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MINUTES or PROCEEDINGS OF 
There are two methods in which armoured ships may be attacked— 
either by “ punching ” holes through their plates and sides, or by what 
is termed “racking”—that is, ruining the structure by the shaking 
effect produced by the impact of heavy projectiles that do not pierce the 
armour. It was seen in the last American war what an immense 
amount of battering an armoured vessel could stand without being dis¬ 
abled, as long as her plates were not pierced; and we in this country 
have decided that the method of attack by punching is the most 
effective. 
The principles which affect the punching power of projectiles have 
been worked out, partly by mathematical investigation and partly by 
experiment. Before stating them, it will be necessary to define the 
term “energy.” 
“Energy ” is the amount of work in a shot when it strikes an object, 
and is calculated thus :— 
— energy in foot-pounds; 
where 
w = weight of shot in lbs., 
v = remaining velocity in ft. per second, 
g = accelerating force of gravity. 
It is found that the power of piercing unbacked armour plates 
decreases as the diameter of the projectile increases; and therefore 
energy is generally expressed in foot-tons per inch of circumference of 
the projectile, or 
-- WV - - - -- - - — energy in foot-tons per inch of circumference. 
4 vrg x 2240 ^ 
The following principles were found to hold good in practice against 
armour plates:— 
Solid steel shot, with similar forms of head and of equal diameter, 
penetrate unbacked iron plates with equal facility if they strike with 
equal energy, however that energy may be compounded of weight 
and velocity within practical limits—that is to say, the same effect is 
produced by a light shot with high velocity, as with a heavy shot with 
low velocity. 
Solid steel shot of different diameters penetrate with equal facility if 
they strike with energy proportionate to their diameters. 
The resistance of unbacked iron plates of different thicknesses varies 
as the square of their thicknesses. 
From the first two of these principles it may be easily seen that the 
law may be generally stated that solid steel shot of similar forms of 
head penetrate unbacked iron plates with equal facility, if they strike 
with equal energy per inch of circumference. 
In firing obliquely at iron plates, it was found that in all cases, as long 
as the projectile did not glance off the plate, the penetrating effect was 
directly proportional to the sine of the angle between the line of fire 
and the face of the plate. 
On experimenting with shot of different materials, it was found that 
