THE ROYAL ARTILLERY INSTITUTION. 75 
Fig. 1. 
Snider.—Highest point of trajectory, 11' 10f // . Muzzle velocity, 1252*8 f.s. 
Martini-Henry. u u 8' If". n « 1362*7 f.s. 
Fig. 1 represents approximately the relative trajectories, at 500 yds. 
range, of the Martini-Henry rifle (*45-in. bore) and the Snider-Enfield 
(•577-in.), which were taken experimentally by the “ Committee on 
Small-Arms ” during their lengthened investigations into the merits 
of the different rifles proposed to them for adoption into the service 
in lieu of the Snider-Enfield. Taking 6 ft. as the height of an infantry 
soldier, the distance covered by the Martini-Henry at 500 yds. range 
is 104 yds., while the distance covered by the Snider-Enfield is only 
62 yds.; or, in other words, the margin allowed for error in judging 
distance is in the former case 104 yds., in the latter 62 yds. The 
practical method of determining the trajectory of any rifle is a very 
simple one; and, care being taken in the selection of a good marks¬ 
man, it may be determined with considerable accuracy. The rifle 
is carefully sighted for whatever range the trajectory is to be deter¬ 
mined. Suppose 500 yds. The marksman adjusts the sight of the rifle 
for 500 yds., and, at a distance of 100 yds. from the target, aims at a 
point on a level with his eye; the bullet hits the target higher than 
the point aimed at. A group of shots are thus made, and the point of 
mean impact of the group worked out; the vertical distance of the 
point of mean impact from the point aimed at is the height of the 
trajectory at 100 yds. The same process is repeated at 200, 300, and 
400 yds. respectively, whence the actual height of the trajectory at these 
distances is measured on the target. The trajectory may also be cal¬ 
culated when the muzzle velocity of the bullet and the resistance of the 
air to its motion are known. Trajectories calculated on known dynamical 
principles, agree very closely with those obtained by actual experiment. 
Flatness of trajectory depends principally on three conditions :— 
(1) The muzzle velocity of the projectile. 
(2) On the rate of diminution of that velocity caused by the resist¬ 
ance of the air. 
(3) On the velocity acquired by a body falling freely in the air. 
This last is the only one of the three conditions which is the same for 
every description of shell or bullet. For instance, a bullet of 480 grs. 
in weight, or a shell of 400 lbs. in weight, if allowed to fall freely in the 
air, will each acquire the same velocity—viz., 32*2 f,s, in 1 second. 
