Analyfts of the Air. 209 
preflesand confines this air in the Apples, 
muft be equal to the weight of 48 of our 
atmofpheres, when the Mercury in the Ba- 
rometer ftands at fair, that is 30 inches high* 
Now a cubick inch of Mercury weigh- 
ing 3580 grains, thirty cubick inches (which 
is equal to the weight of our atmofphere on 
an area of a cubick inch) will weigh 15 
pounds, 5 ounces, 215 grains 5 and 48 of 
them will weigh above 736 pounds $ which 
is therefore equal to the force with which an 
inch fquare of the furface of the Apple 
would comprefs the air, fuppofing there 
«wcre no other fubftance but air in the Ap- 
ple : And' if we take the furface of an Ap- 
ple at 16 fquare inches, then the whole 
force with which that furface would com- 
prefs the included air, would be 1 1 776 pounds* 
And fince aftion and re adion are equal, this 
would be the force, with which the air in 
the Apple would endeavour to expand it felf, 
1 if it were there in an elaftick and ftrongly 
compreffed ftaie: But fo great an expanfive 
; force in an Apple would certainly rend the 
fubftance of it with a ftrong explofion, ef- 
pecially when that force was increafed, by 
the vigorous influence of the Sun's warmth, 
P Wc 
