SCIENTIFIC TRACTS. 



NUMBER XXII. 



MILITARY PROJECTILES. 



ANALYSIS. 



Nature of the path of a projectile. Primitive contrivances ; Sim- 

 ple human strength ; Sling ; Dart. Elasticity of various substances. 

 Bow and Arrow ; Ballista ; Catapulta. Description of the siege of 

 Syracuse. 



Invention of gunpowder. Cannon. Mortars. Shells. Carcas- 

 ses. Description of the shelling of a fort in India. Howitzers, Car- 

 ronades. Portable fire-arms. Theory of the rifle. History of 

 the science of Gunnery. Calculations and experiments. Eprouvette . 

 Ballistic Pendulum. 



THEORY OF PROJECTILES. 



Whenever a body is projected, as for example, a cannoa 

 ball, it is plain that it is acted upon by two forces, the at- 

 traction of gravitation draw ing it towards the earth, and 

 the impelling forr.c, whatever that may be. In order, 

 then, to ascertain the path of the body, we must consider 

 the nature of these two forces, first, separately, and then 

 in their united action upon the body projected. 



It has been already shown in our tract on Gravitation, 

 that bodies when falling freely, descend in the first se- 

 cond 16.1 feet, in the next second 48.3, making in the 

 two 64.4, or four times the space passed over in one. 

 In the same manner, in thnc seconds, a body will fall nine 

 times as far as in one, and in four seconds sixteen times 

 as far ; and, universally, the space through which the 

 body will descend will be as the square of the time, 



VOL. I. NO. XXII. 47 



