a86 
Mr. Thompson’s 'Experiments 
Vent at o. Vent at 2,6 
By the recoil - - 1822 1771 
And by the pendulum they were 1764 1751 
The difference is only - 4-58 and 4-20 feet 
in a fecond, which is lefs than what frequently occurs in re- 
peating the fame experiment. 
In the nth, 12th, 13th, and 14th experiments, when the 
piece was fired with 310 grains of powder and a bullet, the 
recoil was 24,69, 24,95, 2 4>9> and 24,9 : and in the 15th, 
1 6th, 1 8th, and 19th experimentss with 330 grains of pow- 
der, the recoil was 26,2, 26,2, 26,3, and 26,4. The regu- 
larity of thefe numbers is very {hiking ; and though we ; 
cannot compare the velocities of the bullets determined by the j 
two methods as w r e have done in other cafes (as there are rea- 
fons to believe, that the velocities, as they are fet down in the ; 
tables, are not much to be depended on, and as the recoil, with 
the given charge of 310 grains of powder without a bullet, is i 
not known) yet the regularity of the recoil in thefe experi- j 
meats affords good grounds to conclude, that the method of 
determining the velocities of bullets founded upon it muft be 
verv accurate. 
But of all the experiments thofe numbered from 84 to 92- 
inclufive afford the ftrongeft proof of the accuracy of this me- j 
thod. In thofe every poffible precaution was taken to prevent 1 
errors arifing from adventitious circumflances, and the weights 
of the bullets and their velocities were fo various, that the uni* > 
form agreement of the two methods of determining the velo- 
cities in thofe trials amounts almoft to a demon ftration of the 
truth of the principles upon which this new method is founded. ! 
By 
