52 
ARMOUR AND ITS ATTACK BY ORDNANCE. 
Annapolis 
Competition 
1890. 
allowed to exhibit their own plates, and photographs of them were 
shown in the Institution of Civil Engineers in the autumn of 1889, 
when Messrs. Cammell exhibited a compound and an " all steel” plate 
and Messrs. Vickers one of "all steel,” which had been specially suc¬ 
cessful. The elements of this series of trials remained unaltered for 
^ears, being continued as reception tests. These were the following. 
The plates* dimensions are 8 feet x 6 feet x 10*5 inches ; weight 
from 9 tons 7 cwt. to 9 tons 9 cwt. The attack was made by a 6-inch 
gun, firing three forged steel projectiles, supplied by TIoltzer, and two 
chilled iron shot, the weight of each being 100 lbs. The striking 
velocity was 1976 feet, the energy 2708 foot-tons, and the calculated 
perforation 12*6 inches of wrought-iron, or 10 inches of steel or steel¬ 
faced armour. The shock per ton of plate was about 288 foot-tons. 
At this time, 1889, the points of the steel projectiles got far enough 
to tear open the backs of the best plates in small star cracks, but not 
to be themselves visible. 1 The chilled shot broke up with much less 
effect. On May 1st, 1890, Cammell submitted a plate against which 
the Holtzer projectiles began to break up. 
In the autumn of 1890, a competitive trial of plates took place at 
Annapolis, U.S., on September 18th and September 23rd. The 
plates were 8 feet X 6 feet x 10'5 inches,-and weighed about 9*4 tons. 
Two were supplied by Schneider—one of steel, hammered and made 
on his usual system, and one differing in the fact that it contained 5 
per cent, of nickel. One plate was submitted by Cammell, of the 
usual Wilson steel-faced make. On September 18th four Holtzer 
forged steel projectiles were fired at each plate from a 6-inch gun. 
Each shot weighed about 100 lbs. The striking velocity was 2075 f.s., 
giving a calculated perforation of 13'2 inches of iron or 106 inches of 
steel, and a total energy of 2986 foot-tons, and an energy per ton of 
plate of 318 foot-tons. These four rounds were fired towards the cor¬ 
ners of the plates, as shown in the Figs. 1, 2, and 3, pp. 53, 54. On 
September 23rd, one round was fired from an 8-incli gun at the centre 
of each plate, with a forged steel projectile, which, being' more than a 
match for the plates, perforated in each instance. The hardest plate 
would suffer the most from this round, as it would transmit more of 
the shock into the surrounding mass of plate before it let the shot 
through. Unless the velocity of the shot were taken after its passage, 
it would not be possible to tell how far the plate had resisted the shot. 
It may be seen in Fig. 5 that Schneider's nickel plate exhibits no frac¬ 
ture. The 8-inch projectile penetrated 10J inches into the backing* of 
this plate, but the 6-inch projectiles were all stopped with the points 
just seen at the back of the plate. The Schneider ordinary steel plate 
(Fig. 4) is broken across through the five shot holes in an X shaped 
crack. On the other hand, it stopped the projectiles with less pene¬ 
tration than either of the other plates. The Cammell-Wilson compound 
plate allowed of most easy penetration, the 8-inch shot passing entirely 
through three feet of backing into the mound behind. It had no 
1 Figures of these plates were given in “ Brassey’s Annual” of 1889. They possessed an 
interest then that was lost when they were surpassed by other plates in the results obtained under 
the same trial. 
