CAUSES OF DRIFT. 235 
stated) gaye right deflections, although, as already explained, the form 
of the head of these shot, rounded at the shoulder, would, in any case, 
have given a tendency in the same direction. 
Major-General J. S. Nicholson, R.A., when Commandant at Shoebury- 
ness, in 1889, pointed out to me, that with low charges and long times 
of flight, the drift of shells from the 8 inch howitzer, increased out of 
all proportion to range and time ; assigning as the reason that this was 
owing—“ to the greater friction on the lower surface of the projectile, 
due to the greater condensation of the atmosphere, from their rapidly 
increasing velocity of fall.” Thus, with 7-lbs. charge :— 
Range. Drift. Time of Flight. Angle of Elevation. 
yds. yds. secs. deg. mins, 
500 2:0 right 27 4 20 
1000 ICO op 57 ©) 20 
1500 220 ,, 89 14 55 
2000 40:0 ,, 12:9 22 25 
2500 85:0 ,, 19:2 356 
Lieut.-Colonel Bally, R.A., sent me some tables giving the results of 
recent practice at Shoeburyness* with shells fired from 6-in. B.L. 
Howitzers of 25 and 30 cwt., and from 9-in. M.L. guns at high angles 
and with small charges, which latter would give comparatively low 
velocities of rotation to the projectiles. (See Appendix IT.) 
In practice with the 6-in. Howitzers, using shells of about 119 lbs. 
weight and 27 inches in length, and charges of 12, 15, 18 and 19 ozs. of 
cordite powder, the shells appeared steady in flight at 43°, but at 51°, 
d7°, 65°, 68° and 70°, more or less unsteady, especially in the descending 
branch of the trajectory ; at 43°, 51° and 57°, the drifts were to the right, 
at the higher angles to the left. With charges of 13, 29 and 32 ozs. of 
cordite some of the shells at the higher angles drifted to the right. 
Some of the shells had a spiral motion during flight, due probably to 
the velocity of rotation being too low, like the gyrations of a top or 
gyroscope at the end of the spin. Some of the shells were found on 
the ground in a horizontal position, others were standing on their bases. 
Twenty Palliser shot, weighing from 3564 to 362 lbs., length 27:33 
inches, fired with a charge of 18} lbs., gave apparently regular results ; 
five rounds were fired at 30°, 45°, 60° and 70°, the ranges being longest 
at 45° and shortest at 70°, as might be expected, and the drift, which 
was always to the right, increased with the angle of elevation, as the 
time of flight was longer. Similar results were obtained with cast-steel 
common shells, weighing 3592 Ibs., length 32°85 inches, fired from the 
same gun with the same charge. Also with similar shells with a 124 lbs. 
charge, except at 70°, when the drifts were small, two being to the left 
and three to the right ; the projectiles being probably unsteady at this 
angle towards the end of the range. 
In other practice from the same gun, to ascertain if the shelly fell 
point first with the 12} Ibs. charge at 60°, 65° and 70°, the drifts appear 
to have been to the right, but two of the shells, which were fused, were 
blind ; the shells appeared to be steady in ascent but erratic when 
descending, the base at first falling till the shell was nearly vertical, 
and afterwards assuming a more or less horizontal position, and finally 
slewing slowly end for end, as the report says, 7.¢., “the projectile was 
* T intended to allude to these tables in my lecture and make the remarks meeriaal 
here, but Major Abdy stopped me, thinking that they would be produced by another 
officer, which however was not done. 
