Experiments upon Gunpowder. 39 



escape, will be very languid, as will be the heat that is 

 generated by it. 



But if, instead of giving way with so much difficulty, 

 the bullet be much lighter, so as to afford but little 

 resistance to the elastic fluid in making its escape, or if 

 the powder be fired without any bullet at all, then, there 

 being little or nothing to oppose the flame in its passage 

 through the bore, it will expand itself with an amazing 

 velocity, and its action upon the gun will cease almost 

 in an instant, the strained metal will restore itself with 

 a very rapid motion, and a sharp vibration will ensue, 

 by which the pieqe will be much heated. 



Of the Effect of ramming the Powder in the Chamber of 



the Piece. 



The charge, consisting of 218 grains of powder, being 

 put gently into the bore of the piece in a cartridge of 

 very fine paper without being rammed, the velocity of 

 the bullets at a mean of the 4<Dth, 41 st, 42d, and 47th 

 experiments was at the rate of 1225 feet in a second; 

 but in the 68th, 69th, and yoth experiments, when the 

 same quantity of powder was rammed down with five 

 or six hard strokes of the ramrod, the mean velocity 

 was 1329 feet in a second. Now the total force or pres- 

 sure exerted by the charge upon the bullet is as the 

 square of its velocity, and 1329 is to 1225 as 1.1776 

 is to i, or nearly as 6 is to 5 ; and in that proportion 

 was the force of the given charge of powder increased 

 by being rammed. 



In the 7ist experiment the powder was also rammed, 

 but the vent, instead of being at the bottom of the 

 bore, was at 1.3, and the velocity of the bullet was very 

 considerably diminished, being only at the rate of 1080 



