PRINCIPLES OP GUNNERY, 
45 
If — in equation (3) be assumed constant (which is very nearly the 
n 
case when similar guns are fired with charges of powder having the 
same proportion to the weights of the projectiles), then 
r wv 2 w 
energy of recoil a — X > 
w 
or energy of recoil oc muzzle energy of projectile x ; 
so that if the muzzle energy of projectile is constant, the energy of 
recoil varies directly as the weight of the projectile and inversely as the 
weight of the gun and carriage. The object of the artillerist is clearly 
to make the muzzle energy of the projectile a maximum, and to reduce 
the energy of recoil as much as possible consistent with the require¬ 
ments of the particular gun for range and mobility. 
The energy of recoil may be reduced either (1) by decreasing the How the 
weight of the projectile, (2) by decreasing the muzzle velocity, or (3) by MeSKnay 
increasing the weight of gun and carriage. But if the weight of the be reducedl 
projectile be much decreased, the gun will have less range and pene¬ 
tration, although there will be the advantage of carrying more rounds 
of ammunition in the limber and wagon; if the muzzle velocity be much 
decreased, the trajectory will not be so flat, the accuracy of fire will not 
be so good (especially with shrapnel shell) ; if the weight of the gun and 
carriage be much increased, it becomes more difficult to move it from 
place to place, and consequently its mobility becomes impaired. When 
the recoil cannot thus be reduced to the required limit, it becomes 
necessary to resort to mechanical or other means for checking it. 
The ratio of the weight of projectile to the weight of the gun 
and carriage is therefore determined by the nature of service for 
which it is to be employed—whether for indirect fire with low 
velocities, or for direct fire with high velocities—as well as the mobility 
required for the particular service. 
Major Kemmis’s Table of Comparison of M.L.R. Guns gives the Kemmis’s 
weight, length, and diameter of the cartridges and projectiles used servie? 
with them; the ratio of the weights of their projectiles and charges; ^dnanee 
the work done on projectile and cartridge; the weight of gun and 
carriage; the velocity of recoil; the work done in recoil upon, or 
energy of recoil of, gun and carriage; and the muzzle velocity corres¬ 
ponding to the charge. 
Example. —Required, the velocity of recoil of the 9-pr. M.L. gun of 
6 cwt. 
On referring to the table, weight of 9-pr. shell = 9*06 lbs., weight 
of charge = 1'75 lbs., muzzle velocity = 1390 f.s., weight of gun and 
carriage packed = 2049 lbs. Then from equation (1) 
V" = velocity of recoil == ~ ; 
