Upon Gun-powder, &c. 281 
Let us fee how this method of determining the velocities of 
bullets will anfwer. in praftice. 
In the 94th experiment the recoil, with 165 grains of pow- 
der, without a bullet, was 5,5 inches, and in the 95th experi- 
ment, with the fame charge, the recoil was 5,6 inches. The 
mean is 5,55 inches ; and the length of the rods by which the 
barrel was fufpended being 64 inches, the velocity of the recoil 
(= U) anfwering to 5,55 inches meafured upon the ribbon, is 
that of 1,1358 feet in a fecond. 
In five experiments, with the fame charge of powder, and a 
bullet weighing 580 grains, the recoil was as follows, viz * . 
20th experiment 
14,73 
2 1 ft 
14,2 
22d 
14,8 
23d 
4- 
v» 
CO 
24th 
14,68 
5)73,. ( = 1 4,6 inches at a mean. 
And the velocity of the recoil ( = V) anfwering to the length 
is that of 2,9880 feet in a fecond: confequently V — U, or 
2,9880- 1,1358 is equal to 1,8522 feet in a fecond. 
But as the velocities of recoil are known to be as the chords 
of the arcs through which the barrel afcends, it is not neceffary 
in order to determine the velocity of the bullet to compute the 
velocities V and U ; but the quantity V - U, or the difference 
of the velocities of the recoil when the given charge is fired 
with and without a bullet, may be computed from the value 
of the difference of the chords, by one operation. Thus the 
velocity anfwering to the chord 9,05 is that of 1,8522 feet in 
a fecond, which is juft equal to V - U, as was before found. 
The 
