36 ^^ PERCUSSION. 



chanic effect producible by bodies moving with different 



quantities of impetus have been as clearly traced by th'e 



same acrurate experimentalist*. 



Farther consi- But there is one view, in which the comparative forces 



tferatjons re- ^j- impact of different bodies was not examined by Smea- 

 specting forces. * -' 



TON, and it may be worth while to shew that when the 



whole energy of a body A is employed wifhout loss in 

 giving velocity to a second body B, the impetus which B 

 receives is in all cases equal to that of A, and the force 

 transferred to B, or by it to any third body C, (if also 

 comriiunicated without loss, and duly estimated as a me- 

 chanic force,) is always equal to that from which it ori- 

 ginated. 



As the simplest case of entire transfer, the body A 

 may be supposed to act upon B in a direct line through 

 the medium of a lisjht spring, so contrived that the spring 

 is prevented by a ratchet from returning in the direction 

 towards A, but expands again entirely in the direction 

 towards B, and by that means exerts the whole force 

 which had been wound up by the action of A, in giving 

 motion to B alone. In this case, since the moving force 

 of the spring is the same upon each of the bodies, the 

 accelerating force acting upon B at each point is to the 

 retarding force opposed to A at the corresponding points 

 in the reciprocal ratio oi the bodies, and the squares of 

 the velocities produced and destroyed by its action 

 through a given space will consequently be in that same 

 ratio. The momentum, which is in the simple reciprocal 

 ratio of the bodies, might consequently be increased at 

 pleasure by the means , proposed, in the subduplicate 

 ratio of the bodies employed ; and if momentum Avere an 

 efficient force capable of reproducing itself, and of over- 

 coming friction in proportion to its estimated magnitude, 

 the additional force acquired by such a means of increase, 

 might be employed for counteracting the usual resistances, 

 and perpetual motion would be easily effected. But 

 since the impetus remains; unaltered, it is evident that 

 the utmost which the body B could effect in return would 

 be the reproduction of A's velocity, and restitution of its 



• Phil. Trans. Vol. LXXTI. 337. 



entire 



