616 Mr. nairne’s Account of 
“ moifture that adheres to the infide of the barrel as 
“ well as other internal parts, upon letting in the air, is 
(( in the fame fucceeding trials worked together with the 
t{ oil, which foon renders it fo clammy as to obftruft 
“ the actions of the pump upon a fluid fo fubtil as the 
<( air when fo much expanded ; but in this cafe it feldom 
(< fails to a< 5 t upon the air in the receiver till it is ex- 
<c panded 500 times.” Thus far Mr. smeaton’s ac- 
count. 
The pump with which the chief of the following ex- 
periments were made, had the leather of its pifton foaked 
in oil and tallow (and oil in the barrel) and every pre- 
caution was taken that no water fhould get into the 
working parts of the pump, except what might arife in 
vapour from the fubftances which were under the 
receiver. 
EXPERIMENT 1. 
Having provided a pear-gage agreeable to Mr. smea- 
ton’s defcription, on which the fpace of a 4000th part 
of the whole capacity was two-tenths of an inch; this 
gage, together with a glafs cup which ferved as a ciftern 
to 
