526 



MIL1TARV PROJECTILES. 



- End of the third second. 



- End of the fourth second. 



This accelerated motion may be easily represented to 

 the eye thus : 



Beginning of the fall. 



1 - End of the first second. In this line each little di- 



vision represents 16.1 feet, 



I End of the second second, as that is the space through 

 which a body falls in the first 

 second. 



The other force to which 

 a projected body is subject, 



10 - is the impulse which is given 



it. This is much more sim- 

 ple in its character, for, if 

 we leave out of the consid- 

 eration the resistance of the 

 air, the effect of this impulse 

 is uniform. Motion once imparted continues unchang- 

 ed, unless some foreign force affects it. Consequently, 

 the tendency of the force of impulse is to carry forward 

 the body uniformly in a straight line. 



These two forces now must be combined in order to 

 show the real path of the projectile. Their combina- 

 tion is usually illustrated by the following diagram. 



The line o c repre- 

 sents the tendency of f i ?,3' 

 gravitation, with the ll'_^J^ 

 seconds marked on 

 the left ; o 4'b repre- aj 

 sents the tendency of 

 the projectile force, 

 which being uniform, 

 the line is divided 

 into equal parts, 

 which are marked by 

 the seconds above. 

 These parts compar- 

 ed with one of the 

 divisions of the per- 

 pendicular line appear to be about five times as long ; 

 and as these divisions stand for about sixteen feet, the 

 divisions of the other line would represent about seven- 



at' 



