182 
MINUTES OF PROCEEDINGS OF 
Now, if cylindrical or flat-headed projectiles be fired instead of round 
pointed shot, the direction of the derivation is reversed; that is to say—a 
flat-headed shot fired with right-handed rotation deflects to the left, and one 
fired with left-handed rotation to the right. To prove that this is the case a 
number of cylindrical shot were made under the direction of the 0. S. Com¬ 
mittee and fired at Shoeburyness alternately with ordinary service cylindro- 
conoidal shot from the same gun, a breech-loading Armstrong 40-pr. Some 
of the cylindrical shot made for this experiment had their centres of gravity 
about the centre of the figure, in others the centre of gravity was nearer to 
the base, and in the rest nearer to the point of the projectile; the prepon¬ 
derance was given either by the iron of the shot or by lead. As however it 
was only required to establish the fact of the left deflection and not its 
amount, the position of the centre of gravity of shot fired at the moderate 
ranges found practicable was comparatively of little importance. 
It soon became apparent from the practice, that to obtain comparative 
results, it was necessary to fire at angles of elevation giving moderate ranges, 
for at short ranges the derivation is not sensible, while at long ranges the 
velocity of rotation given by the gun was not high enough to prevent the 
cylindrical or flat-headed shot from turning over during flight. It may be 
as well to remark here, that flat-headed shot require a much higher velocity 
of rotation than projectiles with pointed or rounded heads, “ for the current 
of air meeting the shot, instead of having merely, as with the latter forms, to 
pass round the pointed head, presses with the flat head upon a surface almost 
at right angles to the previous direction of the current, and consequently 
exerts a very much greater force proportionally, tending to upset the 
shot.”* 
In the following tables the ordinary cylindro-conoidal shot will be termed 
service shot, and the cylindrical or flat-headed experimental shot will be called 
special shot , the position of the centre of gravity of the latter being also 
given. 
Yery calm days were selected for the practice, so that the results might 
be affected as little as possible by wind. 
Both service and special shot were fired at each day’s practice from the 
same 40-pr. Armstrong gun mounted on a travelling carriage; weight of 
piece 32cwt., calibre 4-75 in., spiral 1 turn in 37 calibres, and number of 
grooves 56. 
* “ The motion of projectiles fired from Rifled Arms/’ p. 33. By Major C. H. Owen, R.A. 
