MEASURING THE STRIKING FORCE OF SHOT. 319 



to Other bodies a part or the whole of its motion ; but 

 just the amount it imparts it loses ; it cannot give to 

 others and still retain all of its own. When a projec- 

 tile leaves the muzzle of a gun it has a certain variable 

 amount of force imparted to it by the explosion of the 

 gunpowder ; now if this projectile met with no resist- 

 ance, it would travel forever, it being another law of 

 nature that no body in motion has in itself the power 

 to reduce or stop that motion. But as soon as the 

 power increasing the velocity of a projectile is taken 

 from it, it begins to lose its motion from the direct 

 resistance and friction of the atmosphere, to each par- 

 ticle of which with which it comes in contact it im- 

 parts some of its own motion, and this alone would be 

 sufficient in a short time to bring it to a state of com- 

 plete rest. For these reasons, if there is no extrane- 

 ous force applied (which is too absurd to be supposa- 

 ble), the velocity of a projectile must be less at 190 

 yards from the muzzle than at any preceding point in 

 its flight. The simple reason for its increased pene- 

 tration is the stability of another law of motion that 

 time is required to impart motion, or, in other words, 

 to overcome inertia. At distances less than 190 yards 

 the velocity was so great that sufficient time v/as not 

 given to communicate the motion of the projectile to 

 the particles of wood resisting, and; as a consequence, 



