Experiments upon Gunpowder. 49 



The form I would recommend for the bottom of the 

 bore is that of a hemisphere, and the vent should be 

 brought out directly through the side of the barrel, in a 

 line perpendicular to its axis, and pointing to the center 

 of the hemispheric concavity of the chamber. In this 

 case the vent would be the shortest possible ; it would 

 be the least liable to be obstructed, and the piece would 

 be more easily cleaned than if the bottom of the bore 

 was of any other form. All these advantages, and several 

 others not less important, would probably be gained by 

 making the bottom of the bore and vent of great guns 

 in the same manner. 



A new Method of determining the Velocities of Bullets. 



From the equality of action and reaction^ it appears 

 that the momentum of a gun must be precisely equal to 

 the momentum of its charge ; or that the weight of 

 the gun, multiplied into the velocity of its recoil, must 

 be in all cases just equal to the weights of the bullet 

 and of the powder (or the elastic fluid that is generated 

 from it), multiplied into their respective velocities : for 

 every particle of matter, whether solid or fluid, that 

 issues out of the mouth of a piece must be impelled 

 by the action of some power, which power must react 

 with equal force against the bottom of the bore. 



Even the fine, invisible, elastic fluid that is generated 

 from the powder in its inflammation cannot put itself in 

 motion without reacting against the gun at the same 

 time. Thus we see pieces, when they are fired with 

 powder alone, recoil, as well as when their charges are 

 made to impel a weight of shot, though the recoil is 

 not in the same degree in both cases. 



It is easy to determine the velocity of the recoil in 



VOL. I. 



