634 Mr. nairne’s Account of 
tried, and one of my common double barreled table air- 
pumps under the fame eircumftances. The leather on 
the piftons of both was foaked in oil and tallow, and the 
receiver cemented down to each plate \ the pumps were 
both of them fireih oiled. 
^xp.xLiiii. A pieceof leather, weigh- 
ing ioo grains, as it came from 
£he leather- filers, was pu£ into 
the receiver of each pump, both 
pieces being cut from the fame 
fkin clofe by each other,, — 
exp. xliv* The fame piecesr of* lea- 
ther dried by the tire till they 
would lofe no more of their 
weight, — — 
The following experiments will fliew the effedt of 
water ufed in the barrels of pumps to make the piftons 
move air tight in them. 
I took the fame common air-pump ufed in the laft 
experiment, and having taken off the leathers leaked in 
oil and tallow from the piftons of this pump, and wiped 
the barrels as clean as poffible, I then put new leathers, 
which had been foaked in water, and new bladder valves ; 
the receiver was then cemented to the pump-plate as 
before. 
Pump on Mr. smea- 
ton’s principle. 
Degrees of exhauf- 
tion according to 
Common pump. 
Degrees of exhaus- 
tion according to 
Barom. 
gage. 
Pear- 
gage- 
Barom. 
gage. 
Pear- ’ 
gage- 
152 
100,000 
108 
22,000 
506 
520 
160 
165, 
3 
EXP. 
