282 Mr. Thompson’s Experiments 
The weight of the barrel, together with its carriage, was 
47 J pounds, to which three quarters of a pound is to be added 
on account of the weight of the rods by which it was fuf- 
pended, which makes W — 48 pounds, or 336,000 grains, 
and the weight of the bullet was 580 grains. B is therefore 
to W as 580 is to 336,000, that is, as 1 is to 579,31 very 
nearly ; and v ( = is equal to V - U x 579,31 . 
The value of V - U anfwcring to the experiments before 
mentioned was found to be 1,8522 ; confequently the velocity 
of the bullets ( = v) was 1,8522 * 579,3 1 ~ 1073 feet in a fe- 
cond, which is extremely near 1083 feet in a fecond, the mean 
of the velocities, as they were determined by the pendulum. 
But the computation for determining the velocity of a bullet 
upon thefe principles may be rendered ftill more fimple and eafy 
in practice ; for the velocities of the recoil being as the chords 
meafured upon the ribbon, if 
c is put equal to the chord of the recoil expreffed in 
Englifh inches, when the piece is fired with powder 
only, and 
C ~ the chord when a bullet is difeharged by the fame 
charge, 
then C - c will be as V - U ; and confequently as ^ , 
which meafures the velocity of the bullet, the ratio of W to B 
remaining the fame. 
If therefore we fuppofe a cafe in which C - c is equal to one 
inch, and the velocity of the bullet is computed from that 
chord, the velocity in any other cafe, wherein C - c is greater 
or lefs than one inch, will be found by multiplying the dif- 
ference of the chords C and c by the velocity that anfwers to a 
difference of one inch. 
The 
