-s GAGE. : 
was uniformly fifty-one i in three different trials; but t the 
pear-gage exhibited firft fixteen thoufand, in the fecond in- 
the receiver was place 
mixture a water and Spirit of wine, the barometer-gage in 
three tria degree of exhauftion equal to 
forty an : but the pear gage was unaccountably various 5 
in the firit’ the eeg 
in wate 
vents the pump from ‘exhaulting in foes confiderable degree. 
By two other experiments, in which water was ufed for 
foftening the leathers of the piftons of a common air-pump, 
we find that the higheft degree of rarefaction that could be 
procured was thirty-feven, according to the barometer-gage; 
and thirty-eight according to the pear gage. Mr. Nairne’s 
aft _ furnifhes a very extraordinary evidence of 
the e of vapour on the barometer -gage: havin a 
phial of ether under the receiver, in order to pro 
al co in m 
barometer-ga 
only fixteen ; hough the fame ae exhaufted ae four 
hundred times before the ether was put under the receiver. 
‘The degree } of cold produced by means of ether, in the ex- 
hautted receiver, was 48°, below o in Fahrenheit’s is or 
103 below 55°, which-was the temperature of the air in the 
room where the experiment was made. hil. Tranfaét. 
vol. pea part i. art. 32 & 
E of the Barometer, is a contri ee for eftimating the 
ng in oie of ae aed and fall of the mercury in the 
ell an tube. well known, ee ailft the mercury 
rifes in the me it finks i in the ele ern, an nde vice verfd 3 and, 
as the diftance between the divifions graduated on the an- 
nexed fcale and the furface of the mercury in the ciftern is 
hot truly fhewn by the numbers on the {cale, errors mutt 
happen in determining the precife es of the mercury. 
ne pigreel this i inconvenie nee, a line upon a a round 
» page 61 
rt 
eal place 
ee fro 
cork, is left to play eee on ile 
er and the cylinder works in a tae made in the 
other : from this conftruction it appears, that if thefe 
marks are at to coincide, by raifing or lowering the 
ferew which acts on the quickfilver, t then the ditions on 
the fcale will exprefs the true meafure of the diftance from 
‘the furface. 
_ Gace of the Condenfer, is a glafs tube of a particular con- 
firu€tion, adapted to the condenfing engine, and defign 
we fd : 
e fe, Plate XIV. peahera: ig. 5. be — glafs 
tube, about one-tenth o diameter, nat 
but hermetically fealed at c; D E a larger a hermeti- 
cally fealed at D, and containing at that end a quantity 
of mercury, which takes up two or three inches in length, 
- covers the open end of the fmaller tube ; the other end 
C, of the larger tube, is ftrongly cemented into the brafs 
elbow-piece OE» at C, not to be quite at 
right angles with O 0, but to incline a “Tittle down wards, that 
ment. Whilft air is injeéted into the condenfing glafs, a 
the large tube of e fam e, the a 
{maller tube, Ania has no agine ieee — the injeGted 
i ult be rarer 
e 
aad ae ance in it, 
to the condenfation of ie air in GB. In es fs 
reprefent three rings of {pringy wire, at fuch I oe as to 
fhew, by the motion of the mercury in the {mall tube, when 
the denfity of the air is ean tripled, or quadrupled ; 
ater the oe which a firit filled pag who le fmall tube, 
This is a 
ic 
outward diameter of the cylinder muft be about four inches, 
fo that the cylinder may eafily ftand within the ares) 
glafs on the plate, fupporting i _ bottom at B, fg. 6. 7 ere 
1s a hole at A of about 4 of an inch in diameter and 4 
inch deep, filled with mercur 
. eatin 
t ¢; en one ated seen bears upon its furface, 
a; two atmofpheres, if it be come to d; which places are 
marked by rings of {pringing at wire ; ata aaa &, about 
an inch of the ends of the tube are bent to a right angle, 
that the end 4 may go into the wood, whilft the end a ae 
under the furface of the mercury, where it is held by a cork, 
whilft air is injeCted into the condenfing glafs. Dee 
Exp. Phil. vol. ii. p. 394 | aa Ce 
Gace, Sea. See — 
Bucke. ialkrament contrived by Dr. Hales 
to fi he different we of cooln 
n efs 7 a efs of the 
fea, fe different ac n houfhold 
pail o bucket, with two heads. Thefe heads hee each a 
round “hole in the middle, about four inches in diameter, 
fixed to the upper part of the lower valve, and the other end. 
to the lower fide of the upper valve. So that as the bucket 
defcends with its finking weight into the fea, both the valves 
may open by the force of the water, which by that means- 
has a free paflage through the bucket. But when the_ 
ucket is — n UP, then beth the valves fhut by the force of 
the water upper part of the bucket ;. fo that the: 
cket is trav up full a the loweft ra water to which it. 
has defcen 
When the Laceees is drawn up, the mercurial thermometer 
xed in it is examined; but great care muft be taken to 
Spee the degree at wlich the mercury ftands, before the 
lower part of the thermometer is taken out of the water in 
the bucket, left it be affected by the different temperature. 
of the air. 
In order to keep the bucket in a right pofition, there are 
four cords fixed to it, ee ie about three feet below it ;- 
to which the finking wei 
The refult of feveral Sale with this gage was, that when: 
et 
cold increafed gradually in. 
proportion to the oat, tilt it ine to 3900. feet, viz. 
7. near. 
