Experiments upon Gunpowder. 29 



first was occasioned more by the heat which the barrel 

 had acquired in the first experiment than by the posi- 

 tion of the vent, or any other circumstance ; for I have 

 since found, upon repeated trials, that the force of any 

 given charge of powder is considerably greater when it 

 is fired in a piece that has been previously heated by 

 firing, or by any other means, than when the piece has 

 not been heated. Everybody that is acquainted with 

 artillery knows that the recoil of great guns is much 

 more violent after the second or third discharge than it 

 is at first ; and on shipboard, where it is necessary to 

 attend to the recoil of the guns, in order to prevent 

 very dangerous accidents that might be occasioned by 

 It, the constant practice has been in our navy, and I 

 believe on board the ships of all other nations, to lessen 

 the quantity of powder after the first four or five 

 rounds ; our 32 pounders, for instance, are commonly 

 fired with 14 lbs. of powder at the beginning of an 

 action, but the charge is very soon reduced to 1 1 lbs., 

 and afterwards to 9 lbs., and the filled cartridges are 

 prepared accordingly. 



By the recoil, it should seem that the powder exerted 

 a greater force also in the fourth experiment, being the 

 second upon the second day, than it did upon the third, 

 or the first upon that day ; but, the pendulum giving 

 way, it was not possible to compare the velocities of the 

 bullets in the manner we did in the two experiments 

 mentioned above. 



This augmentation of the force of powder, when it 

 is fired in a piece that is' warm, may be accounted for in 

 the following manner. There is no substance we are 

 acquainted with that does not require to be heated 

 before it will burn ; even gunpowder is not inflammable 



