[ 44 * ] 
for confirming the Laws of the Collifion of Bodies, 
have never been found abfolutely to coincide either 
with the Theory, or with each other. The fame is 
true of the Experiments on the Running and Spout- 
ing of Water and other Fluids, and of the Experi- 
ments made by Sir Ifaac Newton , for the Confirma- 
tion of his Theory of Refiftances ; in which, though 
they often differ from each other, and from that 
Theory by One-twentieth, One-tenth, and even 
fometimes One-fifth Part, yet thofe fmall Inequalities 
have never been urged as invalidating his Conclufions, 
fince, in Experiments of that Nature, it was rather to 
be wondered at, that the Difference between the 
different Trials was fo fmall. 
And if fome minute Irregularities are the neceffary 
Concomitants of all complicated Experiments, it may 
be well fuppofed, that the Aftion of fo furious a 
Power as that of fired Gunpowder, which viftbly 
agitates and diforders all Parts of the Apparatus made 
ufe of, cannot but be attended with fenfible Varia- 
tions ; and it in Fa£t appears, that in the Table of 
Experiments inferted in the 9th Propofition, the Ve- 
locities of Bullets fired from the fame Piece, charged 
with the fame Powder, and all Circumftances as near 
as poflible the fame, do yet differ from each other 
by One-fiftieth, One-fortieth, and fometimes more 
than One-thirtieth, of the Whole ; and yet the Author 
does not conceive, that thefe fmall Differences are 
any Exception to the Conclufivenefs of his Principles; 
but he prefumes, that had he pretended, without dif- 
clofing his Method, to have computed the Force of 
Powder, and the Velocities of Bullets, in different 
Circumftances, to a much lefs Degree of Accuracy 
than 
