320 MEASURING THE STRIKING FORCE OF SHOT. 



the force reacted upon its vehicle, the projectile, so 

 suddenly as to destroy the position of its particles, 

 and thus cause it to assume a larger surface to be 

 resisted upon in its further passage, and the larger 

 the surface the greater the resistance, and consequently 

 the less the penetration. Had the savans who con- 

 ducted these experiments gone further, they would 

 have found the point for greatest penetration depend- 

 ent upon the tenacity and form of the projectile and 

 the nature of the object resisting, as well as upon the 

 velocity. From the above it is obvious, the simple 

 depth of penetration in a target where the reactionary 

 force is sufficient to destroy the original shape of the 

 projectile, can never be taken as a reliable index of its 

 force. 



Let us apply this law to the system of measurement 

 employed at the late gun-trials. If in those trials the 

 pellets of shot which have struck the Pettit pad, as 

 the targets in use are called, are examined, they will 

 be found much flattened and mis-shapen, and those 

 least so will have penetrated farthest. In actual ex- 

 periment, with a charge of 3 drams of powder and 1^ 

 ounces of shot, 37 sheets of such a pad were pene- 

 trated ; with 6 drams of powder, other conditions the 

 same, only 23 sheets were penetrated; but the pellets 

 of shot in the latter case were flattened to almost 



