Mr. 
Thompson’s Experiment s? 
x 
pear upon mfpedling the curvature of the line m 9 n, fig. i6k- 
Btit I forbear to infill further upon this matter.,. ■ 
As I have, made an, allowance for the.- refinance of the air in 
thefe experiments, it may be expected that I. fhould do it in all 
other cafes but,, 1 think, it will' appear upon enquiry, that 
the diminution of the velocities of the bullets on that account' 
was in general fo inconhderable that it might fifely be neg- 
lected : thus,, for. in fiance, In the experiments with. an ounce 
of powder, when the velocity of the bullet was more than 
1750 feet 111 a fecoiid, the diminution turns out no. more than 
about 25 or: 30.. feet in- a fecond, though we fiippofe: the full 
refiflance to have begun fo near as two feet from. the mouth of 
the piece..;: and in. all cafes .where the velocities were lefs* the 
effect of. the refiflatice was. lefs in a much greater proportion 
and even in this unftance there is reafon to think, that the di- 
minution of the velocity as- we. have determined it is too great ; 
for the flame of gun-powder expands with fuch an amazing 
rapidity, that it is fcarcely to be fuppofed' but' that, it; follows 
the bullet, and continues to act" upon it more than two feet, ot 
even four feet,, from the gun, and when the velocity of the. 
bullet is lefs, its action upon it. muff he. fenfible at- a hill, 
greater diftance. 
Witli 2.1 8 : grains of powder the recoil appears to have been 
very uniform ; but ’ if the velocities of the bullets are deter- 
mined from the recoil in the 40th. and feven following experi- 
ments, when this charge was made life of, and from the recoil 
without a bullet in the pad and 73d experiments, the velocities 
will turn out; confiderably too fmalh, as we fhall fee by making 
the computation. 
The. 
