[ 445 3 
Porce to be rightly a {Turned by the Procefs in the 
preceding Part 5 that is, fuppofing the Elafticity of 
the Fluid thence arifing to be at firft: 1000 times 
greater than that of common Air ; for then, by com- 
paring the Refult of thefe Computations with a great 
Number of different Experiments, it would appear 
whether that Force was rightly afligned $ and if nor, 
in what Degree it was to be corre&ed. 
Preparatory to this Computation, the Author 
affumes in his 7th Propofition thefe Two Principles : 
3 ft, That the A&ion of the Powder on the Bullet 
ceafes as Toon as the Bullet is got out of the Piece. 
2 dly t That all the Powder of the Charge is fired, 
and converted into an elafiic Fluid, before the Bullet 
is fenfibly moved from its Place. 
And in the annexed Scholium he has given the 
Arguments and Experiments which induced him to 
rely on thefe Poftulates, all which is neceffary at pre- 
fent to difeufs more at large. 
If the Force of Gunpowder was fuppofed capable 
of being determined with the fame Accuracy and 
Rigour, which takes place in Subjects purely Geome- 
trical, the Firft of thefe Poftulates would be doubt- 
Jefs erroneous, fince it cannot be queftioned but the 
Flame acts in fome Degree on the Bullet after it is 
out of the Piece. 
But it is well known, that in Experimental Sub- 
je&s no fuch Precifenefs is attainable 5 for thofe 
verfed in Experiments perpetually find, that either the 
unavoidable Irregularities of their Materials, or the 
Variation of fome unobferved. Circumftance, occa- 
fion very difcernible Differences in the Event of 
fimilar Trials. Thus the Experiments made ufe of 
for 
