108 



Mean velocity = 909-08 feet. 



Mean quantity of motion = 96*63 lbs. 



Mean quantity of Work = 1364 lbs. lifted one foot. 



Table V. — Carhine. 



No. 



n. 



b. 



V. 







In. 



Ft. 



1. 



989 



9-00 



1275-21 



2. 





9-12 



1292-92 



3. 





8-75 



1239-78 



4. 





8-62 



1222-07 



Mean velocity = 1257*49 feet. 



Mean quantity of motion = 70*24 lbs. 



Mean quantity of Work = 1371 lbs. lifted one foot. 



If we assume that the force developed by the explosion of the powder, 

 diminished by the friction of the barrel, is constant, it is easy to deduce 

 the following expression for the velocity — 



*=Qx^/l, (4) 



m 



in which Q denotes a constant depending on the quantity of powder and 

 diameter of the rifle, s the length of the barrel, and m the weight of the 

 bullet. 



Taking the velocity of the belted bullet, 1021-7 feet, as our datum, 

 and calculating the velocities of the others from (4), we find 



Table VI. — Theoretical and observed Velocities. 





Calculated. 



Observed. 



Difference. 





Ft. 



Ft. 



Ft. 



Minie bullet in 2-grooved rifle, 



849-0 



847*0 



+ 2-0 





866-8 



863-7 



+ 3*1 





915-0 



909*08 



+ 5*92 





1083-7 



1257*49 



-173-79 



The agreement ot these results is very striking in the case of the 

 rifles, and proves the truth of equation (4) ; and the disagreement in the 

 case of the carbine proves, as might be expected, that the force of the 

 powder is greater in the smooth bore than in the rifle. From the pre- 

 ceding results, we may assert, with confidence, that the velocity with 

 which a bullet is propelled from, a rifle by a given charge of powder de- 

 pends mainly on the weight of the bullet and the length of the barrel, 



