ing: after whichit rofe1|SSW = 50
r| 81 line by 103 after which; W 30
g| the wind rofe to a great
10} ftorm, but no rain. WNW
6 NW 90
2.1 12
| 9 719
eg ——— Oe Oe ae ee
6 {Some thowers. WW = 50
3)12\Fair.
1-9
| dlctowty. WNW 40
| 4112/Fair.
| 9 10
}
—|—|—_——_— APO PT SD TNE.
6|Hard hail fhowers. FE. 40
5|12\Fair. NW 25
9
6}Showers. WNW 39
6/12 E NW
Q| Hail fhowers. NE 40
6 | Cloudy. INE 50
7112
9
— | — 8 ay
6jCloudy. INE 30
8 | 12|Fair.
9
6)Cloudy. |NE 20
Q a |
lo
Mr. ATKINS's Moteorologice L Fournal
ot ®
\Barom.
100
parts.
jBarom,.
192
parts.
Clouds.
—_—
Inches. Inches.
29S OPO
28.116|28.61
| 28. 96| 28.50
138. 44] 28.23
|28. 60| 28.31
28 140) 28.72
8.126 | 28.82
23.172| 28.90
29. 96
29.108
29.112
29.50
29°57
29°59
29.67
29-82
30. O
ee
|
29 156
29.184} 29 96
29.186| 29.97
| 29.1861 2g 97 |4°
44
April
Rept\at Minehead, zn Sonterfetthire. 3
April 1782.
Barom.|Barom,
(29-144) 29-75
| 29.123] 29.63
29. 96} 29.50
29. 80} 29.42
29. 80] 29.42
29. 62] 29.32
29. 50| 29.26
29. 50} 29.26
29: 44) 29.23
29. 72 29.38
29. 80} 29.42
Ee SN eS)
a ISloudy.
6} 12. Showers.
Vot. LXXIV,
74 Mr. Atxins’s Meteorological Fournal
April 1782
, E
bal 5 - Barom. |Barom, | 2
14 lx Weather, Winds. |Clouds.| 192 | 100 |§
parts, | parts. |
Faire Inches. Inches. | ,{Inch.|
6 ESE 25) 29-112} 29.59 |40
2
29-116} 29.61 |44
9 29.116) 29.61 jar]
6 |Showery. E 15 29-128) 29.67 ie
20|12 29.128] 29.67 |45
9 29-140) 29.73 {40
6]Rain. E 20 29.130}29.68 |4;
21/12 SW” 35 29.120].29.63 |46
9 29.128] 29.67 |r
6| Fair. SW = 40 [29.115] 29.60 |50
22/12] A little rain. 29.126] 29.66 | 56
| Fair. SE 45 29.123] 29.64 |46}
6| Fair. SW 30 29-110] 29.57 |46
23|12|Showers. 29-115] 29.60 |55
9 29-107) 29.56 149
6] Showers. SE 25}, 29. 78) 29.41 |50
24/12 29. 66] 29.34 |4o}
9| Hard rain. . 29+ 51/ 29.27 |50
6) Fair. Ww 20 29+ 73) 29-38 |49]0.67
25) 12 SE W | 29. 96) 29.50 |50 ;
19 29. 96) 29.50 |49
| 6| Fair. E 30 29.112] 29.59 |48
26] 12 . 29.116] 29.61 |50
9 29-126] 29.66 147
6} Cloudy, biack eafterlywind.|E 55 29.142] 29.74 |45
27112 29.142] 29.74 |49
9 29.146] 29.76 145)
kept at Minehead, in Somerfetthire? 75
, - Batom, |Barom.
Weather. Winds, {Clouds.} 192 100 |
lt parts. | parts.
ye Inches. |Inches.
6} Cloudy, blackeafterly wind. |E. go 29.140} 29.73
8{12 : 29-140] 29-73 | 46]
r 29.136] 29.71 | 42} -
woes J ie fee a
Oirein all days bubddow on\”
se
6|Cloudy, froft.
30) 12) Fair.
9
76 Mr. Atxins’s Meteorological Fournal
29.180] 29.94.
ay 182] 29. 95
29.170 29.8 H
29-166 29.87 acl.
29.150] 29-79
29.146] 29.77
———
—
29.164] 29.86
29.165] 29.86
29+173{ 29-99
29.169} 29.89
29.160} 29. $4
29.128] 29.67
29. 96] 29.50
| 29. 86] 29.45
29+: 94) 20,49
Rept at Minehead, iz Sonterfolth ite, oy
May 1782.
cg .|Barom. |
Weather. 100
eee | ae ee
Bg ENE 30}
yO}12/Mild rain. © i: 3
' giShowers. «=: WNW
SSW 25
9 Cloudy,
May 1782.
Winds, |Clouds.
NW 50 50
60 29.136] 29-71 155
29.160] 29.84 |50
\sw 3° 29.176 29.92 Iso
29.170] 29.89 {54
29.146] 29-77 |50
| 30 29.154 29.81 450
29.173] 29.90 {56
29.170] 29 89 153
SW 25 | 29.144] 29.75 |48
kept at Minehead, én Somertfetthire. \ 79
May 1782.
&
- Barom. |Barom. 5
Weather. 8
Clouds.| 192 100
parts. | parts. |
Inches. |Inches. | .| Inch.
29-140| 29.73. |60}
'29.1341 29.70 |60
29.106}.29.55 |62
28|12'Rain.
. 9|Hard rain.
eee see | eee | —— |
6|Rain. S 30 29. 96] 29.50 |60
= (29+ 88t.29-40 | 58
9|}Cloudy W 29- 9O| 29.47 |52| 0.33].
6| Small fhowers.
29. 94| 29-49 | 57)
12|Fair at intervals.
29-106] 29.55 |62].
9 29.106] 29-55. |55
6| Cloudy. W. fe) 29. 96| 29.50 |52
12|Hard flowers, 29 96| 29.50: |60
9 29. 90] 29.50) 158} 0.28
‘Total ‘rain 3.23:
June. |
$0, Mr. Arxiss’s Meteorehgieal fournal
Weather.
wee
NE 30
NW by N
NNW 40
NW
gees
er
SE o
SSW 10
S by W 25
June 1 7e2.
| Winds, Clouds.
— ee
See
oe
ee
iS
Barom. |Barom. 2
sie 100 | § |Rain.|
Gq |
parts. { parts. | 64
Inches. |Inches. |
29.128 29.67 Aq
29.138) 29.72 | 56]
29-124 : 29.65 49 :
29.190} 29.99 55 |
30+ 4) 30 2 |§0}0.31 |
| eee |
-
30. 8 30. 4 50 :
30 16 30. 9 56 |
30. 19] 30.10 | 52}
30. 18} 30.10 | 52! |
30. 10} 30. § |60},
30. ©} 30. O |50
3O- 24-90. df GSde nn
30 4 30. 2 52
30. 6) sos
30. 6) 30. 3 {60
30. 6/30. 3 152
30. 5 30. 3 50
30. of 30. 0 67
29.184] 29.96 |60
a
29-163} 29.86 }55
29.152] 29.80 7O
29.138] 29.72 157
29.100} 29.52 56
29.108] 29.56 167
29.112 29-59 57 0.50
June
epi aé Minchead, 2 Seimerferfhire, °
4
June 1782.
or
a E Ns Barcm.|Barom. | 2
a ie Weather, Winds.: {Clouds.| g2 | 2CO ls Rain
parts. {| parts. |B
Inches, jInches. | .|Inch.
6|Showers, WwW 30 29. 62) 29.31. 1§2
nO) 12{|Fair. 29. 76] 29.40 es
g |Showers. 29. 76] 29.49 |60
6 |Showers. WwW 20 29. $71 29930.155
Ur] 12|Fair. 50 29. 96/ 29.50 |62
9 29.116] 29.61 | 58)0.29 |
6 |Showers. W 20! SE | 29. 56) 29.29 | $5 |
12 12! [SSE 30 29.112] 29.59 |63
9 W 7 29. 761 29.40 155
6 |Showers , WwW “50 29. 82] 29-43 | 51 |
13/12 |Fsir, 29.116| 29.61 |62
9 |Hard rain. 29.134| 29.70 |55
6 |Showers, WhyS 75 29.144] 29,75
14|12 \Fair and hot, 29-150] 29.79
9 29.160} 29.84 |60
6 |Cloudy. WSW 20 29.184] 29.96 |61
1§|12/Fair, very hot. 50 30. Oj} 30. O 175)
9 10 20; 24|30.°2 |G0
6 |Foggy. SE ro} W | 30. 16] 30. 9 .} 6c
16) 12 |Fair. NW: 30 20. 321 30.17 172
9 SW 30. 24| 3018 160
6| Fair. ESE 20 29.188 29.98 |60
ry Ta) S by E 10) 29.164] 29.86 |71
4| Exceffive hot, ther. rofe21°. 81
q 29-150} 2979 175
6) Flying thunder:fhowers. {NW 10 29.154| 29.81 167
18| 12/ Fair. WNW 29.172| 29.90 |67
9) 30. Oo] 30. 0 158 |
Vou. LXXIV. M June
82
Mr, Areins's Meteorological "fournal
June 1782,
Ae. ie Barom, |Barom, E
4 |i Weather, | Winds, |Clouds,| 192 -} 100 | § |Rain,
parts. | parts, a
a ‘Gener cle mo Inches. Inches. ube Inch.
6|Fair. WNW 10 30. 16] 30, 9 58
19{12 30. 34] 30.18 167
9 30+ 32} 30.17 |60
6|Fair ENE. 10k, W...| 30. 32) s@camailicg
20|12 WSW 30. 381 30.20 168
9 30- 38] 30.20 |64
6|Hazy. NNW if, 30. 44] 30,23 |60
'21|12| Hot SW | 30. 57} 30-30 |7o
9 30. 76] 30.40 167
6|Fair and hot. W 25 30. 76] 30.40 |60
22/12 30. 76) 30.40 | 71
g SE SW | 30. 76] 30 40 |60
6|Fair, very hot. ENE 30 30. 72| 30.38 | 59
23/12) 30. 61] 30.32 174
9 ESE 40 30. 48! 30.25 |66
| 6} Fair, very hot. ESE 20 30. 30] 30.16 |62
24|12 Sby E 10 30. 22) 30.12 1/76
| 9 30. 19] 30.10 |67
ne De ME oe Weed SI als (ca Hy BAU ea |e BRE
| | 6| Fair. Ww fo) 30. 8} 30. 4 167
i _| 12] Exceifive hot. E 22| SW | 29.186] 29 97 177
Ske | 80
| | 9 is 29.184] 29.96 |72
ae res ES mae >)
|} 6) Foggy and cooler. WNW 25 29.184] 29.96 |61
26| 12 Fair. 29.184} 29.96 |70
aay tae 29-184] 29 g6 | 58
SSS { ee ee eee a eS a
6} Fair. |E O 30. 10] 30. 5 157
j27| 42 | WNW 30 30. 10| 30. 5 jay
i | 9 30. 0} 30. o | 50
kept at Minehead, em Somerfetthire, 83
| June 1782,
Barom. | Barom.
Clonds.| 192 100
parts.
omens panseequee | ee See | eens | ap seeemer | nee
Ww 10 29.176 29.92 61
30|12|Hazy. WNW 29.180} 29.04 |67
| g| Fair. 29.180} 29.04
Total rain 1.44
M 2 July
Mr. Arxins’s Meteorological fournal
July 1782.
Z{ 2: Barom. |Barom. | 2
Ais Weather. - Winds. |'Clouds.| 192 100 | § |Rain,
} at parts. |/parts, |Z} | |
\Inches. jlaches. . ; Inch,
6 |Cloudy. WNW 20 oh 088 8h) 4
1| 12, i 29,184| 29.96 |62) ) |
g|A hard fhower.: 29-172{29 90 |57 .
| 6 Flying clouds, NW 40. 29 1441-29-75 158
alia 29.146] 29.76 16a)
9 29-152 one 37 0.97
6 | Hazy * WNW is 29.182 29-95 59
3\12 |Fair 29.186} 29-97 462)
| 9 | 29.180] 29.94 158
6 |A little rain. WNW 30 29-162] 29-85 |58 |
4{42 |Hazy. 29.166] 29 87 -|62
; g | Fair 29.170| 29.89. 155
6 | Pair and cold, WNW 10 29 158 29.83 50
12|Rain. 29.140] 29-73 |61
9 29.130] 29-68 |58}0.28
ae | ee es Se Ss as | ees —) a | owe
6|Rain SE 20| SW | 29.122] 29.64 |59
6|12 E 35 29.134] 29-70 |61
9 NE 29.150| 29-79 |60/0.23
6|Foggy, rain. INE 20 29.162| 29-85 |59
7{12|Fair. 29.162] 29-85 |62
g |Cloudy. fe) | 29-106 29-85 |60
| 6 |Cloudy. E 24.167| 29.88 |60
| 8{12 Pair. WNW 40 29.174] 29-91 |63
| g |Cloudy. 29-174| 29-91 |58
6|Fair and hot. WNW 45 29.156] 29.82 |60/0.13
g|12 29.160] 29-84 |70
9 29-170] 29.89 |59
ts
3
a
| 6|Cloudy.
12|Fair.
9
6|Rainy day.
12
a
17
18
et
On Wd
—
6/A little fhower.
Weather,
eee
12 |Cloudyand fairat intervals.
9 (Hard fhowers.
6|Rain.
12
9 Hard rain.
Cloudy,
Fair.
a]
fy oS
Hazy.
Fair.
IRs Sox bo B ates
—
12;
9
Fair and hot.
Hard rain.
6| Fair and cold morning.
en es Se eee Se
ere 9 Ge ee
ease Se Ge
ees ee es Pe
r
Thunder fhowers.
re ee
eee
July 1782.
Winds.
WNW 201:
SE 30
SSE
WNW
W OQ
S by E 30
W
W 20
iD fe)
NW 10
SE
S by E 30
NW
WNW 15].
Clouds. 192
parts.
f {nchkes.
29.168
29.170
29-175
29 154
29,128
29.100
290099
29.144
29 152
29.164.
29.132
2.9.100
29.128
29.140
2051.52
2.9.164
29-074
29.100
29.154
29-150
29.144
29.166
29.170
29.186,
elo MalWne)
30. 16
30- 32
| Barom.|Barom.
kept at Minehead, iz Somerfetthire.
85
Rain,
eee
Inch.
59} |
oo
56)
60} |
g
=
Cc
100 iG
parts. By,
Inches. y
29.88 |59
29.89 |60
29-91 | 58
29.81
29.67 |60
29.52 158
29.64
29-75 |68
29:60 |58
29.89 | 59
29.69 |61
29952 |58
29.67 | 59
29-73 [04
29.80
29-86 |60
20191 174
29.84 165
29.81 | 59
29.79 {65
29.70 |60
29.87 |58
29:89 | 61].
29:97 | 59).
30. O | 50
30.9: 48 ||
30.17 |62
July
Mr, Avins's Metecrolagical Yournal
9 INW
July 1782.
g
5 EBarom. |Barom, | 2
= Weather? Winds, |Clouds, |. 192 1oo |
: parts. | parts. |
Inches. {Inches. |
6| Fair and hot, Ww 10 30. 40| 30.a1 64
12 E NE | 30. 48} 30.25 {72
BC) 30. 36) 30.19 165
6|Fair. WNW 1 30. 38] 30.20 162
ie E ENE | 30. 30] 30.16 [64
Ihe 39- 24) 3°-.ES ae
6| Fair. ENE 10 30. 24] 30.13 164
12| Very hot. 30. 16] 30. 9 174
9 30. 0/30 © |68
6| Fair. E 30 29.160] 29.84 161
12| Exceffive hot, 29,1521 29.80 |80
) 81
g| Flying fhowers. S by E 29.140] 29.73 |68
6| Flying fhowers. S 10 | 29.146] 29.977 |64
12 29,150] 29.79 174
9 | Fair, 29.154] 29-81 165
6|Cloudy. SW 35} NE | 29.158] 29.83 |63
12|Some finall rain. 29.106] 29.87 |71
g|Cloudy. Ww N 29.173] 29.90 |60
6 | Fair. SW by W qo 29.188] 29,98 | 59
12 ENE | 29.199] 29-99 {95
9 Ww 32, 0} 30. O |60
6}Cloudy. SW 20] N 29.154] 29.81 | 58
12] A hard fhower, WNW 29.162] 29.85 | 64)
| Fair afternoon. NE 29.172] 29.90 }59
6|Rain, NE 30} SW } 29.156] 29.82 }61
12 29.150] 29.79 |63}
| 29-140] 29-73. |60
July
\
kept at Minehead, i# Somerfethire. 87
Barom, |Barom,
Winds, |Clouds.| 192 | 100 Rain,
parts. | parts. jf)
Inches, /Inches.
W 25 29-140] 29-73 |60
29-132] 29.69 |62
29-138] 29.72 |60
E 10 29.150] 29.79 |60
Ww 35 29.154] 29.81 |70
NW 29.163! 29.85 |60
29] 12) Hazy.
9A little rain.
NER 26 29.170! 29.89 |56] 0.77 :
NE | 29.172] 29.99 |65}:
WNW 4o 29.174] 29.91 |58
6| Cloudy. WNW 15 29.160] 29.84 56 |
31|12/Some rain. SE | 29-156} 29.82 |62)
g
SW 29.144] 29.7.5 |60
oe
Total rain 2.93
Auguit
Mr, Arxine’s: Meteorological Fournal
Augut 1782,
4 : I = |
pe . ae Barom. |Barom, | & |
Bikes Weather. Winds. {Clouds.) 192°!) FOO | 5°
a f parts. | parts. ea
tr; ; | : Inches, |Inches. | |
6| Flying fhowers. NE 30) S | 29.349) 29-73 |58
1/12 29.128] 29.07 |68
9 29+ 9O| 29-47 |60
6| Fair. NE Qh S | 29. 70) 20-27aie6
2|12|Showers. WSW 30 29. 60] 29.31 166
9 Showers. WNW 2Q- 72 29.38 60 x
6| Fair. NW. 40 29» 75) 29-39 {60
3] 12 WNW 29-110] 29.58 -|67
9 29.113/ 29.60 |60
6) Fair. WNW 35 29.122] 29.64 |58
4|12 29.134] 29.70 |64
g|Showert. 29-144] 29.75 |60
6|Some rain. Ww 1Q 29.176) 29.92 |57
5) 22|Fair. 29.168] 29.88 |65
9 29.160] 29.84 | 59
6) Showers. Ww 29.126! 29.66 | 58
6] 12|Fair. SW 29. 96| 29-50 |68
g|Thunder fhowers. S 29. 48] 29.25 |60
6)Hard rain. ESE 20 28.186) 28.97 |57
7|12)Very ftormy. NWro0 29. Ig} 29.10 |51
2 29+ 39] 29-29 155
6! Very ftormy fhowers, NNW 90 29. 56| 29-29 |56
| 8}12|Stormy, but fair. sO 29.100] 29.52 |64
9 75 29.125| 29.05 |60
6|Cloudy, NW 40 29 120/ 29.63 |58
g| 12|Showers. | 29.116! 29.61 |62
29.122| 29.64 |60
Go
wis a Minehead, ‘tn Sormerfetthire.
“Auguft 1°82,
oo
\e
{
Ze hie |
| E ait Barom.{Barom. | & | |
45 15 Weather. Clouds.| 3192 | 100 | § {Rain.|
parts, | parts. |= |
ee See cA ee en ee
i Inches. |Inches. |, tach. |
6|Smail fhowers. 20,1351 29.71 (be
10/12|Fair at intervals. 29.140] 29.73 |60 |
9 2.9154 29.81 |57 |
61\Fair. 29.160] 29.84 |58
II|12 29.160] 29.84 |61
9 2.9.156| 29.82 | 52
6|Cloudy. 29-134] 29.70 |58 (
12|12|Hard rain. 29.105] 29.54 |55
9 29-100] 29.52 1152
6 |Fair 29.100] 29.52 |57|0.54
13/12 |Flying fhowers. 29. 76) 29.40 |64
9 |Hard wind and rain. 29. 36] 29.19 |60
6 |Hard fhowers. 29. 34/29.18 |63
{14/12 |Fair. 29. 30| 29.16 |68
9 |Cloudy. 29- 24] 29.13 |60
6 |Cloudy. 29. 80] 29.42 |62
15}12(Fair. 29.100] 29.52 |68
9 29.116] 29.61 |60/0.23
6|Rain. 29. 48] 29.25 | 56
16| 12 |Fair. 29. 60] 29.31 |64
9 |Cloudy 29. 86) 2945 159
6|Cloudy WNW 30 29. 861 29.45 |58
17|12{Fair. 29. 86] 209.45 |00
9|Cloudy 29. 86) 2945 | 59
6) Fair. Nw 5 Leaies| 29.72 |60
18/12 \WNW 29.140] 29.73 |O4
| o| Showers. | 29.144] 29.75 |60
Vor. LXXIV. N Augult
90 Mr. Arxins’s Meteorological Fournat
Auguft 1782.
\g
215 Barom. |Barom. | 2 |.
A ae Weather, Winds. jClouds.| 192 100 | 5 |Rain.
parts. | parts. |
Inches. jinches. | | |Inch.
6} Fair. SE 10 | 29-134 29-70 |59/0.17
19/12 29.140) 29.76 {69
9| Cloudy. NW 29.148 29.77 |60
6|Cloudy. SW 40 29-148] 29.77 |58
2.0|12})Showers. WNW 29.144] 29-75 |70
9 29-144.) 29-75 60
6) Fair. WSW 25 29-152| 29.79 158
21/12 SW 29-148} 29.77 {71
9| Showers. 29-154| 29.80 163
6!Showery day. SW 40 29-1441 29.75 |58
22}12 WSWw 29-134] 29.70 |67
9 29.122] 29.64 |57
6| Showers. W 50 29.126] 29.66 |56
23)12| Fair. NW 29.138] 29.73 |67
g| Cloudy. SW 29.154| 29.81 |60
6) Cloudy. SW 20 29-150} 29.79 158
24/12] Showers, 29.115] 29.60 |70
9 WNW 29. 96| 29.50 |60
6| Fair. WSW 25 29.106] 29.56 |59
a5|12 29.134] 29.70 |67
Q| Showers. Ww 29.150] 29.79 |60
6] Showers; WSW 20 29-154 29.81 60
26/12 29.163} 29.85 |70
9 29-173] 29.90 |6110.64
6} Fair. NW 45 29.1381 29.72 |60
27) 12 29-135} 29.70 |64
9} Hard rain, WNW 29.106] 29.55 |60
Augutt
kept at Minchead, zz Somerfetthire. 91
. Augut 1782.
Winds. |Clouds.
6 |Fair. 29-122] 29.64 158
28) 12 |Cloudy. 29 134) 29.70 |62
9 |Showers. , -29-130| 29.68 158
6 |Showers. 29-L11] 290.58 |52
29| 12 |Fair. 29.118] 29.62 |59
29.123) 29.64 |54
g |Hard rain.
6 Showers. 29.142| 29.74 55\
30} 12 |Fair. 6] 29.81 159
9 . 29.182] 29.95 152
6 |Showers. 30. 2 |§2
31/12 |Fair. 30. 16] 30. 9 |60
9 |Rain, 530. 24) 30.13: 155] 0.50
Total rain 4.19
N 2 . September —
9%. Mr. Arxtns’s Meteorological Journal
September 1782.
> : g ra 5)
“| 5 Barom. |Barom, | § |
ale | Weather. 192 | 100 | § |Rain.
parts, | parts. |
| Inches. {Inches. Inch.
6 Cloudy. 30. 32] 30.17 159
1|12/Fair. 39. 37| 30-20 j6o0! . .
g {Cloudy 30- 40] 30.21 | 54/0.17
6 |Cloudy.. 30. 52] 30:27 |60h |
2|12/Fair. 30. 66} 30.34 168}.
9 30. 48] 30.25 | 581.
6 |Cloudy, 30. 29| 30.15 152 |
g\12 182 30. 20] 30.11. 167
g |Fair 30. 5] 30. 3 }66
6 |Fair. 29.180} 29.94 155
4|12|Hot. 29.180} 29.94 |71
9 29.184] 29.94 |60
30. 0] 30. 0 |52
5 site 30: . 5/30: 3°} 90
6|Fair. 30. 10] 30 § 155
6}12 30. 15] 30. 8 |68
9 30. 15] 30. 8 {60
6|Fair. 30. 18] 30.10 |60
7\12 30. 18] 30.10 |70
9 3O- 20] 30.11 |60
; 6 | Fair 30. 24] 30.13 157
12 30. 24) 30.13 167
9 30- 20] 30.11 |60
6|Fog 30. 24} 30-13 |€0
g}12|Fair. 30. 24] 30.13 [68
9 30. 14] 30. 8 {62
September
kept at Minchead, iz Somerfetthire,.
Septembet 1782.
&
es = ‘ Barom.|Barom. A
a = Weather. Winds, |Clouds.} 192 (clo nna
parts. | parts. |e,
6|Foggy. B 15
1O| 12|Fair.
9
6 | Fair. ENE 30
II} 12
9 5°
6 |Cloudy. JE 50} - 29-179| 29-93
£2) 12, 30. O/} 30. 0 [56
9 | Fair. 20.121 20.6. Gal
6 |Cloudy. E 20 30. 121 20. 6 55
13/12|Fair. 20, OlzON0Gr
9 W | 29.184| 29.96 |58
6|Cloudy. E OH i Biot 29.170} 29.89 | 57
14} 12 3 29.165] 29.87 164] :
9 29.144) 29.75 [60].
6/A little rain, S 254° | 29. 96| 29.50 58
15|12/Fair. ESE 29. 04] 29-34 }63
a | 29. 48] 29.25 160
| 6]A little rain. S 10 29. 20] 29.11/60
16| 2 Hard rain. BGEL US 29.. Tatoagh 7 seg
20, OC) 20.10
g|Stormy wind andrain. {SW 975 BO SAND O 4G
6| Fair. | Wi 25) 29. 48) 29.25 |55
17} 12| Showers. 29. 57} 29.30 63
9}. 29. 57} 29.30-|58|0.61
_ | 6|Showers, WNW 20), 29. 48] 29.25 |§5
18] 12 : | 29. 20] 29.11,1168)
9 79} 29. 571 29-30 |5°
September.
Q4 Mr. Avxins’s Metecrological Journal
September 1782.
Barom.
Weather: Winds. °|Glouds. | 192.
parts.
ES
: Inches.
Fair and cold. 29-130
29.170
29.176
—
taal
nD
bro
ere ey Se ees Se
Showers; 29.150
29 142
i)
@)
4
ND
Cloudy.
Hard rain.
Fair, Kiet 29.100
Hard fhowers, 29.100
29. go
Showers. 29.470
29. 80
ee
A little fhower, WNW 10
Cloudy.
Rain, 29.170
9
6
12
9
6
12
9
6
12
9
6
12
9
6|Showers. WNW 5 29.156
12| Fair and hots 29.164
9 29.164
Barom,
100
parts.
| Thermom.|
Inches,
29.68
29.39
29.92
eee eee
29.79
Stormy. 29.140} :
29.89
29.82
29.80
29.80
12} Fair and hot. 29.160
6| Showers. 29-160] 29.
g| Cloudy. 29.160} :
—_ ee ee —
6} Rain. 29-125
12 29.150
Q| Fair, 29-182] 2
September
ets
| 5
Alt Weather. Winds. {Clouds.
6}Cloudy and cold, SW sto
> 35
g|Rain.
6] Fair. W 20
29 | 12 |Showers. &
g| Hard rain.
6| Fair. Nw 60
30] 12 Showers,
9
Rept at Minehead, i Somerfetfhire.
September 1782.
93
Barom, |Barom.
192 100
parts. | paris.
| Thermom.
Inches.
2084 0
20682
29.180] 2
Inches.
See 18)
29.170
29.140
29.128
29.116
eae
29.180
1.33
3-90}.
Total rain
October:
ta
96 Mr. Arxins’s Meteorological Yournat
Oaober 1782.
f Ai
fi. je Barom. |Barom. | 8
A g Weather. Winds. {Clouds.| 192 -| 100 {8 (Rain
: parts. | parts. a ray
acon Oe es poet Inches. |Inches:* > |inch
7| Fair. Nw 30 39. 8] 30. 4 }49
1} 22 30. IO} 30. 5 154
! 30. O|-30. oO | Rot” a
Brill —_— S SS ee —= |= ed a .
i 4 | Showeis. WNW 35 29. 80) 29.42 |5s)
} 2/12 29» 79) 29.37 108
9 : Q- 48] 29.25 157 O4t
ta 7| Fair. NE I5 }] 29. 30] 29.16 158 |
3|12|Cloudy. 29. 60; 29.31 163) |
9 29. 80] 29.42 156 )
— oo — ee _—— = ——— ——
4|Fair and cold. RE | 36 29. 88} 29.45 |43 .
4}12 29+ OO) 20-2 Innes
g| Cloudy. 30. 12] 30. 6 |50
a 4|Fair. ENE ia 2.9.172| 29.89 145
5|12 29.180! 29.94 |48
ra ine) 29.186) 29-97 148
4 | Fair. E 25 30. 613% 3 150
6} 12 30. 0} 30. O |56
g|Cloudy. 29.184] 29.96 |51
7|Cloudy. WNW Io 29.175} 29-91 |50
7) 12)A little rain. 29-175] 29-91 |55
9 29.170] 29.89 |51
7| Moift clofe day. NW 30 29-164} 29.86 |53
8} 12 29.160] 29.84 |56
9 29.160] 29.84 | 51
7|Some rain. | ESE 24 29-154] 29.81 |53
g|12 29.140] 29.73 |57
9 | 29-136) 29.71 |54
October
Rept at Minehead, 7 Somerfetthire. 97
ween eens tree oa OR A ATR ts REO ny st meme Ay
ve Barom.|Barom,
- Winds. |Clouds.] 192°} 100
parts. | parts,
| Thermom.
Inches. |Inches.
29. 80) 29.42
29. 40] 29.21
29. 16] 29. 9
29. 16] 29. 9
29. 40| 29.21
29.31
29-44
29.46
29-57
29.68
29.81
29.85
7 |White froft. . 29.96
320. O
SISOS:
alo)
Boo 9)
oC
ed
Ets. ered okie
L al
\O Ww ~y
Heb)
30.10
30.11
20.13
30.15
Bey
30.31
30. 72} 30.38
30. 66] 30.34
Vou. LXXIV. O | Otober
gt Mr. Arxins’s Meteorological Fournal
O€tober i782. | er aa
Barom. |Barom,
Winds, |Clouds.| .192 |. 100 Rain.|
parts. parts. a
Inches. >|2nch.
Weather, |
Inches.
7|Some little rain. WNW 60
Stormy wind.
29.86 |50|0.42}
ae
12,
9
7 Fair,
20)\12
g|Rain.
7|Rain,
21)12)Fair.
9} Cloudy.
ee ee ee 1
7| Cloudy.
22)12
g| Rainy night.
7| Fair.
Vee
7\Fair, froft, 30.20 | 39
30.25 152
30.30 | 50
30-21 [47
rs 0 ne ee
7| Showers.
5
39-29 154
30.25 158
30-17 $57
4 October
kept at Minehead, ix Somerfetthire, 99
“Odober 1782.
4 &
ae Barom. |Barom. | &
ages Weather, Winds. |Clouds.| 192 100 «| G| Rain.
mF parts. | parts. 2 ;
Inches. {Inches, | | Inch,
7 | Fair. Ww 29-184] 29.96 |50
28|12/|Small fhowers. 25 29.176] 29.92 |55
9 | Stormy’ fhowers.) - 45 29-104) 29.54 |54.
7\Exceflive ftormy, but dry. |}WNW 90 29.136] 29.72 |50
29|12 NW 80 29.160| 29.84 |55
g|Shower. ! 10 Zo. *) 6) 20. 4s G 8
7\Rain, | WNW o BO. 701 SO. OL airs |
30] 12 29.140] 29.73 |52
baa # 30 29- 96] 29.50 |50
7 Showers. NW. 26 29- 68) 29.36 °|48 |
gt) t2 . 20. Oo ae
9|- 30. 0} 30. O 46) 0.46
Total rain 1.69
Qreerers “Serr Nove mber
400 Mr. Arxins’s Meteorological ‘fournat
November 1782.
| E
ile {Barom, |Barom. =
ra ee Weathers — Winds. .|Clouds.| 192 roo | &
parts. | parts. |g
Inches. jInches. |.
8 |Cloudy. SE 15 30. 0] 30. O |42
1|12|Showers. 29- 97] 29-50 |4q
9 30. 6) 30 3 145
8|Rain. SE 30 29.170] 29.89 |45
2\12 29. 84] 29-44 |50
9 29. 76) 29-40 |43
8| Fair. NW 10 29. 6/29. 3 145
2|12|Showers. WwW 29. 12129. 6 |49
9 NE 2G. 24| 29.13 |49
8 |Fair. NW 30 29. 84| 29.44
4)12 29- 90) 29-47 145
9 NE 29. 96] 29-50 |44 |
8 Rain. Nig 35 29-104] 29.54 139
5|12 ENE 29.136] 29-71 |43}
9 NE 29-136|29.71 143)
30. 0] 30. oO | 38
30. 12] 30. 6 {43}
- §0| 30.26 137
ees es oe |
8|Fair, froft. NW 23
6|12{|Snow on the hills.
9
$|Fair, hard froft. NNW o 30. 56] 30.30 | 32
7112 NE E | 30. 64} 30.33 | 38
9 NW 30. 56] 30-30 }32
8|Fair, hard froft. NE 20 30. 32) 30.17 | 30
8}12 ENE 30. 24] 30.13 [40
j g |Cloudy. :
a g\Clondy, littie froft, NW 20
9 ee
9
|
Rept at Minehead, in Somerfetthire. rot.
November 1 782.
Z
2 Barom.}Barom, 2
= Weather. Winds, |Clouds.| 192 | 100 | 5 |Rain
parts. | parts. |
foches. |Inches,
8{Very hard froft, NW. © 29.170] 29.89
12 29.166} 29.87
9 29.164] 29.86
8 |Rain BNE 25, 29.144]29.75
12 29 160] 29.84
9 29-172) 29.90
8 |Foggy rain. SSE. 30 30. o| 30. O
12 80.) 81 BOu A.
g |Fair.. 20. 20] 30.11
! 8 |Fair, froft. _ {NW fo) ‘| 30. 80} 30.42
12|N.B. The tide ebbed and|SE V1 20. 901 20.50
Q| flowed 3 times in an hour./W 30.120] 30.63
8|Fair, froft. WwW fe) 30.114] 30.60
12 30.112 | 30.59
9 |Cloudy 30.110] 30.58
3 |Cloudy. NW 10 30.108 | 30.57
12 39. QO} 320.47
g/Rain. | 50 30. 48] 30.25
8 |Cloudy, NWe: 750 30. O} 30. O
12|Fair. 20. | QO} 20-0
9 30. 16} 30. 9
8|Fair, little froft, NNW 30 30. 38} 30.20
12 30. 32) 30.17
9 30. 30] 30.16
_ 8/Cloudy Wie el 29.176} 29.92
18} 12 29.174] 29.91
9| Small rain, 29.172} 29.g0
November
102 Mr, Arxins’s Meteorological Fournal
November. 1782.
Pe as
— | a
aS Barom. |Barom,
rat a Weather; ~ Winds, "|Clouds.| 192 i0o
parts, | parts.
Inches. {Inches,
8|Fogegy, rain. NW 20 29.180] 29.94. °
I9|12 29.180] 29.94
9 29.180] 29.94
8| Cloudy. BK 15
20|12| Fair,
? . ‘
8| Fair, hard frof. WNW o
21/12 30.,, 8
9 Be.
8| Very hard. froft, S fe)
22}12 SE
9 | Cloudy. Ww
6 |/Cloudy. NW 10
23)12 3 :
g|Snow, SE 2g. 70] 29.37
8 | Cloudy, Shy E15 29. 66
24|12| 3 29. 56
o|Rain. 29. 62
8 | Hard tain S by E 10 29. 90
25) 12 29. 96
9| Clouds 29.130
8| Fair. S 29.180
26)12 30. O
g| Freezing hard. S by E 26 30. 8
‘November
vied
‘kept at Minehead, in Somerfetfhire. 103
November 1782.
Barom, |Barom.
:
| oS 4 &
A lz Weather. Winds, |Clouds.| 192 100 | 3 |Rain
parts..| parts. a
Inches. |Inches, | .]inch.
} 8/Rain. Sby E 30 29.136] 29.71 | 29
28) 12 SSW 29.130] 29.68 |42
9| Cloudy. 29-112] 29.59 |42|0.54
8| Hail flowers. NW 70 29.134] 29.70 |40
29} 12 79-3 SA oe] as
9 E 29.134] 29.70 142
pape ee es | ee es | et ee | ee
8 San E 25 29.120| 29.63 |40
30} 12| Fair.
29.126] 290.06 |43
29.130] 29.68 |40
Total rain 1.49
December
4
¢
10% -Mr, Arxins’s Meteorological “tournal
December 1782.
¢
Ae Barom. |Barom, | 2
ra = Weather. Winds. |Clouds.| 192 100 «| & |Rain.
parts, | parts, a u
Te Inches. |[Inches. o| inch.
8/Cloudy. ENE 10 29-154] 29.81 137
1/22 29.160] 29.84 142
| Fair. 29.173] 29-90 | 39
8|Exceffive hard froft. Ww fe) 29-153] 29.80 |26
2\12 SE Ww 29.153] 29.80 35
9 ESE 29.153| 29.80 |30
8|Fair, froft. SSE 10 30. 0} 30. © | 32
312 30. 0} 30. © 135
9} Cloudy. 30. 9] 30. O 132
&|Cloudy, froft, EbyS 15 30. 20) 30.11 | 32
4}12 30. 20] 30.11 | 34
9 30. 20) 30.55 [32
8)Cloudy, froft. E byS 25 29.176] 29.92 134
5/12 29.168) 29.88 | 34
9 29.154] 29.81 |34
8/Cloudy, froft. S by W 10 29.134] 29.70 [40
6} 12 29.126] 29.66 {45
9! Mifling rain. S 29.126] 29.66 |42
8| Cloudy’. Sby W 12 29.140] 29-73 {41
7|12/Some rain. 29.140] 29.73 [49
9 29.152| 29.80 |47|0.14
8} Foggy and cold, E 15 30. O} 30. O 135
8/12 30. 8! 30. 4 135
9 30. 8) 30. 4 {35
8 | Foggy. E 20 29.1541 29.81 135
ie 29'150} 29.79 |37
9 29-150} 29:79) tam
‘ December
kept at Minehead, in Somerfetthire. ros
December 1782.
Weather. Winds, |Clouds.| 192
parts.
Inckes.
29.140
29.136
29.190
29.190
29.188
| 26.156
29.132
29.112
29. 64
29. 96
29.108
29.108
29.122
29.124
29.140
29.110
29.110
29.112
29.118
29.116
emcee | See
29.160
Barom.|Barom.
29.112] 29.
29.116]
29.128| 2
sat
100
parts.
Inches,
29-73
29.71
29-73
29-99
29-99
2.9.98
December
406 Mr: ATKINS'S Meteorological Sournal
Décember 1782.
| eam
8|Frofty and fair. 0:
==
"30.120 30.63 139
30.120] 30.63 |42
SS ST
December
kept ai Minehead, iz Somerfetthire, 107
December 1782.
= baa a Barom. {Barom. /
S Weather, _ Winds. |Clouds.|.192 | 100 Rain
parts. {| parts,
aS | ees Se ee} ee memories | ees | ee
Inches. {Inches ‘Inch,
8 | Foggy NW 40 30. 44] 30.23 138
12 30. 40} 30.21
9|Mifling rain. 30. 30] 30.16 |40
8| Mifling rain. W byN ist 30. 30! 30.16 | 40
az 2 30. 28] 30.15 | 44)
_ 9| Fair 300. 321. 90:17 13g
| 8) Foggy. NW 40 30. 40} 30.21 | 30}
30| 12 30. 40} 30.21
9 Ses 451 B07 5 Wet at
8| Fair. ENE 30 30.50] 30.26 |40
12 30. §2) 30.27 |44
69 ESE 10 30. 54) 30.28 | 38
Totaliain x19
‘Total of Rain:from the firft of: January, 31.26 inches.
E \
Sultishie he oR Pe atvs is ask
IX. | Defeription of a Meteor, ahaa Aug. 18, 18 + :
ee Mr. Tiberius Cavallo, PAR PBS |
- Read Jan..15,. 1784.
EING upon the Caftle Terrace at Windfor, in company”
with my- friend Dr. James Lrnp, Dr. Lockman, Mr. 'T.
SANDBY, and a few other perfons, we obferved a very extra-=
ordinary meteor in the fky,-fuch as none of us remembered to-
have feen before. We ftood upon the north-eaft ‘corner of the
terrace, where we had a perfeé& view of the whole phenomenon;
and as every one of the company remarked fome particular
circumftance, the collection of all which furnifhed the materials
for this account, it may be prefumed; that this defeription i is
as true as the nature of the fubject-can admit of.
The weather was calm, agreeably warm, and the fky was
ferene, excepting very near the horizon, where an hazinefs juft
prevented the appearance of the ftars. A narrow, ragged, and
oblong cloud ftood on the north-weft fide of the heavens, reach-
ing from the extremity of the hazinefs, which rofe as nigh as
18 or 20 degrees, and ftretching itfelf for feveral degrees to-
wards the eaft, in a dire€tion nearly parallel to the horizon.
It was a little below this cloud, and confequently in the hazy
part of the atmofphere, about the N. by W. 2 W. point of the
compafs,
Mr. Cavaxto’s Defeription of @ Meteor, &c. 109°
eompafs,. that this luminous meteor was firft perceived. Some:
flafhes-of lambent light, much like the aurora borealis, were firft’
obferved on the northern part of the heavens, which were foon:
perceived to proceed from a roundifh luminous body, nearly as»
big as the femidiameter of the moon, and almoft‘ftationary in:
the abovementioned point of the heavens (fee A in the an--
nexed hgure, tab.1V). It was then about 25 minutes after nine’
o’clock in the.evening *. This-ball, at the beginning; appeared '
of a faint bluith light, perhaps -fromits being juft kindled, or~
from its appearing through the hazinefs; but-it gradually in--
creafed its light, and foon began to move, at’ firft afcending
above the horizon in an oblique dire€tion towards the-eaft. Its~
courfe in this :direction..was-very fhort, perhaps of five or fix
degrees; after which it turned itfelf towards the eaft, and’
moving in a direction nearly parallel to the horizon, reached as ~
far as the S. E. by E. where itfinally difappeared. ‘The whole’
duration of the meteor was half a minute, or rather lefs;-
and the altitude of its track: feemed to be about 25 degrees~
above the horizon. A fhort time. after the beginning of? its:
motion, the luminous body paffed behind the above-mentioned —
fmal! cloud, fo that during this paffage we obferved only the »
light that was caft in the heavens: from behind -the cloud, .
without actually feeing the body from which it proceeded, for
about the fixth or at moft the fifth part of its track; but as.
foon as the meteor emerged from behind the cloud, its light -
was prodigious. Every object appeared very diftin@:; the whole -
face of the country in that beautiful profpect before the terrace -
* Mr. Ssnppy’s watch was feventeen minutes paft nine neareft;. it does not mark ~
feconds.
tio = «Ss Mr. Cavario’s Deftription of a”
being inftantly illuminated. At this moment the body of the
miecteor appeared of an oblong form, like that reprefented at B
in the figure; but it prefently acquired a tail, and foon after:
1 tparted into feveral {mall bodies, each having a tail, and all
moving in the fame direCtion, at a {mall diftance from each
‘other, and very little behind the principal body, the fize of
which was gradually reduced after the divifion (fee D in the
figure). In this form the whole meteor. moved as far as the
S.E. by E. where the light decreafing rather abruptly, the
‘whole difappeared. } !
During the phanomenon no noife was heard by any of our
‘company, excepting one perfon, who imagined to have heard
a crackling noife, fomething like that which is produced by
{mall wood when burning. But about ten minttes after the
difappearance of the meteor, and when we were juft going to
retire from the terrace, we heard a rumbling noife, as if it were
of thunder at a great diftance, which, to all probability, was
the report of the meteor’s explofion and it may be naturally
imagined that this explofion happened when the meteor parted:
into {mall bodies, wiz. at about the middle of its: track.
Now if that noife was really the report of the explofion
which happened in the abovementioned place, the diftance,
altitude, courfe, and other particulars relating to. this meteor,
mutt be very nearly as exprefled in the following lift; they
being calculated with mathematical accuracy, upon the pre-
ceding particulars; and upon the fuppofition that found travels
1150 feet per fecond. But if the noife we heard was not that
‘of the meteor’s explofion, then the following calculations muft
‘be confidered as quite ufelefs and erroneous.
1 Diftancé
Meteor cbferved Aug. 18, 1783. Vit
Diftance of the meteor from Windfor Caftle 130 miles.
Length of the path it defcribed in the heavens 550 miles.
Diameter of the luminous body when it came out of
the clouds 7 1070 yards.
Its height above the furface of the Earth 56% miles.
The explofion muft have happened perpendicularly over
Lincolnfhire,
T. CavaLto.
X. An
Schytasod
eet Account of the Meceors of the 18th of Augutt and 4th of
“‘Otober, 1783. By Alex. Aubert, E/g. FR. S. and S.A.
‘Read Jan. 15, 1784.
: AVING been fortunate enough to fee both the Meteors,
i of the 18th of Auguft and-of the 4th of Odtober laft, I
‘think it my duty to communicate the obfervations I made upon
‘them to the Royal Society. We are in general fo little ac-
‘quainted with thefe phenomena, that too many accounts of
them cannot be colleéted, in order to enable us to form fome
idea of their nature, path, magnitude, .and diftance from the
earth. It is not to be expected, that an-obferver, in‘the open
air, to whom the appearance ‘comes totally unexpeGed, can
‘give a perfect account of it; but by going afterwards to the
{pot from which he faw it, he may, by the affiftance of the
objeéts about him, and {tome proper inftruments, come near
the truth: I have followed this method ; and it is the refult
thence deduced I have the honour of communicating to the
Society.
Monday the 18th of Auguft had been a very fultry day. At
the time the meteor made its appearance, although the ftars
were bright in the upper part of the heavens, the horizon ‘was
furrounded with a‘hazinefs which did not permit any ftars to
be feen under an altitude of about eight degrees. I was on
horfeback, returning to my Obfervatory at Loampit-hill, near
Deptford, in Kent; my face was turned towards the South
| Wett,
ne
hilos, Trans Vol LXXIW, Tab IV. p. 1/2.
aay pf. f pt | ¥ een a
(LW allo. del } . sick tTS Jo.
Philos. Trans Vol LXXIV. Tab. IV p. 1/2.
= ;
fe
tj
{
'
}
:
Mr. Auzert’s Account of two Meteors. | 143
“Welt. I was at the foot of Lewifham-bridge, when I was much
farprifed at perceiving fuddenly a kind of glimmering light,
refembling faint but quickly repeated flafhes of lightning; foon
after which the light increafed much towards the North Weft;
I turned dire€tly to it, and faw it form into a large luminous
body like ele€trical fire, with a tinge of blue round its edges.
It rofe from the hazy part of the atmofphere (which I have
obferved might be about 8° high), and moved at firft almoft in
a vertical direCtion, changing its fize and figure continually,
having to me all the appearances of fucceflive inflammation,
and not of a folid body; it was fometimes round, at others
oval and oblong, with its longeft diameter in the line of its
motion ; although it had got high enough to be quite out of
the hazy part of the horizon, it was furrounded and accom-
panied in its whole courfe with a kind of whitifh mf or light
vapour. ‘The place from which it rofe was about 38° from
the north towards the weft. After rifing a little way perpen-
dicularly, it made its progrefs in a curve, fo ds to be at the
higheft when it had reached due eaft, at an altitude of about
35°; after which, continuing a few degrees beyond the eatt,
and being about 30° high, it left behind it feveral globules of
various fhapes; the firft which detached itfelf being very fmall,
and the others gradually larger and larger, until the laft was
nearly as large as the remaining preceding body ‘foon after-
“wards they all extinguifhed gradually, like the bright ‘flars of
a fky-rocket, with fome inclination downwards, which ap-
pearance might probably arife from the upper parts of the fepa-
‘rate bodies extinguifhing before’the lower ones. ‘The meteor
was at the brighteft and at the largeft juft before its feparation ;
I eftimated its magnitude or area then to be equivalent to two
full moons. Its light, during its whole courfe, was fo great,
“VoL. LXXIV. Q. ‘that
%
Ti4 Mr. Ausert’s Account He two Meteors, ..
that I could fee every objekt diftincly, and when it was ex=.
tinguifhed the night appeared very dark: I could however fee
by as that it was feventeen minutes after nine: as.
foon as I got to my obfervatory, which might be about ten
minutes afterwards, having compared it with my regulator, F
found it about half a minute too flow for mean time. I think
the whole appearance of the meteor, from its firft rifing out of
the hazy part of the atmofphere to its total extinction, did not:
exceed ten or twelve feconds of time, during which it moved a.
fpace correfponding to about 136° in azimuth. I recollect an.
appearance during its motion, aaa confirms me in the idea.
Ihad of its not being a folid body. In its progrefs it did not
defcribe a curve as regular as might have been expected from.
fuch a body; but feemed to move in fomewhat of a waving:
line. This irregularity in its-courfe was probably owing to.
changes of its figure and fize, occafioned by the train of in-
flammation not running in an even line. I fhould alfo men-.
tion that the meteor appeared extremely near to me, more-
particularly when it was at the higheft; yet from the com-.
parifons made already of obfervations. at {everal diftant places,
we may reafonably judge, that it could not be at lefs than 40.
or 50 miles diftance from-the furface of the earth...
The meteor of Saturday the 4th of O&tcber laft was: of a,
much fhorter duration and path. JF was on horfeback, near-
the ftones, end, in Blackman-Street, Southwark; my face-
was turned northward. I faw, towards the N.N. E. a train,
of fire, refenrbling in its motion a common meteor, vulgarly:
called a falling ftar, but the colour of it was red 5. it originated’
at an altitude of about 25°, and moved quickly in a ftrait line-
eaftward, inclining gradually towards the horizon, {fo as to be,
after_a_courfe of 15° or 20° in azimuth, about 15° above the-
horizon,_
Mr. Ausert’s Account of two Meteors. 115
horizon, when it fpread into a broader train, and growing of a
lighter colour, it terminated by refolving itfelf into a beautiful
oblong body of the brighteft fire, like ele€hiical fire tinged
blue, almoft as large as the moon ; it illuminated the, {treet
and houfes much more than any lightning I have feen ; thofe
who had not a direct view of it, took it for a long flafh of
lightning. Ithink its whole courfe did not exceed 25°, nor
the time of its appearance two or three feconds. It extinguifh-
ed quickly, and left behind it, in its path, a train of very dull
reddifh fire, which continued vilible to my naked eye above
-one minute and a half. The time of night was forty-three mi-
nutes paft fix; it was a fine ftar-light evening, warmer than
the preceding ones; the moon beyond the firft quarter, and
very bright; yet her light was not to be compared to the much
‘greater light of the meteor.
I do not recollect hearing any noife or report, either during
or after the appearance of thefe meteors. ;
London, : :
eG. ries: ALEXANDER AUBERT.
Since I wrote the above account, I have reafon to think I have
_eftimated the altitude of the laft meteor rather too low; fome
of my friends in London, who. had, at the time of its appear-
ance, avery good object of comparifon for its altitude, make
at nearer 30 than 20 degrees.
~
CEES
Poe
XI. Obfervations on a remarkable Meteor feen on the 18th of
Auguft, 1783, communicated in a Letter to Sir Jofeph Banks,
Bart. P.R.S. By William Cooper, D. D. F.R.S. Arch.
deacon of York. 3
Read Jan. 15, 1784.
DEAR SIR Hartlepool, near Stocktony .
Z Aug, 19, 1783.
O perfon could have a better opportunity of difcerning
this awful meteor than myfelf. The weather being, for-
this climate, aftonifhingly hot, my Faurenuert’s thermome-
ter, on a north pofition, and in the open air, baving for feve-
ral days preceding graduated between the hours of ten-o’clock
in the morning and feven o’clock in the evening from 74° to
82°, I fet. out upon a journey to.the fea-fide. The weather
was fultry, the atmofphere hazy, and not a breath of air
ftirring. ‘Towards nine o’clock at night it was fo dark, that I
could ‘{carcely difcern the hedges, road, or even the horfes
heads. As. we proceeded; I obferved-to my attendants, that
there was fomething fingularly ftriking in the appearance of the.
night, not merely from its ftillnefs and darknefs, but from the
fulphureous vapours which feemed to furround us on every fide...
In the midit of this gloom, and on an inftant, a brilliant tre-
mulous light appeared to the N. W. by N. At the firft it
feemed ftationary ; but in a {mall fpace of time it burft from its
pofition, and took its courfe to the 8, E, by E. It pafled di-.
recily..
~ Dr. Coorer’s Objervations on the Meteor of Aug. 18,1783. 119
re€tly over our heads with a buzzing noife, feemingly at the
height of fixty yards. Its tail, as far as the eye could form any
judgement, was about eight or ten yardsin length. At laft,
this wonderful meteor divided into feveral glowing parts or
balls of fire, the chief part ftill remaining in its full {plendor.
Soon after this I heard two great explofions, each equal to the
report of a canon carrying a nine-pound ball. During its
awful progrefs, the whole of the atmofphere, as far as I could
difcern, was. perfe€tly. illuminated with the moft beautifully
vivid light I ever remember to have feen. The horfes on which
we rode fhrunk with fear; and fome people whom we met upon
the road declared their confternation in the moft expreffive
terms.
Lhave the honor-to be, Se. .
WILLIAM Cooper...
Lar
NIL Aa Account of the Meteor of the 182h of Auguft, 1 783. In
_a Letter from Richard Lovell Edgeworth, E/g. FR. S: to
‘Sir Jofeph Banks, Bart, P.R.S. a
Read Jan. 15, 1784.
MEAR SIR, ‘Edgeworthflown, Mullingar, Ireland.
T half paft nine in the evening of the 18th of Auguft, f
faw the meteor which has been obierved in fo many
different places. |
ts fize appeared to be about one third of the moon’s diame-
ter; and it moved from the noth with an equable velocity, at
an elevation of ten or twelve degrees, and in a line parallel to
the horizon.
It was vilible during ten or fifteen feconds, and feemed to be
of a parabolic figure, with a luminous tail, twenty or five and
twenty of its diameters in length.
It exhibited the moft vivid colours; the foremoft part being
of the brighteft blue, followed by different’ fhades of red.
Twice during its flight it was eclipfed or extinguifhed, not
gradually, but at once, immerging and emerging with undi-
minifhed luftre.
I fhall not venture to trouble you with any conjectures upon
the nature of this phenomenon, as it is probable, that the
fubje&t has been fully difcuffed long before this time by your
friends in London. Iam, Gc.
Sept.s, 1783. RicHARD LovELL EDGEWORTH.
TRO
-
“ig
Pivot i
il. Experiments on Air. By Henry Cavendith,. E/g.
FB. ie 5S, ep Ss. A.
Read’ Jan. rs, 1784.
es following experiments were made principally with a:
view to find out the caufe of the diminution which
éommon air is weil known to fuffer by. all the various ways in:
which it is phlogifticated, and to ditcover what: becomes of the:
air thus. loft or condenfed ; and as. they feem: not only te de-
termine this point, but. alfo to throw great lisht.on the con-
ftitution and. manner of production of dephlogifticated air, F
hope they may be not. unworthy the acceptance of. this. fo--
giety. |
Many gentlemen have fuppofed that fixed air is either geme--
rated or feparated from atmofpheric air by phlogiftication, and:
that the obferved diminution is owing to- this caufe 3: my firft
experiments therefore were made in order to afcertain whether
any fixed air is really produced thereby... Now, it muft. be ob-
ferved, that as al) animal and vegetable fubflances contain fixed.
air, and yield it by burning, diftillation, or putrefaction, no-
thing can be concluded. from experiments in which the air is-
phlogifticated by them. ‘The only methods I know, which are-
not liable to. ebjeétion, are by the calcination of metals, the-
burning of fulphar or phofphorus, the mixture of nitrous.air,,
and the explofion of inflammable air. Perhaps it may: be fup-
pofed, that lought to add to thefe the electric. {park ;. but E
: think,
120 Mr. Cavenpisn’s Experiments on Air.
think it much moft likely, that the phlogiftication of the air, and
production of fixed air, in this procefs, is owing to the burning
of fome inflammable matter in the apparatus. When the
{park 1s taken from a folution of teurnfel, the burning of the
tournfol may produce this effet; when it is taken from lime-
water, the burning of fome foulnefs adhering to the tube, or
perhaps of fome inflammable matter contained in the lime,
may have the fame effet; and when quickfilver or metallic
knobs are ufed, the-calcination of them may contribute to the
phlogiftication of the air, though not to the produGtion of fixed
aire
There is no reafon to think that any fixed air is produced by
the firft method of phlogiftication. Dr. PrirsTLEY never found
lime-water to become turbid by the calcination of metals over
it*: Mr. Lavoisier alfo found only a very flight and {carce
perceptible turbid appearance, without any precipitation, to take
place when lime-water was fhaken in a glafs veflel full of the
air in which lead had been calcined; and even this {mall dimi-
nution of tranfparency in the lime-water might very likely
arife, not from fixed air, but only from its being fouled by par-
ticles of the calcined metal, which we are told adhered in fome
places to the glafs. This want of turbidity has been attributed
to the fixed air uniting to the metallic calx, in preference to the
lime; but there is no reafon for fuppofing that the calx con-
tained any fixed air; for I do not knew that anyone has ex-
tracted it from calces prepared in this manner; and though
moft metallic calces prepared over the fire, or by long expofure
to the atmofphere, where they are:im contact with fixed air,
contain that fubftance, it-by no means follows that they muft
* Experiments on Air, vol. I. .p. 137.
-de
Mr. Cavenpisu’s Experiments on Airs = at
do fo when prepared by methods in which they are not in con-
ta with it.
Dr. PriesTLey alfo obferved, that ginclbdnds fouled by the
addition of lead or tin, depofits a powder by agitation and expo-
fure to the air, which confifts in great meafure of the calx of
the imperfect metal. He found too fome powder of this kind
to contain fixed air* 3 but it is by no means clear that this air
was produced by the phlogiftication of the air in which the
quickfilver was fhaken; as the powder was not prepared on
purpofe, but was procured from quickfilver fouled by having
been ufed in various experiments, and may therefore have con-
tained other impurities befidesthe metallic calces.
I never heard of any fixed air being produced by’ the burning
of fulphur or phofphorus; but it has been afferted, and com-
monly believed, that lime water is rendered cloudy by a mix-
ture of common and nitrous air; which, if true, would be a
convincing proof that on mixing thofe two fubftances fome
fixed air is either generated or feparated; I therefore examined
this carefully. Now it muft be obferved, that-as common air
ufually contains a little fixed air, which is no effential part of
it, but is eafily feparated by lime-water 3 and as nitrous air may
alfo contain fixed air, either if the metal from which it is pro-
cured be rufty, or 1f the water of the veflel in’ which it is
caught contain calcareous earth, fufpended by fixedair,- as moft
waters do, it is proper firft-to free both airs from it by préeviouf
Jy wafhing them with lime water +. Now 1 found, by repeat-
| | , ed
ok
Exper. in Nat. Phil. vol. I. p. 144.
¢ Though fixed air is abforbed in confiderable quantity by w ater, « as I fhewed
in Phil. Tranf. vol, LYI. yet it is not eafy to deprive common air of all the fixed
Vor, LXXIV, R air
(422 Mr, Cavenvisn’s Experiments on Airs
ed experiments, thatif the lime water was clean, and the the:
airs were previoufly wathed with that fubftance, not the: leaft
cloud) was produced, either immediately on mixing them,.or
on fuffering them to. ftand- upwards of an hour, though i It .ap=
eared. by. ihe thick clouds which’ ‘were produced in the ‘lime
water, by breathing: through it after the experiment was finifh=
ed, that it was more than fufficient'to faturate:the acid formed
by the:decom:pofitien; of, the nitrous air, and confequently that
if, any,, fixed air; had been produced,: it muft have become: vifi~
ble.,.,Once indeed I found a {mall cloud to be formed on the
furface, after the mixture had ftood,a few minutes. ; In this ex-
periment the lime water was not quite clean’; but’ whether the
cloud was owing to this, circumftance, or to the air’s haa not
been properly wafhed, I cannot pretend to fay.) i) - | 9
Neither does any fixed air feem to be produced by the ae
fion of the inflammable air obtained from’ metals, with either
common or dephlogifticated air. , This I tried by putting alittle.
lime- water into-a glafs globe fitted, with a brafs cock,i fo.as to
make it air tight, and/an apparatus for firing air by eleétricity.:
This. globe was exhaufted by an; air-pump, and the twoiairs,
which had been previoufly wafhed with lime-water, let:in, and:
fuffered to remain fome time, to fhew whether they, would
affect the lime-water, and then fired by electricity. The event
was, that not the leaft cloud was produced in the lime-water,
when the inflammable air was mixed with common air, and
air contained in it by means of water. On fhaking a mixture of ten parts of com-
mon air, and one of fixed air, with more than an equal bulk of diftilled water,
not more than half of the fixed air was abforbed, and on transferring the air into
freth diftilled water only half the remainder was abforbed, as appeared by the di-
minution which it fill fuffered on adding lime water.
only
_ Mr. Cavennisu’s Experiments of) Air. 523
eply:a very flight one, or rather dithinution of tranfparency,
when it was combined with’ dephlogif{ticated) air. This; how-
ever, feemed not to be produced by fixed’ain;::asat appeared ins
{tantly after the explofion, and did not imcreafe sony ftanding,
and,!was -{pread uniformly through ‘the -liquor ; whereas-if:it
had been owing:to fixed air, 1t would: havetaken up: fome’ {hort
time before it appeared, and would have begum firft at the fur
face, as was the; cafe in the abovementioned experiment’ with
nitrous air. «What it was really owing ‘to! J cannot pretend
today ; but ifi it did: proceed :from fixed air it: would thew that
enly. an exceéflively; minute quantity was produced *. On -the
Whole, thoughrityis:not improbable that fixed air may be gene~
fated in fome:chymical procefies;, yet it: feems>certain that it/:is
not the general.effe& of phlogifiscating air, and that the dimi-
nution-of-common air is by no means owing fo athe: generation
endeparation.of fixed: air frombitaooig sly botrotlinols 41
As there feemed great. reafon|to think, aie Dr. Rishiaga $
eipeiiiments) that the nutrous;andavitriolic agids, were; conver-
tibleanto;dephiogifticated air, tmed whether,-the ,dephlogifi-
cated «part of -coimmon)-ait/ «ight not, by, phlogiftication,. be
changed intornitrous! or; vitriolic: acid... For this purpofe f-im-=
preguated fome milk of lime with the cen of burning fulph ur,
byisputting- Aditle: of; itsinto alarge glafs regeiver, and burning,
fiphur thereity); staking icate;to; keep the mouth ofthe receiver
fopt till-the fumes were} alli abforbed ; after which--the “aar Of
the receiver .was; changed;-dnd Imore) {ulphur, burnt, in} it.as
before, and the procefs repeated till. 122 grains of fulphur; were
confumed.» |The milk of lime was then filtered and, évaporated,
but cit yielded ho!-nitrous (alt, nor any other fubftance-except
felemite;' fo that no fenfible. quantity. of; the! air, was, changed
o* Dr. Prisraey alfo found no fixed.airtg be. producedcby the explofion(jof; ing
fétimable‘and common air, Vol. V, p. 124.
zi Riz into
Ne OR aN? t
re ER tf tied 7»
* a m
bie Mga WPT ati Ae
424. Mr, Cavenvisn’s Experiments on Air.
into nitrous acid. It muft be obferved, that as the vitriolic
acid produced by the burning fulphur is changed by its union
with the lime into felenite, which is very little foluble in
water, a very {mall quantity of nitrous falt, or any other fub-
ftance which is foluble in water, would have been perceived.
I alfo tried whether any nitrous acid was produced by phlo-
gifticating common air with liver of fulphur; for this purpofe
I made a folution of flowers of fulphur by boiling it with lime,
and’ put a littie of it into a large receiver, and fhook it fres
quently, changing now and then the air, till the yellow co-
lour of the folution was quite gone; a fign that all the fulphur
was, by the lofs of its phlogifton, turned into vitriolic acid, and
united to the lime, or precipitated ; the liquor was then filtered
and evaporated, but it yielded not the leaft nitrous falt.
The experiment was repeated in nearly the fame manner
with dephlogifticated air procured from. red precipitate ; but
not the leaft nitrous acid was obtained.’
It is well known that common felenite is very little foluble
in water ; whereas that procured in the two. laft experiments
was very foluble, and even cryftallized readily, and was in-
tenfely bitter; this however appeared to be owing merely’ to
the acid with which it was formed being very much phlogif-
ticated; for on evaporating it to drynefs, and expofing it to the
air fora few days, it became much lefs foluble, fo that on
adding water to it not much diffolved; and by repeating this
procefs once or twice, it feemed to become not more foluble than
{elenite made in the common manner.
This folubility of the felenite caufed fome trouble.in trying
the experiment ; for while it continued much foluble it would
have been impoffible to have diftinguithed ‘a {mall mixture of
nitrous falt; but by the abovementioned procefs I was able to
diftinguifh:
, BOS
Mr. Cavennisn’s Experiments on Air. 126
diftinguifh as fmall a proportion as if the felenite _ been ori-~
ginally no more foluble than ufual.
The nature of the neutral {alts made with the hilseiticonl
vitriolic and nitrous acids has not been much examined by the
chymifts, though it {eems well worth their attention ; and it
is likely that many befides the foregoing may differ remarkably
- from thofe made with the fame acids in their common ftate,
- Nitre formed with the phlogifticated nitrous acid has been
found to differ confiderably from common nitre, as well as a.
Polychreft from vitriolated tartar.
In order to try whether any vitriolic acid was produced by
the phlogiftication of air, 1 impregnated fifty ounces of diftilled’
water with the fumes produced on mixing fifty-two ounce
meafures of nitrous air with a quantity of common air fufficient
to decompound it. This was done by filling a bottle with
fome of this water, and inverting it into a bafon-of the fame,
and then, by a fyphon, letting in as much nitrous air as filled
it half-full; after which common air was-added flowly by the
fame fyphon, till all the nitrous air was decompounded. When’
this was done, the diftilled water was further impregnated in’
the fame manner till the whole of the abovementioned quan-
tity of nitrous air was employed. This impregnated water,,
which was very fenfibly acid to the tafte, was diftilled in a glafs:
retort. The firft runnings were very acid, and {melt pun-
gent, being nitrous acid much phlogifticated ; what came next
had no fenfible tafte or fmell; but the laft runnings were very
acid, and confifted of nitrous acid not phlogifticated.' Scarce
any fediment was left behind. Thefe different parcels of dif-
tilled liquor were then exaétly faturated with falt of tartar, and:
evaporated; they yielded 87% grains of nite, which, as faras’
I’could perceive, was diihdned with vitriolated tartar or any
E other
>
>
5
126 Mp. CAVENDISH’s Experiments, on ae. |
other: fabftance,: and confequently: no, fenhb! e quantity of the
‘common air with a the nitrous air was! mixed: was tained
into.-vitriolic-acid: - feo edad ferirrert: acid Joo ae
‘It-appears, from his ae. that nitrous air ‘contdins as
6 et ds, as 23 times its, weight of faltpetre ;. for fifty-two,
euncé: meafures of nitrous air weigh 32 grains, and, as,\wag
before faid, yield-as; much acid-as is containedin 842 grains, of
‘faltpetre; 40 thatthe acid in nitrous air isin a remarkably
. Coficentrated -{tate, and I believe more than-PF; times as muh iho:
_as the ftrongeft {pirit of nitre ever prepared: 2.4} [
-Having new. mentioned the unfuccefsful attempts | Boies ito
‘find out what becomes ofthe air lott by phlogiitication, ‘TI pro=
ceed to fome experiments, which ferve really to: explainsthe
mattefe) oi: 00 ; og hiss e
‘alu, Dr. PriesTieEy’s lat salons fe expen tates 18 dae
an experiment ef Mr, WaARLTIRE’s, in whichat.ts faid)that, on
firstig a mixture-of common and inflammable,air by eleCtiicity.
10, & Clefe: copper veflel holding about three pints, a lofs of weight’
was/aliv ays{perceived, on an-average about two) grains,, though}
‘the jveflel- was flopped in fuch a;manner that no; aincould efcape;
by, the explofion.;.-It is alfo related, that on wepeating the -ex-
periment in. glafs.veflels, the 'infide of the glafs,, though clean:
and) dry before, immediately - becamie’. dewy’s which, confimed -
an opinion he had ‘long entertained,that conimon, air depolits;
its moifture -by phlogiftication.’ As the latter,,experiment ‘feem-
edhlikely, to throw great light »on the fubject/L had. an jview;, Ag
thought itiwell worth examiting more clofelys{\)\Tche frit ex-,
periment alfo, if there, was}no miftake in it, -would;be very; exr;
traordinary and curious; jbyt. it, did). not fucceed., with mels/, for;
‘though the -veflel 1. ufed held, more than Mr. | WARLTIRE? S59
namely, 24,000) grdins)jof -w ater, aind though the experiment!
7 was
6
Mr. Cavenpisn’s Experiments on Air. 124
was repeated'feveral times with different ‘proportions of ¢om-
mon and inflammable air, I could: never perceive a lofs of .
weight of moré than one-fifth of a grain, and’ commonly
none at all. It muft be obferved, however, that though ‘there
svere fome of thé experiments in which it feemed’to diminith .
a little in weight,. there were none in which it increafed *, *
In all the experiments, the infide of the glafs:elobe became |
dewy, as obferved’ by Mri War itire; but not the leaft footy
matter could -be: perceived... Care was! takenin “all of them ‘ta
find how much 'the*air was? diminifhed by the explofion, and —
to obferve its teft.. The refultis as follows: the bulk of the -
inflammable air being exprefied in decimals of the common :
air, , tat
Commen air.|Inflammable Diminution. Air remain- fTeft of, this} Standard. ©
aire: See ‘jing after-thelair’ in firft} ©
‘ey explofion. method.
ic ale SAL CRN GR ale bie Et ind fale ol Sp ,0
OW] pis W,05 PU) 31,6420. $l Iam it -jofsii 0
~! ites Tay 5706) | 5047 i bont,.95a 5066 29
ee Ee pa One Hh) Lon) | OOF AGIs
Baa ls WAG ten, 855 1 4320. 927
3206 7294 , i G12 ,048° 25
' In thefe experiments the-inflammable air was procured from >
zinc, \as it was in-all my experiments, except. where otherwife
exprefled: but 1 made two more experiments,’ to try whether -
there was. any difference between the air from zinc and that
from iron, the quantity of inflammable air-being.the fame in. ;
both, namely, 0,331 of the common; but I could not findany. |
@ifférence tobe depended on between the, two kinds of air,
~* Dr. PRiEsTLey, I am. informed, has fince found the experiment not: to
fecceed, if LLY
either -
128 Mr, Cavennisn's Experiments on Air.
either in the diminution. which, they fuffered by the explofion,
or the teft of the burnt air. |
From the fourth experiment it appears, that 423 meafures of
inflammable air are nearly fufficient to completely phlogifticate
1000 of common air; and that the bulk of the air remaining
after the explofion is then very little more than four-fifths of
the common air employed; fo that as common air cannot be
reduced to a much lefs bulk than that by any method of phlo-
giftication, we may fafely conclude, that when they are mixed
in this proportion, and exploded, almoft all the inflammable
air, and about one-fifth part of the common air, lofe their
elafticity, and ate condenfed into the dew which lines the
glafs.
The better to examine the nature of this dew, 506600 grain
meafures of inflammable air were burnt with about 24 times
that quantity of common air, and the burnt air made fo pafs
through a glafs cylinder eight feet long and three-quarters of
an inch in diameter, in order to depofit the dew. The two
airs were conveyed flowly-into this cylinder by feparate cop-
per pipes, paffing through a brafs plate which {topped up the
end of the cylinder; and as neither inflammable nor common
air can burn by themfelves, there was no danger of the flame
{preading into, the magazines from which théy were conveyed.
Each of thefé magazines confifted of a large tin veflél, in-
verted into another: veflel juft big enough to! receive ‘it. The
inner: veffel communicated with the copper pipe, and the air
was forced out of it by pouring water ifito the outer veffel'; —
and in order that the quantity of eommoniair expelled ‘thould
be 2! times that’ of the inflammable, the water was let into
the outer veflels by two holes in, the bottom of the fame tin’
pally the hole which conveyed the water into that veffel in
which
Mr, Cavenvisn’s Experiments on Air. 1297
which the common air was confined being 23 times as big: as.
the other.
In trying the experiment, the magazines belag firft filled
with their refpective airs, the glafs cylinder was taken off, and
water let, by the two holes, into the outer veffels, till the airs
began to iffue from the ends of the copper pipes; they were
then fet on fire by a candle, and the cylinder put on again in
its place. By this means upwards of 135 grains of water were
condenfed in the cylinder, which had no tafte nor {mell, and
which left no fenfible fediment when evaporated to drynefs ;
neither did it yield any pungent fmell during the evaporation 5 5
in fhort, it feemed pure water. |
In my firft experiment, the evlindstt near that part. where
the air was fired was a little tinged with footy matter, but
very flightly fo; and that little feemed to proceed from the
putty with which the apparatus was luted, and which was
heated by the flame; for in another experiment, in which it
was contrived fo that the luting fhould not be much ° heated,
fcarce any footy tinge could be perceived.
By the experiments with the globe it appeared, that) when
inflammable and common air are exploded:in a proper propor-
tion, almoft all the inflammable air, and near one-fifth of the
common air, lofe thew elaflicity, and are condenfed into dew.
And by this experiment it appears, that this dew is plan wa-
ter, and confequently that almoft all the inflammable air, and
about one-fifth of the common air, afe turned into pure water.
: In order to examine the nature of the:matter condenfed on
firmg a mixture of dephlogifticated and inflammable air, J took
a glafs globe, holding 8800 grain meafures, furnifhed with a
brafs cock and an apparatus for firing air by electricity, ‘This
globe was well exhaufted by an air-pump, and then filled with
: Wer. LXXIV, S a mixture
‘
‘130 Mr. Cavenpisu’s Experiments.on Air.
a mixture of inflammable and dephlogifticated air, by thutting
the cock, faftening a bent glafs tube to its mouth, ‘and letting
up the end of it into a glats jar inverted into water, and con-
taining a mixture of 19500 grain meatures of dephlogitticated
air, and 37000 of inflammable;. fo that, upon opening the
cock, fome of this mixed air rufhed through the bent tube, and
filled the globe *. ‘The cock was then ihut, and the included
air fired by ele&tricity, by which means almoft all of it loft its
elafticity. The cock was then again opened, fo as to let in
more of the fame air, to fupply the place of that deftroyed by
the explofion, which was again fired, and the operation conti-
nued till almoft the whole of the mixture was let into the
globe and exploded. By this means, though the globe held
not more than the fixth part of the mixture, almoft the whole
of it was exploded therein, without any frefh exhauftion of
the globe. )
As I was defirous to try the quantity and teft of this burnt
air, without letting any water into the globe, which would
have prevented my examining the nature of the condenfed
matter, I took a larger globe, furnifhed alfo with a ftop cock,
exhaufted it by an air-pump, and ferewed it on upon the cock
of the former globe; upon which, by opening both cocks, the
air rufhed out of the {maller globe into the larger, till it be-
came of equal denfity im both; then, by fhutting the cock of
the larger globe, unfcrewing it again from the former, and
opening it under water, I was enabled to find the quantity of
the burnt air in it; and confequently,, as the proportion
which the contents of the two globes bore to each other was
* In order to prevent any water from getting into this tube, while dipped
under water to let it up into the glafs jar, a bit of wax was was ftuck upon the
end of it, which was rubbed off when raifed above the furface of the water.
_ known,
Mr. CAVENDIsH’s Experiments on Air. I 31,
known, could tell the quantity of burnt air in the {mall globe
before the communication was made between them. By this
means the whole quantity of the burnt air was found to be
2950 grain meafures; its {tandard was 1,85. ;
The liquor condenied in the globe, in weight about on
grains, was fenfibly acid to the tafte, and by faturation with
fixed alkali, and evaporation, yielded near two grains of nitre;
fo that it confifted of water united to a {mall quantity of ni-
trous acid. No footy matter was depofited in the globe. The
dephlogifticated air ufed in this experiment was procured from.
red precipitate, that is, from a folution of quickfilver in fpirit
of nitre diftilled till it acquires a red colour.
Asit was fufpected, that the acid contained in the condened
liquor was no effential part of the dephlogifticated air, but was
owing to fome acid vapour which came over in making it and had
not been abforbed by the water, the experiment was repeated in
the fame manner, with fome more of the fame air, which had
been previoufly wafhed with water, by keeping it a day or two
in a bottle with fome water, and fhaking it frequently ; whereas
that ufed in the preceding experiment had never pafied through
Water, except in preparing it. ‘The condenfed liquor was ftill
acid. ;
The experiment was alfo repeated with dephlogifticated air,
procured from red lead by means of oil of vitriol; the liquor
condenfed was acid, but by an accident I was prevented from
determining the nature of the acid.
I alfo procured fome dephlogifticated air from the leaves of
plants, in the manner of Doctors Incennousz and PRIESTLEY,
and exploded it with inflammable air as before; the condenfed
liquor ftill continued acid, and of the nitrous kind,
S 2 | 3 Tn
132 Mr. Cavennisn’s Enperiments on Air.
In all thefe experiments the proportion of inflammable air
was fuch, that the burnt air was not much phlogiiticated; and
it was obferved, that the lefs phlogifticated it was, the more:
acid was the condenfed liquor. I therefore made another expe=
riment, with fome more of the fame air from plants, in which
the proportion of inflammable air was greater, fo that the
burnt air was almoft completely. phlogifticated, its ftandard
being 3. ‘The condenfed liquor was then not at all acid, but:
feemed pure water:, fo that it appears, that with this kind of
dephlogifticated air, the condentfed liquor is not at all acid,
when the two airs are mixed in fuch a proportion that the
burnt air is almoft completely phlogifticated, but 1s confiderably
fo when it is not much phlogifticated.
In order to fee whether the fame thing would obtain with:
air procured from red precipitate, I made two more experi-
ments with that kind of air, the air in both being taken from:
the fame bottle, and the experiment tried in the fame manner,,
except that the proportions of inflammable air were different...
In the firft, m which the burnt air was almoft completely
phlogifticated, the condenfed liquor was not at all acid. In.
the fecond, in which its ftandard was 1,86, that 1s, not much.
phlogifticated, it was confiderably acid; fo that with this.air,
as well as with that from plants, the condenfed liquor contains,.
or is entirely free from, acid, according as the burnt air is lefs:
or more phlogifticated ; and there can be little doubt but that
the fame rule obtains with any other kind of dephlogifticated:
air.
In order to fee whether the acid, formed by the explofion of
dephlogifticated air obtained by means of the vitriolic acid,
would alfo be of the nitrous kind, I procured fome air from.
turbith mineral, and exploded it with inflammable: air, the
propor-
Mr. Cavenvisn’s Experiments on Air. 133:
proportion being {uch that the burnt air was not much phlo-
gifticated. ‘The condenfed liquor manifefted an acidity, which
appeared, by faturation with a folution of falt of tartar, to be
of the nitrous kind ; and it was found, by the addition of fome
terra ponderefa falita, to contain little or no vitriolic acid.
- When inflammable air was exploded with common air, in
fuch a proportion that the ftandard of the burnt air was about’
., the condenfed liquor was not in the leaft acid. There is.
no difference, however, in this refpect between common air,
and dephiogifticated air mixed with phlogifticated in fuch a
proportion as to reduce it to the ftandard of common air; for
fome dephlogifticated air from red precipitate, being reduced
to this ftandard by the addition of perfectly phlogifticated air,
and then exploded with the fame proportion of inflammable
air as the common air was in the foregoing experiment, the
condenfed liquor was not in the leaft acid. | 7
From the foregoing experiments it appears, that when a:
mixture of inflammable and dephlogifticated air is exploded in
fuch proportion that the burnt air is not much phlogifticated,
the condenfed liquor contains a little acid, which is always of
the nitrous kind, whatever fubftance the dephlogifticated air is.
procured from; but if the proportion be fuch that the burnt
air is almoft entirely phlogifticated, the condenfed liquor is:
not at all acid, but feems pure water, without any addition
whatever; andas, when they are mixed in that proportion,
very little air remains after the explofion, almoft the whole:
being condenfed, it follows, that almoft the whole of the in-
flammable and dephlogifticated air is converted into pure wa-
ter. It is not eafy, indeed, to determine from thefe experi-
ments what proportion the burnt air, remaining after the explo-
fons, bore to the dephlogifticated air employed, as neither the:
Zo: {mall
I 34 Mr, Cavenpisn’s Experiments on Air.
{mall tior the large’ globe could be perfeétly exhaufted of air,
and there was no: faying with exactnefs what quantity was left
in them; but in moft of them, after allowing for this uncer=.
tainty, the true quantity of burnt air feemed not more than
7th of the dephlogifticated air employed, or 7th of the mix-.
ture, It feems, however, unnecefiary to determine this point
exactly, as the quantity is fo fmall, that there can be little doubt:
but that it proceeds only from the impurities mixed with the
dephlogifticated and inflammable air, and confequently that,
if thofe airs could be obtained perfeétly pure, the whole would
be condenfed.
With refpec&t to common air, and dephlogifticated air re-
duced by the addition of phlogifticated air to the ftandard
~ of common air, the cafe is different; as the liquor condenfed
in exploding them with inflammable air, I believe I may fay in
any proportion, is notat all acid; perhaps, becaute if they are
mixed in fuch a proportion as that the burnt air is not much
phlogifticated, the explofion is too weak, and not accompanied
with fufficient heat.
All the foregoing experiments, on the explofion of inflam-
mable air with common and dephlogifticated airs, except thofe
which relate to the caufe of the acid found in the water, were
made in the fummer of the year 1781, and were mentioned -
by me to Dr. PrizsrLtey, who in confequence of it made
fome experiments of the fame kind, as he relates in a paper
printed in the preceding volume of: the Tranfactions.. During
the laft fummer alfo, a friend of mine gave fome account of
them to M. Lavoisier, as well as of the conclufion drawn
from them, that dephlogifticated air is only water deprived of
phlogifton ; but at that time fo far was M. Lavotsizr from
thinking any fuch opinion warranted, that, till he was pre=)
5 vailed
Mr. Cavennisu’s Experiments on Air. 13%
vailed upon to repeat the experiment himfelf, he found fome
difficulty in believing that nearly the whole of the two airs
could be converted into water. It is remarkable, that neither
of thefe gentlemen found any acid in the water produced by
the combuftion ; which might proceed from the latter having
burnt the two airs in a different manner from what I did; and
from the former having ufed a different kind of inflammable air,
namely, that trom charcoal aud perhaps having ufed a greater
proportion of it.
Before I enter into the caufe of thefe phenomena, it will be
proper to take notice, that phlogifticated air appears to be no-
thing elfe than the nitrous acid united to phlogifton ; for when
mitre is deflagrated with charcoal, the acid is almoft entirely
converted into this kind of air... That the acid 1s entirely con-
verted into air, appears from the common procefs for making
what is called clyflus of ‘nitres for if the nitre and charéoal
are dry, {carcecany thing is found in'the veflels prepared for
condenfing the fumes; but if they are moift.a little liquor jis
collected, which is nothing but the water contained in the ma-
terials, impregnated with, a little volatile alkali, proceeding in
all probability from the imperfectly burnt charcoal, and a little
fixed alkali, confiftng’ of fome of the alkalized nitre carried
over by the heatand:watery vapours. As far’as. I can: perceive
too; at’ prefent; thé air into which much the, greateft part of
the acid is converted, differs in no refpect: from, common air
phlogifticated. | A {mall part of the acid, however, is turned into
nitrous air, and the whole is. mixed with a good deal of fixed,
and perhaps a little anflammable, ant both proscading from. the
Pharccieth | :
Ttis well known, that the nitrous ‘acid. is alfo eke Hi ie
eilosdasaioti into nitrous, airy, in which refpect, there feems a
| confiderable
\ m6 Mr. Cavenpisn’s Experiments on Air.
confidérable analogy between that and the vitriolic acid; for
the vitriolic acid, when united to a {maller proportion of phlo-
gifton, forms thé volatile fulphureous acid and vitriolic acid air,
both of which, by expofure to the atmofphere, lofe their phlo-
gifton, though not very faft, and are turned back into vitriolic
acid; but, when united to a gréater proportion of phlogifton, it
forms fulphur, which fhews no figns of acidity, unlefs a {mall
degree of affinity to alkalies can be called fo, and in which the
phlogifton is more ftrongly adherent, fo that it does not fly off
when expofed to the air, unlefs aflifted by a heat fufficient to
fet it on fire. In like manner the nitrous acid, united to a cer-
tain quantity of phlogifton, forms nitrous fumes and nitrous
air, which readily quit their phlogifton to common air; but
when united to a different, in all probability a larger quantity,
it forms phlogifticated air, which fhews no: figns of acidity,
and is ftill lefs difpofed to part with its phlogifton than fulphur.
This being premifed, there feem two ways by which the
phanomena of the acid found in the condenfed liquor may be
explaineds firft, by fuppoimg that dephlogifticated. air con-
tains a little nitrous acid which enters into it as one of its
component parts, and that this acid, when the inflammable
air is in a fufficient proportion, unites to the phlogifton, and
is turned into phlogifticated air, but does not when the inflame
mable air is in too fmall a proportion; and, fecondly, by fups
pofing that there is fo nitrous acid mixed with, or entering
into the compofition ef, dephlogifticated air, but that, when
this air is in a fufficient proportion, part of the phlogifticated
air with which it is debafed is, by the ftrong affinity of phlo-
gifton to dephlogifticated air, deprived of its phlogifton and
turned into nitrous acid; whereas, when the dephlogifticated
air is not more tha fufficient to.confume the inflammable air,
none
Mr. Caven DISH’s Experiments o on i Air: - 137
‘none then 3 remains to deprive the a eas air 5 its phio-
Bifton, and turn itinto acid. oe ene
If the latter explanation be true, T hie we mutt allow
‘that dephlogifticated air is in reality nothing but dephlopifti-
cated water, or water deprived of its phlogifton ; or; in’ other
~Svords, that water confifts of dephlogifticated air* united to
phlogifton ; and that inflammable air is either pure phlogifton,
‘as Dr. PkirstLey and Mr. Kirwan fuppofe, or elfe water
united to phlogifton*; fince, according to this fappofition,
thefe two fubftances united together form pure water. On the
‘other hand, if the firft explanation be true, we muft fappofe
that dephlogifticated air confifts of water ‘united to ‘a’ little
‘nitrous acid and deprived of its phlogifton; but ftill the ni-
trous acid in it muft make only a very {mall part of the whole,
* Hither of thefe fuppofitions will agtee equally well with the following expe-
iments} but the latter féems to me much the moftlikely. What’ principally
makes me think fo is, that commoa or dephlogifticated air do not abforb phlo-
gifton from inflammable air, | uinlefs aflifted by a red heat, whereas they abforb
the phlogifton of nitrous air, liver of fulphur, and many other fubftances, with-
out that affiftance ; and it feems inexplicable, that they-fhould refufe to unite to
‘pure phlogiftos, when they are able to extract it from fubftances to which it has an
affinity ; that is, that they fhould overcome the affinity of phlogifton to other
fubftances, and extrac& it from them, when they will not even unite to it when
prefented to them, On the other hand, I know no experiment which fhews
inflammable air to be pure phlogifton rather than an union of it with water,
unlefs it be Dr. Prizsriey’s éxperiment of expelling inflammable air from iron
by heat alone. 1 am not fufficiently acquainted with the circumftahces of that
experiment to argue with certainty about it; but I think it much more’likely,
that the inflammable air was formed by the union of the phiogifton of the iron
filings with the water difperfed among them, or contained i in the retort or other
vetfe! in which it was heated; and in all probability this was the caufe of the
Aeparation of the phlogifton, as iroh feems not difpofed to part with its phlo-
gifton by heat alone, without being affifted by the air of fome other fubftance.
Vor. LXXIV, g2 as
- 33 Mr. CAVENDISH’s Experiments.on Air.
qs it 1s found, that the phlogifticated air, which it is converted
into, is very final in comparifon of - the dephlogifticated ali,
. think the feeond ef thefe explanations feems much the
mot likely 5, as it was. found, that the acid. in: the: -condenfed
Jiquor was, of the nitrous: kind, not only. when the dephlo-
ejfticated air was prepared from: red precipitate, but alfo. when
it was. procured from plants ; or from turbith mineral: and. it
feeems not likely, that air procured from plants, and fill lefs.
likely that.air procured from a folution of AREREHEY in : oil of
wtriol, fhould contain any nitrous.acid. ) *
} Another ftrong argument. in favour of: this opinion | is, ae
dephlogifticated air yields no nitrous. acid when phlogifticated
by liver of fulphur; for if this air contains nitrous acid, and
yields it when phlogifticated by explofion with inflammable ally
it is very extraordinary that it fhould not do fo when palegitte
cated by other means. ; iy
But what forms a ftronger and, I ssinatt almoft' decifive:
argument in favour of this explanation is, that when the de-
phlogifticated ait is very pure, the condenfed liquor is made
much more ftrongly acid by mixing the air to be exploded with
a little phlogifticated air, as appears by the following expe-
riments.
A mixture of 18500 grain meafures of inilanninadlite air with
9750 of dephlogifticated air procured from red precipitate were
exploded in the ufual manner; after which, a mixture of the
fame quantities of the fame dephlogifticated and inflammable
air, with the addition of 2500 of air phlogifticated by iron
filings and fulphur, was treated in the fame manner. The
condenfed liquor, in both experiments, was acid, but that in
the latter evidently more fo, as, appeared alfo by faturating
each of them feparately with marble powder, and precipitating
7 ‘the
Br. Cavenpisn’s Experiminty th Airs ohgg
the earth by fixed alkali, the precipitate of the fecond experi
tent weighing one-fifth of a grain, and that of. the firft
being feveral:times lefs. The ftandard of the burnt air in the
firft experiment was 1,86, and:in the fecond only. 0,9:
oIt muft be’ obferved, that all circumftdnces, «were the
fame in thefe two experiments, except that in thé latter'the
air to be exploded was mixed with fome phlogifticated air, aid
that in confequence the burnt air was more phlogifticated than
in the former ; and from what has been before faid, it appears,
that this latter circumftance ought rather to have made.the
condenfed liquor lefs acid; and yet it was found to be:much
more fo, which fhews ftrongly that it was the ahivaiinies
air which furnifhed the acids ls
As a further confirmation of this point, id two cBliagiathe
tive:experimients' were repeated>with a little variation, namely,
in the firft experiment there was firft let into the globe 1500
of dephlogifticated air, -anditheti the mixture, confifting’ of
12200 of dephlogifticated airand 25900 of inflammable, was let
in at differentitimes as ufual. In the fecond experiment, befides
the 1§00 of dephlogifticated air: fitft Jet in, there was alfo ads
mitted 2500\0f phlogifticated: air; after which» the mixtures
_¢onfifting of the fame quantities.of dephlogifticated and in fame
mable air-as before, was let inasiufual.! “Fhe ¢ondenfed liquor
of the fecond experiment was about three. titedi as acidias thab
of the firft, as ie required 119°grainsyof ‘a diluted folution of falt
of tartar to faturate it, and theather only 39: ihe: ftandlardof
theburntiair was! 6; ay in theofecond: coe and: pi
the firtt. - OS -Sibg! “at embrerit. §
‘The intention of sft letting i in Korii dejpitopiitichted
ait ea the ‘two fat ie nepagaie ‘was, thatthe comdenfed! oo
er 10. 10%. 2 OVP oa goloce avad 1 woll was
er40 Mr. CAVENDIsH’s Experiments on Air.
-was expected to become more acid ag in as as: ibis wees]
‘to be the cafe.:
In the firft of thefe two experiments, an: ose! fe io air
to be exploded fhould be as: freeas poffible from common air,
the globe was firft filled with a mixture of dephlogifticated and.
43nflammable Jair, it was then exhaufted, and the air to be ex--
‘ploded let in3° by which meatis,.:though the globe was not per=
fetly.sexhaufted, very ‘little common air could be: left in it
In: the firft fet of experiments: this circumftance: was not
attended to, andthe purity of the eee ain was.
“peg to be examined in both fets. . : uO?
»iFrom what has been faid there: feems the vicnihl raiteaoe to
hire that dephlogifticated air is>only water deprived of its
phlogifton, and that inflammable air, as was before faid) is.
either phlogifticated water, orvelfe isi phingees but in i
probability the former. ft
oAs Mr. Watt, in a RE ‘eal bétomeyiife ese.
fuppofes water to confift-of dephlogifticated air and phlogifton
deprived of part of their latent heat, whereas. I take: no notice
of the latter circumftance, it may be proper to mention in a
few words the:reafon of this apparent difference betwen us. If
there be any fuch thing as elementary heat, it muft be allowed
that what Mr. Wart faysis true; but by the fame rule we
ought to fay, that the diluted mineral acids confift of the con=
centrated acids united to water and deprived of part of their
latent heat; that folutions of fal ammoniac, and moft other
other neutral falts, confift of the falt united to water and ele-
mentary heat; and a fimilar language ought to be ufed im
fpeaking of almoft all chemical combinations, as there are very
few: which are not attended with fome increafe or diminution
of heat, Now IJ have chofen to avoid this form of {peaking,
both
Mr. CAVENDISH’Ss Experiments on Air. IA}
both becaufe L:think it more likely that: there isino fueh thing
as elementary heat, and becaufe faying {fo in this inftance,
without ufing fimilar expreflions i in {peaking ‘of other chemical
unions, would be improper, and would lead to falfe ideas; and
it may even admit of doubt, whether the doing it in general
would not caufe more trouble and perplexity than it is worth.
‘There is the utmoift reafon to think, that dephlogifticated and
phlogifticated-air, as M. Lavoisier and ScHEELE fuppofe, are
quite diftin&. fubf{tances, and not differing only in their degrée,of
phlogiftication ; and that common air is a mixture of the two;
for if the dephlogifticated air is pretty pure, almoft the whole
of it lofes its elafticity: by: phi ogiftication, and, as appears: by
the foregoing experiments, is turned into water, inftead of
being converted into phlogifticated air.. In moft of the fore-
going experiments, at leaft +¢ths of the whole was turned into
water; and by treating fome dephlogifticated air with liver of —
fulphur, I have reduced it to lefs than 7,th of its original bulk,
and other perfons, I believe, have reduced it to a full lefs bulk;
fo that there feems the utmoft reafon to fuppofe, that the fmall
refiduum which remains after its phlogiftication proceeds only
from the impurities mixed with it. .
It was juft faid, that fome dephlogifticated air was tedpedl by
liver of fulphur to ,.th of its original bulk; the ftandard of
this air was 4,8, and confequently the ftandard of perfetly
pure dephlogifticated air fhould be very nearly 5, which is a
confirmation of the foregoing opinion; for if the ftandard of
pure dephlogifticated air is 5, common air muft, according to
this opinion, contain one-fifth of it, and therefore ought to lofe
one-fifth of its bulk by oo which is what itis,
oo? found to lofe.
Hiore
142 Mr, CavVennisi's 's Experiments on AUK.
From what has been faid, it follows, that inftead of fade
air is phlogifticated or dephlogifticated by any means, it would
be more ftriGly juft tocfay, iteis deprived of, on:receives, an
addition of dephlogifticated air; but as the other expreffion is
convenient, atid can fcarcely be confidered as improper, I thalf
full frequently make ufe of it in the remainder of this papers
There feemed great reafon to think, from Dr. PriesrhEy’s
experiments, that both the nitrous aid vitriolic acids were con=
vettible into dephlogifticated air, as that air is procured in the
greatelt quantity from fubftances containing thofe acids, efpe-
cially the forrier. .The foregoing experiments, however, feem
to fhew that no part of the acid is converted into dephlogitti-
cated ait, and that their ufe in prepdring it is owing only: fo
the great power which they poflefs of depriving bodies of
their phlogifton. A ftrong cotifirmation of this is, that red pres
cipitate, which is one of the fubftances yielding dephlogifti-
cated air in the greateft quantity; and which is prepared by
means of the nitrous acid, contains in reality noaeid, “Vhis)]
found by grinding 400 grains of it with fpirits of fal ammo-
niac, and keeping thern together for fome days in a bottles
taking eare to fhake them frequently. The red colour of the
precipitate was rendered pale, but not entirely deftroyed; being
then wafhed with water and filtered, the clear, liquor asked
On evaporation not the leaft ammoniacal falt. |; : .
It is natutal to think, that if any nitrous acid had been con=
tained in the red precipitate, it would have united to the volas
tile alkali arid have formed ammoniacal nitre, and would, have
been perceived on evaporation ; but in order to, determine more
eertainly whether this would be the cafe, I dried; fome of the
fame folution of quickfilvet from which the red precipitate was
prepared with a lefs heat, fo that it acquired only an orange
colour,
Mr. Cavenpisn’s- Experiments on Air. 143
colour, and treated the. fame quantity of it with volatile alkali
in the fame manuer as before. It immediately caufed an effer-
veicence, changed the colour to grey, and yielded 52 grains
of ammoniacal nitre. There is the utmoft reafon to think,
therefore, that- red precipitate contains no nitrous acid; and
coniequently that, in procuring dephlogifticated air fromit, no
acid is converted into air; and it is reafonable to Geen.
therefore, that no. fuch change is produced in procuring it from
any other fubftance.
Tt remains to. confider in what manner thefe acids a& in
producing dephlogifticated air. The way in which the nitrous
acid acts; in the production of it from red precipitate, feems to
be as follows. On: difti illing the mixture of quickfilver and
{pirit of nitre, the acid comes over, loaded with phlogitton, im
the form of nitrous vapour, and continues to do fo till the re-
maining matter acquires its full red colour, by which time all
the nitrous acid is driven over, but fome of the watery part full
remains behind, and adheres ftrongly to the quickfilver; fo that
the red precipitate may be confidered, either as quickfilver de-
prived. of part of its phlogifton, and united to a certain portion
of water, or as quickfilver united to dephlogifticated air™; after
which, on further increafing the heat, the water in it rifés
deprived of its phlogifton, that is, in the form of dephlogifticated
* Unlefs we were much better acquainted than we are with the manner in
which different fubftances are united together in compound bodies, it would be ~
ridiculous to fay, that it is the quickfilyer in the red precipitate ace deprived
of its phlogifton, and not the water, or that it is the water and not the quighlaetce
all that we can fay is, that red precipitate confifts of quickfilver and water, one
or both of which are deprived of part of their phlogifton.. In like manner, during
the preparation of the red precipitate, it is certain that the acid abforbs phlo-
gifton, either from the quickfilyer or the water; bus we are by no means authorifed
to fay from which. j
alr,
’
i ed Mr. CAvEND! 1s S Experiments on ‘ai mre
Ait, “and at the famé’ ‘time ‘the quick filver diftils | over in its ‘alee
tallic form. It is juftly temarked by Dr. Prrsriey, that the’
{olution of quickfilver dves -not begin to yield aes 3%
air till it acquires its red colour.
~ Mercurius calcinatts appears to bé only quickfilver’ which
has abforbed dephlogifticated air from the atmofphere during
its preparation; accordingly, by giving it a fufficient heat, the
dephlogifticated air is driven off, arid the quickfilver: acquires
its original form. It feems therefore that mercurius calcinatus
and red precipitate, though prepared in a différent manner, are
very nearly the fame thing. |
From what has been faid it follows, a red precipitate bar
mercurius calcinatus contain as much phlogifton as the quick-
filver they are prepated from but yet, as uniting dephlogifti-
cated air to 4 metal comes to the fame thing as depriving it of
part of its phlogifton and adding water to it, the quickfilver
may ftill be confidered as deprived of its phlogifton; but the
imperfect metals feem not only to abforb dephlogifticated air
during their calcination, ‘but alfo to be really deprived of part
of their phlogifton, as they do not acquire their metallic form
by driving off the dephlogifticated air.
In procuring dephlogifticated ait from nitre, the acid acts in
a different manner, as, upon heating the nitre red-hot, the de«
phlogifticated air rifes mixed with a little nitrous acid, and at the
fame time the acid remaining in the nitre becomes very much
phlogifticated ; which fhews that the acid abforbs phlogifton
from the water in the nitre, and becomes phlogifticated, while
the water is thereby turned into dephlogifticated air. On dif-
tilling. 3155 grains of nitre in, an unglazed earthen retort, at
yielded 256000 grain meafures of dephlogifticated air*, the
ftandard
* This is, about eighty-one grain meafures from one grain of nitre; and the
weight
Mr. Cavenpisn’s Experiments on Air. 145
ftandard of different parts of which varied from 3 to 46 5, but
at a medium was 3,35. The matter remaining in the retort
diffolved readily i in water, and tafted alcaline and cauftic. On
adding diluted {pirit of nitre to the folution, {trong red fumes
were produced; a fign that the acid in it was very much phlo-
gifticated, as no fumes whatever would have been produced on
adding the fame acid to a folution of common nitre; that part
of the folution alfo which was fuperfaturated with acid became
blue; a colour which the diluted nitrous acid is known to af=’
fame when much phlogifticated. The folution, when fatu-
rated with this acid, loft its alcaline and cautftic tafte, but yet
tafted very different from true nitre, feeming as if it had been
mixed with fea-falt, and alfo required much lefs water to dif-
folve it; but on expofing it for fome days to the air, and add-
ing frefh acid as faft as by the flying off of the fumes the al-
cali predominated, it became true nitre, unmixed, as far as I
could perceive, with any other {alt *.
It has been remarked, that the dephiogifticated air procured
from nitre is lefs pure, than that from red precipitate and many
other fubftances, which may perhaps proceed from unglazed
earthen retorts having been commonly ufed for this purpofe,
and which, conformably to Dr. PrrestLey’s difcovery, may pof-
fibly abforb fome common air from without, and emit it along
with the dephlogifticated air; but if it fhould be found that the
dephlogifticated air procured from nitre in glafs or glazed )
earthen veffels is alfo impure, it would feem to fhew that part
weight of the dephlogifticated air, fuppofing it 800 times lighter than water, is one
tenth of that of the nitre, In all probability it would have yielded a much greater
quantity of air, if a greater heat had been applied.
* This phlogittication of the acid in nitre by heat has been obferved by Mr.
SceweEe ; fee his experiments on air and fire, p. 45, Englifh tranflation.
Vor. LXXIV, U of
146. Mr. Cavenpisu’s Experiments on Air,
of the acid in the nitre 1s turned into, phlogifticated air, by ab ;
forbing phlogifton from.the watery part. .
From what has been faid it appears, that there is a . confider=
able difference i in the manner m which the acid acts in the pro-=
duGtion, of dephlogifticated air from red precipitate and from
nitre; in the former cafe the acid comes over firft, leaving the
remaining fubftance deprived of part of its phlogifton ; 1n the.
latter the dephlogifticated air comes firft, leaving the acid loaded ,
with the phlogifton of the water from which it was formed.
On diftiling a mixture of quickfilver and oil of vitriol to
drynels, part of the acid.comes over, loaded with phlogifton, .
in the form of volatile fulphureous acid and vitriolic acid air; fo
that the remaining white mafs may be confidered as confifting
of quickfilver deprived of its phlogifton, and united to a certain |
proportion of acid and water, or of plain quickfilver united to
a certain proportion of acid and dephlogifticated air. Accord-
ingly on urging this white mafs with a more violent heat, the .
dephlogifticated air comes over, and at the fame time part of
the quickfilver rifes in its metallic form, and alfo part of the
white mafs, united in all probability to a greater proportion of
acid than before, fublimes; fo that the rationale of the pro=
duction of dephlogifticated air from turbith mineral, and from, .
red precipitate, are nearly fimilar,
True turbith mineral confifts of the abovementioned white -
mafs, well, wafhed with water, by which means it acquires a
yellow colour, and contains much lefs acid than the unwafhed
mafs. Accordingly it feems likely, that on expofing this, to
heat, lefs of it fhould fublime without being decom pounded, and ~
confequently that more dephlogifticated air fhould be. procured
from it: than from the unwathed mafs,
This.
Mr. Cavennisy’s Experiments on Air. 147
This is an inftance, that the fuperabundant vitriolic acid may,
in fome cafes, be better extracted from the bafe it is united to
by water than by heat. Vitriolated tartar is another inftance;
for, if vitriolated tartar be mixed with oil of vitriol and expofed
even to a pretty ftrong red heat, the mafs will be very acid;
but, if this mafs is diflolved in water, aud evaporated, the crv
fials will be not fenfibly fo.
In all probability, the vitriolic acid a&ts in the fame manner in
the produGtion of dephlogifticated air from alum, as the nitrous
does in its produétion from nitre ; that is, the watery part comés
aver firft in the form of dephlogifticated air, leaving the acid
charged with its phlogifton. Whether this is alfo the cafe
with regard to green and blue vitriol, or whether in them the
acid does not rather act in the fame manner as in turbith mine-
ral, I cannot pretend to fay, but I think the latter more
likely. |
There is another way by which dephlogifticated air has been
found to be produced in great quantities, namely, the growth
of vegetables expofed to the fun or day-light; the rationale of
which, in all probability, is, that plants, when affifted by the
light, deprive part of the water fucked up by their roots of its
phlogifton, and turn it into dephlogifticated air, while the
phlogifton unites to, and forms part of, the fubftance of the
Pern. it 100
There are many circumftances which fhew, that light has a
remarkable power in enabling one body to abforb phlogifton
from another. Mr. Senezier has obferved, that the green
tinéture procured from the leaves of vegetables by {pirit of wine,
quickly lofes its colour when expofed to the fun in a bottle’ not
more than one third part full, but does not do fo in the dark.
or if the bottle is quite full of the tin@ture, or if the air in it
’ U2 1S
cd
148 Mr. Cavenpisn’s Experiments on Air.
is phlogifticated ; whence it is natural to conclude, that the
light enables the dephlogifticated part of the air to abforb
phlogifton from the tincture ; and this appears to be really the
cafe, as 1 find that the air in the bottle 1s confiderably phlogif-
ticated thereby. Dephlogifticated {pirit of nitre alfo acquires a
yellow colour, and becomes phlogifticated, by expofure to the
fun’s rays *; and 1 find on trial that the air in the bottle in
which it is contained becomes dephlogifticated, or, in other
words, receives an increafe of dephlogifticated air, which fhews
that the change in the acid is not owing to the fun’s rays com-
municating phlogifton to it, but to their enabling it to abforb
phlogifton from the water contained in it, and thereby to pro-=
duce dephlogifticated air. Mr. ScHEELE alfo found, that the
dark colour acquired by luna cornea on expofure to the light,
is owing to part of the filver being revived; and that gold, dif>
folved in aqua regia and deprived by diftillation of the nitrous
and fuperfluous marine acid, is revived by the fame means;
and there is the utmoft reafon to think, that, in both cafes, the
revival of the metal is owing to its abforbing phlogifton from
the water.
Vegetables feem to confift almoft intirely of fixed and phlo-
gifticated air, united toa large proportion of phlogifton and fome
water, fince by burning in the open air, in which their phlogifton
unites to the dephlogifticated part of the atmofphere and forms
* If fpirit of nitre is diftilled with a very gentle heat, the part which comes
over is high coloured and fuming, and that which remains behind is quite colour
lefs, and fumes much lefs than other nitrous acid of the fame ftrength, and the
fumes are colourlefs. This is called dephlogifticated fpirit of nitre, as it appears
to be really deprived of phlogifton by the procefs, The manner of preparing it,
as well as its property of regaining its yellow colour by expofure to the light, is
mocntioned by Mr. ScHEELE in the Stockholm Memoirs, 1774.
water,
Mr. Cavennisu’s Experiments on Air. r49
water, they feem to be reduced almoft intirely to water. and
thofe two kinds of air. Now plants growing in water without
earth, can receive nourifhment’ only from the water and air,
and muft therefore in all probability abforb their phlogifton
from the water. It is known alfo that plants growing in the
dark do not thrive well, and grow in a very different manner
from what they do when expofed to the light.
From what has been faid, it feems likely that the ufe of rite
in promoting the growth of plants and the produdtion of
dephlogifticated air from them, is, that it enables them to
abforb phlogifton from the water. To this it may perhaps be
objected, that though plants do not thrive well in the dark, yet
‘they do grow, and fhould therefore, according to this hypo-
thefis, abforb water from the atmofphere, and yield dephlo-
gifticated air, which they have not been found to do. But we
have no proof that they grew at all in any of thofe cafes in
which they were found not to yield dephlogifticated air; for
though they will grow in the dark, yet their vegetative pow-
ers may perhaps at firft be intirely checked by it, efpecially
confidering the unnatural fituation in which they muft be
placed in fuch experiments. Perhaps too plants growing in
the dark may be able to abforb phlogifton from water not
much impregnated with dephlogifticated air, but not from
water ftrongly impregnated with it; and confequently, when
kept under water in the dark, may perhaps at firft yield fome
dephlogifticated air, which, inftead of rifing to the furface,
may be abforbed by the water, and, before the water is fo
much impregnated as to fuffer any to efcape, the plant may
ceafe to vegetate, unlefs the water is changed. Unlefs there-
fore it could be fhewn that plants growing in the dark, in
water alone, will increafe in fize, without yielding dephlo-
gifticated
150 _ Mr. Cavenpisn's Experiments on Aur.
gifticated air, and without the water becoming more impregnated
with it than before, no objection can be drawn from thence. °
Mr. Senesier finds, that plants yield much more dephlogifti- °
cated air- in diftilled water impregnated with fixed air, than in
plain diftdled water, which 1s‘ perfectly conformable to the
abovementioned hypothefis ; for as fixed air is a principal con-
flituent part of vegetable fubftances, itis reafonable to fuppofe
that the work of vegetation will go on better in water con-
taining this fubfance, than in other water.
There are feveral memoirs of Mr. Lavotster publithed by
the Academy of Sciences, in which he intirely difcards phlo-«
gifton, and explains thofe phenomena which have been ufually
attributed to the lofs or attraction of that fubftance, by the ab-
forption or expulfion of dephlogifticated air; and as not only
the foregoing experiments, but moft other phenomena of na-
ture, feem explicable as well, or nearly as well, upon this as
upon the commonly believed: principle of phlogifton, it may
be proper briefly to mention in what manner I would explain
them on this principle, and why I have adhered to the other.
In doing this, I fhall not conform ftri@tly to his theory, but
fhall make fuch additions and alterations as feem to fuit it beft
to the phenomena; the more fo, as the foregoing experiments
may, perhaps, induce tne author himfelf to think fome fuch
-additions proper. ,
According to this hypothefis, we muft fuppofe, that water
confifts of inflammable air united to dephlogifticated air; that
nitrous air, vitriolic acid air, and the phofphoric acid, are alfo
combinations of phlogifticated air, fulphur, and phofphorus,
with dephlogifticated air; and that the two former, by a fur-
ther addition of the fame fubftance, are reduced to the common
nitrous
, Mr, Cavenpisn’s' Experiments on Air, ror
nitrous.and vitriolic acids; that the metallic calces conSft of
the metals themfelves united to the fame fubftance, commonly,
however, with a mixture of fixed airs that’ on expofing the
calces of the perfect metals to a iufficient heat, all the déphlo-
gifticated air is driven off, and the calces are reftored to their
metallic form; but as the calces of the imperfe metals are
vitrified by heat, inftead ef recovering the metallic form, it:
fhould feem as if all the dephlogifticated air could not be driven
of from them by heat alone. In hike manner, according to
this hypothefis, the rationale of the produ&tion of dephlogifti- »
cated air from red precipitate is, that during the folution of
the quickfilver in the acid and the fubfequent calcination, the
acid is decompounded, and quits part of its dephlogifticated air
tothe quickfilver, whereby it comes over in the form of nitrous
air, and leaves the quickfilver behind united to dephlogiftica-
ted air, which, by a further increafe of heat, is driven off,
while the quickfilver re-aflumes its metallic form. In pro-
curing dephlogifticated air from nitre, the acid 18 alfo decom-
pounded ; but with this difference, that it fuffers fome of its de-
phlogifticated air to efcape, while it remains united to the alkali
itfelf, in the form of phlogifticated nitrous acid. As to the
production of dephlogifticated air from plants, it may be faid, .
that vegetable fubftances confift chiefly of various combina- -
tions of three different bafes, one of which, when united to
dephlogifticated air, forms water, another fixed air, and the
third phlogifticated air; and that by means of vegetation each
of thefe fubftances are decompofed, and yield their dephlogifti-
cated air; and that in burning they again acquire dephlogifti-
cated air, and are reflored to their priftine form.
‘It feems, therefore, from what has been faid, .as if the phe-—
nomena of nature might be explained very well on this princi-
5 ciple,
152" Mr. CAvenpIsH’s Experiments on Air.
“ciple, without! the help of phlogifton ; and indeed, as adding
dephlogifticated air to a body‘comes’to the fame thing as de-'
priving it of its phlogifton and adding water to it, and as there
are, perhaps, no bodies entirely deftitute of water, and as I
know no way by which phlogilton can be transferred from one
body to another, ‘without leaving it uncertain whether water -
is not at the famé time transferred, it will be very difficult to
determine by experiment which of thefe opinions is the trueft
but as the commonly received principle of phlogifton explains
all phenomena, at leaft as well as Mr. Lavorster’s, I have
adhered to that. There is one circumftance alfo, which though °
it may appear to many not to have much force, I own has fome:
weight with me; it is, that as plants feem to draw their nou-
rifhment almoft intirely from water and fixed and phlogifticated
air, and are reftored back to thofe fubftances by burning, it
feems reafonable to conclude, that notwithftanding their infi-
nite variety they confift almoft intirely of various combinations
of water and fixed and phlogifticated air, united according to one
of thefe opinions to phlogifton, and deprived according to the
other of dephlogifticated air; fo that, according to. the latter
opinion, the fubftance of a plant is lefs compounded than a -
mixture of thofe bodies into which it is refolved by burning; _
and it is more reafonable to look for great variety in the more
compound than in the more fimple fubftance.
Another thing which Mr. Lavoisier endeavours to prove is,
that dephlogifticated air is the acidifying principle. From what
has been explained it appears, that thisis no more than faying,
that acids lofe their acidity by uniting to phlogifton, which with °
regard to the nitrous, vitriolic, phofphoric, and arfenical acids
is certainly true.. The fame thing, I believe, may be faid of
the acid of fugar; and Mr. Lavoisier’s experiment is a
{trong
Mr. CAVENDISH’s Expertments on Air. 153
{trong confirmation of BerGMAN’s opinion, that none of the
{pirit of nitre enters into the compofition of the acid, but that
it only ferves to deprive the fugar of part of its phlogifton.
But as to the marine acid and acid of tartar, it does not appear
that they are capable of lofing their acidity by any union with
phlogifton. It is to be remarked alfo, that the acids of fugar
and tartar, and in all probability almoft all the vegetable and
animal acids, are by burning reduced to fixed and phlogifticated
air, and water, and therefore. contain more phlogifton, or lefs
dephlogifticated air, than thofe three fubftances.
Vo. Tree. r x
: f' 15% ; ‘a | a spies Bad
XIV. Remarks ob Mr. Cavendith’s Experiments on Aire In @
Letter from Richard Kirwan, By. F R.S. to Sir Jofoph
| Banks, Bart. P. RLS.
Read Feb. 5, 17845
STR,
AVING liftened with much attention, and derived
much ufeful information from the very curious experi-
ments of Mr. CavENpIsH, read at our laft meeting, it is with
peculiar regret I feel myfelf withheld from yielding an intire
affent to all he has advanced in his very ingenious paper; and
it is with ftill greater that I find myfelf obliged, by reafon of
the oppofition of fome of his deductions to thofe I had the ho-
nour to lay before the fociety about two years ago, to expofe
the reafons of my diffent, through your mediation, before this
meeting. |
In the paper already mentioned, read in April, 1782, I at-
tributed the diminution of refpirable air, obferved in common —
phlogiftic procefles, to the generation and abforptien of fixed
air, which is now known to be an acid, and capable of being
abforbed by feveral fubftances. ‘That fixed air was fome how
or other produced in phlogiftic procefles, either by /eparation
or compofition, I took for granted from the numerous experi-
ments of Dr. PriestLey ; and among thefe I feleéted, as leaft
liable to objection, the Calcination of Metals, the decompofi-
,) : tion
Mr, Kinwan’s Remarks, &e. 450
tion of nitrous by mixture with refpirable air, the, phiogiftica-
tion of refpirable air by the electric fpark, and, laftly, that ef-
fected by amalgamation. In each of thefe inftances Mr, Caven-
DIsH is of opinion, that the diminution of refpirable air is
owing to the production ef water, which, according to him, is
formed by the union of the phlogifton, difengaged in thofe pro-
cefles, with the dephlogitticated part of common air; and that
fixed air is never produced in phlogiftic procefies, except fome
animal or vegetable {ubftance is concerned in the operation,
from whofe decompofition it may arife. ‘To which of thefe
caufes the diminution of refpirable air is to be attributed, I thall
now endeavour to elucidate.
Of the Calcination of Metals.
I attributed the diminution of air by the calcination of
metals, to the converfion of the dephlogifticated part of com-
mon air into fixed air, by reafon of its union with the phlo-
gifton of the metal, for this plain reafon, becaufe I find it ac-
knowledged on all hands, that the calces of all the bafe metals
yield fixed air, when fufficiently heated. Mr. Cavendith allows
the fact in general, but afcribes the fixed air found in them to
their long expofure to the atmofphere, in which he fays fixed
air pre-exifts ; but that it exifts in common air in any quantity
worth attending to, or is extracted from it in any degree, I
take the liberty of denying, grounded on the following facts.
Firft, I have frequently agitated 18 cubic inches of common air
in 2 of lime-water, and 2 of common air in 18 of lime-water,
but could never perceive the flighteft milkinefs; and yet the
thoufandth part of a cubic inch of fixed air would thus be made
fenfible ; for if a cubic inch of it be diffolved in 3 ounces of
. xX 2 water,
15.6 Mr. Kinwan’s Remarks on
water, a few drops of that water let into lime-water will pro-
duce acloud. Mr. Fonrana fays, he frequently agitated 1 cubie
inch of Tinéture of Turnfole in 7 ot 800 of common air, with-
out reddening it (23 Roz. p. 188.); and yet, according to Mr.
Bzercoman, 1 cubic inch of fixed air is fufficient to redden 50
of Tincture of Turnfole (1Berem. 11.); from whence lam apt
to think, that 700 cubic inches of common air do not even
contain 2th of a cubic inch of fixed air. Dr. Wuyrr found
that 12 ounces of {trong lime-water, being expofed to the open
air for rg days, ftill retammed about 1 grain of lime, (on Lime-
water, p. 32.). Now 12 ounces of {trong lime-water contain
at moft 9,5 grains of lime, and 1 grain of lime requires only
0,56 of a cabic inch of fixed air to precipitate it, the thermo-
meter at 55 and the barometer at 29,5, as I have found. There=
fore in 1g. days this lime-water did not come in contact with
more than four cubic inches of fixed air; yet it is certain that
a large quantity of fixed air is continually difengaged, and
thrown into the atmofphere, by various proceflés, as putre-
faction, combuftion, &c. but it feems equally certain that it is
either decompofed, or more probably abforbed by various bodies.
Mr. Fontana let loofe 20000 cubic inches of fixed air, in a
room whofe windows and doors were clofed, yet in half an
hour after he could not difcover the leaft trace of it (ibid.).
Though fixed air perpetually oozes from the floor of the Grotto
del Cane, yet at the diftance of four or five feet from the ground
none is found; animals may live, lights burn, &c. (Roz. Ibid. Mem.
Stockh. 1775.). If diftilled water be expofed to the atmofphere,
it.is never found to abforb fixed air, but rather dephlogifticated
air, according to Mr. ScHEELE’s experiments, which could never
happen if the atmofphere contained any fenfible proportion of
hs iu 7 Pies | tieate ior fixed
Mr. Cavennisy’s Experiments on Air. ise
fixed air; nor has rain-water been ever found to contain any,
which it certainly fhould on the fame hypothefs; even Mr.
CavenpisH himfelf could find no fixed air in the refiduum or
produéts of about 1040 ounce meafures of common air, which
he burnt with inflammable air.
It is true, Dr. PrizstLey fuppofed common air to. cone
tain 2. of its bulk of fixed air; but he drew this conclufion
not from any direct experiment, but from the quantity of fixed
air produced by breathing, which he at that time believed to
have been barely precipitated, and not generated, an opinion
which he has found reafon to alter from his own experiments.
I think I may therefore conclude, that the quantity of fixed
air contained in the atmofphere is abfolutely inappreciable.
Secondly, fuppofing the atmofphere to contain a very fmalk
proportion of fixed air, yet Ido not think it can be inferred
that metals, during their calcination, extract any, becaufe I
find that lime expofed to red heat ever fo long extras none,
though it is formed by a calcination in open air, which lafts
at leaft as long as that of any metal; neither does precipitate
per fe attra&t any, though its calcination lafts feveral months ;
“nor does this proceed from the want of affinity, for if a fatu-
rate folution of mercury in any of the acids be precipitated by
a mild vegetable alkali, very little effervefcence is perceived,
and the precipitate weighs much more than the, quantity of
mercury employed, and that this increafe, of weight arifes in
part from the fixed air abforbed will prefently be feen.
Since then metals may be calcined in clofe veflels, fince they.
then abforb one fourth part of the common air to which they —
are expofed, fince all metallic calces (except thofe of! mercury,
which I fhall prefently mention) yield fixed air, fince common
| alr
co Mr. Kirwan’s Remarks on
air contains fearce any fixed air; is it not apparent that’ the
fixed air thus found was generated by the very a& of calcination,
by the union of the phlogilton of the metal with the dephlo-
gifticated part of the common air, fince after the operation the
metal is deprived of its phlogifton, and the air of its ee
gifticated part ?
But Mr. Cavenpisy objects, that no one has extracted sista
air from metals calcined in clofe veflels. To which I anfwer,;
that this further proof is difficult, and no way neceflary ; itis —
difficult, becaufe the operation can eafily be performed only on
{mall quantities ; it is unneceflary, becaufe it differs from the
operation in open air only by the quantities of the materials
employed, in every other refpect it 1s exactly the fame. Since
Mr. CavenpisH fufpects the refults are different, it is incum-
bent on him to thew that difference; but until then, accord-—
ing to Sir Isaae Newton’s fecond rule, to natural effects of
the fame kind the fame caufes are to be afigned, as far as it may
be done, that is, until experience points out fome other caufe,
Tt may further be urged, that precipitate per fe yields only
dephlogifticated air, that minium alfo yields a large proportion
of it. This difficulty I have formerly anfwered by afferting, »
that thefe calces are in fact united only to fixed air, and that
they yield dephlogifticated air, merely becaufe the fixed air is
decompofed by the total or partial revivification of the metallic
fubftances; this 1 think may be demonftrated by the following
experiments. Let fublimate corrofive fingly be treated in any —
manner, it will not yield dephlogifticated air (4 Pr. 240.) 3 but
Jet a folution of fublimate corrofive be precipitated by a mild
fixed alkali, this precipitate wafhed, dried, and diftilled in a
pneumatic apparatus, will yield dephlogifticated air, and the
mers
Mr. Cavennisn’s Experiments on A,r. 15g
mercury will be revived; but, if the foilution of fublimate cor-
rofive be precipitated by lime-water, it feems no air will be pro-
duced. Here then we fee, rft, that the calx of mercury unites
with fixed air; and, 2dly, that this fixed air is, during the
revivification of the mercury, converted into dephlogitticated
air. Again; let one ounce of red precipitate, which, according
to Mr. CAVENDISH, contains no nitrous acid, be diftilled with
two ounces of filings of iron; this quantity of precipitate,
which, if diftilled by itfelf, would yield 60 ounce meafures of
dephlogifticated air, will, when diftilled with this proportion
of filings of iron, yield 40 ounce meafures of fixed air, as Dr.
Prrestiey has fhewn in his laft paper: whichever way this
_is explained, fome or other of my opinions are confirmed; for
either the mercurial calx is already combined with fixed air
(which I believe to be the cafe), and this air paffes undecom-
pofed, becaufe the mercury extracts phlogiften from the iron 3
or it contains dephlogifticated air, which is converted into fixed
_ air by its union with the phlogifton of the iron.
If precipitate per fe be digefted in marine acid, the mercury
will be revived (3 Bere. 415.). Now this calx does not de-
» phlogifticate the marine acid; for this acid, when dephlogitti-
cated, diflolves mercury; how then does it revive it, if not by
expelling the fixed air contained in it, which in the moment of
its expulfion is decompofed, leaving its pilogEron to the mercu-
zy, which is thereby revived?
Again: if litharge be heated in a gun-barrel, it will afford more
fixed and lefs dephlogifticated air than if heated in glafs or
earthen veffels. Does not this happen, becaufe the calx of
lead, receiving fome phlogifton from the metal, does not de-
_ phiogifticate fo great a proportion of the fixed air as it other-
wife would?
Fur- —
160 Mr. Kirwan’s Remarks on
_ Farther : ‘there is no fubftance which yields dephlogifticated”
, but yields alfo fixed air, even precipitate per /é not except-"
ah (3 Priest. £6.) and what is remarkable, they all yield fixed”
air firft, and dephlogifticated air only towards the end of the —
procefs. Does not this happen becaufe metallic calces attra& phlo-"
gifton fo much more ftrongly, as they are more heated? ‘Thus
raany calciformy iron ores become magnetic by calcination, though’
they were not fo before; fo alfo do all the calces of iron when ex-’
pofed to the focus ofa burning elafs (5 Did. Chy. 179). Thus®
vaercury cannot be calcined’ but in a heat inferior to that in which:
it boils; thus minium cannot be formed but in a moderate heat,’
and if heated {till more it returns to the ftate of mafficot, 1 in.
which it was before it became minium, and much -of it js re=- .
duced. So if a folution of luna cornea in volatile alkali be tri+
turated with mercury, the filver will be revived, and the ma-
rine acid unite to the mercury, which fhews this acid has a
ftronget attraction to Mercury than to filver; yet if fublimate’
corrofive and filver be diftilled in a {trong heat, the mercury’
will be revived, and the marine acid unite to the filver, which
fhews that the attraction of mercury to phlogifton increafes'
with the heat applied. ;
Before I conclude this head, I will mention another experi~'
ment, which I think decifive in favour-of my opinion of the’
compofition of fixed air. If filings of zinc be’ digefted in ‘a’
cauftic fixed alkali in a gentle heat, the zinc will be diflolved:
with effervefcence, and the alkali will be rendered in great
meafure mild. Butif, miftead of filings of zinc, flowers of zine
be ufed, and treated in the fame manner, there will be no
folution, and the alkali will remain cauftic. In the firft cafe
the effervefcence arifes from the production of inflammable air,
which’
Mr. Cavennisn’s, Experiments on Air, 164
which. phlogifticates the common, air contiguous to ghee a pro-
duces. fixed - air, »which is immediately abforbed. by the alkali,
and renders it mild... In the fecond ¢afe, ‘no. inflammable alr is
produced, the common air is not, phlogifticated; and confe-
quently the, alkali; remains. cauftic*. This experiment alfo
proves that metallic calces attract fixed air more ftrongly than
alkalies attract it; for the ¢alces of zinc are known to contain
fixed air, and yet alkalies digefted with them remain cauttic ; 3
and this-accounts for. the flight turbidity of lime-water when
metals are calcined over it; for as foon as the phlogifton i is
difengaged from the metal, and before it has abforbed the
whole quantity of fire requilite to throw it into the form of in-
flammable air, it meets with the dephlogifticated part of. the
common air on the furface of the metal, and there, forms fixed
air, which 1s inftantly abforbed by the calx with which it is in
eonta&, fo that itis not to be wondered that it does not unite
to the lime fron which it is diftant. .
er the Decompofi ition of Nitrous Air sy mixture UNE
Commoz Air.
AS foon as Thad heard Mr. Cavenptsn’s paper shade D ”
‘about trying whether lime would be precipitated from lime-
water during the procefs, an expetiment I had never made
before with common air, taking it for granted that it was fo,
from the repeated experiments of Dr. Prrestiey, and indeed
of = niet wes had ticated ie aheeee ‘and, in —_
* See Mr. ieeclene? seg, soni on zinc. Mem. Par: Ap77s po 7&8.
+ See a Pr. Ll 4s Ha 2 2Pr, 218. Font. Recherches Phe P7701 Chy.
Dij. 3240 7 sci ' ‘i
_ Vor. LXXIV, ee ee ee REE
162 - on Mr. Kirwan’s Remarks on. Mi
when 1 made the experiment’ with nitrous air prepared and
confined by the water of my tub, I found lime-water admitted
to it inftantly precipitated. “But after I-had read Mr. Caven=
DisH’s paper, which he had the politenefs to permit, me, and
had, according to his direGtion, received the nitrous air over.
lime-water, I did not then perceive the leaft milkinefs after ad-
mitting common air. After 12 hours ¥ indeed. perceived a
whitith’duft, on the bottom of the glafs veflél im which I made
the experiment, which I cannot aflure to be ‘calcareous; and,
on breathing into the lime-water, an evident milkinefs enftied;
fo that I little doubt but the precipitation I obferved in the firft
experiment arofe from the decompofition of the aerial felenite
contained in the water of the tub. And itis very poflible that
the precipitation of lime, which I perceived fome years agoon
mixing dephlogifticated air and nitrous air, might have arifen
from the fame caufe, or from fixed ‘air pre-contained in the de-
phlogifticated, as this laft had not been wathed in lime-water.
YetI do not think the failure of this experiment at all conclufive
againft the fuppofed production of fixed air on this occafion,
becaufe the quantity of fixed air is fo fmall, that it may well be
fuppofed to unite to the nitrous felenite formed in the lime-
water. It is well known that a fmall quantity of fixed -air is
capable of uniting to all neutral falts: thus Dr. PrizsTLEy has
extracted it from) tartar vitrialate and alum, (2 PR. 1 Fis I 16.)
and gypfum, (2 Pr. 80.); and Dr. Mac Brive found it in, nitre
and common falt, though in {mall quantity. But to try whether
nitrous felenite would attract any, I made a folution of chalkin
nitrous acid, which, when faturate, weighed 381,25 grains ; but,
being expofed to 'the air fora few hours, it weighed 382,25. I
afterwards took avery dilute nitrous acid, in whichan acid tafte
was barely perceptible, and impregnated it with a very {niall pro-
ME 7 portion
Mr. Cavennisu's Exseriments -on Air. 1,63,
poftion’ of fixed air, and then let fall a few drops of it into lime:,
water} -not the fmalleft cloud was -perceived, and yet.when. L,
breathed into it afterwards, it-became milky ina few feconds ;:
fo: that: ‘this-experiment 1 is, perfedtly: aialogonate to that in which.
nitrous-and common air were mixed. ni gece ad
» But if nitrous air and common air be mixed over (6 ie Mere,
cury, the refult is intirely adverfe to the opinion of MroCa-.
VENDIsH; and favourable to mine; for. in this cafe the com-.
mon air is not at all diminifhed until water is admitted to it, and)
the mixture agitated a few minutes,- and then the dimiaution. 1 1s.
nearly ‘the fame as if the mixture were made over, water... Thus
when I mixed two cubic inches, of common air with one.of,
nitrous air, they. occupied the. {pace of two inches and .one-
eighth; and the -furface of the mercury was immediately .cal- .
cinéed ; which fhews that the inch of nitrous air was decom-.
pofed, and produced‘ nitrous acid ; but the common ait. was. un-.
diminifhed ; and the,one eighth of an inch over and above. the.
two inches,of common air, proceeded from an. addition of, new,
nitrous air, formed by. the corrofion of the furface of the mer-..
cury... That the common air, fhould remain, undiminithed. is.,
eafily explained in my fyftem, becaufe fixed, alr AS), formed,,
which, on this occafion, muft remain eutitecbed. at leaft for
a long time, as there is nothing; at hand that can immediately
receive it 3 and hence, if water be admitted foon after the mix-
turé of both airs} the diminution will be nearly: the fame as?if
the siixture’ had! been originally! made over water, ‘though ict“
exactly the fame ;“becaufe the: nitrous air, produced by the?
union of the newly formed: nitrous-acid with’ the mercury,: is¢
not entirely -abforbable by water-But, in.Mr. Cavenpdisn’s®
hypothefis, the'common air fhoald be diminifhed juft as-much:
asif the mixture were: made over water ; for, accdrding to. him, {.
ons Nie this
tOe \ Mr. ewe 5 fieonieae D:
this detenndda arifés from ‘the’ converfion of vit — |
catéd! part ‘Of the « common \ait into water, ‘which water frould
immédiately unité’ to the ‘nitrous falt of mercury, and leave’
the common aif leflened in its bulk by a portion comménfurate’ ;
to that converted into water, or, if he will not ‘allow the water:
to have immediately united to the mercurial faleyiat Teaft'by
the difference of the bulk of the water produced, ‘and that of an’
equal'weight of the common air Converted into ‘it > but! neither’
happens; for the common ' dit ‘is noe ‘at'‘all’ diniinifhed’s not!
can he ‘explain, confiftently with’ his’ fyftem, ‘why the adm:
fion of water fhould immediately’ produce ’ ‘a diminution ‘in! thet
common air, 45,‘ ‘according’ ‘to him, it conftaitis - ‘nothing ‘that’
can'be abforbed:'’ Dr. Prizstiey has remarked, that if a mix:
tureof both airs be fuffeted to ftand feveral hours, even the ads
miffioh of water will produce no diminution. This is owing”
to two caufes's 1ft, becaufe a large quantity of nitrous air is’
produced, by the continued ation of the ‘contentrated ‘nittoug’
acid newly formed; and, ‘2dly, bécaufe'the fixed-airj on?
whofe abforption’ the diminution ‘depends, is’ abforbed bythe:
mercurial falt, as” may: be’ ‘inferred from” se experiment’ int
1 Lavorsier,. P. 248. OE gl t yan ‘ors beri geyniss
x b204 FIT 8 pHa) Just ‘ ; cy ett. 7 (OP oh
Of the Dininution of Comnion — by the Eleétri¢ Spark.
Of all the is Giuiens of the wcaisa produiet: of fixed, aity
by, the umon of :phlogifton' withthe dephlogifticated part. off;
common air, there is none perhaps fo convineing, \as, thatljexr.
hibited by: taking the elé€tric. fpark. through common, air, over,
a. folution of litmhs, or lime-water; for the common ‘ait: is; dix;
minithed. dné foufthh;:the litmus réddened, and the. lime-water
precipitated, . Mr: Cavenpisu indeed attributes the redness of
4p / the
Mr. Cavenpisny’s Experiments on Air. wk
the litmivis-to fixed air; but he thinks. it; ipsoceeds. fram.a de--
compofition:« of fore part! of. the | vegetable: “pace, as, all veges.
table juices- contain’ fixed air., Me et that, fuch. a, decompofition:
does not take place, 1 think may be: inferred, from, the.,following»
reaforis’:/firft, if the electric fpark. bej taken through, phlogifti-
cated or inflammable air confined! by. litnaus, ‘no rednefs is. \prors
duced, {the air not being, i; the leaf, diminithed. ; | arid, adlyy
ifthe litmus were decomtpofed, ‘inflammable. air -fhould, be. ‘ptos:
duced as' well as ‘fixed air}. and then there, fhould be. ani addition:
of bulk: inftead.of a diminution ;,/but :what fets che, ofigia of,
the fixed air:from the phlogiftication of he common air beyond,
alk doubt 1s;): that-if hime-water be: udéd, andtéad!. pT: dismuss the;
dirninution, is the fame, ahd. the’ lite; fis - sprecipitateds: ee
Mr.CavennisH fays, the -fixed air, proceeds jéithier ; from-fome;
dintan the tube ja Lappofitien,. which, being:neither neceflaty, NOE:
probable; is not admiffible;! or elle: fromfome,combuftible mation!
wa the lime 3 but lime comtains: nO-¢ommbudtible matter, except;
perhaps: phlogifton, which -canhot® produee:.. fixed: aut;-but, by:
uniting to the common ait,according ito: my: {uppofition’; but:
it ig much: more:probable, that the diminution dogs.not-arife from:
any phlogifton in. thé lime, as it is: exadtly: the fame whether:
lime-water be ufed or not; and the lime does not appear to be.
in the leaft altered, and.in. cents {earce any phlogifton..
Sulachcha hth s ie Re abt AR ett é ' MOV UA BAVAT EL SOS We
ay cs
devon l
Of ‘the, din minution n of Commop Ar, ir, yy the ong date i
Ji is} 5 at
sieht _ Mercury and Lead.
+ Piateaibiieadt this diminution” to hen pllogiftications of | ithe
common aii by the procefs of: ‘amalgarnation,: and thei cones:
a, eta and abforption of a ike? On chi Mi Gav
VT TS ST KOTO TRON 't tod’ 2798387 9ON DIS
sng mot o1isarm thore:
>
A ae
“lore
Wim
166 - Mr. Kirwan’s ‘Rites’ on
VENDISH abterveas: ‘that mercury, ‘fouled’ by thecaddition’ of :
<¢ Jead or tin, depofits a powder whicli confifts in great Meafure>
“© of the calx of the'metal : he: found alfo, that fome powder of
this fort contained fixed air ; ‘but it is not clear that ‘this air’
«6 was! ‘ptoduced by the phlogiftication ofthe air in which the:
cer} ifiercury was fhaken,‘as’ ‘the ‘powder was not prepared’ on?
‘¢ purpofe, but was formed from mercury fouled by having»
‘© bécn-ufed for various purpofes, and may therefore contain’
<s other impurities, -befides the metallic calx.” On this I re+)
mark, that Dr. Prigstiey did ‘not indeed at firft prepare this:
powder on purpofe; but he afterwards did fo prepare it (4Prizsr,) .
p- 148, 149.) and obtained a powder exaétly of the fame fort; and:
it is certain that the fixed air found in it proceeded from the»
common air, both becaufe mictallic calces, not formed by amal~.
gamation, will not unite with mercury, as is well known 3 .ands
becaufe ‘this calx cannot be formed by agitation of the mercury;
and lead, in phlogifticated, inflammable, or any other air'whichs
is not refpirable; and the fixed air cannot proceed from:any
impurity, as mercury will not unite in its running form to any:
other but metallic fubftances, which it always’partially dephlo-;
gifticates, like other: menftruums (3 Chy. Dijon, 425.).
Of the Diminution of Refpirable Air by Combuftion, =~
Though I have no doubt but the diminution of refpirable air,
by the combuftion of fulphur and phofphorus, proceeds alfo in
great meafure from the produ€tion~and abforption of fixed air,
yet I avoided mentioning this operation, as the prefence offa
ftronger acid renders the prefence, of a weaker impoffible. to be,
proved, more efpecially; ag: both. thefe acids precipitate lime ,
from lime-water; but the great increafe of weight which the
3 phof-
Mr. CavennisH’s Experiments on Air. 167
phofphoric acid gains:is a {trong additional inducement to think
that it abforbs fixed air. During the combuftion of vegetable
fubitances, I think it highly probable that fixed air is formed,
both from my own experiments on the combuttion of wax can-
dles, and that mentioned in the firft volume of Dr. Priest-
LEY’S Obfervations, p- 1363 but when inflammable air from
metals and dephlogifticated air are fired, as a great diminution
takes place, . and yet no fixed air is found, I am nearly con-
vinced, by Mr. CavenpIsH’s experiments, that water is really
produced ; ; noram I furprized that, in this inftance, the union of
phlogitfton ; and dephlogifticated air fhould form a compound very
different from that which it forms in other inftances of phlo-
giftication, but fhould rather be led to expect it a priort; for in
this cafe the phlogifton is in its moft rarefied known ftate, and
unites to dephlogifticated air, the fubftance to which it has
the greateft affinity, in circumftances the moft favourable to
the clofeft and moft intimate union ; for both, in the a& of
inflammation, are rarefied to the higheft degree ; both give out
their f{pecific fire, the great obftacle to their union, it being by
the inflammation converted into Jenfible heat (a circumftance
which, im my opinion, conftitutes the very eflence of flame); the
refulting compound having then loft the greateft part of its
fpecific fire, is neceflarily reduced, according to Dr. BLack’s
theory, into a denfer ftate, which the prefent experiment fhews
to be water; whereas, in common cafes of combuftion, the
phlogifton being denfer and lefs divided, unites lefs intimately
‘with the dephlogifticated part of common air, confequently ex-
pels lefs of its {pecific fire, and therefore forms lefs denfe com-
pounds, vz, fixed and phlogifticated airs; and fo much the
more, as a great part intirely efcapes combuftion ; but it feems
probable
i BL A
dj ‘i
168 ah Mr Karwaw’s Remarks of)
Pr robable that 4 in very ftrong: sndtbvightinfabiietons th iG
#7 agy9} G3. ahdedd
is “more “perfects and. ‘water formed.
~ Water being then ‘the refult of the clofett na? hort? intimaté
union of de ephlogifticated air and phlogitton, ‘it feems to mie ver
improbable, that it is ever decompote d*by the affinity of any
acid to phlogifton, as all the experiments hitherto made féem
to. prove, “that phlogifton has a ftronger affinity to dephlogiftis
cated air than to any other fubftance, except hot metallic cals
ces; .and thefe, in my opinion, are ‘tncapable of forming any
union with water, except as fat as they are faline, but they
never can be reduced by it. ‘So alfo water is ‘incapable of
‘uniting with any more phlogifton, as fulphur ies beh being
meat {aturated,
Mr. CavennisH is inclined to think, that pure inflammable
dir is not pure phlogifton, becaufe it does not immediately unite
with dephlogifticated air, when both airs are fimply mixed with
each ather; this reafon feems to me of no moment, becaufe f
fee feveral other fubftances, that have the f{trongeft affinity to
each other, refule to unite fuddenly, or even at all, through
the very fame caufe that dephlogifticated and inflammable airs
refufe to unite ; ; ‘VIS on account of the f{pecific fire which they
contain, and muft lofe, before fuch union can take place: thus
fixed air will never unite to dry lime, though they be’ kept
ever {fo long together; thus, if water be poured on ‘the: ftrong'
eft oil.of. feet they will remain feveral weeks in’ contaét,
without uniting, as I myfelf have experienced; and yet,’ ih
betli cafes, the fpecific fire need be expelled ‘only’ from one of
the fubftances, and not from both: ‘but after a longtime they
will unite ;, fo alfo will inflammable and dephlogifticated air, as
Dr. Paest LEY has difcovered fince his taft publication,
4 That
Mr, Cavenpisn’s Experiments on Air, 169
That phlogifticated air fhould confift of fuperfaturated nitrous
air, I think improbable, as it retains its phlogifton much more
ftrongly than nitrous air, which, according to the general laws
of affinities, it fhould not, if it contained an excefs of phlogif-
ton; and as Dr. PriestLey and Mr. Fontana repeatedly af-
fure us, they have converted it into common air, by wafhing it
in water, in contact withthe atmofphere. Iam, Sc.
Lond
Wee it. R. KiRWAN.
| Vou. LXXIV. Z,
es we
“V. Anfver fo Mr. ‘Kirwan’ Ss eens ase the Acsinveiee ice
Air. ad y Haney Cavendith, st F. R. S. and 8, A.
ae
Read March 4, 1784.
N a paper lately read before this Society, containing many
I experiments on air, I gave my reafons for fuppofing that
the diminution which refpirable air fuffers by phlogiftication,
' is not owing either to the generation or feparation of fixed air
from it; but without any arguments of a perfonal nature, or
which related to any one perfon who efpoufes the contrary doc-
trine more than to‘another. © This being contrary to the opinion.
maintained by Mr. Kirwan, he has written a paper in anfwer
to it, which was read on the fifth of February. As I do not
like troubling the Society. with controverfy, I fhall take no:
notice of the arguments ufed by him, but fhall leave them for
the reader to form his own judgement of; much lefs will I
endeavour to point out any inconfiftencies or falfe reafonings, —
fhould any fuch have crept into it; but as there are two or
three experiments mentioned there, which may perhaps be
confidered as difagreeing with my opinion, I beg leave to fay a
few words concerning them.
Mr. pve Lassone found that filings of zinc, digefted in a
cauftic fixed alkali, were partially diffolved with a {mall effer-
vefcence, and that the alkali was rendered in’ fome mea-
I fure
(Papesies'-
Mr. CAVENDISH’ S Aafwer, &e. I7r
fure mild. This mildnefs of the alkali Mr. Kirwan accounts
for by fuppofing, that the inflammable air; ‘which is ‘fepatated
during the folution, and caufes the effervefcence, unites to the
atmofpheric air contiguous to it, and thereby generates fixed
air, which is abforbed by the alkali. But, in reality, the only
circumftance from which Mr. pe Lassone judged the alkali to
become mild, was its making fome effervefcence when faturated
with acids; and this effervefcence is more likely to have pro-
ceeded from the expulfion of inflammable air than of fixed air,
as it feems likely, that the zinc might be more completely”
deprived of its phlogifton by the acid than by the alkali.
In the abovementioned paper I fay, Dr. Priesriey ob-
ferved, that quickfilver fouled by the addition of lead or tin,
depofits a powder by agitation and expofure to the air, which
confifts in great meafure of the calx of the imperfect metal. .
He found too fome powder of this kind to contain fixed air;
but it muft be obferved, that the powder ufed in this _experi-
ment was not prepared on purpofe, but was procured from
quickfilver fouled by having been ufed in various experiments,
and may therefore have contained other impurities befides the
metallic calces. On this Mr. Kirwan remarks, that Dr.
PrigsTLey did not at firft prepare this powder on purpofe, but
he afterwards did fo prepare it (4 Pr. ‘p. 148. and 149.), and
obtained a powder exactly of the fame fort. It was natural to
fuppofe from this remark, that Dr. PriesrLey muft have ob-
tained fixed air from the powder prepared on purpofe, and that
I had overlooked the paflage ; ; but, on turning ‘to the pages re-
ferred to, I was furprifed to find that it was otherwife, and
that Dr. PriestLey not fo much’ as hints that he poanes
fixed air from the powder thus prepared.
Z 2 oe With
172 _ Mr. Cavennisn’s Anfwer to
With regard to the calcination of metals it may be proper ‘to
remark, that this operation is ufually performed over the fire,
by methods in which they are expofed to the fumes of the
burning fuel, and which are fo replete with fixed air, that it is
not extraordinary, that the metallic calx fhould, in a fhort
time, abforb a confiderable quantity of it; and in particular
red lead, which is the calx on which moft experiments have:
been made, is always fo prepared. There is another kind of
calcination, however, called rufting, which is performed in
the open air; but this is fo flow an operation, that the ruft |
may eafily imbibe a fufficient quantity of fixed air, not-
withftanding the fmall quantity of it ufually contained in the
atmo{phere. |
Mr. Kirwan allows that lime-water is not rendered cloudy
by the mixture of nitrous and common air; but contends that
this does not prove that fixed air is not generated by the union,
as he thinks it may be abforbed by the nitrous felenite produced
by the union of the nitrous acid with the lime. This induced
me to try how fmall a quantity of fixed air would be perceived
in this experiment. I accordingly repeated it in the fame man-
ner as defcribed in my paper, except that I purpofely added a
little fixed air to the common air, and found that when this
addition was ...th of the bulk, or 2,th of the weight of the
common air, ve effect on the lime-water was fuch as could
not poflibly have been overlooked in my experiments. But as
thofe who fuppofe fixed air to be generated by the mixture of
nitrous and common air, may object to this manner of trying
the experiment, and fay, that the quantity of fixed air ab-
forbed by the lime-water was really more than .*.th of the
bulk of the common air, being equal to that quantity over
‘ and
Mr. Kinwan’s Remarks. 173
and above the air generated by the mixture, I made another
experiment in a different manner; namely, I filled a bottle
with lime-water, previoufly mixed with as much nitrous acid
2s is contained in an equal bulk of nitrous air, and having in-
verted it into a veflel of the fame, let up into it, in the fame
manner as in the above-mentioned experiments, a mixture of
common air with .'.th of its bulk of fixed air, until it was
half full. The event was the fame as before; namely, the
cloudinefs produced in the lime-water was fuch that I could
not poflibly have overlooked. It muft be obferved, that in this
experiment no fixed air could be generated, and a full greater
proportion of the lime-water was turned into nitrous felenite
than in the above-mentioned experiments; fo that we may
fafely conclude, that if any fixed air is generated by the mix-
ture of common and nitrous air, it mutt be lefs than >,th of
the bulk of the common air.
As for the nitrous felenite, it feems not to make the effect of
the fixed air at all lefs fenfible, as I found by filling two bottles
with common air mixed with ,2.,dth of its bulk of fixed air,
and pouring into each of them equal quantities of diluted lime-
water; one of thefe portions of lime-water being previoufly
diluted with an equal quantity of diftilled water, and the other
with the fame quantity of a diluted folution of nitrous felenite,.
containing about ,2.dth of its weight of calcareous. earth ;
when I could not perceive that the latter portion of lime-
water was rendered at all lefs cloudy than the former. Though
the nitrous felenite, however, does not make the effect of the
fixed air lefs fenfible, yet the dilution of the lime-water, in
confequence of fome of the lime being abforbed by the acid,
does ; but, I peDeee, not in any remarkable degree.
There
Any. gua
aL ‘Mr. Cavespisu’s Anfwer to
There is an experiment mentioned by Mr. Ktrwaw which, ©
though it cannot be confidered as an argument in favour of the
-generation of fixed air, as he only fuppofes, without any proof,
that fixed air is produced in it, does yet deferve to be taken
notice of as a curious experiment. Itis, that, if nitrous and
‘common air be mixed over dr y quickfilver, the common air is
not at all diminifhed, ‘that is, the bulk of the mixture will be
not lefs than that ef the common air employed, until water is
admitted, and the mixture agitated for a few minutes. .The
veafon-of this in all probability is, that part of the phlogifts
cated nitrous acid, into which the nitrous air is converted; re-
‘mains in the ftate of vapour until condenfed by the addition of
water. A proof that this is the real cafe is, that, inthis man-
‘ner of performing the experiment, the red fumes produced on
mixing the airs remain vifible fot fome hours, but immediately
‘difappear on the addition of water and agitation. :
The moft material experiment alledged by Mr. Kirwan is
sone of Dr. PriEsTLEY’s, in which he obtained fixed air from
a mixture of red precipitate and iron filings. This at firft
feems really a, {trong argument in favour of the generation of
‘fixed air; for though plumbago, which is known to confift
‘chiefly of that fubftance, has lately been found to be contained ~
in iron, yet one would not have expected it to be decom=
pounded by the red precipitate, efpecially when the quantity of
pure iron in the filings was much more than fufficient to fupply
the precipitate with phlogifton. The following experiment,
however, fhews that it was really decompounded; and that’
the fixed air obtained was not generated, but only a by
means of this decompofition.
500 grains of red precipitate mixed with 1ooo of iron iia i
yielded, by the affiftance of heat, 7800 grain meafures of fixed
alr,
Mr. er § Remarks. ge
air, fe Gos 24.00 me a mixture of dephlogifticated and inflam-.
mable air, but. chiefly the latter. The fame quantity of iron.
filings, taken from the fame parcel, was-then diffolved in di-
luted oil of vitriol, fo as to leave only the plumbago and other:
impurities. Thefe mixed with 500 grains of the fame red
precipitate, and treated as before, yielded gz200 grain mea-
fures of fixed air, and:4200 of dephlogifticated air, of an in-.
different quality, but without any fenfible mixture of-inflam---
mable air. It appears, therefore, that lefs fixed air was pro-
duced when the red precipitate was mixed with the iron filings.
in fubftance, than when mixed only with the plumbago’ and:
other impurities; which fhews, that its production was not:
owing to the iron itfelf, which feems to. contain. no fixed air, ,
but to.the plumbago, which contains a great deal. The rea--
fon, in all probability, why lefs fixed air was produced in the.
firftt cafe than the latter is, that in the former more of the-
plumbago efcaped: being decompounded by the red precipitate .
than in the other. It muft be obferved, however, that the
filings ufed in this. experiment were mixed: with about ,’,th of.
their weight of -brafs, which. was not difcovered till they were:
diffolved:in the acid, and which makes the experiment lefs de--
cifive. than it would otherwife be. ‘The quantity of fixed’air-
obtained is alfo much greater than, according to Mr. Brere--
MAN’s.experiment,. could. be yielded by the plumbago ufually -
contained in 1000 grains of iron; fo that though the experi-
ment feems to fhew that the fixed air was only produced by~
the decompofition of the impurities in the filings, yet it. cer--
tainly ought to be repeated in a-more accurate manner.
Before I conclude this paper, it may be proper to {um up>
the {tate of the argument on this fubje€&t. There are five me--
thods of phlogiftication confidered by me in my paper on air3-
namely,
196 Mr, Cavenvisu’s Anfwer to
namely, firft, the calcination of metals, either by themfelves
or when amalgamated with quickfilver; fecondly, the burn-
ing of fulphur or phofphorus; thirdly, the mixture of nitrous
air; fourthly, the explofion of inflammable air; and, fifthly,
the electric fpark ; and Mr. Kirwan has not pointed out any
other which he confiders as unexceptionable. Now the laft of
thefe I by no means confider as unexceptionable, as it feems
much moft likely, that the phlogiftication of the air in that
experiment 1s owing to the burning or calcination of fome fub-
{tance contained in the apparatus*. It is true, that I have no
proof of it; but there is fo much probability in the opinion,
that till it is proved to be erroneous, no conclufion can be
drawn from fuch experiments in favour of the generation of
fixed air., As tothe firft method, or the calcination of metals,
there is not the leaft proof that any fixed air is generated,
though we certainly have no dire&t proof of the contrary; nor
did I in my paper infinuate that we had. ‘The fame thing may
be faid of the burning of fulphur and phofphorus. As to the
mixture of nitrous air, and the combuftion of inflammable air,
it is proved, that if any fixed air 1s generated, it is fo {mall as
to elude the niceft teft we have. It is certain too, that if it
had been fo much as .3,th of the bulk of the common air em-
ployed, it would have been perceived in the firft of thefe me-
thods, and would have been fenfible in the fecond though
ftill lefs. So that out of the five methods enumerated, it has
been fhewn, that in two no fenfible quantity 1s generated, and
not the leaft proof has been affigned that any is in two of the
* In the experiment with the litmus I attribute the fixed air to the burning of ©
the litmus, not decompofition, as Mr. Kirwan reprefents it, which is a fufficient
seafon why no fixed air fhould be found when the experiment is tried with air in
which bodies will net burn,
7 others 3
Mr. Kinwan’s Remarks. 177
others; and as to the laft, good reafons have been affigned for
thinking it inconclufive; and therefore the conclufion drawn |
by me in the above-mentioned paper feems fufficiently juftified ;
namely, that though it is not impoffible that fixed air may be
generated in fome chemical procefles, yet it feems certain, that
it is not the general effect of phlogifticating air, and that the
diminution of common air by phlogiftication is by no means
owing to the generation or feparation of fixed air from it.
VoL. LXXIV. Aa
aS Tp
XVI. Reply to Mr. Cavendith’s Aafwer.
By Richard Kirwan, Bf. FRE.
Read March 18, 1784.
MEAN to trouble the Society but with a very few words
in reply to Mr. Cavenpisn’s anfwer, as I confider the
greater part of mine to him as ftill unanfwered.
In the firft place, he fays, that im Mr. Lassone’s experi-
ment the effervefcence proceeded not from any fixed air in the
alkali, but from the further aftion of the acid on the zinc from
which inflammable air was difengaged. But this could not have
happened; for, firft, the zinc, inftead of being further acted on
by the acid, was precipitated according to Mr. Lassone’s own
account (p. 8.); and, fecondly, the acid was only added by
degrees, and undoubtedly would unite to the alkali preferably
to the zinc; therefore it was from the alkali, and not from the
zinc, that the effervefcence arofe.
2dly, With regard to the calcination of lead; though in
England the {moke and flame may come in contact with the
metal, yet in Germany red lead is formed without any com-
munication: between them, according to Mr. Nose, who has
given an ample account of this manufactory (p. 86.). Is not
lime formed in contac with fuel, flame, and {moke? Mr.
Macauer even thinks it probable, that the contact of flame
is hurtful to the prodution of minium (2 Dict. Chy. 639.).
Mr. MonNET madé minium by melting lead in a cuppel, in
fuch
Mr. Kirwan’s Reply, &c. 179
fuch a manner that it was impoflible it could come in conta with.
the leaft particle of flame or {moke (Mem. Turin. 1769, ps71-)s
Mr. Cavennisu exprefles his furprife at my afferting, that
the black powder, which Dr. Prizsriey formed out of an
amalgam of mercury and lead, was exactly the fame as that
eut of which he had extracted fixed air; but, I think, I have
affigned very fufficient reafons for my opinion: how far I was
right will beft appear by Dr. PrresrLey’s own letter, in the
hands of the Secretary, of which the following is an extra. _
‘<I certainly imagined the two black powders you write
<< about to be of the fame nature, and therefore did not at-
“< tempt to extract any air from the latter; but immediately.
“¢on the receipt of your favour of yefterday, I diflolved an
‘‘ ounce of lead in mercury, and expelling it by agitation,
«* put the black powder, which weighed near 12 ounces, into
«< a coated glafs retort; then applying heat, I got from it about
<¢ 20 ounce meafures of very pre fixed air, not .*,th of which,
«¢ remained unabforbed by water.”
Fourthly, it is impoffible to attribute the fixed air, produced
by the diftillation of red precipitate and filings of iron, to
the decompofition of the plumbago contained in the iron:
for the quantity of fixed air produced in Mr. CAveNnDIsH’s
own experiment is more than ¢wice the weight of the
whole quantity of plumbago contained in the quantity of
iron he ufed, fuppofing the whole of the plumbago to.
to confift of fixed air, whichis not pretended ; ; and more than
eight times the weight of the quantity of fixed air which
plumbago really contains. For Mr. Cavenpisu, employed in
his experiment 1000 grains of iron and 500 grains of red pre-
cipitate, and obtained 7800 grain meafures of fixed air, which
are equal to 30 cubic inches, and weigh 17 grains. Now 100
Zara grains
130 _ Mr, Kirwan’s Reply, &c.
grains of bar iron contain, according to Mr. BeErcmaw, at moft,
two-tenths of a grain of plumbago; and confequently 1000 grs.
of this iron contain but two grains of plumbago ; and plumbago,
according to Mr. ScHEELE, contains but one-third of its weight
of fixed air; fo that here, fuppofing the plumbago to be de-
compofed, we can have at moft but feven-tenths of a grain of
fixed air, or little more than one cubic inch. If we fuppofe
the filings to be from fteel, 1000 grains of fteel containing
eight of plumbago, we may have about 2,5 of fixed air, or
about 1,5 cubic inch, and this is the ftrongeft fuppofition,
and the moft favourable to Mr. Cavenpisu. What fhall we
then fay, if we confider that thefe filings were mixed with
copper or brafs which contain no plumbago? and, above all,
that plumbago cannot be fuppofed decompofable by red preci-
pitate, fince even the nitrous acid cannot decompofe it ?
sthly, With regard to the power which nitrous felenite has
of abforbing fixed air, I muft allow the experiments of Mr.
CavenpisH to be juft and agreeable to my own; but it only
follows, that when fixed air is in its na/cent ftate, it is more
abforbable. ‘Thus many metallic calces take it from alkalies
in its mafcent ftate, though in other circumftances they will
take none.
Laftly, the permanence of a mixture of nitrous and come
mon air, made over mercury, cannot be attributed to nitrous
vapour, as vapour is not elaftic in cold; befides, I have often
made the mixture without producing any fuch durable vapour,
and this will always happen, when the nitrous air is made from
nitrous acid fufficiently diluted.
Wane
wh Re
Aree]
XVII. On a Method of defcribing the relative Pofitions and Mag-
nitudes of the Fixed Stars; together with fome Aftronomical
Objervations. By the Rev. Francis Wollafton, LL.B.
Bod Ss. |
Read February 5, 1784.
ROM fome alterations which have of late years been dif-
covered, in the relative pofitions. and apparent magnitudes:
of a few of the ftars we called fixed, it feems not unreafona-:
ble to conclude, that there may be many changes among others. _
of them we little fufpe&t. ‘This thought has led me into a with,,
that fome method were adopted whereby to detect fuch mo-
tions. The firft idea which occurred to me was, to make a
propofal to aftronomers in general; that each fhould undertake
a friéf examination of a certain diftrict in the heavens; and,.
not only by a re-examination of the catalogues hitherto pub-
lithed, but by taking the right afcenfion and declination of
- every ftar in their feveral allotment, to frame an exact map of.
it, with a corref{ponding catalogue; and to communicate their
obfervations to one common centre. This is what I could
be glad to fee begun. Every aftronomer muft with it, and there--
fore every one fhould be ready to take his fhare in it. Such
a plan, undertaken with fpirit, and carried on gradually with:
care, would, by the joint labours and emulation of fo many:
__aftronomers as are now in Europe, produce a celeftial Atlas far
_ beyond any thing that has ever yet appeared.
: f, But
182 Mr. Wotraston’s Method of defcribing the relative
But this would be a work of time, and not within the com=
pafs of every one. What 1 mean now to propofe is more im-
mediate ; and not out of the reach of any who ammute them-
felves with viewing the heavenly bodies, .
Meridian altitudes and tranfits can be taken but once in 24.
hours; and, though accurate, are therefore tedious. Neither
can any re-examination of them be made, but with the fame
Jabour as at the firft. Equatorial fectors are in the hands of
few; and require great fkill. Some more general method
feemed wanting; ‘to difcover variations, which, when detected
or only furmifed, fhould be configned immediately to a more
{trict inveftigation.
Turning this in my thoughts, I confidered, that the noting
down at the time the exact appearance of what one fees, would
be far more fimple, and fhew any alterations in that appearance
more readily, than any other method. A Drawing once made
would remain, and could be confulted at any future period 5
and if it were drawn at firft with care, a tranfient review
would difcover to one, whether any fenfible change had taken
place fince it was laft examined. Catalogues, or verbal Defcrip-
tions of any kind, could not anfwer that end fo well.
To do this with eafe and expedition was then the requifite :
‘and a telefcope with a large field, and fome proper fub-divifions
in it, to direct the eye and affift the judgement, feemed to bid
moft fair for fuccefs.
The following is the method which, after various trials, I
have adopted, and think I may now venture to recommend.
To a night-glafs, but of DoLtonp’s improved conftruGtion,
which magnifies about fix times, and takes in a field of juft
about as many degrees of a great, circle, I have added crofs
wires, interfecting each other at an angle of 45°. More wires
6 may
' Pofitions and Magnitudes of the Fixed Stars, &c. — 18'3
may be croffed in other dire@tions; but I apprehend thefe will be
found fufficient. ‘This telefcope I mount on a polar axis. One
coarfely made, and without any divifions on its circle of. decli-
nation, will anfwer this purpofe, fince there is no great occa-
fion for accuracy in that refpect: but as the heavenly bodies are
more readily followed by an equatorial motion of the telefcope,
fo their relative pofitions are much more eafily difcerned when
they are looked at conftantly as in the fame direction. An ho-
rizontal motion, except in the meridian, would be apt to miflead
the judgement. It is fearcely neceflary to add, that the wires
muft ftand fo as for one to defcribe a parallel of the equator
nearly. Another will then be a horary circle; and the whole
area will be divided into eight equal fefors.
Thus prepared, the telefcope is to be pointed to.a known ftar,
which is to be brought into the centre or common interfeétion.
of all the wires. The relative pofitions of fuch other ftars.
as appear within the field, are to be judged-of by the eye:
whether at 4, or 2, or } from the centre towards the cir-
cumference, or vice verfé; and fo with regard to the neareft
wire refpectively. Thefe, as one fees them, are to be noted.
down with a black-lead pencil upon a large meflage card held
in the hand, upon which a circle, fimilarly divided, is ready
drawn. (One of three inches diameter feems moft convenient.)
The motion of the heavenly bodies in fuch a telefcope is fo
flow, and the noting down of the ftars fo quickly done,. thdt-
there is moft commonly full time for it without moving the
telefcope. When that is wanted, the principal ftar is eafily
brought back again into the centre of the field at pleafure,.
and the work refumed. After a little practice, it is-aftonifhing
how near one can come to the truth in this way: and, though
neither the right afcenfions nor the declinations are laid down
by
184 Mr. Wottaston’s Method of deferibing the relative
by it, nor the diftances between the ftars meafured ; yet their
apparent {tuations being preferved in black and white, with
the day and year, and hour if thought neceflary, written un-
-derneath, each card becomes a regifter of the then appearance
of that {mall portion of the heavens; which is eafily re-exa-
mined at any time with little more than a tranfient view; and
which yet will fhew on the firft glance, if there fhould have
happened in it any variation of confequence. It is obvious,
that very delicate obfervations are not to be made in this way.
In order to explain my meaning more fully, a card fo marked
fhall accompany this paper (fee tab. V. fig. 1.). What I firft hap-
pened to pitch upon was the conftellation of Corona Borealis,
which then fronted one of my windows; and which I have fince
purfued throughout in this method; making the ftars «, 2, y,
Oy’ Copia sn 5 iH.) That Bo ee and +, fae ively central; together
with one or two belonging to Bootes, for the fake of conneét-
ing the whole together. Thefe I have transferred fince on a
fheet of paper, to try how well they would unite into one
map; which they have done with very little alteration. A
copy of that fhall alfo be laid before this Society (fig. 2.).
My defign was, after marking down all fuch ftarsas are vifi-
ble with fofmall a magnifier, to go over the whole again with
another telefcope of a higher power, divided in the fame way $
and after that, with a third and a fourth; fo as to comprehend
every ftar I could difcern. That would difcover fmaller
changes: but it muft be a work of time, if attempted at all.
After fuch a rough map of the conftellation is made, the en-
‘deavouring to afcertain the right afcenfions and declinations of
thefe, may perhaps be advifeable in the next place, rather than
dearching for more.
In
2
Pofitions and Magnitudes of the Fixed Stars, &c. 135
In obferving in this way it is manifeft, that the places of
fuch ftars as happen to be under or very near any one of the
wires, muft be more to be depended upon, than of what are in
the intermediate fpaces, efpecially if towards the edges of the
field: fo alfo what are neareft to the centre, becaufe better de-
fined, and more within the reach of one wire or another. For
this reafon, different {tars in the fame fet muft fucceffively be
made central, or brought towards one of the wires, where any
fufpicion arifes of a miftake, in order to approach nearer to a
certainty: but if the ftand of the telefcope be tolerably well
adjufted and fixed in its place, that is foon done.
In fuch a glafs it is very feldom that light is wanting Gaff
cient to difcern the wires. When an illuminator is required,
I find, that for this purpofe, where you with to fee every {mall
{tar you can, a piece of card or white pafte-board, projecting,
on one fide beyond the tube, and which may be brought for-
ward occafionally, is better than one of any other kind. By
cutting acrofs a {mall fegment of the object-gla{s, it throws a
fufficient light down the tube, though a candle is at a great
diftance ; and one may lofe fight of that falfe glare when one
pleafes, by drawing back the head, and moving the eye a little
fide-ways, and then one fees the {maller flars juft as well as if
no iljuminator were. there.
This then is the method I would recommend to the pm CHeal
aftronomer, for becoming acquainted with the appearance of
the ftars, and fetting a’ watch over the heavenly motions.
After a very few trials, every one would find this eafy. And if
each perfon of every rank among aftronomers would take a
conftellation or two under his care, the numbers who could
undertake it in this: way would compenfate for the defects of
a plan which cannot afpire at’ great accuracy. ‘The labour of
“Vou: LXXIV. Bb | it,
186 Mr. Wotraston’s Method of deferibing the relative
it, even at firft, is but little: It has coft me more time indeed
than T ought commonly to allot to mere amufement ; becaufe
I had my apparatus to contrive, and feveral different and fruit-
lets fchemes to try, before I could fatisfy myfelf. But a quar~
ter, or at the moft half, an hour is generally fufficient for the
marking of one pretty full card in this way: and when once
the cards are marked, and a general map of the conftellation is
formed, a little time given to it in a fine evening, to examine
whether the ftars on fuch or fuch a card remain in their formér
polition, is little trouble indeed. Perfeverance is moft likely to
be wanting, and therefore muft be determined upon; becaufe,
after finding things time after time juft as they were, one’s
hopes of difcovering any thing new will flacken. But the dif-
ferent ftate of the air, or of one’s own eye, will ‘frequently
occafion a freth ftar to become vifible, or a {mall one which
had been noted down to feem to have difappeared; and fuch a.
mere accident will ferve to re-kindle the defire of purfuing it.
Befides, if we obferve no change after a tolerable interval of
affiduous fearch, we may at any time turn to another conftel-
lation: yet ought we never to abandon the former entirely,
after having once publickly undertaken it, without giving no-
tice of our fo doing.
In the cards or maps, it may be obferved, I have not marked
the refpective fizes of the ftars. Nor have I diftinguifhed them
in any way, excepting a few of them with BayeEr’s Greek
letters. It was becaufe I have not hitherto fatisfied myfelf how
to do it. Some method mutt be ufed by every one, to defcribe
to himfelf what he means; but, in laying any thing before the
public, a deference ought to be paid to what has been done by
others. The calling any ftar by a new name would breed con-
fufion: and as I was defirous this fhould appear before this
Society
Pofitions and Magnitudes of the Fixed Stars, &c. 18
Society in its firft rude form, that a judgement might be made
from it how far fuch a {cheme would promife fuccefs, I was
unwilling to look into catalogues or capital maps for the num-
bers or names of the ftars, left I fhould be tempted to adapt
the pofitions of what I had obferved to what I there found fet
down by more able aftronomers. Nothing, therefore, but a
hemifphere of SENEx has been confulted, juft for knowing
how far the conftellation is ufually reckoned to extend, and
what are BAYErR’s references. |
Should this plan meet with approbation, I fhall be happy to
have propofed it; and will endeavour to forward it in any way
that ihall be judged proper: or fhould any other be preferred,
which is within the abilities and leifure of one who is engaged
in another profeffion, I fhall be as happy to lend what affiftance
Ican to it. My aim is only, to render fuch obfervations as I
am capable of making, ufeful to fcience.
Before I conclude on this head, give me leave to add a few
hints. Whether this method be followed, or any other, if a
general plan be fet on foot, whoever undertakes a conftellation,
or diftri&t, fhould determine to examine it with as great accu-
racy as he can; yet never be afhamed to let others know of
-his miftakes. ‘The error of one proves a caution to another.
Such a rough {ketch, once made, will be found of great ufe to
moft of us, in knowing which ftar next to examine with
greater care. He who can do no morethan this, will do a ufe-
ful work by going thus far: and his frequently {weeping over
his diftriét in this way, may lead him to a difcovery which
might efcape a more regular aftronomer. But whoever can,
ought todo more. By degrees the exact pofitions of every ftar
he has noted down may be afcertained, by the method practifed
by Mr. De ta Cariuein his Southern Hemifphere, or by any
| Bba2 other
188 Mr. Wotraston’s Method of defcribing the relative
other which fhall be efteemed more convenient. Every one,
indeed, muft ufe fuch inftraments as he can procure: but affi-
duity can do more with indifferent ones, than will ever be ac-
_ complifhed with the very beft without it. Whatever references
_ are made for one’s own convenience, when a map and catalogue
are give: to the public ftock, the old letters and numbers
ihould be retained as far as they go: though yet notice fhould
be taken, where the magnitudes of the ftars at prefent do not
appear to correfpond with the order in which they have been
laid down. | |
To render this more’ complete, it were to be wifhed, that
each fhould give in a copy of his original obfervations, with an
account of the inftruments he ufed; fince they ought to be
preferved as data from whence his deduétions were made,,
which may then be re-examined at any future time. Yet muft
it be defired, that no one would truft himfelf without carry-
ing on his calculations as faft as the obfervations are made
they will otherwife multiply upon his hands till the labour will
difhearten him from attempting it at all. A heap of crude,
undigefted obfervations would be an unwelcome prefent to the
public.
Having thus ftated this Propofal, I fhall leave it to be pro-
ceeded upon, or not, as fhall be feen proper: And will now
only fubjoin a Lift of fuch occafional obfervations as I have had
opportunity of making, fince the laft which I communicated to
this Society. Ifind, indeed, that itis much longer than I had
apprehended: but asI perceive fome aftronomers abroad have
referred to a few of thofe which have been honoured with a
place in our Tranfactions, it may be as well to follow it up.
An obfervation retained among one’s own private papers I hold
to be of little ufe.
One
Pofitions and Magnitudes of ihe Fixed Stars, &c. 189
One thing let me defire Foreigners to remark: that the re-
gifters I gave of the going of my clock were meant only as
the relations of a mere faéf; that a clock, of fuch a conftruc-
tion, kept or altered its rate fo or fo. They feem to have un-
derftood it as an account of a capital clock, by valuing them-
felves upon fome of theirs going better. The time-keepers in
moft of our Obfervatories are far more accurate; but, excepting
thofe of the Royal Obfervatory at eae their accuracy
is not made public.
Another remark it may alfo be proper to make; that, fince
my former papers, the longitude of this place has been afcer-
tained by comparative obfervations .on the burfting of fome
rockets, let off on purpofe; which, on a mean of feveral,
turns out to be 19”’,02 in time E.of Greenwich Obfervatory ;
that is, it may hereafter be confidered as 19”, inftead of
18’’,6 as I had before calculated it trigonometrically ue the
bearings.
Observations
190 Mr. Wouraston's Afronomical Obfervations.
Obfervaiions made at Chiflehurft, im Kent, longitude 19” in
time Haft of the Royal Obfervatory at Greenwich, and latte
tude 51° 24’ 33 North.
Eclipfe of the moon, ¢ July 30, 1776: obferved with
4 3% feet achromatic telefcope, and a power magnifying
29 times (that is, a fingle eye-glafs belonging to the day-tube)
the aperture of the telefcope being reduced to 14 inches. The
night very clear and ftill.
Apparent time.
pe ane
The beginning not properly obferved.
10 11 31 Grimaldus touched by the fhadow.
lo 12 49 —— covered.
10 14 5 Galileus covered.
10 19 36 Ariftarchus covered.
10 26 o The fpot in Kepler bifected.
10 24 25 Schikardus (but 2.) touched.
TOV PR 620 Rie aie ibilected.
10 27 19 - - - = = covered.
10 28 15 Copernicus touched.
10.20 49... =) =. Vepyered.
10 31 22 Helicon (but 2.) covered.
10 37. 9g Plato touched.
10 37 54+ - covered.
10 38 55 Tycho touched.
Io 39 39 «- = «-_=«Cbifected.
10 40 25 + = covered.
Manijius ©
Mr. Woiuaston’s Afronomical Obfervations, 191
Apparent time.
h.
$2)
Io
Io
10
IO
EE
EF
It
It
If
iI
TZ
¥2.
12.
I2
13
13
13
?
43
46
48
55
58
Q
I"
16 Manilius covered.
51 Menelaus covered.
5 Dionyfius covered.
_ 4 Cenforinus covered.
57 A point (Promontorium acutum, I believe) touched:
21 A fpot between M. Foecunditatis and M. Néétaris
touched.
a 23 M. Crifium touched.
NI Oo
28.
55 >=) 4s, -. aeovered.
57 The eclipfe feemingly total.
11 The moon covers a {mall ftar near her fouth lmb.
_ The ftar hangs on the limb, before it difappears.
17 She covers another ftar a little fouth of her centre.
This vanifhes inftantaneoufly.
Thefe occultations were obferved with arother
power of the fame telefcope; which is ufually
reckoned 100, and which I have formerly fo
ealled; but which on an accurate examination
really magnifies almoft 75 times.
The emerfions of thefe ftars were not obferved.
o judge the beginning of the emerfion to be about
this time; but cannot be certain.
1 Grimaldus quitted by the fhadow.
25 Ariftarchus quitted.
22 Kepler bifected.
15 Tycho begins to emerge.
9 - - bifected.
53 - - emerges. ‘Tull this time I had wfed the
whole aperture (3,6) having forgotten to reduce
i if,.
192 ur. Wottasron’ s Afronomical Obfervations.
Apparent time.
Me eae 3
it, till the moon’s brightnefs reminded me. Same
power as at firft; that 1s, 29. Sale ee
13 6 51 Copernicus begins to emerge. TS eae
720 - - = feemingly.bifetted. eres
13 8:19 + = =(ieMergesy foi nom hoy or
3 10 27 Helicon emerges. |
13 15 26 Plato begins to emerge.
13 16 31 > ='-) emerges, | 7 i
13 21 30 Manilius emerges.
13 23 54 Dionyfius emerges.
13 24 57 Menelaus emerges.
3 29 47. Cenforinus emerges.
13 31 21 The {pot by M. Resenndege emerges.
13 35 31 The point of Prom. Acutum emerges.
13 37 21+M. Crifium begins to emerge. T
13 40:26 ‘~ =:-= + quitted by the fhadow.
»3 42 0 Theend of the eclipfe.
The air was very clear and ftill the whole time: the
fhadow but ill defined. Indeed, it was little more
than a penumbra; the principal {pots remaining
always vifible on the moon’s dufky face.
+
Eclipfe of the fun’ § June 24, 1778: obferved with a 3% :-feet
achromatic telefcope magnifying 75 times. The aperture
reduced to two inches, to prevent breaking -the: ne:
glaties, . 2a & t
3:41 33,5 Beginning... I fufps& the minute me _be miftaken,
33:
ind that it thould he gh. 40’, 33”,5; | Sennen
2 impreffion
Mr. Woivaston’s Afironomical Observations. 193
Apparent time,
h, / 47 *
impreflion could not be 2’, I believe not 1”,
before I obferved it.
5 25 24 End. An undulation on the fun’s hmb; but the
obfervation pretty good.
Eclipfe of the moon ¢ November 23, 1779: obferved with the
fame telefcope, magnifying 75 times. ‘The aperture reduced
to two inches. Night clear and frofty. No wind.
The beginning not afcertained.
13 19 Grimaldus touched by the fhadow.
13 20° "2" =X covered.
17 29 Ariftarchus covered.
20 46 Kepler bifected.
23 40 M. Humorum touched.
27 47 Helicon covered.
28 40 Copernicus and Timocharis both bifected.
29 57 M. Humorum covered.
33 50 Plato touched.
34 27 - - covered.
41 52 Tycho touched.
AZ 8 - - Icovered.
47 11 Plinius (but Q.) covered.
59 «1 M. Crifium touched.
gerd --.- «= , covered.
gage Lhe cclipfe total.
46 23 Moon’s edge begins to emerge.
51 14 Grimaldus begins.
§2 1) 424 emerges.
A haze comes on.
Vor. LXXIV. Ce Kepler
COMYNMIANNTNANNAADAAADDG
194 Mr. Worraston’s Afronomical Odjfervations.
Apparent time. :
A oe
g 2 23::Kepler bife&ted. This not clearly feen. >
g tr 41. Plato begins to emerge. |
9 12 35 - - emerges.
9 13 46 Tycho emerged.
The haze comes on again too much for the obferva-
tion to be purfued any farther. .
Eclipfe of the fun ¢O&. 16, 1781: obferved with the fame
telefcope and magnifying power.
The beginning not vifible ; fun too low.
20 2% 13,5 Theend. Good.
Eclipfe of the Moon x Sept. 10, 1783: obferved with the fame
telefcope, v2. 33 feet achromatic, with the aperture reduced
to two inches; but with a {mall magnifying power of 36.
times, which I had made by Mr. Dottonp for thefe obfer-
vations, and which I found very convenient. Night a little
hazy, but pretty favourable.
33 © Adufkinefs comes on the moon.
45 35 The beginning of the fhadow, I believe.
47 20 A hazinefs obfcures the moon.
50 55 Ariftarchus covered.
52 20 Kepler covered. So it is fet down; but F do not
recollect what I meant by this; whether it might
not be only the fpot in the centre, fo that it
might more properly be called bifefted. ~
Gaffendus
‘Oo ‘oO Oo OO 0
Mr, Wotiaston’s Afironomical Ob/eruviions. 195
Apparent time,
h, 7 ad ‘
9 57 57 Gaffendus covered. Ifufpect the minute here; and
that it fhould be 56’ 57”.
41 Heraclides covered.
\©
in
iS)
42, Copernicus touched.
5 = - - * covered.
26 Helicon covered.
12 Bulialdus covered.
o A hazinefs again.
57 Plato covered.
30 Manilius covered.
54 Tycho touched.
53: - - covered. This doubtful.
10 Menelaus covered.
38 Dionyfius covered.
40 Plinius covered,
med
oO
Mm CO COB YU L
Ln |
O Oo
|
Oy
bat
O
1 ot
oO NJ
| on |
oO O
N
No ofS
A hazinefs again.
25 Cenforinus covered.
34 M. Crifium touched.
45 = =) = | covered. pk
34 Total darknefs, as I judged it.
At toh. a1’ the moon had grown reddifh, and the
eclipfed part become more vifible than before.
After fome time, during the total darknefs, the
moon was barely to be feen. In general, about
the centre, it was darker than towards the cir-
cumference, which wasill-defined. About
12 0 oO The eaftern limb became more vifible, and better
defined, i
Ce2 The
Ln |
oO
Ww
-
|e EE |
Oo oO
Us
on SO
196 Mr. Wotraston’s Affronomical Obfervations.
ce a}
Apparent time.
h,
/
tf
1214. © The light fpreads a great way over the moon from
that fide towards the centre, extending about
two-thirds of her circumference (fee fig. 3.)
The moon feems beginning to emerge. :
Emerfion certainly has begun.
Grimaldus emerged.
Galileus emerged.
Ariftarchus emerged.
Kepler (but Q. this as before).
Heraclides emerged.
Helicon emerged.
Copernicus emerged entirely. ae at
Plato begins to emerge. Be
- - emerges.
Tycho begins to emerge.
- - emerges.
Manilius emerges. a ee
Menelaus emerges.
Dionyfius emerges.
Plinius emerges.
Cenforinus (but 2.) emerges.
M. Crifium begins to emerge.
- = .- . emerges.
The fhadow quits the moon near Langrenus, be-
tween that and M. Crifium. The dufkinefs does
not leave the moon till fome time afterwards, but
I did not wait to obferve it.
The moon was darker during the eclipfe than ufual ;
but the air was not clear enough for any occulta-
tions of ftars to be obferved.
Tranfit
Mr. Wotraston’s Afronomical Obfervations, 197
Franfit of Mercury over the fun’s difk ¢ Nov. 12, 1782: ob-
ferved with the fame telefcope, and a power of 75 times.
The aperture reduced to two inches.
Apparent time.
h. / 4/
251 49 Firft impreffion obferved. It could not be 2” fooner.
“2°54 57 Vhread of light completed; but feen through
clouds. ‘The planet feemed to hang on the fun’s
limb 30’ at leatt.
4 6 o Through a break in the clouds, of fhort duration,
8 feemed to have quitted the fun; but indeed
the clouds. were very unfavourable the whole
time.
Occultation of Saturn by the moon, % February 18, 1775:
obferved with the fame telefcope; and, I believe, the fame
power, with the whole aperture of the object-glafs 3,6
inches; but, I perceive, I have not fet down thefe parti
culars.
9, § 39 Prec. anfa of the ring-im.
9 6. 9g Prec. limb of the planetim.
Subfequent limb not fet down..
g 6 48 Subfequent anfa im.
The moon low at thefe immerfions, and much un-
dulation. The emerfions loft by looking at.a
wrong part of the moon’s difk, except
10 «61 «67 Subfequent anfa emerges.
Night very clear; but the obfervation on the whole
imperfeét,
Occultations
198. Mr. Wottaston’s Afronomical Obfervations.
Occultations of ftars by the moon: obfervad with the fame
telefcope, and a power of 75 times, with the whole aper-
ture of the object-glafs. i
Apparent time.
1775¢ ahae tee a
$Aug. i. Dy Virginis 7 48 17 Both flars vifible when aclond covered
e them, vy Ve
7 49 20 A fhort break; only one ftar vifible.
7 52 15 Another break; but before this the fe-
cond ftar was immerged.
8 48 58,5 Firftxem. good.
8 49 6,5 Second xem. good.
He ih liye 8 54 13 Im. good.
Em. not till the moon was too low.
é Dec. 12. ) Regulus 10 5 46 Em. very good, though the moon low.
1770.
© June 30. Ol adp ft 9 349 Im good; fome flying clouds,
10 6 38 Em,3 perhaps fooner,
1777+
} Aug. 23. D p» Ceti 10 41 17 Im.: themoonlow; night clear and ftill,
Ti 32 10 Em.
I Nov. 15. ) 1 ado Tauri Im. not feen; undulation too great.
7 22 560 Em, pretty good.
©Nov.16. ) Tauri 11 17 1,5Im. good. ( Thefe were obferved with a
12 23 28 Em.good.4 power of 64 times, and an
oblique {fpeculum.
1783.
@ May 16. ) =Scorpii 11 21 49 Im, ties clear and ftill; the obfer-
12 31 49,5 Em.
Ujul 10. ) = Scorpii Im, not feen for clouds.
vations good,
8 43 56 Em.; it might be 1” or 2” fooner; the
moon’s edge ill defined.
é Dec. 30. 2Pifcium 8 3.13 Im, darklimb, very good,
g 8 30 Em. good. It could not be above 1”
fooner, if that. Night very clear and
fill; hard froit; therm, 13°3-
2 Eclipfes
Mr. WotLaston’s Afronomical Observations.
199
Eclipfes of Jupiter’s fatellites: obferved with the fame tele-
{cope and power (that is, 75 times; called ufually 100) and
whole aperture.
Apparent time.
1775+
¢ Sept. 8.
©Oo& 1.
a Nov. 2.
pi 16,
1 Sat.
I Sat.
i Sat.
2 Sate
Dee, 18.
2 Sat.
3 27. 1 Sat.
1776.
© Nov. 17.
1778.
WU May 21. 1 Sat.
2 Sat.
2 June 11. 4 Sat.
b 13. 5 Sat.
4779-
@ Mar. g. 1 Sat.
b May 22.
1781.
U May 24.
a gi.
h June 16.
1782.
h July 20.
2 Sat.
Pioat.
1 Sat.
{ Sat.
3 Sate
2 Sat.
rT Sat.
3 Sat.
h, che ae
TI 33 14
by SI Gia
8 28 2
g ,0%13
10 45 48
II 2 oO
7 348
9 38
919 6
10) 12:3
It 57 35
10 13 13
G 6 42
IE 30 30
Im. flying clouds; obfervation doubtful.
Im, good; unlefs the minute be miftaken.
Im, good,
Im. pretty good; air clear, but a cold in my
eyes rendered the obfervation not fatisfactory.
Em. good,
Em. pretty yood.
Em. good.
48,5 Im.; a fcintillation for fome feconds before it
quite difappeared.
Em..good.
Em. fo near the firft fatellite; as-fcarcely to be’
diftinguifhable from it for fome minutes.
Im, good for the fourth fatellite, yet vifible by
fits for fome feconds longer.
Em. pretty good.
Im.; that is, this was the laft of my feeing it ;-
but, though the night was clear, the fatellite
was too near Jupiter for the obfervation to be
fatisfactory.
Em. good.
Em. very good.
Em. pretty good.
Em.; clouds, but pretty good, -
Em. goed,
Em. good,
Emerfios
Apparent time, ‘a
hee Sides nnjay. | i
@ July 21. 1Sat. 9 39 50 Emerfion; windy; but good.
o{ Aue.90, 1 Sat. ' 8 20 15,5 Em. ) |
2 30. 4Sat. 8 52 19 Em; fatellite feen then, but not diftin® for
fome time.
MO hope
o July 8. 1 Sat, 12 14 13 Im. pretty good.
h Aug. 2. 1 Sat. Q 10 31,5 Em. good.
Dd 25. i.sat. . 9.20/54 Him.
¢ Sept. 26 1 Sat. 6 19 44 Em. pretty good, but twilight ftrong.
$ 30. 3Sat. 10 3 24 Im. It was vifible only by fits for the laf 8’.
Jupiter near a tree.
2@O0& 3. 1Sat. 8 18 oO Em. pretty good; but the moon helow Jupiter.
© 26. 1Sat. 8 39 17. Em. Jupiter low and nearatree; great, undu-
lation,
EXPLANATION OF THE FIGURES IN TAB. Ve
Fig. r. # Cor. Bor, § Aug. 6, 1783, per night-glafs. ‘The *% marked Sept. 24,
was not obferved till that night, but has continued fince, and was only
overlooked at firft,
Fig. 2. A map of 107 ftars, befides thofe marked by Bayer, in the conftellation
of Corona Borealis, or the Northern Crown; together with a part
of Bootes: laid down from obfervations made 1783 with a night-
glafs furnifhed with crofs-wires; as their relative pofitions were eftimated
by the eye.
Fig. 3, The moon as fhe appeared (inverted) % Sept. 10, 1783, about a quarter
of an hour before fhe began to emerge from total darknefs.
ae
Vol LXXIV, Tab. V.p.200.
Philos Trans
Philos Trans Vol LXXIV, Tab. Vifp.200.
iz Giz, = ™
Y= 4 x
| Sf.7. 2, . a. ae
| + & gf Fs * Hg. 2.
) colle
*H
<c *
* , EEK
* —_ a * . Boous
* ss oe ** *
ee cls: is *C ss
. *
*d
2 *K #
* ek a
*
x * . * #
ee *
oy ae) Boots ae
*
*p xo
** * x *
* * *A *
* * -
, * * *
x* ¥ te -
C Se S| bg *, x
*éE ” > *
Gr
Vly. 3
e oe * *
| tA * alee *
) *
| *U
| ° *
i *
| “i
|
| * xo
* a a
. be
pe Sby hd eee
Eo paot ddd
XVII. An Account of fome late fiery Meteors | 5 with Obferva-
tions. In a Letter fromCharles Blagden, M. D. Phyfician to
_ the Army, Sec. R. S. io Sir Jofeph Banks, Bart. P. R. S.
Read February 19, 1784. "
“oTO SIR JOSEPH BANKS, BART. PRS:
DEAR, SIRy-
ROM the papers you: were f good as to put into my hands,
together with fuch other information as I could procure,
the following account of the two moft remarkable of the late
meteors is collected. I am fenfible, that it is. in many refpects
very imperfect ; yet flill it gives a’more fatisfagtory:idea of the
phzenomena than can well be acquired from the-relation of any
fingle obferver, and therefore may not be difagreeable to the
learned Society over which you fo worthily prefide, if no more
perfect account fhall previoufly have been laid before them. »,
~Thefe meteors were cf the kind known to the ancients. by
the names of Aapmadecs, Tso, Bolides, Faces, Globi, &c. from
particular differences i in. their fhape and appearance, and foitie-
times,. 1 believe, | under the general, term of, Comets *; in the
noe Philofophical
iG Anisrorie? sremark, that all the comets feen among them di iappeared without
fetting, wc pe os nal? apes apepavos (Kopatle) ave devoeag aQancbray cp re ume Te agiteles
wore (Meteor. lib. I. c. 6.), feems fcarcely applicable but to tranfitory me-
teors 5 and. many other _expreifions to the fame purpole o occur in that author,
ou. LXXIV. 5S a es | wis PLINY,
202 : Dr. Braopkn’s Account of
‘Philofophical TraniaGtions they are catled indifcriminately fires
batts or fiery meteors; and names of a firailar import have
: been: applied , to them i wi the different, languages | of Eupope ois
1 dhe mott material Gircumftances, obferved of fuch® rheteors
may t be brought, under the follo. wing heads. is ‘Their general
appearaice. 2. Their | path. 3. Their ea or figuie. 4s
ig light and colours. 5. Their height. 6. Their noife.
. Their fize. 8. ‘Their duration. | g., ‘Their velocity.
cy fhall begin with the firtt of ANG meteors, that which was
feen on the 18th of Auguft.
§ 1. Its general: appearances in thefe parts sof, Great Britain
was that of a luminous ball, which rofein the N.N.W. nearly
round, became elliptical and gradually affimed a*tail"as it
afeénded, atid in a certain part of its:courfe feemed ‘toCundergo-
a remarkable change compared to burfting ; afteriwhieh at pro-
eceded no longer'as ‘ai entire mafs, |but was apparently ‘divided
into a great number or a clufteriof ‘balls, fomie larger than the
others, and'all earrying a tail or leaving a train: behind; under
this form it continued its courfe with a nearly equable motion,
dropping or cafting off fparks, and yielding a: prodigious dight,
which illuminated’ all objects toa furprifing: degree ;_ till/having
pafled the eaft, and verging corifiderably'to the fouthward, it
aPggae defcended, and at length was loft out of fight...' The
ee ag SENECA himfelf, though he haa diftinctly enough the difference
between comets and fiery meteors, yet evidently did not know where to draw the
line (compare lib. T. and VII, Queft. Natur.). Even in modern tines, thefe:meteors-
have ftrick fpeétators at firft as comets (Fritzes Medizinifche Annalen, vol. I.
P+ 77-)5 Day, expert aftronomers, as appears by a letter from NATHANIEL PicorT,
Efq, F.R. S. lately read ‘arate the Royal Society. See alfo Mem. “de PAc. des:
Scienc. 1771, p- 688. I have infifted the more on a fubjegt apparently of fo little con=
fequence, i in order to account for the ftrange opinions of the ancients refpedting
comets, which, Ithink, proceeded chiefly from confounding them with thefe fiery
meteors.
time
: | fane late flery Meteors. -. 203
time of its appearance, was 9. bes 16 PM. mean time of the
meridian of. Randers, and it, continued vilible, about half: a
minute. ie ie ; : ‘
ha: How far saath He meteor may have begun I hee no
ce: to determine with precifion 5 s but, as it was feen in
Shetland, and at fea between the Lewes and Fort William, and
appeared to. perfons at Aberdeen and Blair in Athol: afcendin
from-the northward, and to an obferver in Edinbargh as ‘rifing
like the planet. Mars, there can be little doubt but its Kt
commenced beyond the fartheft extremity of this ifland, fome-
where over the northern ocean. General. Murray FE. R,
being then at Athol Houfe, faw it pafs over his head. as nearly
vertical as he could judge, tracing at from about 45° of eleva-
tion north-north-weftward to 30° or 20° fouth-fouth- ealtward,
where a range of buildings intercepted i it from his viewe From
near the zenith.of Athol Houfe, it pafied. on alittle weltward
of Perth, and probably a little eaftward of Edinbur gh s 3 and con-
tinuing its progrefs over the fouth of Scotland, and the weflern
parts of Nerthumberland and the Bifhopric of Durham, , pro-
ceeded almoft through the middle of Yorkthire, leaving the
capital of that. county fomewhat to the eaftward. Hitherto’ its
path’ was as nearly §,S.E. as can be afcertained ; but fomewhere
near the borders of Yorkthire, or in Lincolnfhire, it appears to
have gradually deviated to the eaftward, and in the courfe of
that-deviation to have fuffered the remarkable change already
- noticed under the denomination of burfting.. After this divi- ©
fion, the compact clutter of fmaller meteors feems to have
moved for fome time almoft S.E. thus traverfing Cambridge-
fhire and perhaps the. weftern: confiniés of Suffolk; but gra-
dually recovering its. original direction, it proceeded over Effex
and the Straits of Dover, entering, the continent probably not
Debra dtinavh | _ far
204 Dr. Bracpen’ s Account of
far from Paee. where, as ell as at Calais and Oftend; it
was thought to be vertical. Afterwards it was feen at Bruffels;
Paris, and Nuits in Burgundy *, ftill holding on its courfe to
the fouthward; nay, I have met with an intimation, though of:
doubtful authority +, that it was perceived at Rome. Our in
formation of its progrefs over the continent is, indeed, very
defeGtive and obfcure; neverthelefs, I think, we have fufficient.
proof that it traverfed in all 13 or 14 degrees of latitude; de-
{eribing a track of 1000 miles at leaft over the furface of ‘the
earth; a length of courfe far exceeding the utmoft that =
been hitherto afcertained of any fimilar phenomenon.
To adduce the different accounts from which this path is.
determined, would not only be infufferably tedious, but con-
trary to the intention of this letter, which is to give a fum-
mary view of the whole. They are contained partly in letters.
and partly in the different news-papers of England and Scot-
land, moft of which have been perufed for this purpofe. The
information derived from the news-papers, however incorrect
in the detail, is brought to fome degree of certainty by the
check of comparing them with one another; and their fre=
quent publication in moft places of confequence in this ifland,
procures us advantages on the occafion of fuch extraordinary
phenomena, not enjoyed in former ages, nor even now, to.
the like extent, in any other part of the world.
It feems fcarcely more interefting to trace the path of thefe
bodies with minute precifion, than it would be to mark the
progrefs of a cloud’s fhadow upon the ground; but it is of
confequence to their theory to afcertain well the direGion of
their courfe; and their deviations from a ftraight line, as im-
plying fome particular caufe, fhould be carefully noticed. 1
* Journ. de Paris, Aout 24, 1783. |
q Paxxer’s General Advertifer, October 7, 1783.
have
_ fome late fiery Meteors. 205
have ventured to afcribe fuch a deviation to this meteor, from
the concurrent teftimoay of many obfervers, who fpeak in the
plaineft terms of a manifeft change in its courfe. about the
time it was feen to burft; and their evidence is confirmed by
drawing a line S.S.E. from that part of Scotland to which the
meteor was vertical, for fuch a line is found:to correfpond with
its path as far as Yorkfhire, but in the fouthern parts of the
kingdom falls. great deal too.much to the weftward. That it
afterwards refumed its former courfe is rendered probable from
the teftimony of the obfervers in Kent, who almoft uniformly
mention its difappearance in the S.S.E. as well as from the re-
marks made by feveral perfons near the metropolis, that when
it attained: its) greatef{t elevation, it bore but one or two points.
to. the northward of eaft.
§ 5. This. meteor was defcribed by moft fpectators under.
three different forms, and is thus reprefented. by Mr. Sanpsy
in his beautiful Drawing * ; but the two firft of thofe do not
imply any real variation in its fhape,. depending only on a dif-
ference in the point of view. Accordingly, in the firft part of
its courfe over Scotland, it was feen to have a tail,. and is thus.
defcribed by General Murray when it pafled Athol Houfe.
Two caufes concur in this deception; firft, the fore-fhortening;.
and even occultation, of the tail, when the object is feen nearly
in front; and, fecondly, that the light’ of moft part of the
tail is of fo inferior a kind, as to be difficultly perceived. at a
great diftance, efpecially when the eye is dazzled by the over-
powering brilliancy of the body. The length and fhape of:
the tail, however, were perpetually varying ; nor did the body |
continue always’ of the fame magnitude and figure, but was.
fometimes round, at other times elliptical, with a blunt or
* Since engraved. See alfo the figures tab, IV. of this volumes. : |
pointed)
ach. idiet reat Aicount of
painted: protuberance behind, From fuchi changes of sfigmecniid
this and other: meteors it 1s,_ that: they have been. compared to :
columns. ‘or. pyramids: of: fire, comets, barrels, bottles, flatkss
paper-kites, trumpets, | tadpoles, glafs-drops, quoits, torches,
javelins, goats, and many fimilar objets; whence the multi-
farious appellations given to them is the ancients were ‘bone
rowed. werk
-. Ref{pecting the ok se meteors, it is-here ocala to SiQits
euith between two different parts of which they confift, . The
brighteft portion feems to be of the fame nature as the body,
and indeed an elongation of the matter compofing it; but the
other, and that commonly the largeft portion, might more
properly be. called the train, appearing to be a matter left be-
hind after the meteor has pafled; it is far lefs lummous than
the former. part, and often. only of a dull or dufky red colour.
A fimilar. train or ftreak 1s not: unfrequently left: by one of the
common falling ftars, efpecially of the brighter fort; and vef-
tiges. of it ‘fometimes remain for feveral minutes. It often
happens, that even the large fire-balls have no other tail but —
this train, and ours of the 18th ef Auguft appeared at times te
be in that {tate ; its tail was likewite sit by fome er
to be dpiral.
Under this changeable com) but fill as a Genii body, it
proceeded regularly till.a certain period, when expanding with -
a great-imcreafe of light, it feparated into:a clufter of {maller
bodies or ovals, each extended into a tail and producing a train,
At the fame time a great number of {parks appeared to rflue
from it in various directions, but moitly downward, fome of
which weredo bright:as alfo to leave a fmall train. Moft fire-
balls have fuffered a burfting or explofion of this kind; but
in general they haye been thought to difappear immediately
s, altecwane
\ fomerlate fiery Metedrs..o. 207
afterwards: «This, however; continued, its .cburfe,, becoming
more! conmpac, ior: perhaps re-uniting,;and,/feems to have’ un-
gergone other: Gmiuar:explofons before it, jeft our afland; and
again upomtheccontinent *.: ‘The ditterent accounts: tetid to
fhew, that its firft feparation!or burfting happened fomewhere
ever Lincolnfhire, perhaps near; the commencement: of the
fens.» Many obfervers did-not get fight of it till after this pe-
riod, and therefore never defertbe it. as.a fingle ball.. There
appears tobe fome deception, im conféquence of which {peGa-
tors are led to believe; ‘that aimeteor is extinguithed, by thefe
explofions; for the fame opinion was formed of this in feveral
= its: courfe, a we nee indeiderstive ovidence of
become ssa Gok a time snbsdisealy afer their atic
or merely appear fo'on account of the greater, preceding light;
fince they are’ always :defcribed as.- gga anal: luminovs» the.
inftant they burft rs SOOhE UN sift ibs Sle in !
Tt .is jobfervable,: that the ~~ caer; in. ahaa meteor cor
refpondsiiwith the period in which «it fuffered a deviation from
#ts courfe, as if there was fome conhexion: between thofe two
eircumftances ;) and there are traces of: fomething of the fame
kind having happened ‘to: other: metebrs. If the explofion be.
any fort of effort, we cannot wonder:that the body :fhotld be
moved by. it from ‘a flraight lme ;'but.on theiother thand’ it
feems equally probable, that-if the. ‘meteor be forced, any
_caufe, to change its directions:the : eye thould: b be,ia
ome or feparation of ‘its parts.i) 9 4) éiilog:
OF § 43 Nothing relative to thefe meteors: ficikéea: a Behpidee’
with fo much aftoniffyment as the exceflave light: they afford,
_* For another inftance of repeated explofions Bas Mem, de l’Ac.. des:Scienc..
f 7 s Ps. 23.
fufficient
208 Dr: BLAGDEN’s Account of
fufficient to render very minute objets vifible upon the ground
in the darkeft night, and larger ones to the diftance of many
miles from the eye. The illumination is often fo great as
totally to obliterate the ftars, to make the moon look dull, and
even to affect the {peCtators like the fun itfelf; may, there are
many inftances in which fuch meteors have made a fplendid
appearance in full fun-fhine. ‘The colour of their light is
various and changeable, but generally of a bluith caft, which
makes it appear remarkably white. A curious effect of this
was obferved at Bruffels the 18th of Auguft, that whilft the
meteor was pafling, ‘¢ the moon appeared quite red, but foon
«< recovered its natural light *.” . The brightnefs alone of the
meteor is not fufficient to explain this, for the moon does not
appear red when feen by day; but it muft have depended on the
the contraft of colour, and fhews how large a ‘proportion of
blue rays enters into the compofition of that-light, which
could make even the f/ver moon appear to have excefs of redi
Prifmatic colours were alfo obferved im the body, tail, and
fparks of this meteor, varioufly by different perfons; fome
compared them to the hues ‘of gems. The moment of its
greateft brightnefs feems te have been when it burft the firft
time; but it continued Jong to be more luminous after that
period, than at was before. |
The body of the fire=ball, even before it burft, -did ‘not ap-
pear of an uniform fubftance ‘or: brightnefs, but’ confifted of
lucid and .dull parts, which were perpetually changing their
re{pective pofitions; fo that the whole effeét was to dome eyes
like an internal agitation or boiling of the matter,) and. to
thers like moving chafms or apertures. Similar expreffions
" * From a letter of the Abbé Mann’s, Direétor of the Academy at Bruffels, to
Sir Josepa Banxs, Bart, P. R. S. a
oi0fha have
Some late fiery Meteors. 2og
chaye been ufed in the defcription of former meteors. The
luminous fubftance was compared to burning brimftone or {pi-
_rits, Chinefe fire, the ftars of a rocket, a pellucid ball or bub-
ble of fire, liquid pearl, lightning and eletrical fire; few
perfons fancied it-to be folid, efpecially when it came near the
zenith. Different {peCtators obferved the light of the meteor
to fuffer at times a fudden diminution and revival, which pro-
_duced an appearance as of fucceflive inflammation ; but might,
-in fome cafes at leaft, be owing to the interpofition of {mall
clouds in its path. :
§ 5. When, in confequence of a more accurate attention
to natural philofophy, fuch obfervations were firft made upon
-fire-balls as determined their height, the computers were with
reafon furprifed to find them moving in a region fo far above
-that of the clouds and other familiar meteors of our atmo-
{phere ; efpecially as to every uninformed {pectator they appear
extremely near, or as if burfting over his head, a natural
effect of their great light when feen without imtervening -ob-
jects. The real height is to be collected from obfervations.
-made at diftant flations, which, for the greateft accuracy,
- ought to be fo fituated, that the line joining them may cut the
-path of the meteor at right-angles, and that, at its greateft
‘elevation, it may appear from both of them about 45° above
the horizon, on oppofite fides of the zenith. Alfo two ftations
on the fame fide of its path, if the leaft angle of elevation be
-mot very {mall, and the difference between that and the greateft
angle be confiderable, are by’ no means to be rejected. But
little reliance can be placed upon obfervations of a meteor’s
altitude at any fuppofed period of its courfe, fuch as the mo-
ment of its burfting ; becaufe thofe changes are feldom fo in-
Vor. LXXIV. ec {tantaneous,
‘REO Di. Be Mowatt s Account of :
‘flantaneous, or {een fo much alike by different fpedtators, a
be marked with fufficient certainty.
/Even in proper tations it/rarely happens, char tee alee of
elevation’ can be obferved with that degree of accuracy, which
is neceflary for any certain determination of the height.’ An
eftimate by the eye is doubtful, not only on account of the
“flattened-curve the {ky feems to defcribe, for which the moft
experienced obfervers fearcely ever make a juft allowance, but
likewife of the emotion produced by fuch an unexpected, mag-
nificent, and perhaps alarming fpectacle, which’ renders it
almoft impoffible to be quite collected. Therefore, unlefs an
obférvation be checked by means of a houfe, tree, or fome
‘fixed body, along which the meteor was found to range, it
“muft be received as uncertain. By night the ftars afford ex-
cellent marks, efpecially if the time be known with exaétnefs ;
the brighter meteors, indeed, render thefe faint lights invifible.
for the moment, but here we derive an eminent advantage from
the train, which remains after the meteor is gone, and deli-
neates perfeCtly its track through the heavens. - If no fuch
marks have been taken, the expedient of endeavouring to re-
colle& the part of the fky where it pafled, and afcertaining that
height with a quadrant, may often be ufeful; but there are
many men of fuch a turn of mind, that the original impref-
fion made upon them will be totally perverted’ by their own
fubfequent reflexions and the remarks of others’; in which cafe
fuch an application of inftruments is likely to give a refult
farther from the truth, than their firft immediate judgement,
however vague and hazarded. oh
I am {forry to add, that moft of the obfervations in my pof-
feffion of the meteor which appeared the 18th of Auguft, give
its altitude by eftimation only ; yet ] hope their correfpondence
I with
» fome late fiery Meteors.» 211
with one another will gain them a degree of credit, to which,
if fingle, they wouid not be entitled. . | x
a, In a letter, from Perth in Scotland it is Gide Rea “ a
€* sentleman, who has avery g good eye, obferved the meteor
«* pafs about 6° to the weftw oe of the zenith ;” and a Pro-
feflor in one of the Uni verfities, being at Ardoch on the banks
of the Tweed, about two miles below Dunbarton, judged it to
have ‘‘ at leaft 45° of elevation above the horizon.” Thefe
ees would make its real height 57 ftatute miles,
. At St. Andrew’s in Scotland, ‘‘ it was not quite vertical,
“a he according to fome was 20° or 2 5° from the zenith, ac-
“cording to others not fo much.” Taking the greateft of
thefe diftances as neareft the truth, fince we are ufually led to
eftimate altitudes greater than they really are, this obfervation,
calculated with that of Ardoch, gives 60 miles for the height.
_ For the communication of thefe obfervations, collected by
his friends, I am indebted to General MELVILL FR, o>
At Edinburgh the meteor pafled very near the zenith, in
which cafe a deviation of a few degrees is rw pereetol
to a common eye.
The rev. Mr. Watson of Whitby, in a letter to hand
Muicrave V.P.R.S. is very confident, that the greateft
altitude of the ce which pafied to the weftward of his
zenith, was 60°. Mr. Epceworrtu F.R.S. in his letter to. you,
Sir, ftates its elevation at Edgeworth’s- -Town near Mullingar, i in
Treland, as ro° or 12° above the eaftern horizon. Thefe obferva-
tions, calculated ftri€tly from the latitudes and longitudes with
the allowance for the curvature of the earth, as indeed, were
all the reft where the difference would be fenfible, give 57
miles for the height of the meteor.
Bez | 4. In
212 Dr. Bracpen’s Account of
4. In the Morning Chronicle of Sept. 19. is ‘inferted a letter
from Newton Ardes, 7 miles eaft of Belfaft, in Ireland, cor-
-sefponding fo well with Mr. Epczwortu’s in the defcription
of the meteor, as to appear very good authority. The altitude
is there given as 16°, whence a height of 58 miles with the
obfervation at Whitby.
5. Mr. More, Secretary to the Society for the encourage=
ment of Arts, Manufactures, and Commerce, faw the meteor
as he was riding about three miles $.W. of Brofeley in Shrop~
fhire, and judged it to be elevated 35°. By a perpendicular
drawn from this fpot to its fuppoted path in Lincolnfhire, its
height came out 59 miles. ae |
6. ‘The altitude of 25° determined at’ Windfor I take to be
one of thofe on which moft reliance can be placed, becaufe the
gentlemen prefent, two ‘of them Fellows of the Royal ‘So-
ciety, were remarkably well qualified for fuch an’ eftimation.
The letter you received, Sir, from Profeffor ALLAMAND of
Leyden, mentions that the meteor was feen there about 30°
above the horizon, and the terms in which it is deferibed in
the Dutch news-papers * agree with this account. Its height
hence calculated appears to be 58 miles. ,
>. Mr. THomas’Squire, of. Folkftone, obferved the meteor
over his houfe, as he was in the pofture of leaning back againft
a hedge; he afterwards tried “ its'ranging with the roof by a
‘¢ quadrant, and found it 68°F above the horizon.” Reducing
this obfervation to the perpendicular dropped from Windfor on
the path of the meteor, its height comes out 54 or 55 milés.
Mr.’ Squrre’s altitude, determmed by a fixed object, ‘is con~
firmed by the eftimate of feveral perfons at Ramfgate.
* Amfterdamifche Courant, Aug. we 1783.
4 3. The
[ome late fiery Meteors. 2.13
8. The meteor was feen by Mr. Srzevens F. RB. S,
Hampftead near London, moving along over the top of a row ‘i
trees. Mr. Cavenpisu F.R. S. having taken the altitude of
thefe trees with a quadrant, found that of the higheft, as feen
from the part of the garden-walk oppofite to it, tobe 33°;
which correfponds very well with the other obfervations, and
confequently gives the fame height for the meteor. Mr. Stzs-
vens kept his eye upon it conftantly, whilft he pafled sbi
along the walk.
This agreement of the different altitudes is nearer than
could be expected; yet I know of no contradictory obfervations
of any authority, except fome made near Plymouth and in
Cornwall, where the meteor being pretty near the horizon, its
altitude,’ as will commonly happen in fuch cafes, is given too
great. The effect of. this, however, would be to thew, that
the meteor was higher ; and therefore, I. think, we may fafely
conclude, that it muft have been more than 5° miles above the
furface of the earth, in a region where the air is at oe 30000
times rarer than here below.
Contrary to what has been afferted of moft other fire-balls,
this of the 18th of Auguft appears by the preceding obferva-
tions to have kept on in a parallel courfe, without any defcent
otapproach toward the earth. It may be much queftioned,
whether fucha defcent has been proved many former inftance,.
‘The meteor defcribed by Sir: Joun Prineze has been cited as.
the moft certain example; but any perfon who carefully exas
mines the obfervations themfelves, as'ftated in the 51{t volume
of the Philofophical Tranfactions, will find them totally in-
adequate for fuch a conclufion; its height feems to. me deter.
mined only in one part of its courfe, Die, Ifland-Bridge
and.
S cea
- OF ip Dr. Buacpen’s Account of a
and Ancram, and was there from 48 to 50 miles *. M, Le
Roy fuppofes the fire-ball feen July 17, 1771, to have been
samiles high when it began, and 27 at its explofion +; but
does not give the facts on which his calculation is founded,
Every philofopher muft be ftruck with the agreement of
thefe meteors in their diftance from the earth, . itt beyond the
limits of our crepufcular atmofphere. ‘
§ 6. That a report was heard fome time after the meteor of
the 18th of Auguft had difappeared, is a fa& which refts
upon the teftimoty of too many witnefles to be controverted,
and is, befides, conformable to what has been obferved in moft
other inftances. In general it was compared to the falling of
fome heavy body ina room above ftairs, or to the difcharge of
one or more large cannon at a diftance. That rattling noife,
like a volley of fmall arms, which has been remarked after ©
other meteors, does not feem to have been heard on this occas
fion. From a comparifon of the different accounts, it appears
as if the report was loudeft in Lincolnfhire and the adjacent
countries, and again in the eaftern parts of Kent; in the inter-
mediate places it was fo indiftinét as generally not to have been
noticed, and all obfervers of credit in Scotland deny that they
heard any thing of the fort. If, therefore, this report be connected
with the burfting of the meteor, I fhould be inclined to fuppofe,
that found was produced two feparate times, namely at the firft
explofion over Lincolnfhire, and again when it feemed to butft
foon after entering the continent. Ingenious men have ayailed
themfelves of this found, to calculate the diftance and height
of meteors; and the exactnefs attained by this method, in the
computation of the late fire-ball from the report heard at
* Phil. Tranf. vol. LI. p. 241. and 274.
+ Mem. de I’ Acad, des Scienc, 1771, p. 676. ;
Windfor,
fame late fiery Meteors. 2ne
Windfor*, is very remarkable; but in general the accounts dif-.
agreed fo much, that it would have been impoflible to conclude
any thing from them. Perhaps too the method itfelf is lefs
certain than has been thought; for as the propagation of found,
and with intenfity too, in air rarefied 30000 times, prefents
great difficulties in theory, though it may be in.fome meatfure
explicable from the vaft bulk of the meteor, and the large
quantity of this rare air it may therefore difplace by a fudden
expanfion ;.I think it not improbable, that fome hitherto un-
perceived circumftance comes into play, by which the whole
effet may be modified: for inftance, if matter ‘belonging to:
the meteor itfelf be what conveysthe found to our lewer atmo-
fphere, it may either admit found to be propagated through. it:
at a different rate than through common air, or it may move
much fafter than found travels, as the entire meteor certainly
does, and carry on the fonorific vibrations with it. Moreover,,
we cannot be fure what is the velocity of found in air fo much
rarer than where our experiments have been made. For thefe
reafons, while we diftruft calculations of meteors founded on:
the progrefs: of found, we fhould be particularly: careful-to note:
down the intervals, and all the circumftances, as they may lead:
to very curious difcoveries. The effect of the noife is,. fre-
quently, to produce fuch-a fhaking of the doors, windows, and:
the whole houfe, as is. miftaken for an earthquake. |
Befides the report as of explofions which was heard afer the-
‘meteor, another fort of found was faid to attend it, more:
‘doubtful in its nature, and lefs eftablifhed by evidence ; I mean,,
a kind of hifling, whizzing, or crackling, as it pafled along.
That found fhould be conveyed to us in an inftant from a. body:
above 50 miles diftant, appeaxs fo irreconcilable to all. we
know of philofophy, that perhaps we fhould be juftified in:
® See p, 144. of this volume, ;
umputing.
216 Dr, Buacpen’s Account of
imputing the whole to an aifrighted imagination, or an illufi 1018
produced by the fancied analogy of fireworks... The teftimony
in fupport of it 1s, however, fo confiderable, on the occafion
of this as well as former meteors, that I cannot venture to
reject it, however improbable it may be thought, but would
jeave it as a point to be cleared up by future obfervers. bs?
§ 7. To determine the bulk of the fire-ball, we muft not
only have calculated its diftance, but alfo know the angle un-
der which it appeared. For this purpofe the moon is the ufual
term of ‘comparifon; but as it was thought, at very different
‘diftances, to prefent a difk equal to that luminary’s, and the
fame expreflions have been applied to meft preceding fire-balls, I
‘conceive this eftimation rather to be a general effect of the
ftrong impreffion produced by fuch fplendid obje@s on the
mind, than to convey any determinate idea of their fize. How-
ever, if we fuppofe its tranfverfe diameter to have fubtended
an angle of 30’ when it pafied over the zenith, which probably
is not very wide of the truth, and that it was 50 miles high,
it muft have been almoft half a mile acrofs. ‘The tail fome-
times appeared 10 or 12 times longer than the body ; but moft
‘of this was train, and the real elongation behind feems feldom
to have exceeded twice or thrice its tranfverfe diameter, con>
dequently was between one and two miles long. Now if the
cubical contents be confidered, for it appeared equally round
‘and full in all directions, fuch an enormous: mafs, moving
with extreme velocity, .affords juft matter of aftonifhment.
§ 8. The duration of the meteor is very differently flated,
partly becaufe fome obfervers had it in view a much longer
time than others, and partly becaufe they formed different
judgements of the time. Thofe who faw leaft of it feem to
‘have perceived its illumination about ten feconds, and thofe
who
Jome late fiery Meteors, - 217
who faw moft of it about a minute: hence the various ac-
counts may in fome meafure be reconciled. Mr. Herscuer
F.R. S, at Windfor, muft have kept it in fight long after other
obfervers had thought it extinét: for though, probably, he
did not fee the beginning, as it never appeared to him like a
fingle ball, he watched it as much as ‘ forty or forty-five
** feconds, the laft twenty or twenty-five of which it remained
‘¢ almoft in one fituation, within a few degrees of the hori-
“zon.” This confirms the foreign accounts of its long pro-
grefs to the fouthward.
As fearcely any one had fufficient prefence of mind to mi-
nute the time by his watch, the periods given for its duration
are moftly by guefs. To corre&t this rude conjecture, it has
been propofed, that the obferver fhould endeavour to pafs over
the time in his own mind as well as he can by recollection, -
' whilft another perfon filently marks the feconds with a watch,
This may do fomething, but ftill leaves the matter very uncer-
tain, as the nature of the emotion felt by the {pectator while it
was pafling will caufe the impreffion of a longer or fhorter
time to be left upon his mind; and the formal procefs of re-
collection 1s fo tedious, that I believe the duration will in this
way generally be made too fhort. Mr. Herscurr, at my
requeft, was fo good as to act over his obfervation, with the
pofitions and geftures he was obliged te employ ; and this feems
likely to come nearer the truth than a fimple effort of the mind
at recollection. But the fureft method would be, to repeat
any uniform aétion in which the fpectator might have been
engaged at the time; as, for inftance, to walk over the fame
fpace of ground that he pafied while the meteor was in fight.
~§ 9. From the apparent motion of the meteor, compared with
its height, fome computation may be formed of its aftonifhing
wer, LXXIV. ror velocity.
218 Drv BuaGpen’s Account of i
velocity. As at the heizht of 50 .miles above, the furface of
the earth, it. might be vifible from the fame flation; for artrack *
of more than 12090 miles,.and the longeft- continuance of its.
illumination. fearcely. exceeded a minute, we have hence fomie
prefumption that it moved not lefs than 20 miles:in a feconds
The rey. Mr. Warson, in his letter to Lord |MuLtGRave,
fhys, that the arc defcribed by it whilft in his view could not be
le/s than 70° or 80°, and yet the time could not exceed 4!’ or 5!’ at
mof. ‘This, with an altitude of 60°, and height of 50‘ miles,
gives for its velocity about 21 miles in a fecond. ‘The obferver
at Newton Ardes eftimated its motion to be 10° zm a fecond, at
the altitude of 16°; this would make its velocity 30 miles in a
fecond. Mr. Herscuet found it defcribe am arch of 167°
during the 40 or 45 feconds he obferved it, which gives a velo-'
oa ee
city. of more ‘than 20 miles in a fecond. Finally, Mr.
Ausert F.R.S. thought it defcribed an arch of 136° of azi-
muth in 10 or 12 feconds, which would make its velocity above’
40 miles in a fecond. Iam fenfible of the objeCtions that may
be made to all thefe computations; undoubtedly they are too
vague; and yet, all taken together, perhaps they may have
fome weight, efpecially as they correfpond fo well with the
different phenomena of the meteor’s duration, and other fire-
balls have been computed to move as faft*. Stating the velo-
city at the loweft computation of 20 miles a fecond, it exceeds
that of found above go times, and begins to approach toward
that of the earth in her annual orbit. At fuch a rate, it muft
have paffled over the whole ifland of Great Britain in lefs than
half a minute, and might have reached Rome within a minute
¥* See Mem. de l’Acad. des Scienc, 1771, pe 678. Phil. Tranf. Ww 341. and
360. and vol. LI. p. 263, &c,
5 afterwards, -
— fome late fiery. Meteors. \ 219
afterwards, er in feven: minutes: have traverfed. the whole dia-
meter of the eatth’h ¢i. Lega |
From ‘dae calculation. it will: ie evident, that there is little
chance of determining the velocity of meteors from the-times of
their pafling the zenith of different places ; and that therefore we
mutt. principally depend on obferving carefully; with a watch
that fhews feconds, their apparent eee plaauiase heavens.
eas -
PaaS
oe
DE: as ball aig appeared on i 4th of. O&ober, at 4a"
pait { fix in the evening, was much fmaller than that already de-
{cribed, and of much fhorter duration. It was firft perceived
to the northward asa ftream of fire, like the common fhooting
flars, but large; and haying proceeded fome way under this
form, it fuddenly burft out into that intenfely bright bluith
light which is peculiar to fuch meteors. At this period I faw
it, and can compare the colour to nothing I am acquainted
With fo well, as to the blue lights of India, and fome of the
largeft electrical fparks. The. illumination -was very greats
and on that part.of, its courfe where it had been fo bright, a
dufky red ftreak or train was left, which remained vifible per-
haps a minute even witha candle in the room, and was thought
by fome gradually to change its form. Except this train, I
think the-meteor had no tail, but was nearly a round, body,
‘or perhaps a. little elliptical. After moving not lefs than 10°
in this bright ftate, it became fuddenly extin€, without any
appearance of burfting or explofion.
This meteor was feen for fo fhort a way, that it is fearcely_
pofhible to determine the direétion of its courfe with accuracy ;
but as in proceeding to the eaftward it very perceptibly inclined
towards the horizon, it certainly moved fomewhere from the_
north-weftward to the fouth-caftward. Its duration was fo,
Ef 2 fhort,
/
220 Dr. BLAGDEN’s Account of
fhort, that many perfons thought it paffed in an oppofite direc.
tion; for my own part, I Gand myfelf abfolutely unable to
determine whether the motion was from or toward the §.E.
Some {pe€tators were of opinion, that it changed its courié the
moment it became bright, proceeding no longer in the fame
ftraight line; but my information is not fufficient to determine
this queftion. see
My fituation, Sir, was uitienlsile fortunate for afcertaining
the height of this meteor, as I faw it from your Libraty,
ranging. immediately over the oppofite roof of your houfe.
Hence I find by a quadrant that its altitude, even when it be»
came extinct, could not be lefs than 32°. The upper northern-
moft end of the train it left bore, as I judge by the compais,
about 28° northward of true E.and the lower end about 14°.
I have only one obfervation to compare with this, which was
made by Mr. Boys of Sandwich. He concludes, from the
train I imagine, that ‘‘ it difappeared juft under, and a very
“ little to the weftward” (rather northward) *“ of, the ftar
yin the foot of Cepheus.” At that time y Cephei was about
57° high, and bore above 21° to the eaftward of N. whence the
height of the meteor above the furface of the earth, after all
proper allowances are made*, muft have been between 40 and
50 miles.
As there was no appearance of burfting at the extinétion of
this fire-ball, fo no report was heard after it; nor did any found
attend it.
Some obfervers thought hs meteor alfo near as big as the
moon, but to me it did not appear above one quarter of her dia-
meter, which would make its breadth fomewhat above a furlong.
* It appears from obfervations taken by Gen. Roy, F. R. S, that the bearing
of Sandwich from London is not fo much to the fouthward of eaft, as it is hid
down in our maps,
If
fome late flery Meteors. 22Yr
_ Jf the whole of the meteor’s track be included) it feems to
have lafted as much as three feconds, but in the bright ftate
its duration was lefs than two, I think not much above one.
Suppofing it defcribed an arc of 14° in ri fecond, or, accord-
ing to Mr. Augert’s obfervation, of 25° in 3”, its real velo-
city was about 12 miles a fecond.
Such meteors as thefe, which pafs like a flafh of lightning,
and defcribe fo fhort a courfe, are very unfavourable for calcu-
lating the velocity, but afford great advantages. for determining
the height, as they muft be feen nearly at the fame moment
and in the fame place by the different obfervers.. Other in-
ftances are found of fire-balls beginning with a dull red light
like a falling ftar, particularly the great one of March 19,
1719, treated of fo fully by Dr. Hatiey * and Mr. Wuis-
TON tf.
It is remarkable, that a fimilar meteor had appeared the
fame day, that is, Saturday the 4th of October, about three
in the morning, though, on account of the early hour, it was
feen by fewer {petators. They reprefent it as rifing from the
northward to a fmall-altitude, and then becoming ftationary
with a vibratory motion, and an illumination like day-light ;
#t vanifhed in a few moments, leaving a train behind. This.
fort of tremulous appearance has. been noticed in other me-
teors, as well as their continuing {tationary for fome time,
either before they began to hoot forward, or after their courfe
was ended.
* Phil. Tranf. vol. XXX. N° 350. p. 978.
‘¢ Account of a furprifing meteor feen March 19, 1.719.
3} FIND
a
222 _ Dr, Buacpsn’s Account of
I FIND it, Sir, impoffible to guit this fubje&, without fome
reflexions about the caufe, that canbe capable of producing’
fuch appearances < atan elevation above the earth, where, if the
atmofphere, cannot abfolutely be faid to have oaateds it is cer=
tainly to be confidered.as next to nothing... The firft idea which:
fuggefted itfelf, that they were burning bedies projected with,
fuch, a velocity, was quickly, abandoned, from the want ‘of
any known power to raife them up to that great height, or, if
there, to give them the required impetus; and the ingenuity”
of Dr. Hattey foon furnifhed him with another, hypothefis,:
in which he thought both thefe difficulties obviated. He fup-~
pofes there is no projection of a fingle body in the cafe; but that:
a train'of combuftible vapours, accumulated in thofe lofty regions,
is fuddenly fet,on fire, whence all the phanomena are produced
by the fuccefiive inflammation *. But Dr. Hattey gives no jut
explanation of the nature of-thefe. vapours, nor of-the manner |
in which they -can, be raifed up through air fo extremely rare 3.
nor, fuppofing themrfo raifed, does;yhe account for their regu-.
lar arrangement in. a: ftraight and equable line of fuch prodi-}
gious extent, or for their, continuing to burn in. fuch highly
rarefied air. Indeed, it is very difficult to conceive, how va-
pours could be prevented, in thofe regions where there is in a
manner no preflure, from {preading out on all fides in confe-'
quence of their natural elafticity, and inftantly, lofing that de-.
gree of denfity which feems neceflary. for inflammation. | Be-,
fides, it is to be expected, that fuch trains would fometimes,
take fire in the middle, and {fo prefent the phenomenon of two
meteors at the fame time, receding from. one, another ina °
direct line.
Thefe difficulties have induced other philofophers to relin-
quifh Dr. Hauxey’s hypothefis, and propofe, inftead of it,
. * Phil, Tranf. vol, XXX. N° 360.
one
-
i
pie late fiery Meteors, © a2F
oné of a very oppofite nature, that meteors’are permanent folid
bodies, not raifed up from the earth, but: revolving rounded in
very eccentric orbits; or, in ‘other ‘words, “that they are ter-
reftrial comets*: The objections to this opinion, however,
feem to me equally great. Moft obfervers defcribe the meteors,
not as looking like folid bodies, but rather like a fine luminous
matter, perpetually changing its fhape and appearance. Of
this many defenders of the opinion are fo fenfible, that they
fuppofe the revolving body gets a coat’or atmofphere of elec-.
tricity, by means of which it becomes luminous; but, I
think, whoever carefully perufes 'the various accounts of fire-
balls, and efpecially ours of the 18th of Auguft when it di-
vided, will perceive that their phenomena do not correfpond
with the idea of a folid nucleus enveloped in a fubtile fluid,
any more than with the conjecture of another learned gentle-
man, that they become luminous by means of a contained
fluid, which occafionally explodes through the thick folid outer
fhell +.
A ftrong objeGion to this hypothefis of permanent revolving
bodies, is derived from the great number of them there muft
be to anfwer all the appearances. Such a regular gradation is
obferved, from thofe large meteors which ftrike all beholders
with aftonifhment, and occur but rarely, down to the minute —
fires called fhooting ftars, which are feen without being re-
garded in great numbers every clear night,. that it feems impof-
fible to draw any line of diftinGion between them, or deny
that they are all of the fame nature. But fuch a crowd of re-
volving bodies could {carcely fail to announce their exiftence by
fome other means than merely a luminous train in the night ;
* See a differtation on this fubject by Profeffor Crap, of Yale College, New.
England,
+ Phil, Tranf. vol. LI, p. 267.
65
uw
224 Dr. Buacven’s Account of
as, for inftance, by meeting or juftling fometimes near the
earth, or by falling to the earth in confequence of various ac-
cidents; at leaft we might expeét they would be feen in the
day-time, either with the naked eye of telefcopes, by fome of
the numerous obfervers who are conftantly examining the hea
vens. With regard to thefe falling ftars, it were much to be
wifhed, that obfervations fhould be made upon them by dif-
ferent perfons in concert at diftant flations, for the purpofe of
afcertaining their height and velocity; which would tend very
much to illuftrate all this part of meteorology.
Another argument of great weight again{t the sibecnati
that fire-balls are terreftrial comets, is iT from their great
velocity. A body falling from infinite fpace toward the earth,
would have acquired a velocity of no more than 7 miles a fe-
cond, when it came within 50 miles of the earth’s furface ;
whereas thefe meteors feem to move at leaft three times fafter.
And this obje&tion, if there be no miftake in regard to the ve-
locity of the meteors, as ] think there is not, abfolutely over-
fets the whole hypothefis. |
What then can thefe meteors be? The only agent in nature
with which we are acquainted, that feems capable of producing
fuch phenomena, 1s electricity. Ido not mean that by what
is already known of that fluid, all the difficulties relative to
meteors can be folved, as the laws, by which its motions on a
large {cale are regulated in thofe regions fo nearly empty of air,
‘can fearcely, 1 imagine, be inveftigated in our fmall experi-
ments with exhaufted veffels * ; but only that feveral of the faéts
point out a near connexion and analogy with electricity, and
that none of them are irreconcilable to the difcovered laws of
that fluid.
* How nearly the phenomena of meteors have been reprefented by artificial -
electricity is known from a very remarkable experiment of Mr, Arpen’s. Sce
PuriesTLEY, Vol. V. p. 379.
7 1. Electricity
Some late fery Meteors. . 225
r. Electricity moves with fuch a prodigious velocity, as to
elude all the attempts hitherto made by philofophers to deteét
it; but the fwiftnefs of meteors, {tating it at zo miles a fe-
cond, is fuch as no experiments yet contrived could have dif-
covered, and which feems to belong to electricity alone. This
is, perhaps, the only cafe in which the courte or direction of
that fluid is rendered perceptible to our fenfes, in confequence
of the large {cale on which thefe fire-balls move.
2. Warious eleétrical phenomena have been feen attending
meteors. Lambent flames are defcribed as fettling upon men,
horfes, and other objects*; and {parks coming from them, or
the whole meteor itfelf, it is faid, have damaged fhips, houfes,
é&c. in the manner of lightning +. Thefe facts, I muft own,
are but obfcurely related, yet ftill they do not feem to be defti-
tute of foundation. If there be really any hifling noife heard
while meteors are pafling, it feems explicable on no other fup-
pofition than that of ftreams of eleGtric matter iffuing from
them, and reaching the earth with a velocity equal to that of
the meteor, namely, in two or three feconds. Accordingly,
in one of our late meteors, the hifling was compared to that of
eleCtricity iffuing from a conductor {. The {parks flying off fo
‘ perpetually
* PrisstLey’s Hiftory of Eleétricity, p. 352. Mem. de l’Acad. des Scienc.
1771, p. 681, 682. See an odd fact, perhaps of this nature, in PARKER’s
General Advertifer, Dec. 1, 1783.
+ Mem. anc. de l’Acad. de Dijon, tom. I. Hit. p, 42. Phil. Tranf. vol.
XLVI. p. 366. Hift. de l’Acad. des Scienc. 1761, p. 23.
t Chefter Weekly Courant, Auguft 26, 1763. This and many other cu-
rious circumftances, relative to meteors, are fo well exemplified in the follow-
ing obfervation, made feveral years ago by Mr. Rosinson at Hinckley in Lei-
cefterflhire, that I think it worth tranfcribing here, efpecially as it occurs ina
work which few people would think of confulting on fuch a fubje&. ‘* OG. 26,
** 1766, at half paft five in the evening, after a violent ftorm of wind and rain,
_ Mor, LXXIV. Gg ee
aay - Dr. BuaGvEN’s Account of
perpetually from the body of fire-balls, may poffibly have fome —
connexion with thefe ftreams*. Jn the fame manner the found
of explofions may perhaps be eae to us quicker, than if it
were propagated through the whole diftance by air alone,
Should thefe ideas be well founded, the change of dire€tion
which meteors feem at times to undergo, may poflibly be ins _
fluenced by the ftate of the furface of the earth over which
** J obferved a fiery meteor. Its dire&ion was from N.W. to S.E, nearly in a
** horizontal direction ; it paffied very near to me, and was of an elliptical form ;
«its motion about 40° in 2” or 3!’ of time. It was very bright and lucid to
“* appearance like the paleft peauniites and emitted fparks Continually, which
‘
.
formed a kind of tail toward the N.W. which feemed to be extinguifhed at the
<
”
diftance of 2° or 3° from the body; there was a {mall portion that parted from
*¢ ig, The cohefion “of matter was fo great, that it drew a thread of confiderable
4
“
length from the body, before it broke from it. During the paffage there was a
4¢ kind of A:ffing noife, much lke to what we hear from the electrical machine
c
”
when the electric matter 1s running away, or as when it is efcaping from a full
‘‘ charged jar.” Bibliotheca Topographica Britannica, N° VII. p. 81. :
* Hitt, de l’Acad. des Scienc. 1761, p. 28. Mem. de l’Acad, des Science.
1771, p. 682. Extract of a letter from the Abbé Mann, Director of the
Academy at Bruffels, to Sir JosepH Banxs, Bart. P.R.S. §* I fhall only men-.
** tion one fingular circumftance, which was communicated to me by a particular
‘* friend of mine. It happened at Mariekercke, a fmall village on the coafty
** about half a league to the W. of Oftend. The curate of the village was
‘* fitting in the dufk of the evening with a friend, when a fudden light furprifed
“© them, and immediately after a {mall ball of light-coloured flame came through
‘¢ a broken pane of glafs, croffed the room where they were fitting, and fixed
*¢ itfelf on the chink of a door oppofite to the window where it entered, and
e
~
there died gradually away. It appeared to be a kind of phofphoric light,
€¢
w
*¢ that the fire, which had come in through the window, had been detached from a
large meteor in its paffage.”’
How far thefe and fimilar appearances may be owing fimply to the illumina-
tion produced by meteors, fhould be attentively confidered in the inveftigation
of fuch fags. ;
I they
carried along by the current of air. The curate andhis friend, greatly furprifed at.
what they faw, apprehended fire in the neighbourhood ; but going out, found
— fome late fiery Meteors. es,
they are pafling, and to which the ftreams are fuppofed to
reach. A fimilar caufe may occation the apparent explofion,
the opening of more channels giving new vent and motion to
the electric fluid. May not the deviation and explofion which
appear to have taken place iu the fire-ball of the 18th of Au-
_ guit over Lincolnfhire, have been determined by its approach
toward the fens, and an attraction produced by that large body
of moifture?
3. A further argument for the electric origin of meteors is
deduced from their connexion with the northern lights, and
the refemblance they bear to thefe electrical phenomena, as
they are now almoft univerfally allowed to be, in feveral par-
ticulars. Inftances are recorded, where northern lights have
been feen to join and form luminous balls, darting about with
great velocity, and even leaving a train behind like the com-
mon fire-balls*. ‘This train I take to be nothing but the rare
air left in fuch a highly electrified ftate as to be luminous}
and fome ftreams of the northern lights are very much like it.
The aurora borealis appears to occupy as high, if not a high®r,
region above the furface of the earth, as may be judged from
the very diftant countries to which is has been vifible at the
fame time +; indeed the great accumulation of electric matter
feems to lie beyond the verge of our atmofphere, as efti-
mated by the ceflation of twilight. Alfo with the northern
* Hitt. de VAcad. des Scienc. 1705, p. 35. Wuutston’s Account of a
Meteor feen in the Air 1713. Phil. Tranf. vol. XLI. p. 626; and Lill. p. 6?
Alfo a moft pointed fa& in the Act. Liter. Sueciz, 1734, p. 78.
+ BerGman, upon a mean of 30 computations, makes the average height of
the northern lights to be near 70 Swedifh, that is, about 460 Englifh miles.
Kong. Vetenfk. Acad. Handlingar, vol. XXV. p. 193. See alfo Phil. Tranf.
vol, LIV. p. 327. and M. nz Marran’s Traité de l’Aurore Boreale, p. g1.
Ge¢g2 dights
228 Dr. Buacpen’s Account of
lights a hifling noifeis faid to be heard in fome very cold cli-
‘mates; Gmeztin fpeaks of it in the moft pointed terms, as
frequent and very loud in the north-eaftern parts of Siberia * ;
and other travellers have related fimilar facts +.
But,
* Reife durch Siberien, vol. Ill. p. 135. As the whole paffage is very
remarkable, and has never, that I know, appeared in Englifh, I thought the
following tranflation of it might be acceptable.
‘¢ Thefe northern lights begin with fingle bright pillars, rifing in the N. and
** almoft at the fame time in the N.E. which gradually increafing comprehend a
*¢ Jarge {pace of the heavens, rufh about from place to place with incredible velo-
* city, and finally almoft cover the whole fky up to the zenith. The ftreams are
‘© then feen meeting together in the zenith, and produce an appearance as if a
‘¢ vaft tent was expanded in the heavens, glittering with gold, rubies, and fap-
‘¢ phire. A more beautiful fpe&tacle cannot be painted; but whoever fhould fee
‘< fuch a northern light for the firft time, could not behold it without terror.
‘¢ For however fine the illumination may be, it is attended, as I have learned from
‘¢ the relation of many perfons, with fuch a hiffing, cracking, and rufhing noife
‘* throughout the air, as if the largeft fire-works were playing off. To defcribe
‘¢ what they then hear, they make ufe of the expreffion, Spolochi chodjat, that is,
‘¢ the raging hoft is paffing. The hunters who purfue the white and blue foxes
** in the confines of the Icy Sea, are often overtaken in their courfe by thefe
‘¢ northern lights. Their dogs are then fo much frightened, that they will not
*¢ move, but lie obftinately on the ground till the noife has paffed. Commonly
*¢ clear and calm weather follows this kind of northern lights. I have heard this
** account, not from one perfon only, but confirmed by the uniform teftimony
‘* of many, who have fpent part of feveral years in thefe very northern regions,
‘© and inhabited different countries from the Yenifei to the Lena; fo that no
s¢ doubt of its truth can remain. This feems indeed to be the real birth-place
** of the avrera borealis.”
It is here to be obferved, that Gmexin did not colle& the account himfelf, but
extracted it from letters or papers of M. pz L’IsLE DE LA Croyere’s, who was
himfelf far to the northward of Yakuttk, without hearing thefe noifes ; probably,
therefore, it is much exaggerated, though one can fearcely fuppofe the whole
to be fabulous.
+ Mufichenbroeck Introdua&. § 2495. Beccaria dell’ Elletricifmo artif. et nat.
2 Pp. 225.
Some late fiery Meteors. 229
But, in my opinion, the moft remarkable analogy of all,
and that which tends moft to elucidate the origin of thefe me-
teors, is the direction of their courfe, which feems, in the
very large ones at leaft, to be conftantly from or toward the
north or north-weft quarter of the heavens, and iideed to ap-
proach very nearly to the prefent magnetical meridian. 'Fhis
is particularly obfervable in thofe meteors of late years whofe
tracks have been afcertained with moft exactnefs; as that of
November 26, 1758, defcribed by Sir Joun Prinere; that
mrpby i 7; 1771, treated’ of by* Me Le lRoyi;and)this of
the 18th of laft Auguit. The largeft proportion of the other
accounts of meteors confirm the fame obfervation, even thofe
of a more early period *; nay, I think, fome traces of it are
: per-
p- 221. There is now working with Mr. Nairne F.R. S. a perfon of the
name of ARNOLD, who refided feven years at Hudfon’s Bay, the laft three at
*Fort Healey. He confirms M. GmeEutn’s account of the fine appearance and
brilliant colours of the northern lights, and particularly of their rufhing: noife,
which he affirms he has very frequently heard, and compares it to the found pro-
‘duced by whirling round a ftick {wiftly at the end of a ftring. He adds, that-on
converfing about this matter with a Swedifh watch-maker of the name of Linn,
that perfon affured him, that he had heard a fimilar noife in his own country.
Mr. Nairne too, one time, at Northampton, when the northern lights were
remarkably bright, is confident he perceived a hifing or whizzing found.
This hiffing or rufhing noife, as well as that attending meteors in-their paffage,
fuppofing it in both cafes to be real, I would attribute to fmall ftreams of electric
matter, running off to the earth from the great maffes or accumulations of elec=
tricity, by which I fuppofe both meteors and the northern lights to be produced.
Compare M. pe Mairan’s Traité de l’Aurore Boréale, p. 126.
* See Phil. Tranf. and Mem. de l’Acad. des Sciences, &c. I have found, of
an earlier or later period, accounts of more than 40 different fire-balls. Of
thefe above 20 are fo defcribed, that it is certain their courfe was in the above-
mentioned direction; only 3 or 4 feem to have moved the contrary way; and with
egard to the remainder, it is left doubtful, from the imperfedt flate of the rela-
tions..
ene
2
230 Dr. BLAGDEN’s Account of
perceivable in the writings of the ancients*. Whether their |
motion fhall be from the northern quarter of the heavens or
toward it, feems nearly indifferent, as the numbers of thofe
going cach way are not very unequal; I confider them, in the
former cafe, as mafies of the electric fluid repelled, or burfting
trom the great collected body of it in the north; and, in the
Jatter cafe, as mafles attracted toward that accumulation; a
diftinGion, probably, much the fame in effect, as that of pofi-
tive and negative electricity near the furface of the earth.
‘This tendency toward the magnetic meridian, however, |
feems to hold good only with regard to the largeft fort of fire=
balls; the {maller ones move more irregularly, perhaps becaufe
they come further within the verge of our atmofphere, and
are thereby more expofed to the action of extraneous caufes.
‘That the fmaller fort of meteors, fuch as fhooting ftars, are
really lower down in the atmofphere, is rendered very probable
by their {wifter apparent motion; perhaps it is this very cir=
cumftance which occafions them to be {maller, the electric
tions. When we confider that even the meteor of the 18th of Auguft laft was
thought by /ome {pectators to move fouth-weftward, it will rather appear furprifing
that fo many of thefe accounts fhould correfpond, than that a few of them fhould
differ.
* AristoTLE (Meteor. lib. 1. c. 6.) denies that comets, with which I take
meteors to be confounded, are generated on/y in the north; which fhews it to
have been then the prevalent opinion, that they appeared moft frequently in that
quarter. Adan pany oude Tela aAnbes, are ev Ta W%eos aexloy Tord yivelas 0 Koning 0006
So likewife Piiny (lib, II. c. 25-) Xiphias, Difceus, Pitheus doliorum cernuntur
figura, im concavo fumide lucis. Ceratias. Lampadias. Hippeus. Candidug
Cometes. Omnes ferme /ub ip/o /eptentrione, aliqua ejus parte non certa, fed
maxime in candida, que lactei circuli nomen accepit. And Seneca (Queft. Nat.
lib. VII.) Placet ergo noftris, Cometas, ficut Tubas, Trabeique, et alia oftenta
_ ceeli, denfo are creari. Ideo circa feptentrionem frequentifime apparent, quia illic
fluid
plurimum eft aéris pigri,
fone late fiery Mefeors. rn 23%
fluid being more divided im more refifting air. But as thofe
maiies of clectricity, which move where there. is fearcely any
refiftance, fo gerieraliy afle& the direGtion of the magnetic me-
ridian, the ideas which have been entertained of fome analogy
between thefe two obfcure powers of nature, feem not alto-
gether without foundation *.
If the foregoing conjectures be juft, diftin& regions are:
allotted to the eleC@trical phenomena of our atmofphere.. Here-
below we have thunder and lightning, from the unequal diftri-
bution of the electric fluid ‘among the clouds y in the loftier re--
gions, whither the clouds never reach, we have the various:
gradations of falling ftars; tul beyond the limits of our cre-
pufcular atmofphere the fiuid is put into motion in fufficient:
* Tt appears to me more rational to refolve this analogy intoa power of electri--
City to influence magnetifm, than into a fuppofed fimilarity of two fluids; as the:
former can be made evident by our artificial experiments, but there is no proof
of the latter. When fire-balls, therefore, are faid to affe&t: the magnetic meri--
dian, I do not mean that they are drawn in that direction becaufe it is the line of
magnetifm, but rather that the magnetic poles of the earth are thrown into their-
prefent pofition,. by the accumulation and aétion of that very electricity upon
which the fire-balls depend. Should a change be produced by any caufe in the.
place of this accumulation, or the ftate of its motion, it is not improbable, that
the main polarity would be given to other portions of the earth, whence a varia--
tion in the pointing of the compafs would neceffanily enfues, Af Dr..FRANKLIN’s |
hypothefis be admitted, afcribing the eleGtrical ftate of the polar atmofphere - to»
the cruft of ice (a bad conduétor) in thofe regions, it follows, that fhould ice:
form or be colleSted in. one part moré than in another, the atmofphere there-
would become more highly electrical, and, in fo far as the magnetifm is given by-
electricity, the adjoining portion of the earth would acquire a ftronger polarity,.
Now it is certainly worthy of remark, that fince our firft northern navigations, ,
the coaft of Weft Greenland and its furrounding feas have become~ gradually -
More and more inacceffible on account of ice, and that the magnetic. needle.all:
this time has been conftantly changing its variation to the weflward..
mafies:
232 Dr. BuacpEn’s Account of Some late fiery Meteors.
mafies to hold a determined courfe, and exhibit the different:
appearances of what we call fire-balls; and probably at a ftill
greater elevation above the earth, the electricity accumulates
in a lighter lefs condenfed form, to produce the wonderfully
diverfified ftreams and corufcations of the aurora borealis.
I have the honour to be, with the greateft ref{pect,
STR,
Your moft obedient humble fervant, |
C. BLAGDEN.
EWD OF PART I. OF VOL. LXXIVe
MeTriL @SOiR HIC AL
merans ac EOIN Ss.
Poss HR ela) UL,
VoL. LXXIYV. Hh
es ” f ,
() :
a a
SPCR Fp remem
a
PHeTCOsoOPAICA L
TRANSACTIONS,
moYAtT 5S OGI E toy
Loe N 6D. lL ON.
WO EXXIV.* For the Yean 1784.
7 AU VAI = ie al
iO N2DO NN,
SOLD BY LOCKYER DAVIS, AND PETER ELMSLY,
PRINTERS TO THE ROYAL SOCIETY.
MDCCLXXXI¥%s
me NPR Ne eas
VOL. LAXIV: Part. Tf,
XIX. O* the remarkable Appearances at the Polar Regions of
the Planet Mars, the Inclination of its Axis, the Pofi-
tion of its Poles, and its fpheroidical Figure; with a few
Hints relating to its real Diameter and Atmofphere. By Wile
liam Herfchel, E/g. F. R.S. page 233
XX. 4 Defeription of the Teeth of the Anarrhichas Lupus
Linnzi, and of thofe of the Chetodon nigricans of the fame
Author; to which is added, an Attempt to prove that the
Teeth of cartilaginous Fifbes are perpetually renewed. By Mr.
William Andre, Surgeon; communicated by Sir Jofeph Banks,
Bart. P. R. S. p+ 274.
XXI. Abftrad of a Regifier of the Barometer, Thermometer, and
‘Rain, at Lyndon, m Rutland, 1783. By Thomas Barker,
E/q; communicated by Thomas White, E/7. F. R.S. p. 283
XXII.
Co Ook Be
“XXIL On the Period of the Changes of -Light in the Star.
Algol. In a Letter from John Goodricke, E/g. to the Rev.
Anthony Shepherd, D. D. F. R. S. Profeffar of Aftronomy
aé Cambridge. p. 287
XXIII. Experiments and Daeeoate on the Terra Ponderola,
&c. By William Withering, M. D.; communicated 4
Richard Kirwan, E/g. FAR. S. ) Pp: 293
XXIV. Odjfervations du Paffage de Mercure fur fe Difque du
Soleil le 12 Novembre, 1782, faites a l’ Obfervatoire Royal de
Paris, avec des réflexions fur un effet qui fe fait fentir dans ces
mémes Obfervations femblable & celut dune Réfraction dans
l’ Atmofphere de Mercure. Par Johann Wilhelm Wallot,
Membre de I’ Académie Electorale de Sciences et Belles Lettres
de Manheim, Gc. Communicated by Joleph Planta, E/g.
Sec. R. S. Pp» 312
XXV. Thoughts on the confiituent Parts of Water and of De-
phlogificated Air; with an Account of fome Experiments on
that Subject. In a Letter from Mr. James Watt, Engineer,
to Mr. De Luc, F. R. S. Pp. 329
XXVI. Sequel to the Thoughts on the confiituent Parts of Water
and Dephlogifticated Air. In a fubfequent Letter from Mr.
James Watt, Engineer, to Mr. De Luc, FL. RS. p. 354
XXVII. An Attempt to compare and connect the Thermometer for
ftrong Fire, defcribed in Vol. LXXII. of the Philofophical
Tranfactions, with the common Mercurial Ones. By Mr. Jofiah
Wedgwood, F. R. S. Potter to Her Majefty. p- 358
XXVUI. On the Summation of Series, whofe general Term is a@
determinate Funélion of z the Diftance from the firfi Term of —
the Series. By Edward Waring, M. D. Lucafian Profeffor
of the Mathematics at Cambridge, and Fellow of the Societies
of London azd Bononia. p- 385
XXIX,
CeO Niwas IN PS. vit
XXIX. An Account of a remarkable Froft on the 23d of June,
1783. In a Letter from the Rev. Sir John Cullum, Bart.
F. R. S..and S. A. to Sir Jofeph Banks, Bart. P. R. S.
p- 416
XXX. On a new Method of preparing a Teft Liquor to fhew the
Prefence of Acids and Alkalies in chemical Mixtures. By Mr.
James Watt, Engineer; communicated by Sir Jofeph Banks, .
Here. PER. Ss. Pp. 419.
XXXI. An Account of a new Plant, of the Order of Fungi.
By Thomas Woodward, Efq; communicated by Sir Joleph
Banks, Bart. P. R. S. Bates
XXXII. Experiments to inveftigate the Variation of Local Heat.
By James Six, E/g.; communicated by the Rev. Francis
Wollafton, LL.B. F. R.S. poze
XXXII. Account of fome Obfervations tending to inveftigate the
Confiruction of the Heavens. By William Herfchel, Ef.
«PRLS. Cp. 437.
XXXIV... An Account of a new Species of the Bark-Tree, found
in the Ifand of St. Lucia. By Mr. George Davidfon; com--
municated by Donald Monro, M. D. Phyfician to the Army,
eR. S. pe age:
EXXV. An Account of an Obfervation of the Meteor of Augutt
18, 1783, made on Hewit Common zear York. In a Letter
Jrom Nathaniel Pigott, E/g. F. R.S. to the Reverend Nevil-
Matkelyne, D. D. F. R. S..and Aftronomer Royal. p. 457
XXXVI. Odfervations of the Comet of 1783. In a Letter from
| Edward Pigott, E/q. to the Rev. Nevil Mafkelyne, D. D.
FP. R. S. and dftronomer Royal. p. 460
XXXVII. Experiments on mixing Gold with Tin. In a Letter
Jrom Mr. Stanefby Alchorne, rt his Majefty’s Mint, to Peter
Woulfe, Lf. F. R. S* pe 403
4 MXAY IIT.
Vili, Co Ow NYT Ean Pian |
~ XXXVI. Sur un moyen de donner la Direction aux Machines
Aeroftatiques. Par M. Le Comte De Galvez. Communicated
by Sir Jofeph Banks, Bart. P.R.S. | -—p. 469
XXXIX. An extraordinary Cafe of a Dropfy of ihe Ovarium,
with fome Remarks. By Mr. Philip Meadows Martineau,
Surgeon to the Norfolk and Norwich Hopital; communicated
by John Hunter, B/7. F.R. S. p- 471
XL. Methodus inveniendi Lineas Curvas ex proprietatibus Varia-
tionis Curvature. Pars fecunda. Auttore Nicolao Lander-
beck, Mathef. ProfefJ. in Acad. Upfalienfi Adjunéio. Com-
municated by the Rev. Nevil Mafkelyne, D. D. F.R. S.
Afironomer Royal. Pp: 477
fe LO BO wR ALT CALE
BoA AG if okcO N.S.
as paste
“asa On the remarkable Appearances at the Polar Regions of the
Planet Mars, the Inclination of its Axts, the Pofition of its
Poles, and its fpheroidical Figure; with a few Hints relating
to its real Diameter and Aimnofphere. By William Herfchel,
Eff. F.RTS.
Read March 11, 1784.
Ww I have to offer on the fubject of the remarkable
appearances at the polar regions of Mars, as well as
what relates to the inclination of the axis, the pofition of the
poles, andthe fpheroidical figure of that planet, is founded on
a feries of obfervations which I {hall deliver in this paper; and
Vor, LXXIYV. Ii | after
? (way Reid (i)
. ve
234 Mr. Herscuer’s Obfervations
after they have been given in the order they were 2 made, it
will. be eafy to fhew, by a few deductions from them, that my.
theory of this planet is fupported by facts which will fuffi-
ciently authorife the conclufions I have drawn from them. For
the fake of better order and perfpicuity, however, I fhall treat
each fubject apart, and begin with the remarkable appearances
about the polar regions. The obfervations on them were made
with a view to the fituation and inclination of the axis of
Mars; for to determine thefe we cannot conveniently ufe the
{pots on its furface, in the manner which is practifed on the
fun. The quantities to be meafured are fo fmall, and
the obfervations of the center of Mars fo precarious, and
attended with fuch difficulties (fince an error of only a few
feconds would be fatal) that we mutt have recourfe to other
methods.
When I found that the poles of Mars were diftinguifhed with
remarkable luminous {pots*, it occurred to me, that we might
obtain a good theory for fettling the inclination and nodes of
that planet’s axis, by meafures taken of the fituation of thofe
fpots. But, not to proceed upon grounds that wanted confir-
mation, it became neceffary to determine by obfervation, how
far thefe polar fpots might be depended upon as permanent ;
and in what latitude of the globe of Mars they were fituated ;
for, if they fhould either be changeable, or not be at the very
poles, we might be led into great miftakes by overlooking thefe
circumftances. The. following obfervations will affift us in
the inveftigation of thefe preliminary points.
* A bright {pot near the fouthern pole, appearing like a polar zone, has alfo
been obferved by M. MaRazpii See Dr. Smirn’s Optics, § 1094. °
37773
on the Planet Mars. 235
1777, April 17. 7h. 50’. There are two remarkable bright
{pots on Mars. In fig. 1. tab. VI. they are marked
aandb. The line AB exprefles the dire€tion of a
parallel of declination. 10 feet reflector, g inches
aperture, power 211 *.
toh. 20’. They are both quite gone out of the difk.
1779, ‘This year, in all my obfervations on Mars, there is no
mention of any bright fpots, fo that I believe there
were none remarkable enough to attract my atten-
tion. However, as my view was particularly directed
to the phenomena of this planet’s diurnal rotation,
it is poflible I might overlook them.
1781, March 13. 17h. 40’. 20 feet reflector. I faw a very
lucid {pot on the fouthern limb of Mars of a confi-
derable extent. See fig. 2.
June 25. 11h. 36’. 7 feet reflector, power 227. Two
luminous {pots appeared at @ and J, fig. 3.3 @ is
larger than 4. ae :
12h. 15’. With 460. a ee thicker than &, but & is
rather pence
¥2. i. 2 5 anis arawe inte nee: ae b eae thinner.
June.27. ths 20’. Phe two lucid fpots are on Mars.
Pune 25. Tins They. are both vifible ; a, fig. 4. is
much thicker than 4. 3
coh, 55. lines joining a and b hese not go through
the center.
June 30. toh. 48’. The {pot . ais vifible. fig. Ge
11h. 35’. Both fpots are to be feen.
* Phil, Tranf, vol. LXXI. Pe 127. and fig 176,
liz oe gos
256 _ Mr, Herscuen’s Objervations :
1781, July 3. 19h. 54’. a feems to be va than I have
feen 1 it, fig. 6. . .
r1h. 24’. 6 is not yet vifible, fis. a
"Ez h. 36’. T perceive part of 4, fig. 8.
July 4. 12h. 9. @ is very full; 6 extremely thin, and
barely vifible.
12h. 18’, a and 3 are not quite oppofite each other.
12h. 49’. 4 is increafed.
Vay £4. 0.0. Sa. 4 15 vaibles fac.o.
rth, 35’. dinvifible.
‘72h. 12’. } not to be feen. |
July 16. 11h. 9’. The bright {pot a is very large.
Jlyg em. Ak ye ee No other, bright fpot but ae
July 19. 13h. 31’. 2 vilible: |
July 20. 10h. 3”. Tfuppofe the bright ae a on Mars
is, very nearly, the fouth pole; which, therefore
mutt lie in fight. “There is no fecond bright {pot 6
~ vifible to night. ; -
10h. 56’ 6 not vifible; the night very fine.
July 22. 11h, 14’. At @ and 4, fig. ro. are bright
fpots; a is larger than 4. Moft probably the fouth
pole is in view, and the north pole juft hid from our
fight. If the {pots are polar, or nearly fo, then @
muft, on a fuppofition of the fouth pole’s being in
view, appear larger than 4; and if d extend a little
more from the north pole one way than another, it
mutft be fubjeét to fome change in its appearance from
the revolution of Mars on its axis.
July 30 gh. 43’. Both {pots vifible. +
Auguft 8. 10h. 4’. Only a vifible, fig. II.
Auguft'17. 9h. 21’, Only a in fight. :
3781,
on the Planet Mars. 237
1781 ; Auguft 23. 8h. 44’. a as ufual, and part of 4 vifible,
fig. 12)
Be ot. 4. The white {pot a is very eect Hy
sce May 29. Mars has afingular appearance. Ata, fig. 13..
is the polar fpot, whichis bright, and feems to pro-
ject above the difk es its {plendour, caufing a break.
atc.
July 4. 2 is very bright.
July 23. t4h. 45’. a isvery lucid.
Auguft 16. I faw the bright fpot with the 20 feet
refleCtor as ufual.. »
Aug. 26. The lucid {pot'on Mars is its fouth pole, for
it remains in the fame place, while the dark equato-
rial {pots perform their conftant ee it is:
nearly circular.
Aug. 29. The fouth pa {pot is in the Casi fituation..
septog) Asufualy: 9.
_ Sept. 22. The fouth’ polar {pot is of a circular fhape,,
and very brilliant and white. I hada beautiful and
Vv diftinét.'view: of it when it was about the meridian,.
and meafured its little diameter in the equatorial di-
fi | re€tion of Mars. )With a power. of 932 it gave -
“ qr’, and I faw it very diftinGly.» The outward
edge of the fpot came juft up to the upper limb; a.
favourable hazinefs, taking off every troublefome
ray, gave me objects in general exceedingly well de-
fined, efpecially Mars.
Teas. 24, 6h. 55’.. Vheypolar e ay, fe 14. as ufual..
Sept. 24. The fame.
1.78 3,,
238 Mr. Heascuer’s Od/ervations
1783, Sept. 25. 12h. 30’. The bright fouth polar fpot a, fig,
15. feems to be fixed in its place, and:goes nearly up
to the margin of the difk; itis perfectly round.
i2h. 55’. The track of the equatorial {pots is incurs
vated, being convex towards the north, fee e, q, fig.
23.: this confirms the white fpot’s being at the fouth
pole. With long attention I can perceive the edge
of the difk of Mars beyond the fpot, extending about
2 diameter of the fpot.
Sept. 26. 12h. 10% The {pot 2 isin a line with the
center and the end of the hook, fig. 16.
‘Sept. 27, 28, 29. The fpot as ufual.
Sept. 30. toh. 30’. The polar fpot as in fig. 17.
‘Od. 1. gh. 55’. Iam inclined to think, that the white
{pot has fome little revolution, and therefore is not
with its center exactly at the pole of Mars; it is
rather probable, that the real pole, though within
the ipot, may lie mear the circumference of it, or
one-third of its diameter from one-of the fides. A
few days more will fhew it, as I thrall now fix my
eetioalay attention upon it.
toh. r7’. The bright {pot is cebtaiabs not Pifo far upon
the difk as it ufed to be formerly,; and, is either
reduced or has a fmall motion ; which of the two
is'the cafe will be feen in a few hours.
23h. 3. The bright {pot has a little motions for it is
now come farther into the difk.
I concluded now, in general, that none of the bnght fpots
on Mars were exactly at the poles, though they could certainly
not be far from them: for what has been juft related of the
4 ft,
on the Planet Mars. © 239
ft, 2d, and 3d of Oétober 1783, fhews plainly, that the
appearance of the fouthern {pot @ was a little affected by the
diurnal motion of the planet; and the obfervations of the 3d
and 4th of July 1781, fhew alfo that the {pot d could not be
exaQily at the north pole; and that, perhaps, the vifible
branch of the latter extended pretty far towards the: equator.
However, the fouth polar fpot of the year 1783, being very
{mall and nearly round, afforded a good opportunity for deter-
mining its polar diftance, by noting the different angles of
pofition it affumed while Mars revolved on its axis; to this end
many obfervations were taken at different hours of the fame
night, which will be found among the meafures of the angles
of pofition in the next divifion of my fubject. And fince the
different degrees of brilliancy, as well as the proportional ap-
parent magnitude of the {pot, would alfo contribute to the in-
veftigation of this point, I continued my remarks on thofe par-
ticulars, as follows.
1783, O&. 2. 7h. 59’. The bright fpot near the fouth pole is
about half vifible.
O&. 4. 8h. 0%. The polar fpot feems to project above:
the difk as formerly, and is very fmall..
~~ OG. 5. 11h. 13’.. Fhe fpot is very. fmall, and feems
aGtually to bein the circumference.
“11h. 30’. The fpot is fmall, and feems to be with its
fartheft fide in the circumference of the. difk ; or it-
may, perhaps, be partly beyond it, and therefore:
not all in fight.
Fea 7 Ge the {pot much clearer ati I did ‘before.
13h. 15’. The white fpot is more in fight, and of its
_-ufual fize, but does not. feem much to change i its po-.
e fition 3.
Mr, Hraseuen’s Obfervasions
‘fition s however, what change there is thews that it
has been beyond the pole, as it appears to have been
direét while the equatorial {pots were retrograde, q
4783, O&. 9. 11h. 48’. The white polar {pot increafes in
fize, At toh. 35’. it was as in fig. 18, but is now
larger, and coming round towards that part of its
orbit which is neareft to us. See fig. 24,
O&. 10. 6h. 20’. I fee no white polar fpot; but the
planet is too low for any obfervation to be depended
on. |
6h. 55’. The white fpot begins to be vifible; at leaft I fee
it now, the planet being higher than before, fig. 19.
gh. 55’. With 460, the white {pot is confiderably in-
creafed, and fhews a circular form, fig. 20.
Od. 11. 7h. 46’. The bright {pot is very vifible ; the
evening fine; with 278.
Od. 16. 7h. 7’, The {pot is very luminous.
gh. 55’. It feems rather lengthened; perhaps it may
be arrived at the extreme of its parallel of decli-
nation.
O&.17. 7h. 47’. The white {pot a, fig, 21. 1s very
pee
13h. 7’. It is lefs in appearance than it was in the be-
ginning of the evening.
O&. 23. 6h. 46’. The bright fpot is very large and
luminous; 1 fuppofe it to be in the nearer parts of
its little orbit.
7h. 11’. It is fituated as in fig. 22.
O&. 24. 7h. 1’. The white fpot is very large,
O&. 27. 8h. 45’. It is very large and round.
Nov. 1. 7h. 47’. The fpot is round and bright. .
: 5783,
on a ‘Planet Mars. * a
1783, Nov. 11. The deficiency of light which occafions Mars
to appear gibbous, reaches over the fouth polar {pot
| towards the preceding limb, and hides it.
e Nov. 14. Mars. is gibbous, and the polar {pot is thereby
rendered invifible, |
Nov. 17. 6h.0’. The fouth polar fpot is under the fal~
cated defe& of light.
6h. 30’. I do not know whether there be not a faint
glimpfe of the polar fpot left; the weather is too
bad to determine it. :
I have added fig. 25. (tab. X.) to fhew the conneétion of the
rsth, 17th, 18th, 19th, 20th, a1ft, and 22d figures, which
complete the whole equatorial circle of appearances on Mars,
as they were obferved in immediate fucceffion.. The center of
the circle marked 17 is placed on the circumference of the
inner circle, by making its diftance from the center of the
circle, marked 15, anfwer to the interval of time between the
two obfervations, properly calculated and reduced to fidereal
meafure. The fame has been done with regard to the circles
marked 18, 19, &c. And it will be found, by placing any
one of thefe conneéted circles, fo as to have its contents in a
fimilar fitudtion with the figures in the fingle reprefentation
which bears the fame number, that there is a fufficient refem-
blance between them; but fome allowance muft undoubtedly
be made for the unavoidable diftortions occafioned by this kind
of projection. |
In order to bring thefe obfervations on the bright fpots into
one view, I have placed them at the circumference of three
circles (fee fig. 26, 27, 28. tab. VII. VIL. IX.) divided into de-
grees, reprefenting the parallels of declination in which they
wow. LXXIV; Kk revolved
242. Mr. HErscHE.’s Ob/ervations
revolved about’ the poles of Mars. The divifion of the circles: 4
marked 360 is where a fpot pafles that meridiah of the planet —
which is turned towards theearth, and where, confequently, it —
appears to us in its greateft luftre. The motion of the fpot is ac-
cording to the numbers 30, 60, 92, and fo on to 360. In caleu--
lating the daily places of the {pots I have ufed the fidereal period.
_ of 24h. 39’ 21’’,67 determined in my paper on the rotation of
Mars*; and have alfo made proper allowances for the alterations.
of the geocentric longitudes calculated from the fituations of that:
planet given in the Nautical Almanack ; by which means. the:
fidereal is reduced to a proper fynodical period.
The following three tables contain the refult of the éalcula-
tions, and ferve to explain the arrangement of. the obfervations
in the circles. In the firft column are the times when the ob-
fervations were made. In the fecond, the fidereal places of
the fpot in degrees and minutes. In the third column are the >
geocentric longitudes of Mars: at the time of the obfervations..
In the fourth, the neceflary corrections on account of thefe
different longitudes. In the fifth column are the correéted or:
fynodical places of the fpots; and, according to the numbers.
in that column,. they are marked on the circles, where con--
fequently each {pot is reprefented as it muft have appeared to be -
fituated at the time of obfervation.
* Phil. Tranf.vol. LXXE. p 124.
TABLE
on the Planet Mars. : 243
wm AB Sg
Time of objervation. | Sider. place. Geoc. longit. | Correétion. |Synod. place.
oe
a
PD. +H. °M. DD. iM. S. Dee ee ee. IML
Junez5 11 36 2500) 28 OH 366 °"St
eae to aS! eo: O° 19 fe) G0
2 Ee ge 12. 52° 19 I 13. 51
ait, 20) T1359) 28 °0419 23°) Soha
20 Ur 15 310" 40° |) BAM aio. WG
mee gormro: 8481 iagbe. 560) jor) 57 | 289 59
OA es aes BOOK 2 ahr a 57. 1 301 20
Suly 3 110%" 54 263° 40° 19 MOUNT 282 «0
c zr 24 270° 58 | 9 AON 1 2005, 18
| Sina TO 282° 9 19 40 | 280 29
ig 12° 36°} p88" 29° | 9 4179 286. [48
A ee ON weet 28 4 8 5504) 290 25
4” 52\ 49 282 -4° 19 55), | 200749
15 49 54" ase 7 ciel bieint pena
ane eae 158 42 19 53 | 153 49
Gh" 12*'12 OF” 42°. ig So doe a
1 a ASR a 0 9 | 137.39.
7 TEE ke 134 40 | 9g QO ah Mog.) Teas
1G, AS 3% 140 37 (9 1, a2 30m
20 if (1Opg0 3 88) 25.) Io 14 Pare Ak go
20 10 56 101.19): Iho 15 O54 14
23° FE 74 56,)32°, [ag 40 79. 46
39 Qi 43) 349 40) 150 301 1) 530m BO. |
K k 2 i ly AB LE
244 ’ Mr. Herscuer’s Odfervations.
Te) AjgBiegi lah, ae
Time of obfervation. | Sitter. place.
Geoc. longit. | Correction. Synod, place.
D. HH. M. Dis ML,
June2s it 36 86 51
25°. 255,05 96 20
25, MS gor 1i0 12
—
| | Ds Mace) Bame
fF +1 40 88. 31
‘+1 40 go) Oh
a1, 30. Ee ge
é
| +0 43.4 27 59
| Dox M;
2435.
24°35
24 34.
2A. A ak
23. 28
OCDDDDDTOHDDODONOWNO w
i)
bo
p
O
WO
I
r>))
GM
TABLE
on. the, Planet Mars. | 246
yon wt ee Ti.
Time of obfervation. }. Sider. place. | Geoc. longit. | Correétion. |Synod. place.
, Dpkt: M. D. M. Sen DE EM, Dw Be eg VE 3
Sept.25 ©1713 !30 6iiN30, GOs 54 Wo AR6) Aa: 132 6
O& 1. 10, 17 262 > een Ot 6 Oo id 5Gl OnE
ss) Sonn OFS GA So ys oge a4
SIP ehOo.f 22182 SG 10.4.7) SOO 4) 40 1h eee ies
Beha G6 200-. O Ont ay ear oie (eee 5 2OAN4 Je
BF O° 4G DEY Mae One ay IS qe 5 et AY Sie gry
15. Blyod3 off B3er 2 o 6 55 | +3 45 } 241 8
5 aT 30 7 24r gt Oo 8 65 3 45, 14245. 10
§ ope eg DUO ee a aye OOS 5 aoe Gi GO 8
Go 23s Beeb 207-4 O40 .754 +3 44° 1370-48
52» Ig Heo BO a OPO Gay ar ao i mama Zi.
7-48 fgg: HORNA G's COMM Oey 2 7 Le aw Bo etreTer tame T
F 3155 20i 41 0,6) (22) lias hes Ah 2O4ry 5a:
7 Me tS 8) 227 4. OPO 2h |) aus Ta) 22g oe e
9. 11 7148 209 35 On Gi) 401 biehay a Zon at ero Ay
gO 10 55. P36 42 OF SBT hate 27 gl 2Ove ig
LO SRe5O 140 65 OF Bingo +2 26 142 31
LOL FOS 1S IE 7 Os 430 OnE5 GAA LAE ORS RT oe 64
IO. Pa 203 36 Ol) Sarah mes 2h Os. to
16% Dog gee 49 OT PO he ty teats 73 14
16 icgi 46 81 39 OPM Ore ote at fila 82>. 431
16 4.9 6s BUS 2 Oa a heh ike as eG
7 MEN ete 42 19 OE Pal tt oo TO ne
7 IDS 7 150 II BO OA ie sO ae ©) 7 50% Vs} ST i
22, 96 346 , OO Ero 3 10 ob OO ene)
2A NT ae BF Ot. Owes 2 [Or 8 353 2
From the appearance a i diGipyciuencd of. hs biiehts north
polar {pot in the year 1781, we colle& that the circle of its
motion, reprefented by fig: 26. was at fome confiderable diftance
from the pole. - By a calculation, made according to the: prin-
ciples hereafter explained, its latitude muft have been about 76"
or 77° north ;; for I find that, to the inhabitants:of Mars; the
declination of the fun, June 25. 12h. 15’ of our time, was
about 9° 56’ fouth*; and the fpot muft have been at leaft fo
?
He * See p. 259. and 260,
246 Mr. Herscuen’s Odfervations
far removed from the north pole.as.to fall a few degrees within
the enlightened part of the difk, to become vifible to us.
The fouth pole of Mars could not be many degrees from the ‘1
center of the large bright fouthern {pot ef the year 1781,
whofe courfeis traced um fig. 27 5 though the {pot was of fuch
magnitude as to cover all the polar regions farther than 4
7oth or 65th degree, and in that part which was on the meri
dian July 3, at 10h. 54’, perhapsa little farther... :
In the next. divifion of our fubjeét will be thewn, that thd
inclination and pofition of the axis of Mars are fuch, that the
whole circle, fig. 28. (which will appear to be an about 81° 52"
of fouth latitude on the globe of Mars) was in view all the
‘time the obfervations on the bright fouth polar fpot-of the year
1783, which are marked upon it, were made, but in fo oblique
a fituation as to be projected into a very narrow €Ellipfis. See
fig. 24. where mz isthe little ellipfis in which the fpot @
revolved about the pole. Hence then we may eafily account
for the obferved magnitude and brightnefs of the {pot O&. 23,
24, and 27. when it was expofed to us in its snerjdian fplen-
dour. Its fituations O&. 16. and 17..0n one extreme of the
parallel, as well as thofe of O&. 5. and Nov. 4. on the other,
gave us alfo a bright view of it: and, when we pafs over to
that half of the circle which lies: beyond ‘the potes:the much
greater obliquity into which the fpot muft there be projeted
will perfedtly account for its being {maller at 13h. 7 of OG
7. than lat 7 +h, 47’ of the fame evening. It will alfo expla
its {mallnefs O&.4. and its increafe O&. 9. We-thall have
occafion hereafter to recur to the fame figure, fo that I takeno
notice at. prefent of the ee of pofition — are re marked |
upon it. LX
2 : Of —
4
on the Planet Mars.. — ase
Of ihe direction or nodes .of the.axis of Mars, its inclination to-
the ecliptic, and the angle of that planet’s equator with is own
orbit. . |
From the foregoing article we may gather, that the bright«
polar {pots on Mars are the moft convenient objects for deter-
mining the fituation of the axis of this planet; I fhall there--
fore colle@,.in oneview, all the meafures I have taken. of thefe -
{pots for that purpofe. Before I conftruéted a micrometer: for.
taking the angle of pofition, I ufed to draw a_line through the
figure delineated of Mars to reprefent the parallel of declina--
tion.;.in a. few of my firft obfervations, therefore,.I can only -
take the fituation of the polar {pots from fuch drawings, and -
of confequence no great accuracy in the angles, as tothe exac-
number.of degrees, can be expected.
1777, Aprilr7. 7h. 50’. A line drawn. through the middle of»
the two bright polar fpots @ and 4, fig. 1. makes an:
angle of about 63°, with a parallel of declination:
AB; the fouthern {pot preceding andthe northern.
following. oe
My reafon for chufing aine drawn through both the {pots .
rather than through one of ‘them and the center is, firft, that.
they were not fituated quite oppofite each other, and therefore, |
unlefs other obfervations: had pointed out which was moft .
polar, I fhould evidently run the greater rifk in fixing on-
one of them in preference tothe other. Inthe next place, we -
find by the fecond obfervation, page 235. that in two hours and *
a half both {pots were intirely-gone oyt of the difk. This;
Els 4: plainly
oA8 Mr. Hersowey’s Obfervations-
plainly denotes, that they. were both in the fame half off
a {phere orthographically. projected, and divided by a -plane-
pafiing through the axis of Mars and the eye, but that neither
of them were polar. Now, 4 line drawn through two points
not far from oppofite each other, both in the fame hemifphere,
and both removed from the poles of it, muft approach more to.
a-parallelifm with the axis, than a line drawn. through either
of them and the center.
1779, May 9. There being: no lisipht {pots ee which to jie
of the pofition of the poles, it is eftimated from a.
well known dark equatorial fpot, with a line drawn.
through the figure to denote a parallel of declina-
tion. By very rough eftimation. it is about: Ae
fouth preceding.
May 11. The fame figure, being drawn again in ano--
ther fituation, and alfo with a line giving a parallel
of declination, points out, by the fame rough efti~
mation, 62° fouth preceding.
. 4781, June 25. 11h. 35’. The pofition of the fpots @ and 4,
fig. 3. with regard to a parallel of declination, mea-
fured with a micrometer 74° 32’. The fpot @ was.
fouth preceding, and 4 north following.
July 15. toh. 12’. The angle of pofition, of the cen-
ter of the {pot 4, fig. 9. through the center of the
difk, 74°.18/ fouth preceding.
1783, Auguft 16. Pofition of the fpot a, 64° fouth following
the center; but as the planet is not full, the center
becomes dubious, and the meafure therefore may not
be quite accurate, though taken with a 20 feet
refleCtor 3, power 200. bl
Sept.
—
:
on the Planet Mars. ~ B48
£983, Sept. 9. Pofition of the fuppofed fouth pole of Mars
65°12’ fouth following; 7 feet reflector ; power 460.
Sept. 22. Pofition of the fame 52°9' f. following; 460.
Sept. 25. 13h. 30’. Pofition of the fouth polar fpot
56° Us very accurately taken, by bifeGting the
difle of Mars through the bright f{pot, and fuppofing
the planet now near enough the oppofition to induce
no material error. Hitherto I have taken it through
a fuppofed center by endeavouring to allow a little
for what I thought the deficiency in the difks; but
not to-night.
‘OG. 4. 8h. 46’. Pofition of the {pot 51° 21’; Mars
too low and hazy to depend much on the meafure
with fo high a power as 460.
O& 5. The motion of the polar {pot being now w ftrongly
fufpe&ted, or rather already known, I took the fol-
lowing meafures, by way of difcovering its quantity.
11h. 50’. Pofition very exactly taken 50° 6’ f. fol-
bee
14h. 0’. Pofition of the ae 49° 45’
Om 7. 8h. 20’. Pofition 55°12’. In order to fee how
far this meafure might be trufted to, I fet 49° 36’ in
the micrometer, which was evidently too {mall;
next I took 51° 36’, which was alfo too {malls after
this, I took a new meafure, and found 55° 24’,
which appeared to me very exat. 10h. 5’. The
pofition now was 53°. 11h. so’. It meafured 52° £2'.
As there is nothing te diftingith the center, itis ex-
tremely difficult to pleafe one’s felf in bringing the
{pot into a line with it.
Vou. LXXIV, Ll 1783,
250
Mr. Herscusy’s Objfervations
1783, O&. 10. ah. 50’. Pofition of the polar fpot 7°: Rang
with 460, very accurate. Itried a few parts lefs of
the micrometer, but found the meafure too little. I
fee pretty diftinétly, but the air is tremulous.
gh. 55’. Pofition 42° 42’ ;. very difting.
izh. 11’. Pofition 46° 30’ 5. I fee not quite fo well now
as I could with.
14h. 1’. Pofition 44° 12’; but hable to great uncer-
tainty, on account of tremulous air; it becomes.
more difficult to diftinguifh the center when the pla-
net is not perfectly defined. ;
O&. 16. 7h. 7’. Pofition 63° gf. By way of trial I fet
59° 36’, which was too. {mall; alfo 60° 24’ was too-
{mall; again, 61° 24’ wasnot largeenough. Then,
taking a frefh meafure, I found it 62° AB which E
thought right.
gh. 55’. I took apes meafures, and shou the third,.
which was 65° 0’, the beft of all, forI faw the planet
and the {pot remarkably well.
O&. 27. 8h. 45’. Pofition of the polar fpot 59° 3Q’..
I took three other meafures, of which 60? 39’ ap-
peared. to me the beft; it was taken with long atten-
dance and many changes and trials of the wires in.
different pofitions; but the gibbofity of Marsis fuch,
that meafures of the fituation of the fpot,are now no.
longer to be depended on.
Thefe pofitions, I believe, will be fufficient for the purpofe
of fettling the latitude of the polar fpots, and thereby obtain-
mg a correct meafure of the fituation of the real pole. Ihave
referred thofe of the fouth polar {pot of the year 1783 tothe
fame. circle which contains. the obfervations that were made-on.
2 the:
on the Planet Mars: 251
the apparent brightnefs and magnitude of that {pot, that they
may be compared together. (See fig. 28.) The agreement of
the meafures, and the phenomena attending the motion of the
f{pot, are fufficient to point out the meridian of the circle; for
which, from a due confideration of thefe circumftances, I have
fixed on the place where the fpot was O&. 10. 6h. 46’.
Of the angles colleéted in fig. 28. we find 65° o’ the largeft,
and-49° 45’ the {malleft; but, on account of the different
fituation of the earth and Mars, the angle meafured 7’ lefs
O&. 16. than it would have done had the planets remained in
the places they were in O&. 5. when the other meafure was
taken. This being added, we have 65° 7’. The difference be-
tween the two pofitions is 15° 22’. Now, the conftruction of
fig. 28. being admitted, we fee that the angles were nearly
taken at the oppofite extremes of the circle in which the fpot
moved. However, by the 5th column of Tab. III. O&. 5. we
have the fituation of the fpot in the circle with’ refpe&t to the
meridian 281° 44’, and Oct. 16. 114° 6’: therefore the fouth
polar diftance of the center of the {pot is found, by taking half
the fum of the fines of thefe angles to radius, as 7° 41’ (half
of 15° 22’) toa fourth number, which 1s 8° 8’; and the lati-.
tude of the circle, in which the fpot moved about the pole,
therefore is 81° 52’ fouth. ‘This being determined, we have
the following correction for the angles of pofition: radius is
to fine of the angular diftance of the fpot from the meridian
as $° 8’ to the required quantity. This muft be added or fub-
tracted, according as the cafe requires; and thereby we fhall
have the pofition of the true pole from any one of the
meatures. . :
Tfhall now apply the above to determine the fituation of the
exis of Mars. To this end, we fee that, in the firtt place, the
Liz moeafures
252 Mr. Herseuer’s Obfervations —
meafures. muft he corrected for the latitude of the {pot; next, —
they muft be reduced to a heliocentric obfervation, which will
alfo correét them from the difference occafioned by the different
fituation of the planets when they were taken. ‘This. being
done, we may feleé&t two obfervations at a proper diftance; from
which, by trigonometry, we fhall have the, node and inclinas
tion ofi the axis.. When thefe elements are obtained, it, will
be eafy to fee how other obfervations agree with them ; which
will afford the means of correcting or verifying the former
calculations. par oh a
‘Let T, fig. 29. (tab. X) be the earth; & Q gq ¥8 the eclipticas
feen from Ts Pthe point of the heavens towards which the
north pole of the earth is directed ;, M the place of the orbit of
Mars » 7M, where an obfervation of the poles of that planet has
been made, which isto be reduced to its hehocentric meafures
And, firtt, fuppofe it to have been made; at the time of the
oppolition of that planet... Then, the place Mor Q in. the
ecliptic being given, we have the fides Q &, Go Ps whence
the angle Q, of the right-angled triangle P 35 Q, is found,
This being added to, or taken from, the obferved angle of pas
fition of the axis of Mars, according to circumftances. eafily
to be determined, reduces it to.its heliocentric pofition, But
if this obfervation, was not made at the time_of an oppefition, .
but at fome other place m, a fecond correétion is to be applied
in the following manner.
Let the angle g, of the triangle P & g, be found as before, -
and. properly \applied to the pofition of, the axis of Mars now
at m3; then make the angle mSu, at the fun S, equal.to the
angle Sm'T, and » will be the heliocentric place, where the
angle of pofition; when feen from 5, will; appear.to beas it
was found at mw, after the. application. of the, Arlt correétion :
‘ for!
on the Planet Mars... - 453
for Su being parallel to 'T m, and fuppofing the axis of Mars
to preferve its paralielifm while it moves from m to uw, appear-
ances of Mars at »% to an “are at S, mult be the fame as they
are at a to an eye at T. |
Pele following table contains the refult of calculations re-
lating to the angles of fig. 28. In the frft column are the
times when the obferv ations were made. In the fecond, the
angles as they were taken. In the third column are the quan-~
tities of the angles Q, g, calculated from the geocentric lon-
gitudes contained in the third column of the third table. In
the fourth column are.the corrections for the fituation of the
fpot in the circle of latitude obtained from the fines of the
paeles.? m the fifth column of the third table. In the fifth
are the corrections mats s on account of the change of fitua-
days on which the Be. were taken Ae are at
from the third column of this table, and I have aflumed the
4th of October, ‘as being the obfervation neareft the oppofi-
tion, to which Ihave reduced the other meafures. -In the fixth —
column. are the angles of the fecond, corrected by the quan- |
tities contained in the fourth and fifth columns, applied accord-
ing to their figns, . , 7
MPABLE
254 Mr. Herscuer’s Ob/ervations
Te Bene ae
Angles Firft Second ‘Angles
= ae ae taken. eesccatee correction. {correct.} correéted
1), oEEs MESS) sGee os D. aM D. M. M D
Sept25: 23° 20 0 ecO) 27.4 -+23' $G 9 iae ple 54
Oi 4 FBO ee ee Pi ee3 Oe ae 0 56
$7 dhe 504) 59, 8) 2319.) a Boge ae ae
Bag 01 49 48 4 23 10 er 7. Soe of
Bor eae a [$5
7. 8 20 pe ae 22 21 oO. 7 a ae 155
a or 6 |, §3-: 2 |. +23. 25 |. +3 20°) tae
9 o'r 504 527 12 +23 21 | +6 r6] +3 58
Jo 7 SO} 57 12 } +23 22) -4 574.74] 52
10 G55 fae 42, Res 22 pk eae 51
6 7 7l1e3 (2hl423 as] —7 a7] 471155
62 48 : 55
mb 6" $55, 65) G1 23 95 ba 7 88 0 ee
As we have no particular reafon to fele&t one meafure rather
than another, a mean of all the 13 will probably be neareft
the truth; fo that by thefe obfervations, which, as we faid
before, are reduced to the 4th of O&tober, 1783, we find the
pofition of the axis of Mars that day to have been 55° 41’ fouth
following.
From the appearances of the fouth polar fpot in 1781, re~
prefented fig. 27. we may conclude, that its center was nearly
polar. Wefind it continued vifible all the time Mars revolved
on its axis; and, to prefent us generally with a pretty equal
fhare of the luminous appearance, a {pot which covered from
45° to 60° of a great circle on the globe of Mars could not have
any confiderable polar diftance: however, a {mall correétion in
the angle of pofition feems to be neceflary, which fhould be —
taken from the meafure of the 15th of July, becaufe that
branch of the {pot which probably extended fartheft towards
the
on the Planet Mars. 266
#he equator, was then in the following quadrant. The mea-
fure of both the {pots on June the 25th, 1781, is {till more
to be depended on, as giving us very nearly the pofition of the
true pole; for it appears evident from the phaznomena of the
bright north-polar {pot in fig. 26. that that fpot was in the
meridian when the meafure was taken, while the fouthern {pot
was in the preceding quadrant near its greateft limit. Now,
fince an angle at the circumference of a circle is but half the
angle at the center, when the arches which fubtend thefe
angles are equal, the correction neceflary to be applied to the
meafure taken through the two fpots will be but one half of
the correction which would have been requifite had it been
taken through the center; therefore, in order to reduce this
to the condition of the former, we may fuppofe it to have been.
taken through the center of Mars when the {pot was only 30, or
1 5odegrees from the meridian. It is alfo neceffary to add 1°54’ to.
the angle of July 15, which it would have meafured more had
the planets remained where they were June 25. ‘This done,.
we may have the polar diftance of the center of the fpot as
before. Half the fum of the.fines (of 231° 38’ and 150°) to
tadius, as 50’ (half the difference between 74° 32’ and 76° 12’)
to a fourth number, which is 1° 18’.
I fhould obferve here, that the meafures of the angle of pofi-
tion would be too large before the {pot came to the meridian,
and too {mall afterwards, the axis of Mars being fouth pre~
ceding; whereas, in fig. 28. they would be too {mall before,,
and too large after, the meridian paflage, the pole being fouth:
following.
‘Thefe two obfervations arranged as thofe in the fourth table,,
and reduced to the time. of the 25th of June, will ftand as.
follows.
| TABLE
25 Fe Henscmet' s Ofrvations
aR? BPE Ey
Firt | Second] ce ae
Angles oy
Angle Qe correction. {correct,
Time of obfervation.
Time o t Hea
veer —SSe.
A hoe) Dah | DM DM
74 32 = LO = are tneae —-O 0 75
47418 8) 20) SR lee 14h eae
ee
D. H. M
June25 #1 36
Ply tg) 40%) 12
Iam to remark, that we have here admitted both meafures’
as equally good; and that, therefore, the refult is a mean of
them both, and fhews the axis of Mars, June 25, 178%, to
have been 75° 11’ fouth preceding.
Our next bufinefs will be to reduce thefe two geocentric ob=
Yervations to a heliocentric meafure. ‘This is to be done, as we
have fhewn before, by a calculation of the angle Q, fig. 29.
The refult of it fhews, that 10° 14’ are to be fubtraéted from
the mean corrected angle of pofition, reduced to June 25, 1781,
and 23° 18’ to be added to the angle which is the corrected
mean of 13 meafures, reduced to O&. 4, 1783. Hence we
learn, that on thofe days and hours, when the heliocentric
places of Mars were gs. 24° 35’, and os. 7° 15’ (which would
happen about July 18, 1781, and Sept. 29, 1783) an ob-
ferver placed in the fun would have feen, on the former,
the axis of Mars inclined to the ecliptic 64° 57’, the north
pole being towards the left; and on the latter, he would’
have feen the fame axis inclined to the ecliptic 78° 59’, the
north pole being then towards the right.
The firft conclufion we may draw from ‘thefe principles is,
that the north pole of Mars muft be direéted towards fome
point of the heavens between gs. 24° 35 and os. 9° ey be=
eaufe the change of the fituation ef the pole from left to right,
which
“on the Planet Mars! | 267
which happened in the tite the planet paffed from one’ place »
to the other, ‘is a plain indication of its having gone through ”
the node of the axis. Next, we may alfo conclude, thatthe .
node mutt be confiderably nearer the latter point of the ecliptic :
than the formet ; for, whatever be the inclindtion of the axis, °
it will be feen under equal’ angles at equal diftances _ the «
node. tee , oes
But, by a trizonometrical procefs of folvinga few triangles,
we foon difcover both the inclination of ‘the’axis, and the plaéé »
where it interfects the ecliptic at reCtangles’ (which, for want
of a better term, I have perhaps improperly called its —_
Accordingly I find, by calculation} that the node is in 172 ay"
of Pifces, the north pole of Mars: being’ directed: towards ‘that
part of the heavens ; : and that the inclination of ‘the axis to.
the ecliptic is 59° 42’. | Pond Oaiy
We fhall now compare the obfervations of an earhier date’
with thefe principles, to’ fee how far they agiee. Some of the»
particulars and calculations relating to them areas follow.’ °
GA A aE ML
1 Times of Obiervation, [Eltimations, | ede. Toueits | Angie Q. | 2d éorred.
Se Ome en ees | ee
D: H. M1 D. SD. Mol De ee |
1779, May 9 ‘12 © Ao 7 22 201414 45) +O oO
~ May ir’a2 0 62 7p 28-. dO labi85 Ripa 20
eee | eee
1777, Apr. 1 SON, “63 | 6 3 34 1423 26
i em So eee eee
‘May the 9th, 1779, as we have feen, the angle Ae ee |
was roughly. eftimated at 42°, and ‘May 11. at 62°. The great
difagreement of thefe coarfe eftimations is undoubtedly owing
to the very different fituation of the dark {pot from which they
eVou. LXXIV,. M m ! - were"
2 58 Mr. Herscne’s Obfervations
were taken; however, fince we do not mean to ufe thefe ob-_
fervations in our calculations, they may fuffice in a general _
way to thew, that the axis of Mars was actually about that
time in fuch a fituation as our principles give it: for, reducing
the two pofitions to the gth of May, that of the 11th, from
an allowance of 26’ for the fituation of the planets, will be-
come 62° 26’; and a mean of the two, 50° 13’ fouth pre-—
ceding ; which, reduced to a heliocentric obfervation, gives.
66° 30’, the north pole lying towards the left. Now, on cal-
culating from the pofition of the node and inclination of the
axis before determined, we find, that the heliocentric angle
was 62° 49’, the north pole pointing towards the left; and a
nearer agreement with thefe principles could hardly be expected
from eftimations fo coarfe. If we go to the year 1777, and
take the pofition of the two bright {pots obferved the 17th of
April, we have 63° fouth preceding; this, reduced to a helio-
centric quantity, gives 86° 26’ of inclination, the north pole
being to the left. By calculating we find, that that pole was
then actually 81° 27’ inclined to the ecliptic, and pointed °
towards the left as feen-from the fun.
The inclination and fituation of the node of the axis of Mars
with refpect to the ecliptic being found may thus be reduced.
to that planet’s ownorbit. Let EC, fig. 30. (tab. X.) be a part
of the ecliptic; OM part of the orbit of Mars; PEO a line
drawn from P, the celeftial pole of Mars, through E, that
point which has been determined to be the place of the node of
the axis of Mars in the ecliptic, and continued to O where it in=
terfects the orbit of Mars. Now, if according to Mr. pe La
Lanpe we put the node of the orbit of Mars for 1783, im:
1s.17° §8’, we have from the place of the node of the axis
(that is, 11s. 17° 47’) to the place of the node of the orbit, -
3 an
on the Planet Mars. — 259
an arch EN of 60° 11’; in the triangle NEO, right-angled
at E, there is alfo given the angle ENO, according to the fame
author, 1° 51’, which is the inclination of the orbit of Mars
to the ecliptic. Hence we find the angle EON 89° 5’, and
fide ON 60° 12’. Again, when Mars is in the node of its
orbit N, we have, by calculation from our principles, the angle
PNE = 63° 7’, to which, adding the angle ENO=1° 51’, we
have PNO = 64° 58’; from which two angles PON and PNO
with the diftance ON, we obtain the inclination of the axis of
Mars, and place of its node with refpect to that planet’s own
orbit ; the inclination being 61° 18’, and the place of the node
of the axis 58° 31’ preceding the interfection of the ecliptic
with the orbit of Mars, or in our 19° 28’ of Pifces.
. Being thus acquainted with what the inhabitants of Mars
will call the obliquity of their ecliptic, and the fituation of
their equinoctial and folftitial points, we are furnithed with the
means of calculating the feafons on Mars; and may account,
in a manner which I think highly probable, for the remarkable
appearances about its polar regions.
But firft it may not be improper to give an inftance how te
refolve any query concerning the martial feafons.. Thus, let it
be required to compute the declination of the Sun on Mars,
June 25, 1781, at midnight of our time. If vy ¥ m9, &c. fig. 31.
(tab. X.) reprefent the ecliptic of Mars, and + a+ vg the eclip-
tic of our planet, Aa, 4B, the mutual interfection of the mar-
tial and terreftrial ecliptics, then there is given the heliocentric
longitude of Mars, vrm=9s. 10° 30’; then taking away fix
figns, and = 4, or va=1s. 17° 58’, there remains 6m =
1s. 22° 32’, From this arch, with the given inclination, 1° 51’,
of the orbits to each other, we have cofine of inclination to
radius, as tangent of dm to tangent of BM=1s, 22° 33’. And
M m 2 taking
$i. si Mr. HeRsenEr’s Objervations
taking ee By =1s.'1° 29’, which ‘is'the.complement to yw B_
(ors A, ecyaiig thewn to be'1s. 28° 31’) there will remain
eM= 70s. 204, the place. of Mars in its own orbit®; that is,
on the time abovementioned, the fun’s‘longitude on Nee il
be 6s. 21° 4’, andthe obliquity of the martial ecliptic 28°. 42!
being alfo given, we tht by the ufual method, ne fun's
declination 9° 56’ fouth.” i
The analogy between Mars and'the Bird arial by fut
the greateft in the whole‘ folar fyftem. « Their diurnal motion is
nearly the fame; the obliquity of their re{pective’ecliptics, on
which the feafons depend, not very different; of all the :fupe-
rior planets the diftance of Mars from the fun is by far the
neareft alike to that of the earth: nor will the length of the
martial year appear very different from that which we enjoy,
when compared to the furprifing duration of the years of Jus
piter, Saturn, and the Georgium Sidus. If, then; we find
that the globe we inhabit has its polar regions frozen and co-
vered with mountains of ice and fnow, that only partly melt
when alternately expofed to the fur, I may well be permitted:
to furmife that the fame caufes may probably have the fame
effect on the globe of Mars; that the bright polar {pots are
owing to the vivid réfle@tion of: light from frozen regions)
and that the reduction of thefe {pots is: to be afcribed to:their
being expofed’td the fun. In the year 1781, the fouth‘polar
{pot was extremely large, which we ‘might well expect, fince:
that ‘pole had ‘but: lately been involved in a whole twelve-:
month’s darknefs and abfence of the fun; but in 1783 I found!
it confi bape {maller than before, and it decreafed coneaaella :
r
* If no MELE great yee Bae gat we may add 3s, 10° 34’ to any giver i
place of our ecliptic, which will at once reduée it to what it fhould be called on ,
the orbit pF ‘Mars, and will always be true to within a minute.
| from
on the Planet. Mars. 261 i
from the. 20th of May till about the middle of September,
when it feemed to be at a ftand. During this laft period the
fouth pole had already been above eight months enjoying the
benefit of fummer, and full continued to. receive the fun-beams ;
though, towards the latter end,.in fuch an oblique direction as
to be but little benefited by thems On the other hand, in
the year 1781, the north polar {pot,, which had then been its -
twelve-month in the fun-fhine, and was. but lately. returning |
to darknefs,~ appeared {mall, though undoubtedly increafing
in fize. . Its not being vifible in. the year 178: 3 18:00: objection
to thefe: phenomena, being owing to the pofition of the axis,
by which it was removed out of fight ;.moft probably, in the
next oppofition.we fhall fee it renewed, and of confiderable ex-
‘tent and brightnefs; as, by the pofition, of the axis of Mee 2
the fun’s fouthern declination will:then be no more than 6° 257."
on that planet. .
Of the [pberoidical figure of Mars.:.
_ That a planetary globe, fuch as Mars, turning ON an aXisy..
Bould be of a f{pheroidical form, will. eel find. admittance, .
When two familiar inftances in Jupiter and the earth, as well
as the known laws of gravitation and centrifugal force of ro-
tatory bodies, lead the way to the reception-:of: {uch doctrines.
So far from creating difficulties or doubts, it will rather appear -
fingular, that the fpheroidical form of this planet,: which the -
following obfervations will. eftablifh, has not already been no- -
ticed by former aftronomers ;. and yet; reflecting on the general -
appearances of Mars, we foon find that opportunities for making
obfervations on, its. real form cannot be very. frequent: for,
when it is near enough to view it to an advantage, we fee it
6. generally
ws
262 Mr. Herscuer’s Odfervations
generally gibbous, ‘and its oppofitions are fo fearee, and of 8
fhort a duration, that in more than two years time we have
not above three or four weeks for fuch obfervations. Befides,
aftronomers being already ufed to fee this planet generally
diftorted, the {pheroidical form might eafily be overlooked.
Objervations relating to the polar flattening of Mars.
1783, Sept 25. gh. 50’. I can plainly fee that the equatorial
diameter of Mars is longer than the polar. Meafure
of the equatorial diameter 21” §3’”; of the polar
diameter 21” 15’ full meafure, that 1s, certainly not
too fmall. The wires were fet as outward tangents
to the difk, and the zero, as well as the meafures,
were taken by the light of Mars.
Sept. 28. 14h. 25’. I fhewed the difference ‘of/the
polar and equatorial diameters of Mars to Mr. Wi1-
son, Affiftant Profeflor of Aftronomy at Glafgow.
He faw it perfectly well, fo as to be entirely con-
vinced it was not owing to any defect or diftortion
occafioned by the eye lens; and, becaufe I withed
him to be fatisfied of the reality of the appearance,
while he was obferving, I reminded him of feveral
well known precautions; fuch as caufing the planet
to pafs dire&tly through the center of the field of
view, and judging of its figure at the time when it
was mott diftinct and beft defined, and fo forth,
Sept. 29. I fhewed the difference of the polar and equa-
torial diameters of Mars to Dr. BLacpren and Mr.
AuserT. Dr, BLAGDEN not only faw it imme-
diately,
on the Planet Mars. 263
diately, but thought the flattening almoft as much
as that of Jupiter. Mr. Avsert alfo faw it very
plainly, fo as to entertain no manner of doubt about
the appearance.
As we cannot take too many opportunities of confirming
_ our own obfervations by the eyes of other obfervers, I efteemed
it a very fortunate circumftance to have the honour of a vifit
from thefe gentlemen at fo particular a time, Mars being this
day within 37 hours of the oppofition, and yefterday when
Mr. Witson faw it, within about two days and a half.
1783, Sept. 30. roh. 52’. The difference'in the diameters of
Mars is very evident and confiderable.
Meafure of the equatorial diameter 22” 9!” with 278.
Second meafure - “5 22/031" full large.
‘Polar diameter very exat 0 =. 25’, 26/7",
O&. 1. roh. 50’. I took meafures of the diameters of Mars
with my 20-feet reflector. The equatorial meafured
103 parts of the micrometer; the polar 93. The
value of the divifions in feconds and thirds not being
well determined, on account of fome late. change in
the focal length of the feveral 20-feet object metals f
ufe, we have only from thefe meafures the propor-
tion of the diameters as 103 to 98.
r3h. 15’. Every circumftance being favourable, I took
the following meafures of the diameters of Mars
with my 7 feet reflector, and a diftinét power of
625.
Equatorial diameter . 22’’ 12’’’ narrow meafure..
22” 46’ rather full.
221 3517" exact,
Polar
aMr. eaecurs’ S Obfrvation |
Odom Ag Me
ae
*Polae’ ‘diameter 21
33!
” very exact.
of fa: Mars pei ais Ligh all the time I merited, with
all-its figures-upon. the difk appearing diftinly ; ; and,
I think, thefe meafures may be depended upon better
than any I have yet taken.
my 78 35> O&. 5. tah.o’. y ease difference of ‘the diameters is very
fenfible:
O&. 7. gh. 43’. The flattening of the - «oles is very
-vifible.
‘13 hy go’. IT turned my Newtonian 7-feet refle@tor one-
quarter round, fo as to bring the place to:look in at to
‘the bottom; -and;-as well as the uneafy pofture
‘would: allow, I faw the flattening of the poles the
fame as when I looked in at the fide; power 460.
‘g4h. 30’. With a 34 feet achromatic telefcope and a;
fingle eye lens, I faw the difference of the polar and
equatorial diameters-very plainly.
“Ok. 9. 8h. 40’. Iturned my refletor go° round, fo as
new to'look'in at the upper end, but faw not the
leaft difference in appearances; for, returning it again
' ‘immediately to its ufual pofition, in both cafes the
equatorial diameter appeared a little longer than the
other; power278, andthe evening fine. ,
I’turned the great f{peculum one quadrant in its cell,
but appearances were not in the leaft altered; the
equatorial diameter {till was a little longer than the
polar one.
‘I tried a very fine new obje&t fpeculum, and found alfo
the equatorial diameter a little longer than the polar
-one.
1783,
1783,
on the Planet Mars. | 265
Ok. 9. 10h. 47's The flattening at the poles very vifible.
O&. 10. gh. 55’. A little of the polar flattening is vi-
fible, fo as to admit of no doubt; power 460, very
difting. | |
rth. 32’. Mars vifibly flattened, but not much; the
achromatic fhews it alfo. |
ith, 42’. The difk of Mars is vifibly {pheroidical.
O&. 11. 7h. 37’. Mars is plainly gibbous, therefore
meafures and eftimations ef the diameters muft for
the future be improper.
11h. 12’. It is rather difficult to fay of what fhape
Mars is now, for itis partly flattened and partly gib-
bous; but the gibbous fide not being quite in the
polar dire€tion of Mars, this produces altogether an.
odd mixture of fhapes: however, upon the whole,
the polar diameter is full rather the {malleit.
11h. 13’. The preceding fide of Mars thews the flat-
tening of the poles, while the followimg is termi-
nated by an eluptical, arch.
O&. 12. 11h. 12’. The flattening upon the shale is
vifible.
O&. 17. 13h. 7’. The effect of gibbofity is {carcely
equal to the flattening; or, upon the whole, the
planet is full rather broader over the equator than
over the poles.
Nov. 1. 7h. 56’. The femi-difk, which 3 is full, is evi-
dently part of an oblate fpheroid ; but, to an eye not.
attentively looking for it, and knowing the fhape and
exact fituation of the poles of Mars, this would
probably not appear.
‘Vor. LXXIV. | Nn ‘i 1783,
266 Mr. Herscner’s ‘Objersiasione
rahe
1703; Nov. 10. gh. 30% The gibbofity of Mars is now fuch, :
that the polar diameter is confiderably longer than the
equatorial; but the deficiency not being exadtly from
pole to pole, makes the difk of a crooked, irregular
figure, and renders precifion 7 in this eftimation impof-
fible; otherwife the phate of Mars would have made
a pretty good micrometer upon the equatorial diame-
ter, and it was with fuch a view I had dire¢ted my
‘attention to this circumftance: appearances, how-
ever, are vifibly in favour of the polar’ diameter’ S
bein — the toi geft.
We find that the quick alterations in the vifible difk of Mars,.
during the time it is in the beft fituation for us to obferve it,
are fuch, that if we were to ufeé many meafures which have
been taken of its diameters, we fhould be obliged to have re-
courfe to a computation of its phafes, in orde? to make proper’
allowance for them. Now, fince thefe changes are in a longi-
tudinal dire€tion, and the poles of Mars are not perpendicular
to the ecliptic, it would bring on a calculation of fmall quan-
tities, which it is always beft not to run into where it cam be
avoided. For this reafon, I fhall at once fettle the proportion
of the equatorial to the polar diameter of this. planet, from the
meafures which were taken on the very day of the oppofition.
I prefer them alfo on another account, which is, that they were —
made in a very fine, clear air, and were repeated with a very
high power, atid with two different inftruments, of whofe
faithful reprefentation of celeftial objects, the many obferva-
tions on very clofe double ftars I have made with them have
given me very evident proofs.
on the Planet Mars: 264
_ As we are at prefent only in queft of the. proportion of: one
diameter to the other, the meafures of the 20-feet reflector,
though not piven in angular quantities, will equally fuffice for
the purpofe.. By them we have the equatorial diameter to the
polar as 1030 98, or as 1355 to 128g. I have turned the
proportion into the latter numbers by way of comparing them
the better with the meafures of the 7-feet refleQor. By. that
inftrument the equator of Mars, Oct. 1. we find, was mea«
fured three tinies; but from the remarks annexed to the dif-
férent refults, I think the third meafure fhould be ufed. In-
deed, on taking the difference of the two firft. which is 34’”,
and dividing by three, we have the quotient, 112/”; then,
allotting two-thirds to the firft, becanfe the remark fays pofi-
tively ‘¢ narrow meafure,”’ it becornes. 22’ 342/’’, and taking
one-third fromthe fecond,. which. is. expreffed doubtfully,
‘rather too, full,’ it becomes 22’ 352’: this refleCtion on
the two firtt meafures gives additional validity to the third,
_ which: is 22/35’, of 1355/”. The polar diameter was meafured.
twice; and asno reafon appears againft either of the obfervations,,
I fhall take the mean of both, which is:21’’ 29’’, ot 1289/3
fo that by thefe meafures the equatorial.diameter of Mars is to
the polar as 1355.to. 1289. A. lefs perfect agreement between.
the proportions of the-diameters arifing, from the meafures of
the 20-feet refle€tor and thofe which we have juft now deduced
from the 4-feet, would have been fafficient for our purpofe, as
we might eafily Have excufed' one or two thoufandths of the
whole quantity ; however, we have no caufe to be. difpleafed
with this coincidence, though it fhould’ in part be owing to
accident, and therefore fhall’ admit the above proportion, and
proceed to a farther examination of it,
Nn2 ts In
268 | Mr. Herscue’s Objervations
In the firft place, it will be neceflary to fee whether: any dork
rection be required on account of the different heliocentric and
geocentric fouth latitude of Mars; which would apparently —
comprefs the polar: diameter a little, by the defeé&t of illumina-
tion on the north. On computation we find, that a differenéée
arifing from that caufe would give the longitudinal diameter'te
the latitudinal as 20000 to 19987; which bemg much lefs
than one thoufandth Cia of the whole, may therefore be
neglected. HG
But next, avery confiderable correction muft be admitted,
when we take into account the pofition of the axis of Mars.
‘The declination of the fun on that planet, at the time the
meafures were taken, was not lefs than 27° fouth; fo that the
poles were not in the circumference of the difk by all that
quantity. On a fuppofition then, that the figure of Mars is
an elliptical {pheroid, we are now to find the real quantity of
the polar diameter from the apparent one. It has been proved,
that, in the ellipfis, the excefles of any diameters above’ the
polar one are as the fquares of the cofines of the latitudes * ;
but the diameter at rectangles to the equator of Mars, which
was expofed to our view in the late oppofition, was not the
polar one, but fuch as muft take place in a latitude of 63°.
Putting therefore m=cofine of 63°, 4= 1355, 6=1289, «=
; b— mm.
the polar axis, we have.1:m*::a@-x:6-—x%. And : —
=
which gives us 1272 nearly, for the polar diameter. The true
proportion, therefore, of the equatorial to the polar diameter
will be as 1355 to 12723; which, reduced to fmaller but lefs
accurate numbers, is 16 to 15 nearly.
* Afir, par M. pE 1A LanpeE, § 2680, ' 3
. I thal]
on the Planet Mars. * . 269
~Juthall now’ alfo mention fome of the other. meafures, ‘but
with'a view only to fhew that they are very confiftent with the
above'determination.” From thofe of the 3oth of September,
for inftance, we colle&t the proportion of the diameters of
Mars as 1340 to. 1286; or, reduced to our. former numbers,
1355 to 1300. Now, fince thefe meafures were taken the
night before the oppofition, they muft'on that: account be as
good as the formers; and, had thofe of the day of oppofition
not been preferred, becaufe they were oftener repeated, and
the fuperior power of the 7, and: great light of the 20-feet
reflector, gave them additional weight, I fhould have taken them
into the account; the very {mall difference, however, cannot
but ftrengthen the refults of the former meafures. | |
From the obfervations of the 25th of September we ae
the proportion of the diameters as'1313 to 12753 and if the
equatorial meafure be increafed in the ratio of 20000: to 19953,
on account of the different heliocentric and geocentric longi+
tude, Mars not being at the full, it will give the ratio of 1316
t0.1275;3 or, conforming to our former numbers, as 1355 to
1 1312. I have not ‘been very ftrict in'the application of the
rrection deduced from the ‘phafes of Mars, fince no other
4 was intended to be made of thefe’numbers than merely to
fhew, that they do not very our differ from thofe we have
pened | before *. | ids
AG | pose, Bite
* Lf more firifinefs be required, let EC, fig. 22. be the ecliptic; PS its-poles;
ps the poles of Mars, and eg its equator. Then, the angle pmcC being found, by
calculation,. we fhall have Cz (radius) to em, (cofine of the difference between
the heliocentric and geocentric longitude) as gv, (line of the angle gmv Or pmC).
toov. Then, fince with Mars C¢ can never be very great, the fimall triangle
qno may be taken for finilar to gum; therefore qi (radius) isto gu (fine of
fm C}
————— Sa
270 Mr. Herscugr’s Obfervations
_ It was obferved, O&. 17, 1783, that the equatorial. diarhe-
ter of Mars was full greater ‘than the polar, notwithfandir °
the depredation of the defe& of light upon it.’ On calcilating
the phafes, we find, that the longitudinal diameter was, that
day, to the latitudinal one as 19711 to 20000, which therefore
could not be an equal balance to oppofe the {ph Soci fone
fo as to render it invifible. ‘ Loada
But, Nov. 10, the proportion | of the joneluiling Seueth
to the Jatitudinal one, from a ‘computation .of the phafe of
Mars, mui{t have been as 18762 to 20000 ; and accordingly it
was by obfervation found to be more than. fufficient to take off
all appearance; of the polar flattening, ne leave a vilible excels
in the axis above the equator. ’ *
To obviate any doubts concerning a fallacy that might arife
from the conyexity of the eye-glafs, or irregular fhape of the
{mall {peculum, I need only refer, for the latter, to the expe=
riments of the 7th and gth of Oober, 1783.: for thould the
fhort diameter of my {mall: plane fpeculum have oceafioned, a
comprefling of the polar diameter off Mars when, expofed: to ity,
half a turn of the telefcope muft bring the other diameter of
that f{peculum into the fame fituation, and a contrary effect
would have followed.; With regard to the former, not only,
the experiments made with the achromatic, but principally the
obfervation with the 20-feet reflector, where Lufed a com-
pound eye-piece magnifying only about 300 times, will fuffi-
ciently exculpate the eye-glafles. It is alfo well known, that
in a fingle Jens the diftortion of the images, if any fuch there
ashige Soe
jp en
5 4)
Wi,
ays ,
pmC) as go (=qu~—vo) to qn 3 which is the required correction or adhe
of the equatorial diameter eg of Mars.
Or, pees mCi and vgm=cofine of the angle Pmp; it will be
quam. Cy
3 > “fhouid
on ibe Planet Mars. 27%
fhould be, will equally ’ afeat the wires of the micrometer,
and give a true meafure notwithftanding ; and the compound
eye-piece I ufed with the 20-feet reflector had likewife the fame
advatitase, for it is conftruéted on the plan lately propofed by
Mr. Ramsbden in the Philofophical Tranfactions*, which he
was fo obliging a8 to cormunicate to. me about a twelve-month
aso, and which I page eg adapted to my large micro-
meters. | a
On the fubject of the figure of Mars I ought to Jebbait
alfo, that perhaps the meafures which were taken of its dia-
meters during ‘the laft oppofition will enable us to afcer-
tain its real fize with greater accuracy than has been done
before. The micrometer which can diftinguifh with precifion
_between the equatorial and polar diameters of this fmall pla-
net, will certainly be adinitted as an evidence of confiderable
confequence; and fince the refult of thefe ‘tmeafures i is pretty
different from what former obfervations give fis; I fheuld not
‘omit mentioning tt:
We have feen that the equatorial diameter, on the day of
the oppofition, meafured 22/7 35’”. The diftance of Mars
from the carth at that time was . 404.57; the mean fees of
the earth from the fun being i; therefore, 227"35" teduced
to the fame diftance will be no more than 9” 8’”.
I fhall conclude this fubje@ with a confideration relating to:
the atmofphere of Mars. Dr. Smirx + reports an obfervation
ef Cassini’s, where “a ftar in the water of Aquarius, at the
‘* diftance of fix minutes from the difk of Mars, became fo
“« faint before its occultation, that it could not be feen by the
“‘ naked eye, nor with a 3-fect telefcope” It is not mene
— * Vol. LXXIIL p. ote
+ Optics, § 1096.
tioned
1 ate bi Mr. Hursenen’s Odfervations
‘tioned what was the magnitude of the’ flar; but, from the.
circumftance of its becoming invifible to the naked eye, We
may conclude, that it muft have been of the fixth or feventh,
magnitude at leaft. The refult of this obfervation would in-
dicate an atmofphere of fuch an extraordinary extent, fince at -
the diftance of 36 femi-diameters- of the planet it fhould full
be denfe enough to render fo confiderable a ftar invifible,
that it will certainly not be amifs to give an obfervation or.
twvo which feem of a very different import. :
1783, O& 26. There are two {mall fixed ftars. preceding Mars,
of different fizes; with 460 they appear. both dufky
., red, and are pretty unequal; with 278 they appear
confiderably unequal. The diftance th Mars of
the neareft, which is alfo the largeft, with 227 mea-
fured 3’ 26” 20”. Some time after, the fame
evening, the diftance was 3’ 8’ 55’’’, Mars being
retrograde. I faw them both very diftinélly. I
viewed the two ftars with a new 20-feet refleCtor of
1.8,7 inches aperture, and found them, as I expected,
very bright.
" O&. 27. I fee the two {mall ftars again. The fmall,
one is not quite fo bright in proportion to the large
one as it was laft night, being a good deal nearer to
‘Mars, which is now on the fide of the fmall ftar;.
but when I draw the planet afide, or out of view, 1
fee it then as well as I did laft night, The cbaues
of the {mall far meafured 2’ 56” 25’” *.
* The meafures were accurate enough for the purpofe, though not otherwife
to. be depended on nearer than, perhaps, fix or eight feconds,
4 : The
Philos. Trans. Vol L XXIV. Tab. VI 7.272.
Philo.
Pia
het
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Lh Via Trains Vol LXXIV.
“LO:
772 ves thle
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July 1240
July 3 iets
= oo f. 2 5
rack wf Lhe Crught noth polar spoton a Mek
2¢ ¢Z )
an func Ta) “ily Ghd
£
Philos Trans. Vol EL. XXIV, Tab. VILL p.272.
OFl e Wa LD,
Philos Trans Vol XXIV, Vab Vill p27
& y
& =
5 =
= te
OLD APU.
‘ oT oook of he bright woul frotar spol on : Yens,
“wM fu ue Ss July YEA.
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Lhilos, Trans, Vol, LXXIV Sab. IX p.272.
a al
1? e Marea:
. Vhilos, Trans, Vil. L XXIV Va, IX, p.272.
‘as : 2
Oct.1.10 17
Oct.5.13 15
ee yim , 2 , ;
Oak a, lhe brig hl Jute fear frat Ci + Wer;
mn Ce fuber 1708 é
a
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os
Phitos Trans. Vol. LE XXIV. Tab. X.p.272.
Eee
By 20). a
: - als
> . — iy
5 .. git aah < =
ae a 4 "
~ ’ y
. . * « oe
- . - -
on the Planet Mars. — 273
The largeft of the two ftars on which the above obferva-
tions were made cannot exceed the twelfth, and the finalleft the
thirteeenth or fourteenth magnitude; and I have no reafon to
fuppofe that they were any otherwife affected by the approach
of Mars, than what the brightnefs of its fuperior light may
account for. From other phenomena it appears, however,
that this planet is not without a confiderable atmofphere ;
for, befides the permanent {pots on its furface, I have often
noticed occafional changes of partial bright belts, as in fig.. 1
and 14.3 and alfo once a darkifh one, ina pretty high lati-
tude, as in fig. 18. And thefe alterations we can hardly
afcribe to any other caufe than the variable difpofition of clouds
and vapours floating in the atmofphere of that planet.
Refult of the contents of this paper.
The axis of Mars is inclined to the ecliptic 59° 42°.
The node of the axis is in 17° 47’ of Pifces,
The obliquity of the ecliptic on the globe of Mars is 28° 42’.
The point Aries on the martial ecliptic anfwers to our 19° 28
of Sagittarius.
The figure of Mars is that of an pale {pheroid, whofe equa-
_ torial diameter is to the polar one as 1355 to 1272, or as
16 to 15 nearly.
The equatorial diameter of Mars, reduced to the mean diftance
of the earth from the fun, is 9/” 8”.
And that planet has a confiderable but moderate atmofphere,
fo that its inhabitants probably enjoy a fituation in a
refpects fimilar to ours.
© Datchet, Dec. 1, 1783.0 sy HERSCHEL.
Vii. LXXIV. Oo
ae
/
XX. A Defcription of ibe Teeth of the Anarrhichas Lupus
‘Linnxi, and of thofe of the Cheetodon nigricans of the fame
Luthor; to which 1s added, an Attempt to prove that the
Teeth of cartilaginous Fifbes are perpetually'renewed. By Mr..
William Andre, Surgeon; communicated by Sir Joteph Banks,
Bart. P. R.-S.
Read March 18, 1584,
HE amazing variety there is in the external form of
fifhes muft be obvious to a‘:common obferver; and who-
ever examines will be convinced, that the fame variety pre-
vails in their internal flrugture. No parts, perhaps, afford’a
more convincing proof of the laft affertion than the teeth of
fifhes. ‘To adduce a few inftances, let us only recolleé the
tuberculated teeth in the ‘thorn-back; the triangular ferrated
teeth in the fhark ; the flender flexible teeth in the ch@todontes,
or angel-fithes. There is not only a difference of their form,
but alfo in the fubftances of which they are compofed; fome
being of afoft horny nature; others made up of bone; others
of that fubftance we call enamel in the teeth of quadrupeds’s
and fome having the apparent hardnefs and ‘tranfpareney of
cryftal. We may alfo notice their uncommon fituation ; “many
fifhes having teeth not only in their jaws, but on the tongue,
the palate, and about the fauces.
To illuftrate in fome degree this part of natural. hiftory, I
fhall defcribe the teeth of the Anarrbichas Lupus, or Sea-
wolf, and thofe of the Chetodon nigricans, a fpecies of
Angel-
Mr. Anpre’s Defeription of, &e. 275
Angel-fifh. ‘The former have been but imperfectly deferibed,
and never reprefented diftiné from the fith, without which it
is impoffible to have any exact idea of their difpofition, num-
ber, or form, while the true fhape and compofition of the
latter, from their minutenefs, have been entirely overlooked.
I fhall then attempt to prove, that a continual renovation of the
teeth takes place in cartilaginous fithes.
Tut Sea-wotr is a fierce and ravenous fith, as its name
imports, found in the northern parts of the globe, where it |
frequently grows to the length of four feet and upwards.
The jaws of the Wolf-fith are made up of feveral bones, to
each of which a greater or lefs number of teeth are affixed s
but, before I enter upon the defcription of them, I fhall take
notice of the palate (marked A, tab. XI.), that being a kind
of bafis or fupport to the other bones, to which they are all
more or lefs connected. The palate is a thick and firm bone
united above to the bones of the cranium and nofe, and ending
below in a flat oyal furface, on which are incrufted about
twelve or thirteen ftrong, blunt, and rather flat teeth of the
molar or grinder kind. ‘The external edges of the teeth are ©
the moft prominent; by which means a hollow is formed in the
middle of the Palate. :
The upper jaw is compofed of three bones, two of which
(BB) are placed laterally, forming the fides of the upper jaw,
and the third (C) anteriorly, making the fore-part of the jaw.
The third bone may be divided through its middle into two
portions ; but fince it has the appearance of one bone only,
the connection being very firm, I fhall defcribe it agreeably to
that appearance, to prevent needlefs divifions. 3
The fide bgnes of the upper jaw have nearly the fhape of an
italic f At their pofterior ends may be obferved a {mooth
O02 | a:ti-
i
296 Mr. Anvre’s Defeription of the
articular furface, for their connection with a fimilar furface on
the pofterior extremities of the lower 7 jaw ; and on their ante-
rior ends there are two rows of teeth.. The external row con-
fifts of three or four fharp or conical teeth; and the internal
sow of four or five blunt and rather flat ones. Thefe bones are
connected to the palate and bones of the nofe by loofe. but
{trong ligaments. 7
The third bone of the upper jaw, which may be called bg
anterior or nafal portion, ‘is of a triangular form, conneéted
above to the bones of the nofe, and ending below in a flat fur-
face, thick-{et with fharp conical teeth. ‘The external teeth,
about four in number, are lar ge and ftrong, and bend a little
inwards ; but the internal ones are fmall, and nearly ftraight,
of which we may reckon about ten.
This bone is connected above (as I have before obferved) to
the bones of the nofe; between which a complete joint is
formed, of that kind called by anatomifts gimglymus, that is,
where the projecting parts of one bone are received by cor-
refponding cavities in the other. Like other articulations, it’ is»
furnifhed with a capfular ligament, and no doubt an apparatus
for the fecretion of /ynovia. Although a joint exifts between
this bone, and thofe of the nofe, yet no mufcles are provided
for its motion, which depends entirely upon the refiftance made
by thofe hard bodies which the animal takes into its mouth.
The lower jaw (D) confifts of two bones, united at their
fore-parts by a ftrong ligament, which allows of fome motion.
On their anterior extremities are placed fix large and as many
{mall fharp and conical teeth; the large teeth are placed exter-
nally, and their points are bent a little mwards; while the
{mall ones, which ftand within them, are nearly ftraight.
Behind thefe are two or three rows of grinder teeth. The
I external
Teeth of the Anarrhichas Lupus. 277
external teeth ftand nearly upright; but the internal ones are
placed obliquely, inclining towards each other.
The teeth are formed of a hard bony matter, not covered
with enamel as in fome animals; nor is- there an equal diftri-
bution of enamel and bone as. in fome others,. They. are not
fixed in fockets, but are faftened to the jaws in: the fame } man-
ner as the efiphy/es are united to the bodies of the bones i in
young animals. ”
From the foregoing defcription it will appears et the ante-
rior fharp teeth of the Sea-wolf are admirably. calculated for
feizing its prey, while the pofterior grinding teeth ferve to
break down the hard. thells of lobfters, crabs, mufcles, {col-
lops, éc.. which this animal is known to feed upon. The ex- —
ternal teeth on the fides of the upper and lower jaw being
higher than thofe placed within them, a-hollow is formed
above and below, in which the convex fthells of cruftaceous
animals, éc.. are confined during their compreffion between
the jaws, which is effected by the action of {trong mufcles - |
placed on the fides of the head.. The jaws being made up of a
number of. pieces, and.connected by loofe. ligaments, a freedom
of motion is allowed, and the collifion or fhock arifing from
the comminution of hard bodies is fo much the lefs by being —
divided among a number of bones.
Merret informs us *, the /apis bufonites are the flat grinder
teeth of this fifh petrified: But certainly thefe foffils are not -
the production of the Sea-wolf alone, fince they may onginate-
from all thofe fifhes which have flat teeth in their palate or
jaws; a ftructure which the French naturalifts diftinguifh by-
the appellation of palais pave.
* Pinax Rerum Naturalium Britannicarum,
OF:
278 Mr. Anpre’s Defcription of the
f
Or THE CHE TODON NIGRICANS
The individual which furnifhed the following account was
brought from the Weft Indies, and meafured about five inches
in length*. Its teeth (the only parts I mean to defcribe)
were fo fmall as to require the afliftance of a microfcope to
difcover their real fhape. There were fourteen teeth in each
jaw, feven of which from the upper one are reprefented
tab. XII. They confift of a cylindrical body fixed in
the jaw, above which they fpread out into a broad and
rather flat furface, on the edges of which are twelve or thir-
teen denticuli, making an uncommon appearance, and totally
different from the teeth of any other animal, Another fingu-
larity is their being tranfparent, unlefs viewed with a deep
magnifier, when a few opaque lines may be perceived, which
point out the cellular part of the tooth through which the
blood veffeéls ramify, which are deftined for its growth and
nourifhment. They are not all of the fame length. ‘Thofe in
the antefior parts of the jaws are the longeft, from whence
they gradually diminifh in length as they approach the angles
of the mouth. :
From the foregoing defcription of the teeth of the Chetadon
nigricans, this fith feems to be mifplaced in the Syfema Natura
of Linnzus ; fince one generic diftinétion of the Chetodontes
is to have numerous, flender, and flexible teeth; whereas the
teeth of the Chetodon nigricans are few in number, placed in
one row, and of a cryftalline hardnefs, ep
* This fifth is well reprefented in Du Hamex Traité général des Péfches,
tom. III. feconde partie, fection IV. planche xii. under the name of Chirurgien
ex Porte Lancette.
7 Or
Teeth of Cartirginous Fifoes. 279
OF THE TEETH OF CARTILAGINOUS FISHES.
When Sreno examined the teeth of the fhark, he was fur-
prifed to find a great number of them placed on the infide of
each jaw, lying clofe to the bone, and many of them buried
in a loofe fpongy flefh; conciuding that thefe internal teeth
could be of little or no ufe to the animal. Mr. Herissanr *
afterwards fhewed the ufe of thefe internal or pofterior teeth,
by proving, that as the anterior teeth of each row are broken
off, drop out, or wear away, the pofterior ones come forward
to fupply their places +.
But though it be certain that the anterior teeth, when loft,
‘are replaced by the pofterior ones, neither of the above natura-
lifts, or any other that I know of, have attempted to afcertain
how often this circumf{tance happens. Whether the renova~
tion be perpetual during life ; or whether that operation be fuf-
pended after a limited number of teeth have been fupplied.
From a fingular circumftance, which 1 met with fome
time ago, I am inclined to think the former is the fact; or,
that in cartilaginous fifhes, fuch as fharks, rays, &c. there is
a perpetual renovation ‘of the teeth.
Being engaged in diffedting the jaws of a very- large fark I
was furprifed to find a portion of that fharp, bearded /bone
found in'the tail of the fire-flaire, or fting-ray {, driven quite
- * Bowaxe Dittionaire d’Hittoire Naturelle, ‘article Requien,
'{ Itumay-not ‘be improper on this oe¢afion to point out a miftake whiclnfome
@aturalifts have*fallen into, in-allowing a et of mufcles for raifing the numerous
teeth. placed. in the,jaws.of fharks. 1 have frequently diffected the jaws of thofe
animals, and am certain no fuch muicles exift, nor are they indeed at all neceflary.
f Raia Paftinaca Linn x1. “The French naturalifts, on account e the bone
Gn'the tail, “CAN tis Ath Radic’ bajonnette '
“through
286 Mr. Axvre’s Defeription of the
through the lower jaw among the pofterior teeth, and fixed
almoft immoveably. How this happened muft be obvious to
-every one. (See the figure, tab. XII.)
“Before I proceed, it will be neceflary' to obferve, firft, iat
the pofterior teeth of cartilaginous fifhes are always found. ina
foft, membranous ftate, and but imperfectly formed ; notwith-
ftanding this, they have the whitenéfs of teeth from a {mall
quantity of calcareous earth already depofited within their fub-
ftance. Their hardnefs and perfe& form is acquired as they
advance ‘towards the anterior parts of the jaws. Secondly,
that ofthe three ‘angles ‘in each tooth of the fhark, one is
placed towards the ane another towards the left, and the
other, which is in thie middle, and the moft acute angle, is
dire&ed inwardly towards the ‘tongue or fauces. They: are
placed then in fuch a matiner as that the angles of the teeth on
the left-fide in one row, approach’the angles of ‘the teeth on the
right-fide in the next row. Thefe teeth which ftand on a line
from without inwards, I-call a row ; not thofe which are placed
‘nearly in a’ parallel line from one fide of the mouth’ to the
other.
The fharp:bone of the fting-ray was fixed | in ttle lower jaw
between two rows of teeth, and at their pofterior part, where
the firft rudimetits of the future teeth are formed, and it will
be clear to every one, particularly thofe who are converfant in
{uch matters, that this could not have happened without pro-
ducing a great deal of pain, {welling, and diforder in the. part
where it was fixed. It is unneceflary to enumerate the dif>
ferent kinds‘ of ‘nvifchief this might occafion. Let it fuffice to”
‘obfervé, ‘that on account of the fpace taken up by this extra=
neous body, the teeth on each fide of it, for want of room, could
never after be perfetly formed. .The teeth on the left- -fide
A | wanting
t
a
Teeth of Cartilaginoys Fifer. 28y
wanting their angles to the right, and the teeth on the right-
fide being deftitute of. their angles to the left. |
As it is certain, that the anterior teeth were formerly pofte-
rior ones, and as the teeth in each .rew were all deficient in one’
angle, it follows, that they muft have been formed pofterior to
the infertion..of this extraneous body. Again, if we allow
that before the accident the animal was in poffeflion of perfe&
teeth, it follows alfo, that they were coniumed and ee
by imperfect ones. :
There were fix teeth in each row, and fifty-two rows,’
making together about 312 teeth. Now allowing the con-
f{umption to have been equal in all: parts of the jaws, it fol-
lows, that the animal had already confumed 312 teeth, and
was in pofleffion of a like number for future confumption.
The teeth of fharks, rays, &c. may be divided into active
and paffive. The active teeth are the anterior ones of each
row, ftanding with their points upwards. The paflive tecth
are the remaining ones, lying ane upon another, like the tiles
upon a houfe (imbricated), with their points downwards.’ It
appears from the foregoing account, that the anterior or active
teeth had been replaced fix times; and that they might have
been renewed fix times more, making in all twelve times.
From which, I think, we may reafonably conclude, that this
‘does not happen any precife number of times; but that the
renovation is perpetual during the life of the animal.
The longevity of fifhes is a fact pretty well eftablifhed. In
addition to this part of natural knowledge, I have endeavoured
to prove, that a part of the inhabitants of the great deep tre-
tain, in the article of teeth, a perpetual juvenility, being appa-
tently utter ftrangers to edentulous old age.
Vou. LXXLY. P p © XPLA-
pS." geen Mr. Anpre's Dubin stare.
EXPLANATION OF THE reares.
Tab. XL. The jaws of the Wolf-fith. a
A. The palate. s
BB. The fide bones of the upper jaw.
C. The anterior or nafal portion of the fames :
D. The lower jaw.
Tab. XII. The teeth of the Chetodon nigricans magnified.
Tab. XHI. Part of the lower jaw of a large fhark.
AA, Two rows of perfect teeth.
BB. Two rows of imperfect ones.
€. The bone of the fting-ray.
- Philos.Trans.Vol,L XXIV. Vah, Xp, 282.
Philos Trans Vol. L XXIV. Tah. Xp. 282
sh
Sanu
os
i
cs
ieee
, -
Philos. Trans. Vol. L XXIV. Vab,. XML p.282.
LUT
Maps
AT
Mei
Mey
Tn i)
li Heeh
AHEM
,
Philos, Trans. Vol. L XXIV, Tab. XV p.262
CHA TODON nigrican s LINN.
- ; ce
rnp ne aera toms
tS a
1L XXIV, Tab. XU y282.
‘ans.Vo
s. 17
Philo
Philos Trans Vol L XXIV, Tab. Xu p22
{ 283 ]
age Abjiracé of a Regifier af tbe Baremeter, Thermemeior,
and Rein, at Lyndon, in Rutland, 1783.. By Thomas
Barker, Eifq. 3 2 communicated by by Thomas White, Hq. F. R. §<
4
Bead Moreh 18, 478s 4) 2 Me ae
Barometer. Thermometer. { Rain.
In the Houte. Abroad. S¢l- "| South |
Bee oun, Lambeth,
| ae Mean. evens Mean{High {Low.|Mean eae Surrey. |
— =< mee eres | - , — ate i
Inch, E Inch.
es 5805 | 4545
jinches, Inches, |Inches.
29,87 28,38] 29,04
30,12] 28,08 | 29,28 253131 5554
: 30,01 27,88 29,28 1,604] 2,16
|
Ch
|
ee
5 i | 7
30,14] 29,15] 29,70] | 22558 268 }
| 29,82] 29,13] 29,48 | 4,218] 2,84
| 29:85] 28,80} 29,47 31033] 2,82
1] 29289] 2916] 29,55
29,83] 29,17 29549
29,87} 28,47] 29,36
9,663 1,45
1,102] 2.24
1,440} 5953
“| 29:88] 28599] 29,48 0,658] 1,72
a 29:96 | 28,42] 29,45 1,783] 3,01
29,99 | 28,49] 29,29 1,602} 1,10
SS eee
| . Taehes 22,770) 33°74 123,25 §
Pp2 The
be
284 Mr. Banken’s ‘Regifler of the |
The year began with a fhort dry froft, then fhowery, inter-
mixed with froft. The end of January, and near half of Fe-
beuary, ftormy and wet, and after ten days fine and mild; a
fevere feafon for fnow, wet, oe and froft. ~The end of Fe-
‘bruary and beginning of March cut the grafs, corn, and ftock,,
more than‘all the winter before. From March to. to May 27.
was a very dry feafon and fine feed-time; but fo dry at laft the
late {own corn could not come up. The fpring was pleafant 5
but almoft conftant frofty mornings till April, and frequent
afterward, kept things backwards and:though there was fome
fine warm weather the middle of April, yet later in May the
drought aud N.E. winds ftopped the growth of things; and
two fharp frofty nights, May 25. and 26. the rime was fe par- |
ticularly cutting in the meadows, that the young. fhoets.on -
many oak and ath trees in the vallies were entirely killed, while, ft
thofe-on the hills were unhurt; and fome of the tops of the:
trees sees though the bottoms were blafted. 3
May 27. to 30. in a continued three days rain there fell 38
inches, w rich: is, I believe, the moft that has come in one,
continued unceafinge rain fince July 1736, when, in about: che!
{fame time, there came five inches 3 bu the rain this May was. |
not alike in all places, for there was not a quarter fo mudh' ‘ink
Hampthire. This rain was of vaft fervice to bring up the late, |
fown corn, and: make the graff grow well; but this and tome!
other hafty ‘rains afterwards hurt the meadow prafs, by floodingy.
it threé tines. Hot weather fheceedings it was avery’ gro Tn !
time, and ten days together, in the middle of June,, wete ally)
wet. | ase te She | Hiytse ©
Dunne the thowery time an ‘ancofririon: hisinety began!
which | iwas very remarkable all the reft of the. fummer } ‘el,
air was. -all thick both below the clouds and above them, the:
{a 2 a
A OO EN Oe!
s
er
Weather at Lyndon, Rutland. 285
hills looked blue, and at a'diffahee could not be feen: the fun
fhone very red through the haze, and fometimes could not ‘be
feen when near fetting. There was. more or lefs of this haze
almoft conftantly for a month, and very frequently to the end
ef the fummer, and it did not céafe till Michaelmas; and neij-
ther rain nor fair, wind nor calm, eaft nor weft winds, took it
away ; andit was as extenlive as common, for it was the fame
all over Europe, and even-to:the top of the Alps... This haze
was very like: Virci.’s. defcription of the fummer after J. -
C#saAr’s-death, which was probably the fame cafe,
Cum caput obfcurd nitiduim ferrusine exit,
for rufty iron is a very good’ defcription of. the colour the fun
fhone. But by Prurarcu’s account, near the end of C.
Czsar, that fummer was very different from this in other
refpetts for, he fays, the fum gave very little heat,) the-
air;was cloudy and heavy, and the fruits not ripened, which
Was not the cafethis year ;. for this was a dry. haze, the fum-
mer.in general hot and dry,; and’ in fome:countries very much.
frit ORO sh BIO io bee 2k
. Tthink F never knew more: mifchief done by thunder: than.
there was in different places this year, from the beginning of
July, .and. very. feldom more. or hotter: weather;; yet where
they had. not, :thefe thunder-fhowers: they’ fuffered by -being:
burutarp. Here we never) wanted grafs aften May, aid: the:
hay andiharveft were-both: well) Pot) in5. but m Surrey,. Hamp-.
fhirey! and Dorfet, they! were’ very: much: burnt. up, had: little
hays: andias they had!agood'déal of thowery weather im. hares.
veft, their barley duffered twice, from not coming upiim time,,
and again in getting it im. + Asthe rain this yeatwas- chiefly in)
fhowers or fudden. rains, it fell \ ee uncertainly, as appears by.
comparing
286 > Mr. Barxar’s Regifer, &ee
compating what fell here with that in Hampfhire. ‘The latter
part of Auguft and firft half of September was fhawery ; but
in this country not fo much as to hurt the harveft, a great part
of which was in firft. The crop ef grain was in, general
pretty good, but did not yield enough to make up the defeé:
of the laft year’s crop, every body was fo much out of all forts,
as the corn lait year was both fearce aud bad; grain, therefore,
continued dear this year, efpecially barley.
The fummer 1782 had been fo cold and’ wet, that the
flower buds on many trees were very fmall and not perfected,
fo that this {pring there was a great want of bloffoms on the
wall fruit and apples, and exceeding few indeed on ath-trees
and hawthorn. I do not know of any athkeys at all, nor any.
bunches of haws, only a few {cattered fingle ones; but cher-
ries and plumbs bloffomed well, and there was no want of
fruit; plenty of currants, and vaft quantities of goofeberries. |
Auguft 18.a remarkable ball of fire was feen between nine and
ten at night all over England, and even in foreign countries. © It
feemed to move from north to fouth or fouth-eaft. There
was another Oétober 4. but not fo much obferved, and fome
fay another afterward, but little feen; but there. were wigs
northern lights this autumn. i |
The autumn was a very fine ones; calm, fair, and enild, site
rather too dry for the fowing of wheat, which, however, in
general came up well, and what lay dry was brought up very
finely by ten days wet the middle of November; after which
it was dry and fine again, an open mild time, with few frofty
mornings; but a good deal of dark or mifty weather in Decem= _
ber, yet mild till the laft week, when there came a great {now,
very fevere froft, and cutting ftrong wind, which ended the year. _
on
RS
Spsyey ” 7F | he
XXII. On rhe Periods of the Changes of Light in the Star
Algol. Ina Letter from John Goodricke, E/g. to the Rev.
Anthony Shepherd, D. D. FR. S. ii effor %, Aftronomy ak
_ Cambridge.
Read Aprilr, 1784.
ST R,. York, Dec: 8, 178%.
S Iam now able, by collating fome of my late obferva—
. tionsen Algol with thofe I fent you laft May, to deter-:
mine with greater precifion the periodical return of its changes,.
1 wifh to add this as a kind of fupplement to that account.
The method I have here purfued is by taking the intervals
between. accurate obfervations of Algol’s leaft brightnefs or
greateft diminution of light made at long diftances of time
from-each other, and dividing thofe intervals by a certain num-.
ber of revolutions, as will be beft underftood by the table be-
low. The reafon of my chufing: long intervals is, that the
number of revolutions being greater, the errors of obfervatiom
are’ thereby diminifhed:: all error cannot,. however, as yet be:
excluded, but I think the period is now, by the following. alt
cols pe tined within ten or fifteen. feconds.
2 Mean
Be ah oN TC 3b Say
288 Mr. GoopricKe gi the Period of the
‘Mean times of Algol’s
leat Baer ' Nat:
1783 h. altiy. 3S sg gow GL | ieee
ee cae oe i an ipteryal of 99 revolutions, exch of 2 20 49. 14
Q&, 25,6 4
Jes. : oH Ditto 106. Ditto 2 20> ‘ay Bi hy
Jon! 14 9 251 Dito 107 Dito 1) geod
Li : a Ditte ‘gI Ditto 21) 20) 4puare
<a ae ae aoe
Nes a 5 ra Ditto 99 ‘Ditto 2 20 48 el
ve - 2 eg Ditto 84 Ditto = 220 49 M4
Fs $609. I se este oo
i eH A nat Ditto —g2 Onttoet ae a 20 49° 9
fee fF p oteabine of campog Dian 1 bale, iid
a ee ee
Hence the period of Algol’ variation is, on a mean, By 2 08
t)
T could have added feveral more comparifons: ef the ies
kind; but thefe are, I] think, fufficient. It is to be remembered,
that all the obfervations contained 1 in the above table are canny
to mean time. Mf }
It appears to me mow, that the’ duration ‘of the variation is
about eight hours; ‘but, as it is difficult to hit exa€tly the be~
ginning and end of the variation, this may occafion different —
obfervers to differ in this refpect. Before I conclude, I beg
leave to mention a circumftance deferving of notice; which is,
that
Changes of Light in the Star Algol. 289
that FLamsteap has alfo amongft other ftars obferved Algol,
and in two places has marked it of lefs magnitude than at
other times, vz. of the third magnitude, 1696, January 16.
6h. 24’, and 1711, December 5. gh. 13’, both mean time
and old ftile*. Sufpecting thefe might probably be days of
Algol’s variation, I computed the interval between them, but
could not find a period anfwerable to that which I have above’
determined. Upon examining more clofely the obfervations,
I find, in that of 1696, he marked at the {fame time the mag-
nitude of p Perfei; which, confidering efpecially the nearnefs
of e Perfei to Algol, makes this obfervation to be relied on for
its juftnefs, and lefs liable to any miftake of judgement ;
whereas the other obfervation of December 5, 17 Ef. is more
liable to error or doubtfulnefs, becaufe he did not then mark
the magnitude of 9 Perfei, or of any ftar of the fame magni-
tude near enough to Algol. Prefuming, therefore, on the juft-
nefs of FLAMSTEAD’s obfervation of 1696, to think that it
probably was made at a time when Algol varied, I compared
it with one of mine, viz. October 25. 6h. 39’, 1783, and I
find there is, in the interval between thofe obfervations, either
11,176 periods, each of 2d. 20h. 49’ 18”; or 11,177, each
of 2d. 20h. 48’ 56”. The laft, -as it approaches neareft to
the refults of my beft obfervations, I think, is the exacteft de-
termination of the period. This, however, all proceeds upon
the fuppofition that Algol varied at the time of FLAMsTEAD’s
obfervation, and alfo that the period is regular.
* Hiftoria Coeleftis, vel. I, edit 1725, p. 284. and 534. ©
- Vou, LXXIV. Qq ache
age Sie {Gooparece: on the Fvehas the
The folonae is a fhort abftradt of my late ee ca
Algol, when its leaft magnitude was accurately. determined. .
! eae 175" Hiky
App. rahe.
ie
10 52 About equal to 9 Perfei, thoogh Algol feemed to be:
rather brighter. !
ai, Evidently lefs than ¢ Perfei. |
eT 122 Ditto ; - but rather difficult to diftinguith. tbe from
each other. -
m1 30 Rather brighter than eg, and not fo bright 2 as Peake :
12 © About the brightneis of d Perfei, ond rather lef than
: 6 Trangult.
12 30 Brighter than 5 Perfei, and. rather not fo bright a as-
6 ‘Trianguli.
From thofe obfervations, by taking a mean ee
th. and (51h. 29". it Adee that its leaft bright
nefs happened at 11h. 14’; true, I think, to 5’.
, Otober 25.
40 It was confiderably lefs than g Perfei.
5 Ditto.
20 Equal to p Perfei, though Algol gaa rather lefss. a,
5 About equal to p Perfei.
50 Brighter than g, andalfo than 3 Perfei,
25 About the third magnitude, and equal to fe Trianguli,
35 Between the fecond and third magnitude ; : brighter than
@ Arietis, and rather lefs-than « Pegafis +
10 10 About the fecond magnitude; rather brighter than @ |
Pegafi, rather lefs than @ Caffiopez, and not fobright
as a and y Caffiopez.
ailiiid
SS COST ENON “Toro
1S)
se |
p (Rather
Changes of Light in the Star Algol, 291
me sai
h.
to 40 Rather brighter than Caftioper: but lefs than « ida Ye
ti o Nearly equal to, if not rather brighter than, y Caifio-
Pe and lefs than « Cafliopez*.
In 20’ afterwards it was of the fame brightnefs ; hbnke
we may conclude, that the variation has ended at
Be tih. O's
Its leaft brightnefs from the obfervations ee to
have happened at 6h. 55’; true, I om to 10’.
“November 11.
10 5 Third magnitude; not much different from « Perfei
and @ Triangult. eM
10 45 Between the third and fourth magnitude; believe equal
to d Perfei.
11 14 Lefs than o Perfei.
il 48 Ditto; but think it rather increafed.
Its leaft. brightnefs from thofe obizrvations appears to
have happened at 11h. 31’; true, I believe, to a
quarter of an hour. The weather was rather hazy.
‘November 14.
5 o Between the fecond and third magnitude, and lefs than
B Cafhiopezx.
5 45 A little brighter than @ Arietis,
6 5° Not fo bright as Arictis, and rather brighter than
On @ Triangult. |
‘[- 10 A little brighter than » Perfei, and believe equal to
tee pericn.
_‘* Algol’s ufual and-greateft brightnefs, by my later and more accurate obfer-
vations, is thus: a little lefs than « Caffiopex, brighter than 8 Caffiopex and
« Pegafi, and rather a little brighter than y Cafliopex.
Qq2 Lefs
292
App.
19 © Restor
OY OO OWN &
‘Oo
if
| Mr, Goovricke on the Period, &c.
oan
naa? Lefs than ¢ Perfe,
40 Ditto.
o Equal to p, though Algol appeared rather brighter,
15 A lwtle brighter than d and p Perfei.
By taking a mean between 8h. 25’ and 8h 40’, it
appears, its leaft brightnefs happened at 8h. 3275
true to 10 minutes. The weather was rather hazy
during fome part of this obfervation.
| November 17.
58 A little lefs than p Perfei.
15 Ditto.
35 Rather brighter than p Perfei.
50 A little brighter than p Perfei, but lefs than 3 Perfei.
5 Rather brighter than @ Perfei.
o Equal to 6 Trianguli, and brighter than ¢ and @ Perfei.
20 A little brighter than @ Arietis.
30 Between the fecond and third magnitude, and equal to:
@ Caffiopea, but lefs than @ and y.
so Second magnitude, and equal to y Caffiopee.
25 Nearly the fame, if not rather brighter.
The variation has therefore ended at gh. o’ nearly, and
its leaft brightnefs. by taking a mean between 4h. 58”
and 5h. 15’, happened at 5h. 7’; true, I believe,
to 10 minutes. The weather was fine.
have feveral more obfervations on Algol, where I have not
been able to afcertain its leaft brightnefs, which all happened.
agreeable to the period as above determined; vx. May 20.
July 5. and 22. Auguft 14. September 6, 9. 12. and 26. aes
ber
2+ §- 39. and 22. and December 7.
=
fyiag3 4]
XXIt. vee and Obfervations on the ‘Terra Ponderofa,
&c. By William Withering, M. D.; communicated by.
Richard Kirwan, Ef. FR. S.
Read April 22) £784:.
Seve. EE ONIN
Terra ponderofa atratas.
he fubftance was got out of a:lead-mine at Alfton--
| Moor, in Cumberland: I> firft: faw it in the valuable.
«olleé&tion of my worthy and ingenious- friend MattrHew:
Bouiton, Eig. at Seho; who, when he picked it up, con=
jectured from its weight that it contained:fomething metallic.
About two years ago I faw it in his poffeffion ; and partly from
its appearance, being different from that-of any calcareous f{par-
I had feen, and partly from: its great weight, I. fufpected it.to.
be the {patum ponderofum. |
A few experiments made at: the -moment:confirmed my fuf--
picions, at leaft fo far as to fhew that it contained a large pro-.
portion of the terra ponderofa united to fixed air; but I-did not’
then flatter myfelf that it would prove fo pure as-I. See S:
found it to be..
“Brofelides
294 Dr. WitTHerine’s Experiments and Obfervations
Profeflor Bercman, in his Sciagraphia Regni Mineralis,
publithed laft year at Leipfic, conjectures (§ 58.), with his
ufual fagacity, *¢ Terra ponderofa nitrata forte alicubi hativa
“\oocurrit,, a, neming tamen adhuc inventa, quod etiam valet
“¢ de aerata.”
- Iwas much delighted by ae dcreangn of a ieee eh
promifes to be of very confiderable utility in chemical inquiries,
and more fo when I found it to be a native of this country ;
for itis not improbable, that it may be met with in many other
mines, befides that at Alfton-Moor.
Mr. Bourton, with his ufual benevolence, prefented me
with a piece of it, part of which accompanies this paper, for
the infpe@tiion of the Members of the Royal Society.
\
_
More obvious Properties.
Its general appearance is not much unlike that of a lump of
alum; but, upon clofer infpe@ion, it {eems to, be compofed of,
flender {piculz in clofe contaét, but more or lefs diverging. .. It
may be cut with,a knife. , Its pari Bray is from 4, 300:
to.44338. | (| : dp
vor
It effervefces idle panes toa pees ey! the. blow-pipes
though not wery readily, Placed ina covered crucible, ina hot
parlour fire, it loft its tranfparency. | Pe
‘
After expofure to a moderate heat: in a melting furnace, it
adhered, to, the crucible, and exhibited figns of fufion ; but
was ‘not) diminifhed in weight, did not feel cauftic when ap-
plied)to the tengue, nor had it loft its property of effarvelean
with acids,
* ake
| on the Terra Ponderofa, &c. 295
Hence it 18 probable, that its lofs of tranfparency was rather
eccafioned by numerous fmall crack, than by any efcape of
the water of cryftallization, or of its aérial acid.
EXPERIMENTS.
A. 500 grains, diffolved in muriatic acid, in fuch a manner
that nothing but elaftic fluid could efcape, loft in folution 104.
grains, and there remained an , moluble refiduum of eis 3
grains. ee be :
2. In another experiment 100 grains loft in folution 27,
| grains, and there remained 0,6 of a grain of infoluble matter.
_B. 100 grains diflolving 1 in dilute muriatic acid, gave out 25
| ounce meafures of air. This aif was received in quick filver,
and when the {par was wholly diffolved,. the folution was
| boiled, in order to drive out what air might be lodged i im ‘ite
2. This air was heavier than atmofpheric air; it was readily ~
abforbed by agitation in water, it precipitated lime from lime=. -
water, and it extinguifhed flame. The water which, had ab-.
forbed it changed the blue colour of litmus’ flowly * toa red; :
fo that this elaftic fluid was undoubtedly fixed air. a6
C. The folution (B) by the addition’ of mild’ foffil’ fixed
alkaly, afforded a precipitaté which, after proper oo pig ‘
drying, weighed 100 grains.
De = precipitate, Wes being ae diffolved i in marine
pads @
.* Other acids turn the blue of litmus inftantly to a red, whilft water, | ‘imprega-
died with fixed’ air; ‘does not change the litmus immediately ;° but, after fome
Seconds, the red cotour begins’to appear, and then gradually grows more diftinch, .
F ia v : rs x
EW 4 sin Ret D: To.
: “y i 3
a Breit? ¥ spa e> J J ; Piphy
oe |
ee |
.
296 Dr. Wrruerine’s Experiments and Obfervations
D. To a faturated folution in marine acid mild fixed vege-
table alkaly was added; the earth was precipitated, and a quan=
tity of fixed air efcaped.
2. The fame thing happened when mild foffil alkaly was
added.
3. When cauftic vegetable alkaly was ufed, the precipitation
‘took place, but without any appearance of effervefcence.
4. 50 parts diffolved in marine acid loft, during the folu-
tion, nearly 10,5. ‘This folution, upon the addition of cauftic
vegetable alkaly, Jet fall a precipitate which, when wafhed and
dried, weighed 45,5.
5. Phlogitlicated alkaly precipitated the whole of the earth
from part of the folution D; for mild fixed alkaly afterwards
added to the filtered liquor occafioned no further precipitation. —
E. Part of the precipitates D. 1. 2. after expofure to a ftrong
heat in a crucible, was thrown into water. Next morning the
water was completely covered with an ice-like cruft, and had
the acrid tafte of lime-water in a very high degree. |
2. The fmalleft portion of vitriolic acid added to this water
occafioned an immediate and copious precipitation ; and when
this acrid water was diluted with 200 times its bulk of pure
water, the precipitation upon the addition of vitriolic acid was
yet fufficiently obvious.
3. A fingle drop of this acrid water, added to folutions of
tartar of vitriol, GLAuUBER’s falt, vitriolic ammoniac, alum, —
Epfom falt, felenite, occafioned an immediate precipitation in
all-of them. |
F. The precipitate thrown down by the cauftic vegetable
alkaly (D. 3.) was put into water, in expectation that it would
make lime-water; but neither upon ftanding, nor after boil-
ing, did this water exhibit any precipitation when concentrated
vitriolic
on the — » dea &e. 297
¥
en i aed
_ other Seiniae tafte.
G. Concentrated vitriolic acid was added to one portion of
the precipitate D. 3; concentrated nitrous acid to a fecond
portion; and marine acid to a third portion. No effervefcence
could be obferved, nor was there any appearance of folution.
After ftanding one hour water was added; and the acids, thus
diluted, were fuffered to remain upon the portions of the pre-
cipitate for another hour. They were then decanted, and fatu«
rated with mild foffil fixed alkaly, but without any appearance
of precipitation.
_.H. The part precipitated by the phlogifticated alkaly, when
mixed with nitre and borax, and fluxed by a blow-pipe upon
charcoal, formed a black glafs; upon flint-glafs, a white; and
upon a tobacco-pipe an opaque yellowifh. white one.
_ 2. Another portion melted with foap and borax ina crucible,
formed a black glafs, but without any metallic appearance.
I. The infoluble refiduum (A.) was boiled in water, the
water decanted, and mild fixed apealy added, but without any
fubfequent precipitation.
2. This infoluble powder was not attacked by the nitrous or
marine acids; but being put into vitriolic acid, and boiled a
confiderable time until the acid became highly concentrated, it
diffolved entirely, and feparated again upon the addition of wa-
ter. It will appear in the fequel, that the fame thing happens
to marmor metallicum, when diffolved by boiling in the acid
- of vitriol.
over. LAK. 7” Rr CO Ne
) Dr. WitneRine’s Experiments and Objervations.
f j eRe RS eye uy }
- = ' m8 ~ rr. ¢
r e my me : das 5 ? Pee ie 1 TR. PE wie a Aint
MALE Stine de Te ba ag BAG ' Pe ay ke. as Fe EAE RD A st LD bat
CONG .L.05S Ft 0. WS
HER appears, that 100 parts of this fpar contain —
‘ Bias PHT Lf
Terra ponderofa. pura - 78,6 e "is
Marmor metallicum ms ics pee, a4
J . <- mh * i \ x f ; “s p ' } } £7 ‘ 7 ‘,
Fixed air - = i) HO
é WEE ; Se i >
roo! siser bsp
ee ee
OBSPRVATIONS.
rft,, The quantity ae rail fixed: alkaly neceflary to faeurate.
an acid, prev rouflyuniced to the terra ponderofa, ‘contains mere
fixed air than i neceflar y to faturate that quay of terra pon-
derofa D- | “r
2dly, “The « terra ponderoia, when precipitated from an: said
by means of a mild fixed alkaly (O."T: 2); readily burns ‘to!
lime; and this. lime-water proves ree nice teft of the pre=
fence of vitriolic acid. E.-2. 3.
3dly, It is very remarkable, ‘tha tt the terra ponderofa: far,
iI
_
its native ftate, will not burn to lime. In the lower degrees
of heat it fuffers no change, as- was before obferved,. befides.
the lofs of its traniparency. When urged with a ftronger fire,
it Melts and unites to: the crucible,. but does not. become cauttic.
Y buried’ it in charcoal-duft in a covered’ crucible, and then —
<pofed’ it toa pretty ftrong heat; but it did net part with its
air, he
May we not conjecture, theny that as cauftic lime cannot
anite to fixed air without the intervention of moiftcre, and as
this. Bi {cems to contain no- water im its compoiition, that it
fo’ ig
on the Terra Ponderofa, der i | ue 299
—
is the want of water which prevents the fixed air iinittabigns its
élaftic aérial ftate ?’ This fuppofition becomes ftill more proba-
ble, if we obferve that ‘when the folution of the fpar in an
acid is precipitated by a mild alkaly, C. 1. 2. fome water en-
“ters into the compofition of the precipitate, for it weighs the
fame as before it was diffolved, and yet contains only 20 ounce
“meafures of fixed air, whilft the native {par contained 25 ounce
ameafutes ; ; fo that there is an addition of weight equal to that
of 5 ounce meafures of fixable air, or 33 grains to be accounted
for, Which can’ only arife from the water; and this precipitate,
‘thus united to’ Sala RE Sahel lofes its ee acid in the os.
Ei I. BE { ous :
‘athly, Prone? BercMawn fuppofes the terra ponderofa to
be a metallic earth *; its entire feparation from an acid by
‘means’ of the phlogifticated alkaly (D. 5-) certainly favours
~~ fuch a fappofition ; but, if it’be fo, it is evident from experi-
“ments H. Ly 2. that: other means than thofe commonly em-
, ployed muft be ufed to effet its reduétion..
sthly, The precipitate made by the cauftic vegetable alk ty
D. 4. taking fome of the alkaly down with it, and thus form-
ing a fubftance’neither foluble in ‘water nor in acids, 1s a very
curious phenomenon.» :
‘Tafterwards varied the experiment by adding the terra’ pon-
derofa lime-water (E.) to cauftic vegetable and cauftic: foffil
‘alkaly. In both cafes this infoluble’ compound was itnme-
diately formed; but not fo when cauftic volatile alkaly was ufed.
This comipofition of an alkaly and an earth certainly deferves
“more attention than Iam at prefent able to beftow. upon it.
é6thly, As it appears from ‘experiments D. 1.2. 3. 4. that
..* See preface to his Sciagraphia Regni Mineralis.
RR i2 ; fixed
uel
.300 )©60- Dr. WITHERIN e's’ Experiments and Obfervations
_ fixed alkalies, both mild and cauftic, feparated the terra ponderofa
from marine acid, I was at a lofs to know why. Profeflor Berc-_
_MAWN, in: his admirable ‘table of fimple elective attractions,
placed the terra ponderofa cauftica immediately. under the; vi-
triolic, nitrous, and marine acids, and confequently above the
cauftic alkalies. I. was interefted in the reality of the faéts,
becaufe I had fo feldom feen reafon to doubt. the obfervations of
that very excellent chemift, and: therefore made the i
experiments. pig gf en
To different portions of terra ponderofa Gilitat wae terra pon-
-derofa nitrata I added, drep by drop, cauttic vegetable, cautftic
“ foftil, and cauftic volatile alkalies. In every cafe the EARTH
- was thrown down; and I have fo often repeated thefe, experi-
_ments to fatisfy, myfelf and others, that Iam perfuaded the
terra ponderota cauftica ought to be placed below the alkalies,
except in the column appropriated to the vitriolic acid ; and-at
may be feparated even from that acid, by the vegetable, fixed
alkaly, if the alkaly be sent via feed | as will IPRs 1D the
next fection. 4p
athly, The neceffity for uf ing pure acids upon. many. ocea~
“ions, and the difficulty of obtaining them pure, are fufficicntly
obvious. The virrroLic AcrD, as made i in the Jarge way, .19
generally pure enough for moft purpofes. It is apt to,get co-
loured by inflammable matter; but this 1s feldom an _aneonve-
nience ;, and, when it would be-fo, it 1s ealy to drive it off: by
boiling the acid in a Florence flafk over a common fire, But
there is another caufe of impurity in this acid, which appears
upon diluting it with water; for then it becomes milky, and
in a fhort time a powder fubfides * | ee
* About two years ago F examined this powdery matter; both that which was ~
thrown —
on the Verra panderata, &ey. Kee ASE
oehe ae, ‘may be freed from this powder cither by diftilla-.
tion in glais veflels, which i Is a tedious. and dangerous procefs,
or by the affufion.of water; and, after bie powder has fubfided,
a gentle evaporation. w ill drive 8 mott ‘of the, fuperfluous
RAE oth. 2 |
. Nirrous ACID > may he freed from stale eee marine, acids,
s folution of filver in the acid of nitre,. as is daily practifed
but the MARINE ACID has not, to my knowledge, been puri-
fied by any. other method than the laborious one of re-diftilling
it from common falt. Ti 1s generally mixed with, vitriolic on
~and often in large proportion. There is no temptation, and
{earcely an opportunity, for it to be contaminated by nitrous
acid. From the-vitriolic a acid then it may be readily purified by
the addition of terra ponderofa cauftica diffolved in water, or
by, the terra oe falita. If the ae be ufed, a {mall
Ste Eun by dilticn write ete: ‘and oe Fea Ww rae ‘Drs Bite loves gave
me, being the refiduum of vitriolic acid dittilled to drynefs ina HAs elafs retort.
ift, Repédted boiling i im water, reduced 62 grains to 2 grains. +
.* adly, This! folution,. by’ gentle’ evaporation, afforded 5, grains of cryftals, as
hard and as taftelefs as felenite.
3dly, To thefe cryftals, re-diffolved in water, mild fof Lally was added, and
‘gq white powder’precipitated. 22); /. ; iat
, '4thly, This powder, after expofure: to a a pretty: insu ia was thrown inte
water ; part of it diffolved, and the water got Tee tate and other properties of
rh sZ
Sime- water.
sthly, The infoluble part (1.) fuffered no change by boiling in nitrous acid ¢
ene-half of it mixed with borax, and expofed to the blow-pipe upon gharcoal,
vitrified ; ; the other half, ‘mixed with borax and charcoal-duft, likewife vitrified.
py TORERESEONS: It appears, then, that the greater part of this fabiaace was
eal vite or felenite ; ‘the remainder a vitrifidble earth.
“I had before found, that the terra ponderofa vitriolata, -or heavy gypfum, would
diffelve in concentrated vitriolic acid 5 but always. feparated ina powdery form
upon the affufion of water; and now it appears, that calx vitriolata, or felenite,
does the fame. :
ki : portion
joa Dr. Wituentne's Exporiments and Obfervations
portion of the acid muft firft be tried in a diluted ftate, from
whence we muft judge how much of the terra ponderofa falita
the whole will require; or elfe the whole of the acid muft be
diluted with water. Whether we ufe the terra ponderofa dif-
folved in water or in marine acid; in either cafe the acid of
vitriol immediately feizes upon it, ane bNalities ‘id it in form
of an infoluble powder. ‘
As there are reafons for preferring the marine acid in fyi
of the nicer and more important enquiries of chemiftry, this
ready method of purifying it cannot but prove acceptable.
So, (Cat an Oc aan
Terra ponderofa vitriolata. BERcMan’s Sciagraphia,
§§ 58. 89. .
Variety,, Heavy Ghplite: Ponderous Spar.
‘Marmor Metallicum. CronsTEDT Min. og 18. 2.
19. C.
F rom. 5, Rakeback -hills near Ghigo A fort, with ss
cryftals, amongft the iron ore about Ketley in Shropfhire. Ta
the lead mines at Alfton-Moor.
More obvious Properties. ‘
White ; ; nearly tranf{parent, but has not the property of doue
ble'refra@tion ; compofed of lamin of rhomboidal cryftals ; de-
crepitates in the fire. Specific gravity from 4,402 to 4,440.)
4 4
v °°
EX P Ee
ox the ‘Terra Ponderofa, &c.
EXPERIMENTS,
A. roo grains expofed to a red: heat for one hour in. ablack .
Jead' crucible, loft five grains in: weight ; but as a fulphuteous
fmell was perceptible, I fufpeéted that a decompofition had
taken place, and therefore expofed: another portion to a fimilar
heat for the fame fpace of time in a tobacco-pipe. This had’
no fmell of fulphur, nor wasit diminithed in: weight.
2. Tt ts barely fulible under the blow-pipe ; ; but with borax
fluxes readily into. a. white opake glafs.
B. roo: grains, ground in a mortar, and wafhed' over ex-
tremely fine by repeated-additions of water, were boiled in the
fame water,.and, after fettling, the water was poured off. The
powder, when dried, had‘ not fenfibly loft weight.
2. To feparate portions of the wafhing water, were added
mild vegetable and: mild foffil alkaly; but without any appear-
‘ance of precipitation. Nutre of mercury gave a very flight
brownifh cloud, barely difcernible ;. and nitre of filver an. ex=
tremely flight bluifh appearance.
- 3. The fame powder, boiled’ again: in frefh water, did: not
affect the water at all; for it {tood the teft of nitre of filver
without any change.. : :
AS, Portions. of the powder B: were boiled in vitriolic, ni-
trous, and’ muriatic acids, of the ufual ftrength, for feveral:
minutes.. The acids were then faturated with vegetable fixed’
alkaly, but without any appearance: of precipitation, 1 nor had!
the portions of powder loft any weight. |
2. But when boiled in. vitriolic acid, unti! that acid became:
very much concentrated and nearly. red-hot, the whole of it
diffolved ; but, feparated again upon theraddition of water, was:
Bus 2g not
|
304 Dr. Wrruerine’s Experiments and Objervations
not altered in its weight, was not ated upon by acids of the
ufual ftrength, and had, under the blow-pipe, the properties
mentioned at A. 2. |
3. Some of the: folution in the ebocentnathdl vitriolic acid
was left expofed to the atmofphere, that the acid might flowly
attract water. Atter-fome days, beautiful cryftals appeared 1 ill
the fhapes of. ftars, fafcize, and other radiated forms. |
4. To another portion of this folution mild fixed yeast
alkaly was added; but the precipitate appeared to be the mar-
mor metallicum unchanged. a
D. One ounce of this marmor metallicum in fine powder
was fluxed in a crucible with two ounces of falt of tartar, un->
til it ran thin. This fubftance, boiled with water in a Flo-)
rence flafk, left a refiduum of fix drams.
E. This refiduum was thrown into water, and pure nitrous
acid added, until there was no more effervefcence. The un-
diflolved part weighed 52 grains. 7
F. This undifflolved part appeared to be the original fub-
{tance no ways changed; for it did not diffolve in nitrous or
marine acids, but did wholly diflolve in the greatly concen-
trated and boiling vitriolic acid, from which it was again t
rated by the addition of water. (C. 2.)
G. The felution D. was faturated with diftilled vinegar, “pil
then evaporated to drynefs, but with lefs than a boiling heat.,
‘The fal diureticus, thus formed, was wafhed away with alco-
hol. The remaining falt weighed 5 drams nearly.
2. This falt had the appearance and the tafte of vissiolatall
tartar; it decrepitatedin the fire; roafted with charcoal-duft, 1 it
formed a hepar fulphuris; and with muria calcarea gave a
precipitation of felenite.
5 a The
on the "Terra, Ponderofas &cw \/ 305
H. The falt, formed with the nitrous acid (E), thot reasllgh
into beautiful permanent cryftals, of a rough bitterifh tafte.
2: Some of this falt was deflaorated swith nitre and charcoal,
and the alkaly afterwards wafhed away.
3. The refiduam, being ‘theearth ‘of the imarmor, metalli-
cum, was very white, burnt to lime, and‘again formed an ans
foluble compound with acid of vitriol... |
I. roo grains of terra ponderofa aérata were diflolved in di-
luted marine acid. Vitriolic acid was‘dropped into this {folu-
tion, until no-more precipitation errfued. ‘The precipitate, after
very careful wafhing and drying, was’expofed to.a red heat in
@ covered tobacco-pipe “for half an ‘hour: when cool, it
weighed 117 grails. OG G14.
2. 50 grains of terra ponderofa aérata in a lurmp were put
into diluted. vitriolic acid; but the action of the acid Bone it
was hardly fenfible, ‘even’ when made het. ,
Marine acid was then added, “and after Yome time-an effer=
vefcence appeared. The terra ponderofa’ vitriolata, thus. formed,
after proper wafhing’and ‘drying, ‘was expofed to-a: red heat for
an hour : | Sts then weighed 5854 a |
CONCLUSIONS
ft, It appears that;the marmor metallicum is compofed of
vitriolic acid and terra ponderofa, D. E. F. G.H.
_ 2dly, That this compound, though probably foluble in wa-
ter, has fo little folubility as valmoft to efeape detedtion by the
niceft chemical tefts, B. 1. 2.
3dly, That at is not Hite in acids of the ufual ftreneth ;
but that ‘it perfe@ly and entirely diffolves in’ highly concen-
Vor, LXXIV. St trated
trated vitriolic acid, from which it again feparates entire and
unchanged upon the affufion of water, C. 1. 2.
4thly, That it cannot be decompofed (via humida), by roll
fixed alkaly, C. 4.
sthly, That it may be Netomsgesi (via ficca) by the vege-
table fixed alkaly, D. E. G. H.
6thly, That it may be decompofed by inflammable matter,
uniting to its acid, and forming fulphur ; but that it cannot be
decompofed by heat alone, A. 1.
“thly, From experiments I. 1.2. it appears, that 100 pas
of this fubf{tance contain
306 «=Dr. WituErRine’s Experiments and Obfervations
Vitriolic acid pure “ 32,8 ‘
‘Terra ponderofa pure 67,2
YOO
For the 100 parts of terra ponderofa aérata made ufe of in the
experiment I. 1. would lofe during the folution 20,8 of fixed
air (§ 1ft, A.); then, deduting 0,6 for the marmor metalli;
cum contained in the terra ponderofa aérata (§ 1ft. A. 1. 2),
there remains 78,6 of pure terra ponderofa. This, when fa-
turated with vitriolic acid, and made perfectly dry, weighed
1173 confequently it had taken 38,4 of vitriolic acid.
OBSERVATIONS
The apparent infolubility of terra ponderofa aérata in the
diluted vitriolic acid (I. 2.) can be accounted for by remarking,
that the moment the furface of the lump was ated upon by
the acid, an infoluble coat of marmor metallicum was formed
upon it, which effectually precluded any further operation of
the acid.
Profeffor
_— ;
on the Terra Ponderofa, &c. 307
Profeflor BERGMAN, in order to obtain the earth from the
terra ponderofa vitriolata, directs the latter to be roafted with
fixed alkaly, and the duft of charcoal; but I have always done
it by charcoal duft alone, though probably this method may
require a greater degree. of heat.
It has been remarked, that terra ponderofa and calx of lead
refemble each other in many refpeéts; and I muft add, that the
vitriol of lead diffolves in the highly concentrated vitriolic acid
much in the fame manner that the marmor metallicum does,
and like this too feparates upon the affufion of water; but I”
never obferved it difpofed to cryftallize.
The marmor metallicum may probably be ufeful in fome
cafes where a powerful flux is wanted; for I once mixed fome
of it with the black flux, and expofing it toa pretty fharp heat,
it entirely ran through the crucible. May not, therefore, fome
of the more common varieties of it be ufed advantageoully as
a flux to fome of the more refractory metallic ores ?
Sh we oh ol OeN oa
Terra ponderofa Vitriolata.
Variety, Calk or Cauk.
Marmor Metallicum, Cronstept Min. § 18. B?
Plentiful in the Mines in Derbythire.
More obvious Properties.
Of a white or reddifh colour; cryftallized in rhombotdal
jaminz, but thefe very much intermixed and confufed. Lofes
a {2 little
|
Ok pa '
'
308 Dr. Wituerine’s Experiments and Obfervations <M
little or nothing of its weight by being made red-hot, Specific
gravity 4,330.
ESOP BRR NOT Re
_ A. Ground in a mortar, and wafhed over, the wafhing wa=
ter, when decanted, gave no precipitation with mild vegetable
aikaly; but with nitre of. filver and nitre ef mercury the
lighter cloud imaginable. ;
B. 100 grains boiled in marine acid Sea A after proper
wafhing st drying, 99,5.
C. The acid folution B let fall a Pruffian blue upon the ad=
dition of a fingle drop of phlogifticated fixed alkaly; and,
when faturated with mild foffil alkaly, afforded an ochre
loured precipitate.
D. This precipitate, colle€ted and’ wafhed, weighed half a
grain. It was roafted with tallow, and then was wholly, ate
ea by a magnet. q
EK. A quantity of the cauk, finely powdered, was rio
with charcoal-duft, and roafted in a crucible at a white heat,
for five hours, frefh charcoal-duft being occafionally added. Ie
gave out a {trong {mell of fulphur.
F, To this roafted cauk nitrous acid was-added, which dif=
folved the greater part of it; producing, during the folution;.
fome effervefcence, anda ftrong fmell of hepar fulphuris.
G. Some of this folution, after proper evaporation, afforded
beautiful cryftals, not deliquefcent, exaétly refembling thofe
obtained from the marmor metallicum, (§ II. H.).
H.\To other portions of the folution F, were added fixed!
vegetableand:foflilialkalics, and likewife volatile-alkaly,, each:
of -which:precipitated:the.carth:from.the acid,
1. This
on the Terra Ponderofa, &c. 309
E. This earth, after expofure to a white heat for one hour,
became cauftic, and made lime-water, fimilar in properties to
to that mentioned at § Ift. E.
K. Some of the part not acted upon by the nitrous acid iF,
difiolved entirely by boiling in highly concentrated vitriolic
acid, and wholly feparated again by the affufion of water. More
Water was added, and the whole was boiled again; but the fil-
tered liquor gave no figns of precipitation upon the moft liberal
addition of mild fixed vegetable alkaly.
CON; © EUS: OuN) Ss.
It appears, therefore, that 100 parts of Derbyfhire cauk
contain.
Marmor metallicum = - 9955
Calciform iron. = - 5:
100
And it is probable, that the redder pieces contain a little more:
iron.
Bee et oN! ay
Terra ponderofa vitriolata.
Variety, radiated Cauk.
Gypfum cryftallifatum capillare. CronstepT Min,.
pie R.
From Pennely by he Bog, near Minfterley, in Shropthire,
_ fifteen miles from Salop, on the road to Montgomery.
Mor €°
gio. = Dr. Wiruerine’s Experiments and Obfervations
More obvious Properties.
Somewhat glofly like fatin; yellowith-white, opake; com-
pofed of flender {picule fet clofe together, and pointing from a
center. | |
In fome pieces there are concentric circles of a femi-tranfpa-
rent horn like appearance. It is not very brittle; may be
fhaved with a knife; lofes little or nothing of its weight by
being made red-hot. Its fpecific gravity 4,000; but after
foaking one night in the water 4,200, or more.
Ek PE RO MOE NPs.
When treated in the fame manner that the Derbyfhire cauk
was, in the preceding feCtion, 100 parts of it appeared to
contain
Marmor metallicum = 9757
‘Calciform iron - - 253
100
Sufpeting that the prefence of fo {mall a proportion of iron
could hardly occafion the whole of the apparent differences be-
twixt the Shropfhire and Derbyfhire cauks and the marmor
metallicum ; and thinking it not improbable, that they might
contain lead; I mixed fome of them with charcoal-duft and
borax, but could not by means of the blow-pipe produce any me-
tallic appearance, although vitriol of lead, treated in the fame
manner, was readily reduced.
Ithen mixed four parts of cauk with one part of vitriol of
lead; the lead could {till be reduced, though not fo readily as
befere.
GENEBAL
on the Terra Ponderofa, &c.
GE N ERA 7 O BS BUR WV) Ay Tei O Re se
The terra ponderofa feems to claim.a place betwixt the earths —
and the metallic calces. Like the former, it cannot be made
to aflume a metallic form; but, like the latter, it may be pre-
cipitated from an acid, by means of phlogifticated alkaly. In
many of its properties it much refembles the calx of lead;
and. in others, the common calcareous earth, but full feems
fufficiently different from that to conftitute a new genus, as will
appear from a little attention to. the following circumftances.
Terra ponderofa,,. ‘Heura caledres, "14
When diflolved in water, preci- | Diffolved in water, does not
pitates. upon the addition of | . precipitate upon the addi-
the {malleft portion of vi- tion of vitriolic acid..
triolic acid.
Its gypfum, therefore, is in- | Its. gypfum, therefore, is fo-
foluble. ) waduble,.
With the nitrous and marine | With nitrous and marine acids
acid, forms cryftals which | forms falts fo deliquefcent
do not deliquefce. 7 that they cannot. be kept in
: | a cryftallized. form.
Decompofes vitriolic falts v7a | Does not decompofe vitriolic
humida. falts.
Tt has been: called terra ponderofa, or heavy earth, upon
account of the great fpecific gravity of its gypfum; its fpar
is likewife heavy enough to countenance fuch an appellation ;
but the earth itfelf does not appear to be a heavy fubftance,
and I imagine the great weight of its compounds with the
vitriolic and atrial acids 1s owing to the abfence of water.
Birmingham, Nov. 1783..
RASA
XXIV. * Seettppppn dit Paffege de Tiwues oe te Dy ‘fue ‘2
\ Soleil le 12 Novembre, 1782, faites al’ Obfervatoire Royal de
Paris, avec des reflexions fur un Ge qu i fe fat fentir dans ces
mimes Obfervations femblable & celui dune Réfraétion dans
LY’ Atmofpbere de Mercure. Par Johann Wilhelm Wallot,
Membre de TP Académie Eleétorale de Sciences et Belles Letires
de..Manheim, @c. Communicated by Joleph Planta, Eff.
ee. Rw, *
,
Read April 29, Mads
ES paffages de Mercure fur le difque du (ha fonit d’aus
tant plus intéreffans pour les aftronomes,.qu’ils dons
nent principalement le moyen de determiner avec plus°d’exacti«
tude la pofition des noeuds de fon orbite, et que la difficulté de
voir cette planéte dans fés autres afpects avec le foleil en rend
les obfervations plus précieufes. |
. Deux circonftances affez defavantageufes qui deqaleage ace
compagner particulierement le paflage dont il’s’agit ici, favom
Ja proximité du foleil de ’horizon, et Mercure paflant trop»prés
du bord de cet aftre, femblaient par leur nature offrir trop d’in-
conveniens pour en efpérer des obfervations bien exattess
cependant l’encouragement ‘qu’a donné le beau-tems qu'il fit
toute la journée du 12 Novembre, nous ayant fait apporter uné
plus grande attention aux obfervations, nous autorife mains
tenant a en avoir une meilleure opinion. Je crois pouvoir
afiurer fans oftentation d’y avoir réuffi affez pour étre fatisfait
des miennes, et pour ofer les garantir autant que Ja nature des
2 chofes —
Obfervations de Paffage de Mercure, Ge. rg
' chofes peut le permettre. Si je puis me flatter d’avoir obtenu
de'ce paflage une obfervation trés’ exacte et peut-étre Ta’ plus
complette, je ne diffimulerai pas que jé dois en grande’ partie
cet avantage 4 M. pe Cassint qui, m’ayant laiffé la meilleure lu-
nette* qu'il yait 4 PObfervatoire Royal, m’avait mis par 14 dans
-le cas d’employet la plus grande rau an pour meriter par
lexaétitude de mes opérations la confiance qu'on me gees
dans une occafion aufli importante.
3. Nous avons fait (M. ps Cassini et moi) toutes les obfer-
vations néceffaires pour conftater avec la plus grande exactitude
Vétat de notre pendule; et, en réduifant mes obfervations aw
tems vrai, je n'ai pas’méme négligé les dixicmes de {econde.
Cette précifion fcrupuleufe paraitra peut-ctre fuperflue dans de
pareilles obfervations, mais en verra par la fuite de ce Mémoire
les raifons qui m’y ont déterminé. Voici mes’ obfervations
dans le méme ordre o0 elles fe font faites, ef réduites aw teme
vrai de la méridieniie de l’Obfervatoire Royal de Paris,
“Sortie
‘Tems vrai.
ht t Ph ee ) % ;
4 2 56 28,8 Je foupconne la planéte. Contaé extérieur de Pentrée.
- Sis A 28,8 J’eftime Mercure entré 4 moitié, Centre de & fur “
Entrée bord du®.
/ 4 3 2 3,8 Contaé intérieur de Ventrée.
3 3 45,8 Mercure abfolument détaché du foleil,
En méfurant le diamétre de Mercure fur le
difque du foleil je Vai trouvé par deux fois
exactement de la méme quantite, {avoir
de 9 sages du micrometre objecif, qui
valent 9,535 de degrés du grand cerclei
4 17 18,4 Contact intérieur de la fortie.
4 20 35,4 Le centre de Mercure fur le bord du foleil. -
4 22 §3,4 Contact extéricur de la fortie, Mercure totalement perdu
de vue. FOE STREETS
fi Sy pe
* Une excelleate lunette achromatique de DoLionp de 3:pieds.
Vou. LXXIV. Tt ; Le
314 Obfervations du Paffege de Merciire
Le bord du foleil était fi ondoyant que Mercure, aux ‘ae
proches de fa fortie totale, reflemblait exatement a un corps
flottant fur les vagues d’une eau fortement agitée, et qui tantdt
‘difparait entiérement, tantdt élevé par les vagues fe montre en
‘partie et quelquefois tout entier. Ces vagues ou ondulations
allaient toujours dans le méme fens du N. Oueft au Sud Eft.
Leur mouvement était affez rapide, et c’eft précifément la rapi-
dité dece mouvement qui m’a fingulierement favorifé Pobferva-
tion du contact extérieur de la fortie de Mercure, pee He De
la perdais jamais de vue qu’un inftant.
Je terminerai le détail de mes obfervations par aflurer,. que je:
n’ai pas appercu la momdre apparence d’une atmofphére ow
nébulofité autour de Mercure pendant toute la durée de fon
paflage, quoique la lunette me repréfentat tous. les objets.
trés diftinctement. J’ai toujours vu le disque de Mercure bien,
noir, et également bien termine dans. toute fa. circonférence qui
me paraiflait toujours tranchée nette;. furtout dans. le commen-
cement ou les ondulations étaient moins: fortes. jufques vers. le
milieu du paflage. Mais cela ne m’empéchera pas d’étre trés.
perfuadé de Vexiftence d’une atmofphére autour de Mercure,
¢omme autour de tous les-corps celeftes, et qu’on peut fort bien”
Vavoir appergue dans ce paflage fous un. ciel plus pur et plus.
beau. que celui de Paris.
Reéfultats du calcul des obfervations precédentes felon leurs diff
Serentes combinaifons..
4. La methode que j’ai fuivie pour réduire: les obfervations.”
de ce paffage au centre de Ja terre, m’eft en quelque forte par-
ticulieze ; 5. mais comme elle n’eft pas entiérement nouvelle puif-
qu elle
par M. J. W. Watror. | Bry
qu’elle ne différe de toutes les methodes connues qu’en’ ce que
je lai fimplifice én la rendant abfolument direéte, je me con-
tenterai d’en donner une idée générale. Je n’ai employé dans
mes calculs que ce qui eft donné direftement par obfervation,
ou bien des quantités plus exactement données par les. tables,
telles que le diamétre du foleil, fon mouvement horaire et celui
de Mercure. Mais ce qui caractérife effenticllement cette mé-
thode, c’eft qu’en combinant les obfervations toujours enfemble
deux a deux, on a la durée ou le tems écoulé d’une obfervation
a Pautre qui eft une des principales données du probléme, et la
plus exaéte qu’on puifle fe procurer par obfervation. Or, quand
Yobfervation nous fournit directement des données exactes, je ne
vois abfolument pas la néceflité d’en aller chercher de moins
exactes pour les faire entrer dans le calcul. C’eft pourtant ce.
que font quelques aftronomes modernes*, qui, en recommen-
dant dans leur Traité d’Aftronomie de calculer les obfervations
f{éparément afin, difent-ils, de multiplier les réfultats et d’en
déduire plus exactement par un milieu la quantité qu'on
cherche, font obligés pour cet effet de fuppofer 4 peu prés
connu le milieu du paflage et la plus courte diftance des cen-
tres}. Ce raifonnement, auffi cloigné des principes de la géo-
metrie, que des regles de l’analyfe, me parait encore illufoire
quant a l’exactitude qu’on efpéere obtenir de la multiplicité des
réfultats ainfi déterminés ; voici pourquoi.
5- Je fuppofe pour un inftant qu’on prenne av hazard deux
obfervations, et qu’on les calcule feparement chacun f{uivant ce
précepte; il ef certain que fi l’on ne fuppofe pas le milieu du
paffage et la plus courte diftance des centres tels que les don-
* Principalement M. DE ia Lawpe dans fon Traité d’Aftronemie, edition de
1771, livre XI, art. 2152.
Ibid. art. 2062 et 2063. shi ee
a Ttez2 neraient
gies Objervations du Paffage dé Mercure
neraient directement ces deux obfervations combinées enfemble,
on doit trouver, pour la quantite qu’on cherche, deux réfultats
différens, et qui différeront dautant plus que la fuppofition —
qu’on-aura faite fera plus éloignée: de la véritable.. On prend
donc alors un¢mulieu entre les -deux réfultats et l’on 8’ imagine
avoir trouvé la vérite; mais il me femble qu'il eft tres permis
d’en douter, car; outre qu'il y a bien des cas ot |’on ne peut pas
regarder le réfultat moyen comme le véritable, ici ce n’eft pas
méme admiflible, puifque le milieu du paffage et la plus courte
diftance des:centres font deux quantités qui dependent l'une de
Vautre, et. qu'il eft impoffible de les fuppofertelles précifément
quelles fe conviennent relativement a deux obfervations déten-
minées, 2 moins que ce ne foit un effet du hazard. Or fi je
fuppofe maintemant qu’on prenne les deux mémes. obferva=
tions, et qu’on les combine enfemble, il eft clair qu’on ne trows
vera qu’un feul réfultat pour la quantité cherchée, maisice fera:
précifément la méme qu’on aurait eue par un milieu entre les!
deux réfultats trouvés fuivant autre maniére fi Poa! y avait: fait
une fuppofition qui s’écartat peu de celle qu'il convenait de faire.)
Il s’en fuit done qu’on ferait arrivé au méme but par les: deux,
methodes, mais avec cette différence gue les quantités deters:
minées d’aprés la méthode des combinaifons font dans. tous les.
cas de vrais réfultats:tels que les donne véritablement Vobferva-
tion, tandifque d’aprés Vautre ‘ce ne font que des réfultats:
fictifs ou approchés. Le caleul dévient a. la verte plus Jong,
lor{qu’il y a plus dé trois obfervations ; parceque’ alors le moms)
bre des combinaifons qv’on en: peut faire: deux +a deux, confés
quemment auffi le nombre des réfultats qui en provienmenit,,
furpaffera toujours celui des obfervations. Or fi pour deter-
miner une quantité quelconque daprés ‘tine méthode on tifque
de trouver des réfultats inexatts, et que d’ apres | ‘une autie mé~
thee. 7 = 31 thode
ony Pali Ma JQ Wiawnors a6 34%
thode on peut déterminer la méme:quantité fans courir ‘ce dan-
ger, il eft inconteftable que celle-ci eft préférable a) l'autre;
Lorfgu’on ne peut avoir que des obfervations ifolées, il faut
bien alors fe réfoudre a les calculer feparément, mais encore
avec la reftriction que les quantités qu’on fuppofera connueés
foient données par d’autres obfervations, qui étant dans. le cas
d’étre combinées deux a deux, foient clles-mémes trés exattes!
Hi eft donc aifé de conclure de tout ce que je viens de dire. qué
Ja maniére de calculer feparément chaque iobfervation; non
feulement ne procure pas les avantages qu’on ‘en attend pour la
multiplicité des réfultats, mais elle eft eucore moins exatte que
celle de combiner deux 4 deux les obfervations, ainfi que l’en-
feignent les plus célébres aftronomes. | Je‘ne me? fuis permis
d’entret dans cés details que pour’ prouver'a la Société Royald
que je ne mé fers jamais avec'confiance d’aucune | méthode’ fing
‘Pavow examinee auparavant en la pera a ain fi eve? ue
feronde fois iii esl aiiiy.eo oe Be Lobes
6. Jai calculé le'liew du foleil et de vinekinn pariles tables ae
Hateey pour 23:hl g$hi vet 43h. efpaceide temisqui eo
lame 4 peu prés par fon miliew toute la’ durée mY ‘paffabe det
as ai trouvé,
#2h9o'temsvraifA 2h, 30’ t. v. {4 4h. 30’ t. ve.
Ss. ORR Nan SRO BAN oC ian
F129, 22 AO 20,25 114,8 17.20) 25) A hoe
Son afcenfion droite 7.17 55 5573\27 17 58 28,417 18. E 1,5.
~Sadéclinaifon - - auftrale PP GE AGO! a7 S220,00" 996s TOME
La longit. géocentrique de Mercure|7 20 32 2,9/7 20 28 40,817 20 25 18,4
La longitude du folcil de
Salatitude - - = boréale O14 21,0 O1LG 22.615" O° 1G. mare
Ce qui me denne entre2th.et 3th ety ctgh
° f dt haey: v?
Le mouvem horaire relatif Merc. fur l’écliptique de §. 335 3. 5 53> §
L’inclinaifon de l’orbite relative fur l’écliptique de | 8 38 33, 8 | 8 14 28, 5.
Popponsesn. | horaire relatifde Merc. dans fon orbite| § 57,05 | 5 57:19
Ie
ae Objervations du Pafface de Mercure
-ude me fuis fervi de Vinclinaifon et da mouvement horairé
qui avait lieu entre 2h. et 34h. dans le calcul des obfervations
du-commencement, et l’inclinaifon avec le mouvement horaire
qui avait lieu entre 3% h. et 43h. m’a fervi pour la fin du paf-
fage. Quant aux autres élémens, j’ai employe le diametre du
foleil de 32’ 24’",53 celui de Mercure de 9"’,535 comme je
l'ai méfuré fur le difque du foleil pendant le paffage, et la pa-
rallaxe horizontale du foleil dans fes moyennes diftances de
8’ ,7 telle que je l’ai établie dans mon Mémoire fur le paflage
de Venus en 1769. D’owt j’ai conclu la difference des paral-
Jaxes horizontales du foleil et de Mercure pour le jour dy paf-
fage 12 Novembre de 4’,088.
7. Avec ces éléments j'ai. calcule les obfervations des con-
tacts en ne négligeant pas méme les milli¢mes de feconde dans
certains cas; je.n’al mis cette fcrupuleufe exactitude dans tous:
mes calculs que parceque je voulais m’affurer dans le cas ob je
viendrais a trouver des differences entre les réfultats de méme:
denomination que je n’euffe a les attribuer uniquement qu’aux
obfervations. La table fuivante renférme les réfultats les plus
unportans de ces.calculs. |
‘Table
Table des réfultats du calcul des obfervations des contaéts et
du centre de Mercure. |
Contacisintéricurs} Contacts extér.
Sr ree eee eee |
—
ena aan
x SoS A Se a
¢ ae La
a ai Dh Hee he Geers
aS . ’ entrée Beep girs 2 KONG pe 2 58y-aRes
mrevraiede l’obfervation rice <1 1B 4 422 53,4 | 4 20 36:4
ee donnée direétement par lobf, renga 1 26 24, 6 122), 740
iscourte diftance des centres vue | zt
la furface de la terre J hatha iu 5 a7 ae
evraie du milieu du paffage | nS |
lecentredelaterre | {| 3 39 47> 4 Doe aio! 3.39 39,7
urte diftance des centres |
ucentre de la terre J Ce eae 15 46, 4 15 449
lution de iat + 2 59,45 + 2 34,38 + 2 42,9
ntre de la terre fortie = AG FOUN si aia so — 2° 20.7
vr. de Vobfervation f entrée} 3 ike hl be: (oy sea Ri OF 17
fivée pour le centre 4 | fortie 4 14 31,70 4 (20% ginyt3 Ee I aa
¢ du paflage pour le centre
a 3° P bh oeg g@ 28,45 1 21 28,02 1 16 54,0
vraie de !a conjonction de | |
etcure et du foleil Feats “Or a 2 54,8 ue aay!
ude de ¥en conjonétion don-1| 5. ° / ” Seay ey ne ee Nee he
ar obfervation i 15 55,1 15 §6,4 15 54,
de du foleil ow de Mer- }
en conjonétion FL 120 80) S808) 7) 202003757) lm sbi aGnag,
de de Mercure: en: conjonc-}
donnée par les tables ceur| 7 20 27 8,4 | 7 20°27 8,3 20. 27 850
a aberration 2
de 3 end donnée par les | ;
a Bien upbeat Fi 15 $97 15. 50,7 15 50,5
A | en longitude | — 30,8 } ~ 30,6 ~~ 3157
ij pe tables te latitude | + 4,4 + 5,7 + 4,
jidug
pica { wae as &
Ya
3
Pdoptant la latitude de § au moment de la g donnée par les contacts intérieurs de 15’ 55751.
(} /
1 15 45 22,8 em fuppofant |’inclinaifon de Vorbite 7 © Oavec M. Cassing.|,
1 15 44 55,7 en fuppofant Vinclinaifon de Porbite 6 59 20 avec HaLiey,
8. Lon.
7
Le Obfervations du Pijtibe b meow “a
8. Lon voit par cette table que les contacts intérieurs dot
nent, Vheure du milieu du paflage 2 a 3 dixiémes de feconde. ;
la méme que | eS contacts extérieurs ; yan de la feat
a 1,6 prés la méme*, et la plus courte diftance ae centres
ain que la latitude de Mercure en conjonction de'1,3 plus pe- _
tite. Quant aux deux obfervations du centre de Mercure fur les _
bords du foleil, elles dohnent le ane du paflage de 8’’,7 plu-
tot que les contaéts intérieurs, et la plus courte diftance des
centres ainfi que Ja latitude de Mercure en conjonétion de z
dixiémes de feconde feulement plus petite. Cette différence:«
dans l’heure du milieu du paflage ne peut venir que de la ma- ~
niere dont j'ai eftimé le centre de Mercure; carilyad’ abord ,
feconde pour feconde le méme intervalle de tems. entre les deux
contacts de entrée qu’entre ceux de la fortie, c’eft a dire V un et 4
autre de 5’ 35’. Enfuite je trouve qu'il s’ctait écotle 2" 6"
depuis le contact extérieur de Pentrée Uli au moment ov jlab.
eftimé le centre de Mercure fur Je bord du foleil, aw Tiew de”
17” qwil y aentre les pareilles obfervations de la fortie ; mais’
cet intervalle de tems devant tre le méme pour l’entrée et pour _
la fortie, la ditference 17” fait voir que j’ai eftimé le centre de ~
Mercure plus prés du contact extérieur a l’entrée qu’a la fortie,,
ce qui devait auffi avancer Pinftant du milieu du paflages or la’ |
moitié de ces 17’” fait précifément les 8’ dont. le milieu du
paflage eft arrivé plutdt felon cette obfervation que felon’ celle”
des contacts intéricurs(puifque Perreur de l'une des deux obferva= ©
tions n’eft que la moitie fur le milieu du pafiage). J'ai done ™
marqué Vinftant de l’obfervation du centre 4 Pentrée plutdt qu'il
sony
-* Lrinftant de la conjonction difftre de 1’”,6 quoique celui du milieu du RE
ne dititre que de o’’,3, parceque la portion de Vorbite relative comprife entre le
anilien <u patiage et vi corjonction eft plus grande pimple plus grande, diftance
i + gaat
és centres,
ne
ae)
re 3
par M. J. W. Watror. B22
*«
fe fallait ; car’je pencherai toujours a croire plutét ho ceft fur
celle de l’entrée que doit tomber Verreur,- parceque mayant pas
encoré vu Mercure fur le difque du foleil, ie ne pouvais pag
juger de fa grandeur auffi bien -qu’a la fin apres Vavoir vu per
dant toute la durée de fon’ paflape. C’eft auffi en partie par
cette méme raifon, jointe a celle qu'on ne peut pas eftimer avec
quelque précifion le centre d’un corps qu’on he voit pas en=
ticrement, que je puis avoir obferve le centre de Mercure fur le
bord du foleil trop tot a Pentrée, et trop tard a la fortie rela-
tivement aux obfervations des contacts. Cette difcuffion, en
apparence d’ailleurs peu importante, devient. ici d’une’ brande
néceffité, parcequ’il s’agit de montrer les défauts de deux ob-
fervations que je ne rejette qu’avec beaucoup de regrets; car
Pobfervation du centre de la plancte fur le bord du foleil n’étant
pas affectée de l’effet de plufieurs elémens (le diamétre de la
planete et l’effet d’une atmofphére quil’envelopperait) que nous
connaifions fouvent mal, ou que nous ignorons abfolument,
offrirait des avantages réels, fi elle pouvait fe faire avec une
certaine précifion. :
9- Quoique les réfultats de 1 mes calculs s’accordent aflez pour
infpirer quelque confiance, je n’ai cependant pas été trop fatif-
fait de trouver la plus courte diftance des centres de 1,3 plus
grande par les contaéts extérieurs que par les contacts intérieurs.
Cette difference annonce une erreur dans les durées, Ou la
durée du paflage entre les deux contacts extérieurs eft trop pe-
tite, ou celle des Contaéts intérieurs eft trop grande. Mais je
me fuis impofé la loi de ne jamais faire aucune correction &
mes obfervations lorfque je ne les ai accompagnées d’aucune
Marque qui me faffe douter de leur bonté; je ne trouve donc
aucune raifon qui m’autorife a changer la durée des. contaéts
intérieurs, et quand je voudrais m’écarter ici un moment de mes _
Von. LXXIV. U nu prin-
ey
322 Obfervations.da Pafjage de Mercure — |
principes pow aa la durée des contaéts extérieurs, ieee |
le pourrais, faire qu’en confidération de lincertitude avec la~ _
quelle on peut eftimer le contact extérieur de l’entrée trop tard, ,
et celui de la fortie trop tot, ce qui eft toujours probable; mais
je ne la pourrais augmenter que tout au plus de 5 a 6 fecondes
de tems, puifqu’on a vu dans l'article précédent qu'il n’y a que
17” @incertitude fur l’eftime des deux ebfervations du centre de
Mercure fur les bords du foleil qui comparatiyement entre elles-
mémes fe font beaucoup, moins exactement. Or ces 5 ou 6
fecondes d’augmentation far la durée extérieure ne fufiifent pas
a beaucoup prés (car 11 en faudsait 106’) pour. réduire a zéro la
difference qui fe trouve entre les deux. valeurs de la plus.courte
diftance des centres. Il faut donc chercher ailleurs que.dans
les obfervations la caufe de cette, difference. C’eft ce que je
crois pouvoir trouver dans l’effét d’une atmofpheére fuppotée au-
tour de Mercure, on d’une caufe femblable., tes al :
10. D’aprés les recherches que j’ai faites fur l’atmofphere de
Venus a l’occafion de fon paflage en 17,69, et dont jai établi et
démontré les principes dans un petit Traité complet fur les paf-
{ages de Venus et de Mercure, j’étais. prévenu que la eircon-
ftance caractériftique de ce paflage de Mercure qui était fi defar
avantageufe A Végard de l’utilité. qu’on en retire pour perfedtion-
ner les tables, devait étre extr€mement favorable Ada détermi-
nation de effet d'une atmofphére qui environnerait:Mercurey
puifque la planéte paffant fort pres du bord du, foleil, for,
mouvement fe faifait trés obliquement a ce bord, et agrandiffait
beaucoup effet d’une atmofphere. En conféquence j je me fuis
finguliérement appliqué a obferver ce paffage et principalement
les quatre contacts avec la plus grande attention, afin ce me
procurer des obfervations fuffifamment exa¢tes pour pouvoir
m’en fervir avec avantage 4 determiner l’effet de cette atmo-
Sphere,
par M. J.W. Wattor. ~ 323
fphére, ou du moiris 4 m’affurer de fon exiftence. Je puis dire
maintenant que les réfultats de mes calculs, de quelque maniére
que je les combine, en fuppofant l’obfervation et le diamétre de
Mercure employé dans mes calculs rigoureufement exacts, m’in-
diquent la préfence d’un effet femblable 4 celui d’une réfraGtion
ou inflexion que fouffriraient les rayons folaires dans leur paflage
aupres du globe de Mercure. Voici comment. |
11. J'ai démontré dans Je petit Traité que je viens de citer
que la combinaiton des deux obfervations des contatts extérieurs
doit donner le méme inftant pour celui du milieu du paflage
que la combinaifon des deux contacts intérieurs, et que cet in-
ftant du milieu du pafflage déduit de l'une et de autre combi-
naifon reftera toujours abfolument le méme, qu’on fuppof la
planete entource d’une atmofphére ou non. Il eft évident qu’a
plus forte raifon le milieu du paflage déduit de la combinaifon
des deux obfervations du centre de la planete fur la bord du
foleil ne fera point altéré par l’effet dune atmofphére, puif-
quelle n’influe pas méme fur chacune de ces deux obfervations
{éparement, Enfuite j’ai encore fait voir que dans la fuppofi-
tion d'une atmofphére autour de la planéte qui pafle fur le
difque du foleil, le milieu du paflage déduit de la combinaifon
de l’obfervation du contaé& extérieur de entrée avec celle du
contact intérieur de la: fortie, doit arriver plus tard; et le mi-
lieu du paffage donné par la combinaifon du contact intérieur de
Ventrée avec le contact exterieur de la fortie, doit arriver pré-
eifement de la méme quantité plutdt que le milieu du paflage
conclu par la combinaifon des deux contacts intérieurs, ou par
celle des deux contacts extérieurs, ou, ce qui revient encore au
méme, que le milieu du paflage que donneraient indiftinCe-
ment toutes les obfervations des contacts combinées comme on
voudra, fi Ja‘planéte n’avait point d’atmofphere, » La difference
Ua ou
324 Obfersvatiais du’ PF. Paffege des Me rcure 4
_ ou la quantité, > dont le milieu du paflage elt trouvé. git edn
ou plutét, fera effet de!’ viens de Ja planete fur le milieu —
du paflage. mn fii cee a ate. i ie us q
12, En conféquence de ces principes j'ai donc: fait encore
deux combinations pour en déduire le milieu du paflage, et jai
trouvé que la combinaifon du contact extérieur de entrée avec
ie contaé intérieur de la fortie donne.cet inftant a 3h. 40’ 137,65
celle du contact interieur de Pentrée avec le contact extérieur de
la fortie le donne a 3 h. 39’.20%,8. Or on a vu (art. 7.) que le
milieu du paflage, {elon la combinaifon des deux conta&s ine
térieurs et celle des deux. contaéts extérieurs eft arrivé A
3h. 39’ 47’,2, quantité qui fe trouve entre les deux précedentes.
et exactement 4 égales diftances de Pune et de Pautre, favoir de:
26,4. Il eft donc évident que l’effet de l’atmofphére de Mer= |
cure dans ce paflage-ci a été 26,4 de tems fur le miliew du
paflage, en faifant abftraction de toute autre caufe qui peut avoir
uelque influence fur les obfervations des contaéts.
13. Mais ces 26’’,4ne peuvent provenir que-de trois caufes : ou
de l’inexaétitude des obfervations, ou d’une erreur fur lesdiamétres.
du foleil et de Mercure employés dans les calculs, ou de la réfrae-
tion des rayons folaires dans l’atmofphére de Mercure ;. ainfi que
je ’'ai demontré dans mon petit Traité fur les Paflages de Venus et
de Mercure, et olij’arrive, apres un examen rigoureux de toutes les
hypothefes poffibles, a cette equation générale A=a+ Bay +65
dans laquelle A eft la quantite déterminée par les combinaifons
des obfervations, comme ici les 26,4, et par conféquent con
nue; a (, y, €, la part qui en appartient refpectivement a
Vatmofphere de la planete, 4 lerreur de fon diametre, a celle
du foleil et a erreur de l’obfervation. Je ferairemarquer feule-
ment au fujet de cette formule qu'il n’y a que J’erreur fur le
diamétre de la planéte dont J’effet @ pourrait quelquefois entrer
dans
soo par Me jo W. Warnore . 2325
dans le valeur de A comme quantité négative, mais alors, loin
-dé nuire a opinion d’attribuer cet’ effet, qui eft ict de 26,45 a
Yatmofphére de la planete, elle la favoriferait piutot... Quant
a Perreur fur le diamétre du foleil,,.fon influence peut .étre re-
gardee comme nulle dans tous les cas, c’eft a-dire » peut tou-
jours étre regardé comme zéro,,a moins que erreur fur le dia-
métre du foleil ne foit-trés confidérable, et c’eft un des avan-
tages de ma méthode pour déterminer la valeur,de A. Or.la
probabilite ferait en faveur des obfervations,..puifqu’elles don-
nent, ce qui eft. conforme,a Ja théorie, le méme intervalle de
tems entre les deux contacts de entrée qu’entre les deux con-
tacts de la fortie, ainfi Pon aurait ici exo. . Quant aux deux
autres caufes, il.n’en eft pas de méme, puifqu’il eft évident par
da formule générale qu’une méme quantitée confidérée comme
erreur fur les diametres, ou comme réfraction des rayons folaires
dans l’atmofphére, de Mercure, eft capable de. produire exacte-
ment le méme effet. Mais comme il eft trés probable que les
trois caufes 4 la fois peuvent avoir concouru a produire ces
26,4=A, et. qu'il eft abfolument impoflible, d’aprés ma,mé-
thode comme d’aprés toute autre, de déméler les effets pour
_affigner a chaque caufe la part qui lui appartient dans la valeur
de a, le probléme reftera indéterminé a cet égard,. par confé-
quent fi l’on ne veut admettre qu'une feule caufe, on, fera libre
de fe décider pour l’une,ou pour l'autre; or la queftion n’étant
plus alors qu’une affaire d’opinion, le choix doit tomber nécef=
fairement fur la caufe qui eft Ia moins connue, et dont nous ne
pouvons pas raifonnablement contefter l’exiftence, On peut done
fort bien attribuer cet effet,a Vatmofphere. de Mercure fans
craindre de.fe tromper beaucoup. II s’en fuit donc qu’em re=
gardant ces 26”,4 fimplement comme effet de l’atmofphere de
Mercure, la quantité, qui en ré{ulterait pour Vinflexion on la
réfraCtion
326 | Objerwations du Paffage de Mercure ‘.
‘réfradtion réelle de cette atmofphere, nous affurerait au moiiis~
d’une-efpece de limite qu’elle ne furpaflerait j jamais ou du moins
trés-rarement, puifque: V’inflexion des rayons folaires, & ellé- :
feule, ne peut égaler la fomme des trois caufes “dont elle fait
iia que dans: si Milan particuliére des deux autres égales | :
A zéro. -Cette maniére d’envifager le probléme me donnera du
moins une connaifiance approchee de la valeur de la réfraétion de
Yatmofphére de Mercure, dont je n’aurais fans cette recherche —
abfolument aucune idée. Or il me femble qu'il vaut mieux
acquérir une connaiflance imparfaite que de refter — Pigno-
rance abfolue.
14. La quantité de cet effet, quel qu’il foit, étant done con-
nue, j’ai cherché a concilier les deux valeurs de la plus courte
diftance des centres trouvées par les contaéts intérieurs et ex-
térieurs, et pour cet effet je me fuis propofé ce probléme qui doit
sen fuivre naturellement, puifque la valeur de y peut toujours
étre regardéé comme zéro: Determiner le diamétre du foleil, celui
de Mercure étant connu par obfervation, tel que la durée donnée par
les contacts extérieurs et la durée des contaéts intérieurs faffent
trouver, <’une et l'autre, la méme quantité pour valeur de la plus
courte diftance des centres. Ce probleme etant refolu en nom-
mant a, la demi-durée entre les contatts exterieurs, 4 celle des
contacts intérieurs, @ le diametre de Mercure, x la difference
des demi-diamétres de Mercure et du foleil) y la plus courte
bP 3? .
diftance des centres cherchée, je trouve a et y=
At nkeeatty?
a ( free eer formules qui étant’ évaluées aprés avoir cons
venablement corrigé des 26,74 chaque obfervation des quatre
contacts, et augmente la durée des contacts extérieurs de ces
6” dont j’ai parlé ci-devant, me gone ES 967” 104, valeur plus
7 "petite
— far M. J. W. Wattor... 327.
petite de 9’ ad que celle que javais foppelte. dans. mes. calculs,
et y= 15'45",24 plus grande de 0,1 que. celle qui m’a été,
donnée par la combinaifon des deux contacts intérieurs; ainfitous.
les réfultats trouvés par cette combinaifon n’auront befoin qd au-
cune correction, et je les adopterai, comme étant les meilleurs,
tels quils font rapportés dans Ja table ci- -deffs art. ey in
15, En fuppofant donc que les 26’’,4 foient produites: par.
Vatmofphére de Mercure, je trouve 0”276 pour, la réfraction,
horizontile de cette atmofphere. Les) obfervations du patlage;
de, Venus en 1 769 tn’ayant annoncé un effet femblable d’ environ.
874 g” de tems, je trouve fa refraction horizontale d environ
0’’205 qui n’eft qu "A peu prés les deux tiers de celle de Mercure.
CON CL, U.S TOON,
16. Quelque peu de confiance que j’attache a ces réfultats, et
quelque {oit opinion que jadopte pour choifir entre les caufes
qui peuvent produire l’effet en queftion,. je crois du moins pou-
voir conclure avec certitude, ce gue je f’étais principalement
prepols de prouver dans ce Mémoire, quesles’ obfervations dont
i s’agit ici, malgré le degré d’incertitude gu ‘on. puite leur fup-
pofer, indiquent clairement exiftence dun, effet femblable a
celui-d’une atmofphére qui. environnerait lay anéte et que cet
effet, foit qu'il provienne effectivement de cette “atmofphere, ou
dune erreur fur le diamétre de. la ‘planete, ou d’une erreur dans
les obfervations, ou qu'il foit. le réfultat de laétion fimultanée
des trois caufes réunies, il fe fait Lentir evidemment dans toutes
les obfervations des paflages de Venus et de Mercure, du moins.
dans toutes celles que j'ai calculées. Par conféquent l’influence
de ces caufes qui altérent les obfervations d’une maniere fi fen-
fible me parait, fous tous les points de vue, mériter l’attention
des aftronomes ; et je fuis trés perfuadé que faute d’y avoir eu
égard
328 —- Obfervations du Paffage de Mercure, Gc. -.
égard dans la comparaifon des obfervations du paflage de Venus!
pour en déduire Ja parallaxe du foleil, bien des’ aftronomes fe="
raient dans le cas de recommencer leur calcul. Heureufement”
je-n’ai pas ce reproche & me faire; car j’ai conftamment évité~
avec le plus grand foin effet dune atmofphére autour de Venus”
en choififfant les‘obfervations pour en faire la comparaifon de’
maniére que l’effet'de cette atmofphére, qu'il ait exifté ou non,
fe trouvait toujours réduit a zéro, C’eft ainfi que dans mon
Mémoire fur le paflage de Venus en 1769 j'ai fixé a 8,7 la pa-
rallaxe horizontale du foleil dans fes moyennes diftances a la
terre, eT
{ 329 J
XXV. Thoughts on the conffituent Parts of Water and of De-
phlogifticated Air ; with an Account of fome Experiments on
ye Subjed. In a Letter from Mr. James Watt, Engineer,
to Mr. De Luc, F. RS
Read April 29, 1784.
rigger Scie eaeemenene nee
N compliance! with your defire, I fend you an account of the
hypothefis I have ventured to form on the probable caufes
of the produétion ef ‘water from the deflagration of a mixture
of dephlogifticated and inflammable aS) in fome of our friend
Dr. Priestiey’s experiments.
- I feel much relu€tance to lay my thoughts:on thefe fubjects
before the public in their prefent indigefted ftate, and without
having been able to bring them to the'teft of fuch experiments
as would confirm or refute them; and fhould, therefore, have
delayed the publication of them until thefe experiments had
been made, if you, Sir, and fome other of my philofophical
friends, had not thought them as plaufible as any other conjec-
tures which have been formed on the fubje@; and that though
they fhould not be verified by further experiments, or approved
of by men of {cience in general, they may perhaps merit a
difcuffion, and give rife to.experiments which may throw light
on fo important a fubjec.
I firft thought of this way of folving the ‘oer iasad in
| €ndeavouring to account for an experiment of Dr. PrizstT-
i
Vout. LXXIYV. xX x LEY Sy
a
330 Mr. Watr’s Thoughts on the conftituent
LEy’s, wherein water appeared to be converted into air; and "4
communicated my fentimentsina letter addreffed to him, dated —
April 26, :783*%, with a requeft that he would do me the ©
honour to lay them before the Royal Society ; but as, before he
had an opportunity of doing me that favour, he found, in the |
profecution of his experiments, that the apparent converfion of
water into air, by expofing it to heat in porous earthen veffels,
was not areal tranfmutation, but an exchange of the elaftic
fluid for the liquid, in fome manner not yet accounted for ;
therefore, as my theory was no ways applicable to the explain-
ing thefe experiments, I thought proper to delay its publica-
tion, that I might examine the fubje& more deliberately, which
my other avocations have prevented me from doing to this
time. :
1. It has been known for fome time, that inflammable air
contained much phlogifton; and Dr. Priestiey has found,
by fome experiments made lately, that it ‘ is either wholly
é*‘pure phlogifton, or at leaft that it contains:no appareit.mix-_
“ture of any other matter.” (In my opinion, however, it
contains a {mall quantity of water and much, elementaryi
* This letter Dr. Prizstrey received. at London; and, after. fhewing it! to,
feveral Members of the Royal Society, he delivered it to Sir Josern Banks, they
Prefident, with a requeft that it might be read at fome of the public meetings of,
the Society; but before that could be complied with, the author, having‘heard of
Dry PrrestLey’s nei ‘experiments, begged that the reading might be delayed?
The. letter, therefore; was referved until the 22d of April lait; when, at the!
author’s. requeft, it was. read before the/Society., It has been judged unneceflary to,
print that letter, as the effential parts of it are repeated; almoft verbatim, in,
this letter to M. De Luc; but, to authenticate the date of the author’ s ideas, the
parts of it which are contained in the Pectin letter are marked with double
eommasi i wise i: : e
“Meaty
Parts of Water and of Dephlogifticated Air. 331
heat *.) ‘‘ He found, that by expofing the calces of metals
« to the folar rays, concentrated by a lens, in a veffel contain-
«ing inflammable air only, the calces of the fofter . metals
<*¢ were reduced to their metallic ftate;” and that the inflam-
mable air was abforbed in proportion as they became phlogifti-
cated; and, by continually fupplying the veflel with inflamma-
ble air, as it was abforbed, he found, that out of 101 ounce mea-
fures, which he had put. into the veflel, 99 ounce meafures were
abforbed by the calces, and only two ounce meafures remained,
which, upon examination, he found to be nearly of the fame
quality the whole quantity had been of before the experiment,
and to be ftill capable of deflagrating in conjunction with at-
mofpheric or with dephlogifticated air. Therefore, as fo great a
quantity of inflammable air bad been abforbed by the metallic calces ;
the effect of reducing them to their metalhe fiate bad been produced;
and the fmall remaining portion was full unchanged, at leaf had
fuffered no change which might not be attributed to its original want
of purity; it was reasonable to conclude, that inflammable air muft be
the pure phlogifion, or the matter which reduced the calces to
metals. ;
2. * The fame ingenious philofopher mixed together cer-
‘¢ tain proportions of pure dry dephlogifticated air and of pure
<¢ dry inflammable air in a ftrong glafs veffel, clofely thut,
<¢ and then fet them on fire by means of the eleCtric {park,”
in the fame manner as is done in the inflammable air piftol.
*¢ The firft effect was the appearance of red heat or inflamma-
* Previous to Dr. Priesriey’s making thefe experiments, M. Kirwan had
proved, by very ingenious deductions from other facts, that inflammable air was,
in all probability, the real phlogifton, im an aerial form. Thefe arguments were
perfectly convincing to me; but it feems more proper to reft that part of the
prefent hypothefis onthe direct experiment.
Nx 2 : “¢ tion
332 Mr. Warr’s T boughts on the conflituent
<6 tion im the airs, which was foon followed by the glafS.veflel
<‘ becoming hot» The heat gradually pervaded the glafs, and
<< was diflipated in the circumambient air, and as. the glafs 4
<‘ orew cool, a mift or vifible vapour appeared in it, which
‘¢ was condenfed on the glafs in the form of moiture or dew *.
“¢ When the glafs was cooled to the temperature of the atmo=
«¢ fphere, if the vetlel was opened with its mouth immerfed in
«¢ water or mercury, fo much of thefe liquids entered, as was
« fufficient to fill the glafs within about 2 dth part of its.
«* whole contents; and cine {mall refiduum may fafely be con-
“< cluded to have been occafioned by fome impurity in one op
“© both kinds of air. ‘The moifture adhering to the glafs, after
«‘ thefe deflagrations, being wiped off, or fucked up, by a
<< {mall piece of fponge paper, firft carefully weighed, was.
«« found to be exactly, or very nearly, equal: in weight to the
<¢ airs employed.”
‘© In fome experiments, but not im all, a fmall quantity of
‘¢ a footy-like matter was found adhering to the infide cf the
‘ olafs,” the origin of which is not yet inveftigated; but Dr.
PrigesTLey thinks, that it arifes from fome minute grains of
the mercury that was ufed in order to fill the glafs with the
air, which being fuper-phlogifticated by the inflammable air;
aflumed that appearance; but, from whatever caufe it pro-
ceeded, ‘the whole quantity of footy-like matter was too
* {mall to. be an obje& of confideration, particularly as it did
<¢ not occur in all the experiments.”
I am obliged to your friendfhip for the account of the expe=
riments which have been lately made at Paris’on this fubject,,
* TI believe that Mr. CAVENDIsH was the firft who. difcovered that the com-
buftion of dephlogifticated and inflammable air produced moifture on the fides of
the glafs in which they were fired,.
with,
| Parts of Water and of Depblogiflicated Air. cee
with large quantities of thefe two kinds of air, by which the
effential point feems to be clearly proved, that the deflagration cr
union of dephlogitticated and inflammable air, by means of
ignition, produces a quantity of water equal in weight to the
airs; and that the water, thus produced, appeared, by every
teft, tobe pure water. As Iam not furnifhed with any parti-
eulars of the manner of making the experiment, fT can make
no obfervations on it, only that, from the character you give me
of the sentlemen who. made it, there is no reafon. to. doubt of
its being made with all neceffary precautions and accuracy,
which was farther fecured by the large quantities of the two
airs confumed.
3. ** Let us now confider what obvioufly happens in the
“< cafe of the defiagration of the inflammable and dephlogifti-
“cated air. “Vheife two kinds of air unite with violence, they
<< become red-hot, and upon cooling totally difappear. When
*< the veflel is cooled, a quantity of water is found in it equal
“‘ tothe weight of the air employed. ‘This wateras then the
“* only remaining product of the procefs, and water, light, and
“¢ heat, are all the products,”
ter fet free which efeapes our fenfes.
«<< Are we not then authorifed to conclude, that water is come
<< pofed of dephlogifticated air and phlogifton, deprived of part of
<< yheir latent or elementary beat; that depblogifticated or pure air
“< 75 compofed of water deprived of its phlogifion, and united ta
*< elementary beat and light; and that the latter are contained im
<< it in a latent frate, fo as not to be fenfible to the thermometer or
<< to the eye; and if light be only a modification of heat, or @ cir=
<< cumfiance attending it, or a component part of the inflammable
“air, then pure or dephlogifticated air is compofed of water de>
* prived of its phlogiftion and united to elementary heat 2”
4. * It
unlefs there be fome other mat=
334 Mr. Wart’s Thoughts on the conflituent |
4. “It appears, that dephlogifticated. water,” or, vehicle
may be a better natne for the bafis of water and air, the eles
ment you call umor, «has a moré powerful attragtion. iv
‘* phlogiften than i has for latent heat, but that it cannot
<‘ unite with it, at leaft not to the point of faturation, or to (
«¢ the total expulfion of the heat, unlefs it be firft made red~ :
‘¢ hot,” or nearly fo. ‘* The electric fpark heats a portion o
«it red-hot, the attraction between the humor and the phlo- ;
*¢ oifton takes place, and the heat which is let loofe from this
<¢ firft pertion heats a fecond, which operates in a like manner”
‘¢ on the-adjoiing particles, and fo continually until the whole”
<¢is heated ie and decompofed.” Why this attraétion
does not take place to the fame degree in the common tempera-
ture of the atmofphere, is a queftion I am not yet able to
folve; but it appears, that, in fome circumftances, ‘* dephlo-
“« gifticated air can unite, in certain degrees, with phlogifton
** without being changed into water.” Thus Dr. PrizsrLey
has found, that by taking clean filings of iron, which, alone,
produce only inflammable air of the pureft kind, and mercurius
calcinatus per fe, which gives only the pureft dephlogifticated
air, and expofing them to heat, in the fame veflel, he obtained
neither dephlogifticated nor inflammable air, ‘* but in their
‘«« place fixed air.” Yet it is well known, that a,mixture of
dephlogifticated and inflammable air will remain for years in
clofe veffels in the common leat of the atmofphere, without
fuffering any change, the mixture being as capable of deflagras
tion at the end of that time as it was when firft thut up.
Thefe facts the Doctor accounts for, by iuppofing that the two
kinds of air, when formed at the fame time in the fame veffel,
can unite in their wa/cent ftate; but that, when fully formed,
they are incapable of ating upon one another, unlefs they are
Art
Parts of Water and of Dephlogijticated Air. . 995
firft fet in motion by external heat. ‘* Phlogifticated air feems
<< alfo to be another compofition of phlogifion and dephlopifti-
‘cated air;’’ but in what proportions they are united, or by
what means, 1s (ill unknown. It appears to me to be very
probable, that fixed air contains a greater quantity of phlo-
gifton than phlogifticated air does, becaufe it has a greater
{pecific gravity, and becaufe it has more affinity with water.
5. ** For many years I have entertained an opinion, that air
4
n
was a modification of water, which was originally founded
on the facts that in moft cafes, wherein air was actually
«< made,” which fhould be diftinguifhed from thofe wherein it
is only extricated from fubftances containing it in their pores,
or otherwife united to them in the ftate of air, ** the fub-
ow
¢
«* ftances were fuch as were known to contain water as one of
«their conftituent parts, yet no water was obtained in the
’ except what was known to be only loofely con-
“<< procefies,’
neéted with them, fuch as the water of the ecryitallization of
” that the latent
heat contained in {team diuminifhed in proportion as the fen-
fible heat of the water from which it was produced increafed ;
or, in other words, “ that the latent heat of fteam was lefs
© when it was produced under a greater preffure, or ina more
‘odenfe flate, and greater when it was produced under a lefs:
‘“preffure, or in'a lefs denfe ftate; which led me to conclude, ’
falts. <* This opinion arofe from a difcovery,
“< that when a’very great degree of heat was neceflary for the
‘production of the fleam, the latent heat would be wholly
‘changed into fenfible heat; and ‘that, in fuch cafes, the
“ fteam itfelf might fuffer fome remarkable change. IT now
ie abandon this opinion in: fo far as relates to the change of
*“ water into air, as think that may be accounted for.on better
| principles.” |
5 G6, <i
336 Mr. Wartie’s Thoughts on the conftituent
6. ** In every cafe, wherein dephlogifticated air has been’ :
< produced, fubftances have been employed, fome of whofe’
** conftituent parts have a {trong attraction for phlogiften, and,
*¢-as it wouldiappear, a fironger attraction for that fubftance
‘¢ than umor has; they fhould, therefore, dephlogifticate the
«¢ water” or fixed air,-and the Aumor thus fet free fhould unite
to the matter of fire and light and become pure air. Dephlo-
eiftieated air is produced in great abundance from melted nitre.
“¢ The acid of nitre has a greater attraction for phlogifton than
“¢ anyother fubftance is known to have; and.it)1s-alfo certain,
«s that, nitre, befides, its water of .cryftallization, contains a
“* quantity of water as one of its elementary parts, which
s water adheres to the other parts of the nitre;wath a force.
“s fufficient to enable it to fuftain a red heat. When the nitre’
«¢ is melted, or made red-hot, the acid acts upon the water and’
“¢ dephlogifticates it; and the fire fupplies the umor with the?
“¢ due quantity of heat to conftitute it ar, under which forme
“* it immediately iffues. It is not*eafy to tell what becomes of |
«the acid of nitre and phlogifton, which are fuppofed to’be!
‘¢ united,” as they feem to be loft in the procefs. Dr. Priesr-
LEY has lately made fome experiments, with a view to afcer-.
tain this point. He diftilled dephlogifticated air from pure
nitre, in an.earthen retort glazed within and without. He?
employed 2 0z.=960 grains of nitre: the retort was placed in’
an air furnace, and, by means of an intenfe heat, he obtained’
from the nitre in,one experiment 7*7, and in another experi
ment 800 ounce meafures of dephlogifticated air; and he found:
that, upon weighing the retort and nitre before and after the’
procefs, they had fuffered a lofs of. weight equal to’ the weight »
of the air, and to the water of cryftallization of the mitre, but -
nothing more. He remarked, that the air had a pungent:
| {mell,
Parts of Water and of Depblogifticated Air. 339
¥mell, which he could not divett it of by wafhing ; and that -
the water in which the air was received had become flightly
acid. I examined a portion of this water, which he was fo
Kind as to fend me, and found by it that the whole of the re-
ceiving water had contained the acid belonging to 2, drams =
120 grains of nitre. I alfo examined the refiduum and the
retort in which the diftillation had been performed, and found
the refiduum highly alkaline, yet containing a minute quan-
tity of phlogifticated nitrous acid. It had ated confiderably
upon the retort, and had diflolved a part of it, which was dee
pofited in the form of a brownifh powder, when the faline
part was diflolved in water. ‘This earthy powder I have not
yet thoroughly examined, but have no doubt that it princi-
pally confifts of the earth of the retort. This experiment,
and all others tried in earthen veflels, leave us ftill at a lofg
to determine what becomes of the acid and phlogifton. They
feem either to remain mixed with the air, in the form of an
incoercible gas; or to unite with the alkali, or with the earth
of the retort, in fome manner fo as not to be eafily feparated
from them ; or elfe they are imbibed by the retorts themfelves,
which are fufficiently porous to admit of fucha fuppofition.
All that appears to be conclufrve from this experiment 15, that
above one half of the weight of the nitre was obtained in the form
of dephlogifticated air; and that the refiduum fill contained feme
witrous acid united to phlogifion.
7- Finding that the a&tion of the nitre on the retort tended
to prevent any accurate examination of the produdts, I had re-
courfe to combinations of the nitrous acid with earths from
which the dephlogifticated air is obtained with lefs heat than
from nitre itfelf. As thefe proceffes have been particularly de-
eribed by Dr. PRiesTLey, by Mr. ScHEELE, and others, i
You. LXXIV. Vy thall
338 Mr. Warer’s Thoughts on the conflituent 4
fhall not enter into any detail of them; but {hall mention the —
general phenomena which I obferved, and which relate to the ©
iene fubject. :
The earths I ufed were magnefia alba, calcareous caves and —
we a. ee. Pe
minium or the red calx of lead. I diflolved them in the re-
{pedtive experiments i nitrous acid dephlogifticated by boiling, —
and diluted with proper proportions of water. JF made ufe of ©
glafs retorts, coated with clay; and I received the air in glafs
veflels, whofe mouths were immerfed in a glazed éarthen ba- ©
fon, containing the fmalleft quantity of water that’ could be
afed for the purpofe. As foon as the retort was heated a little.
above the heat of boiling water, the folutions began to diftil
watery vapours containmg nitrous acid. Soon after thefe va-
pours ceafed, yellow fumes, and in fome of the cafes dark red
fumes, began to appear in the neck of the retort; and at the ©
fame time there was a production of dephlogifticated air, which
Was greater in quantity from fome of thefe mixtures than from
others, but continued in all of them until the fubftances were
reduced to drynefs. I found, in the receiving water &c. very
nearly the whole of the nitrous acid ufed for their fokution, but
highly phlogifticated, fo as to emit nitrous air by the applica-
tion of heat; and there is reafon to believe, that with more:
precaution the whole might have been obtained. |
8. As the quantity of dephlogifticated: air produced: by thefe
procefles did not form a fufficient part of the whole weight, to”
enable me to judge whether any of the real acid entered intor
the compofition of the air obtained, I ceafed to purfue them)
further, having learned from them the fact, that however much’
the acid and the earths were dephlogifticated before the folution, the
acid always became highly phlogifticated in the procefi..
Paris of Water and of Depblogificated Air. 3
In order to examine whether this phlogiiton was furnithed by
the earths, fome dephlogifticated nitrous acid was diftilled
. from minium till no more acid or air came over. More of the
fame acid was added to the minium as foon as it was cold, and
the diftillation repeated, which produced the fame appearance
of red fumes and dephlogifticated air. This cperation was re-
peated a third time on the fame minium, without any fenfible
variation in the phenomena. The procefs fhould have been
ftill farther repeated, but the retort broke about the end of the
third diftillation, The quantity of minium ufed was 120
grains, and the quantity of nitrous acid added each time was
240 grains, of fuch ftrength that it could diffolve half its
weight of mercury, by means of heat. :
It appears from this experiment, that unlefs minium be fuppofed
to confift principally of phlogifion, the fource of the phlogifion, thus
obtained, was either the nitrous acid itfelf, or the water with
which it was diluted; or elfe that it came through the retort with
the light, for the retort wasin this cafe red-hot before any air was
produced; yet this latter conclufion does not appear very fatif-
factory, when it is confidered, that in the procefs wherein the
earth made ufe of was magnefia, the retort was not red-hot, or
very obicurely fo, in any part of the procefs; and by no means
luminous, when the yellow and red fumes firft made their
appearance.
g. As the principal point in view was to determine whether
any part of the acid entered into the compofition of the air, I
refolved to employ fome fubftance which would part with the
acid in a moderate heat, and alfo give larger quantities of
air than had been obtained in the former procefles. Mer-
cury was thought a proper fubftance for this purpofe. 240
parains of mercury were put into a glafs retort with 480 grains
Viny. 2 of
¢
340 7, Warr’s T, boys on the conflituent
‘of diluted res ici nitrous acid, which was the quan-
tity neceflary to diffolve the whole of the mercury, a gentle:
heat was applied, and as foon as the common air contained in: F
the retort was diffipated, a veflel was placed to-receive the nis 9
trous air proceeding from the folution, which was 16 ounce
meafures. When it had ceafed to give nitrous-air, the neck «|
the retort became hot from the watery fteams of the acid.. Fhe
- gir receiver was taken away, and a common receiver was tinted ¢
on, with a little water i it, to condenfe the vapours, and a
quantity of dilute, but highly phlogifticated, acid was caught _
in the receiver. When the watery vapours. had nearly come
over, and yellow fumes appeared in the neck of the retort,
the common receiver was removed, and the air receiver re- —
placed; about four ounces of very ftrong nitrous air paffed up- .
immediately, the fumes in the retort became 'red, ‘and dephlo- —
gifticated air patied up, which, uniting with the nitrous. air im
the receiver, produced red fumesin ‘the receiver ; “and the two
kinds of air acting upon one another, their bulk was téduced
to ‘half of an ounce meafure. “At this period the fumes dn‘the
retort were of a dark red colour, and dephlopifticated ‘air was
produced very faft. After'a fhort time, fome orange-coloured! |
fublimate ‘appeared im the upper part of ‘the retort, and ex-
tended a httle way along its neck, ‘the red colourof thefames
gradually difappeared, and the neck of the retort becamequite
clear. At the fame time that this happened, {mall lobules of
mercury appeared in the neck of the'retort, ‘and accumulated:
there until they ran down in’drops. The produétion of theair
was now very rapid, and accompanied with much of the white
cloud or powdery matter, which pafled up ‘with the'air intothe
receiver, and mixed with the water, but did‘not diffelve invite.
After giving ‘about 36-ounce “meafures ‘of dephlogifticatediair,.
a
Paris of Water and of Dephlogifticated Air. 341
tt fuddenly ceafed to give any more; and the retort being
cooled, the bulb was found to be quite empty, excepting a
fmail quantity of black powder, which, on being rubbed on
the hand, proved to be moftly running mercury. The orange-
coloured fublimate was wafhed out of the neck of the retort,
and what running mercury was in it was feparated, and added
to that which had run down into the bafon among the water.
The whole fluid mercury, when dried, weighed 218 grains 5
therefore 22 grains remained in the form of fublimate, which,
I believe, would alfo have been reduced if I could have applied
heat in a proper manner to the neck of the retort, as fome of
it, to which heat could be applied, difappeared.
10. The 16 ounce meafures of nitrous air, which had been
produced in the {olution of the mercury, and had remained
confined by water in the receiver, was converted into nitrous
acid by the gradual admiflion of common air, and was taken
up by the water; this water was added to that in the bafon,
swhich had ferved to receive the dephlogifticated air. The
whole quantity was about two. quarts, was very acid to the
tafte, and {parkling with nitrous air. It was immediately put
nto bottles, and well corked, until it had loft the heat gained
an the operation. In order to determine the quantity of acid
in the receiving water and in the fublimate, I diffolved, firft,.
alkali of tartar m water, and filtered the folution. 352 grains
of this alkaline folution. faturated 120 grains of the nitrous.
acid I had employed to diflolve the mercury, and 1395 grains
of the fame alkaline folution faturated the orange-coloured pre-
‘eipitate, and all the acid liquor obtained from the procefs :
therefore we have \the proportion as 352.:,120 251395: 475,
“from which it appears, ‘that all the acid employed. was re-
“coverediagain in the.form.of acid, excepting only five grains ;
a {maller
442 Mr. Warr’s Thousbts on the doe Rivviene™
“a fmaller quantity than what might reafonably be. fuppofed a
be loft in the procefs by the extreme volatility ef the nitrous”
air, In order to afcertain the exa& point of faturation, flips
of paper, flained by the juice of the petals of the fearlet fofe, ‘
were employed, which were the niceft teft I could procure, ©
as litmus will not thew the point of faturation of any liquor
containing much phlogifticated nitrous acid, or even fixed ‘
air, but wail turn red, and fhew it to be acid, when the teft of
thofe leaves, violets, and fome other of the like kind, will turn —
green in the fame liquor, and fhew it to be alkaline. But the
exact point of {aturation of fo dilute a liquor is fo very difficult —
to afcertain, than an error might eafily be committed, not- |
withitanding the attention beftowed upon it. Suppofing this’
experiment to be unexceptionable, the conclufions which may
be drawn from it are very favourable to the hypothefis I endea-
vour to fupport. Thirty-fix ounce meafures of dephlogifiicated
air were obtained, and only five grains of a weak nitrous acid
were loft in the procefi. Two hundred and eighteen grains of
mercury out of two hundred and forty were revived, and all the
dephlogiflicated nitrous acid employed is found to be highly phlogifti=
cated mm the proce/s. It appears, that the nitrous acid does mot
enter into the compofition of dephlogiflicated air; 1¢ feems only to
Serve to abford phlogifion from the watery part of tbe mercurial:
nitre. ¢
11. As this laft procefs proved very tedious and complicated
on account of the necefflity of afcertaining the quantity of acid”
im the receiving water, by means of an alkali which afforded a
double fource of error in the point of faturation, I refolved to’
try the diftillation of dephlogifticated air from cubic nitre im a
glafs veffel, and to draw from it only fuch a quantity of air as
it would yield without a@ing much upon the retort, which
latter
9
4
us
Parts of Water and of Dephlosifticated Air. 343
latter circumftance’ is effentially neceflary to be attended to.
An ounce of the cryftals of mineral alkali were diffolved in
nitrous acid, and.the mixture brought to an exact faturation by
the teft of litmus; 30 ounce meafures of air were diftilled from
it, which, during the latter part of the procefs, was accom-
panied with flightly yellow fumes; the receiving water was
found to be acid, and the refiduum alkaline. he refiduum
being diffolved in the receiving water, the folution was neu-
tral, or very nearly fo, by every teft; for in this cafe litmus.
might be ufed, asthe acid was very flightly phlogifticated. On
adding a few drops of a very dilute nitrous acid, the tefts
fhewed the liquor to be acid.
12. Encouraged by the fuccefs of this experiment, I took
an ounce= 480 grains of pure common nitre, and put it into a
flint-glafs retort, coated, which was placed in a furnace. It
began to give air about the time it became red-hot, and during ©
the latter part of the procefs this air was accompanied with
yellowifh fumes.’ I ftopped the procefs when it had produced,
$0 ounce meafures of air. The receiving water, and parti-
cularly the air, had a ftrong but peculiar {mell of nitrous acid.
The air was well wafhed with the receiving water, but was
not freed from the fmell. The receiving water, which was
50 ounces, was flightly acid, and the refiduum alkaline. I
diffolved the latter in the former, and found the mixture alka-
line. 10 grains of weak nitrous acid were added to. it, which
faturated it, and105 grains of this fpirit of nitre was found to
contain the acid of 60 grains of nitre; therefore the Io grains
contained the acid of 5,7 grains of nitre, which, by Mr. Kir-
WAN’s experiments is equal to two grains of real nitrous acid.
We have, therefore, 34 grains weight of dephlogifucated air
produced, and only two grains of real acid miffing ;, and it is not
certala,
344 Mr. Watt’s Thoughts on the confti tuent :
certain that this quantity was deftroyed, becaufe fome portio
of the glafs of the retort was diffolved by the nitre, and fome
part of the materials employed in making the glafs being alkali, —
we may conclude, that the alkali of ‘the nitre | |
mented by the alkali of that part of the glafs-it haddiffélved. ~
As the glafs cracked into {mall pieces on Cooling, and fome part. ]
of the coating’ adhered firmly to it, the auadtte of the glafs
that was diffolved could not be afcertained. From this experi= .
ment it appears, that if any of the acid of the nitre enters into
the compofition of the dephlogifticated air, it is a very fmall parts
and it rather feems, that the acid, or part of it, unites itfelf fo
firmly to. the phlogifton as to lofe its attraction for water. hoe
13. * The vitriolic falts alfo yield dephlogifticated air ‘by
«¢ heat; and in thefe cafes the dephlogifticated air is always
«attended with a large quantity of vitriolic acid air or ful~ —
<¢ phureous vapour,” even when the falts ufed are not known —
to contain any phlogiftic matter. Mr. ScHEELE mentions his ,
having obtained dephlogifticated air from manganefe diffolved —
in acid of phofphorus, and alfo from the arfenical acid: from.
whence it appears, that thefe acids, or perhaps any acid which
can bear a red heat, can concur to the produétion of dephlo-
gifticated air. dt is neceffary to remark, that no experiments have
been yet publifbed foewing that dephlogifiucated air can be produced
Jrom falts formed by the murtiatic acid. ‘Ihe acids which produce”
falts fuitable for this purpofe, bave all a frong affinity with
phlogifion; and the marine acid has either a very [mall affinity
with it, or elfe is already faturated with it, at leaft fo Eb Satu
rated as not to be able to attract it from the humor.
14, “ The dephlogifticated air obtained from the pure calees”
** of metals may be attributed to the calces themfelves, attratt-
** ing the phlogifton from water which they have imbibed fromy
4 ‘* thes
ee et ee Se é
Parts of Water and of Dephlogifiicated Air, 345
* the atmofphere, or from dephlogifticating the fixed air which
** they are known to contain,”
It is very probable, that the dephlogifticated air extruded from
- growing vegetables may be owing to their dephlogifticating the
water they grow in; but it appears more probable, that the
plants have a power of dephlogifticating the fixed, or phio-
gifticated, air of the atmofphere.
«¢ When dephlogifticated and nitrous air are mixed, the de-
¢ phlogifticated air feizes part of the phlogifton of the nitrous
‘¢ air.” The water contained in the nitrous air, and the other
part of the phlogifton, unite with the nitrous acid, which ther
afflumes a liquid form, or at leaft that of a denfe vapour; “ and
<< that part of the latent heat of the two airs not effential to the
<¢ new combination is fet at liberty *.”
In the combuftion of fulphur the fame thing happens, but
in a greater degree ; for the vitriolic acid, having a much weaker
attraction for phlogifton than air has, abandons it almoft en-
tirely to the latter, which is thereby converted into water, and
in that form attracts the vitriolic acid, and reduces it to a liquid
ftate. ‘The fame reafoning may be applied to the combutftion
~of phofphorus, which is attended with fimilar effects.
* J cannot take upon me todetermine, from any facts which have come to my
knowledge, whether any part of the dephlogifticated air employed in this experi-
ment is turned into fixed air; but I am rather inclined to think that fome part is,
becaufe the quantity of heat, which is feparated by the union of the two airs,
does not feem to be fo great as that which is feparated when the dephlogifticated
air is wholly changed into water: yet fome water appears to be formed, becaufe
when the mixture is made over mercury, the folution of the mercury in the ni-
trous acid affumes a cryftallized form, which, however, may be due to the watery
part of the nitrous air.
Vot. LXXIV. LZ 15.1
Pa Mr. Wat's Thoughts on ibe conflituent :
15. I fhall not make, at prefent, any further deduétions’
from what I myfelf confider ftill in the light of a conjectural’
hypothefis, which I have perhaps dwelt upon too long already.
I fhall only beg your attention to fome general reafoning on the
fubject ; wens however, may poilibly ferve more to fhew the
uncertainty of other fyftems on the conftituent parts of air, than
the certainty of this. Some of thofe fyftems tuppofe dephlo-
gillicated air to be coempofed of an acid and fedachhiaie elfe,
fois fay phlogifton. If an acid enters into the compofition of
it, why does not that acid appear again when the air 1s decom=
pofed, by means of inflammable air and heat?) And why is
the water which is the product of this procefs pure water?
And if an acid forms one of its conftituent parts, why has no+
body been able to detect any ditterence in the dephlogifticated
air, made by the help of different acids, when compared with
one another, or with the air extruded by vegetables? Thefe
airs, of fuch different origins, appear to be exactly the fame.
And if phlogifton be a conftituent part of air, why does it at-
tract phlogifton with fuch avidity ? Some have, on the other
hand, contended that air is compofed of earth, united to acids.
or phlogifton, or to both, or to fome other matter. Here we:
muft aik, what earth it is which is one of the component
parts of air? All earths which will unite with the nitrous or
vitriolic acids, and with fome others, fuch as the phofphoric
and the arfenical acids, will ferve as bafes for the formation
of air, and the air produced from all of them appears by every
teit to be the fame, when freed from accidental impurities..
To this argument it is anfwered, that it is not any particular
{pecies of earth which is the bafis of air, but elementary or fim-
ple earth, which is contained in all of them. ‘If this were’the
/ ? matter
Parts of Water and of Depblogifiscated Air. aa
matter of fact, would not that earth be found after the decom-
pofition of the air?
_, Mr. ScHEELE has formed an Hadas rs on this fubject, in
which he fuppofes heat to be compofed of dephlogifticated air
united to phlogifton, and that this combination is fufficiently
fubtile to pats through glafs veffels. He affirms, that the ni-
trous and other acids, when in an ignited ftafe, attract the
phlegifton from the heat, and fet the dephlogitticated air at h-
berty ; but he does not feem to have been more fuccefsful than
mytelf, i in explaining what becomes of the acid of nitre and
phlogifton i in the cafe of the decompofition of nitre by heat.
And fince we know, from the late experiments, that water is a
compofition of air, or more properly, Aumor and phlogifton, his
whole theory muft fall to the ground, unlefs that faét be other-
wife accounted for, which it does not feem eafy to do.
16. To return to the experiment of the deflagration of
dephlogifticated and inflammable air, ‘it appears from the
<< two. airs becoming red-hot on their union, that the quantity:
e ¢ of heat contained in one or both of them, is much greater
*¢ than that contained in {team ; becaufe, for the firft moments
= after the explofion, the water depofited by the air remains in
ac ‘ the form of fteam, and confequently retains the latent heat
“ due to that modification of water. This matter may be eafily
AS ‘ examined by firing t the mixture of dephlogifticated and inflam-
ce mable air in a velfel immerfed in another veflel containing a
ec given quantity of water of a known heat, and after the vefiel
“¢ in which the deflagration i is performed is come to the fame
4 temperature with the water in which it is immerfed, by ex-
“ amining how much heat that water has gained, which being
«¢ divided by the quantity of water produced by the decom-
zs _pofition of the aur, will give the whole qua: ntity of elemen-
, Voc ‘etary
348 Mr. Watt's Thoughts on the conftituent
és tary or latent heat which that water had ‘contained, both aaa
‘air and as {team 3; and if from that quantity we deduét the .
i, latent heat of the fteam, the remainder will be the latent or.
‘¢ elementary heat contained more in air than in fteam.” This ©
experiment may be made more compleatly by means of the ex-
cellent apparatus which Mefl. Lavorsier and De La Prace
have contrived for fimilar purpofes.
Until direct experiments- are made, we may conclude, from:
thofe which have been made by the gentlemen juft named, on
the decompofitions of air by burning phofphorus and char-
coal, that the heat extricated during the combuftion of inflam-
mable and dephlogifticated air is much greater than it appears
to be; for they found that one Paris ounce (= 576 Parifian
grains) of dephlogifticated air, when decompofed by burning
phofphorus, melted 68,634 ounces of ice; andas, according to
another of their experiments, ice, upon being melted, abforbs
135° of heat, by FAHRENHEIT’s {cale, each ounce of air gave
out 68,634 x 135°=9265°,590; that is to fay, a quantity of —
heat which would have heated an ounce of water, or any other
matter which has the fame capacity for receiving heat as water
has, from 32° to 9265%°: a furprifing quantity! (It is to be
underftood, that all the latent heats mentioned herein are com-_
pared with the capacity of water). And when an ounce of —
dephlogifticated air was changed into fixed air, by burning }
charcoal, or by the breathing of animals, it melted 29,547 oz. 4
of ice; confequently we have 29,547 x 135°= 3988°,845. the 3
quantity of heat which an ounce ef dephlogifticated air lofes” 4
when it is changed into fixed air. By the heat extricated dur-
ing the detonation of one ounce of nitre with one ounce of
fulphur, 32 ounces of ice were melted ; and, by the experiment
1 haye mentioned of Dr, PriesTLEy’s (6), it appears that
nitre
SS)
Paris of Water and of Dephlogifticated Abr. 349
nitre ‘can. produce one half of its weight of dephlogifticated-air.
When the nitre and fulphur are kindled, the dephlogifticated
air of the nitre unites with the phlogifton of the fulphur, and_
fets its acid free, which immediately unites to the alkali of the
nitre, and produces vitriolated tartar. The dephlogifticated air,
united to the phlogifton, is turned into water, part of which is
abforbed by the vitriolated tartar, and part is diffipated in’ the
form of vapours, or unites to the nitrous air, or other alr, pro-
duced in the proce(s. ,
- As half an ounce of dephlogifticated air is, in this pkodetes
united by inflammation toa quantity of phlogifton fufficient to
faturate it, and no fixed air is produced, it fhould melt:a quan-
tity of ice equal to the half of what was melted by the com-
bination of an ounce of air with phlogifton in burning :phof-
| phorus; that is, it fhould melt 34,317 ounces of ice; and we
find, by Meff. Lavoisier and De La PLAcek’s experiment,
that it actually melted 32 ounces of ice: the {mall difference
“may be accounted for by fuppofing, that the heat produced by
the combuftion might not be quite fo great as that Dr.
PrigsTLEY employed in his experiment; or that the nitre
might be lef pure, and confequently not fo much air formed.
The two facts, however, agree near enough to permit us to
conclude, that dephlogifticated air, in uniting to the phlogifion
of fulphur, produces as much heat as it does in ae with the
phlogifton of phofphorus.
17s According to Dr. PRiesTLEY’s sapere dephlogif-
ticated air unites compleatly with about twice its bulk of the
inflammable air from metals. The inflammable air being fup-
\pofed to be wholly phlogifton, and being =; of the weight
‘ofan equal bulk of dephlogifticated air, and being double in
‘quantity, will be a of the weight of the dephlogifticated air
pe
350 Mr, War's Thoughts on. the confistuent
it unites with. ‘Therefore one ounce (576. grains) of deph
gifticated air, will require 120 grains of inflammable air, or
phlogifton, to convert it into water.’ And fuppofing the heat.
extricated by the union of dephlogitticated and inflammable air
to be equal to that extricated by the burning of phofphorus,
we fhall find, thatthe union of 120 grains of inflammable air
with 576 eras of! wisphinalunaie ails extricates 9265° of
heat. - 2 : a
18. Inthe eupcumere on the deflagration a nitre wens ca
coal, by Mef{; Lavotster and De La PLacE, an ounce of
nitre and one third of an ounce .of charcoal. melted twelve
ounces of ice. Suppoting the ounce of nitre to have produced
half an ounce of dephlogifticated air, it ought to have confum=,
ed.o,1507 ounces of charcoal, and fhould have melted 1 45773)
ounces. of ice ;) and I fuppofe it: fell fhort of, its effectby,. the
heat not being sacs intenfe to decompofe the: nitre pers,
fedtly. ( , . fhe thaedt
19. By the above eenidesineut $ experiment an ounce of char coall
required for its combuftion 3,3167 ounces of dephlogifticated air,,
and produced 3,6715 ounces of fixed aij; therefore there wasy
united to’each ounce of air; when changed into fixed air, 61,5,
grains of phlogifton, and 3988? of heat were extracted. Ji ap-"
pears by thefe facts, that the union of phlogifion, in different propar-,
tions, with dephlogifticated air, does not extricate proportional quar,
tities of heat. For the addition of 61,5 grains produces 3988?
and thé union of 120 grains produces 9265°. This difference
may arife from a miftake!in {uppofing the fpecific gravity, of the,
inflammable air Dr. Parestrrey employed to have beenonly-£%
of that of dephlogifticated air ;, for, if it be fuppofed that its
{pécific gravity was a little more.than 4 of that) of, the , de=,,
phlogifticated air, then: equal additions of phlogifton.. would ,
” havell
Paris of Water and of Dephlogifiicated Air. 351
have produced equal quantities of heat*: this matter fhould
therefore be. put to the teft of experiment, by deflagrating de-
phlogifticated air with inflammable air of. a known. {pecific
gravity, or by finding how much dephlogifticated air is necef-
fary for the combuftion of an ounce of {ulphur, the quantity
of phlogifton in which has been accurately determined by Mr.
Kirwan; or by finding the quantity of phlogifton in’ phof-
phorus, the quantity of dephlogifticated air neceffary for its de-
compofition being known from Mefi.. Lavoisier and De 1a
PLAcE’s experiments.
On confidering thefe latter gentlemen’s experiments on the
combuftion of charcoal, a difficulty arifes, to know what be-
came of the remainder of the ounce of charcoal; for the
dephlogifticated air, in becoming fixed air, gained only the
weight of 0,3548, or about + of an ounces; about 2 of
an ounce are therefore unaccounted for. The weight of
the afhes of an ounce of. charcoal. is very inconfiderable ; + ands
by fome experiments of Dr. Prisstiey’s, charcoal, when freed
from fixed air, and other air which it imbibes from the atmof-
phere, is almoft wholly convertible into phlogifton. The. caufe
of this apparent lofs of matter, 1 doubt not, thefe gentlemen
ean explain fatisfactorily, and very probably in fuch a manner
as will throw other lights on the fubjecé.
?
* Orit may arife irom my being miftaken, in fuppofing that the {ame quantity”
of heat is difengaged by the union of dephlogifticated air with phiogifton, “in the
form of inflammable air, as is by its union with the phlogifton of phofphorus or,
fulphur ; and there appears to be fome reafon why there fhould not; becaufe in
thefe latter cafes the water, being united to the acids, cannot retain fo much ele-
mentary heat asit can do when left in the form of pure water, which is the cafe
| when the inflammable air is wled.
tt
Pa “tire
tk :
a)
! a
352 Mr. Wart's Thoughts on the confituent —
It is alfo worthy of enquiry, whether all the amazing quan=
tity of heat let loofe in thefe experiments was contained in the
dephlogifticated air; or whether the greateft portion of it was
not contained in the phlogifton or inflammable air. If it was
all contained in the dephlogifticated air, ‘“ the general rule is not
‘¢ faét, that elafit fluids are enlarged in their dimenfions in propor=
‘¢ tion to the quantity of heat they contain;” becaufe then, inflam-
mable air, which is ten times the bulk of dephlogifticated air,
muft be fuppofed to contain no heat at all; ‘* and it is known,
** from fome experiments of my friend Dr. Bracx’s, and fome
“¢ of my own, that the fteam of boiling water, whofe iatent
‘*¢ and fenfible heat are only 1100", reckoning from 60°, or tem-
‘* perate, is more than twice the bulk of an equal weight of
‘* dephlogifticated air.” It feems, however, reafonable to fup=
pofe, that the greater quantity of heat fhould be contained in
the rarer fluid.
It may be alledged, that in proportion to the quantity of
phlogifton that is contained in any fluid, the quantity of heat
isleffened. But if we reafon by analogy, the attraction of the
particles of matter to one another in other cafes is increafed
by phlogifton, and ** bodies are thereby rendered fpecifically
¢¢ heavier; and we know of no other fubftance befides heat
which can be fuppofed to feparate the particles of inflammable
air, and to endow it with fo very great an elaftic power, and
fo {mall a fpecific gravity. On the other hand, if a great
quantity of elementary heat be allowed to be contained in in=
flammable air, on account of its bulk, the fame reafoning can-
not hold good in refpe& to the phlogifton of phofphorus, ful-
phur, charcoal, &c. But all thefe fubftances contain other
matters befides phlogifton and heat. The acids in the fulphur
and
Parts of Water and of Dephlogifiicated Air, 355
and phofphorus, and the alkali and earth in charcoal, may at-
tract the pklogifton fo powerfully that the heat they contain
may not be able to overcome the adhefion of their particles,
until, by the effect of external heat, they are once removed te
fuch a diftance from one another as to be out of the {phere of
that kind of attraction *. . |
If it be found to be a conftant fact, that equal additions of
phlogifton to dephlogifticated air do not extricate equal quan-
tities of heat, that may afford the means of finding the quanti-
ties of heat contained in phlogifton and dephlogifticated air re-
fpectively, and folve the problem. .
. Many other ideas on thefe fubjects ete themfelves; but
J am not bold enough to trouble you, or the public, with any
{peculations, but fuch as I think are fupported. by uncontro-
verted facts. |
I muft therefore bring this long letter to a conclufion, and
leave to others the future profecution of a fubje&t which, how-
ever engaging, my neceffary avocations prevent me from pur-
fuing. I cannot however conclude, without acknowledging my
obligations to Dr. PRIESTLEY, who has given me every infor-
mation and affiftance in his power, in the courfe of my enqui-
ties, with that candour and liberality of fenti iment which diftin-
guith his charaéter.
I return you my thanks for the obliging attention you have
paid to this hypothefis; and remain, with much efteem, &c,
JAMES WATT.
* On the whole, this queftion feems to involve fo many difficulties, that it cannot
_ be cleared up without many new experiments.
Awe
Vor, LXXIV. Aaa
[354 a ible
XXVI. Sequel to the Thoughts on the conflituent Parts of Wated
and Dephlogifiicated Air. In a fubfequent Letter from Mr.
James Watt, Eagincer, te Mr. De'Lucy B. Ros: :
Read May 6, 1784.
Fi : Birmingharsy
pt AR oS TR, April 30, 1754.
N re-confidering the fubje& of my letter to you of the
26th of November laft, I think it neceflary to. refume
the fubject, in order to mention fome neceflary cautions tothofe
who may chufe to repeat the experiments mentioned there, and
to point out fome circumftances that may caufe variations in
the refults.
In experiments where the dephlogifticated air is to be dif-
tilled from common or cubic nitre, thefe falts thould be puri-
fied as perfectly as poflible, both from other falts and from
phlogiftic matter of any kind; otherwife they will produce
fome nitrous air, or yellow fumes, which will leflen the quan-
tity, and, perhaps, debafe the quality of the dephlogrfticated
air. If the nitre is perfectly pure, no yellow fumes are per-
ceptible, until the alkaline part begins to aét upon the glafs of
the retort, and even then they are very flightly yellow.
When earthen retorts are ufed, and a large quantity of air is
drawn from the nitre, it aéts very much upon the retort, dif-
folves a great part of it, and becomes very alkaline, retaining
only a {mall part of its acid, at leaft only a {mall part which
6 can
Sequel to Mr. Watt's Thoughts, &c 2e%
¢an be made appear in any of the known forms of that acid
and unlefs retorts can be obtained of a true apyrous and com-
pact porcelain, I fhould prefer glafs retorts, properly coated,
for making experiments for the prefent purpofe.
In fome of my experiments the nitre was left in the retort
placed in a furnace, fo that it took an hour or more to cool:
In thefe cafes there was always a deficience of the acid part;
which feemed, from fome appeafances on the coating, either
to have penetrated the hot and foft glafs, by pafling from par-
ticle to particle, or to have efcaped by {mall cracks which hap-
pened in the retort during the cooling. ‘There was the leaft
deficience of the acid when the diftillation was performed as
quickly as was practicable, and the retort was removed from
the fire immediately after the operation was finifhed. In order
to fhorten the duration of the experiment, and confequently to
lefflen the action of the nitre on the retort, it is advifable not
to diftil above 56 ounce meafures of dephlogifticated air from
an ounce of nitre. The experiment has fucceeded beft when
the retort was placed in a charcoal fire in a chafing-dith or
open furnace; becaufe it is eafy in that cafe to ftop the opera-
tion, and to withdraw the retort at the proper period.
When the dephlogifticated air is diftilled from the nitre of
mercury, the folution fhould be performed in the retort itfelf,
and the nitrous air produced by the folution fhould be caught
in a proper receiver, and decormpofed by the gradual admiffion
of common ait through water; and the water, which thus be-
comes impregnated with the acid of the nitrous air, fhould be
added after the procefs to the water through which the dephlo-
gifticated air has pafled. When the folution ceafes to give any
more nitrous air, the point of the tube of the retort fhould be
raifed out of the water; otherwife, by the condenfation of the
Aaa2 watery
346 | ‘Sequel fo Mr. Watr’s Thoughis
watery and acid vapours which follow, a partial exhauftion will
take place, and the receiving water will rife up into the retort’ —
and break it, or at leaft fpoil the experiment. A common re- |
ceiver, fuch as is ufed in diftilling {pirit of nitre, thould be
applied, with a little water in it, toreceive the acid fteam; and
_ it thould be kept as cool as can conveniently be done, as thefe
fumes are very volatile. ‘This receiver fhould remain as lone —
as the fumes are colourlefs; but when they appear, in the
neck of the retort, of a yellow colour, it is a mark that the
mereurial nitre will immediately produce dephlogifticated air >
the receiver fhould then be withdrawn, and an apparatus placed
to receive the alr. The reft of the procels has Sia fufficiently
explained in my former letter.
The phlogifticated nitrous acid, faturated by an alkali, will
not cryftallize; and, if expofed to evaporation, even in’ the’
heat of the air, will become alkaline again, which fhews the
weaknefs of its affinity with alkalies when diffolvedin water * ;
a farther proof of which is, that it is expelled from them by
all the acids, even by vinegar (which fact has been obferved
by Mr. ScHeExe). I have obferved, that litmus is no teft of
the faturation of this acid by alkalies; for the infufion of lit-
mus added to fuch a mixture will turn red, when the liquor
appears to be highly alkaline, by its turning the infufions of
violets, rofe leaves, and moft other red juices, green. This
does not proceed from the infufion of litmus being more fenfi-
ble to the prefence of acids than other tefts; for I have lately
difcovered a teft liquor (the preparation of which I mean to
publifh foon) which is more fenfible to the prefence of acids
* You have informed me, that Mr. Cavenptsu has alfo obferved this fact 5
and that he has mentioned it in a paper lately read before the Royal Society 5, but I
had obferved the fact previous to my knowledge of his paper.
than
on Water and Dephlogiflicated Air. pay,
than litmus is; but which turns green in the fame folution of
phlogifticated nitre that turns litmus red.
_ ‘The unavoidable little accidents which have attended thefe
experiments, and which tend to render their refults dubious,.
have prevented me from relying on them as full proofs of the.
pofition that no acid enters into the compofition of dephlogifti-
cated air; though they give great probability to the fuppofi-
tion. Ihave, therefore, explained the whole of the hypothefis
and experiments with the diffidence which ought to accompany
every attempt to account for the phenomena of nature on
other principles than thofe which are commonly received by
philofophers in general. And in purfuance of the fame mo-
tives it is proper to mention, that the alkali employed to fatu-
rate the phlogifticated nitrous acid, was always that of tartar
which is partly mild; and I have not examined whether highly
phlogifticated nitrous acid can perfectly expel fixed air from an
alkah, though I know no fact which proves the contrary. It
fhould alfo be examined, whether the fame quantity of real
nitrous acid is requifite to faturate a given quantity of alkali,
when the acid is phlogifticated, as is neceflary when it is de+
phlogifticated.
As I am informed that you-have done me the honour to com+
municate my former letter on this fubject to the Royal Society,
I thall’be obliged to you to do me the fame favour in refpect te.
he oe letter, if you judge that it merits it..
Tremain, &c.
JAMES WATT.
nek Aaa eo ab RSE eel
el
SS
Y
|
ftrong Fire, defcribed in Vol. LXXII. of the Philfo ofo phical
Tranfactions, with the common Mercurial Ones. B yy Mr. Jane
Wedgwood, F. R. S. Potter to Her Majefy.
AXVIL. An Antemps to compare and poems the Ti ore jor
Read May 13,1784.
HIS thermometer, which I had the honour of laying
before the Royal Society in May 1782, has now been
found, from extenfive experience, both in my manufactories—
and experimental enquiries, to anfwer the expectations I had
conceived of it as a meafure of all degrees of common fire ©
above ignition: but at prefent it {tands in a detached ftate, not
connected with any other, as it does not begin to take place till
the heat is too great to be meafured or fupported by mercurial
ones. 4
What is now therefore wanting, to give us clear ideas of
the value of its degrees, is, to connect it with one which long
ufe has rendered familiar to us; fo that if the fcale of the
common thermometer be continued indefinitely upwards as a
ftandard, the divifions of mine may be reduced to that feale,
and we may thus have the whole range of the degrees of heat
brought into one uniform feries, exprefled in one language, and
comparable in every part, from the loweft that have hitherto
been produced by any artificial freezing mixtures, up to the
higheft that can be obtained in our furnaces, or that the mate~
rials of our furnaces and veflels ean fupport. '
The
Mr. Wepewoon’s Method of conneéting, &c. 359:
"The hope of attaining this defirable and important object
gave rife to the expertments which I have now the honour of
communicating. How far I may have fucceeded, or whether
the means employed were adequate to the end propofed, is,
with ail deference, fubmitted to this illuftrious Society.
This attempt is founded upon the conftruction and: applica-
tion of an intermediate meafure, which takes in both the heats.
that are meafurable by the mercurial thermometer, and a fuffi-
cient number of thofe that come within the province of mine:
to connect the two together; the manner of doing which will
be apparent from the three firft fgures (tab. XEV.); wherein F’
reprefents FAHRENHEIT’s thermometer, with a continuation of
the fcale; W my thermometer; and M the intermediate mea-
fure divided into any number of equal parts at pleafure.
For if the heat of boiling water, or 212 degrees. of Fan-
RENHEIT, be communicated to M, and its meafure upon Mi’
matked, as at a; and if the heat of boiling mercury, or 600°
of FAHRENHEIT, be alfo communicated to M, and marked:
as at 4; itis plain, that the number of degrees upon M be-
tween @ and 4 will be equal to the interval between. 212 and:
600, that is, to 388° upon FAHRENHEIT.
In like manner, upon expofing M to two different heats.
above ignition along with my thermometer pieces, if a certain
degree of my fcale be found to correfpond with the point d,.
and another degree of mine with the point c; then. the inter-
val between thofe two degrees upon mine muft be equal to the:
interval de; and how many of Fanrenuett’s that interval is
equivalent to will be known from the preceding comparifon.
Thus we can find the number of FAHRENHEIT’s degrees con-
tained in any given extent of mine, and the degree of Fau-
RENHEIT’s with which a given point of mine coincides >
whence
360 Mr, Wspewoon’s Method of conneéting °°
avhence either, fcale is eafily reducible to,the other through
their whole range, whether we fuppofe FAHRENHEIT’s contix |
nued upwards, or mine downwards. | mt 3
_ For obtaming the intermediate thermometer different means
were thought of ; but the only principle which, upon attentive
confideration, afforded any profpect of fuccefs, was the expan-
fion of metals. ‘Uhis therefore was adopted, and among dif-
ferent methods of meafuring that expanfion, which either oc-
curred to myfelf, or which I can find to have been praétifed by
others, there is no one which promifes either fo great accuracy,
or convenience in ufe, as a gage like that by which the ther-
‘mometer pieces are meafured: the utility of this gage had now
been confirmed to me by experience, and the machines and
long rods, which have been employed for meafuring expanfions
on other occafions, were abfolutely inadmiffible here, on ac-
count of the infuperable difficulties of performing nice opera-
tions of this kind in a red heat, and of communicating a per-
fectly equal heat through any confiderable extent. |
To give a clearer idea of this fpecies of gage, which, fas
ple as it is, I am informed has been mifunderftood by fome of
the readers of my former paper, a reprefentation of one ufed
on the prefent occafion is annexed in fig. 4. where ABCD is a
{mooth: flat plate; and EF and GH two rulers or flat pieces, a
quarter of an inch thick, fixed flat upon the plate, with the
fides that are towards one another made perfeétly true, a little:
further afunder at one end EG than at the other end FH; thus”
they include between them a long converging canal, which :
divided on one fide into.a number of {mall equal parts, an
which may be confidered as performing the offices both of ud
tube and fcale of the common thermometer. It is obvious,
that if a body, fo adjufted as to fit exactly at the wider end of
this
:
}
&is Thermometer with the common mercurial ones. 361
this canal, ‘be afterwards diminithed in its bulk by ‘fire, as
the thermometer’ pieces are, it will then pafs further in the
canal, and more and more fo according as the diminution is
greater ; and converfely, that if a body, fo adjufted as to pafs
on to the narrow end, be afterwards expanded by fire, as is the
cafe with metals, and applied in that expanded ftate to the fcale,
it will not pafs fo far; and that the divifions on the fide will be
the meafures of the expanfions of the one, as of the contrac-
tions of the other, reckoning in both cafes from that point to
tie the body was adjufted at firft.
Tis the body whofe alteration of bulk is ‘thus to be mea-
fured, which, in the prefent inftance, isa piece of fine filver :
this is to be gently puthed or flid along, towards the end FH,
till itis {topped by the converging fides of the canal.
K is a little veffel formed in the gage for this particular feries
of experiments, the ufe of which will appear hereafter.
Thecsntraétion which thethermometer pieces receive from fire,
isa permanent effect, not variable by an abatement of the heat,
and which accordingly is meafured commodioufly and at leifure,
when the pieces are grown cold. But the expanjfion of bodies 1s
only temporary, continuing no longer than the heat does that
produced it ; and therefore its quantity, at any particular de-
gree of heat, muft be meafured in the moment while that heat
fubfifts. And further, if the heated piece was applied to the —
cold gage, the piece would be deprived of a part of its heat on
the firft conta&t; and as the gage receives fome degree of expan-
fion from heat as well as the piece, it is plain that in this cafe
the piece would be diminifhed in its bulk, and the gage en-
larged, before the meafurement could be taken. It is therefore
neceflary that both of them be heated to an exact equality; and
in that ftate we can meafure, not indeed the ¢rue expanfion of
Vor. LXXIV. Bbb either,
%
362 Mr. Wepewoon's Method of conneéting ae
either, but the excefs of the expanfion of one above that of the
other, which is fufficient for the prefent purpofe, as we want
only an uniform and graduated effect of fire, and. it is totally
‘immaterial whether that effect be the abfolute expanfion of one
or the other body, or the difference of the two, provided only:
that its quantity be fufficient to admit of nice meafurement.. >
Some difficulties occurred with refpe& to. the choice of a
proper matter for the gage; the eflential requifites of. which
are, to have but little expanfibility, and to bear the neceflary
fires without injury. All the metals, except gold and filver,
would calcine-in the fire: thofe two are: indeed free from that
objection, and accordingly it is of the moft expanfible of them
that the piece is made; but if the gage alfo was made of the:
fame, the meafure itfelf would expand juft as much as the body:
to be meafured, and no expanfion at all would be fenfible; and
though the gage was made of one of thofe metals, and the
piece of the other, the difference between thetr expanfions
would be too {mall to give any fatisfactory refults, as more
than. two-thirds ef the real expanfion of either would be
loft or taken off by the other.
For thefe reafons I, had secourfe to earthy comrpoGicielle
which expand by heat much lefs than metallic bodies, and bear’
the neceflary degrees of fire without the leaft injury. I made:
choice of tobacco-pipe clay, mixed with charcoal in fine pow-'
-
der,, in the proportion of three parts/of the charcoal to five of
the clay by weight. By a free accefs of air, in the burning by
which the gage 1s prepared for ufe, the charcoalis confumed, |
and leaves the clay extremely light and porous; from which»
circumftance it bears fudden alternations of cold and heat, often’
requifite in thefe operations, much better than the clay alone.
Another and more important motive for the ufe of charcoak!
\ Was,
his Thermometer with the common mercurial ones. 363
was, that in confequence of the remarkable porofity which it
produces in the clay, it would probably diminifh the expanfi-
bility, by occafioning the mafs to contain, under an equal fur-
face, a much lefs quantity of folid or expanfible matter. It
may be objected to this idea, that the expanfions of metals,
in Mr. Exticotr’s * and Mr. SMEaton’s + experiments, do
not appear to have any conneCtion at all. with their denfities :
but the cafes are by no means parallel; for there the compari-
. fon lies between different fpecies of matter; but here, between
one and the fame matter in different ftates of compactnefs. If
a metal could be treated as clay is in this inftance, that 1s, if a
~ large bulk of any foreign matter could be blended with it, and
this matter afterwards burnt out, fo as to leave the metallic par-
ticles at the fame diftances to which they had been feparated by
the mixture of it, we may prefume that the metal thus enlarged
would not expand fo much as an equal volume of the folid
metal. Such at leaft were the ideas which determined my
choice to a compofition of clay and charcoal powder; and be-.
ing afterwards defirous of fatisfying myfelf whether they had.
any foundation in fa&, I have, fince the experiments were
made, prepared fome pieces of clay with and without charcoal,
and having burnt them in the fame fire, I ground them at the
fides, to make them both fit exatly to the fame divifion near
the narrow end of the gage; then, examining their expanfions
by equal heats, I found the piece with charcoal to expand enly
one-third part fo much as that without; and thus was fully
fatisfied with the compofition of the gage. ,
To afcertain a fixed point on the fcale for the divifions to be
counted from; the filver piece and gage were laid together for
* Phil. TranfaG. vol. XLVI. p. 485. .
+ Ibid. vol. XLVIII. p. 612. :
Bbb& fome
fhe “~ : Pi — d * } a “ : “4
364 ! Litionmieont $ Method. of connetting — a A
fome time in er water, of the ccc 50° of Fan
RENHEIT: the point which the piece went to in this cold ftate
is that marked o near the narrow end of the gage. The ad-_
juftment is re-examined at the beginning and end of every fuc-
ceeding experiment, left the repeated attrition, in fliding the
eer backwards and forwards, fhould wear off fo much, from
the furface of this foft metal as to occafion an error in the mim.
o% eg
nute’ quantities here meafured.
The apparatus is then expoied fucceflively to different acre
of heat, with the piece lying always in a part of the canal at”
leaft as wide as it is expected to fll when expanded, otherwife
the fides of the gage would be burft afunder by its. .expanfion, ’
as 1 experienced in fome of my firft trials. When the whole:
has received any particular degree of heat defired, the piece is:
cautioufly and equably pufhed along, tll it is ftopped by the
convergency of the fides, of which L always find notice given
me by the gage itfelf (which is {mall and light) beginning to
move upon the continuance of theimpulfe. A flat flip of iron,
a little narrower than the piece, bent down to a right-angle at’
one end, and fixed in a long handle at the other, makes, a con-
venient inftrument for pufhing the piece forward, or drawing it)
back again, whilft red-hot: this inftrument, at every time of
ufing, is heated to the:fame degree as the piece itfelf.
The heat of boiling water is taken without difficulty, by.
keeping the apparatus in boiling water itfelf during a fufficient’
{pace of time for the full heat to becommunicated to it. The,”
water I made ule of was a very fine {pring water, which on)
chemical trials appeared very nearly equal in purity te that of
rain or fnow; and Lhad previoufly fatisfied myfelfy by trials in)
the cold, that the gage and piece being wet, or under water,
made no difference in the meafurement. The expanfion of the
3 filver
his Thermometer with the common mercutial ones. 3.65
filver by this heat, that is, by an increafe of the heat from 50°
to 212°, or a period containing 162° of FAHRENHEIT, was”
juit 8° of the gage or intermediate thermometer M; whence
one of thefe degrees, according to this experiment, containg
joft 20°: of Faurenuert’s. The operation was many times
‘repeated, and the refult was always precifely the fame. |
For the boiling heat of mercury, it was neceflary to A al
ina different manner; not to convey the heat from the mer-
cury to the inftrument, but to convey it equally to them both
from another body. _ I made a {mall veflel for holding the mer-
cury in the gage itfelf, feen at K fig. 4. and more diftin€tly in
fig. 5. which is a tranfverfe feCtion of the gage through this
veflel. The plate CD, which forms the bottom of the canal,
ferves alfo for the bottom of the veflel, which is fituated clofe
to the fide of the canal, and as near as could be to that part of
it, in which both the filver piece, and the divifions required)
for this particular experiment, are contained. By this arrange-
ment it 1s pretumed, that all the parts concerned in 1 the meee
tion will receive very nearly an equal heat.
The gage, with fome mercury in the veffel, was laid upon a
fmooth and level bed of fand, on the bottom of) am iron muffle
kept open at one end; the fire increafed very gradually till the.
mercury boiled, and then continued fteady, fo as juft to keep
it boiling, for a confiderable time. The boiling heat of mercury
was thus found to be 27°4 of the intermediate thermometer,
which anfwering to an interval of 550° of FaHRENHEIT,
makes one degree of this equal to juft 20° of his; a refult cor-
refponding even beyond my expectations with that which
boiling water had given.
Thete ftandard heats of FAHRENHEIT’S shiecaocinene are ob-
tained with little difficulty on a common fire; but it is far
otherwife
356 . Mr. Wevewoon’s Method of conneéting :
otherwife with the higher ones in which mine begins to'app a }
and all the precautions I’ could take,’ by ufing a’ clofe muffle;
{urrounding it as equally as poflible with’ the fuel, varying its”
pofition with refpe&t to the draught of air, &c: proved infuf-
ficient for fecuring the neceflary equality of heat even’ through —
the {mall {pace concerned in thefe experiments. Nor had T.
any idea, before the difcovery of this thermometer, of the
extreme difficulty, not to fay impracticability, of obtaining, |
in common fires, or in common furnaces, an uniform heat’
through the extent even of a few inches. | Incredible as this _
may appear at firft fight, whoever will follow me in the opera-
tions I have gone through, placing accurate meafures of the
heat in different parts of one and the fame veffel, will foon be
convinced of its truth, and that he can no otherwife expe to
communicate with certainty an equal heat to different pieces,
than by ufing a fire of fuch magnitude as to exceed perhaps
fome hundreds of times the bulk of the matters required to be
heated. |
To fuch large body of fire, therefore, after many Feuitlets
attempts in fmall furnaces, not a little difcouraging by the
irregularity of their refults, I at length had recourfe, fitting up
for this purpofe an iron oven, ufed for the burning-on of ena-
mel colours upon earthen ware, about four feet long, by two
and a half wide, and three feet high, which is heated by the:
flame of wood conduéted all round it. An iron muffle, four
inches wide, two inches and three quarters high, and ten’
inches long, containing the gage and piece, was placed in the
middle of this oven, and the vacancy between them filled up
with earthen ware, to increafe the quantity of ignited matter,
and thereby communicate the heat more equably from the *
oven to the muffle. In: fuch a fituation of the muffle, in the’)
center
his Thermometer with the common mercurial ones. 367
eenter of an oven more than five hundred times its own capa-
city, it could not well fail of being heated pretty uniformly, at
leaft through the fmall {pace which thefe experiments re-
quired; nor haveI found any reafon to fufpeét that it was not fo,
. The gage being laid flat upon the bottom of the muffle, with
the filver piece in the canal as before, fome of the clay ther-
mometer pieces were fet on end upon ‘the filver. piece, with
that end of each downwards which is marked to go foremoft in:
meafuring i it; that is, they were in contaét-with the filver in’
that part of their furface by which their meafure is afterwards:
afcertained. I was led to this precaution by an experiment I
had made upon another occafion, in which a number of ‘ther-
momieter pieces having been fet upright upon an ‘earthen-ware’
plate, over a fmall fire, till the plate became red-hot, all “the
pieces were found dimmifhed, fome of them more than two:
degrees, at the lower ends which refted uponthe plate, whilft
the upper ends were as much enlarged, not having yet pafled the
ftage of extenfion which, as obferved in the former paper, al-
ways precedes the thermometric diminution : thusowe fee how’
pundtually every part of the piece obeys the heat that acts-upon it.
_.'The fire about the oven was flowly. increafed for fome hours, ’
and kept as even and fteady as poffible, by.an experienced fire-
man, under my own infpection. Upon opening a {mall door, :
which had been made for introducing the apparatus, and look -
ing in from time to time, it was obferved, that: the muffle,
with the adjacent parts of the oven and ware, acquired a vifible .
rednefs at the fame time; and in the progrefs of the operation,
the eye could not diftinguifh the leaft diffimilarity in the afpe&:
of the different parts ; whereas in {mall fires, the difference: not
only between the two ends of the muffle, but in = lefs
diftances, 1s fuchoas to ftrike the eye-at once.
When
368 » Mr. WEDGwoon’s Method of conneéting %
sais the muffle appeared’ of a low red ‘heat, said % 3
Heel to come fully within the province of my thermometer’, |
it was drawn forward, towards the door of the oven ; and its
own door being then nimbly opened by an affittant, I imme-
diately pufhed the filver piece as far as it would go. But as the -
divifion which it went to could not be diftinguifhed in that:
ignited ftate, the mufHe was lifted out, by means of an iron’
rod pafied through two rings made for that purpofe, with care’
to keep it fteady, and avoid any fhake that might pei the
diplacing of the filver piece. .
_ When grown fufficiently cold to be stated I ised sd
abit. of expanfion which the filver piece ftood at, and the
degree of heat fhewn by the thermometer pieces meafured in
their own gage; then returned the whole into the oven as be-=
fore, and repeated the operation with a ftronger heat, to obtain
another point of correfpondence on the two {eales. ~ ve
The firft was at 2° of my thermometer, which coincided
with 66° of the intermediate one; and as each of thefe laf
has been before found to contain 20 of FAHRENHEIT’s, the’
66 will contain +1320; to which add 50, the degree of his
{cale to which the o of the. intermediate thermometer was ad-
jufted, and the fum, 1370, will be the degree of FAHREN-
HEIT’s correfponding to my 2°3. t
The fecond point of coincidence was at 6° of mine, and
92° of the intermediate; which 92 being, according to the’
above proportion, equivalent to 1840 of FaAuRENHEIT, add 50 ©
as before to this number, and my 6°: is found to fall upon thet
18g9o0th degree of FAHRENHEIT. |
‘It appears from hence, that.an interval of 4 degrees upon mine ~
is equivalent to.an interval of 520° upon his; confequently 1 of)
mine to 130 degrees of his; and that the o of mine correfponds
to
e
ee
bis Thermometer with the common mercurial ones. 369.
to his:1077°. Several other trials were made, which gave re-
fults fo nearly alse that I have: little apprehention of any
material error.
From thefe data it is eafy to reduce Shee foate to the ae
through their whole range ; and from fuch reduction it will
appear, that an interval of near 480° remains between them,
which the intermediate thermometer férves as a meafure for;
that mine includes an extent of about 32000 of FAHRENHFIT’s.
degrees, or about 54 times as much as'that between the freez-
ing and boiling points of mercury, by which mercurial ones
are naturally limited; that if the {cale of mine be produced
downwards, in the fame manner°as we have fuppofed Fan-.
RENHEIT’s to be produced upwards, for an ideal ftandard, the —
freezing point of water would fall nearly on 8° below o of.
mine, and the freezing -point of mercury a little below 8° ;.
and that, therefore, of the extent.of now meafurable heat,
there are about _{,ths of a degree of my {fcale from the freez-
ing of mercury tothe freezing of water; 8° from the freezing
of. water to full i ignition 5 and 160° above this to ye nievel
ae I have hitherto attained. | |
As we are now enabled to compare not only the higher My.
grees among themfelves, and the lower among themfelvés,
upon their refpective feales, but likewife the higher and lower
with each other in every flage, it may, be proper to take a ge~
neral view of the whole range of meafurable heat, as exprefled
both in Fanrenuerr’s denominations and in mine; and for,
this purpofe I have drawn up a little table of a few of the prin-.
cipal points that have been -afcertained, to thew their mutual
relations or proportions to each other: any other points that.
have been, or hereafter may be, obferved, by thefe or any
other known thermometers, may be inferted at pleafure. .
-Vou. EXKIe Cce Extremity
he age sas Wenewoon's Method of connefting — i
| a Tamas S Wend :
oe of the feale bt my, eee 82297?) 24d orlyt tg
Greateft heat of my {mall air-furnace - 23 879, 1Odrors
€aft iron melts. - ~ hye) sy tre) i aye aged
Greateft heat of a common fmith’s forge, 17327. 125§.0..
Welding heat of iron, greate non do Aayiotud 34 7es99 So aa
»deakkionotrrody einihmke7 ey oso@leids
Fine gold melts - Plott na chee Ra oes tae
Fine filver melts < ~ 12 KATZ as 2816
Swedith copper melts MASS ot SOP ied aah
Brafs melts - : Ai a 3807 2i
Heat by which myenamel colours are burnt on (1857) 6
Red-heat fully wifible in day-light - 1074 Or.
Red-heat fully vifible in the dark - 9 94Fc ESisic'n?
Mercury boils - - - 680) | cy Behetehetl
Water boils - ° . BEey ibe ihe
Vital heat - - - 97 7 dd fiat
Water freezes - - ‘o9t) oft ot vQ@oreets Ohtees
Proof f{pirit freezes - i= = Duatoneleaiie
The point at which mercury ap key : oil
confequently the limit of mercurial $ about 40 $525
thermometers, = ‘ j
To affift our conceptions of this fubje&, it may be proper to
view it in another light, and endeavour to prefent it to the
eye; for zumbers, on ahigh fcale, are with difficulty eftimated
and compared by the mind. I have therefore completed the
{cales of which a part is reprefented in fig. 1. and 3. by conti-
nuing the fame equal divifions, both upwards and downwards,
as far as the utmoft limits of heat that have hitherto been
attained and meafured *. | | 0d eS HiKk
* Mr. WEpGwoop prefented this, in the fotm of a very long roll, to the Societys
Ol ie
bis Thermometer. with the common mercurial ores. ; aun
Ina {cale of heat drawn up in this manner, the compara- .
tive extents of the different departments of this grand and ~
univerfal agent are rendered confpicuous at a fingle glance of
‘the eye. Wertee at once, for inftance, how fmall a portion
of it is concerned in animal and vegetable life, and in the
ordinary operations of nature. From freezing to vital heat is
"barely a five-hundredth part of the fcale; a quantity fo inconfi-
derable, relatively to the whole, that in the higher flages of
ignition, ten times as much might be added or taken away,
without the leaft difference being difcernible in any of the
appearances from which the intenfity of fire has hitherto been
judged of. From hence, at the fame time, we may be con-
vinced of the utility and importance of a phyfical meafure for
thefe higher degrees of heat, and the utter infufficiency of the
common means of diferiminating and eftimating their force. 1 3
have too often found. differences, aftonifhing when confidered
as a part of this {cale, in the heats of my own kilns and ovens,
“without being perceivable by the workmen at the time, or till
the ware was taken out of the kiln.
SINCE the foregoing experiments, were made, I have feen
a very curious Memoir by Mefl. Lavorsier and De LA Place,
containing a method of meafuring heat by the quantity of ice.
which the heated body is capable of liquefying. ‘The applica-
tion of this important difcovery, as an intermediate ftandard
meafure between FAHRENHELT’s thermonfeter and mine, could
not efeape me, and I immediately fet about preparing an appa-
ratus, and making the ies neceflary for that pur-
Cece Sale;
ik coc aieaa i
ey Mr. BOWERY 5 Methoul ‘of swiilettag
-pofe; in hopes either of attaining by this method a greater de-
_ gree of accuracy than T could expect from any other means, or
of having what I Rad already done confirmed by a Aeris of
experiments upon a different principle.
But in the profecution of thefe experiments 1 have, to my
“great mortification, hitherto failed of fuccefs; and I fhould.
have contented myfelf for the prefent with faying little more
than this, if fome phenometia had not occurred, which pine?
to me not unworthy of farther inveftigation. |
The authors obferve, that if ice, cooled to whatever degree
below the freezing point, be expofed to a warmer atmofphere,
it will be brought up to the freezing point through its whole
~mafs before any part of its furface begins to hquefy ; and that
-confequently ice, beginning to melt on the furface, will be
always exactly of the fame temperature, viz. at the freezing
point; and that if a heated body be inclofed in a hollow {phere
af fuch ice, the whole of its heat will be taken up in lique-
fying the ice; fo that if the ice be defended from external
warmth, by furrounding it with other ice in a feparate veftel,
the weight of the water produced from it will be exaétly pro-
portional to the heat which the heated body has loft; or, im
other words, will be a true phyfical meafure of the heat.
For applying thefe prinetples in practice, they employ’a tim
veel, divided, by upright concentric partitions, into. three
compartments, one within another. ‘The innermoft compart-
ment is a wire cage, for receiving the heated body. The fecond,
jurrounding this eage, is filled with pounded ice, to be melted
by the heat; and the outermoft is filled alfo with pounded ice, to
detend the former from the warmth of the atmofphere. The
furft of thete ice compartments terminates at bottom in a ftem
ike a funnel, through which the water is conveyed off; and
the other ice compartment terminates in a feparate canal, for
difcharging
“>
~
~
} } his Thermometer with the common mercurial ones. haais
“ difcharging the water into which haf ice is reduced. As foon
‘as the heated body is dropped into the cage, a cover is put on,
which goes over both that and the firft ice’ compartment;
“which cover is itfelf a kind of fhallow veffel, filled with
“pounded ice, with holes in the bottom for permitting the water
from this ice to pats into the fecond compartment, all the
liquefaétion that happens here, as well as there, being the
effe& of the heated body only. Over the whole is placed ano-
ther cover with pounded ice, as a defence from external
“warmth.
As foon as this difcovery came to my knowledge, on the 23d
‘of February, athaw having begun three days before, after a
‘froft which had continued with very little intermiffion from:
the 24th of December, I colleted a quantity of ice, and ftored
“it up in a large cafk ima cellar.
I thought it neceffary to fatisfy myfelf in the firft place, by
‘a€tual experiment, that ice, how cold foever it may be, comes
up to the freezing point through its whole mafs before it be-
gins to liquefy on the furface. For this purpofe I cooled a large
fragment of ice, by a freezing mixture, to 17° of FaHREN-
-HEIT’s thermometer, and then hung it up in a room whofe
temperature was 50°. When it began to drop, tt was broken,
‘and fome of the internal part nimbly pounded and applied to.
the bulb of a thermometer that was cooled by a freezing mix-
ture below 30°. The thermometer rofe to, and continued at,
32°; being then taken out, and raifed by warmth to 40°, fome
more of the fame ice, applied as before to the bulb, funk it
again to 32°; fo that no doubt could remain on this fubje@.
Apprehenfive that pounced ice, dire&ted by the authors, might
imbibe and retain more or lefs of the water by capillary attraction,
according to circumftances, and thereby occafion fome error in
the refults, 1 thought it neceflary to fatisfy myfelf in this refpect
alf{e
374 Mr. Wepewoon’s Methad of connecting
alfo by experiment. I therefore pounded. foun ice,, and laid it
in a conical heap on a plate; and having at hand | fome. water,
coloured with cochineal, I poured. it gently into the plate, ate
fome diftance from.the:heap:: .as foon as it came in contact with ©
the ice, it rofe haftily up to the top; and on. lifting up. the :
lump, I found that it held the water, fo taken up,: as a fponge
does, and did not drop any part of it till the heat of my hand,
as I f{uppofe, began to liquefy the mats. On further trials I |
found, that in pounded ice prefled into a conical heap, the
coloured water rofe, in the fpace of three minutes, to the
height of two inches anda half; and by weighing the water
employed, and what remained upon the plate unablorbed,, it
appeared, that. four ounces of ice had thus taken up, and re-
tained, one ounce, of water.
To further afcertain this abforbing power, in different cir-—
cumtftances, more analogous to thofe of the procefs itfelf, I
prefled fix ounces.of pounded ice pretty hard into the funnel,
having firft introduced a wooden core in order to leavea proper
cavity in the middle: then, taking out the core, and pouring —
an ounce of water upon the ice, I left the whole for half an
hour; at the end cf which time the quantity that ran oif was
only 12 pennyweights and 4 grains, fo that the ice had retained
7 pennyweights aud 20 grains, which is nearly one-twelfth of
itsown weight, and two-fifths of the weight of the water.
‘Thefe previous trials determined me, inftead of ufing pounded
icc, to fill a proper vefiel with a folid mafs of ice, ke means of
a freezing mixture, as the froft was now gone, and then expofe
2t to the atmofphere till the furface began to liquefy. The ap=
paratus I fitted up for this purpofe was made of earthen ware
well glazed, and is reprefented in fig. 6, (tab. XV.).
A, is
his Thermometer with the common mercurial ones. B09
| A, isrwlarge funnel, filled with a folid mafs of ice!)..B sa
cavity in the middle of this ice, formed, part of the way, by.
feraping igith a ikmife, and for the rematming: part, by boring
with a hot iron wire. C, one of my thermometer pieces,
which ferves forthe heated body, ‘and refts upon a coil of brafs
wire: it had previoutfly been burnt with ftrong fire, that there
might be no danger of its fuffering any further diminution of
its: bulk by being heated again for thefe-experiments.. D, a
cork {topper in the orifice of the funnel. E, thie exterior veflel,
having the {pace between its fides and the included funnel A,
filled with pounded ice, asa defence to the ice in the funnel.
F, a cover for this exterior vefiel, filled with pounded ice for the
fame purpofe. G, a cover for the funnel,; filled alfo with
pounded ice, with perforations in the bottom for aul wIES) the
water tromthis ice to pafs down tothe funnels,
. The thermometer piece was heated m boilmg water, taken
up with a pair of {mall tongs equally /heated, dropped. in-
ftantly into the cavity B, and the covers put on as expeditionfly
as poflible; the bottom of. the funnel being’ pievioully. corked,
that the water might be detained ull at thould. part with,all
its heat, and likewife to prevent the. water from the other: ice,
which ran down on the outfide of the funnel, from, a
with it. WW | |
‘After ftanding about ten minutes, the er was ae out;
wiped dry, and uncorked over a weighed cup: the water that
ran out weighed 22 grains.’ Thinking this quantity too {mall,
as the piece weighed 72 grains, I repeated:the experiment, and.
kept the piece.longer in the funnel; but the water this-time
weighed only 12 grains. ‘Being much diflatisfied with. this
tefult, I made a third trial, continuing the: picce much longer
in the cavity ; but the quantity of water was now ftul lefs, not
| 7 amounting
|
376 Mr. Wepcwoon’s Method of conneéiing |
amounting to quite three drops; and, to my great furprife; I j
found the piece frozen to the ice, fo as not to be eafily got off) —
though all the ice employed was, at the PEGI of the ee |
riment, in athawing ftate.
I had prepared the apparatus bfak! taking the boiling hed as
mercury; but being entirely difcouraged by thefe very unequal:
refults, I gave that up, for the prefent at leaft, and : heating:
the piece to 6° of my thermometer, turned it nimbly out of:
the cafe in which it was heated into the cavity, throwing)
fome fragments of ice over it. In about half an hour, I drew!
off the water, which amounted to 11 pennyweights; then:
ftopping the funnel again, and igi the covers, I left the’
whole about feven hours.
At the end of that time, I found a confiderable. quantity of,
water in the funnel: the melting of the ice had produced a —
cavity between it and the fides, great part of the way down,
which, as well as that in the middle, was nearly full. The
water neverthelefs ran out fo flowly, that I apprehended fomes=:
thing had ftopped the narrow end of the funnel, but the true;
caufe became afterwards apparent upon examining the ftate of;
the ice. The fragments which I had thrown over the thermo=;
meter piece were frozen entirely together, and in fuch a form as -
they could not have aflumed without frefh water fuperadded and
frozen upon them, for the cavities between them were partly
filled with new ice. I endeavoured to take the ice out with
my fingers, but in vain; and it was with fome difficulty L
could force it afunder even with a pointed knife, to gét at the,
thermometer piece.: When that was got out, great- part of
the’ coiled wire was found envelopéd in new ice. . The paflage
through the ice to the ftem of the funnel, which I had made
pretty wide with a.thick iron wireired-hot, was fo-nearly clofed
terer ~ up,
Bis Thermometer with the common mercurial ones. ‘BR
up, that the flow draining off of the water was now fufficiently
accounted for, and indeed this draining was the only apparent
mark of any paflage at-all. On taking the ice out of the fun-
nel, and breaking it to examine this canal, I found it almoft
entirely filled up with ice projeting from the folid mafs in cry-
ftalline forms, fimilar in appearance to the cryftals we often
meet with itt the cavities of flints and quarzofe fiones.
If, after all thefe circumftances, any doubt could have re-
mained of the ice in queftion being a new production, a fa&
which I now obferved muft have removed all fufpicion. I
found a coating of ice, of confiderable extent and perfectly
tran{parerit, about a tenth of an inch in thicknefs, upon the
-outfide of the funnel, and on a part of it which was not in
conta& with the furrounding ice, for that was melted to the
diftance ef an inch from it. 3
- Some of the ice being fcraped off from the infide of the
linia, and applied to the bulb of the thermometer, the mer-
cury funk from 50° to 32°, and continued at that point till the
ice was melted; after which, the water being poured off, it
rofe in a little time to 47°.
Aftonifhed at thefe appearances, of the water freezing after
it had been melted, though {Grrounded with ice in a melting
ftate, and in an atmofphere about 50°, where _no part of the
apparatus or materials could be fuppofed to be lower than the
freezing point, I fufpected at frit that fome of the falt of the
freezing mixture might have got into the water, and that this,
in diffolving, might perhaps abforb, trom the parts contiguous.
to it, a greater proportion of heat than the ice of pure water
does. But the water betrayed nothing faline to the tafte, and
Thad applied the freezing mixture with my own hands with
great care, to prevent any of it being mixed with the water.
ear TXXIV. Ddd 3 berg a
378 | Mr. ‘Wenewoon's Method of connesting ih
To Mgt ks all doabts, He wen t! iis point, Bae
thawing, in ae ee Be going to fetch the 3 ice, ee
examining it in the caik i which it was kept, I was perfeétl ;
fatisfied with the appearances I found aha - for though much
of it was melted, yet the ae Toa were frozen io” fo
fragments had been broken and rammed into the eafk with a R
iron mall. | q
Bey porcelain cup being laid’ upon fome of this ice about half a
an hour, in a room whofe temperature was 50°, it was found
pretty firmly adhering, and when pulled off, the ice exhibited
an exact impreffion of the fluted part of the cup which it had
been in contact with; fo that the ice muft neceflarily have
liquefied firft, and afterwards. congealed again. This was req
peated feveral times, with the fame event. Fragments. of the
ice were hkewife apphed to one another, to {ponges, to pieces:
of flannel and of linen cloth, both meuft and dry: all thefe, 18
a few feconds, began to = era and in about a migute were
frozen fo. as to require fome force to. feparate them. After
ftanding an hour, the cohefion was fo firm, that on pulling
away the fragments of ice from the woollen and fponge, they
tore off with them that part of the furface which they were
in contact with, though at the fame time both the {ponge and:
flannel were filled with water which that very ice had pro-
duced. : &
To make fome eftimate of the force of the conselanoal
which was ftronger on the two. bodies laft mentioned than on
5 linen
bis Thermometer with the common mercurial ones, 379
linen, I applied a piece of ice to a piece of dry flannel which -
weighed two pennyweights anda half, and furrounded them
with other ice. After lying together three quarters of an.
hour, taking the piece of icein my hand and hooking the flan-
mel toa ae I found a weight of five ounces to bee neceffary
for pulling it off, and yet fo much of the ice had liquefied AS
to increaie the weight of the flannel above 12 pennyweights. by
then weighed the piece of ice, put them tegether again, and
four hours after found them frozen fo aeinly as to require <8"
ounces for their feparation, although, from 42 pennyweights
of the ice, 15 more had melted off: the furface of conta& was:
at this time nearly afquare inch. I continued them again toge-
ther for feven hours; but they now bore only 62 ounces, the’
ice being diminifhed to 14 pennyweights, and the furface of °
contact reduced to about fix-tenths of a f{quare inch.
Having .feen before that pounded ice abforbs water in very
confiderable quantity, I fufpected that fomething of the fame
kind might take place even with entire mafles; and experiment
foon convinced me, that even apparently folid pieces of ice will.
imbibe water, flower or quicker according to its {tage of decay.
I have repeatedly heated fome of my thermometer pieces, and
Jaid them upon ice, in which they made cavities of confidera-
ble depth, but the water was always abforbed, fometimes as.
aft as it was produced, leaving beth the piece and the ea
dry.
Thus, though I cannot fufficiently oleh how much I ad-’
mire the difcovery that gave rife to-thefe experiments, I have.
_neverthelefs to lament my not being able to avail myfelf of it
at prefent for the purpofe I wifhed to apply it to. !
That in my experiments the two feemingly oppofite procefies
of nature, congelation and liquefaction, went on together, at
Dddz the
389. Mr. Wepewoon's Method of conneting —
the fame inftant, in the fame veflel, and-even in the ech
fragment of ice, isa faét of which I have the fulleft” evidence
that my fenfes can give me; and [ fhall take the liberty of fug-
gelting a few hints, which may tend perhaps to elucidate their —
caufe, and to fhew that they are not fo incompatible as at firft
fight they appear to be. a
It oceurred to me at firft, that water highly attenuated and
divided, as when reduced into vapour, may freeze with a lefe ~
degree of cold than water in ‘its aggregate or grofler form 3.
hence hoar-froft 1s obferved upon grafs, trees, &c. at times
when there is no appearance of ice upon water, and when the
thermometer is above the freezing point*. BorRHAAvE, I
find, in his elaborate theory of fire, affons 33° as the freezing
point of vapour, and even of water when divided only by being
imbibed in a linen cloth. )
* Tam aware, that experiments and obfervations of this kind are not fully’
cecifive; that the atmofphere may, in certain circumftances, bemuch warimer or
colder than the earth and waters, which, invirtue of their denfity, are far more
retentive of the temperature they have once reccived, and lefs fufceptible of
tranfient imprefions ; that even infentible undulations of water, from the flighteft
motion of the air, by bringing up warmer furfaces from below, may prove a further
impediment to the freezing; and, therefore, that the degree of cold, which is
fufficient to produce hoar-froft, may poffibly, if continued long enough, be fufi-
cient alfo te produce ice Iam not acquainted with any fatisfactory experiments.
or obfervations yet made upon the fubjeSt; nor do I advance the principle as a
certain, but as a probable one, which occurred to me at the moment, which is
countenanced by general obiervation, and confentaneous to many Known fadts ;
for there are numerous initances of bodies, in an extreme flate of divifion,’
yielding ealily to chemical agents which, before fuch divifion, they entirely refift s
thus fome precipitates, in the very fubtile ftate in which they are at firft extricated
from their diffolvents, are re-diffolved by other menftrua, which, after their
concretion into fenfible molecule, have no action upon them at all,
7 Now,
bis Thermometer with the common mercurial ones. 381.
Now, as the atmofphere abounds with watery vapour, or
water diffolved and chemically combined, and muft be parti-
cularly loaded with it in the neighbourhood of melting ice;
as the heated body introduced into the funnel muff neceflarily
convert a portion of the ice or water there into vapour; and
_ as ice is known to melt as foon as the heat begins to exceed ao:
or nearly one degree lower than the frzezing poimt of vapour ;
I think we may from hence deduce, pretty fatisfactorily,. all
the phenomena I have obferved. For it naturally follows
from thefe principles, that vapour may freeze where ice is
melting; that the vapour may congeal even upon. the furface
of the melting ice itfelf; and that the heat which (agreeably
to the ingenious theory of Dr. BLack) it emits in freezing, ~
may contribute to the further liquefaction of that very ice upon
which the new congelation is formed.
Y would further obferve, that the freezing of water is at-
tended with plentiful evaporation in a clofe as well as an
open veffel, the vapour in the former condenfing into drops on
the under fide of the cover, which either continue in the form
of water, or affume that of ice or a kind of fnow, according»
to circumftances * ; which evaporation may perhaps be: attri-.
buted to the heat that was combined with. the water, at this
moment rapidly making its efcape, and carrying part of the
aqueous fluid off withit. We are hence furnifhed with a frefh
and continual fource of vapour as well as of heat; fo that the
procefles of liquefation and congelation may go on untmter-
ruptedly together, and even necefiarily accompany one another,
although, as the freezing muft be in an under proportion to the
melting, the whole of the ice mutt ultimately be confumed.
* See Mr. Baron’s paper on this fubject, m, the Memoires of the Academy
of Sciences at Paris for the year 1753.
- In
4 wy i bres
I i ,
382 Mr. Wuvewoon’s Method of conneding
Inthe remarkable inftance of the coating of ice on the out-
fide of the throat of the funnel, there are fome other circum- .
flances which it may be proper to take notice of., Neither the
cover of the outer veflel, nor the aperture in its bottom which !
the ftem of the funnel pafied through, were air-tight, and the _
melting of the furrounding ice had left a vacancy of about an
inch round that part of the funnel on which the cruft had
formed. As there was, therefore, a paflage for air through the
veffel, a circulation of it would probably take place: the cold
and denfe air in the veffel would defcend into the rarer air of
the room ‘then about 50°, and be replaced by /air from above.
The effect of this circulation and fudden refrigeration of the.
air will be a condenfation of part of the mozfture it contains
upon the bodies it is in contaét with: the throat of the funnel,
being one of thofe bodies, muft receive its fhare; and the de-
eree of cold in which the ice thaws being fuppofed fufficient
for the freezing of this moift vapour, the contact, condenfa- .
tion, and freezing, may happen at the fame inftant.
fs
‘The fame principles apply to every inftance of congelation
that took place in thefe experiments; and a recollection of par-
ticulars which pafled under my own eye convinces me, that
the congelation was ftrongeft in thofe circumftances where va-
pour was moit abundant, and on thofe bodies which, from
their natural or mechanic ftructure, were capacious of the
greateft quantity of it; ftronger, for inflance, on fponge
than on woollen, {tronger on this than on the clofer texture of.
linen, and far ftronger-en.all thefe than.on the compact furface
of porcelain.
If, neverthelefs, the principle I have aflumed (that water
highly attenuated will congeal with a lefs degree of cold than.
swater in the mafs) fhould not be admitted; another has above
ee
been
bis Thermometer with the common mercurial ones. 383
‘been hinted at, which experiments have decidedly eftablifhed,
‘from which the phenomena may perhaps be equally accounted
for, and which, even though the other alfo.is received, muft
be fuppofed to concur fer fome part of the effet; I mean, that
“evaporation produces cofd; both vapour and fteam carrying off
{ome proportion of heat from the body which produces them.
If, therefore, evaporation be made to take place upon the fur-
face of ice, the contiguous ice will thereby be rendered colder ;
and as it is already at the freezing point, the fmalleft increafe
of cold will be fufficient for frefh congelation. It feems to be
on this principle that the formation of ice is effected in the
Eaft Indies, by expofing water to a ferene air, at the coldeft
feafon of the year, in fhallow porous earthen veflels: part of
the water tranfudes through the veflel, and evaporating from.
the outfide, the remainder in the veffel becomes cold enough to.
freeze ; the warmth of the earth being at the fame time in-
tercepted by the veffels being placed upon bodies little difpofed
to conduct heat*. If ice is thus producible in a climate where
natural ice is never feen, we need not wonder that congelation
fhould take place where the fame principle operates amidft
actual ice.
It has been obferved above, that the heat emitted by the
eongealing vapour probably unites with and liquefies conti-
guous portions of ice; but whether the whole, either of the
heat fo emitted, or of that originally introduced into the fun-
nel, is thus taken up; how often it may unite with other por-
tions of ice, and be driven out from other new congelations ;
whether there exifts any difference in its chemical affinity or
* See a defcription of this procefs in the Philofophical Tranfactions, vol.
LEV. p. 253.
elective
334 ‘Mr. Wevewcoon's Method of connecting, &c.
elective attraCtion to water in different ftates and the conti-
guous bodies; whether part of it may not ultimately efcape,
without performing the office expected from it upon the ice;
and to what diftance from the evaporating furface the reffi-
gerating effet of the evaporation may extend; muft be left
-for further experiments to determine. Ae Sb
"Vee MATX WL 'AIXX T 7 SCO SOT
LPiittos. Trans. Vol. E XXIV. Tab XIV p.354.
1000
S00
Seiot
ets
Ns iv
ig
Ss
30
20
r@
~
Vol L XXIV, Tab. RV yp. 384,
= Philos Trane VoL XXIV, Tab. XVy. 384
—$ <=
Bajore
[385 J
AXVII. On the Summation of Series, whofe general Term is a
determinate Function of z the Diflance from the firft Term of
the Series. By Edward Waring, M. D. Lucafian Profeffor
of the Mathematics at Cambridge, and Fellow of the Societies
_ ¥ London and Bononia.
Read May 20, 1784.
see PR O| eB Loe M.
| TA E fum 3 being given, to find a feries of which it is the
UM
1. Reduce the fum S into a converging feries, proceeding
according to the dimenfions of any {mall quantities, and it is
done. For example: let any algebraical fun@ion,S of an un-
known or {mall quantity x be affumed, reduce it into a con-
verging feries proceeding according to the dimenfions of x, and
there refults a feries whofe fumis S.. 2. Let A, B, C, &c. be
algebraical functions of «3 reduce the f Ax, f. Bx, f Cx, &c.
into a’converging feries, proceeding according to the dimen-
fions of «, and the problem is done.
It is always neceflary to find the values of +, between which
the abovementioned ferictes converge. Reduce the algebraical
‘function S in the firft example, and the algebraical functions
A, B, C, &c. in the fecond into their loweft terms; and in fuch
‘a-manner, that the quantities contained in the numerator
and denominator may have no denominator: make the deno-
Vor. LXXIV. Eee minator
is
ee Dr. Wantne on the
minator in the firft example, and the denominator in the
cond, and every diftinét irrational- quantity contained in the
relpeclively =o; and alfo every. diftin& irrational quantity. con
tained in the numerators =o. Suppofe « the lealt root affir~
mative or negative (but not =o) of the abovementioned re~
fulting equations ; then a feries afcending according to: the aie
menfions of x will always converge, if the value of eh
is contained between a and —a; but # # be greater
than # or —a, the abovementioned feries will diverge.. Let
g be the greateft root of the abovementioned refulting equa-
tions; then a feries defcending according’ to the reciprocal di-7
menfions of x willjconverge, if.w be greater.than = 7; but, if
lefs, not, . When impoffible roots 4 =& b/ SI are contained in
the equations, an afcending feries: will converge, if x be lef.
than the leaft root = #, and = (¢—4), and = (¢+6); of
more generally, if w be lefs than. the leaft root == a, and vel
at an infinite diftance 2, be infinitely lefs than |
/(n—t Gi 2-2 An 3
2qan—-2.N» ar—2 b?+ DS 6 ‘wy a . > < 2 gt—4 b+. &c.. aTé
3 ‘
~ 7 . ra > eo.
(a*+5°)"
a defcending feries will always converge, when w is greater)
than the greateft root of the refulting equations 3, and a*—*,,_
when # 1s fidlite, is infinitely Sapa than (4+ 6)" and (4 = 4)"57
n-~ n—2
or more generally than 2a"-22”.
b
&
oe a’—4h* — &e °
Summation of Series. 387
ef equal magnitude, as +eand « ai/-1, &c. andx=a;
in which cafe fometimes both fericfes may become the fame
converging feries, &c.
“When wx, in the preceding cafes, is equal to the leaft or
greateft root, the feries will fometimes converge, and fome-
times not, as is fhewn in the above-mentioned chapter. Whe-
ther the fum of a feries, whofe general term is given, can be
found or not, will in many cafes appear from the law of the
multinomial and other more general feriefes.
“2. There are feriefes which always converge, whatever may
be the value of x; as, for example, the feries I oe
I
me tale
ee may be the ae of «3 but it may be obferved, that
thefe feriefes never arife from the expanfion of algebraical
functions of x, or the before-mentioned fluents; but, ina few
cafes, they may from fluxional equations. ‘There are alfo
feficics| Which “mever converge as 1 ft 3x31 0 2. on
+1.2.3.4%'+&c. to which the preceding eee may be
applied.
3: In the year 1754 fome papers, which contained the firft
edition of my Meditationes Algebraic, were fent to the Royal
Society, in which was contained the following rule, viz. let S
be a given function of the quantity x, which expand into a
feries (2 + bx" + cx" 4 &c.) proceeding according to the dimen-
fions of «; in the quantity S, for x" write ax”, Bx”, yx", &c.
where «, @, y, &c. are roots of the equation x7—1=0; and
let the refulting quantities be A, B, C, D, &c. then will
A+B-+C+D-+&c.
eee be equal to the fum of the firt, 27+-1, 32+1,
Pa * 4 8ec.ort + ar ;+3 4+ &c. &c. always converge,
&e. terms 7% infinitum. ‘This method, in the preface to the
Eee 2 Jatt
388 Dr. WARING on the : a
Jaft edition of the Meditationes: fe ies 18- rendered: more: |
correct and general. Aid
4. Let the fum of a feries required be- exipisitedl iy a sais
tion of a quantity s, the diftance from the firft’ term of the
feries, then will the general term be the difference between the:
two fucceffive fums generally expreffed.
5. Let the general term: be-an algebraical funtion: of ais
ft, let it eR cab sO :
Tit, let 1 be Ste.stetl.2+e+2...2+e+n—1
and are whole numbers; and m (if the fum of aninfinite.
{cries of terms. is required) lefs than 2 by two, or more
Re mm
then the general term el tel +e ne
o . Z+ . a
= 'T, where m.:
e-ebe+lsztet+2..0. pet nee
Ste. Ztet+i ft Base ~-Ste+1 .Steta:
hs 0. ah
——_ 4 i pe.
ate. Steti.stet2.zte+3 Shee Stbetl...zstet+a— 1
whence if
ebete.atetsestet4..-zbern—ise” “+ Az” 3 Bees tales
StE+3. S++ 4. Stet 5..- Spepu— 12" 34 Aly” 44 BaP are
etet4.z2+e+5.--2%+e+2— Tae. tT AUS Be +&c. and fo :
on; then, if m=2-2, willy=a, 3=b—yA, e=c—3A’— Be
C=d—-<A’” —JB’—yC, &c.; whence the integral ‘tz infinitum, .
: ‘ : ; ¥y d
eye t ite feries, will ——_____-
or fum of the infinite feries, be Tap) See ee
£
ne ge, i | ri
2.0 She. Sel «Spet+2 &e.
The reduction of the general term T into quantities of the”
before given formulz was publifhed in the Meditationes, printed
in the year 1774. It was before reduced into formule of the
fame kind nearly by Mr. Nrcuoxe in the ParisA@s.
2d, Let:the general term be-T’ = .
ax? + beh +x? 4 &e, ‘?
BPE BPEL BLE LI Be port XStfietfpiwspfpmNi Katg-e+ Epi ete plas XK Ke
where |
|
Summation of Series. 389
where 4 is a whole number lefs than 2+m4+/+4&c. (if it be
ereater, then the fra¢tion can eafily be reduced into a rational
quantity ax’—"—"—'—** + &c, and a fraction of the'before-men-
a al
tioned kind); then VU gh = (ae te + &c.) +
8 ea 6”
(gary ~-2+et+i1 uss a Page pagel rita i Zte+t + &c.) +
Piaaeie OT is O05) Coty fr i eae ny 1 |
E> Saag tf. Btft+i.ztf+2 2tg.z+g+1.2+e+2
: 9 F Xo ; xy’
&c. eee (ee EMOTR ay ekg NUE Ry os VO
ik ) aes Give RE ef see ie tee
: ay ‘ / % 4
pr f iS 2 Ww H . . i
emia ~2t+g+1..2+g+/—1 +.&c ) 2 whence it¢ integral 1n tn
fuitum,,that is, the.fum of the infinite feries can be found.
melicn @= 0.4 =0, (eo = 0, c.; and confequently Ab not
greater than #+- +/+&c.—2; otherwife-not. If 4 is not
greater than 7 -+m +/+ &c. —2, then willa te’ +a” +&c.=0,.
for elfe the fum would be infinite.
Let the number of quantities (¢, /, g, &c.) ber, then from .
y independent. integrals of a feries, whofe term _is_’I’; or
from (r —1) independent {urns of infinite feriefes, whofe term
is I”; that is, where / is not greater than n+m+/4+&c. — 23
can be deduced the fum of all infinite feriefes of the before- -
mentioned formula, whofe general term isv EL’.
If any factors are deficient in the denominator, as fuppofe the
term to be stexz+e+3x2%+e+2-—1; multiply the nu-
merator and denominator by the deficient factors, viz. by
epeta.ztetaxetet+q).sbepo..stetn—2, andit
acquires the preceding formula; and fo in:the following
examples.
3d, Let the denominator be x + o x oa eae iy
ee BSG Le BO Ol ES Ng EN Seen?
Met? «6 KE OCPA KE AWE eK ee wed. x:
#*+¢é
*
39° Dr. WARING on the a
er eer ree pera ora
ted whi pet i &e xwtf xatfriruxtfy+2.., x.
a ee ix &c. =D, where z, 2’, oe Sc. 5) ag &c. are’
a tebe "shez bP ++ 8c. :
D
=T”’; then, if the dimenfions of = in the numerator be
lefs than its dimenfions in the denominator, will ey A =
& a al! Pie fa 8. N a is
(2a Bien Cor ani Fea sy GHP
ge Sree 0
pire in anal there will be included all terms of the formule,
whole numbers; and the general term 1s |
+ &c.) + &c;
A(ayesie mett) |
(ste? - (ztet1)° - . Gee
Batre! Gt!) Sts
(tf)? + @tftnh ++. @Hftit ”
C Cetetutiyha(tete?) ge
Ceteteyh > (etebebiyh es (abete diy 7
where A, B, C, &c. a, «’, &c. B, B’, &c. y, 6, &c. denote in=
variable quantities; and p, pf’, p’’, &c. are whole numbers not
greater than =, e, 7’, &c. refpectively; andz, 7’, 7’, &c. ate
whole numbers not greater thanz=1, m—1, &c.
If all the quantities @, a’, «'’, &c. , B’, B”’, &e. &c. are
=o, the fum of the feries can be expreffed in finite terms of
the quantity z, otherwife not; and alfo if 4 be lefs than the
dimenfions of sin the denominator by two or more, then will
e+@6+&c.=0, otherwife the fum would be infinite. |
From 7+ 7’ +e+&c.=1 independent fums of infinite fe-—
tiefes of this kind can be deduced the fums of all infinite
feriefes of the fame kind,
2 Thigh
Summation of Series. 391
-/This method may be extended to infinite feries, in which
exponentials as e* are contained, which will eafily be feen from.
fome fubfequent propofitions ; but in my opinion the fubfequent
méthod of finding the fum of feriefes is tobe preferred to the
preceding one, both for its generality and facility.
6. 1. Let the general term be (ax? + bzP—? 4 xh? 4 Bc. De
(ste)? . (2+e+1)7*. (@@tep2)—. . (84+e42-1)75
where 4 is a whole number lefs than x a two or more, when
the fum of an infinite feries is required.
Affume for the fum the quantity (s+e)—. (2+e+ ry cene
(Sfpep2) (sheet a = 2) y (az? + Bh yh yelp &c.);
find the difference between this fum and. its fucceflive one
(wet Ori AS AVS! Cz ted 3)5" ae (s+etna— Tae
ise (ezt1 I Da. ati | Sos &c.), which will be —(z4+¢e)—.
Geet BSE Ae UE ating Sida ea a,
(as+1 I agate Pam a I teas -- S&C. ) ae a Cams
(=h —an+ tex + &e Ni; their make the terms, of this dit
ference equal to the correfpondent terms of the given quantity
az? + bz 4 &c. and there refult 2’ =h,—-h-n+1xa=a, and
Dyas ‘i
confequently «= a or 5 Bae
22, Let “the -veneral term ‘be « (e-fe)"* 2 @ eden)
(sfet2y—7...(2fet+u-1)7x@t+f/)7.@+ft+ i pag
(24 f+2)*... (2+ f+m—1)— x (az? + bz) 4 cz’* 4 &e.).
Affume the quantity (= +e)". (z+e+1)—...@@+e+n—2)>
x(2+f)—.. (2t+f+i)7 . (@4+f+2)".. (z+ f4+m-—2)7
x (ax +622 472° 4+ &c.) for the fa of the feries fought ;
and thence deduce the general term, which fuppofe equal to the
given general term, and from equating their correfponding parts
eafily can be deduced the index 4’ and co-efficients a, @, y, &e:.
and confequently the fum of the feries fought..
a. eee
392 | Dr. WariNne on the. !
3. Let the general term reduced to its lowett dimentions’be ‘i
Zoe gay mp ee SHEtu—I ee x PEAS EP st
———_——— : i a Oy TR ————
retfror >... retftm—ir Koto “x 2 oes ve ae
ope. oe ace x (az? ee a +&c.). If it be re-
quired to reduce the term rz + vee &c. torr sofort with
the reft, forrz+f °, & _paleoaeuee Bb i} ‘x4r-e, &c. and it
is. dene. .Affume for the integral ‘or * fie ‘the quantity
Saepessbebi .. ebetn—2 x reef \. ree Pap,
Pet m—art fox She XZ4Sh1 sy Spee ee
x (ae” + 0x’ + &c.) =S, find its fueceflive fum by writing
z+1:for sin the fum S, and let the quantity refulting be
S’; then will the general term be S—S’, which equate to the
given general term, that is, their correfpondent-quantities ;
and thence may be deduced the index 4’ and co-éfficients a, 6,
&c.; and confequently the fum fought. If the feries does not |
terminate, then the fum will be expreffed by a feries proceeding
in infinitum, according to the reciprocal dimenfions of 2.
From 2w+e+o+ &c. ~1 independent integrals of the
above-mentioned kind can be deduced the integrals of all quan-
tities of the fame. kind ; that is, where 4 is any whole affirma-
tive number whatever, and the co-efficients. a, 4, c, &c. are
any. how varied.
If any factor .z+g in the denominator, &c. has no ote
z-+g¢+/—1, which differs from it bya whole number/=13 or
the factor rz+.f has ne correfpondent factor rz +f-++ mr, where
mis a whole number; then -the integral of the above-mentioned
feries cannot be exprefled in finite terms of the quantity 2. In
like manner, if the dumenfions of z in the numerator are lefs ©
than
|
Summation of Sertes. 393
— its dimenfions in the denominator by unity, then the in-
tegral of the general term cannot be expretied by a finite alge-
braical function of x. If the number of terms to be added be
infinite, it is well known that the fum in this cafe will be
infinite.
‘ft may be obferved, that in finding the fum of a feries,
whofe general term is given, all common divifors of the nume-
rator and denominator mutt be rejected, otherwife feriefes may
appear difficult to be fummed, which are very eafy: for exam-
. : I 4 9 .
Ce be TPs 4k 5 0. 1 en H Oy Oe) EO) pte
2
# heat (144g dt Be), whofe
ZH.
general term is Se Tg A seh 2 ee S
; and by affuming, as
s before taught, 32+ Re ix 32+ 2 xa for the fum fought ;
and finding its general term 32+ 1 x 32+4 %3%+2. x!
32+5 x18%+4+1%xa, which equating to the general term
given, there refults 18a=1, and the fum fought = =
i8
I
B24+1. 3%+2-
he) Wetwthe fers be ol eee
Epa Ziv. Siskin 5 Sis Oe Pure ag
S5 140 Ligvan ae
9-10-11 Ee ieee) ie Sine a ae ve oes ae
I
a &c.), of which by general term is ; Be
—_—_—___ ; Ao confequently the fum deduced is — x’
ett. 4+ , : ae
i I
4 4241) | |
Thefe are feriefes given by Mr. De Moivre, and efteemed
by Dr. Tay tor altioris indaginis.
VoL. LXXIV. Ff £€ i Some
: ‘ | ;
394 Dr. Wanine on the , |
Some other writers have made fome feriefes to appear more
difficult to be fummed, by not reducing them to their loweft :
terms. 4
+, Having given the principles of a general method of find-
ing the fum of a feries, when its general term can be exprefled
by algebraical, and not exponential, functions of z, the dif-
tance from the firft term of the feries; it remains to perform
the fame when exponentials are inchided. :
1. Let S the fum be any algebraical function of 3 multi-
plied into e* =x* ; then will the general term be Se*7—eS’e#=
(S— eS’); whence, from the general term Te* being given,
affume quantities in the fame manher (with the fame denomi-
nator, &c.) as when no exponential was involved, which
multiplied into e%, fuppofe to be the fum; from the fum find
its general term, and equate it to the given one ‘by equating ©
their correfpondent co-efficients, and it is done.
Z+2
227-1. 2343
Ex. Let the general term be x e=tr: affume for.’
the fum fought x et1, whence the general ‘term is
x
2z24+1
r \e ary)
( ra om ) eases ae
x e*+1$ equate it to the
22-1 23 -+ 3 25-1... 2243
given term, and there refults 22 (1—-¢)=1 and 3a— oe = 2,
and confequently e=+ and a=, if the feries can be fummed.
The fame obfervation, vz. that if any fa€tor in the deno=
minator or irrational quantity have no other correfpondent to
it; for example, if the faCtor be 24+, and there as no ¢or-"
re{pondent one ¥+g+%, where n is a Whole number, then its
integral cannot be exprefled by a finite algebraical fun@ion
of z. |
In the fame manner may the fums be found, when the terms
are exponentials of fuperior orders; for the exponential, inra-.
6 tional,
| Summation of Series. “ays
tional, &c. quantities in the denominators of the fums may be
eafily deduced from the preceding principles; and thence, by
proceeding as is before taught, the fum required.
The principles of all thefe cafes have been given in the
Meditationes.
8. Mr. James Bernovrii1 found fummable feriefes by
affuming a feries V, whofe terms at an infinite diftance are
_ infinitely little, and fubtraéting the feries diminithed by any
number (/) of terms from the feries itfelf, &c.
It is obferved in the Meditationes, that if T (mm), Tl’ (m +n),
T(mtnta’), Timt+n+n' +n"), &e. be the terms at m,
m+nz, m+n+tn', mint+n +n", &c. diftances from the firft,
and aT (m)+4T (nn) eT (2 tu tn) + dT (m4n4n +
nm’) +c. be the general term, it will be fummable, when
a+6+c+d+&c,=0; the fum of the feries will be a(T(m) +T
(m+1)4+T (m+2)-- 2... +T (m+n+n't0"+&e.—1))
+O(T (may tT (mtntry)4T (mtn+2)+ ... +T
(m--n-en! +n! 4-&c.—1))- (Tn) +T(a+ntn’ +1)
- 2. (Tmstnta’ +n’ +&e.—1))+&e.=H. If the fum
a+btctd+é&c. be not=o, andthe feries T(m)+T(m-+r)
+T(m--2)+ &c. iz infinitum be a converging one=S, then
will the fum of the refulting feries be (4--61-c+d+&c.)
S=- (64+c4+d4+&c.) (T*™ 2... +7") = (c+d+4+ &c.)
aires Wott ea. (dt Bc. NC Lee et tt)
Fe &c.
8. 2. Let the feries V confift of terms, which have only one
fa€tor in the denominator, and its numerator=1; that is, let
the general term be ——, and the feries confequently
7Z
+e
Stat Sa +é&c.= V3; from the before-mentioned addition
b c wks
or fubtraction there follows ep tae Weert; 4 &ei=
F ff. aa"
396 | : Dr. W Aarne. on. the
on Ox bye (+ &e.
yete.rztrte.7e+2r+e.
number (N) of factors in the denominator diminithed by unity..
Byom a, 25.75. SG 7 and ¢ being § given, eafily can be acquired by
fimple equations, or known theorems, the required co-efficients .
a, b;.¢,,8c.. lf m=N —1 and « and a+-b+c+d+&c.=0,.
then the fum of the feries refulting will be finite,. é
.
Ro 3 where m is not greater than the: q
° T , é
3. If ‘the terms. of the fenes aftumeéd, = ee 7 ae
NE a RS
+ &c.. be alternately affirmative and negative; then.
ae Es. M=32 :
vathe: preceding) cafe find)" * "23 See a
by. the preceding ca dis Sp ee
b TT 1 4
: + +&c, Where the terms of the refult- -
robe repete rze+arhe
ing feries are alternately. affirmative and nee let the -
Be es a Tt ane op Seed .
TELE + Bb +E o a rey,
two fabfequent terms be fuppofed -
ee 1 RE. and amt E et ee ere: * a Sec,
is rh re4 re Tate. Ta Ta2r WHT. 5 ay
b
— Ft & ee. of which+the one is affirmative-and the
r2-+r-—-te | 2+ 2r-Fe
other Sitios : reduce the refulting feries to-an affirmative one
by fubtracting the fubfequent term from its preceding, and it be-.
, m B Sri. The ate
(rz -tur-pey (we Ox" +&c.)—(rz +e) (ext $RetE ke.)
rzFe. r2+7+e.7e parte... -7S+rn-+e -
Mm——T
comes
™ -
N— Mam + &e. be y e
ps, ae ee Maal tne ies 9 eS sap "
Tree. v2 p-rbe.refrate rZ-+e * aaa + ee In this
cafe, fince,two terms are added into one, the diftance from,the
ws - a z x 3
firft term of the feries will be —,..which fuppofe = w; and.write
2
2w for % in ‘the above-mentioned term, and: there refults
n— mraz +-&e. n—mra% 2” w+ &e,
tehe . rztrte.e 1Btmrte. wwe « 2wtrte... 27w+nurte
a
2rw He
Summation of Series 397
¥ pus A Bie
ie °~* _4 &c.; whence the fum of any feries, whofe
arw+e, “orw+r--e
™m + [—T :
w thw + &c. ‘
mae a er Oe ee berey mais
Qrwtre.2wt+rpe... Qrwtur+te
whole number lefs than x by two or more, and w the diftance
from the firft term-of the feries can be found from the fum of
general term is
° 3B, IT
Peete ES Se ae ct
é am Dre beat 4. G
g. Let:there: be two feriefes —+- Syd 4 oc, nS. aad,
e+r e+a2r
a T 7
& sign! Fea) Para tate ’, whofe general terms are re=
f{pectively Pas and = re ; then from the fum of thefe two
feriefes can be colleéted the fum of any feries, whofe general
term is
ee ae beac, '
re-eretetr.retet 2r...retn-irpexratf.retr+fe..1etfbm-ir
SL] ee ¢ a a’ bY
ca ee aay LOR Ur ald aia mega De eae ‘
cl i Ae a
——__.,, +-__#____; wheree — fis not awhole num-.
1B + 2r-+f ; rom ir fp" wher ae
ber. Leta+d+te.. ta=o, and a’+é’+c'...--wi=o, then:
ecmemile (tat aa
eee a at eee ee
Gems) 8! Aaa ary YER)
a= ae +e) he. |
2, If the feriefés are or ae “Tr li ie
“~ &c.: then from the fum of thefe two feriefes can be collected
by the principles given above the fam of any ee whofe
general term is
2, OZ.
398 | . Dr. Wanine on the
we Be Eb ye —2 41 Be, ing aia a
The fame principle may be applied to find the fum of any |
feries of the abovementioned fort, in whofe denominator are
contained other factors, ra+g, rz+g+r, &c. &c.5 or 2rz+g,
arzt+g+r, 2re+g¢+2r, bc. Like propofitions may be de-
duced from feriefes, in which r and 7’, &c. and the faGors
re+eand r’z+¢, &c. denote different quantities.
10. An apparently more general method may be given from
affluming a feries or feriefes as before ; and adding every two,
three, four, &c. (”) fucceflive terms together for terms of a
new feries beginning from the firft, fecond, third, &c. nh
term. and in general adding together two, three, &c. 2 fuc~
ceflive general terms; and in their {um writing for 2 the diftance
from the firft term ef the feries 2244, 3244, &c. we+a;3
there will refult the general term of a feries not to be found
from the above-mentioned addition. |
Ex. Let the feries aflumed be 14+43+23+4+1i1+&c. im injini-
tum, of which the general term beginning from the firft 1s
= add three fucceflive general terms a ee +o
> &
22 -L19Z+1I : : ,
= ERS e in this term for = write 32, and there
+3
292° + 362411
begining is inftituted from the fecond or third term of
32° + 182426
In the fame manner, if the
the given feries, the terms refulting will be
B39. St4- S+5
bofale 27% +5424 26 anette 47
and ——
3%+2 + 32+3 + 3344 3243+ 3244+ 3245
In thefe terms for % write 3%, and there
o
Summation of Series. 399
» Tf the terms of the given feries are alternately affirmative and.
negative, the terms of the refulting feries will be alternately
affirmative and negative, if #2 be an odd number; otherwife its
terms will be all affirmative. The fum of this feries will be
finite or infinite, as the fum of the feries r+ $ +2414 &c. is.
finite or infinite; but from it, by the preceding method of addi-
tion or fubtraction of Mr. BerNouLti’s, ora like method applied.
to more feriefes, may be found the fums of different finite feriefes,
It may be obferved,, that from Mr. BeRNouLti’s. addition or
fubtraGiion can never be deduced the feriefes which. arife from
this method; for, by his. method, the denominator can: never
have any fators but what are contained in the denominators of
the given feries, viz. (in the feries 3+ $+2+ &c.),%+/ where.
Zis a whole number;. but by this.method are introduced into.
the denominator the factors. 22+/, 3z+4/, &c..and 7z+/, or-
which may be reduced to the fame (= + - ) x Me.
If x fucceflive general terms of the feriefes arifing from Mr. .
BeERNOULLI’s addition or fubtraCtion be added together, and in.
the quantity thence arifing for = the diftance from the firft-
term of the feries be fubftituted mz, there will be produced:
feriefes of the above-mentioned. formula.
11. Multiply two converging feriefes.a +. bx + 0x? + de? + &e..
=S and 4+ 0r+ 9x +&c.=V, or find any rational and inte--
gral function of them, and the feries. refulting will be finite- |
and=SxV, &c. Let.e+ Cr+ 704+ &c. x"=V be finite, and.
the refulting feries. will be finite and=5.x V, &c.. If S be a
feries converging or not, whofe ultimate terms are lefs than,
any finite quantity, then will the feries (¢+6x+0¢x° + &c.) x
fa-t Px + ya" + &c.x”) = V x S be a converging one, if «+ Gx +.
y+... cc. x"=.0; which cafe was given by Mr. De Moivre.
Mr.
#00 | Dr. Warinc on the 4 . |
Mr. Berwou.ir’ s addition, &e. can be applied to. feriefes‘of
ai
this cat F or example, let the given feries be 2 oe at,
a «+ &c.=8. From:this feries ‘fubtraat the Woe feries di-
2 : Te I I : oe
minifhed: by m:-terms, 072, —— x" 4 gt
wis i é-+m MEGA Basti ati
1. &c. and there..rcmains:, “0 4 ee
.-é@. m-be Ob cebpmep ors
pes Miz 7 Pear ee ™ 4 f fe M
ii eh aang eh a ed ak aaa x 0° 8c. for x” ‘write A,
e+2.e+-m+2 e+3 .¢+m+3 ;
then will the feries become “224. chmbinepia ae fe}
-m+e Pris oot a
ebmr2—et2A 2 ides w+ &. = - =f er,
é+2.¢+m-+-2 e+3 -etm+ 3 e+
pri x oe @ @ OED Fo
é+2 eé+m—I
mtb eee, epee
Let the ral erm be DN get Ei. Eee as oe
h tga : SteeSteti.zZfet2..S+etu—i
7. og bite Me spre b Lps: ze § /
= (4+ 4+ +’) x*. Suppofe @ = er,
yi Xs O-0k, «- &= Xa? s then. will the tum) ofieme
above-mentioned feries be (#+’ + y +0 + &c.) x S-=
/ Za Ys youl ,
(C 18's +0 + &c.) nan (> +0 ar:
by thefe
From the ‘fum of the “feries 1 —
é ae e+
and the principles before delivered can be deduced the
fum of any feries, w hofe general term 1s
ax” tho” "4+&e. oy
2B-+e. 2Z+e+ 1. 22+e42. 224Fe43X &K,
3
In like manner from the fum of the feriefes * a +2 rea
ec
, 6 0h Pe ve?
fen oe ee Ste &c. can be
J I) ease &t+i gt2
deduced
Summation of Series. 401
deduced the fum of any feries, whofe general term is
az bee ae Bee,
Bpeetep ic bepaMbeket fat fti.etft2.Rexet gate pike
[we e*
And alfo from the fum of the feriefes 1 _—"-» 4 “—- &c.
eC invetak e+2
x” I 2 4
eer ic. 2) ie. ace! be deduced
7 eee ria &c : aes &c. &c. can be deduce
the fum of any feries, whofe general term is
ax bz" 4 &e.
Qz-e. 2zte+1 .&c.xaztf.oz+f+1.&c.2z+g.9z+g+i. &c.
The method of adding more terms of a given feries toge-
ther, as before taught, may be applied to thefe and all other
feriefes. For example: let the given feries be 14+3¥+4%"
+ 4x° + &c.; add twotermsconftantly together, and it becomes
Riess
2 A 2A Bee
peer &c a a, et &ces celia Guna es) +.
2 ey 5° 2, Bid
GSA - az+2+(22+4 1)
= +&c. whence the general term is se
rare From the methods before given of addition, fub-
traction, and multiplication ; and the feriefes found by this
method, can be derived feriefes, whofe fums are known.
12. Suppofe a given feries ax" -+ burt: + curt + devts + &c.
whofe fum # is either an algebraical, exponential, or fluential
fluxion of x; multiply the equation pa axt + bart + cx +
darts 4 8c. into wt *,andthererefults avt—"p = ant” 4 bab +
ext 4 &c.; find the fluxion of this equation, and there
follows — multiplied into the fluxion of the quantity (xt—"9)
a
= traxtar4 (sorchs) bx 4 (sere 2s) cbt + &e.
of which the general term is (=r=:%s) x ft, where = denotes
the diftance from the firft term of the feries, and ¢
You. LXXIV. Gegeg eas
402 Dr. Warine on the
is the term inthe given feries, whofe dienes from the ff
is z. Inthe fame manner may be deduced the fum of a feries,. 4
whofe general term is fx soranzsx 7’ -s-ns, or by re-
peated operations 7’ x ex" -+-fe+g, where ¢’ is a term of the |
given equation, whofe diftance from the firft term 1s 2. And
_ in general, from the fum of a given feries, whofe fluxion can.
be found, and whofe general term 1s #’, can be deduced by con- ;
tinued multiplication, and finding the fluxion, the fum of a
feries or quantity, of which the general term is A”, where A)
is any function of the following kind a’2” 4-6’2"—" 4 clam 4. &c.
in which z denotes the diftance from the firft term of the feries,,
and mawhole number. It isto be obferved, that if the given.
feries converges in a ratio, which 1s at leaft equal to. the ratio:
of the convergency of fome geometrical feries, the refulting
equation will always converge. But if in a lefs ratio, then
it will fometimes converge, fometimes not, according to the
ratio which the fucceflive terms of the refulting feries have
to each other at an infinite diftance.
Cnilarys 2 Bea sai Boni o. Bee ees
8, YToPPEL AX EQ er Howe OPIS
PES. PRT. PRS 25 PHSTP 2 Zr. aol ee i r
PS PET . TPS eR ee p-I » if pr bein wiole
affirmative number; but this latter quantity has the formula;
above-mentioned az” + 4z"-* +cz"-3 + &c. ; and confequently,.
if the fum of the feries a+ dx + cx + dv3' + &c. =p be known,.
by this method can be deduced the fum of the feries)
a2 by pie 1 t oxtt B Pett? dst 4 &e. | 4
: le ae ix Oe |
Ex.1.Sincea +x" =a (142x243 xB 7 ait } a
m—2n
4
a-2x° +&c.); multiply the fucceflive terms bf this feries
inte
x:
Summation of Series. 493
of
into the terms of the feries 1, ee ie paPel, &c. and a feries is
‘ aie
um m ny
Dene acme ae prptixm.m—n Nig ear
deduced a +-——a Cane Sata eet + &c.
ut
e ° ° ——+— .
whofe fum is known, if the fum of the feries=a+% 7 is
known.
Ex. 2. If the feries begins from the /41" term of the above-
s é : MB Ap ie 3
mentioned binomial theorem a — as ae "x+&c. viz. the
m—1+1 m—l+2 x] 3
re be es a ee
l+2n @ l+3n a l+4n a3
ef which let the refpeftive terms be multiplied into 1,
£ s at » &c. there will refult a feries whofe fum is known.
Tease
Ex. 3. From the rule firft given by me for finding the fum of
the terms at 4 diftances from each other, the fum of the feries
pa Mate y mal an i m—ie hn x + Pox mak b+tn
l+2.H# l+3n at GP l+h+an
ihe We 2 rE 2 m--lf2hns Be, where P denotes the co-effie
t+h+3n /+2h+ in a
cient of the preceding term, can be deduced; and confequently
‘the fum of the feries deduced from multiplying the fucceffive
A G A aire Dp I
terms of this feries into the quantities 1, t,t ue pei, &c. res
fpectively.
The general principles of this cafe wete firft delivered by
Mr. Berznoutti, Mr. De Moivre, Mr. Evier, &c.
12. Affume the feries a4 + bx” 4- cx?” + &c. =f, multiply it into
wx, and find the fluent, thei will : up — : fv = : axe +
| Ggeg2 f
£O4 Dr. Warine on the
ss olaree abn pon as Z thi . : 7 «oe
a — bye + &c.; multiply this equation int )
re A And the fluent of the equation refulting, whic
/
will be : x : “eh — = ee - Se %
[tint ford, ime pee oe
divide by +°, and there refults = a ~ p+- : == i +
z mn) oe : cs oe a : and in gene=
ral 5° x Sepa == eo focp ee are ;
ke fxip+ 2 222, Bel 2 [e; 1 Bc key
Oh . == == &c. bx" + : poe ae ore &c. cx” 8c.
whence the law of continuation is immediately manifeft.
Hence, if no two quantities a, 0, y, 4, &&c.. be equal to each:
other; and the fucceflive terms a, 4, c, d, &c. of any feries.
a+ bx" + cx" + &c. = pbe divided by «8. y.d.&c.3¢+n. Btn,
ytn. d+n.&c.3 at22.C+2n.y+2n.d3+ an. &e: &e.s
and in general by a+mz.B+nz.y+nz,d+ne. &e. &es.
then can the fum of the feries be found from the fluents of the
fluxions «A, «°f, »p, xp, &c. as has been obferved in the:
Meditationes. If two are equal, wiz. a=, then. alfo the
fluent of the fluxion * [vp is required. If three are equal:
viz. c= R=y; thenit isneceflary to find the fluent of the fluxion:
wn a and. fo on..
i. Letp= eres ; and if the differences of the quantities a,.
iUS=h 5
& y, 0, &c. are divifible by w,. from the fluent of the:
-fluxion.
Summation of Series. 405
fluxion **f can be deduced the fluents of all the other fluxions
xp, xD, &c.; and in general, if «— is divifible by,n, then
from the fluent of the fluxion +f can be deduced the fluent of
the fluxion +%6.
z. Suppofe f = the terms of the binomial theorem ex-
panded according to the dimentfions of x, wx. (4+ dx") - =
att - as "bxt + &ce. beginning from the firft or any other
terms; then, if a, @, &c. divided by ~ give whole affirmative.
numbers, will all the fluxions +f, x°6, pf, &c. be integrable ;
and if the differences of the quantities «, @, y, 5, &c. are divi-
fible by x, from the fluent of the fluxion «xf can be deduced
the fluents of the fluxions +*f, wf, &c.
If p denotes the fum of the alternate or terms whofe diftance
from each other are m, of the binomial theorem, the fame:
may be applied..
3. If p=a+bx+cx"*; and a, B, y, 4, &c. divided by #
give whole affirmative numbers, then from fp can be de=.
duced all the remainder i xp, fi xp, &cc.: and in general from:
two can be deduced all the remainder.
To find when the fum of any feries of this kind can be
found, add together each of the fluents, which can be found
from each other, and not otherwife, and fuppofe their fum =o ;
and fo of any other fimilar fluent, and from the refulting
equations can be difcovered when the feries can be integrated.
13. If the general term of a feries contains in it more: va=.
riable quantities, z, v, w, &c.; then find the fum of the feries,.
firft,, from.the hypothefis that one of them (%)-is only varia-.
bles.
406 — Dr. Warine on the ga ,
ble, which, properly corrected, let be A; in the quantity A
fuppofe all the quantities invariable but fome other v, and find
the fum of the feries thence refulting, which let be B, and fo
on; and the fum of the feries will be deduced.
: I 2h a
Ex. Let the term be 2st oe en eee? the dimenfions |
of z and v, &c. in the denominator muft be at leaft greater
than its dimenfions in the numerator by a quantity greater
than the number of the quantities %, v, &c. which proceed
in infinitum increafed by unity. Firft, fuppofe = only
variable, and the fum of the infinite feries refulting will be
it
BZGevuev+i1.v+2
= A; then fuppofe v only variable, and the fum
refulting will be = : == B, which is the fum required.
If it be fuppofed, that the quantities z and v, &c. in the
fame term fhall never have the fame values, then fuppofe
z and v always to have the fame values, and the general term
I I e
—__—___- = hecomes ——_—_—-——, of, whieh erie
Be Zt VU. v-+1 ~ U+2 ieee F - 2+2 :
fum be V, then will B = V bethe fum required. |
On this and fome other fubje€ts more have been given in the
Meditationes. |
14. If the fum of the feries cannot be found in finite terms,
and it is neceflary to recur to infinite feries; it is obferved in
the Meditationes to be generally neceflary to add fo many
terms together, that the diftance from the firft term of the
{eries may confiderably exceed the greateft root of an equation 7
refulting from the general term made=o; and afterwards a7
{eries more converging may commonly be deduced from
the fluents of fluxions refulting from neglecting all but the
greateft quantities in the general terms refulting ; and by other
2 different —
Summation of Series. | 407
différent methods. Mr. Nicoias Bernovixr and Mr. Mom-
MoRT invefligated the fum of the feries (P) A+Br4Cr+
ih Ug? "
@e. Hy a feries 4 ): — et ep etek s
where d’, d”, d’”’, &c. denote the fucceflive differences of
the terms A, B, C, D, &c. If r be negative, the denomi-
nators become +7, (1+7), (1+7)’, &c.
It has been. obferved, in the Meditationes, that in fwift con-
verging feries. the feries P will converge more fwiftly than the
feries Q ; in feries converging according to a geometrical ratio,
fometimes the one will converge more {wift, and fometimes
the other. Jn other feries, which converge more flow, where
moft commonly 7 nearly=1, it cannot in general be faid,
which of the fericfes will converge the {wifteft. The preceding
remark, viz. the addition of the firftterms of the feries, is ne-
ceflary in moft cafes. of finding the fums by {feriefes of this.
kind.
It is not unworthy of obfervation, that in almoft all cafes of
infinite feries, the convergency depends on the roots of the
given equations, which remark was firft publifhed in the Me-
ditationes. For example: in finding approximates to the roots
of given equations the convergency depends on how much the:
approximates given are more near to one root than to any
other ; and confequently, when two or more roots or values of ~
an unknown quantity are nearly equal, different rules are to be
applied, which are improvements of the rule of falfe.. This.
rule, and the above-mentioned obfervations were firft given in the
Meditationes Algebraic et Analytica, with. feveral other:
additions on fimilar fubjects..
Many
408 Dr. Wanine on the
‘Many more things concerning the f{ummation of feries, which _
‘depend on fluxional, &c. equations, might be added;. but i
fhall conclude this paper with congratulating myfelf, that fome
algebraical inventions publifhed by me have been fince
thought not unworthy of being publifhed by fome of the
ee mathematicians of this or any other age. |
1ft, In the year 1757, I fent to the Royal Society the firft
edition of my Meditationes Algebraicze: they were printed and
publithed in the years 1760 and 1762, with Properties of Curve
Lines, under the title of Mifcellanea Analytica, and a copy
of them fent to Mr. EuLer in the beginning of the year 1763,
in which was contained a refolution of algebraical equations,
not inferior, on account of its generality and facility, to any
yet publithed (viz. y=a W/p+d V/p te Vp +../p). This
refolution was publifhed by Mr. Ever in the Peterfburg A&ts
for the year 1764. Whether Mr. Ev_er ever received my
book, I cannot pretend to fay ; nor is it material: for the fact
is, that it was publifhed by me in the year 1760 and 1762,
and firft by Mr. EvLer in the year 1764. Mr. DELA GRANGE
and Mr. Bezout have afcribed this refolution to Mr. EuLer, as
firft publifhed in the year 1764, not having feen (I fuppofe)
my Mifcell. Analyt. .Mr. Brzovr found from it fome new
equations, of which the refolution is known, and applied it to
the reduction of equations: more new equations aré given,
and the refolution rendered more eafy by me in the Philofophi-
cal Tranfations. 2d, In the above-mentioned Mifcell. Ana-
lyt. an equation is transformed into another, of which the
roots are the fquares of the differences of the roots of the
given equation; and it is aflerted in that book, that if the
coeefficients
Summation of Series. 469
co-efficients of the terms of the refulting equations ch ange con-
tinually from + to — and — to4, the roots of the given equation
are all poffible, otherwife not; and in a paper, inferted by me in
the Philofophical TranfaCtions for the year 1764, in which is
found from this transformation, when there are none, two or
four impoflible roots contained in an algebraical equation of
four or five dimenfions; it 1s obferved, that there will be none
or four, &c. impoffible roots contained in the given equation,
if the laft term be + or —; and two, &c. on the contrary, if
the laft term be = or +. Thefe obfervations and _ tranf-
formation have been fince publifhed and explained in the Berlin
Ads forthe years 1767 and 1768, by Mr. pp La Grance. 3d.
In the Mifcell. Anal. an equation is transformed into another,
whofe roots are the fquares, &c. of the roots of a given equation ;
and it is aflerted, that there are at leaft fo many impoflible roots
contained in the given equation, as there are continual pro-=
erefles in the refulting equation from + to + and ~to-. It is
afterwards remarked, that thefe rules fometimes find impoffible
roots when Sir Isaac NewrTon’s, and fuch like rules, fail; and
that Sir Isaac NewrTon’s, &c. will find them, when this rule
fails. This rule may fomewhat further be promoted by firft
changing the given equation, whofe root is “, into another
whofe root is /—1%*3 but, in my opinion, the rule of Har-
RioT’s, which only finds whether there are impoffible roots
contained in a cubic equation or not, 1s to be preferred to thefe
rules, which, in equations of any dimenfions, of which the
impoffible roots cannot generally be found from the rules, {e]-
dom find the true number. 4th, It is remarked, that rules
which difcover the true number of impoffible roots require
immenfe calculations, fince they muft neceffarily find, when
mou. LXXI1V. Hhh the
w
410 Dr. WaRING on the — ati
the roots become equal. In order to this, in the Mifcell. Anal.
there is found an equation, whofe roots are the reciprocals of
the differences of any two roots of the given equation; and -
from finding a quantity (7) greater than the greateft root of the
given, and ( x) greater than the greateft root of the refulting .
equation, and fubftituting <, c—A, 7—2A, &c. for x» in
the given equation ; will always be found the true number
of impoflible roots. . 5th, In the fame book are affumed two
equations (nx — 1px"*-4+n—29x"-3 — &e. =o and]
x" — px"—' + &c. =w), and thence deduced an equation, whofe
root is w, from which, in fome cafes, can be found the num-
ber of impoffible roots.
6. In the Mifcell. Anal. is given the law of a feries, and its
demonttration, which finds the fum of the powers of the reots
of a given equation from its co-efficients. Mr. Evier has fince
publifhed the fame in the Peterfburg Acts. Mr. pp La GRANGE
printed a property of this feries, alfo printed by me about the.
fame time; v/z. that if the feries was continued 7 imfinitum,
the powers would obferve the fame law as the roots, which
indeed immediately follows from the feries itfelf; but from
thence with the greateft fagacity he deduces the law of the
reverfion of the feries (y=a+6x +cx* + dx’ +&c.): it has fince
been given in a different manner from fimilar principles in the
Medit. Analyt. 7. In the Mifcell. Analyt. the law of a feries
is given for finding the fum of all quantities of this kind (a x
Q" x y' x dx &c. + &c.) where a, 2, y, 3, &c. denote the roots of a
given equation, from the powersof the rootsof the given equation.
This law, with a different notation, has been fince publifhed in the
Paris A@s by Mr. VANDERMONDE; who indeed mentions that he
3 had
Summation of Series. Ali
had heard, that a feries for that purpofe was contained in my
book, but had not feen it. In the fame book is given a method
of finding the aggregates of any algebraical functions of each of |
the roots of given equations, which is fomewhat improved
in the latter editions. 8. In the fame book are aflumed
ge ond Set AE ees where % is any rational
pe tage” ' 4c. pz gz 7 +&c.
quantity whatever for + andy, the unknown quantities of a given
equation of two or more dimenfions. g. In the Mifcell. Analyt.
_a biquadratic (4°+2p=9x°+rx+s5, of which no term
is deftroyed) is reduced to a quadratic (# + px t+nu=
JP +antgxtVstn’ 3) and in the fecond edition of it,
printed in the years 1767, 1768, 1769, and publifhed in the
beginning of the year 1770, the values of # are found
B+yd h) b)
& 2s iad aide
Z4 2, 2
; and the fix values of Wy +2n+q
es ge) ees
refpeciively =——, — —— and their nega-
ab—yd ay—Bo
Pais ?
tives; and the fix values of /s+n° refpectively —— ;
oe and their negatives. 10. From a given biquadratic
(+9 +ry+5=0) by affluming y°+ay+=v and @ and 4
fuch quantities as to make the fecond and fourth terms of
the refulting equations to vanifh, there refults an equation
(v'+Av°+B=0) of the formula of a quadratic. Mr. pELA
Grance has afcribed this refolution to Mr. T’scHIRNHAUSEN ;
but in the Leipfic A&ts the refolution of a cubic is given by
Mr. T'scHIRNHAUSEN, but not of a biquadratic: his general
defign feems to be the extermination of all the terms.
Hhhz2 anes Mir.
om - Dr. WARING on the,
ir. Mr. Evver or Mr. pE 1A Grance found, that if @ bea
root of the equation x"— 1=0, where # is 4 prime number, ©
a, 27, a5 +. a'—', 1 will be (7) roots of it. More gaya aime
lar fabject has been added in the laft edition of the Medit.
Alsebr..) 12.1 Tt is obferved in the Mifcell. Analyt. that
‘Carpan’sor Scipio FERREUvS’s refolution of a cubic 1s a refo-
lution of three different cubic equations; and in the Medit.
Algeb. 1770, the three cubics are given, and the rationale of
the refolution (for example: Wa, G, and y, be the roots orm
the cubic equation «+gx—r=o, then is given the function
of the above roots, which are the roots of the reducing equa-
tion 8° —rz°=q°); and alfo the rationale of the common refo-
lution of biquadratics. 13. It is aflerted in the Mifcell. that
if the terms (My"+ dy"7v +:cy"*x" + &c. and Ny”+ By*—ty 4 |
Cy”—2x° + &c.) of two equations of ” and m dimenfions, which
contain the greateft dimenfions of * and y have a common di-
vifor, the equation whofe root 1s « or y, will not afcend to
a xm dimenfions; and if the equation, whofe root is x or y,
afcends to mx m dimenfions, the fum of its reots depends on
the terms of m and ~—1 dimenfions in the one, and m and
m—1 dimenfions in the other equation, &c. It is alfo afferted,
in the Mifcell. that if three algebraical equations of », m,
and y dimentions contain three unknown quantities «, y, and .
z, the equation, whofe root is x ory or %, cannot aftend to
more than 2.m.rdimenfions. 14. Mr. Bezour has given
two very elegant propofitions for findmg the dimenfions of the
equation whofe root is x or y, &c ; where x, y, &c. are une
known quantities contained in two or more (4) algebraical
equations of =, e, c, &c. dimenfions, and in which fome of
the unknown quantities do not afcend to the above z, p, o, &c.
dimenfions
.
Summation of Series. 413
dimenfions refpectively. In demonftrating thefe propofitions
he ufes one (amongft others) before given by me (a7. if an
equation of # dimenfions contains m unknown quantities, the
number of different terms which may be contained in it will
So Se =) . Inthe Medit. 1770 there is
2 3 m
given a method of finding in many cafes the dimenfions of the
equation, whofe root is x or y, &c.; from which one, if not
bew+1..
both, of the above-mentioned cafes may more eafily be deduced,
and others added. 15. In the Medit. 1570 is obferved, that
if there be # equations containing m unknown quantities,
where z is greater than m, there will be 2—m equations of
conditions, &c. 16. In the Mifcell. 1s given and demon-
{trated the fubfequent propofition; wx. if two equations con-
tain two unknown quantities » and y, in which « and y are
fimilarly involved; the equation, whofe root is x or y will
have twice the number of roots which the equation, whofe
root is x+y, «°+y, &c. has. In the Medit. 1770 the fame
reafoning is applied to equations, which have two, three, four,
&c. quantities fimilarly involved. 17. Mr. pe LA Grance has
done me the honour to demontftrate my method of finding the
number of affirmative and negative roots contained in a biqua-
dratic equation. A demonftration of my rule for finding the
number of affirmative, negative, and impoflible roots contained
in the equation x”+ Ax"+B=01s alfo omitted, on account of its
eafe and length. From the Medit. the inveftigation of finding the
true number of affirmative and negative roots appearsto be as diffi-
eult-a problem as the finding the true number of impoflible roots 5
and it further appears, that the common methods in both cafes
can feldom be depended on. But their faults lie on different fides,
4 the
Ald "Dre WARING On the) i
the one generally finds too many, the other too few. 18. In
the Medit. 1770, from the number of impoffible roots in a
given equation («" — pe + &c. =0) is found the number of im-
poffible roots in an equation, whofe roots (v) have any afi igna-
ble relation to the roots of a given equation; and examples
are given in the relation (nxt — n= 1px’ + &e. =U) 3 amd
in an equation, whofe roots are the fquares of the dif-
ferences of the roots of the given equation. 19. It is obferved
in the Medit. 1770, that in two or more equations, having
two or more unknown quantities, the fame irrationality will be
contained in the correfpondent values of each of the unknown
quantities, unlefs two or more values of one of them are
equal, &c. The fame obfervation is alfo applied to the co-
efficients of an equation deduced from a given equation. 20.
In the Mifcell. was publifhed a new method of exterminating,
from a given equation, irrational quantities, by finding the
the multipliers, which, multiplied into it, give a rational pro-
duct. 21. In the Medit. 1770, are given the different refolu-
tions of a certain quantity (2° + rd*)*"t" and (a* +7ré°)*"+ into
quantities of the fame kind. 22. Mr. pe La GRANGE has very
elegantly demonftrated Mr. Wixson’s celebrated property of
prime numbers contained in my book. In the laft edition of the
Medit. the fame property is demonftrated, and fome fimilar
ones added. 23. In the Mifcell. is given a method of finding
all the integral correfpondent values of the unknown quantities
of a given fimple equation, having two or more unknown
quantities ; and, in the Medit. 1770, are given methods of re-
ducing fimple and other algebraical equations into one, fo that
fome unknown quantities may be exterminated; and if the
unknown quantities of the refulting equations be integral or
a rational,
Summation of Series. 415
rational, the unknown quantities exterminated may alfo be
integral or rational. 24. In thé Medit. are given rules for
finding the different and correfpondent roots of an equation,
whofe refolution is given. 25. Mr. DE LA GRANGE has recom-
mended my new transformation of equations, publifhed in the
Mifcell. which perhaps is not lefs general nor elegant than any
yet publifhed ; and in the Meditat. 1770 is given a method very
ufeful in finding the co-efficients.
If either here, or in the preface to the Medit. Algebraice,
T have afcribed to myfelf any algebraical, or in the properties
of curve lines any geometrical, or in the Medit. Analyt. any
analytical invention, which has been before publifhed by any
other perfon, I can only plead ignorance of it, and fhall on
the very firft conviction acknowledge it.
I muft further add, that I have been able to carry my alge-
braical improvements into geometry; for from them, with
fome geometrical principles added, I have (unlefs I am de-
ceived) deduced as many new properties of conic fections and
curve lines as have been publifhed by any one fince the great
geometrician APOLLONIUS.
Bae]
AXIX. oe Account of a remarkable Froft on the 23d of June,
1783. In a Letter from the Rev. Sir John Cullum, Bart.
FR. S, and §. A. to Sir Jofeph Banks, Bart. P. R. S.
Read May 27, 1784.
Se te pie
WEEN Thad the pleafure of feeing you in London, in
the autumn, and mentioned a froft that happened in
my neighbourhood on the 23d of laft June, you expreffed a
defire of receiving fome particulars about it. I therefore now
fend you fome memorandums which I made at the time.
About fix o’clock, that morning, I obferved the air very
much condenfed in my chamber-window; and, upon getting
up, was informed by a tenant, who lives clofe to my houfe,
that finding himfelf cold in bed, about three o’clock in the
morning, he looked out at his window, and to his great fur-
prife faw the ground covered with a white froft: and I was
afterwards aflured, upon indubitable authority, that two men
at Barton, about three miles off, faw between three and four
o'clock that morning, in fome fhallow tubs, ice of the thick-
nefs of a crown-piece, and which was not melted before fix.
This unfeafonable froft produced fome remarkable effects.
The arifta of the barley, which was coming into ear, became
brown and withered at their extremities, as did the leaves of
the oats; the rye had the appearance of being mildewed; fo
that
Sir JouN Cuttum's Account of a remarkable Frof. 447
that the farmers were alarmed for thofe crops. ‘The wheat
was not much affected. The larch, Weymouth pine, and”
hardy Scotch fir, had the tips of their leaves withered ; the
firft was particularly damaged, and made a fhabby appearance
the reft of the fummer. The leaves of fome afhes, very
much fhelteredin my garden, fuffered greatly. A walnut-tree
received a fecond fhock (the firft was from a fevere froft on the
26th of May) which completed the ruin of its crop. Cherry-
trees, a ftandard peach-tree, filbert and hafel-nut-trees, fhed
their leaves plentifully, and littered the walks as in autumn.
The barberry-bufh was extremely pinched, as well as the hy-
pericum perforatum and hirfutum: as the two laft are folfti-
tial, and rather delicate plants, I wondered the lefs at their
fenfibility; but was much furprifed to find, that the vernal
black-thorn and {weet violet, the leaves of which one would
have thought muft have acquired a perfect firmnefs and
ftrength, were injured full as much. All thefe vegetables ap-
peared exactly as if a fire had been lighted near them, that had
fhrivelled and difcoloured their leaves :
penetrabile frigus adurit.
At the time this havock was made among fome of our hardy
natives, the exotic mulberry-tree was very little affected; a
fig-tree, againft a north-weft wall, remained unhurt, as well
as the vine, on the other fide, though juft coming into bloflom.
I fpeak of my own garden, which is high; for in the low
ones about Bury, that is but a mile off, the fig-trees, in pat-
ticular, were very much cut: and, in general, all thofe gar-
dens fuffer more by froft than mine.
Some weather, that was cold for the time of year, had pre-
ceded this froft. On the 21ft the thermometer had, at no
time of the day, rifen to 60°; on the 22d, at ten at night, it
Vow. LXXIV. ris had
Ae Aa AUPE ia
418 Sir Joun Cutnum’s Account of a remarkable Froft.
had funk to 50% On the laft day, and on the 234, difappeared’
that dry haze, which had taken place fome days before, and
continued to blot out the face of the fun for fo long a time
afterwards, After fun-fet on the 24th it appeared again, and:
the next day the leaves of many eae were covered 0"
a clammy f{weetnefs. LOW
The above flight notes were taken in my garden and its en=
virons; and I wifh they may afford you the fmalleft enter-
tainment. If you fhould think them worth the attention off
the Royal Society, difpofe of them accordingly. So fevere a’
froft, at fo advanced a feafon, is certainly not one of the leaft
remarkable among the atmofpherical: phenomena of this year.’
I remain, dear Sir,
Your much obliged and faithful fervant,
JOHN CULLUM,
edt. Jat? tt
XXX. On a new Method of preparing a Teft Liguor to foew the
_Prefence of Acids and Alkalses in chemical Mixtures. By Mr.
_ James Watt, Engineer ; communicated by Sir Jofeph Banks,
Y Bore, ER. 4S.
| Read May 27, ane
HE fyrop of violets was formerly the teft of the point of
{aturation of mixtures of acids and alkalies, which was
principally ufed; but fince the late improvements in chemiftry |
it has been found not to be fufficiently accurate, and the infu-
fion of tournefol, or of an artificial preparation called litmus,
have been fubftituted in the place of it.
_ The infufion of litmus is blue, and becomes. red ‘tiie acids. .
It is fenfible to. the prefence of one grain of common oil of
vitriol, though it be mixed with, roo000, grains of water ;
but as this infufion does not change its colour on being mixed
with alkaline liquors, in order to difcover whether a liquor be
neutral or alkaline, it is neceflary to add fome vinegar to the
litmus, fo as juft to turn the infufion red, which will then be
reftored to its blue colour, by being mixed with any alkaline
liquor. The blue infution of litmus is alfo a teft of the pre-
- fence of fixed air in water, with which it turns red, as it does
with other acids. |
_ The great degree of fenfibility of this teft would leave very
little reafon to fearch for any other, were there reafon to be-
lieve that it is always a teft of the exact point of faturation of
Pitz acids
F od
420 Mr. Wart’s Method of preparing
acids and alkalies, which the following fact feems to alls in
queftion.
I have obferved, that a mixture of phlositicasat nitrous
acid with an alkali will appear to be acid, by the teft of lit-
mus, when other tefts, fuch as the infufion of the petals of
the fearlet rofe, of the blue iris, of violets, and of other
flowers, will fhew the fame liquor to be alkaline, by turning
green fo very evidently as to leave no doubt.
At the time I made this difcovery, the fcarlet rofes and
feveral other flowers, whofe petals change their colour by acids
and alkalies, were in flower. JI {tained paper with their juices,
and found that it was not affected by the phlogifticated nitrous:
acid, except in fo far as it acted the part of a neutralizing acid ;
but I found alfo, that paper, {tained in this manner, was by no
means fo eafily affeted by acids of any kind as litmus was,
and that in a fhort time it loft much of that degree of fenfibi-
lity it poffefled. Having occafion in winter to repeat fome ex-
periments, in which the phlogifticated nitrovs acid was con-
cerned, I found my ftained paper almoft ufelefs. I was, there--
fore, obliged to fearch for fome fubftitute among the few vege-’
tables which then exifted in a growing ftate; of thefe I found
the red cabbage (braffica rubra) to furnith the beft teft, and in’
its frefh ftate to have more fenfibility both to acids and alkalies’
than litmus, and to afford a more decifive teft, from its being
naturally blue, turning green with alkalies, and red with acids ;
to which is joined the advantage of its not being affected by
phlogifticated nitrous acid any farther than it acts as a real acid.
To extract the colouring matter, take thofe leaves of the cab’
bage, which are frefheft, and have moft colour; cut out the
larger ftems, and mince the thin parts of the leaves very {mall ;
then digeft them in water, about the heat of 120 degrees, for
a few
”
4
~
J
a Tef Liquor for Acids and Alkalies. hy Bae
a few hours, and they will yield a blue liquor, which, if ufed
immediately as a teft, will be found to poffefs great fenfibility.
But, as this liquor is very fubjeé& to turn acid and putrid, and
to lofe its fenfibility, when it is wanted to be preferved for
future ufe the following proceffes fucceed the beft.
1. After havx.z minced the leaves, {pread them on paper,
and dry them in a gentle heat; when perfectly dry, put them
up in glafs bottles well corked; and when you want to ufe
them, acidulate fome water with vitriolic acid, and digeft, or
infufe, the dry leaves in it until they give out their colour;
then ftrain the liquor through a cloth, and add to it a quan-
tity of fine whiting or chalk, ftirring it frequently until it
becomes of a true blue colour, neither inchning to green nor
purple; as foon as you perceive that it has acquired this colour,
filter it immediately, otherwife it will become greenifh by
longer ftanding on the whiting.
This liquor will depofite a {mall quantity of gypfum, and
by the addition of a little fpirit of wine will keep good for’
fome days, after which it will become a little putrid and red-
difh. If too much fpirit is added, it deftroys the colour. If
the liquor is wanted to be kept longer, it may be neutralized by
means of a fixed alkali inftead of chalk.
2. But as none of thefe means will preferve the hquor lone
without requiring to be neutralized afrefh, juft before it is ufed ;
and as the putrid and acid fermentation which it undergoes, and
perhaps the alkalies or fptrit of wine mixed with it, feem to:
lefien. its fenfibility; in order to preferve its virtues while it is.
kept in aliquid ftate, fome freth leaves cf the cabbage, minced’
‘as has been dire&ted, may be infufed in a mixture of vitriolic
acid and water, of about the degree of acidity of vinegar; and
it may be neutralized, as it is wanted, either by means of chalk,
or
422. Mr. War's Method of preparing a Tel Liguor, &c.
or of the fixed or volatile alkali. But it 1s neceflary to. obfervé,,.
that if the liquor has an. excefs | of alkali, it will foon lofe its
colour, and become yellow, from’ which ‘late it cannot be
reftored; therefore care thould be taken to bring i it very saat :
to a blue, and_not to let it verge towards a green™. os ae
3. By the fame procefs I have made a red infufion of bis, :
which, on being neutralized, forms at prefent a very fenfible
teft;. but how long it will preferve its properties I have, not
yet determined. ‘Probably the coloured infufions of. other,
flowers may be preferved in the fame manner, by the antifeptic;
power of the vitriolic. acid, fo.as to lofe little of their original
fenfibility. Paper, frefh {tained with thefe tefts in their neutral
ftate, has fufficient fenfibility for many experiments; but the;
alum/and glue which enter into the preparation of writing-
paper feem in fome degree to fix the colour; and paper which
is not fized becomes fomewhat tranfparent, when wetted, »
which renders {mall changes of colour imperceptible; fo that
where accuracy is required, the teft fhould. be ufed-in a liquid
{tate +.
* Since writing the above, I have found, that the infufions of red cabbages ’
and of various flowers in water acidulated by means of vitriolic acid, are apt to
turn mouldy in the fummer feafon, and alfo that the moulding is prevented by the
addition.of fpirits of wine. The quantity of fpirit which is neceffary for this
purpofe I have not been able to afcertain; but 1 add it by little at a time, until
‘the progrefs of the moulding is prevented.
+ I have found, that the petals of the fearlet rofe, and hole of the pink-
coleured lychnis, treatedin this manner, afford very {enfible tefts. .
REA
Ge
ic Me
XXXI. An Account of a new Plant, of the Order of Fungi.
By Thomas Woodward, E/7; communicated by Sir Jofeph
Banks, Bart. P.. R. S..
Read June 10, 1784.
Plante nove Defcriptio— an Genus novum 2
Radices pauce ; tenues ; albidz.
Volva ovata; duplex, mucilagine interpofita; fubalbida..
Stipes, e volva interiore furgens, fublignofus; cavus ;
cortice lacerato veftitus ; fubfufcus.
Capitulum, ftipitis fummitati infidens, reflexum; fubtus
campanulatum, glabrum ; {uperne pulverulentum, et, e
pulveris: craffitie, globiforme ; ; volvze ruptee —
tem, minime adherentem, in fe gerens.
Pulvis fpharicus; femipellucidus; luteo-fufcus...
- ‘THIS extraordinary vegetable production arifes from a volva,
which is buried fix or eight inches deep in dry fandy banks 3
and, confequently, it is extremely difficult to dete& it in its
earlieft ftate. At its firft appearance above ground, the pow-
dery head’ is covered withta loofe campanulated ‘cap, which
does not adhere by any the {malleft filaments 5 and which, I
fuppofe, to be the upper part of the volva, as both always
appear ragged when taken up. When the plant is taken up:
immediately on its appearing above ground, the ftem is about
fy or eight inches long; and, as well as the volva, replete
with,
424 Mr. Wooswarn's Account of a
with mucilage, making it much heavier than when it has
attained its full growth. This is the ftate to which the de-
{cription given above refers. The duit is now perfeetly formed,
and is difperfed by the flighteft touch, or by the wind, A
great alteration foon takes place, as it now proceeds very rapidly, —
and in a few days attains the fummit of its growth, which is
from nine to fifteen inches, more than half being generally
buried in the ground, The ftem becomes woody, though
hollow, the bark ftill more ragged, and the whole plant much
lighter, both volva and {tem being now quite dry, and free
from mucilage. The wind and fhowers foon difperfe the
greateft part of the duft; and at length the ftalk appears with
a naked, coriaceous, campanulated pileus, and confiderably
bleached, in colour and appearance not unlike a dry ftalk of
hemp. In this ftate fome of them are now to be found (Aug,
28, 1783) with plants of this year rifing near them.
Mr. Humpureys, of Norwich, who firft found this very
extraordinary plant, met with it only in the ftate laft de-
{cribed, and without difcovering the volva; fo that no judge-
ment of it could be formed. It has been taken by fome per-
fons for a decayed or abortive agaric; but that opinion could
not be maintained by any one who had feen it in its recent
{tate.
I firft met with it in February or March 1783 in its dry
and withered ftate; but as it was fufpected, though with little
appearance of reafon, to be a decayed Agaricus procerus, I
wifhed to examine the root carefully, in order to obferve whe-
ther it was bulbous. The bulb of the Agaricus procerus is
{carcely hidden under the furface, and I was much {furprifed —
at the depth to which I was obliged to fearch for the root of
thisi
‘i
<.
new Plant, of the Order of Fungi. 425
this plant; at length, however, removing the earth carefully
to the depth of feven or eight inches, I met with it, and to
my great pleafure and furprife, on raifing the plant,’ I ditfco-
vered the volva, which was fo unlike the fugitive one of the
agaric, that I was immediately convinced it muft be fomething
new.
An account of this was dire@tly fent to Mr. Dickson, of
Covent-Garden, an able botanift, and diligent enquirer after
the clafs Cryptogamia. Mr. Dickson, who had before {een it
im the ftate in which it was found by Mr. Humpureys, but
could make nothing ofit, though thoroughly convinced it was no
agaric, immediately requefted that I would watch the fpot, and
endeavour to deteét the plant in its earlieft appearance. J com-
municated this to my neighbour Mr. Srone, a moft diligent and
fkilful botanift, who firft reftored the Lycoperdon coliforme; and
we determined to examine the fpot carefully together, from the
month of Auguft downward. About the middle of Auguft
we firft difcovered a plant juft arifen, which was fent to Mr.
Dickson, and a full defcription of which is before given; but
though we have daily vifited the fpot fince, we have never
been able to find it again in fo young a ftate; for fo rapid ap-
pears to be its growth, that we have found plants of two or
three inches height above the ground, the {tems of which had
loft part of their mucilage, where the day before none had been
vifible. We have three or four times attempted to difcover the
volva in its earlieft {tate, by removing the earth carefully near
the old ftems of the preceding year; but this has been without
fuccefs: and there is little hope of fucceeding in it, as the
volva lies very deep in the ground, and the plant arifes at fuch
various times.
VoL. LXXIV. ro Re This
426 Mr. Woopwann’s Account of a
This plant agrees with the genus Phailus in its volva, which
has a double coat replete with mucilage ; ; and its ftipes crowned _
with a reflexed pileus. But it more nearly approaches the —
genus Lycoperdon, by its head covered with a thick duft, con—_
tained in a fubflance of a fpongy appearance, and by the form
of the duft, which agrees perfectly with that of moft of the true:
lycoperdons, when examined in the microfcope. To this genus
it muft at prefent probably be referred, though the total want
of an exterior coat prevents its agreeing with it fo perfe@tly as. _
it ought.
The Mucor * fepticus of Hupson and Licurroot (Mucor
ovatus of ScH#FFER); the Mucor * butyraceus of SCHEFFER
(194.), not taken notice of by either Hupson or Licurroorm,,
but which I have often found here; and the Lycoperdon * epi-
dendrum of Licutroor, which I fuppofe to be what Hupsow
calls Lycoperdon epiphyilum, as he has referred to the fame
plate of Scua@rrer (193. Mucor fragiformis); have all fome
affinity with the frudtification of this plant; and the more fo,
if we {uppofe the head to be at firft covered with a mucilage,
which afterwards turns to a duft; but this will hardly be ad-
mitted, as the plant fent to Mr. Dickson had the duft per-
te&ly formed, though the volva and ftem were both. replete-
with mucilage. But we cannot admit it to agree with any of
thefe laft mentioned plants, as they have all an exterior coat,
though very fugitive, of which this feems entirely deftitute,
We may add, that they are all very fugitive productions ;
* T cannot help obferving that, in my opinion, Harier has done more rightly
20 making thefe into a new genus (Filago), than our botanifts, who have jumbled
them with the genera Lycoperdonand Mucor, to which they have no great affinity
any more than the Spheria of Hauzer, likewife very improperly ranked with the
Lycoperdons and Clavariz.
7 whereas
Philos Trans VolL XXIV, Vab XVI. ?-426.
4.26.
Philos Trans VolZL XXIV. Tab. XVI.
Aafire Se
new Plant, of the Order of Fungi. 427
whereas this, though foon arriving at maturity, is of a woody
and permanent firucture.
P.S, Ina letter Mr. Dickson received from Mr. Woop WARD,
Feb. 12, 1784, he informs him, that he is quite convinced by
fome late obfervations, that the above-mentioned plant fre-
quently comes to a {tate of perfection before it reaches the fur-
face. The only difference to be obferved is, that the duft in
that cafe is of a darker colour, which he fuppofes is owing to
its not being expofed to the air.
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XX. Experiments to inveftigate the Variation of Local Heat.
By James Six, E/y.; communicated by the Rev. Francis.
$Vollation, LiBp ho wos:
Read June ro, 1784.
EING defirous of inveftigating the variation of local
heat, I made the following experiments. Bd
_ On the 4th of September, 1783, I placed thermometers im:
three different ftations; one on the top of the high tower of
Canterbury Cathedral, about 220 feet from the ground; ano--
ther at the bottom of the fame tower, at about 110 feet;.
and a third in my own garden*, not more than fix feet from
the ground. They were all carefully expofed to the open air
in a fhady northern afpect ; the loweft was as little liable to be
affected by the refleGtion of the fun’s rays as the elevation
would permit, the fecond ftill lefs, and the higheft not at all.
They continued unremoved in their feveral places, where I
vifited them. daily for the {pace of three weeks, and minuted
down the greateft degree of heat and cold that. happened each
day and night in their refpective ftations +.
* This garden is fituate not far from the Cathedral, at. the extremity of the
buildings on the north fide of the city.
+ The thermometers here made ufe of were conftructed to fhew the greateft
degree of heat and cold which happened in the obferver’s abfence (defcribed Phil.
Trani, vol, LXXII. part J.), which rendered them particularly convenient on this
oceafion, They had hung together for fome time, and feldom differed half a
degree from each other.
By
Mr..Six’s Experiments to inveftigate, &c. 429
By thefe obfervations it appears, fee Table I. that, notwithftand-
ing fome irregularities, the heat of the days at the loweft ftation
always exceeded that at the middle, and ftil) more the heat at the.
upper ftation. As in many inftances the higher regions of the
atmofphere have been found to be colder than the lower, and’
the thermometer in the garden was more liable to be heated by
the reflection of the fun’s rays from the earth than the upper
ones, a difference of this kind might have been expected. But
Twas greatly furprifed to find the cold of the night at
the loweft, not only equal to, but, very frequently, ex-
ceeding the coid:at the higher ftations. As I wifhed to know,,.
whether thefe variations would continue the fame in the win--
ter, when the weather was colder; and: whether a thermo-.
meter, placed at fome diftance from the city, having an eleva--
tion equal to that on the top-of the Cathedral tower, would:
apree- with it; on the rg9th of December, 1783, I difpofed
the three thermometers in the following manner: one in my-
garden ; one on the top of the high tower, as before; and the
third on the top of St. Thomas’s Hill, about a mile diftant
from the city, where, at fifteen feet from the ground, it was
nearly level with that on the Cathedral tower.. ‘Table II. con-.
tains the obfervations that were then made*: ‘The weather
at this time proving cold, favoured the experiment ; and I now
found the feveral thermometers nearly agreeing with each other
in the day-time: but'in the night, the cold at the lower fta-
tion exceeded the cold at the higher ones rather more than it
did in the month. of. September, when the weather was:
warmer.
_* The few omiffions in this Table were occafioned by the feverity of the cold
preventing my attending at a proper time the thermometers, which were at a
confiderable diftance from each ather.
At
430 Mr. Six’s Experiments to inveftigate
At the time of taking thefe thermometrical obfervations, I
likewife noted the different difpofitions of the atmofphere in
other refpeéts: fuch as the preflure, moifture, and drynefs of
the air; force and direction of the winds; quantity of rain ;
whether the appearances of the fky were clear or cloudy, &e..
as I apprehended the local variation of the thermometers might,
in a certain degree, correfpond with fome particular change in:
the ftate of the atmofphere.
The event anfwered my expectation in a fingular manner
in refpect to the nocturnal variation ; for it generally happened,
that when the {ky was dark and cloudy, whatever was the con-
dition of the atmofphere with relation to the other particulars
above enumerated, the thermometers agreed pretty nearly with
each other; but, on the contrary, whenever the fky became
clear, the cold of the night at the loweft {tation im the garden
con{tantly exceeded the cold at the top of the Cathedral tower,
where the inftrument was placed 220 feet from the ground,
entirely expofed to the open air, wind,.dews, and rain, in
a fhady northern afpect.
The local variations in the day-time feemed to be regulated
by the general degree of heat only, without being affected by
any other particular difpofition of the atmofphere, or the clear-
nets or cCloudynefs of the fky, as the nocturnal variations were.
In the month of September, when the glafles rofe from 60° to
-a°, the heat at the lower ftation conftantly exceeded the heat
at the upper ftation; and in fome meafure proportionally, as
the weather was hotter *. In December and January. when
* Asthe heat at the lower ftation exceeded the heat at the upper ones, when
the weather was hot; and equally fo, whenever the fky was cloudy, as well as
when it was clear; it appears, that the glafs at the lower ftation was not mate-
rially affected by the reflection of the fun’s rays from the earth, as at firit F
apprehended % would be,
from
*
i
*
the Variation of Local Heat. — 43%
from below 30° they feldom rofe to 40°, the local variation im
the day-time nearly ceafed, or was found in very fmall degrees
inclining fometimes one way, fometimes the other.
That the clearnefs of the tky fhould contribute to the cool-
nefs of the air in the night, is not at all furprifing; but that,
whenever the {ky becomes clear, the cold fhould feem to arife from
the earth, and be found in the greateft degree, as long as itcon-
tinues clear, in the loweft fituation, feemsa little extraordinary :
this, however, appeared to be the cafe, both in the warmer as well »
as in the colder weather, during the whole time thefe obfervations
were taken, and remarkably fo on the following days. On the
firft of January the weatner was cold, the {ky cloudy, the glafies
in the night were at 20°, and in the day at 34°: the wind
which had been at S.E. the day before, changed in the evening
to S. and brought on a thaw. On the fecond of January
clouds and mifty rain darkened the fky all day; the wind
blew brifkly atS.W.; the glaffes in the night were at 32°%, in
the day at 40°. On the third of January the clouds and rain
continued, the weather growing ftill warmer; wind at S.W.
by S.; the glaffes in the night were at 36°, in the day at 45°.
‘Thefe three days. the weather gradually became warmer ; and,
while the fky remained darkened by clouds, all the glafles in
their feveral flations nearly agreed with each other. About
noon, on the third of January, the fky becoming clear, the
air grew cooler; and going into my garden, about eight o’clock
in the evening, I perceived the furface of the ground, which
had been wet by the rain in the forenoon, began to be frozen.
Looking immediately at the thermometer, I faw the mercury at
33°23 and obferving a piece of wet linen hanging near the
——
a
glafs, not five feet from the ground, I took it into my hand,
and found it not in the leaft frozen; by which it appeared,
that
432 Mr. S1x’s Experintents to invefigate
that the degree of cold which had frozen the ‘furface of the
ground, had not then afcended to the glafs, nor to the linen, —
and confequently had not been communicated to the air five or
fix feet above the earth. The next day I found, as I expected,
a confiderable local variation; the index for the cold of the
night in the garden being at 32°, that on the hill bemg
at 35°3, and that on the top of the tower at 37°3 *.
Probably the weather -did not continue clear the whole
night; if it had, it is likely the:degrees of cold would have
been found proportionally greater at every ftation. On the
morning of the 4th there fella mifty rain, which continued
only till noon, when the fky became clear again, and con-
tinued fo tillthe 7th; during which time the nocturnal heights
of the Pe i ik differed confiderably from each other ;
but on the fky’s becoming cloudy, the local variation ceafed.
Thermometrical obfervations, made under the fame cir=
cumftances in refpect to the feafon of the year, place, and
fituation +, may probably be liable to fimilar local varia-
* Tt is remarkable, that the thermometer on St. Thomas’s hill did not vary
fo much from that in the garden, as that did which was on the Cathedral tower,
although thefe two elevated glaffes were within three feet of a perfect level with
each other; the variations, however, as often as they happened, inclined the
fame way. ‘The reafon of this might probably be, that although the glafs on the
hill was at an equal altitude with that on the tower, in refpect to the ground on
which the Cathedral ftands: yet the former was only 15 feet, while the latter
was 220 feet from the ground.
+ Situation in regard to hillor valley. The valley m which Canterbury ftands
is at that place about a mile in breadth, opening tothe N.E.; the hills‘on either’
fide do not rife very fudden, nor very high; the river Stour, divided into branches, ”
paffes through the city, and, about fourteen miles below, empties itfelf into the ~
fea, which wafhes the coaft from the NN.W. round by the E, to the S.; diftant ©
from the city at different places ‘from fix to fixteen miles,
Ao 2 tions —
the Variation of Local Heat. 433
tions : to thofe who make them, the refult of thefe experiments
may be of fome ufe. If convenient opportunity offered, I
fhould be glad, by the affiftance of friends, to try the local
difference of heat and cold in more diftant, as well as more
elevated, fituations.
By experiments of this kind it may poffibly in fome mea-
fure be found, how far evaporations from the earth, at certain
times, or vapours afcending, deicending, or meeting, in dif
ferent parts of the atmofphere, may increafe or diminifh the _
heat of the air in thofe places: or whether different degrees
of heat and cold (fubje&t however to change) may not be found
in different ftrata of air, or vapour, floating in different parts
of the atmofphere; or in what degree and proportion, the cold
increafes at different altitudes and in different feafons of the
year: whether the cold, which is known to be very intenfe in
the fummer time on the tops of high mountains, receives a
proportional increafe, or be not lefs fubject to variety by the
return of winter and fummer, night and day, than what we
experience in the plains below.
March 10, 1784. JAMES SIX.
Vox. LXXIV. Lil TABLE
"
Aix
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Tia. Bo ay i
The greateft daily variation of heat and cold in the atmofphere, from the 4th to the 24th of September,
1783, taken from three different ftations, and compared together. One thermometer placed on a
towér in Canterbury, 220 fect from the ground; another at the bottom of the fame tower, 110; and a
third in a garden, about fix feet from the ground. _N. B. The no&turnal degrees of cold belong to the
night immediately preceding the day to the date of which they are placed.
Greateft degree of cold in the night.
Greateit degree of heat in the day,
Se 5 < eon d
A Gi) oe colsk a 855~ ony — fen — 4B
io : : z a aa «foe
be a a yrs) Gt Ws 54 oon
S 26 v See QS) (208 ape | og 2|y 8
a osula 3 Ele os joselay {2 8e2)/8q
5 £5 = 9S o|c BS jee ole Boéfe8
2 ES Lie $1 SHS Ba Be: 5.5 Siow
5 o = geese eo joe zlaon, Jen “12
2.5 6/€ Fy oteal 5 aS Sleoe|5 q oa
E Biase 25 o|& Bo (ESBS Sle doe g
FA ols p=: = 4 al ey
2 =|} Az 5a 2° till ike lea 4
& ae) & 2 & ta fea] & EES.
© ° ° 9 ° ° ° 6 Morning ftill and foggy; wind began to blow,
505 7 = 5r — | -9o§ 66 61 61 +5 in the forehdon at S.W.; clouds and fain
in the afternoon and night; 3 bar. 29.3.
Morning cloudy ; heavy” rain; aileeies in the}
afternoon ; j wind high at W.N.W.; bar!
29.3,
62% | 613 | 615 | 41
| { Morning rained a little; wind very high *
S.W. moft part of the day; bar. 20.5.
ry
day; wind very high at W.; bar. 29.8.
Sometimes clear, fometimes cloudy; wind
very 1s at W.; bar. 29.9.
Morning Be and cloudy; clear at noon;
Seise|[e eed || ALIS Wa ee wind brifk at S.W.3 bar. 29.5.
Morning and great part of the day élear;
wind high at S.W.; evening clear; bar,
632 | 62t| 63 41 +08 ons clears continued fo moft part of the
{ 29.6,
Morning clear; cloudy about noon; bri
BS ,
635 62 Coys lar 23 | wind atS.; evening flill, bar. 29.8. ;
Morning cloudy; wind high at S.; evening}
z Bs )
69 a; 65 He +# Hill and clear; bar. 20.45 ;
Morning clear; a little rain at noon; cloudy]
65 62 62 +3 +3 afternoon; wind brifk at S,; bar. 29.0.
Morning cloudy ; moiftwarm air; wind brifk
68% | 663 | 64] +2 | +4 at S.W.; mifty rain; cloudy evening; bar.
29.8.
2 L Morning cloudy; wind moderate S.W.; in
70 68 66 IE | ht tthe evening changed to N.; bar, 29.5. :
Morning hazy; thin clouds all day; little
3 x g hazy; 3 3
65 623 | 61 +3 | +4 Wind at N.E.; clofeand warm; bar, 29.8,
Dull and hazy moft part of the day; little
pe Bg a
62s | Gr Goh | +13 | +2 breeze of wind at N.E.; bar. 30.1. q
e , 1 | { Very dullallday ; wind brifk at N.E.3 bar
625 | 62 6x | +O] +12 |. 29.9.
J Morning clear; a little rain in the afternoon;
I 3
72.) O73, | OF FRE WS I< windlsisie, : baty2g (6: |
f Cloudy ail day, with rain and wind S.W.;
L clear at night; bar. 20.4.
a
as
uy)
fy
w
iy
=
RN
ae
Sy
nin
448 47k 48% | =3 P| 63% (iy 60k | +23 | +3 eee wind at S.W.,; clear moft part
of the day; wintl S.; bar, 29. &
t Rain moft part of the day; evening hazy ;|
59 58 58 att +1 { wind S.W.; bar, 29.6. : ai
Morning Ti and mifty; a little fiower in
63 593 593 | +33 | +33 the afte thoon, clear all the reft of the day ;
F wind 8.W.; bar. 29.6.
63 593 | 583 | 4-34 | +44 | Clear all day; wind W. andN.W,; bar. 29.8.
Vou. LXXIYV. Lila FABLE
TABLE Il.
The greateft daily variation of heat and cold in the atmofphere from the 2oth of December, 1783, to the
8th of January, 1784, taken from three different ftations, and compared togethers One thermometer
placed on a tower in Canterbury, 220 feet from the ground; another on a hill, a mile diftant, but on
the fame level with that on the tower; athird in agarden, about fix feet from the ground. N.B. The
nocturnal degrees of cold belong to the night immediately preceding the day to the date of which
they are placed.
Greateft degree of cold in the night
Greateft degree ot heat in thie day.
repo ee Te regency L be
EE es BS jes jes ¢ é 28 5
Sy [9 2 |) 2 Sea S ca?
Ex |= | E2 |ss4lgs 8 E ou 2
S| 25 282 /2s las & bear
Ase] oe) eee jae joe a Ab
"Dec. = 5 éi ie 5 > Evening preceding clear; morning clear;
20] 20 25 252 | —5 - 53 395 —of | wind brifk at W.; cloudy at noon ; air very|
; moitt; barometer at 29.9.
Morning clear on the hill; fog in the city;
21] 292 gos | 32 =—1 —2} 373 38 38 —o3 | - o} little wind at N.W.; air moift: cloudy at
U noon ; alittlefnow ; bar. 29.8.
(Morning flight fog in the city; little wind
22|. 22 244 | 25% | —2i | —33 34 34¢ | 36 —0}| —2 at N.W.; air moift; cloudy at noon; ai
‘ little fhow; bar. 29.7.
5 ary a 3 I Fes leer x | f Dark and cloudy allday; wind brifk at S.W. 5
23) 313 | 34 | 32 o8 39% | 40% | 372 92 || $24 { air moift; evening foggy; bar. 29.8. |
a4 a3 1 3 1 |J Morfing rainy; clear at noou; cloudy late in
24, 312 | 33 342 | -15 25 43a | 42 41g | T14 | +22 the evening; wind at N.; bar. 29.6.
- Morning cloudy; wet mift; wind brifk atE.,
25| 26 27 = aaigetd| Peco 36 355 | — +o; | — towards evening rain mixed with fnow;
E; nighf clear; bar. 29.2,
Morniig foggy, a little fhow about noon;
26} 262 265} 28 —— | —1F 33% 34 36 —0o} | —25 evenifg clear in the zenith; little wind at
N.; bar. 28.9.
E Morning clear; cloudy at noon; little fnow
27| 25 264] 28 | —13 | —3 36 342 | 352 | +14 | —o% { in the evening; moderate breeze of windat
N.E.3; bar. 29.3.
2 z al x | _51 | { Morning dark andcloudy; wind very brifc at
28] 30 29 203 | +1 +07 334 | 30 332 | +Ts 5 11 NEL; air dry, and felt very cold; bar. 29.3.
Morning hezy; dry mifty air; wind very
3 5 ay a 3 y
29) 21 21k | o2 | —ok } —3 24% | 245 Os { cold and brifk at S.E. by E.; bar, 29.7-
Morning clear in the zenith; dry mifty fo
30) 153 15 163 +o | -1 22 ait 21F | +03 | +0} below; wind yery cold and brifk at S.E.
U bar. 29.7.
(Sometimes clear, fometimes cloudy; wind
3i} 123 113 13 +of | —o2 arr} — 21% | —— | — [4 britk at S.E.; evening Tain with {now ;
wind S, very high in the night; bar. 29.4.
Jan. Wet mift all day; wind mod
n , a iy; Wind moderate at W.;
1| 20 _— 20 | ——| — 34 =m 332 | ss | 102 { bar, 29.44 4
j Morning thick fog and mifly rains wind S.E.;
2| 324 32 32t | tof | —— 40 393 40 +o | —— |4 afternoon and evening very high at S.W.
° C with rain; bar. 29.6.
Morning rainy; wind S.W. by W.; clear at
6 acl 6 +0 —— 453 45 453 | +of } —— { noon$ afternoon and eveniny very clear and
Ad 8 Nad 3 Ws 4 fill; wind S.W.; bar. 29.6.
Morning mifty rain;. wind high at S.; even-
4| 32 354 | 37% | —33 | —5% 465 | 443 | 453 | +13 | +1 { ing very clear and fill; bar. 29.8. :
Morning very clear; little wind at N.E. even-
5}. 263 293 3I =3 45 363 352 | — +1 { ing veryclear and ftill; bar. 30.1.
Morning very clear; moderate breeze o
6) 213 | 26 27%} —4i | —6 31 303 | — | +03 | —— { ae at SE.; evening very clear and ftill;
ar. 30.26
; ¢ Morning yery clear; cloudy about noon ;
7) 16 19 205 | -3 —4t 29 27k agi | +13 | +13 evening dark and cloudy; little wind at
| S.E,; bar. 50.0.
Morning dark and clofe; very dark all day;
8} 26 255 | 252 | +03 | +o} 32 32 BIE | == | Ok { wind W.N.W.;, bar. 29.8. :
The greateft daily variation of heat and cold in the atmofphere from the 20th of December, 1783, to the
. Sth of January, 1784, taken from three different ftations, and compared together. One thermometer
placed on a tower in Canterbury, 220 feet from the ground ; ; another on a hill, a mile diftant, but on
the fame level with that on the tower; athird in agarden, about fix feet from the ground. N.B. The
nocturnal degrees of cold belong to the night immediately preceding the day to the date of which
they are placed.
Greateft degree of cold in the night Greateft degree of heat in the day.
e caeats 4 a= S : ; ¢
oer OL: ou |o 8 og oS 2: egies [se
2 oO wees] as a mors — oO aes =o |Co & =
o wo Qi since ozs (Osinerss Dike eee) oc pea tek ben) * . ® oth Oo moe
(Ses elie Bo fut -}au & Ba =e Bo fut Oo &
of | ¢ BY Gee Sc | Oc 2 Sion} & g [eos =i Sie >
Ey fel a 2 oe |h oe lo © 5 By & So |% @sl/8 6 &
pia S mre a8) Go) 3S Oe Koa u wo vo 4 ke ig = Eas
Det ey melee edo 15S eee aé§ ie ee asec
He |B H § IA» oA ee y= nS ja» IQ &
4 Dec s - 4 é = a 3 6 a A Evening preceding clear; morning clear;
201 20 25 252 == 5 = Sz 305 37% 39% +14 —OF wind brifk at W.3 cloudy at noon; airvery
moift; barometer at 29.9.
: ( Morning elear on the hill; fog in the city ;
21|- 202 Boe ale 20 —1 —25 EE: 385 38 —OF | - Of | little wind at N.W.; air moift: cloudy at
L noon; alittlefnow ; bar. 29.8.
( Morning flight fog in the city; little wind
22/98 24d | 252 | —2h | — 35 34 342 | 36 —O2 | —2 at N.W.; air moift; cloudy at noon; a
| little fnow; bar. 29.7.
k and cloudy allday; wind brifk at S.W
5 3s oe eieaes | ~ aetyt es ot ite ee ax | Datkan ? ee
a ta (a we 394 | 404 | 3/2 ae i | air moift; evening foggy; bar, 29.8.
A pees ous 2 x 3 1 |f Morning rainy; clear at noou; cloudy late in
2A alg | 832" | 2 34k | SIR} 24 432 [42 | 43g] tla | +22
the evening; wind at N.; bar. 29.6.
=e - < 2
fi, 437...
XXXII. Account of fome Obfervations tending to invefligate the
Confiruction of the Heavens. By William Herfchel, H/q.
TONS
Read June 17, 1784,
Na former paper I mentioned, that a more powerful in-
(trument was preparing for continuing my reviews of the
heavens. The telefcope I have lately completed, though far
inferior in fize to the one I had undertaken to conftruét when
that paper was written, is of the Newtonian form, the object
{peculum being of 20 feet. focal length, and its aperture 18.7,
inches. The apparatus on which it is mounted is contrived fo
as at prefent to confine the inftrument to a meridional fi ituation,
and by its motions to give the right-afcenfion and declination
of a celeftial objet in a coarfe way ; which, however, is fuf-
ficiently accurate to point out the place of the object, fo that it
may be found again. It will not be neceffary to enter into a
more particular def{cription of the apparatus, fince the account
I have now the honour of communicating to the Royal Society
regards rather the performance of the telefcope than its con-
ftruction.
It would, perhaps, have been more eligible to have waited
longer, in order to complete the difcoveries that feem to lie
within the reach of this inftrument, and are already, in fome
refpects, pointed out to me by it. By taking more time I
ould undoubtedly be enabled to fpeak more confidently of the
EV 2 > interior
438 Mr. Herscuer’s Obferustions on
interior confitruétion of the heavens, and its various mebulaus and
fidereal frata (to borrow a term from the natural hiftorian) of
which this paper can as yet only give a few outlines, or rather »
hints. Asan apology, however, for this prematurity, it may
be faid, that the end of all difcoveries being communication,
we can never be too ready in giving facts and obfervations,
whatever we may be in reafoning upon them.
Hitherto the fidereal heavens have, not inadequately for the
purpofe defigned, been repretented by the concave furface of a
{phere, in the center of which the eye of an obferver might
be {uppofed to be placed. It is true, the various magnitudes
of the fixed ftars even then plainly fuggefted to us, and would
have better fuited the idea of an expanded firmament of three
dimenfions ; but the obfervations upon which Iam now gomg
to enter ftill farther illuftrate and enforce the neceflity of con-
fidering the heavens in this point of view. [fn future, there-
fore, we fhall look upon thofe regions into which we may
now penetrate by means of fuch large telefcopes, as a natu-
ralift regards a rich extent of ground or chain of mountains,
containing {trata varioufly inclined and direéted, as well as
confifting of very different matetials. A furface of-a globe or
map, therefore, will but ill delineate the interior parts of the
heavens.
It may well be expected, that the great advantage of alarge
aperture would be moft fenfibly perceived with all thofe objeéts
that require much light, fuch as the very fmall and immenfely
diftant fixed ftars, the very faint nebula, the clofeand com-
prefled clufters of ftars, and the remote planets. |
On applying the telefcope to a part of the v/a /actea, I found’
that it completely refolved the whole whitifh appearance into
{mall ftars, which my former telefcopes had not light enough
3 to
the Conftruction of the Heavens. 439
to effect. The portion of this extenfive traét, which it has
hitherto been convenient for me to obferve, ts that immediately
about the hand and club of Orion, The glorious multitude
of ftars of all poffible fizes that prefented themfelves here to
my view was truly aftonifhing ; but, as the dazzling brightnefs
ef glittering {tars may eafily miflead us fo far as to eftimate their’
number greater than it really is, I endeavoured to afcertain’ this’
point by counting many fields, and computing, from a mean
of them, what a certain given portion of the milky way
might contain. Among many trials of this fort I found, laft
January the 18th, that fix fields, promifcuoufly taken, con-
tained 110, 60, 70, go, 70, and 74 ftars each. 1 then tried
to pick out the moft vacant place that was to be found in that
neighbourhood, and counted 63 ftars. A mean of the firft
fix gives 79 ftars for each field. Hence, by allowing 15 mi
nutes of a great circle for the diameter of my field of view, we
gather, that a belt of 15 degrees long and two broad, or the
quantity which [ have often feen pafs through the field of my
telefcope in one hour’s time, could not well contain lefs thar
fifty thoufand ftars, that were large enough to be diftin@ly
numbered. But, befides thefe, I fufpected at leaft twice as:
many more, which, for want of light, I could only fee now
and then by faint glittering and interrupted glimpfes.
The excellent colleétion of nebula and clufters of ftars
which has lately been given in the ConnoiJance des Temps for
1783 and 1784, leads me next to a fubjeét which, indeed,
muft open a new view of the heavens. As foon as the firft of
thefe volumes came to my hands, I applied my former 20-feet
reflector of 12 inches aperture to them; and faw, with the:
greateft pleafure, that moft of the nebula, which I had an
opportunity of examining in proper fituations, yielded to the
Lils force
440 Mr. HerscuEr's Objervations on |
force of my light and power, and were refolved into ftars.
For inflance, the 2d, 5,.9, 10,12, 13, 14, 15, 16, 1Q, 225 24,
9841394 914375 $%> $2153; 55x56, 625/65, 66; 67) aia
74,92, all which are faid to be nebula without ftars, have
either plainly appeared to be nothing but ftars, or at leaft to:
contain ftars, and to fhew every other indication of confifting
of them entirely. 1 have examined them with a careful {eru-
tiny of various powers and light, and generally in the meri- _
dian. I fhould mention, that five of the above, viz. the 16th,
24, 375 52, 67, are called clufters of ftars containing nebulo-
fity; but my inftrument refolving alfo that portion of them
which is called nebulous into ftars of a much {maller fize, I
have placed them into the above number. To thefe may be
added the +ft, 3d, 27,33, 57, 79, 81, 82, 191, which in my
7, 10, and 20-feet reflectors fhewed a mottled kind of nebulo-
fity, which I fhall call refolvable; fo that I expect my prefent
telefcope will, perhaps, render the ftars vifible of which |
fuppofe them to be compofed. Here I might point out many
precautions neceflary to be taken with the very beft inftruments,
in order to fucceed in the refolution of the moft difficult of.
them}; but referving this at prefent too extenfive fubje&t for a
future opportunity, I proceed to {peak of the effects of my latt
inftrument with regard to nebule.
My prefent purituits, as I obferved chai requiring this
telefcope to act as a fixed inftrument, I found it not convenient
to apply it to any other of the nebula in the Connodfance des —
Temps but {uch as came in turn ; nor, indeed, was it neceflary 5
to take any particular pains to look for them, it being utterly:
impoflible that any one of them fhould efcape my obfervation _
when it paffed the field of view of my telefcope. The few which,
I have already had.an opportunity of examining, fhew plainly that
a thofe
the Conftruétion of the Heavens. At
thofe moft excellent French aftronomers, Meff. Mrssrer and Mz-
CHAIN, faw only the more luminous part of their nebulx ;
the feeble fhape of the remainder, for want of light, efcaping
their notice. ‘The difference will appear when we compare
my obfervation of the g8th nebula with that in the Connoiffance
des Temps for 1784, which runs thus: ‘* Nebuleufe fans étoile,
<¢ d’une lumiere extremement foible, au defius de Vaile boréale
66 de la Vierge, fur le parallcle et pres' de: Vetorle N°'6)/‘cin=
“<quicme grandeur, de la chevelure de Beérénice, fuivant
Pecamsterp.. M. Mrcwain Ja vit le 15° Mars, 1584"
My obfervation of the 30th of December, 1783, is thus: A
large, extended, fine nebula. Its fituation fhews it to be M.
MEssier’s 98th; but from the defcription it appears, that that
gentleman has not feen the whole of it, for its feeble branches
extend above a quarter of a degree, of which no notice is taken.
Near the middle of it are a few ftars vifible, and more fufpected
My field of view will not quite take in the whole nebula. See
fig. 1. tab. XVII. Again, N° 53. “* Nébuleufe fans étoiles,
op decouverte au-deflous et prés de la chevelure de Bérénice, 4
< peu de diftance de l’étoile quarante-deuxieme de cette conftel-
“6 lation, fuivant Framstrep. Cette nébulenfe eft ronde et
“© apparente, &c.” My obfervation of the r7oth Sweep runs’
thus: A clufter of very ¢lofe ftars; one of aie moft beautiful »
objedts I . remember to have feen in the heavens. The clufter
appears “under the form of a folid ball, confifting of fmall ftars,
quite comprefied into one blaze of light, with a great number
of loofe’ ones furrounding i it, and Ses vifible in the getre-:
ral mats. “See fig. iy hae ou fi
en ‘Tegan my ‘prefent feries of Bier illtotie I furmifed,
that feveral nebulae’ might yet remain undifcovered, for want’
of Sufficient light'to dete& them’; and'was, tlidref¥ie, in Hepes
of
mes Mr. Herscuer’s Obfervations on
of making a valuable addition to the clufters of ftars and ne=_
bulze already collected and given us in the work before referred
to, which .amount.to 103. ‘The: eve nt has plainly. proved
that my expectations were well founded : for I have already
found 466 new nebule and clufters of {tars,.none of which,
to my prefent knowledge, have been feen before by any perfon 3
moit of them, indeed, are not within the reach of the belt |
cominon telefcopes now in ufe. In all probability many more
are ftill in referve; and as I am purfuing this track, I fhall_
make them up into feparate catalogues, of about two or three.
hundred at a time, and have the honour of prefenting them i i.
that form to the Royal Society.
A very remarkable circumftance attending the nebulz and
clufters of ftars is, that they are arranged into ftrata, which
feem to runon to a great length ; and fome of them I have
already been able to purfue, fo as to guefs pretty well at their
form and direction. It is probable enough, that they may fur-
round the whole apparent fphere of the heavens, not unlike
the milky way, which undoubtedly is nothing but a ftratum of
fixed ftars. And as this latter immenfe ftarry bed is not of —
equal breadth or luftre in every part, nor runs on in one ftraight
direction, but is curved and even divided into two ftreams
along a very confiderable portion of it ; we may likewife expect
the greateft variety in the ftrata of the clufters of ftars and ne-
bulz. One of thefe nebulous beds is fo rich, that, in paffing
through a fection of it, in the time of only 36 minutes, T-
detected no lefs than 31 nebula, all diftin@ly vifible upon a— |
fine blue fky. Their fituation and fhape, as well as condition, —
feems to denote the greateft variety imaginable. In another
ftratum, or perhaps a different branch of the former, I have .
feen double and treble nebulz, varioufly arranged; large ones”
with
the Confirudtion of the Heavens, 4.4%
with fmall, feeming attendants; narrow but much extended,
fucid nebule or bright dafhes; fome of the fhape of a fan, re-
fembling an electric brufh, iffuing from a lucid point; other
of the cometic fhape, with a fen ming nucleus in the center;
bg
n
or like cloudy flars, furrounded with a nebulous atmofphere; a
different fort again contain a nebulofity of the milky kind, like
that wonderful, inexplicable phenomenon about @ Orionis ;
while others fhine with a fainter, mottled kind of light, which
denotes their being refolvable into ftars. See fig. 3. &c. But ir
would be too extenfive at prefent to enter more minutely into
fuch circumftances, therefore I proceed me the fubje of ne-
bulous and fidereal ftrata.
ft is very probable, that the great ftratum, called the milky
way, is that in which the fun is placed, though perhaps not in
the very center of its thicknefs. We gather this from the
appearance of the Galaxy, which feems to encompafs the whole
heavens, as it certainly muft do if the fun is within the fame.
For, {uppofe a number of ftars arranged between two parallel
planes, indefinitely extended every way, but at a given confi-
derable diftance from each other; and, calling’this a fidereal
ftratum, an eye placed fomewhere within it will fee all the
ftars in the direftion of the planes of the ftratum projected
into a great circle, which will‘appear lucid on account of the
accumulation of the ftars; while the reft of the heavens, at
the fides, will only fee to be fcattered over with conftella-
tioils, more or lefs crowded, according to the diftance of the
planes or number of ftars contained in the thicknefs or fides of
the ftratum. | |
Thns, in fig. 16. (tab. XVIII.) an eye at S within the ftratum
2b, will fee the ftars in the direction of its length 24, or height
ed, with all thofe in the intermediate fituations, projected into the
VoL. LXXIV. Mmm lucid
\
444 Mr. Herscuer’s Ober vations on
lucid circle ACBD; while thofe in the fides m v, nw, will be
feen fcattered over the remaining part of the heavens at
MVNW. |
If the eye were placed ieee without the ftratum, at
no very great diftance, the appearance of the ftars within it.
would aflume the form of one of the lefs circles of the {phere,,
which would be more or lefs contracted to the diftance of the
eye; and if this,diftance were exceedingly increafed, the whole.
ftratum might at laft be drawn together into a lucid {pot of any.
fhape, according to the pofition, length, and height - of the.
ftratum.
Let us now fuppofe, that a branch, or fmaller ftratum,,
fhould run out from the former, in a certain direction, and. let.
it alfo be contained between two parallel planes extended inde--
finitely onwards, but fo that the eye may be placed in the great
ftratum fomewhere before the feparation, and not far from the.
place where the ftrata are fill united. Then will this fecond:
{tratum not be projected into a bright circle like the former, but:
will be feen as a lucid branch proceeding from the firft, and.
returning to it again at a certain diftance lefs than a femi-circle..
Thus, in the fame figure, the ftars in the fmall ftratum pg,
will be projected into a bright arch at PRRP, which, after its.
{eparation from the circle CBD, unites with it again at P.
What has been inftanced in parallel planes may eafily be ap-:
plied to {trata irregularly bounded, and running in various direc.
tions; for their projections will of confequence vary. according.
to the quantities of the variations in the ftrata and the diftance
of the eye from the fame. And thus any kind of curvatures,
as well as various different. degrees of brightnefs,, may be pro-
duced in the projections. |
2 From
the Conftruciion of ihe Heavens. AAS
_ ‘From appearances then, as I obferved’before, we may infer,
that the fun is moft likely placed in one of the great ftrata of
the fixed ftars, and very probably not far from the place where
fome fmaller ftratum branches out from it. Such a fuppofition
will fatisfactorily, and with great fimplicity, account for all
the phenomena of the milky way, which, according to this
hypothefis, is no other than the appearance of the projection of
the ftars contained in this ftratum and its fecondary branch.
As a farther inducement to look on the Galaxy in this point of
view, let it be confidered, that we can no longer doubt of its
whitifh appearance arifing from the mixed luftre of the num-
berlefs ftars that compofe it. Now, fhould we imagine it to
be an irregular ring of ftars, in the center nearly of which we
muft then fuppofe the fun to be placed, it will appear not a
little extraordinary, that the fun, being a fixed ftar like thofe
which compofe this imagined ring, fhould juft be in the center
of fuch a multitude of celeftial bodies, without any apparent
reafon for this fingular diftinétion ; whereas, on our fuppofi-
tion, every ftar in this ftratum, not very near the termination
of its length or height, will be fo placed as alfo to have its
own Galaxy, with only fuch variations in the form and luftre
of it, as may arife from the particular fituation of each ftar.
Various methods may be purfued to come to a full know-
ledge of the fun’s place in the fidereal ftratum, of which I
fhall only mention one as the moft general and moft proper for
determining this important point, and which I have already
begun to put in practice. I call it Gaging the Heavens, or the
Star-Gage. It confifts in repeatedly taking the number of ffars
in ten fields of view of my refletor very near each other, and
by adding their fums, and cutting off one decimal on the right,
a mean of the contents of the heavens, in all the parts which
Mom m 2 are
446 Mr. HERsScHEL’s Od/ervations on
re thus gaged, is obtained. By way of example, I have jomed a q
fhort table, extracted from the gages contained in my journal,
by which it apyraies that the number. of {tans Wikies vary
faft as we approach the Via Ladtea. WF oi
————
> o)
e
cs
4
inv)
fav]
Ug
NAAR
ol
é
et ty
os NS O OO 5
"Thus, in. the. parallel from a to, 4. degrees, north
polar-diftance, and. R.A. 15h. 10’, the ftar-gage runs, yp
from g-4 ftars in the ficld to 18.6 in about.am hour and a:-half 3
whereas in the parallel from 76°.to 80° north. polar diftance,,
aud R. A. 11, 12, 13, and, 14 hours, it very feldom:
rifes above 4. We are, however, to remember, that with
different inftruments the account of the gages will be very
' different, efpecially on. our fuppofition of the fituation of | the
fun ina ftratum of ftars. For, let a 4, fig. 17, be.the ftratum, and
fuppotfe the fmall circle g 47h to reprefent the fpace into which,
by the light and power of a given telefcope, we may pene
trate; and let GHLK be the extent of another portion, which
we are enabled to vifit by means of a larger aperture and power 5
it is evident, that the gages with. the latter inftrument will
differ very much in their account of ftars contained at MN,
and at KG or LH; when with the former they will. hardly, be
atfeéted by the change from mz tog or/4. And this accounts
for what a celebrated author fays concerning the effects of t
le
the Conftruction of the Heavens. 447
fcopes, by which we muft underftand the beft of thofe that
are in common ufe *.
It would not be fafe.to.enter into an application of thefe, and
fuch other gages as I have already taken, till they are fuffi-
ciently continued and carried all over the heavens. I hall,
therefore, content myfelf with, juft mentioning that the fitua-
tien of the fun, wall. be obtained, from confidering im what
manner the flar-gage agrees, with the iength of a ray revolving
‘nm feveral direCtions, about an aflumed. point, and cut off by the
i of the rata Thus,, i 28 1§,-let,S be the Pass ¢ of
Bee tin! the ene to one of fe re ae! ae re=
prefented by the plane AB. ‘Then, fince. neither the fituation.
ef S, nor the form: of the limiting furface AB, is given,. we
are to-aflume a point, and apply to it lines. proportional: to. the
feveral. gages. that have been obtained,, and, a , fach. angles.
from each: other as they, may: point out ; them will the. termi-
nation of thefe lines delineate the boundary, of the: ftratum,.
and confequently manifeft the fituation of: ae fun. within the
fame.. But to proceed... ..,.
_If the fun fhoeuld: be placed i in the oreat ‘fdbreal Rote of
the milky way,, and, as we have furmifed above, not far from:
1 : : :
* Onvoit avec les télefcopes des étoiles dans toutes les parties du ciel, 4 peu
prés comme dans la voie lactée, ou dans les nébuleufes.- On ne fauroit douter
qu'une partie de V’clat et dé la blancheur de la voie laétée, ne provienne de la
Tnmitre des: petites étoiles qui-s’y trouvent en effet.par millions; cependant, -avec
les plus grands télef{copes,, on n’en diftingue pas affés, et elles n’y font pas affée:
rapprochées les unes des autres pour. qu’on puiffe attribuer 4 celles qu’on diftingue
Ya blancheur de la.voie laétée, fi fenfible A la vue fimple. L’on ne fauroit donc
prononcer que les étoiles foient la feule'caufe de cette blancheur,. quoique nous: ne
connoiffions aucune: maniére fatisfaifante de lexpliquer. Aft, M. Deua-Lanne,
S 833;
the
448 Mr. HERscue1’s Od/ervations on
the’ branching out of a fecondary ftratum, it will very natu
rally lead us to guefs at the caufe of the probable motion of
the folar fyftem: for the very bright, great node of the Via
Latis, or union ‘of the two {trata about Cepheus and Caf iopeia,
and the Scorpion and Sagittarius, points out a conflux of ftars
manifettly quite fufficient to occafion a tendency towards that
node in any ftar fituated at no very great diftance; and ‘the
fecondary branch of the Galaxy not being much lefs than a
f{emi-circle feems to indicate fuch a fituation of -our folar fyftem
in the great undivided ftratum as the-moft probable.
What has been faid in a former paper on the fubjeCt of the
folar motion feems alfo to fupport ‘this fuppofed fituation’ of
the fun’; for the apex’there affigned lies nearly in the dire€tion
of a motion of the fun towards the node'of the ftrata. Be-
fides, the joining ftratum making a pretty large angle at the
junction with the primary one, it may eafily be admitted, that
the motion of a ftar in the great ftratum, efpecially if fituated
confiderably towards the fide fartheft from the fmall ftratum,
will be turned fufficiently out of the ftraight direétion of the
great ftratum towards the fecondary one. But I find myfelf
infenfibly led to fay more on this fubject than I am as yet au-
thorifed to do; I will, therefore, return to thofe obfervations
which have fuggefted the idea of celeftial f{trata.
In my late obfervations on nebule I foon found, that I ges
nerally detected them in-certain directions rather than in others;
that the {paces preceding them were generally quite deprived of
their ftars, fo as often to afford many fields without a fingle
itar in it. that the nebule generally appeared fome time after
among. ftars of a certain .confiderable fize, and but feldom
among very {mall ftars; that when I.came to one nebula, I
generally found feveral more inthe neighbourhood; that after-
wards
the Conftruétion of the Heavens. 449
wards a confiderable time pafled before I came to another par-
cel; and thefe events. being often repeated in different altitudes
of my inftrument, and fome of them at a confiderable diftance
from each other, it occurred to me, that the intermediate
fpaces between the {weeps might alfo contain nebula;. and
finding this to hold good more than’ once, I ventured to give
notice to my afhiftant at the clock, ‘* to prepare, fince I ex-
‘¢ peéted in a few minutes to come at a ftratum of the nebula,,
“« finding myfelf already” (as I then figuratively. exprefled it).
<¢ on nebulous ground.” In this I fucceeded immediately ; fo.
that I now can venture to point out feveral. not: far diftane
places, where I fhall foon carry. my telefcope, in expectation of
meeting with many. nebulz. But how far thefe circumftances.
of vacant places preceding and following the nebulous ftrata,
and their being as it were contained in.a.bed of ftars,. {paringly
fcattered between them, may hold good in more diftant por-
tions of the heavens, and which, L have not: yet been. able to
vifit in any regular manner, I.ought by no means to hazard a.
conjecture.. The. fubject is new, and we mutt attend to obfer-
vations, and be guided by them, before we form general:
opinions. ;
Before I conclude, I may, however, venture to add a few:
particulars about the direction of fome of the capital ftrata or.
their branches: The well known nebula.of. Cancer,.vifible to.
the naked eye,.is probably. one belonging to a-certain {tratum,.
in which I fuppofe.it.to be fo placed as to lie neareft.to us. This-
ftratum I fhall call that of Cancer. It runs from:. Cancri:
towards the fouth over the 67 nebula. of the Connoiffance des:
Temps, which is a very. beautiful.and pretty much compreffed.
elufter of ftars, eafily to be feen by any. good telefcope, and in:
which Ihave obferved above 200. ftars at. ence in the field of:
view:
430 Mr. Hersewers Obfervations me:
view of my great reflector, with a power of 1 WE This cluffer
appearing fo plainly with any good, commen telefcop: Ne.
being fo near to the one which may be feen by the naked eye,
denotes it to be probably the next in diftance to that within the
quartile formed by y, 2, 4, 8; from the 67th nebula the ftratum
of Cancer proceeds towards the head of Hy dta ; but I have not
yet had time to trace it farther than the equator.
Another ftratum, which perhaps approaches nearer to the
folar fyftem than any of the reft, and whofe fituation is nearly
at retangles to’the great fidereal ftratum in which the fon is
placed, is that of Coma Berenices, as 1 fhall call it. I {uppofe
the Coma itfelf to be one of the clufters init, and that, on ac-
count of its nearnefs, it appears to be fo fcattered. It has
many capital nebule very near it; and in all probability this
ftratum runs on a very confiderable way. It may, perhaps,
even make the circuit of the heavens, though very likely not
in one or the great circles of the fphere: for, unlefs it thould
chance to interfect the great fidereal ftratum of the milky way
before-mentioned, in the very place in which the fun is fla-
tioned, fuch an appearance could hardly be produced. . How-
ever, if the ftratum of Coma Berenices fhould extend fo far as
(by takimg in the affiftance of M. Mrssrer’s and M. MecHain’s
excellent obfervations of fcattered nebulae, and fome detached
former obfervations of my own) I apprehend it may, the di-
redtion of it towards the north lies probably, with fome wind-
ings, through the great Bear onwards to Cafliopeia ; thence
through the girdle of Andromeda and the northern Fith, ‘pro-
ceeding towards Cetus; while towards the fouth it pafles
through the Virgin, probably on to the tail of Hydra andthe
head of Centaurus. But, notwithftanding I have already fully
afcertained the exiftence and direétion of this ftra, um for more
3 than —
Ee Sing,
Ly hy
Waly
| Wy?
Lith Mirans Nil Le ANNA Tab. XVILZ. 400.
——— =|
7
- te ee Se ee eee ye SF
—"
Philos Trans. Vol L XXIV. Vab XVIUL yp. 470.
* > a ok ok
¥ ai UR Se
ey EE ok
ea ssc tw Me nfau chistes em
oe nu
IIL p.4 50.
X\
XU Tab
(LL
Niles Trans
L
* 4 #
*
4c ——
e ae ek & Aa ee
* eK Pees TB AE AK se. She * * ay
oe se Se
the Confiruttion of the Heavens. ASE
than 30 degrees of a great circle, and found tt almoft every
where equally rich in fine nebula, it till might be dangerous
to proceed in more extenfive conjectures, that have as yet no
more than a precarious foundation. I fhall therefore wait till the
obfervations in which I am at prefent engaged fhall furnifh me
with proper materials for the difquifition of fo new a fubject.
And though my fingle endeavours fhould not fucceed in a
work that feems to require the joint effort of every aftronomer,
yet fo much we may venture to hope, that, by applying our-
felves with all our powers to the improvement of telefcopes,
which I look upon as yet in their infant ftate, and turning
them with affiduity to the ftudy of the heavens, we fhall in
time obtain fome faint knowledge of, and perhaps be able
partly to delineate, the Interior Confiruction of the Univer fee
Datchet near Windfor,
April, 1784. ‘WILLIAM HERSCHEL,
Vox. LXXIV, Nna
Bi agaeu
‘ ugh
bO-O-408 An Account of a new Species of the Bark-Tree, found
in the Ifland of St. Lucia. By Mr. George Davidfon 5 COMm=
municated by Donald Monro, M. D. Phyfician to the Army,
1 OA ASS : |
Read June 24, 1784.
DR. DONALD MON R Ge
s1X;
AVING received from my correfpondent Mr. Davin+
son, furgeon, in the ifland of St. Lucia, fome Bark,,
the product of that ifland, which is faid to poflefs the virtues:
ef the Jefuit’s Bark, and in a much fmaller dofe, I thall
efteem it a favour if you will lay before the Royal Society the |
f{pecimen which I have fent to you with this letter, together
with Mr. Davipson’s account of it, if you think they me=
rit that honour.
I have examined the dried fpecimens very carefully. They
are not fo well preferved as I could with; but I have fince feen
much finer in the pofleffion of Sir JosepH Banks, who has:
done me the honour to fayour me with the following charaéter,.
as moft diftinétive of it from the other fpecies of Cinchona:
already defcribed, which he gave me an opportunity of. ©
examining,
Ie 9
Mr. Davipson’s Account, &c. 453
It is undoubtedly a Cinchona, but not the Cinchona offici-
nalis of Linnus; for it differs from it effentially in its bark
in feveral particulars. It has an emetic quality not common to
the true bark, breaks more woody and fplintery, and is far
more naufeous to the tafte. Its decoction is of a dull Bur-
gundy colour; and its extract refembles more the bitter of
Gentian than that of the Quinguina. I have procured four
ounces of it from half a pound of the Bark boiled in water,
and herewith fend to you a {mall {pecimen.
The drawings, which accompany this letter, are exact co-
pies of the fpecimens which I received; I therefore hope they
will not be thought unworthy the acceptance of the Royal
‘Society. .
I have the honour to be, &c.
Hienrietta-fireet, Nov. 6, 1783. G. WILSON.
Botanic character of the Bark-Tree of St» Lucia.
“* Cinchona floribus paniculatis, glabris; laciniis linearibus,
*¢ tube longioribus; ftaminibus exfertis3 foliis ellipticis, glabris.”
Extract of a Letter from Mr. Georce Davivson, dated St.
Lucia, July 15,°1733.
IT is now about four years {ince Mr. ALEXANDER
ANDERsoN difcovered in the woods, near the Grand Cul de
Sac, fome trees refembling, in the botanical characters, the
Nnn2 true
Pane Mr. Davinson’s Account of
‘true Quinguina of Linnzus. He brought the bark, flowers,
and feeds, to Dr. Youne of the General Hofpital, and trial
was made of it there; but not being fufficiently dried, its ftrong
emetic and purgative qualities prevented its exhibition.
The publication of Dr. SaunpERs, which I received about
two months ago, mentioning the introdu@ion of a {fpecies of
bark of a redder colour, and poffefling greater powers than
the bark formerly in ufe, induced us here to try the bark of
this country. Dr. Youne had by him fome that was col-
le&ted in General GranT’s time: on account of the length of
time it had been kept, and its being fufficiently dried, he has
met with all the fuccefs he could with.
It is manifeftly more aftringent than the bark, and the bitter
is likewife more durable on the palate.
Hitherto I have generally ufed the cold infafion, either in
lime or fim’ple water, in the proportion of one ounce to three
pints of the water. I have likewife given it in fubftance from
twenty to thirty grains; but never exceeded the laft quantity,
for I never found the ftomach able to retain more than twenty
grains. ,
Joined with the Canella alba, it forms in fpirits an agreeable
and elegant tinéture. I have made a tincture from the feeds,
which are infinitely ftronger in tafte than the bark itfelf.
(Signed) GEO. DAVIDSON.
Mr.
a new Species of ibe Bask Free | 455
Mr. George Davidfon’s account of the Bark-Tree of the ifland
oe of St. Lucia.
THE Bark-Tree of this ifland is nearly about the fize of the
cherry-tree, feldom thicker than the thigh, and_ tolerably
firaight; the wood is fight and porous, without any of the
bitternefs and aftringency of the bark itfelf.
* Tt delights in a fhady fituation, the north-weft afpe& -of
hills, under larger trees; and 1s generally to be found about
the middle of an hill, near fome running water.
The leaves are large, oblong, oppofite, and plain, preferving
(as well as the flowers and feeds) the bitter tafte of the bark.
In the beginning of the rainy feafon (June), the tree puts
forth its flowers in {mall tufts; at firft they are white, but
afterwards turn purplifh. The fltamina are five in number,
with a fingle ftyle. The germen is oblong, bilocular, and
- furrowed on each fide. The feeds are many, and of the winged
kind. The corolla is monopetalous, with its mouth divided
into five long fegments.
The foil in general where it grows 1s a ftiff red clay. The
bark itfelf is of a lighter red than that fent out here to the
hofpital under the name of red bark. It inclines more to the
colour of cinnamon. The bitternefs and aftringency appear to
be greater than in either of the other barks.
I apprehend, the proper feafon for obtaining it is about the
month of March, before the flowers come cut: after-expe-
rience will beft determine this.
Infufed in cold water, in which form, or in lime-water, I
generally ufe it, it forms a very red tincture, pofiefling the
3 | bitternefs
456 Mr. Davinson’s Account of, &e.
bitternefs and aftringency of the bark very ftrongly. A few
drops of the Tinétura florum martialium give it a very. black
colour, and occafion a copious depofition of a black fediment.
Te does the fame with the fpirituous tinéture.
With {pirits it forms a beautiful red tincture.
Explanation of the references tab. XIX.
A. A branch of the Cinchona of St Lucia, with the flowers
not yet opened. |
B. The entire feed-vefiels.
C. A feed-veflel fplit.
D. One of the feeds, of its natural fize.
HE. The fame magnified.
ess
LhitosLrans Vol. L XXIV. Tab. X1Xp. 456.
Liles Trans Vol LXXIV, Tab XIX p.456-
Bafiored
“
i
“te
Se el ee
i ee ae
[ 457. ]
EXXV. An Account of an Obfervation of the Meteor of Avgutt
18, 1783, made on Hewit Common aear York. In a Letter
from Nathaniel Pigott, E/g. F. R. S. to the Reverend Nevil.
Matkelyne, D. D. F..R. S. and Afironomer Royal.
Read June 24, 178 4s.
' REVEREND SIR, York, Od. r8, 1783:
N the roth of laft Auguft 1 communicated to you an ac»
count of the remarkably fine meteor, which I had feen
under circumftances peculiarly favourable the preceding night,
I was then preparing myfelf for a journey into the Eaft Riding ;.
and, on that account, obliged to poftpone the verifications,.
mentioned hereafter, till my return,
On the 18th of Augufl, about ten o’clock P.M. after a hot
day, the weather a little hazy, but not fo as to obliterate the
flars, and no wind, being on horfeback, in company with two |
other gentlemen, on Hewit Common, about three miles from.
York,my attention was attracted towards the W.N.W. by feveral.
faint flathes of lightning, fuch as.are often feen near the horizon,.
er which may be {till better compared to flafhes of an aurora:
borealis.. Soon after which I perceived fome luminous matter
in motion, and collecting together from feveral directions, fig.
t. (tab. XX.) which immediately taking fire prefented itfelf under
the form of a ball, of fo vivid. a brightnefs, that the whole
horizon was: illuminated, fo that the fmalleft obje& might
z have:
"are
458. - Mr. Pieorr’s Account of
have been feen on the ground. This ball, when formed, be-
gan to move, with an eafy fliding motion, from W.N.W. —
towards the S.S.E.. It fuggefted the idea of a highly brilliant |
comet, emitting a train or tail, but of a different colour from.
the ball itfelf, this laft being of a moft brilliant bluifh white,
and the tail of a dufky red, the length of which appeared to
extend over fifteen or more degrees of the heavens, fig. 2.
The apparent diameter of the nucleus feemed one-third or one-
fourth of the full moon’s diameter. The greateft difficulty in
this eftimation hence arifes, that I cannot, notwithftanding all
my endeavours, reprefent in my mind the moon otherwife
than as a plane or difk; nor the meteor, than as a {pherical. body.
The altitude of it, when it formed in the W.N.W. was about
30°; and about 19° or 20° above the horizon, when it became
extinct in the S.S.E. a few fparks of the tail, neareft the
nucleus, {cattering themfelves much in the fame manner as
thofe of a fky-rocket when burnt out, fig. 3.
It has been faid, that the ball divided itfelf into three or
four parts before its extin€tion. ‘To me it appeared to vanifh
or gently die away: what confirms mein the opinion, that it did
uot divide, is, that the three or four {cattering parts above-men-
tioned were not of the bright colour of the ball itfelf, but of
the dufky red which the tail invariably fhewed. ‘The interval
of time from the meteor’s formation to its extin@tion was
nearly twenty feconds, perhaps two or three feconds lefs. The
long habit I have of counting feconds in aftronomical ob-
{ervations induces me to think this quantity may be relied on 5
and this I mention, becaufe fome have eftimated it more, fome
lefs. Nine or ten minutes after its diffipation, I heard a noife,
much refembling the report of a cannon at a very great dif-
tance; but I would not with to have it underftood, that I
{peak
a
the Meteor of Auguit 18, 1783. 4<9
{peak to this Jaf interval with the fame certainty as to the
other; if, however, it be exact, and fuppofing found to move
1106 feet in one fecond of time, and the fame in the upper
regions of the atmofphere as here below, which, however,
may be very different, its diftance from me, at its extinction,
mutt have been about 120 miles, and its perpendicular altitude
above the earth’s furface about 40 miles.
I have added a fcheme and a {mall fketch, prefuming by
that means to convey a clearer idea of what I faw. The alti-
tudes, azimuths, &c. are not merely from eftimation. After
my return from the Eaft Riding, I went to the very {pot, where
I had feen the meteor on the 18th of Augutt. The road, as
in the fcheme, being exa@ly ftraight from my ftation, both
towards and from York, no mittake can arife in that refpec.
With all the circumftances clearly and forcibly imprefled on
my mind, I watched till fome remarkable {pot in the {ky pre-
fented itfelf at the fame place in which I had feen the meteor
itfelf form, crofs the road, vanith, &c.: then, with a theo-
dolite, I took the feveral bearings, which may be the more
relied on, as I repeated the operations three different times, on
different fpots, which agree furprifingly well for meafures
where no minute exaétnefs can be expected, I have marked
minutes in the fcheme, becaufe the refults gave them, without
any pretenfion to fuch nicety.
Iam, &c.
NATH. PIGOTT.
Vou. LXXIV. Ooo
f 460 ]
age
XEXVI. Odfervations of the Comet of 1783. In a Letter from —
Edward Pigott, E/g. to the Rev. Nevil Mofeliae D. D..
F.R.S. and Affronomer Royal.
Read. June 24, 1784. |
REVEREND SiR, York,. Dec 1 yas.
AVING compleated my obfervations of the comet I
difcovered on the tgth of November lait, I take the
liberty of defirmg you to prefent them to the Royak Society.
The faintnefs of the comet’s light, and the unfavourable fky
you have had in the fouth, induce me to- believe, that few
obfervations of it have becn. made befides the following.
~ T Apparent | North de-{Greateit error P ;
| ps a gees clination. jof each R. A. Longyude,|Lariads
(ae —_——- _-— anne”
| 17 1783 h. / ° / / ° / / / ut S ce] / ° ,
Novem. 19 BE 4 Ld gh Qi ky 4 3; 09 1 9.37 112 429
10 $55—|40 ©: 3) 4 32 4) © 22 | 1 >. 2Biiavee
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26) 10 g—!34 49 20] 12 3 3 OES 1 6 33712 6
\Decem.. 2 gl 15.54 [29°21 Sol 20 15 3 © 40 | 1 4 24) 975422 N
The R. A’s of November 2oth, 24th, and 26th, were de-
duced from obfervations made at the tranfit inftrument: the
others, except the firft, were determined with an excellent 22
feet night-glafs, made by DoLzonp, magnifying zo times,
having crofs wires at right angles in its focus, which were.
3 vifible
Phitos Dans Vol L XXIV. Tab. XX. p. 460.
‘quam.
Phitos Trans Vol LXXIV Tab XX. p. 460.
= 7 - Rifere Ns
Mr. Picorr’s Obfervations of the Comet of 1733. 464
vifible without being illuminated. With this inftrument the
comet, by the common method, was compared to ftars in the.
field of the telefcope, and within four minutes on the fame
parallel. ‘The places of thofe flars were afterwards fettled
with the meridian inftruments. As fometimes feveral ftars
were obferved, I eafily found to what degree of certainty thofe
obiervations might be depended on, which I have marked with
the above refults. ‘The declinations, I think, cannot err two
minutes, being compared to {tars within four minutes on the
fame parallel. The three of November 20th, 24th, and 26th,
were taken with the tranfit inftrument by comparing the comet
to the neareft ftars. I was much chagrined in not being able
to fee the comet in our equatorial when the wires were illu-
minated.
The comet had exactly the appearance of a nebula:
its light was fo faint that it could not be feen in a
good opera glafs. In the night-telefcope the nucleus was
{carcely vifible, and the diameter of the furrounding coma
was about three minutes of a degree. Between the roth and
26th of November, I thought it had rather diminifhed in
brightnefs. December the 1ft and 3d it was very difficult to
be feen, occafioned perhaps by its little elevation above the
horizon. Between December the 3d and roth, the comet was
entirely effaced by the increafed light of the Moon. On the
roth, the moon being in the horizon did not obliterate ftars of
the eighth or ninth magnitude; but I could not And the comet.
The following obfervations were made by my friend Mr. Joun
(GOODRICKE.
Oo002 Dates
462 Mr. Picort’s Obfervations of the Comet of 1783.
North decli- |.
j pa \
Dates. J 4
time nation,
ye } Senin eceeennene - a rr |
i 38. ee? iain ail inh S guar ay
UR af} 3} s ; | .
Novem.24 | 8 16 | 26" ab &y ORBOs i wo aie I 4238
FeB- by Onn BLA 220990, Oo] aa mos Tr 5,552.19 525M
ED W),PLGO Vt
P. S. This morning I received a letters from: M. ps:
Mecuain, in which he informs me, that he difcovered the
comet on the 26th of November feven days after my firft ob-
fervation. He has made feveral obfervations on it. )
XXXVII. Experiments on mixing Gold with Tin. In a Letter
from Mr. Stanefby Alchorne, of bis Majefty’s Mint, to Peter
Woulte, Hyg. F. R. 8.
Read June 24, 1784.
| Seed eae eee
OU know it 1s a generally received opinion among me-
tallurgifts,. that tin has a property of deftroying the duc-
tility of gold, on being melted with it, even in very fmall
quantities. Our late ingenious countryman Dr. Lewis, in his
Philofophical Commerce of Arts, p. 85. has. well expreffed
the fenfe of moft writers on this. fubjeét, in the following
words: ‘* The moft minute proportion of tin and lead,” fays.
he, ‘“‘ and even the vapours which rife fromthem im the fire,
<¢ though not fufficient to.add to the gold any weight fenfible
‘< in the tendereft balance, make it fo brittle that it flies in.
«6 pieces under the hammer.”
Divers circumftances, neverthelefs, long fince induced me
to difbelieve the fa&t; but thefe, having chiefly arifen from
{mall experiments, did not feem to warrant any general con-
clufion. A late public occafion, however, which led me to.
various trials of mixing thefe metals together, in different pro-
portions, and in. ie eee large quantities, has put the matter
out of difpute;, and fhewn me, that tin, in {mall quantity at
leaft, may be added to gold, either pure or alloyed, without
producing any other effeét than what might eafily be con-
ceived,
464 Mr, ALcuorne’s Experiments a
ceived, @ priori, from the different texture of the two metala | 4
In confirmation of which, I beg leave to lay fome of the ex- _
periments before you.
EXPERIMENT 1.
Sixty Troy grains of pure tin were ftirredinto twelve ounces
of refined gold, in fufion; and the mixture was then caft into
a mould of fand, producing a flat bar, one inch wide, and one-
eighth of an inch thick. The bar appeared found and good,
fuffered flatting under the hammer, drawing {everal times be-
tween a large pair of fteel rollers, and cutting into circular
pieces, of near an inch diameter, which bore ftamping in the
money-prefs, by the ufual ftroke, without fhewing the leaft
fign of brittlenefs; or rather with much the fame dudtility as
pure gold.
© Slee Bei ME. Nee eb.
Ninety grains of like tin were added to twelve ounces of
fine gold, ftirred, and caft as above. The bar produced was
{carcely diftinguifhable from the former, and bore all the ope--
rations, as before-mentioned, quite as well
EXPERIMENT iii.
One hundred and twenty grains of fine tin were mixed with
twelve ounces of fine gold, and being caft like the foregoing,
produced a bar rather paler and harder than the preceding,
but which fuffered the like operations very well; except that,
on drawing between rollers, the outer edges were difpofed to
crack a little,
E X P E-~
: on mixing Gold with Tin. 465
BE xP Eon DM BE Noe. TY.
‘One hundred and forty grains, or half an ounce, of the
like grained tin, were mixed, as before, with twelve ounces
of fine gold; and the bar refulting from this mixture was
completely found and good; evidently paler and harder, how-
ever, than any of the foregoing, and cracking rather more
than the laft on pafling between the rollers; but bearing every
other operation, even {tamping under the prefs, by the common _
force, without any apparent injury.
EXPERIMENT ¥.
One ounce of tin was next ftirred into twelve ounces of the
like refined gold, and then caft as before; but the bar pro-
duced, though feemimgly folid and good, was bad coloured,
brittle in texture, and, on the firft pafling between the rollers,
fplit into feveral pieces, fo that no. farther trials were made
with it.
EXP eR REM EN OVE.
To inquire how far the fumes of tin, brought into: contact
with the gold, would do more than mixing the metal in fub-
ftance, a {mall crucible, filled with twelve ounces of ftandard
gold, 4! fine, was placed in a larger crucible, having one
ounce of melted tin in it, and kept there in fufion, the whole
being covered by another large inverted crucible, for about
half an hour. In this time a full quarter part of the tin was.
calcined ; but the gold remained unaltered, and equally capable
of being manufactured as another portion of the fame gold.
melted in the common manner.
a Mr. ALCHORNE’S Experiments 4
It may well be afked, whether the tin, or part of it, in
every trial, might not be deflroyed, and thus render the con-
clufions fallacious? But as, in any of thefe experiments, not
more than fix or eight grains of the original weight were mif-
fing after the cafting, and as even fine gold can fearcely be
melted without fome lofs in the operation, fo we may rea-
fonably fuppofe; that our {mall loties, in the foregoing trials,
do not deferve confideration.
The above experiments then feem to thew, that tin is not fo
mifchievous to gold as hath been generally reprefented. But
it would be unfair to infer, that the original author of this
_ doétrine (from whom fo many have implicitly tranfcribed) had
no foundation for the affertion. Gold and Tin, indeed, are
{ubftances pretty well known ; but it is eafy to imagine, that
coins or trinkets may have been ufed for one, and impure tin,
or pewter, perhaps, for the other; and it is difficult to guefs
what might be the refult of fuch uncertain combinations. To
inquire farther, therefore, the experiments were continued as
follows.
7
‘
:
A
f
:
EXPERIMENT VII.
To determine whether the two metals might be more inti-
mately combined, and the mafs rendered brittle, by additional
heat; the mixture of gold and tin, produced in the firft of
thefe experiments, was re-melted in a f{tronger fire than before,
and thus kept in fufion full half an hour. By this operation
fix grains only were loft in the weight; and the bar obtained
was no lefs manufacturable than at firft.
on mixing Gaia with Tin. 4.6 ;
EXPERIMENTS VIII. AND IX.
The mixtures of gold and tin, from the fecond and fourth
experiments, were re-melted feparately, and one ounce of
copper added to each. Being both well flirred, they were caft
as ufual; and the bars, though fenfibly harder, bore all the
operations of manufacturing as before. The laft bar cracked
a little at the edges, on drawing through the rollers, as it had
done without the copper, but not materially, and bore cutting
rather better than in its former ftate.
EXPERIMENTS X. AND XI.
A quarter of an ounce of the laft mixture (being tin half
an ounce, and copper one ounce, with gold twelve ounces),
and as much of the bar from experiment the third (being tin
one hundred and twenty grains with gold twelve ounces), were
each melted by a Jeweller, in the moft ordinary manner, with
acommon fea-coal fire, intofmall buttons, without any lofs of
weight. Thefe buttons were forged by him into {mall bars,
nealing them often by the flame of a lamp, and afterwards |
drawn each about twenty times through the apertures of a
ftee] plate, into fine wire, with as much eafe as coarfe gold
commonly paffes the like operation.
EXPERIMENT XII.
To enquire whether the adding of tin to gold, aay
alloyed, would caufe any difference, fixty grains of tin were
ftirred into twelve ounces of ftandard Bold, 22) fines and tle
refult pafled every operation before defcribed, without fhewing
the leaft alteration from the tin.
For greater certainty, feveral other trials were made, of dif-
ferent mixtures of copper, tin, and filver, with gold, even fo
Vo. LXXIY. Ppp low
¢
408 Mr, Avcuorne’s Experiments, &c.
low as two ounces and a half of copper, with half anounceof _
tin, to twelve ounces of gold, But thefe are not. worth par- .
ticularizingg for they all bore hammering, and flatting by
rollers, to the thinnefs of {tiff paper, and afterwards working
into watch-cafes, cane-heads, &c. with great eafe. They all,
indeed, grew more hard and harth, in proportion to the quan-
tity of alloy; but not one of them had the appearance of
what all workmen well know by the name of brittle gold.
Whence it fhould feem, that neither tin in fubftance, or the
fumes of it, tend much to render gold unmanufacturable.
Whenever, therefore, brittlenefs has followed the adding:
{mall quantities of tin to fine gold, it muft be fuppofed to have
arifen from fome unfriendly mixture in the tin, probably from
Arfenic; for other experiments have fhewn me, that twelve
grains of regulus of arfenic, injected into as many ounces of
fine gold, will render it totally unmalleable. |
From the foregoing experiments, I prefume, we may fairly
conclude, that though tin, like other inferior metals, will
contaminate gold, in proportion to the quantity mixed with it,
yet there does not appear any thing in it {pecifically inimical to
this precious metal. And this being contrary to the doétrine
of moft chemical writers, I fubmit to your better judgement,
whether it may not be ufeful to publifh thefe experiments, by
laying them before the Royal Society.
* Bam, es
Ss. ALCHORNE
“ey
_ 469. s |
XXXVIII. Sur un moyen de donner as Direltion aux Machines
Mi Aéroftatiques. Par M, Le Cotte De Galvez. Communicated
by Sir Jofeph Banks, Bart. P. Tee be)
‘ Read July ae es
OUS fouffignés certifions, que M. le Comte pe Gatvez
“nous ayant communiqué fes idées fur le moyen de pou-
-voir donner la direction aux machines a€roftatiques, pour faire
route a volonté et par un rumb certain et affuré dans lair, prin-
cipalement fondé fur différentes obfervations qu’il avoit faites
fur ufage que les oifeaux: font de leurs ailes quand ils volent,
et fur celui que font les poiffons de leurs nageoires et de leur
queue quand ils nagent :
Nous nous fommes -tranfportés, l’apres-midi da prémier
Mars de cette année 1784, au canal de Manzanarés, of on
avoit preparée une chaloupe de vingt-cing pieds’ de long fur
quatre et demi de large, avec une machine qu'il avoit inventée
pour demontrer fes idées. Cette machine *, qui confiftoit en un
‘chevalet gui alloit de poupe 4 proue a la hauteur de cing pieds,
étoit croifée en rectangles par trois vergues de bois élaftique,
de dix-huits pieds de long chacune, avec une alle a chaque
Bout, compofée de baguettes de baleine, couvertes d’un mor-
ceau de taffetas de cing pieds de long, et trois de large, laquelle
€toit jointe par un de fes quatre cotés a la vergue, de fagon que
Paile reftoit horifontale. Le mouvement fe communiquoit a
chaque vergue, et par confequent a fes-deux alles, par un feul
homme, qui tirant avec vitefle des cordes attachées aux bouts
de chaque vergue, les agitoit verticalement, d’ou refultoit que
* See tab, XXI. fig. 1.
Ppp2 | | quand
470: Le Comte pe GaLvez fur un Moyer, &c. ’
quand elles fe plioient, les ailes prenoient a leurs extrémités
une inclination de quarante-cing degrés de Vhorifon, Ce
mouvement et celui de la réa€tion produifoient dans la chaloupe,
ou il y avoit fix hommes, une impulfion qui la faifoit marcher
contre le courant du canal et le peu d’air qu’il faifoit, cent cin-
quante pieds par minute, outre foixante pieds qu’elle parcou-
‘rott avant de s’arréter depuis: Vinftant qu’on ceffoit de mouvoir
les atles: elle parcouroit deux cents quarante-trais pieds. pas
minute, allant avec le courant et lair, par le méme mouvement
continu des alles. : 2
Nous fimes. tous trés-etonnés de Teffet que produifit cette
expcilence; car, quoique le defir qu’avoit Pinventeur de mettre
fes idées en pratique au plutét, fut caufe qu'il fe fervit dune
chaloupe lourde et mal conftruite, avec laquelle les ailes.
n’avoient pomt ce proportion; nous fommes perfuadés que.
la fituation des ailes et leur mouvement vertical, qui formoient
lors qu’on les battoieat un plan incliné, imitant en cela les.
oifeaux et les poiffons, fourniflent un principe fir et certain
pour donner une direétion par quelque rumb que fe foit, 4 toute
efpéce de corps qui magent dans un fluide, et par conféquent
trés-applieable aux nouvelles machines aéroftatiques.
Cette invention nous paroit digne de Vapprobation et de
eloge des phyticiens qui, fans doute, employeront leurs efforts
pour lui donner toute la perfection dont elle eft fufceptible dans
Vexécution de fon mécanifme.
Et pour conftater que la dite expérience a, été faite de Ia ma-
nicre qu’on vient d’expofer, nous avons figné la prefente certi-
fication, ainfi qu’un deffein de la dite machine, a Madrid le
deux Mars, mil fept cent quatre-vingt-quatre. D. JosEF DE
Viexa, D. Acustin Betancourt ¥ Mortina, D. Ricarpo
Worsiey, Raim ve S. Laurent, CAsIMirE ORTEGA.
[47 J
XXXIX. An extraordinary Cafe of a Drop/y of the Ovarium,
with fome Remarks. By Mr. Philip Meadows Martineau,.
Surgeon to the Norfolk and Norwich Hojpital; communicated
éy John Hunter, Bf. F. RK. S.
Read July 5, 1784.
ne ae KIPPUS, a pauper in the city of Norwich, was,
7 for many years, a patient of my father’s, and, at his de-
ceafe, was under the care of Mr. Scor, as city furgeon, who:
obliged me many times by taking me to the poor woman, from:
whom I received the account of the early part of her difeafe.
Her complaints came on firft after a mifcarriage at the age of
27. She had never been pregnant before; and her difcharges
at that time were fo great as to bring her into a very weak
condition. She foon perceived fome uneafinefs, attended with a
fwelling, on one fide, which, after a few months, became too:
large to diftinguifh whether it was greater on one fide or the
other. As the {welling was found to arife from water,
it was drawn off, which wasin the year 1757. She was never:
afterwards pregnant; but the catamenia continued regularly
till the ufual period of their ceffation. When I firft faw her,.
which was in the year 1780, fhe had been many times tapped,. -
and fhe was then full of water. Her appearance was truly
deplorable, not to fay fhocking. She was rather a low woe
man, and her body fo large as almoft wholly to:obfcure her
face, as well as every other part of her: with all fhe was tole-
3 rably
472 Mr. MarTInEAau’s Account of ae
rably chearful, and feldom regarded the operation. 1 faw her 4
juft before we took away 106 pints of water, and I begged 4
leave to take a meafure of her. She was fixty-feven inches and
a half in circumference, and ftom the cartilago enfiformis to
the os pubis thirty-four inches. Her legs were now greatly
{welled; but this, and every other fymptom of which the
complained, evidently arofe from the quantity and weight of
water. She neither ate nor drank much, and made but a {mall
quantity of urine.
The operation of drawing off the water was generally per-
formed on a Sunday, as the moft convenient day for her neigh-
bours to affift her; and before the latter end of the week the
was able to walk very well. She was firft tapped in the year
1757, and died in Auguft 1783. Thus fhe lived full twenty-five
years with fome intervals of eafe, having eighty times under-
gone the operation, and in all had taken from her 6631 pints
of water, or upwards of thirteen hogfheads.
I will fubjoin the account of the dates, and the quantity
drawn off at each time, as given me by Mr. Sco, obferving
that till 1769 no exact memorandum was kept, except of the
number of times, although the quantity of water drawn off
was always meafured. By my father fhe was tapped twenty-
fix times, averaged at 70 pints each time: by Mr. Donne once,
73 pints, which makes 1683 pints from fome part of the ir
1757 to-1769. By Mr. Scorr as follows : |
1769.
1769.
Mar. 16.
July 17.
Nov. 20.
Bec: gt.
1770.
April 15.
Aug. 11.
Dec. 4-
Te
Mar. 22.
July 14.
Nov. 3.
1772.
Feb. 22.
June 6.
Sept. 12.
Dec. 12.
1773+
March 7.
May 29.
Aug. 29.
Dec. 5»;
\
an extraordinary Cafe of Drepjy.
Pints.
70
72
78
70
~.-geg
1774.
Mar. 13.
June 26.
Od. 23.
1775°
Jam. 24.
May 28,
Sept. 13.
Dec. 16.
1776.
April g.
July 28.
Nov. 276
1777.
. Mar. 16.
July.27.
Nov. 9.
1778.
March 8.
July 5.
_ Nov. 5.
Pints.
77
89
9 7,
258
P™7T79-
Feb. 28.
June 13.
Aug. 17.
O&. 24.
1 Dec. 10.
| 1780.
Feb..6. —
Papi. 22.
July 24.
Sept. 10.
Noy. 12.
178i.
Jan. I.
Mar. tle
| June 25.
OG. 14.
$ 17826
Jan..13-
Mar. 18.
June 2.
) Aug. 25.
Nov. 170
473
Pints.
"306 +;
108
92
99
go
495
1s Saas ae
ye
" aos | Mr. Mantingav's Account of
“783. Pints.
Feb. 14. 104
May it. 100 ..
July 20. 98
Aug. 11 onopening 78
380
Total 6631 pints.
In looking over this account it appears, that 108 pints was
the greateft quantity ever taken away at any one time; that —
fhe was never tapped more than five times in any one year ;
and the largeft quantity in a year was 495 pints. The moft
colleéted in the fhorteft {pace of time was 95 pints in feven
weeks, from July 24th to September roth in 1780, which is
very nearly two pints a day. It appears alfo, that in the laft
a4 years of her life, when a regular account was kept, fhe
increafed fafter in the winter than in the fummer months,
If the fix fummer months from April to September inclufive
are reckoned, fhe loft in the 14 years in 23 operations 1972
pints, and in the winter months from O&tober to March inclu-
five, by 30 tappings, 2596 pints; and it will be found, that 30
is to 2596 rather more than 23 to 1972, fo that feven more
tappings were at leaft neceflary in the winter than in the fum-
mer. In the months of March and November fhe oftener un-
derwent the operation than in any other. In thefe calculations
the three months in 1783 are not included, as the year was not
finifhed. |
If we compare the famous cafe of Lady Paces, related by — |
Dr. Mean, the quantity of water taken from her ladyfhip —
appears {mall when oppofed to the number of pints drawn
| from
an extraordinary Cafe of Dropfy. Avs
from Saran Kiprus. The one loft 1920, the other 6631.
it muft be confeffed, however, that Lady Pace collected fafter
than the poor woman whofe cafe I have related.
I come now to {peak of the diffection, and to make fome
obfervations on the whole. On the roth of Auguft 1783, the
poor woman died; and the following day Dr. Dacx, an emi-
nent phyfician of this place, accompanied me to open. the body.
I firft drew off 78 pints of clear water: fuppofing, therefore,
all the water to have been taken away at the laft operation,
then in three weeks fhe had collected 78 pints, which is more
than three pints and a halfin each day : a quantity far exceeding
what fhe had taken. I then opened into the cavity from which
the water came, and feparated the fac from the peritoneum,
and found the fac had arifen in the ovarium of the left fide.
After this, I diffeéted out the uterus, with the right ovarium
in a natural ftate, and thus obtained every part neceffary to
fhow the difeafe, vzz. the uterus, the right ovarium found, and
the left enlarged into an immenfe pouch. The cyft itfelf was
not very thick, but lined in almoft every part of it, but more
efpecially in the fore part, with {mall offifications. The peri-
toneum was prodigioufly thickened, and thus, by its additional
ftrength, became the chief fupport of the water. There was
fomething fingular in the fac itfelf, for it was rather two than
one, from there being an opening in the fide of what appeared
at firft the only cavity, which led to another cavity, almoft
equally large with the firft, fo that if all the water in any ope-
ration had not been evacuated, it muft probably have been
owing toa difficulty in its paflage from the fecond into the
firft or more external cyft. From the fize, however, of the
poor woman after each operation, it is evident, that in her
there being two facs did not prevent the total drawing oft of
Wor. LXXIV. Qqq the
476 Mr. Martineav’s Account Of, Stes.
the water. The other vifcera appeared all in a natural flate.
‘The inteftines were quite empty, and puthed up under the ribs,.
fo as to have left but very little room for the expanfion of the
lungs within the thorax. The bladder was contracted, or rather I
fhould fay appeared leflened. ‘The kidneys were healthy, and
both ureters in a natural ftate. The fac is in thé colleGion.
of Jon Hunter, efq. |
In reflecting upon this cafe, an obvious quefticn. arifes ;.
from whence proceeded this immenfe colle@ion of water ?
At different periods of this poor woman’s life the quantity
drawn off, without confidering the urine fhe made, was
much greater than the fluids fhe drank, which appeared from:
meafuring whatever fhe took. It appears then pretty certain,
that this {uperabundant quantity muft have been taken into the
body by abforption ; and if we allow the bodies of animals to:
have this power of abforbing, which we very well know vege-
tables are poflefled of, it will account for many appearances in
the animal ceconomy. This poor woman collected fafter in the:
wet moift months of winter, than in fummer.
From all, this happy conclufion may be drawn, that although:
human art is at prefent infufficient to the perfect cure of difeafes.
fimilar to the poor woman’s cafe I have related, yet nature 1s.
continually defending herfelf from fudden death; and fuch
relief may be granted as to protract life a long time without
much pain, and often with intervals. of great eafe and comfort.
=e
i PO HNN. aa]
XL. Methodus inveniendi Lineas Curvas ex proprietatibus V aria-
tionis Curvature. Auétore Nicolao Landerbeck, Mather.
Profef: in Acad. Upfalienfi Adjunéio. Communicated by Nevil
Mafkelyne, D. D. PF. R. S. and Aftronomer Royal.
Read July 1, 1784. : -
PARS SECUNDA#
URVAS, ex proprietate variationis curvature invenire,
indice per functionem coordinatarum cujufdam expreflo,
problema etfi indeterminatum ett ; juvat tamen ad curvas cog-
nofcendas, quum facile et {ponte fefe offerunt conditiones deter=
minantes qui rel conveniunt et que in caf quovis examini fub-
jecto locum habent. Quo confilio et qua arte calculum inire
oporteat, ut et hee et his affinia peragenda fint, que ad curvas
ex curvature variatione cognofcendas pertineant, per theoremata
que fequuntur, exponere conabor. |
THEOREMA 1. (Videtab. XXI. fig. 2.)
Si curve cujufdam LC index variationis curvature fie T,
radius curvedinis R, finus anguli BCD p, pofito finu toto 1,
arcus curve LC x coordinate perpendiculares x et y earumque
fluxiones dp, dz, dx soy (ey
P> 3 ? Td pe
: ax dz d,
Quoniam dy= ~ Rap et dg= -—S habetur S. = —f
Vimp A siti Pe
* See Vol. LXXIII. p. 456.
Qqq2 :
478 Methodus inveniendi Lineas Curvas ‘
et quum dR= Taz erit R = 7 Tds et fubftitutione “ = =
ST de
Ene
Vvi-p :
Cor. 1. Hine obtinetur = — dp, 2 = T= et = =
dp
Cor. 2. Si Tangens anguli BCD per r, Secatis per s defignen-
tur habetur — = ene Wu ef (Le
: Tdz itr fd sV Fo
Schol. 1. Ex hoc theoremate facilis deducitur methodus gene-
raliter calculandi variationem curvaturz curve cujufcumque.
: Jf Az x d / aire
Nam uf haz) = a , quantitas vero rae) datur, data
a _{ = Z fune-
inter x et y relatione. Sit valor quantitatis =
I
tioni curve %, [Tas Z et fumtis fluxionibus Tds = Zds qua
TRG &tioni ipfius z. Si valor dantitatiee =e er
=Z funétioni ipfius 2. Si q ¢ i ae per.
p expreffus, erit fT == P fumtifque fluxionibus Tds =Pap et
= qua functio eft quantitatis £, in poteftate femper eft
dp .
~ per exprimere.
PG, p exp
Scho/. 2. Hujus etiam theorematis fubfidio inveniri poffunt
“ae
curvee ex data relatione inter T et z, Retz, R ety, et R et p.
Sienim fit T= Z fun@ioni spate erit {Tas = [Zds + A,
di ‘ 4
vi theorematis ——_— = aa as oa P - €{ integratione
Fara = ee
eee Mier ny - Pofita +C=4 et N nu-
JF fZaizta T= i= Z+A
merus
ex proprietatibus Variationis Curvature. 479
merus cujus logarithmus hyperbolicus 1: habetur \/1 —p° f=
wed tan mb t NOV Ti md
2%—1 2
» que funétiones funt
e e s s, : | ” e
quantitatis z, quibus pofitis Z ey oY 1—Z’ refpective proveniunt
x(= fayi-p)= fZdzery(= [pdr)= fai 3
quarum alterutra curvarum indoles innotefcit.
SiR=X funétioni abf{cifle x provenit “~ (—-2 ) ee.
Pp = (= z dp et
. - i dx a UNL
integratione X (=C Je) =p unde /1 —-p= ce sD er
ee pax
y( =f Ge ee =f 5 Te
Et fi R=Y funétioni ordinate y, habetur 2 GS o = =
pd Ip . ° : te dy 1a 2
Vea? et integratione Y (= [2+ ©) = VF —p’, unde p=
Vr l¥ ot (af BF) S72,
ram curve.
Hinc colligitur quod quoties Taz perfette integretur et
Ty alee exprimit natu-
ve Tae obtineatur per arcus circulares dum aut f Zdz aut
ZLdz+A
ye dz Ji _F abfolutam admittat integrationem, curve erunt
rectificabiles, et algebraicze, fi relatio inter + et % vel inter y et x
in relationem algebraicam inter x et y permutart poflit.
Evidens ctiam eft quod fi X fundtio eft algebraica quantitatis +
ax
Live d
vel Y quantitatis y, et non folum ¥7 vel 2 fed etiam
Xd (ad
=< vel No)
ae / ee
dunt algebraicz, alias tranfcendentes.
quantitates perfecte integrabiles, curve eva-
Exempl,
480. ‘Methodus inveniend! Lineas Curvas
Exempl. 1. Invenienda fit curva ubi variatio curvature T=.
2) Bu; 2 Se z he PR te Lee
BLOETATAL eee. Lt fimphicier -reddatur’.caleulus; poner
aii Z 3
avo ie ae
3 Ss . é pens e4
- “2 z_ O42 ea bap
. bar 278)" =4 et at=b erit = - = ie eee te Mee Ze
18 VO u=4o.
ct [Tas ivan a2 Gt ‘conftans ize At
Téz=——__ = + A; fit conftans hee =4, quod
accidit evanefcente we Waza = 0, abetur 7 per — theorema
du /b duSb 4
SG = = et integratione ae : C= = j
“he re isa S Vile .
5 cUjus zquationis Paes guum fint arcus circulares
Te
4b a/b
quorum finus ¢ Oe —p =——— et cofinus p= 7, » pofito arcu
conftanti C=o, ebtinetur y (= Spas) =f du /b eB)
Yu—4b Vb 4bhV/b
a nai oa a pofita y=o et w= 46, atque (=
du ugh hu asl
fads/i—p a = [= aia 3 ES a quibus zequationibus ex-
terminata w et fubftituta a habetur y* = ax° zquatio pro parabola
~
ccubica.
Exempl. 2. Si fit variatio curvature T= erit " Tas (=
a
f2® aU AEE it Ze ae = qerit conftans A= a, atque
E a
; . ] : ;
vi theorematis os = (= =) == Pee et Te
a 7: Taz V1I—p
dz
Jz —3+C= “pa = pofito arcu conftanti C=o cateri
a Pe V1
funt equales corumque finus et cofinus, unde /i p=
a . en Cae Zz
aa et dx (=dz I-p)= ————— et d =
» P V a +2 \ v p) Vg? ly ( a
2 | pas)
rae
ex nla V artationis Cu rvatura. 481
ariam.
“pdz) =
co. 2. Ot wet curvature T=
a—
ss =, evadit ws Td
2a42Z—
=r r theorema Les az
=f 2az —2’,, per theo —___— ae ee
~«& > p Vie ie ‘igi Tdz ar:
“per integrationem ifs ¢ gy ue dp —, fi arcus’ ille
V 20% — 22 Vio
conftans C=o, ceteri funt oy eorumque finus et cofinus,
quo me) Paes, pa ety (= | per) = Le. =
2az—
= eequatio pro ee ordinaria.
NY
THEOREM QA TI.
* Manentibus antea adhibitis denominationibus erit ff
yt J Tax
ia AT
VI— ae ;
dx
Quoniam 4 = “= —dp, erit dividendo: per Vie — p’, ae
-~_#_, Propter 1 : /1—p7:: CD(R):CF=RV7-(,
. Veg
fed dz: dx: Vde > Tdx, que fluxo eft ipflus DE, quare-
me [Var unde CF= y+ [Tay qua pro RV/1 — #? fubfti-
dp
tuta, prodit ———— =.
ae eh aa Vip
Cor. 1. Quantitas dy+ Tdx femper eft perfecte integrabilis..
ce ddueV 3 —p Mi pdx a id pax -
Nam Tay = a ae et dy= ae unde ae 1 gsi
Vi dsVi-p
eS et integratione y + f Tar= — = ane *
Core.
482 Methodus inveniendi Lineas Curvas
Cor. 2. Dicatur femichorda curvature CFF, obtinetur
am dp a = Os Ne
fy oer. Se
Cor. 3. Si Tangens anguli BCD per 7, Secans per s defignen-
d. a d.
eur habetur {fee ep
yt J Tax ony yt S Tax Ay aaa
Schol. 1. Per hoc theorema via etiam patet calculandi gene-.
raliter variationem curvature. Eft enim y+ ie Tdv= —
dxvV 1 —p ° dxV ip °
= quantitas vero Ee datur data inter x et p rela-_
. . e e dxW 1 —p” e e ery
tione. Sit valor quantitatis — eat aes X function: abfciffie x
gequatione ad curvam inventus, erit ye Tdx=X-y et fumtis
fluxionibus Tay = Xdx — dy, qua in Oe = ubi tam X quam
dy : : : oot eee
7, funt functiones abfciffe x. Si valor quantitatis - 7 —F
=P per p expreffus, erit {Tdv =P ~y fumtifque fluxionibus
Tae = Pap —dy, qua T= ty are ubi = fundtio eft quans
nat bae dp aad
nam — per p expr :
titatis p, nam — per p exprimi poteft
Schol. 2. Hoc adhibito theoremate inveniri etiam poffunt
curve, ex data relatione inter T et x, F et x, F et y, Pee 2,
et Fet p. Pofita enim T funétione quantitatis +, patet per —
curvarum quadraturas, aut perfectam aut imperfectam quanti-
. . . . . . | u
tatis Td obtineri integrationem. Sit [Tdx=X+ f Xde
functioni vel algebraicee vel ex parte tranfcendenti ipfius +,
: hs be wu ;
cujus terminis homogeneus valor ipfius y= f Xda capiatur,
{que ejus indolis ut fX + Xdx, vel quod idem eft y + {Td
3 A+
=
ex iia Variationis Curvature. 483
X +4 of sues integratione abfoluta habeatury- permanente
shi] Tis! weak = X* perfecte integrabili. Per theorerma deindeé
d. ds 1,
habetur : =——_)= eee pet integra-
x4 SX 4 Xue y+ J Tae eae
: d j
tionem ia ee C= eG Apematur
Ki f X+Xdx saa
d: ep. ;
= — +C=et N bafi logarithmorum hyperbolicorum,
“x4 /X4Xde
i nit a NA? ‘ nev? - Nowe 1 5
2 pals a5
GHG / 1 =D Se CUD re aay PO Ait ert
et f igitur funt functiones ipfius x, que fi ponantur Vix —
tll
Xd. ;
et X, habetur y (= Sue J Deu er : Paty , equatio qua curve
internofcuntur. -
on ire pattie Eee quantitatis y erit “per ‘Cor. 2.
By pd a oe
= (= +)= aL ~ et integratione f+ log.C = log. /1-p,
dy may ;
ponatur. | Yo net N oe aera bafi, erit facto ad quan-
titates abfolutas tranfitu CN’ =/i — p*, par/1 — CN* et x C=
dy 1p" CN‘ ay nO es
LS z Ss =) = ee on Tape zequatio quae indolem curves indi-
oitat.
Jalery pe VERE : ae 1% Gi
Si F = Z functioni ipfius 2 erit a Ga ) See = et integras
P
Zz
- eM I=) 3 az
is ite a iat 08 WS et
tione 7 = +]og.C= log. |5=%, et i fF=k = et N bali logarith-
I 2 O2N2*
mica —habeturips 4 ery Eid: “= a pieoaidaia =
I a CAN:
curve cognofcuntur.
‘Vor. LXXIV. ent Conftat
484 Methodus inveniendi Lineas Curvas
Conftat hine quod quoties X + Sf Xdx perfedta integratione
a
dx
habeatur ope
per arcus circulares dum
\ tl
x2 fee ai
lutam admittat integrationem curva fit algebraica, fi vero aliter
evenerit tranfcendens.
CN "dy
—C?N?*
admittat integrationem curva eft debris in aliis cafibus *
4
¥,
* 'y
h
|
Quoties = fit integrale logarithmicum et — abfolutam
tranicendens.
1—C?N?4 d=
Et quoties [2 per logarithmos inveniatur,
Z
k
=apagt a : 2CN' dz : 5
lute fit integrabilis pariter ac ———— curva eft algebraica, alias
I+CN
tranfcendens.
— §s_—>»-———
2. P= ane oe
Exempl. 1. Si fit variatio curvature T = erit
arb
Peta = oe ee =*) = aveas sVe—e hve me
. oa Te oi eee ee ey ee an e
[YY Gk OWT .
Paka delle —— HE ponatur y= oe habetur y+ Sf Tdxx
a
+45)7 2 ae: 2y ir Fae Bf 4 3hd
oe, “adhibendo theorema —__ aa (=
arb 6 —a*x V a—x
3
—=_) = ane a ce et integrando f=. +C=
Te ae Mi — a+b — xP Vg — x
;» cujus termini funt arcus circulares quorum finus
VviI- 4
(tA: oe b ¢
av « :
J/1 — p= = ee GE cofinus p = 3 ee evanefcente ‘ ‘
Vitzo —a’x" a .
: dx 2st bv Ge
arcu conftanti C, quare y (= {2 —)= l\w= — bv at j
Je 4 ( Vvi-?" We =) MNT ag My
et in hoc cafu curva eft ellipfis.
4 Exempl
ex proprietatibus Vartationis Curvatura. 405
° e ° e VA i .
Exempl. 2) (eit jam variatio curvature Teo erit
i x
Sf Td = — ty v= et pofita y=
; : v9 se
fecta integratione habetur 'y + of des —r - TLheore-
V oax+ x? PER
matis itaque auxilio erit 2" (= Hei BPA hy
; atxV 2axtx ~ y+ f Tdx ve ae?
es e aie
antes Fatione f= =e SF ea AG S= » fi vero arcus ille
aLeV 2ax+x"
conitans C=o0 ceteri funt zquales boinc finus et cofinus,
ee V 2ax +x pax adx
unde /1-p* a aL ae ty( SAS )=/FE=:
gequatio indicans curvam effe catenariam.
(TB EoOR © M Avy BY.
Dicatur cofinus anguli BCD 4, pofito radio 1, cexterifque
eee acl
Vas Coe
na dg
Eft enim = “q> qua per /i—g- q- ‘divifa, dat 5 SS
hie oe OD (i) .CG= RTP fed dz dy.
Tdz : Tay cujus integrale eft AE= ft Tg, unde CG =
AE — AB) = JI Tdy-x, quaproR /1—g* fubftituta, prodit
ie
S Taye Yi-¢
Cor. 1. Semper Tay —dx admittit perfectam integrationem,
manentibus denominationibus erit
WV T=
Etenim Tdy= lay At Ct dues Las quibus Tdy—dx =
aq Vi-¢
ddyVi-g _ _ay Ce ete Aa, eae
Fug oy ae © ecg rations Pe Tay — oe
Rrra Cor.
| Cone diaee Dita ea curvature: Wee) _G, hal tu
dy dg ® de iq is Zee 6
—-——— » ees em ee
Go Vis ay 1 ga age) % eT ¥ a
4 hee - Sams Ne Ledeiaitete een. ERS) Ve
Cor ara catur cotangens angult. BED- i, an re Uv erit.
gas poe presi dnb = Sd Ge Yi titades nero: ao) ar. ae
Jf Vdy—-« os aa yf Tday—% uv i
Aya
Sek of. 1 Quoniam hs Tay =f= oot atures datarelationé
eee
miter y City, tt a weet: e =¥ function: ordinate y pi ag:
ae
Dees furntifque fuxionibus Tdy= i dx sae TS dy
dy ue
fun@tioni ipfius y. Si autem = ag inca ipGus 5
erit f Tdy= OF et fumtis fluxionibus Tay = Qadg - dx, qua
habetur Fete $2 erg. a :
Schol..2. Hujus Aieeee atic auxilio elicere licet curvas data {
relatione inter ‘I. et y,.G et y, G;et-x,,-G et x, ct,Get ge |
SI enim fit T functio ipfius y generaliter {Tay = == + f¥ey +A,
que functio eft algebraica ipfius y guoties f Yay abfolute fe
poffit. Affumatur x= ['Y dy, tali ipfius y funtioni ut non.
folum f Tdy —x=V¥4+fY¥4V¥ay fed etiam, re Sry
idage
| . . . . .
1-Y°* abfoluta integratione pee provenit vi theo-
: ay
rematis a
Ve fl Huy pia
a ;
oferty ae ae — Te OC >= : Pofita ze *
“ie SX 434A oi + Ji Paghs
“a yntl \ spite Mint Na
FC=/et N bafi logarithmica erit g =. 5 aL et Ji-g
a es a8 ff, EC ratione »
=f vot ee 3 me
2 eS
ex proprietatibus Variations Curvature. 487
hi/ot wiW—
=) a ee que fan@iones fant ‘quantitatis % Quibus
2
=, Y et rv EWS ne, (= vie ‘aa lg fee za bo nae
V1i-—g s/ us 4
tio quiz igeleen curvarum indicat.
Sor GX fangioni ipfius % erit per Cor. 2.5 ie (= = =< ,
sia
ee : ; d ne
et integratione log. CN’ = fz log. Cc =log. +. fy Je
! "a vere g.¢ ( 43 ) iret ae
I JSON a 5 iy AL plea
=f, ;cxinde ee rer nine ° iy ake Vi et y Ce
ax
= Wa oe ch uz Curve naturam indigitat.
ONY —
ae SU g
Si GZ bine toai i ip x erit FE fo = i = ta, cE integra-
red,
rane log. ChE 4 C) slew pa i [fF pea unde g
22? aaa iy pee ‘
c ee a aCN? ges Sa) 2 fermi de me
B43 C?NP oq J. CeNe 2 PEC2N*
= ie Cc} i
fde/ oie aie curve »gognofeuntur.
JEacce shin quod, quando valve -algebraice habeatwe
i
- gy
—, per quadraturam egee ofits oe Chalk
pha 2 Hisdd ee j at vei . Da
obtineatur algebraice, curve evadunt algebraice, fecus vero.
tranfcendentes. aie Dae Se
dx az : aig: :
Quando / a vel SS — ae per logarithmos, et
de urna
Po Coe 03 vel tam f Nad itn, fae abfoluta in+
C N — eae é
2
tegratione, curve erunt algebraice.
qu
r+C'N
Exempl..
-
433 Methodus inveniendi Lineas fares
Exempl. 1. Sit index variationis curvature T = ~2 ~? exit f Tay=
yA f ae illa conftans A= ei evenit quum
a ;
2ady ;
ae nN
bi
(= _7_) = at et integratione f° 2 aed aah + C= fare
' i Tdy=x I? fo
cujus zequationis termini eee fint arcus oe quer
s 2
[la=s ct y=os fumatur «= + erit vi theorematis
| : :
arcu conftanti
nue y= = ck eens (7 0
i
Va + 4y Wa bag
€=o, obtinetur x(= elds es Serie bade pro parabola Apol-
loniana.
Exempl. 2. Si fit T= [= a
habet Tay=
: aay abetur f” y=
Va —y* +A, fi quantitas illa conftans Ao quod evenit quum
7 ‘ V Gay :
[Tay =0 ef y=a, et affumatur ne) oven, evadit per
theorema = a3 rere lan et per integrationem
Wraps ae os —<* i an g : P 5
qq
- C= / —_, quorum arcuum finus g=
~s Tat ale
ae et cofinus /1 — se fi conftans ille C=o, atque inde
4 dyV1—y
dx aoe wie qua patet curvam effe tractoriam.
THEOREMA IV.
Dicatur fumma tangentium angulorum HCD et BCD H, et
differentia ea waht HCD et ae K, retentis
dx oe ___ 4
ids Vi-# ct Ts Ky Vimy
Quoniam
ex i retonbien Variationis Curvature. 489
Quoniam dy = qr erit dy+Tdv= T+ eS dx et quum
2 T + mS - habetur dy + Tdx=Hd. Eodem modo quum
dx = cerit {Tay - Ae oper k= TOA,
unde J Tay —*x=Kédy. Per "yee eae 2 et 3 provenit
a Ag dp t aye da
a Se = ee
J Hae Vise Lf iey Vay
Cor. Si fit ut antea tangens anguli BCD 7, cotangens t, fe-
dx dr ax ds
—s
= maar cans
S Hax 7 ae JS Hax (ae -
cans s, et cofecans v, erit
ie eo Et AE all dv
pres el aay pn
Schol. Ope hujus theorematis invenire licet curvas, data rela-
tione inter H et ~ atque K et y. Itaque ft H=X ae
ipfius # erit ch bign = =f Xdx+ A, vi theorematis (=
a
=A et inte ratione f-——“* Cea Pee
Ta> Var, 5 Je ek | Va.
Pofita Vs =e roe C=m, et N logarithmorum bai prodit
x
an pe Mi NTM/ 1 N#/—1 + ee “
J1-p Thi arg Sk PS z »quibus func-
s X ° ° e { ! °
tionibus quantitatis x pofitis J I—X* et X provenit zquatio-
y = )= X2y
Vin Vr oe
Si K=Y fundctioni quantitatis y, eadem calculandi ratione-
naturam curvarum exprimens..
F oe a
habetur x (= ve ar F —= + xquatio qua curve cognof--
am VAG
cuntur.
Quando:
PRR Sate’: Aisne,» A ." - , Mies me the abr esn Nye) Ke be rave Py) |
Wierik , { (. j ri ‘
, . - ‘ :
4 ; \ ty Ea
ae somupsibodis Sodan Da : a “
~ Quando fs Ka vel f Ydy abfoluta i integr ations f pales vel 4
Yay +- A
ay ¢ 4 si Pe bai g
Ary rune en tuba ty Kade sine og el ie apes Fe :
fe ere per ‘ye@ificationer citeuli, a pee ve Yoo!
1 0) fo)
; | es | ae ee f
integratione perfecta obtineantur, scurva eft algebratcar Ws
Bxempl, 1+,Si it Hs 5 erin ae
aay x
1 : Af 6 THe%
fita A=o habetur per theorema =——— Yee aot are pd oe ce
a iny ie | hae a wel,
(a idea .
et per integrationem f =———_ + C= i cts termini
at4eyx VI ve Bi
- ‘ “7 a ai? ¥
quum {int arcus circulares quorum finus JI ey aa et
ay "
hanes oo eae
cofinus p= ofita,\O=0, obtinetut = \ = Jax.
p= j=) iP oe Ava Ee A 3
jue parabolam A polloniam exprumit.
4 94
Exempl. 2. Sit H= ee ork eee et =e Fit A,
at V a x
d. d.
et fi ASo, per theorema aM, =(= e te) , es et
re a a a ae _ ST Hd VaR \,
per Nay a SAR -{=4 ,ethC= “te
x? 94" V g*— x* Vp 2
J/i-p eee = 0S ety (= fF Ss Veae
quatio pro curva finwum,
Exempl. 3. Si ft. Ke
=a A,
= 7
a’ dy os ay 1M Me
a+ ay a+y igonth kaj a Vipg
. 4 . ad; g
interratione § ——————= 2 Gee Shas ua ——
= Shey vay VI Ee Fars 1 Ve sede
fi A=o habetur per theorema -
Rie ae, Va ‘: 's Gay
Mig =— 34) fC o. aie 2 _ fe aright gt
apap” (SSF ™ Suthido
gequatio pro epmeie eequilatera. ae
ex proprietatibus V artationis Curvature. 491
| Exempl. 4. Sit = exit [Kay = A-V/a-y et fi
~
=
A=o, per theorema — ——— et per integra-
7 | “Fag a
iG ae
at a gu === quaq= = oe gee gt =
a: dyV a* —
= et dx (= oe = Wer
=
que Tractoriam exprimit.
THEOREM A VV.
_ Defignetur produ&um tangentium angulorum HCD et BCD
per U, et angulorum HCD et CKB per V ceteris manentibus
Be a EE op i = A
SJ Udx—x Bin EY aVdy 55.9
Quoniam dy= ASS ctU = 5 ent Way ( = 7) =
A 5
Ud, et integratione Hb Tay = fe Uds qua ft Tay —*x=/ Udy — x.
Tq 7d:
fet V = 2 crit Tae (=5 Bg) —=) a
Pgs VI-g Vig
Vay, f a= Wi Vdy et y+ J Tdx = y+ f Vdy. Theoremate
Et quoniam dx =
d. a d
ace emodi = ep 2 eT
ft Uds —x P yt J Vay q
Cor. Si anguli BCD tangens, cotangens, &c. defignentur ut
d: d d a >
mee a iach ee gl a ee
J Ude—x rt am y+ J Vay fsck ot
Schof. Per hoc theorema curve inveniuntur ex data relatione
inter U et x, atque inter V ety. Sienim fit bia funétioni
ipfius erit fUdr = Ages AN, Sper theorema p= ee (=
aes = — 2, et per integrationem 77 + log. C=
Vou. LXXIV. srt log.
492 Methodus inveniend: Lineas Curvas a
= d. e e é e
log. : ; Pome fee = net N bafi logarithmica, erit
Aa %
pr eis ¥ Ont 2n2 : pig
S0ON%; Zier Soo! et = |
: ee a oR
of ie qua eequatione curvarum indoles innotefcit.
oe 2n
Si V=Y funétioni ipfius y, eadem calculandi ratione pro-
ren dy CN"d
So ae (= [ie i “)= = Wf cee a qua curve cognofcuntur. |
vig CN
Evidens hine eft quod swotiesf Sd vel [ Yay algebraice
dx dy 1 i t
hg Paiva; ape on Tages ogarithmos, atque Nig aes
wise 4
obtineantur, curva eft
algebraica.
Exempl. 1. Si fit U=3 erit [Udy = 3x+A, fi vero f Ude=
ed quando x =oeritA+ =< et fUdw — x =o*. Per theorema
. dx dp . .
ioitur =-— “ et per integrationem log.
gitur S ( "Tea 5 ct OP g log
/a+4x+log.C=log. -, pofita p=1 dum x=0 log. C= =
: : /
~ /4, unde facto a losis tranfitu Fe =: = 9 ie
rare oer gl = 5 oe “SIS at en )= vas
eequatio pro Parabola dessin
See x 3 Ws
Exempl. 2. Sit U=—* erit [ Udy == sey +A, fi auten
J UVdx =o et YS erit A=o a f Uden ts Vi
Tena ie es 2, et integratione
4
I
igitur theorematis erit ~
a =T er
4 log,
eft Elaftica,
ex proprietatibus Variationis Curvature. : - 3
log. pie. Jana t log. C= log. 2 qua p= 2S", Vip
Va
__ pdx _ __ ax dn Vas — 93 — x3 :
et y (= SAS Paar = oan zequatio ad curvam “aH
Exempl. 3. Si V = a ~ crit f Vdy=A—2 j pofita {Vay =o
_ety=oerit A=oety+ ie Vdy= 2 - Per theorema obtinetur
_2dy --
="! et per integrationem lo 4+ lor. C=
a ee ie yi - § gy B°
log. 7, fi g=1 et y=aerit log. C= —log. a’, unde Gao
ay ceded eat i Lg
/i-g = Y atque ee Je) = curva ergo
Exempl. 4. Sit v= erit f Vay =A— a fi [ Vdy
o: — 3a et y=aerit A=o, Cn oer ‘The-
f dy
orematis ope habetur — 22. (= Jao et integratione
: re a Vay A
at oe C=log.g, fig=1 et y=o erit log. C=log, a
log. eae
ay
et Jak mle eg IO ck de Be
a : . :
ey eequatio pro Logarithmica.
4 f:
THEOREMA VI.
Dicatur ED L, et AE M, retentis praeterea adhibitis deno-
minationibus erit 2 = dx-et = = dy.
Quoniam dz: dx :: Tdz (dR): Tae habetur dL=Tde et
Sf{f2 dL,
494 Methodus inveniendi Lineas Curvas
= du. Et oe dz: dy +: Td ~ R) : Tay ——7
ay ae ae
Cor. Quem Tay = Ude. ct ee = Vay... exit fubsticutione
a = de f= =="dy .
Schol, ec adhibito theoremate inveniri poffunt curve data
relatione inter T’ et L, T et M, atque inter U et Met VetL.
Ponatur L=T fundtioni quantitatis T habetur per theorema
av
ar
Curve deinde per theorema 2. elici poffunt.
' .
aT
‘a2 — dx et integratione op tC =xqua T per + datur.
SiM=T ipfius T funétioni, habetur eodem modo T per y.
Si M=U funétioni ipfius U, obtinetur U per x, et fi Ln
tioni quantitatis V, datur V pery. Per theorema deinde 3. et
5. curve invenuntur.
Evidens quidem eft quod curve effe non poflunt algebraicze
dL, dM dM
nif if > Sf SF vel vel f , obtineantur integratione ab-
foluta.
: i GN TdT
Ex capa !. sunt , erit dL= a et per hoc theorema
TAT J T? 6
a wat (a =)= dx et integratione ae +C=y quaT= ee ft
Le O. aL theorema 2. reperitury =,/@x, «quatio pro Para-
bola Apolloniana.
Exempl. 2. Sift M= - [DS crit M=-——2 et
2. T7) ee
: TdT a
ope theorematis - —“_“__ (= i) = dy, et integratione —S—
a. i+ ry 4-14T
+C=y, qua fiC=o, Tigh “#8 . Per theorema 3. habetur
ak
‘ : : /
ex proprietatibus Variationis Curvature. 495
dy7
dx = — aequatio pro Cycloide ordinaria.
Ay
Exempl. a L=-a/VeritdL= -
adV
Gear = )= dy et integratione oe 4c =, eta € =o, ha-
betur V=- 7p et deinde per theorema 5. dv = —— qua con-
ftat curvam efle Tratoriam.
THEOREMA VII.
Dicatur ut antea CF F et CG G, et fumma tangentium an-
gulorum HCD et BCD, H, et ne tangentium angulo-
rum HCD et CKB, K, erit ay choe T=)
Quoniam dF a Td) =Hds ct dG (= [f'Tdy-x) =
Kd provenit = eB de et 2 dy:
pone dyVy— 9 Sie
Cor. Quum F= -“ 47? et Ga2 ae provenit divifione.
ap _ ap
dF dp EC wha,
a —————— tf u —_ = >
Y PH ar Viegas! WGK Ly Tae
Schol. Auxilio hujus theorematis inveniuntur curve ex data
relatione inter F et H, Get K, Het p atque K etg. Nam fi
| ° eile: ! . ole _
fit F=H functioni pi H, vel G=K fundhoni ipfius K, ha-
au
fe ape theorema — Ti
toe
. aK 7. dG :
qua H per datur. Eodem modo —— a =) = dy et integra-
|
dF : . dH
—— )=—dx et integratione f — + C=x.
a) it gra a +
]
: ak . 1
tione Jf = + C=y qua K per y obtinetur. ‘Theorema 4. ulte--
rus progredienti viam monftrat ad curvas inveniendas,
Patet
496 _ Methodus invensendi Lineas Curvas _
! §
Patet quod curva non fit algebraica nifi = vel | as
antur perfecta integratione.
Exempl. 1. Si fit F=~-2— habetur per theorema —
| Vi+H?
adH Dae eas e if oH ae
=I (=F) = dx, et integratione F==——; +C = —#* quaH= —
=—=, pofita C=o. Per theorema deinde 4. provenit y=
VG — x
/a° —x° equatio pro circulo.
a. H34+H*+6V~VH?—12
108
Exempl. 2. Sit F= , erit per theorema
a. H’?—6+HVH’?—12.dH (= dF
30Vv He — 12
a. W—-6+HVH 12
72
, unde per theorema 4. prodit y=,/ax zquatio pro Para-
H
+ C=, et pofita C=o habetur H=
a+-1awv
2Va Vx
bola Apolloniana.
: ah Ke
Exempl. 3 Sit G= = adlbh, BUGS
4
‘ aK
erit per theorema = ize
dG . . aK 2
<<) => et integratione 5 FC =I i Co K=~ unde
d’ ‘
per theorema 4. dx=“, qua conftat curvam effe Logarith-
J
micam.
THEOREMA VIII.
Dicatur ut antea productum tangentium angulorum HCD
et BCD U, et produétum tangentium angulorum HCD et
. <tr zx fee ; dG
CKB V manentibus reliquis denominationibus erit =) dx et
Quoniam
btine ° .
“-\ = dx et integratione fata —
ex proprictatibus Variationis Curvature. 497
Quoniam G = A Tdy —x ent dG=Tdy — dx, fed Tdy =Uadx,
unde d@G=U — 1dx et as =—dx. Eeodem modo quum F'=
y+ [Tae eit dF=dy+Tads, fed Tde=Vdy quare dF =
1+ Vay et —— = dy.
. _dyWV 1-9 ae dsVi—p
Cor. Quoniam G= ae F= Sra hope fub-
att : dG d d¥ d
ftitutione debita ———— = — stk ae ae si
SU pe ey) 2
Scho/. Ope hujus theorematis indagantur curve data rela-
tione inter G et U vel inter Fet V. Nam fi fit G=U fundtioni
quantitatis U vel F= V fundtioni quantitatis V obtinetur per
|
EL dG ) se
| theorema in cafu prion’ -— (=,7—/=4% et integratione
]
dU
Gy
dF
5 (=5)
+C=x,qua U per x habetur; in potteriori
= dy et integratione cai C=y, qua V habetur per y. Per
theorema deinde 5. curve cognofcuntur.
Datur etiam per Cor. 4 inp, ct V. : Ms et confequenter T
et
Tice a
in p vel g, nam U=
;
° e > a :
Conftat hinc quod curve non fint algebraic nifi aa vel:
dv 7
ff ay obtineantur aNzaiuelone abfoluta.
Exempl. 1. Si fit Ga — erit per theorema — (=
2)
— J
dG — Av = 5 RI DEN. an a”
“—) =dx et integratione log. 1 -U+log.C= — et iC=—
log.
498 Methodus inveniendi Lineas Curvas
Ae) NOS he
Se ax —
J Za ate om a.1—U — 2_-oN¢e si
log. = == cb ae NE qualia - Per theo-
az
xe
remadeinde 5. habetur ¢y= qua conftat curvam eft Loga-
rithmicam.
250 ay aa V+2 z
Exempl. 2. Si fit T = aS erit per theorema
adV dF aVV +2
aV3VV+2 (= TeV
—2a Vy — a"
a
2
} d al
ya m3» ct per theorema 5. i ae » equatio ad cur~
vam cujus conf{tructio a quadratura hyperbole dependet.
THEOREM A 1X.
Sint LC et /¢ duz curve eandem habentes Evolutam QD,
dicatur radiorum ofculi CD cD conftans differentia cC 4, curve
Jc variatio curvature S, ceterif{que ut antea manentibus erit
dR dp
as Pies ae
uoniam radius curvature DH evolute fit RT =R-—AS,
; I I RTdp <a
rit ——— —=__, que per dR (=Tadz)= -——£ multiplicata
erit ——— = 5 que p ( ) vig Itiplicata,
ER db
moftrat effe —— = —- —-—=.
R—4S 1—p
Cor. Si fint ut antea tangens anguli BCD r et fecans s, ha-
dR dr dR d
betur——— spel wont a eyes A
R-—4S I+” R—obS SV s*—1
Schol. Subfidio hujus theorematis invenire licet curyas, data
* t d S R
relatione inter S et R vel inter S et T nam a Rope Itaque fi
ponatur
jay et per integrationem ae qua
av proprietatibus Variationis Curvature. 4g
dR dR
ponaturS =R fundtioni radii curvedinisR, crit 8 - (= 8. )
| : MR cage
dR d, :
= Ag et i .+C=- ars 2) BIE
ae R-bR tare
—= + C=/f et N logarithmorum bafi habetur /i-f re =
as bR ate
wh 1 ynf/-? WW ta Ny = he Ls
Thee et pa ia functionibus quantitatis
2/—1 2
R, quibus R per p exprimi poteft. Per theorema igitur 1.
curvas interno{cere valemus.
{
: ! bate eas dS dR
Si R=S funétioni quantitatis S habetur —=—- (====—
cee R=6S
= > et integratione ae Ce -f{ , pofita
ae ele Ta S Si ara
=a
ds : ae EV —t_ ye at NEV —! + y—er/—
) Pag, erit/1 —p ce Ces
S43 2—vF
quibus S per p datur. Per theoremata Partis I. invenire licet
curvas omnes eandem evolutam habentes.
ak)
Hine videtur, quod curve non fint algebraicze nifi oy =
R- bk
ce
vel —-— per circuli ‘aioatoneta obtineatur.
SoS fs
° R 2 °
Exempl. 1% Si fit S= ** =~ fuppofita d=2, erit pes
P Wiis YWk—a Pi ; P
dRi4a aR dp ye Ate
theorema = = - +-== ef integration
wRVR—a RS Vip 8
eee +C= a a , fivero arcus ille conftans C=o¢
aRVR—a VYi—p fs
© qua R=ap', ct per Cor 1. Theon 1. ha-
erit \/1 — 9°: ~ pis
betur dy = fies zequatio pro Catenaria.
Mon. LX: Tee : Exempl,
500 Methodus inveniend: Lineas Curvas, &e. tS
_ Exempl. 2. Sit s=~ fs =» pofita fa erit per theorema
a ao GR
adR dR dp
= bell SSS ‘g
FoR oe = a et £ afta integratione See zt
= Sos C=e, habetti VJi-p === = et R=
dbo ae Per theorema I. dv = " qua conftat curvam
a Woy
2
éfle Tractoriam.
Philos. Trans Vol L XXIV. Tab. XXL yp. 500.
Philos Trans Vol LXXIV, Tab. XXL p. 500.
om
+
<a:
Ree
ete »
me - *
ee ee pe =
SS == - SF ~~
The
[ sou]
PKS
ENG TS
MADE TO THE
mOyvoAL: SOCTET V
From November 1783 to July 17843
WITHA
Donors,
1783.
Joy. 6. William Butter, M. D.
eames pees Gee
M. Barbot du Pleffis.
Committee of Bethlem Hof- -
pital.
Samuel Foart Simmons, M D.
F.R.S,
/ Society of Arts, Manufac-
tures, and Commerce.
John Strange, Efq. F.R.S.
Le Baron de Marivetz and
M. Gouflier.
CAM ES of the “D°O "N’ OFR S:
Titkes.
An improved Method of opening the
Temporal Artery. 8?
Alfo an Apparatus, invented by Dr.
Butter, to ftop the Bleeding.
Effai fur la Poifibilité d’une Machine a
Of{cillations croiffantes, 8°
An hiftorical Account of the Origin,
Progrefs, and prefent State of Bethlem
Hofpital. 4°
An Account of the Life and Writings of
the late William Hunter, M. D.
F.R.S. 3”
Tranfactions of the Society eniituted at
London for the Encouragement of
Arts, ManufaGtures, and Commerce:
We avrOdee Le $°
De’ Monti Colonnari e d’altri Fenomeni
Vulcanici dello Stato Veneto,
a
Phyfique du Monde, tom, III. 4
Et t.¢ Denors,
178
Nov. ape
| Seeeer’)
-Donecrs,
Andrew Duncan; M_ D,
M. Darquier.
M, Levéque,
M. Sonnerat.
es)
Royal Academy of Sciences
at Stockholin.
Andrew Sparman, M. D.
Roland Martin, M.D.
M. E. A. W. Zimmerman,
M, Joh. Fran. Cofte,
Chev. Marf, Landriani.
Sig. Pietro Mofcati.
Count Profpero Balba.
Mr. de Magellan, F.R.S.
Sig. Franc. Bartolozzi.
M. Aniffon.
= i]
; Titles.
Medical Commentaries for 1781, 1782,
and 1783.
Bbietvsticins Aftronomiques faites A Tou-
loufe, part II. .
Examen Maritime Théorique et Pratique,
by Don George Juan, tranflated from
the Spanifn into the French by Me
Levéque, 2 vols.
Voyage aux Indes Orientales et a la
Chine, 2 vols. ar
Voyage a la Nouvelle Guinée. aS
Vetenfkaps Acad. Nya Handlingar, for
1782. 8°
Refa til Goda Hopps Udden, &c. part I,
oe
Afhandling om Ben-Sjukdomar. - §°
Tabula Mundi Geographico- Zoologica,
Oratio habita in Capitolio Gulielmopo- |
litano, in Comitiis Univerfitatis Vir-
ginie, 8°
Deicrizione di una Machina Meteorolo-
gica. ,
Defcription d’une Machine propre a élever
PEau par la Rotation d’ume Corde
Verticale. 8°
Ricerche ed Offervazioni per perfezmouatg
il Barometro,
Memorie I{toriche intorno gli ftudi del
Padre Beccaria, by Sig. Candi. 8°
An anonymous printed Sheet, in Italian,
containing Obfervations on Chev. Rofa’s
Experiments concerning the Principle
of the pulfation of Arteries. 8°
Defcription of a Glafs Apparatus for
making Mineral Waters. 8°
Quatro Lettere eftemporanee fopra alcune
curiofita Fifiologiche, e Lettera conte-
nente alcuni tentativi d’E{perienze per
dimoftrare una nuova forza efiftente nel
cuore. 8°
Prémiére Epreuve d’une nouvelle Prefle
inyentée pour ’Imprimerie Royale, 8°
Donors.
f soz |
Donors.
1782,
Nov. 13. M. Aniffon.
M, de Romé de I’Ifle.
20. J. Phil. de Limbourg, M, D.
F.R.S.
N. M.de Wolff, M.D. F.R.S,
T. Reid, M. D.
27. Charles White, Efqe
Society of Sciences at Har-
lem.
ec. 11. M. Jeaurat.
Marquis Durazzo,
18. Royal Academy of Sciences
at Berlin.
M. Le Roy.
William Withering, M. D.
M. Faujas de Saint Fond.
"1704.
Jan, §. Samuel Foart Simmons, M.D.
BKAR.S.
Prefident Stiles.
18, Anonymous Author.
Titles.
A manufcript Memoir on the Subject of
this new Prefs, read at the French
Academy, and the Approbation of the
faid Academy. fol.
Criftallographie, 2d edit. 4 vols. 8°
Les Amufemens de Spa, 2 vols. 3°
Genera et Species Plantarum Vocabulis
Characterifticis definita. 8°
An Effay on the Nature and Cure of the
Phthifis Pulmonalis. Oh;
An Enquiry into the Nature and Canfe
of that Swelling in one or both of the
lower Extremities, which fometimes
happens to lying-in Women, 8°
Verhandelingen uitgegeeven door de Hol-
landiche Maatfchappye der Weeten-
{chappen, te Haarlem, vol. XX.
Connoiflancedes Temps pour l’Année
1786. 8°
Elogi Storici di Criftoforo Colombo e di.
Andrea Doria, 4
Nouveaux Memoires, pour l’Année 1780.
3
Les Navires des Anciens confiderés par
rapport a leurs Voiles. oy
Outlines of Mineralogy, tranflated from
the Original of Sir Torbern Berg-
man. 3°
Deicription des Expériences de la Ma-
chine Aereftatique de M. Montgolfier.
vol. I. ,
The London Medical Journal, 4 vols. 8°
Conjectures on the Nature and Motion-
of Meteors which are above the At-
mo{phere, by Thomas Clapp, late Prefi-
dent of Yale College in Connecticut. 4°
Vox Oculis Subjecta. A Differtation on
the moft curious and important Art of
imparting Speech and the Knowledge
of Langudge to the naturally Deaf,
~ and confequently Dumb, with a parti-
cular Account of the Academy of
Meff. Braidwood of Edinburgh. By a
Parent. 8°
Donors.
1784.
i sea 9
Donors,
Jan. 15. Imperial Academy of Sciences
at Peterfburg.
22. P. Camper, M.D. F.R.S.
Feb. 120:
Mr. Thomas Henchman.
M. De Fay.
M.A. J. Reneaux.
1g. Commiffioners of Longitude.
Mar, 4.
Ife
18.
April 1.
29
M, Poiffonier.
Abbé G. Fontana.
Thomas Percival,
F.R.S.
Earl Cowper, F.R.S.
M. D.
Se
M. de Marcorelle Baron
*Etcalle.
M. Mentelle.
Mr, John Sheldon, F.R.S.
Sig. Ant. M. Lorgna,
Le Baron de Marivetz et
M. Gouffier,
——_
M., J. A. E. Goeze.
Thomas Aftle, Efq. F.R.S.
Titles. 7 yi
AG@a Academie Scientiatum Imperia
Petropolitane, the fecond Volume for
1777, and the two Volumes ‘for 7 x
1778. ae
Differtation fur la meilleure forme des |
Souliers. 8°
A compendious Vocabulary, Englifh and
Perfian.
A Tranflation of a Royal Grant of Land
by one of the ancient Raajas of Hin-
doftan, from the Originalin the Shan-
{crit Language and Charaéter. a
A printed Sheet in Perfic Characters.
La Nature confiderée dans plufieurs de <
Operations.
Effai tur les Machines Aeroftatiques. 4°
Nautical Almanack for 1787, ig
1789, and 1790.
Difcours fur la Naiffance de ies
le Dauphin.
Opuiculi Scientifici. 8°
Moral and Literary Differtations. 8°
Notizie degli aggrandimenti delle Sci-
enze Fifiche,
Specimen Experimentorum Naturalium
que fingulis annis in Pifeano Lyceo
exhibere folet Car. Alph. Guadag-
nius, M. D. Phyf. Exp. Prof. Ord. 8°
Hints for neutralizing Neceflary Houfes
at a {mall Expence. 4
Cofmographie élémentaire divifée_ en
Parties Aftronomique et Géographigue,
°
The Hiftory of the Abforbent Syftem, fol.
Memorie di Matematica e Fifica della So-
cieta Italiana, tom, I.
Phyfique du Monde, tom, IV. 4
Reponfe a l’Examen de la Phyfique da
Monde.
Verfuch einer Naturgefchichte der Ein-
geweidewurmer thierifcher korper, 4°
The Origin and Progrefs of Writing, as
well Hieroglyphical as Elementary. 4°
7 Donors.
[ sem |
Donorss
1784.
April 29. Mr. George Walker.
—— Knowles, Efq.
Charles M’ Kinnon, Efq.
Le Marq. de Hauteforte.
May 6, Sir Thomas Hyde Page,
F.R.S.
George Pearfon, M. D,
M. Kleinfchmidt.
M. Olavfen, of Kongsberg
in Norway.
20. Royal Society of Gottingen.
M. Trembley, F.R.S.
27. Rev. Dr. Kippis, F.R.S.
June to. His Mayjesry.
Royal Academy of Sciences
at Berlin,
M. George Vegas
Titles.
A Colleétion of the minute Shells lately
difcovered in the Sand of the Sea-Shore,
near Sandwich 4?
A Plan of a Machine for weivhing the
Force of the Wind, invented by the
late Sir Charles Knowles. 8°
Alfo, a MS. containing Calculations of
the Weight of the different Velocities
of Wind. 3°
Obfervations on the Weaith and Force of
Nations. 12°
A MS. intituled, Lettre 4 M. Garampi,
Nonce Apoftolique a Vienne, fur
quelques Curiofités Phyfiologiques ;
written in Italian by the Chev. Rofa,
and tranflated into French by the Mar-
quis de Hauteforte. fol,
Confiderations on the State of Dover
Harbour. 4°
Obifervations and Experiments for invetti-
gating the Chemical Hiftory of the
Tepid Springs of Buxton, 2 vols. 8?
De Artificio Navigandi per Aerem, by
Prof. Lohmeier, of Rinteln, printed
in the Year 1676; together with a
German Tranflation, >
A Specimen of. the Afhes and Filaments
thrown up in the Summer of 1783,
by the fubterraneous Fires im Iceland,
Commentationes per Ann. 1782, vol. 5.
fe}
Effai de Trigonométrie Spherique, by
M. Trembley, junr. 8°
Biographia Britannica, vol. ITI. fol.
A Voyage to the Pacific Ocean, under-
taken by the Command of Fe Ma-
jefty, for making Difcoveries in the
Northern Hemifphere, performed un-
der the Direction of Captains Cooke,
Clerke, and Gore, in three Volumes,
Alfo, a Volume of Plates. fol.
Nouveaux Memoires de l’Académie Royale
pour 1781. ")
Logarithmifche, Trigonometrifche, und
andere Tafeln und Formula, 8°
Donors.
1784.
[ 506. J]
Denore.
June 17. John Howard, Efq. F.R.S,
July 1.
George Atwood, M. A.
F.R.S.
M. Aniffon.
Profeffors Piller and Mitter-
pacher.
Sig. Giov. Vivenzio.
Thomas F, Hill, Efq.
William Cullen, M.D.F.R.S.
M., Roland de la Platritre,
Anonymous Author.
Baron Cl. Alftroemer and
John Alftroemer, Efq.
FRS.
The State of the Prifons in Enel:
Wales, with an Account of fome Fo- et
Titles.
reign Prifons and Hofpitals, 3d Edit. :
An Analyfis of a Courfe of Lectures on
the Principles of Natural Philofophy,
$°
A Treatife on the Re&ilinear Motion and
Rotation of Bodies. Ne? i
Defcription d’une Nouvelle Preffe exé-
cutée pour le fervice du Roy. 4°
Iter per Pofeganam Sclavoniz Provinciam.
4°
Tftoria e Teoria de’ Tremuoti, 3
Antient Erfe Poems, colleted among the
Scottifh Highlands. 8°
A new Edition of the Firft Lines of the
Practice of Phyfic, 4 vols.
L’Art de préparer et dimprimer les
Etoffes en Laines, fol.
L’Art du Fabricant de Velours de Co-
ton. fol.
L’Art du Fabricant d’Etoffes en Laines.
fol.
L’Art du Tourbier. ae
Lettres écrites de Suiffe, d’ Italie, de
Sicile, et de Malthe, 6 vols. 8°
A fhort Attempt to recommend the Study
of Botanical Analegy. rg?
A Silver Medal of the late Dr. Daniek
Solander, F. R. S.
TO THE
SEVEN TY-F OUR TH VOLUME
OF) Cone E
PHILOSOPHICAL TRANSACTIONS.
A»
CIDS. See Teft Liquor, Red Cabbage, Violets.
Air, experiments on, by Henry Cavendifh, Efq. p. t1g. Principal view iw
making thefe experiments, ibid. All animal and vegetable fubftances contain fixed
air, ibid. No reafon to think that any fixed air is produced by phlogiftication, p.
120. Nor by burning of fulphur or phofphorus, p. 121. Unfuccefsful attempts
to difcover what becomes of the air loit by phlogiftication, p. 123-126. Account
of two experiments of Mr. Warltire’s, related by Dr. Prieftley, p. 126. Table of
the refult, the bulk of the inflammable air being expreffed in decimals of the common
air, p. 127. Examination of the nature of the dew which lined the glafs globe, p.
128. Which is all pure water, p. 129. Examination of the nature of the matter
condenfed on firing a mixture of dephlogifticated and inflammable air, ibid. Phlo-
gifticated air appears to be nothing elfe than the nitrous acid united to phlogifton, p.
135. The great probability that dephlogifticated and phlogifticated air are difting fub-
ftances, as fuppofed by M. Lavoifier and Scheele, p. 141. Enquiry in what manner
nitrous and vitriolic acids act, in producing dephlogifticated air, p» 143. Different
manner in which the acid aéts in producing dephlogifticated air from red precipitate
and from nitre, p. 146. Vezetables feem to confift almoft intirely of fixed and phlo-
WiOLe LOKI Uuu giflicated
[ 508 j ae
gifticated air, p. 148. Manner in which Mr. Cavendith would explain molt oF the ‘,
phenomena of nature, on Mr. Lavoifier’s principle of entirely difcarding Loic anate :
&c. p. 150° Tes
' Air, Remaiks on Mr, Cavendifh’s experiments on air, in a letter from Richard Kirwan,
Efq. p. 154. Experiments felcfed from Dr. Prieftley, to prove that fixed air is fome-
how or other produced in phlogiftic proceffes, either by feparation or compofition,
ibid. Of the calcination of metals, p. 155—-161. Of the decompofition of nitrous
air by mixture with common air, p. 161—164. Of the diminution of common air
by the ele€tric fpark, p. 164. Of the diminution of common air by the amalgama-
tion of mercury and lead, p. 165. Of the diminution of refpirable air by come
buftion, p. 166—169.
— Anfwer to Mr. Kirwan’s Remarks upon the Experiments on Air, by Henry
Cavendifh, Efq. p. 170. Refult of an experiment of Mr. de Laffone’s, made with
the ilings of zinc, digefted in a cauftic fixed allsali, ibid. Remarks thereon, p.
171. See Metals, Experiments to determine if fixed air is generated by a mixture
of nitrous and common air, p. 172, 173- Curious experiment of Mr. Kirwan’s, p.
174. Obfervation on an experiment of Dr. Pri: ftley’s with a mixture of red precipi-
tate and iron filings, ibid. "The argument on this fubdject fummed up, p. 175. The
generation of fixed air not the general effect of phlogilticating air, p. 177.
-— Reply to Mr. Cavendifh’s Anfwer, by Richard Kirwan, Efq. p. 178. Anfwer to Mr.
Cavendifh’s remarks on Mr. Laffone’s experiment with filings of zinc digefted in acauttie
fixed alkali, ibid. Ditto to his obfervations on the calcination of lead, ibid. Extraét of
Dr. Priettley’s letter, concerning the black powder which he formed out of an amalgam
of mercury and lead, p. 179. Fixed air, produced by the diftillation of red precipi-
tate and the filings of iron, canner be attributed to the decompofition of the plum-
bago contained in the iron, ibid. Mr. Cavendifh’s experiment of the nitrous fele-
nite’s abforbing fixed air, juft, and agreeable to Mr. Kirwan’s, p. 180. The perma-
nence of a mixture of nitrous and common air, made over mercury, not to beattri- .
buted to common vapour, ibid.
—— Thoughts on the conftituent Parts of Water and of dephlogifticated Air, with
~ an Account of fome Experiments on that Subject, in a letter from Mr. James Watt,
Engineer, p. 329+ The author’s reafons for delaying the publication of his fenti-
ments on this fubje&, p. 330. Obfervartions on the conftituent parts of inflammable
air, ibid. Effects of mixing together certain proportions of pure dry dephlogifti-
cated air and of pure dry inflammable air, in a ftrong glafs veffel, clofely thut, fet on
fire by the electric fpark, p. 331, 332- See Cavendi/>, Humor, or dephlogifticated .
water, has a more powerful attra¢tion for phlogifton than it has for latent heat, but :
cannot unite with it, at leaft not to the point of faturation, or to the total expulfion j
of the heat, unlefs firft made red-hot, or nearly fo, p. 334. A mixture of dephlo- ee
gifticated and inflammable air will remain for years in clofe veffels, in the common wi
heat of the atmofphere, without any change, and be as capable of deflagration as
Pp ; y Ss P g
when
[ 509 ]
when firft fhut up, ibid. Accounted for by Dr. Prieflley, ibid. The author aban-
dons the opinion that air is a modification of water, p. 335- In every cafe, wherein
dephlogifticated air has been produced, fubftances have been employed, fome of
whofe conftituent parts have a ftrong attraction for phlogifton, p. 336. Phaenomena
obferved from combinations of the nitrous acids with earths from which the deph'o-
gifticated air is obtained with lefs heat than from nitre itfelf, p. 338. Experiment to
examine whether the phlogifton was furnifhed by the earths, p. 339. Ditto to deter-
mine whether any part of the acid entered into the compofition of the air, ibid.
Ditto to determine the quantity of acid in the receiving water and in the fublimate,
p- 341. Ditto of the diftillation of dephlogifticated air from cubic nitre in a giafs
veffel, p. 342. If any of the acid of the nitre enters into the compofition of the
dephlogifticated air, it is avery fmall part; and it rather feems that the acid, or part
of it, unites itfelf fo firmly to the phlogiiton as to lofe its attra€tion for water, p.
344. Any acid, which can beara red heat, may perhaps concur in the production
of dephlogifticated air, ibid. Dephlogiiticated air obtained from the pure calces of
metals may be attributed to the calces themfelves, ibid. General reafoning on the
fubject, p. 346. Mr. Scheele’s hypothefis, p. 347. The heat extricated during the
combuttion cf inflammable and dephlogifticated air is much greater than it appears
to be, p. 348. By an experiment of Dr. Prieitley’s it appears, that nitre can pro-
duce one-half of its weight of dephlogiiticated air, p. 349. Dephlogifticated air, in
uniting to the phlogifton of fulphur, produces as much heat as in uniting with the
phlogifton of phofphorous, ibid. Dephlogifticated air unites completely with
about twice its bulk of the inflammable air from metals, ibid) Experiments by Meff.
Lavoifier and De la Place, p. 350. The union of phlogiflon, in different propor-
tions with dephlogifticated air, does not extricate different quantities of heat, ibid.
Charcoal, according to Dr. Prieftley, when freed from fixed air, and other air which
it imbibes from the atmofphere, is almoft wholly convertible into phlogifton, p.
351. Enquiry whether all the heat let loofe in thefe experiments was contained in
the dephlogifticated air, p. 352. Not to be anfwered without many new experi-
ments, p. 353.
Air, Sequel to the foregoing Paper, in a fubfequent letter from the fame, p. 354-
Cautions neceffary to thofe who may chufe to repeat the experiment m entioned in the
foregoing paper, ibid.—356. Some circumftances pointed out which may caufe
“variations in the refults, p. 356.
Alchorne, Mr. Stanefby. See Gold.
Algol, Obfervation of the Variation of Light in that Star, in a letter from Sir Henry
C. Englefield, Bart. p.1. The laft vifible period when Mr. Aubert and Sir Henry
obferved it, ibid. Refult of feveral obfervaticns made at different times from mid-
night to 2h. p. 2. The diminution of Algol fully confirmed, and the accuracy of
Mr. Goodricke’s period afcertained, ibid. Sce Algol cn the index in the laf? volume.
Uw uy2 Algol,
| {- sao J 7
Alg:!, Obf-rvations on the Obfcuration of that Star, by Palitch, a farmer, in a letter
from the Count de Brubl, p. 4. Times of the greateft obfcuration, and of the
greateft diminution of the flar’s light, ibid.
Furiher Obfervations upon, by the fame, p. 5. eo)
——- on the Periods of the Changes of Light in that Star, in a Letter from John
Goodricke, Efg. p. 257. Method purfued to determine, with greater precifion, the
periodical return of thofe changes, ibid. With an explanatory table, p. 288.
Different obfervers may differ in the duration of the variation, and why, ibid.
Flamftead has marked this ftar of different magnitudes, at different times, p. 28Q-
Short abitract of Mr. Goodricke’s late obfervations on Algol, when its leaft magni-
tude was accurately determined, p. 2g0—2y2.-
Alhalies. See Te? Liquor.
Anarrhichas Lupus, A Defcription of the Teeth of that Fifh, and of thofe of the
Chetodon Nigricans of the fame Author; to which is added an Attempt to prove
that the Teeth of cartilavinous Fifhes are perpetually renewed, by Mr. William
Andre, furgeon, p. 274. The fame variety prevails in the internal ftruéture of fifhes
as in the external form, ibid. Jaws of the wolf-fith defcribed, p. 275, 276. And its
teeth, p. 277. Theteeth of the Chetodon nigricans deferibed>p. 278. Which fith
feems to be mifplaced in Linnzus’s Sy ftema Natura, ib. Of the teethof cartilaginous
;
.
fithes, p. 279. See Shark. Their pofterior teeth always found in a foft, membranous
{tate, and but imperfectly formed, p. 231. Explanaticn of the plates, p. 282.
Atkins, Mr. John. See Meteorological Fournal,
Aubert, Mr. See Algol.
Alexander, Efg. See Derecrs.
Aurora Borealis, curious account of, by Profeffor Gmelin, p. 228. Rufhing foife
attending that phenomenon, ibid. 229.
B.
Bark-Tree, Account of a new Species of, found in the ifland of St. Lucia, by Mr.
George Davidfon, p. 452. Botanic character of, by Sir Jofeph Banks, p. 453. Is
undoubtedly a fpecies of the cinchona, ibid. Extraét of a letter from Mr. George
Davidfon, dated at St. Lucia, July 15, 1783, giving an account of its difcovery by
Mr. Alexander Anderfon, and its medicinal qualities, p. 454. Mr. Davidfon’s
account of it, p. 455. Explanation of the plates, p. 456.
Barker, Thomas, Efq. See Rain.
Barometer. See Rain.
Bergman, Profeffor, his computation of the average height of the northern lights, p.
227. See Terra Ponderofa.
Blagden, Charles, M.D. See Afereors.
C. Cavallo,
[sae J
C.
Cavallo, Mr. Tiberius. See Mercors.
Cavendio, Henry, Efg. See dir.. Was the firft who difcovered that the combuftion of
dephlogifticated and inflammable air produced moifture on the fides of the glafs vefftel
| in which they were fired, p. 332.
Chatodon Nigricans. See Anarrhichas ae.
Cinchona. See Bark-Tree.
Clap, Profeflor. See Meteors.
Clufter of Stars. See Conftruction of the Heavens.
Cole, Mr. See King’s Wells.
Coma Berenices. See Conffruction of the Heavens.
Comet, extract of a letter from Edward Pigott, Efq. containing the difcovery of one, p.
20. Confufed notions of the ancients, and fome moderns, concerning them, p.
20Ie
Obfervations on that of 1783, p. 460. Table of obfervations from Nov. 19,
to 26. and Dec. 23. ibid. Night-glafs ufed on this occafion defcribed, p. 461.
Its different appearances at different times, p. 461. Table of obfervations made by
Mr. John Goodricke, p. 462. Difcovered on Nov. 26. by M. de Mechain, ibid.
Confirudiion of the Heavens, Account of fome Obfervations tending to inveftigate, by
William Herfchel, Efgs p. 437. Conftruction of his lately completed telefcope,
ibid. Reafons for confidering the heavens as an expanded firmament of three dimen-
fions, p. 438. Effect of applying the telefcope toa part of the Via Lactea, ibid.
Method of eftimating the number of the ftars feen, p. 439. Examination of the
nebulz and clufters of ftars lately given in the Connoiflance des Temps for 1783 and
1784, p- 439. Comparifon of different obfervations of Meff. Meffier and Mechain,
with thofe of Mr. Herfchel, p. 441. Four hundred and fixty-fix new nebule and
clufters of ftars difcovered, p. 442. Nebulz and clufters of ftars are arranged into
ftrata, which feem to run on toa great length, ibid. Double and treble nebula, with
others of various fhapes and lights, obferved, ibid. p. 443. Gaging the heavens
explained, with its ufe, p. 445. Table extracted from the gages, by which it
appears, that the number of ftars increafes very faft on approaching the milky way,
p: 446. Conjectures concerning the motion of the folar fyitem, if the fun be placed
in the great fidereal ftratum of the milky way, ibid. Circumftances attending the
detecting of nebula, p. 448. Nebula of Cancer, part of a firatum, its fituation, pe
449. Conjectures concerning the extent of the ftratum of Coma Berenices,
ibid.
Cooper, William, D. D. See Meteors.
Copley, Sit Godfrey, his medals adjudged, p. viii.
Cullum, Sir John, Bart. See Fro/.
D, Davidjon,
ae
Io
Davidfon, Mr. George, See Bark-Tree.
De Galvez, M.le Comte. See Machiees Aéroftatiques.
De la Place. See Air, Thermometers. Ni |
Double and Triple Stars. See Herfchel. gk
E, | |
Edgworth, Richard Lovell, Efq. See Meteors.
Electricity, its near connexion and analogy with meteors, p. 224—232.
Englefield, Sir Henry C. Bart. See Algol.
Evaporation, that it produces cold, and even ice, has been decidedly eftablifhed by expe-
riments, p. 383.
Expanfioa. See Thermometer.
F,
Falling Stars, obfervations made on them by diiferent perfons at diftant ftations, much te
be withed for, p. 224.
Fire-ball, a remarkable one feen all over England, p. 286. See Meteors.
Fifbes. See Anarrichas Lupus.
Fixed Air, is now known to be an acid, and capable of being abforbed by feveral fub-
ftlances, p. 154.
Fixed Stars, on the Means of difcovering the Diltance, Magnitude, &c. of the Fixed
Stars, in confequence of the Diminution of the Velocity of their Light, in cafe fuch a
Diminution fhould be found to take place in any of them, and fuch other Data
fhould be procured from Obfervations, as would be farther neceffary for that Purpofe,
by the rev. John Michell, B. D. p. 35. Rules relative to the above fubjec&t from Sir
Ifaac Newton, with corollaries deduced therefrom, p. 36—57. ‘The figure, tab. JIL,
explained, p. 38. et feq. The well-defined round difk of the fixed ftars, mentioned
by Mr. Herfchel, is not a real difk, but only an optical appearance, p. 45. See Air.
On a Method of defcribing the relative Pofitions and Magnitudes of the
Fixed Stars; together with fome Aftronomical Obfervations, by the rev. Francis
Wollafton, LL.B. p. 181. Reafon for fuppofing there may have been feveral changes
among the fixed ftars, which we little fafpeét, ibid. Plan propofed to aftronomers for
producing a Celettial Alas, far beyond any thing that has ever yet appeared, ibid. A
method of difcovering variations, which when difcovered, or only furmifed, fhould
be configned immediately to a more ftrict inveltigation, p. 182. Manner of pre-
paring a telefcope for this purpofe, ibid. Card more fully to explain this method, ibid ,
See tab. V. fig. 1. Different ftars muaft fucceffively be made central when any fufpi-
cion
a pat re
: 1M
Cais
cion of a miftake arifes, p. 185. Beftkind of illuminator defcribed, ibid. Hints to
aftronomers, if a general plan be fet on foot, 187—18g9. Aftronomical obfervations
made at Chiflehurft in Kent, 190—200. On the eclipfe of the moon, July 50,
1776, p. 190. Eclipfe of the fun, June 24, 1778, p. 192. Eclipfe of the
moon, Nov. 23, 1779, p: 193. Eclipfe of the fun, O&. 16, 1781, p. 194. Eclipfe
of the moon, Sept. 10, 1783, ibid. Tranfit of mercury over the fun’s dik,
Nov. 12, 1782, p- 197. Occultation of Saturn by the moon, February 18, U7
ibid. Occultations of ftars by the moon, p.198. Eclipfes of Jupiter’s fatellites, p.
199. Explanation of the figures in tab. V. p. 200.
Flamfiead. See Algol,
Froff, an Account of a remarkable one on the 23d of June, 1783. Ina letter from the
rev. Sir John Cullum, Bart. p. 416. State of the air when the froft happened, ibid.
Remarkable eifeéts of this unfeafonable froft, ibid. p. 417. State of the weather
previous toit, p. 417.
G.
Gaging the heavens. See Confiruction of the Heavens.
Gold, Experiments on mixing Gold with Tin. In a Letter from Mr. Stanefby Alchorne,
of his Majefty’s Mint, p. 463. The general opinion of metallurgifts concerning
the mixture of gold with tin, as exprefled by Dr. Lewis, ibid. Experiments, thew-
ing that tin, in fmall quantities at leaft, may be added to gold, without producing
any other effect than what might eafily be conceived, 4 priori, from the different tex-
ture of the two metals, p. 464—467. Experiments 1, 2, 3, 4, 5. with different
proportions of pure tin and refined gold, p. 464, 465. Experiment 6. to determine
how far the fumes of tin, brought into contact with gold, would do more than mix-
ing the metal in fubftance, p. 465. Conclufions from the foregoing experiments, p.
466. Experiment 7. to difcover whether the two metals might be more intimately
combined, and the mafs rendered brittle by additional heat, ibid. Experiments &.
and g. with mixtures of gold and tin, from exp. 2. and 4. and an ounce of copper
added to each, p. 467. Experiments 10. and 11. with equal parts of the laft mix-
ture and of the bar from exp. 3. ibid. Experiment 12. to examine whether the
adding of tin to gold, already alloyed, would caufe any difference, ibid. General
conclufions, p. 468.
Goodricke, John, Efg. See Algcl. Has one of Sir Godfrey Copley’s medals adjudged
to him, p. vii. |
Hi.
Halley, Dr. See Meteors.
Hala, or Rainbow, ncommon one, pe ge
Farwicke
¥e Lee
[ sta]
Harwich, See King’s Wells.
Heat. See dir.
Herfehel, Mr. his wonderful progrefs in the difcovery of double, triple, &e, ae perm.
36. The far greater part of which are doubilefs fyftems of ftars fo near each other
as probably to be fenfibly affected by their mutual gravitation, ibid. See Fixed Starsy
Mars, Conffruction of ibe Heavens.
Hoar-froft, why found upon grais, trees, &c. when there is ne appearance of lee upon —
water, andthe thermometer is above the freezing point, p. 380,
Humfrys, Lieut. See King’s Wells.
Humor, See Air.
Humphreys, Mr. of Norwich. See New Plani,
Hutchins, Thomas, Efq. Has one of Sir Godfrey Copley’s medals affigned to him,
pe Viil.
Hutten, Charles, LL. D. See Quadrant.
I,
Jee. See Thermometer, Hoar-frof, Evaporation.
K. .
King’s Wells, Defcription of thofe at Sheernefs, Landguard-Fort, and Harwich, by
Sir Thomas Hyde Page, Knt. p. 6. Some circumftances refpecting the garrifons of
Sheernefs, &c. p. 7. Sir Thomas directed to confider how to remedy the want of
water at thofe places, ibid. Situation in which he found Sheernefs, p. 8. Ditto of
Landguard-Fort, ibid. Ditto of Harwich and its neighbourhood, p. g- Operations
at the well in Fort Townfhend, Sheernefs, p. 1o—15. Which were much forwarded
by the affiduity of Mr. Cole, Lieut. Humfrys, and Mr. Marthall, ibid. Time of
beginning and finifhing the work, p.11. Method of lining the well with wood, to
prevent the mud’s falling on the workmen from above, ibid. and the filtration of
the falt-water through the fand, p. 12. Manner of ftopping out the. falt-water
entirely, and fecuring the foundation of the works, p. 13. A piece of a tree dif-
covered 300 feet from the top of the well, p. 14. The bottom of the well blown
up, and the water rifes forty feet in the bottom of the well, p. 14. Quality of the
water ibid. Operations at Landguard-Fort when begun and finifhed, p. 15. Im-
probability of finding frefh-water there, which is difcovered by accident, ibid. And
isfound in great quantities, but at the depth of low-water-mark becomes entirely
falt, p. 16. Means ufed to remove this impediment, ibid. Conjecture concerning
the caufe of the frefh-water, p. 17. Operations at Harwich when begun and finithed,
p- 18. But little water there, and bad, ibid. A new well funk, and a plentiful
fupply of frefh-water procured, p.1g. Explanation of the plates, ibid.
Kirwan, Richard, Efq. See dir.
3 : L. Landerbech,
- —* oe
eM
¥
Ee sto]
Ram a Os
Zonder beck, Mr, See. Linas Guibas
Landguard-Fort. See King’s Wells.
Lapis bufonites, how.originated, p. 277.
Lavoifier, M. See Air, Thermometer.
Lewis, Dr. See Gold.
Light, has a remarkable power in enabling. one body to abforb phlogitton from another,
~ p» 147. Probability that the ufe of light in promoting the growth of plants, and the
produétion of dephlogifiicated air from them, is its enabling them to abforb phlogifton
from the water, p. 149.
Lineas curvas, Methodus Inveniendi, ex proprietatibus Variationis Curvature, aiGare
Nicolao Landerbeck, Mathef. Profeff. in Acad. Upfalienfi adjunéto, Pars fecunda,
(See Index to laf? volume) p. 477. Theorema I. ibid. Cor. 1. p.478. Cor. 2.
ibid. Schol. 1, ibid. Schol. z. ibid. Exempl. 1. p. 480. Exempl. 2. ibid.
‘Theorema Il, p. 481. -Cor. 1. ibid. Cor. 2. p. 482. Cor. 3. ibid. Schol. 1.
ibid. Schol. 2. ibid) Exempl. 1. p. 484. Exempl. 2. p. 485. Theorema III.
ibid. Cor. x. ibid. Cor. 2. p. 486. Cor. 3. ibid. Schol. 1. ibid. Schol. 2. ibid.
. Exempl. 1. p. 488. Exempl. 2. ibid. 'Theorema IV. ibid. Cor. p. 489. Schol.
ibid. Exempl.1.p. 490. Exempl. 2. ibid, Exempl. 3. ibid. Exempl. 4. p. 4916
| Theorema V. ibid. Cor. ibid. Schol. ibid. Exempl. 1. p. 492. Exempl. 2. ibid.
Exempl. 3. p. 463. Exempl. 4. ibid. Theorema VI. ibid. Cor. p. 494. Schol. ibid.
Exempl.°1. ibid. Exempl. 2. ibid. Exempl. 3. p. 495. Theorema VII. ibid.
Cor. ibid, Schol. ibid. Exempl. 1. p. 496. Exempl. 2. ibid. Exempl. 3. ibid.
Theorema VIII. ibid. Cor. p. 497. Schol. ibid. Exempl. 1. ibid, Exempl. 2.
Therema IX. p. 498, Cor. ibid, Schol. ibid, Exempl. 1. p. 499. Exemp. 2.
P» 500.
Litmus, Refults of its ‘sei mixed with acids, alkalies, &c. p. 419. Fatt which feems
tocall in queftion its being always a teft of the exact point of faturation of acids and |
alkalies, p. 420. See Red Cabbage. asean
Local Heat, Experiments to inveltigate the Variation of, by James Six, Efg. p. 428.
Thermometers made ufe of in thefe experiments, and manner of placing them, in
September, 1783, p. 428. Obfervation on the refult of this experiment, p. 429.
Manner of placing them on Dec. 19, 1783; ibid. Refult of the experiment, ibid.
Different difpofitions of the atmofphere at the time of making thofe obfervations,
Pp» 430: Warious flate of the weather in Sentember, December, and the
-beginning of January, withvits c#eGts on the inftrunients, p. 430—432. Deferip-
tion of the valley in which Canterbury cathedral flands, near which thefe
experiments were made, p. 432» Difcoveries:which may pofibly refule from
experiments of this kind, p, 433. ‘Table 1. of the greateit daily variation of
Vou, LXXIY. KX x heat
a i a eer
Sy
£316]
heat and cold in the atmofphere, from the 4th to the 24th of September, 1483,
taken from three different flations, and compared together, p. 435. Table II. af
the greateft daily variation of heat and cold, from the 20th of wane nil
the 8th of January, 1784, &. p. 436 iy
Lycoperdon. See New Plant. a Soh oAaer ian
Machines Aéroftatiques, fur un moyen de donner la Direction aux, par M. Le Comte De
Galvez, p. 469.
Magellan, M. de. See Comet,
Mann, Abbé. See Meteors.
Mars, on the remarkable Appearances at the Polar Regions of that Planet, the Inclina-
tion of its Axis, the Pofition of its Poles, and its {pheroidical Figure; with a few
Hints relating to its real Diameter and its Atmofphere, by William Herfchel, Efg.
p- 233- Various lucid fpots obferved on the planet Mars, with remarks thereon, p.
235—246. Of the direction or nodes of the axis of Mars, its inclination to the
ecliptic, and the angle of that planet’s equator with its own orbit, p. 247. et feq.
Of the fpheroidical figure of Mars, p. 261. Obfervations relating to the polar flat-
tening of Mars, p. 262. Refult of thecontents of this paper, p. 273.
Marfball, Mr. See King’s Well.
Martineau, Mr. Philip Meadows. See Ovarium.
Mercure, Obfervations du Paffage de Mercure fur le Difque du Soleil le 12 Novembre,
1782, faites 4 l’Obfervatoire Royal de Paris, avec des réflections fur un effet qui fe
fait fentir des ces mémes Obfervations femblable 4 celui d’une Refraction dans l’At-
mofphere de Mercure, par Johann Wilhelm Wallot, Membre de l’Academie Elec-
torale des Sciences et Belles Lettres de Manheim, &c. p. 312. Reéfultats du caleul
des obfervations précédentes felon leurs différentes combinaifons, p. 314. Table des
refultats du calcul des obfervations de contacts et du centre de Mercure, p. 319.
Conclufion, p. 327.
Mercurius Calcinatus, and red precipitate nearly the fame thing, p. 144.
Mechain. See Comet, Conftruétion of the Heavens.
Meffier. See Confirudtion of the Heavens.
Metals, two methods of calcining, p. 172.
Meteorological Fournal for the Year 1782, kept at Minehead in Somerfetfhire, by Mr.
John Atkins, p. 58. Defcription of the inftruments ufed, and explanation of the
tables, p. $9. Journal for January, p. 60>—63. For February, p. 64—67. For
March, p. 68—71. For April, p. 72—75. For May, p. 76—79. For June, p.
8o—-83. For July, p. 84—87. For Auguft, p. 88—g1. For September, p.
92-95. For O&ober, p. 96—99. For November, p. 100—103. For December,
Pp: 104—107.
Meteors,
i in Mes. sa " + a We ee wh hs aa a
& As ‘ig ; pee Sch i
ae I
Sercors, Defeription of one obferved Auguft 18, 1783, by Mr. Tiberius Cavallo, p.
108. State of the weather, and fituation of the meteor, ibid. Its courfe, direction,
and duration, p. 10g. Acquires a tail, parts into feveral {mall bodies with tails, and.
difappears, p. 110. A rumbling noife heard after its difappearance, ibid. Con-
jetural calculation of its diftance, altitude, courfe, &c. -p. 111.
w—— Account of thofe of the 18th of Auguft and 4th of Oétober, 1783, by
Alexander Aubert, Efq. p. 112. Method he tock to be able to give a perfect account
of it, ibid. Time of its appearance, and ftate of the heavens, p. 112. Manner of
the firft appearance of that of Auguft 18, and its diiferent changes, p. rr3. Its
magnitude, ibid. Its duration, and length of its courfe, p. 114. Its fuppofed alti-
tude, ibid. Appearance of that of O&. 4, ibid. Its courfe and variety of
appearances, ibid. p. 115. Time of appearance, ibid.
Obfervations on a remarkable one feen on the 18th of Auguft, 1783, by Wil-
liam Cooper, D. D. Archdeacon of York, p. 116. State of the weather and atmo-
fphere, ibid. Sulphureous vapours obferved previous to the appearance of the
meteor, ibid. Its courfe, ibid. And altitude, p. 117. Its divifion into feveral balls
of fire, followed by two loud explofions, ibid.
Account of that of the 18th of Auguft, 1783, in a letter from Richard Lovell
Edgeworth, Efq. p.118. Its time of appearance, ibid. Its fize and duration, ibid.
Was twice eclipfed, ibid.
=—— An Account of fome late Fiery Meteors, with Obfervations, in a Letter from
Charles Blagden, M. D. Sec. R. S. Phyfician to the Army, p. 201. Different names of
thefe meteors among the ancients, ib. See Comets. General appearance of thatof the
- 18thof Augutt, 1783, p. 202. Its path defcribed, p. 203. Different fhapes in which
it appeared owing tothe different points of view in which it was feen, p. 205. Was
not always of the fame magnitude and figure, ibid. Different fhapes of meteors
accounted for, p. 206. Burft, and feparated into feveral {mall bodies, ibid. Seems
to have undergone other explofions before it left our ifland, and alfo upon the conti-
nent, p. 207. The extin@tion of meteors by fuch explofions doubtful, ibid. The
‘ great change in this correfponded with the period of its deviation from its courfe,
with remarks thereon, p. 207. Obfervations on the light and colours of thefe meteors,
ibid. Time of its greateft lufire, p. 208. And on its height, with the method of
taking it, p. 209. Eftimations of the altitude of that of Auguft 18, by different
perfons at different fituations, p. 211—213. Obfervations on the noifes attending and
following thefe meteors, which, by fhaking doors, éc, is frequently miftaken for aw
earthquake, p. 215. Its enormous ‘bulk, p. 216. Jis duration differently ftatedy
and why, ibid. The periods of its duration are moftly ‘by guefs, and why, p.°217-
its aftonifhing velocity, p. 218. Account.of the fire-ball which appeared OC. 4, p.
zig. Difficulty of accurately determining the direction of its courfe, ibid. Dif
ferent opinions about it, p. 220. Iss héighty ibid.) [ts fae, ibid, Its duration and
r
Renee velocitr,
— Ps ae
oh) a a a i & % re HRY ATES Pre US ie RA ury t ,
Re ana ‘ Yah
‘
: om i dae |
velocity, p. 221. A fimilar one appeared the fame day, ibid.’ Meteors whiélt
defcribe short courfes unfavourable for calculating the velocity, but advantageous for
determining the height, ibid. Refleétions om the cavfes' of meteors, with different
opinions concerning them, p. 222. Dr, Halley’s hypothefis, ibid. Opinion of Pro-
feflor Clap, of Yale College, New England, p. 223. Strong objection to his hypo-
thefis, ibid. See Falling Stars, EleGricity, Mr. Robinfon’s account of one feen at
Hinckley in Leicefterfhire, O28. 26, 1766, p. 225. Curious optical effect te
by the Abbé Mann, p. 226. See Aurora Borealis,
Meteors, an Account of that of Auguft 18, 1783, made on Hwie a near Wak,
in a letter from Nathaniel Pigott, Efq. p. 457. Its firft appearanee, p. 457. Fig.
1. tab. XX. explained, ibid. Its motion, p. 458. Fig. 2. explained, ibid. Its
apparent diameter and altitude, ibid, Duration, ibid. Diftance and altitude at its
extinction, p. 459.
Michell, rev. John, B.D. See Fixed Stars,
Milky Way. See Via Ladtea.
N,
lebula. See Confirudtion of the Heavens.
New Plant, an Account of one, of the Order of Fungi, by Thomas Woodward, Efq.
p- 423. Generical defcription, ibid. Manner of its firft appearance, which renders
it diilicult to detect ic in its earlieft ftate, ibid. Its rapid progrefs to its perfedt. ftate, p.
424. Firit difcovered by Mrs Humphreys of Norwich, ibid. Is not the Agaricus
procerus, p. 426. Approaches nearly the genus Lycoperdon, p. 426. Plants which
have all fome affinity with the fructification of this, plant, ibid. Comes frequently te
a ftate of perfection before it reaches the furlace, ps 427.
O.
Ovarium, An extraordinary Cafe of a Dropfy of, by Mr. Philip Meadows Martineau,
Surgeon tothe Norfolk and the Norwich Hofpital, p. 471. Age and condition of the
patient at the beginning of the diforder, ibid. Her deplorable appearance afterwards,
ibid. Swelled to an amazing fize, p. 472. Continuance of her diforder, ibid.
Number of times fhe was tapped, and quantitity of water drawn off at each time,
ibid. p» 474. Comparifon of her cafe with that of Lady Page, related by Dr. Mead, p.
474+ Seat of the diforder, and fate of the vifcera, on diffection, p. 475. Reflec-
tions on the whole, p. 476.
P,
Page, Sir Thomas Hyde, Kant. See King’s Welles :
Palais Pave, what, p. 277.
Palitch,
{ 3% J
Palitch. See Algol.
Phiogifton, See Air, Light. f
Phofphorus. See Air.
Pigott, Edward, Efq. See Comet.
Nathaniel, Efg. See Meteors.
Plumbago. “See Air.
Prefents, Lift of, p. Sore
Pricfley, Dr. See dir.
Q
Quadrant, Project for a new Divifion of, by Charles Hutton, LL.D. p. 21. Project
-for conftructing fines, tangents, fecants, &c. to equal parts of the radius, p. 22.
Particulars relative to this project explained, p. 2 yesh
R.
Rain, Abfira& of a Regifter of the Barometer, Thermometer, and Rain, at Lyndon,
in Rutland, 1783, by Thomas Barker, Efg. p. 283. State of the weather from the
beginning to the end of that ae p: a.
Rainbow. See Halo.
Red Cabbage, furnifhes the beft teft, and in its frefh ftate hath more fenfibility both to
acids and alkalies than litmus, p.420. Diiferent methods of extracting the colouring
matter, p. 420—422. And of preferving its virtues’ whilft kept in a ligpid ftate, p.
421. See Violets.
Red Precipitate. See Mercurius calcinatuss.
Robinfon, Mr. See Meteors.
Scheele, M. See Air.
Series. On the Summation of thofe, whofe general Term is a determinate Function
of x the Diftance of the Firft Term of the Series, by Edward Waring, M. D. Lucas
fian Profeffor of the Mathematics at Cambridge, p.385—415.
Shark, miftake of fome naturalifts concerning that fifh, p. 2795
Sheernefs, See King’s Wells.
Six, James, Elfqg. See Local Heat,
Solar Syfem. See Conftrudtion of the Heavenss
Sulphur. See Air.
Sun. See Couftruction of the Heavens
T. Teeth.
EMA Pe Lot 4
ta beet
Teeth, See Anarrbichas Luputs
‘ ‘ So Set yen te
T. a ih Sea
eT ‘eqn >
‘yXe Sear
Telefeope. See Conftruction of the Heavens.
Terra Ponderofa, Experiments and Obfervations on, by William Withering, M. D. Pe
293- Terra ponderofa aérata, its conftituent parts, ibid. Profeffor Bergman’s con-
jecture concerning it, p. 294. Its more obvious properties, ibid. Experiments on,
p- 295—297- Conclufions therefrom, p. 298. And obfervations thereon, p-
298—302.
%eft Liquor, on a new Method of preparing one to fhew the Prefence of Acids and
Alkalies in chemical Mixtures; by Mr. James Watt, Engineer, p. 419. Syrop of
‘violets was formerly the principal tef{ of the point of faturation of mixtures of acids
and alkalies, ibid. The infufion of tournefol, or of a preparation called litmus fince
fubftituted in its ftead, ibid. See Litmus, Red Cabbage, Violets.
Thermometer, See Rain. An Attempt to compare and connect the Thermometer fo
{trong Fire, defcribedin Vol. LX XII. of the Philofophical TranfaGtions, with the com-
mon Mercurial ones, by Mr. Jofiah Wedgwood, F. R.S. Potter to Her Majefty, p.
358. The defign of the experiments recounted in this paper explained, ibid. p. 359.
The three firft figures of tab. XIX. explained, p. 359. Means employed for obtaining
an intermediate thermometer, ibid. ‘The fpecies of gage ufed on this occafion ex-
plained by a reprefentation, p. 360. Caution to be obferved in meafuring the expane
fion of bodies, p. 361. Effential requifites of the matter proper for the gage, p.
362- ‘Tobacco-pipe clay and charcoal why preferred in making it, ibid. Method
of afcertaining a fixed point on the fcale for the divifions to be counted from, p. 363.
Method of taking the boiling heat of water, p. 364. And that of Mercury, p. 365.
Fig. 4. explained, ibid. Ditticulty of obtaining the higher degrees of heat, with
Mr. Wedywood’s thermometer, and his method of performing it, p. 366. Compa-
rative degrees of the different thermomerers, p. 368. Table of a few principal points
that have been afcertained, to fhew their mutual relations or proportions to each
other, p. 370- Scales of the utmott’ limits of heat hitherto attained and meafured,
ibid. 371. Obfervations on Meff. Lavoifier and De la Place’s method of meafuring
heat by the quantity of ice which the heated body is capable of liquifying, p. 371-
Machine for determining the progrefs of liquifying ice, by expofing it to a warmer
atinofphere, p- 372. Experiment for afcertaining that ice, how cold foever it may
be, comes up to the freezing point through its whole mafs before it begins to liquify
on the furface, p. 373. Experiments to afcertaim the abforbing power of ice, ibid.
374. Apparatus (fig. 6, tab. XV.) for ufing ice in thefe experiments defcribed, p.
375- Refults of various experiments, p. 376—379- See Hoar-frof. The freezing
of water is attended with plentiful evaporation in a clofe as well as in an open veffel,
. p- 3816
fwg2t, 9
p.38te Remarkable cireumftances in the coating of ice (fee p. 377.) on the outfide
of the throat of the funnel, p. 382.
Tine See Gold.
Tourncfol. See Tet Liguore
V.
Via Lattea, or Milky Way. See Conftrudtion of the Heavens, Conjecture concerning it,
P- 442-447.
Violets, method of making a red infufion of, which forms a very fenfible teft to thew the
prefence of acids and alkalies in chemical mixtures, p. 422.
WwW.
Wallot, Johann Wilhelm. See Mercure.
Waring, Dr. Edward. See Series.
Warltire, Mre See dir.
Water. See Air.
Wait, Mr. See Air, Left Liquor.
Wedgwood, Mr. Jofiah. See Thermometer.
Withering, William, M.D. See Yerra Pondero/a.
Wollafton, rev. Francis, LL.B. See Fixed Stars.
Woodward, Thomas, Efq. See New Plant.
FROM THE PRESS OF J.
NICHOLS.
Page. Line. fas wh
4 478. 18. for brighter read lefs bright tt AF adel gals
x 290, ebyparhal sh .
‘ VOL, LXXIV. PART Ih o78 sa: ae
. fn i 289. 8. for the read thofe Sup spk seas
| Ahad 290. Il. dele rather a oie 308... .dAdol the BF
% on 291. 8. forthe readthefe — ARK 918 | ae ee BR aie. *
i 329. 7» for 1984 read 1783 va ws nalts Nee
ae 341. 23. for, firlt, read fixed bey eg ‘
ty y 342. 12, for than read that '
nae 345 1. after from infert their
Spl OS SF Sor V read K
Ne In plate XIV. fig. 2. the letter a fhould be inferted at the b ttor
oP, and the letter d top, of the dotted interval 193, i
G fame manner as the letters and d at the two extremes of
dotted intervals in fig. 3. ; +
In ‘plate XXI, fig. 2. at the lower angle of the diagram,
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