220 CAUSES OF DRIFT. 
TABLE I, 
Practice at Shoeburyness on 15th March, 1861, with shot from a 40-pr. 
Armstrong rifled gun giving right-handed rotation ; weight of piece 
3l-cwt., charge 5 Ibs. Five rounds fired at each elevation ; no 
allowance for deflection in “ laying.” 
Mean deflection. 
Elevation. ikea 
Starch Right. Left. 
° yds. yds. ~ 
2 1061 06 = 
3 1421 10 = 
4 1769 3°6 = 
5 2113 6:2 — 
a 2687 164 — 
The above are fair average deflections and have not been chosen as 
being favourable to the statement—that right-handed rotation gives 
right deflection to projectiles with pointed or round heads. It is found 
as may be seen from this table and from others further on, that with 
this gun the derivation is hardly sensible at 1000 yards., and also that 
at this range a wind blowing across the line of fire from right to left 
may not only counteract the derivation but even deflect the shot to the 
left ; as however the range increases, the right deflections become very 
apparent. 
TABLE II. 
Practice at Shoeburyness on 9th April, 1862, with shot weighing about 
6U0-lbs., from a 32-pr. gun rifled on a French principle, and giving 
left-handed rotation ; charge, 5‘5-lbs. Fifteen rounds fired at each 
elevation ; no allowance for deflection in “laying.” 
Mean deflection. 
Hlevation, | Mean 
ge. Right. Left. 
fo) yds. yds. yds. 
2 824 — 15 
5 1672 — 61 
10 2891 — 198 
Of the 15 shot fired at 2°, two deflected to the right, one had no 
deflection, and the remaining eleven deflected to the left. All the shot 
fired at 5° and 10° deflected to the left, the deflection increasing with 
the angle of elevation. 
Professor Magnus, of Berlin, made a number of careful experiments 
some years ago, with both spherical and elongated projectiles, to ascer- 
tain the causes of deviations in flight ; but it will be necessary here to 
refer only to those with the latter. Before going on to these, however, 
it will be advisable to consider how the resistance of the air acts upon 
