Experiments upon Gimpowder. 53 



and c by the velocity that answers to a difference of one 

 inch. 



The length of the parallel rods by which the barrel 

 was suspended being 64 inches, the velocity of the 

 recoil answering to C c= i inch, measured upon 

 the ribbon, is 0.204655 parts of a foot in a second ; 

 and, this is also, in this case, the value of V U; the 

 velocity of the bullet is therefore v = 0.204655 X 

 = 118.35 f eet m a secon d. 



Consequently the velocity of the bullet, expressed in 

 second, may, in all cases, be found by multiply- 

 ing the difference of the chords C and c by 118.35, tne 

 weight of the barrel, the length of the rods by which it 

 is suspended, and the weight of the bullet remaining 

 the same ; 'and this, whatever the charge of powder may 

 be that is made use of, and however it may differ in 

 strength or goodness. 



According to this rule, the velocities of the bullets in 

 the following experiments have been computed from the 

 recoil ; and by comparing them with the velocities 

 shewn by the pendulum, we shall be enabled to judge of 

 the accuracy of this new method of determining the 

 velocities of bullets. 



In the y6th and yyth experiments, when the piece was 

 fired with 145 grains of powder and a bullet, the recoil 

 was 13.25 and 13.15, or 13.2 at a mean; and with the 

 same charge of powder, without a bullet, the recoil was 

 4.5 and 4.3, or 4.4 at a mean (see the 84th and 93d 

 experiments). 



C c is therefore 13.2 4.4 = 8.8 inches, and the 

 velocity of the bullets = 8.8 X 118.35= IO 45 ^" eet * n 

 a second. The mean of the velocities as they were 

 determined by the pendulum is that of 1040 feet in a 



