ARMOURED DEFENCES. 
329 
them, and backing of timber and iron behind them. I must also 
mention two targets composed of 8-in. wrought-iron plates backed 
by blocks of chilled cast-iron of Gregorini ” metal, 14 ins. thick. 
In one of these the chilled blocks touched the front armour, in the 
other 12 ins. of wood were interposed. 
In all the targets there was the same total thickness of 4 ft. 4 ins., 
made up of about 22 ins. of armour and 30 ins. of timber and skin. 
The general result of the trial was this :— 
One steel plate was a good deal cracked, and had its end knocked 
away by two blows from a 10-in. and one from an 11-in. gun throwing 
chilled cast-iron projectiles, and the fourth round from the 100-ton 
gun with a 2000-lb. chilled cast-iron projectile striking with a velocity 
of 1500 f.s., and a muzzle energy of 31,000 ft. tons, dashed the plate to 
pieces, though it apparently could not quite perforate it. The other 
thick steel plate was completely demolished by a single round from 
the same 100-ton gun. 
The thick wrought-iron plate made in England was much less 
injured generally by the lighter guns than was the steel plate, though 
the indents in it were deeper, but the 100-ton gun sent its shot through 
all the iron plates, and also broke them in two. 
The “ plate-upon-plate ” targets did not do so well as the solid 
plates, and the targets with the chilled iron backings entirely suc¬ 
cumbed to a single blow on each from the 100-ton gun. 
The results of the trial were seriously invalidated by the narrowness 
of the plates used ; a width of 4 ft. 7 ins. being altogether too little for 
a plate which is to receive a 17-in. shot, and, on this account, these 
costly and elaborate trials at Spezia have afforded much less useful 
information than they ought to have given. 
The brittleness of the steel, and its consequent incapacity for resist¬ 
ance to repeated blows, is a striking feature of these trials; the failure 
of the plate-upon-plate targets, through their being a bad imitation of 
our construction, is another ; the utter collapse of the target with the 
chilled iron blocks is a third ; and the defective plan of holding armour 
by simply screwing bolts into the backs of plates is a fourth. 
It is to be regretted, also, that these trials did not give us a more exact 
measure of the armour-piercing power of the 100-ton gun, which was a 
counterpart of the four which we are to mount at Gibraltar and Malta. 
In 1879 the Italians again experimented at Spezia upon thick steel 
plates. 
This time the plates were nearly 28 ins. thick, and were entirely 
cased in 1-in. plate boxes, which dispensed with bolting. They were 
narrow plates, as before (4 ft. 7 in. wide and 9 ft. long), weight about 
20 tons each; but these plates were so utterly destroyed by a single 
round each, from chilled iron or steel projectiles from the 100-ton gun 
firing 550 lbs. of Fossano powder, that the trials had to be discontinued 
without telling much more than was known before. The forged 
steel projectile made by Whitworth seems to have penetrated the 
deepest (21*65 ins.), and remained entire, but it was somewhat set up. 
It is understood that the Italians will continue these trials of armour- 
plates shortly. 
