THE ROYAL ARTILLERY INSTITUTION. 
301 
if cast-iron shot were used, a very high velocity was needed to pierce the 
plate, but with hard materials, such as steel or chilled iron, a high 
velocity was not so necessary, the effect being equal when shots struck 
with equal energy, which might be compounded in any proportion 
between weight and velocity within practical limits. 
With regard to the best shape of head to be given to the projectile, 
it was found that against unbacked plates the shape of head, whether 
flat, hemispherical, or pointed, made very little difference; but against 
backed plates the pointed ogival head had a great advantage. When 
hemispherical or flat-headed projectiles pierced a backed plate, they 
punched out a piece of the iron and carried it before them into the 
backing, and could not rid themselves of it; but the ogival-headed shot 
tore a way for itself through the plate, bending back its edges into the 
backing, but carrying no portion of the iron before it. It was found, 
however, that the ogival head did not answer so well with steel as with 
chilled iron. 
It was also found that with blunt heads (hemispherical and flat) much 
energy was wasted in setting up the head—that is, in flattening it out 
and bulging the shot; whereas the pointed projectiles passed through 
almost unchanged in shape. Blunt-headed projectiles also suffer more 
resistance from the air. 
In firing against inclined plates, it was found that the pointed pro¬ 
jectiles dug their noses into the plates and turned round till their axes 
were almost at right angles to the plate, and were therefore in the most 
favourable position for penetration; whereas the blunt-headed shot 
ploughed up the metal of the plates till they were brought to rest 
by the accumulation in front of them, their axes being still parallel 
to their original position. It was found that ogival-headed shot 
would generally not glance if the angle between the line of fire 
and the plate was not less than the angle made with the axis of the 
shot by a tangent to the curve of the head at the point of the shot. 
Shell were fired at the plates with bursting charges and without 
fuzes, and it was found that steel and chilled Palliser shells would 
penetrate the plates, and explode after passing through. 
When Palliser projectiles were fired at iron plates, it was found that 
the heads passed through entire, but the bodies always broke up. If 
the projectile pierced the side of a ship, this breaking up would be very 
destructive, the pieces acting as langridge; but it is probable that a 
certain amount of energy is so lost. 
Palliser projectiles with ogival heads are more effective than steel 
ones, if they are of good quality, and cost little more than one-fifth as 
much. It was found very difficult to get solid Palliser shot homoge¬ 
neous throughout; they are therefore now cast with a hollow core, the 
heads being cast in chill and the bodies in sand. The hollow does not 
extend into the head in the case of shot, but it does * in shell, the walls 
of which are rather thinner. Good results are obtained with projectiles 
manufactured in the new way. 
It is worthy of remark that timber backing to iron plates has been 
set on fire by Palliser shot without bursting charges. 
W e may therefore sum up the conditions requisite for efficient firing 
at armour plating as follows ;—- 
