$p6 Mr. Thompson’s Experiments 
value for C the velocities of the bullets in the before men- 
tioned experiments appear to be, 
Vent at O. Vent at 1,3. 
1243 and 1283 by the recoil 
which is extremely near 1225 and 1276 the velocities 
fhewn by the pendulum. 
It is to be remembered, that the 7 2d and 73d experiments, from 
which we before determined the recoil with the given charge 
of powder without a bullet, were not made upon the fame day 
with the experiments before mentioned ; and it is well known, 
that the force of powder is different upon different days. And 
it is worthy of remark, that in thofe two experiments the 
Hrength of government powder appeared to be confiderably the 
greatefh I mention thefe circumftances to fhew the probability 
there is, that the recoil in thofe experiments, from fome un- 
known caufe, was greater than it ought to have been, or ra- 
ther than it would have been, had the experiments been made 
at the fame time when the experiments with the bullets were 
made ; or at any other time under the fame circumftances. 
As this method of determining the velocities of the bullets 
did not occur to me till after I had finilhed the courfe of my 
experiments, and had taken down my apparatus, I have not 
had an opportunity of afeertaining the recoil, with and with- 
out a bullet, with that degree of precifion that I could wifh. 
If I had thought of it fooner, or if I had recollected that paf- 
fage in Mr. robins’s new Principles of Gunnery, where he 
fays, 44 The part of the recoil, arifing from the expansion of 
44 the powder alone, is found to be no greater when it impels 
44 a leaden bullet before it, than when the fame quantity is fired 
* 4 without any wad to confine it I fay, if that paflage had 
occurred 
