58 
PRINCIPLES OP GUNNERY. 
Circum 
stances 
affecting 
muzzle 
velocity. 
Allowing 1 a small per-centage for loss of energy, due to the com¬ 
munication of heat, &c., &c., to the gun—which can only be judged 
by experience—a very close approximation to the muzzle velocity may 
be obtained. In this case, deduct 5 per cent, from the maximum 
theoretic work, in order to approximate to the work actually realised, 
which would then be 10,400 ft. tons. Substituting in formula (2), 
muzzle velocity == 2 X 
32'2 
10400 x 2240 
800 
= 1369 f.s.: 
which is very nearly the muzzle velocity determined by experiment. 
The per-centage allowed in any case depends on the modifications 
alluded to in p. 54—viz., nature of the powder, method of ignition 
adopted, and the weight of the projectile, besides the amount of air¬ 
space allowed for the cartridge—which will be considered in due 
course. (Fide p. 61.) 
Circumstances which affect the muzzle velocities of projectiles fired 
out of rifled ordnance may be classified thus :— 
Charge of powder. 
Nature of powder. 
Weight of projectile. 
Length of bore. 
Calibre. 
Diameter of chamber. 
Cubic space occupied by charge. 
Windage. 
Position of vent. 
Twist of rifling. 
Charge of 
powder. 
By the employment 
9 -pr. R.M.L. of 8 cwt * 
Charge. 
Weight 
of shot. 
M.V. 
lbs. 
lbs. 
f.s. 
1-75 
9 
1344 
2-0 
n 
1356 
2-25 
i 
1432 
2*5 
// 
1457 
2*75 
II 
1453 
2-0 
12 
1196 
2*25 
n 
1257 
2-5 
1 
1287 
2-75 
| 
1284 
3-0 
" 
1259 
1 
Length of bore, 63’5 ins. 
Calibre . 3 « 
of small charges of powder, the muzzle velo¬ 
city of the projectile may be as low as 
desirable. The effect of increasing the charge 
by equal increments, is to increase the muzzle 
velocity rapidly at first (vide table), then less 
rapidly—depending on the nature of the 
powder employed and the length and calibre 
of the gun. 
By a continued increase of the charge, the 
muzzle velocity continues to increase slowly 
until a point is reached (seldom or never 
attained in practice) when the muzzle velocity 
would be the greatest possible under the 
circumstances. Any further increase of the 
charge would then have the effect of dimin¬ 
ishing the velocity until the bore was nearly 
full of powder, when the velocity would be 
very slight. It is evident that the larger the 
charge, the longer the cartridge must be ; so 
that after a certain limit is reached, the explo¬ 
sion of the charge becomes incomplete, and 
the consequently reduced pressure acts on the 
projectile through an increasingly shorter 
distance. 
* Experiments carried on in the Eoyal Gun Factories, Woolwich, 1873, by Major Maitland, E.A. 
