MILITARY PROJECTILES. 527 



tyfive feet each; so that the figure corresponds with 

 the condition of a body thrown a little upwards with a 

 velocity of about seventy five feet per second. Now the 

 effect of the projectile force will be to carry it on, during 

 the first second, as far as 61', while during the same 

 time, gravitation will bring it down from the point 61' 

 which it would have reached, as much as the distance 

 from o to !'. The point then at which the body will 

 be found is m. In the same manner we find the points 

 n, 0, p, the successive places of the body at the end of 

 the second, third, and fourth seconds. The whole path 

 of the projectile will be the curve o, m, n, o, p. 



It is not our present purpose to go any farther into the 

 theory of projectiles, but to give some practical informa- 

 tion, for the benefit of the general reader, in regard to 

 the contrivances for propelling heavy bodies for the pur-- 

 poses of war. The above theoretical view was necessa- 

 ry to illustrate some remarks to be made in the sequel. 



PRIMITIVE CONTRIVANCES. 



1 . The unassisted strength of the human arm was the 

 first force which was applied to the purpose of projecting 

 bodies for offensive purposes. Stones, clubs and spears 

 were the first rude weapons. The muscular strength 

 which gives motion to such projectiles is not, strictly 

 speaking, directly applied to them by impulse. Jt is em- 

 ployed in giving a circular motion to the arm, the body 

 to be projected being thrown of by the centrifugal force. 

 Consequently the force given to the projectile will be pro- 

 portional, not only to the strength of the individual, but 

 to the length of his arm, as this would increase the length 

 of the arc through which the hand moves, and conse- 

 quently its velocity. A very obvious mode of increasing 

 the power, therefore, would be to increase by artificial 

 means this length, which gives rise to the construction of 

 the second species of weapons. 



2. The sling and the dart, two modes of projecting 

 bodies which evidently derive their power from increas- 

 ing the velocity of the projectile, by increasing the arc 

 through which it moves, and which differ from each other, 



