TRACT 34.

IN GUNNERY.

315

arc described by it in the recoil, the velocity of the ballwill be found by this proportion ; namely, as the weight ofthe ball is to the weight of the gun, so is the velocity of thegun, to the velocity of the ball: that is, if the weight ofpowder had no effect on the recoil.

10. This description may suffice to convey a general ideaof the nature and principles of the experiment, for deter-mining the velocity with which a ball is projected, by anycharge of powder, from a piece of ordnance. But it is tobe observed that, besides the centre of oscillation, and theweights of the ball and pendulum, or gun, the effect of theblow depends also on the place of the centre of gravityin the pendulum or gun, and that of the point struck, orthe place where the force is exerted ; for it is evident thatthe arch of vibration will be greater or less, according tothe situation of these two points also. It will thereforebe necessary now to give a more particular description of themachinery, and of the methods of finding the aforesaidrequisites; and then we shall investigate our general rulesfor determining the velocity of the ball, in all cases, fromthem and the chord of the arc of vibration, either of thependulum or gun,

Of the Guns, Powder, Balls, and Machinery employed inthese Experiments.

11. Five very fine brass one-pounder guns were cast andprepared, in Woolwich Warren, for these experiments, andbored as true as possible; the common diameter of their borebeing 2'02, or 2 inches and parts of an inch. Threeof these, namely, n*.l,2,3, were nearly of the same weight,but of the respective lengths of 15, 20, and 30 calibers; inorder to ascertain the effect of different lengths of bore,with the same weight of gun, powder, and ball. Theother two, n os . 4 and 5, were heavier, and of 40 calibers inlength; in order to obtain the effects of the longest pieces.