ARMOUR AND ITS ATTACK BY ORDNANCE. 
63 
Fig. 11. 
248*5 foot-tons per ton of plate, if it weighed as re¬ 
ported, 13,110 kg. or 12*9 tons, but this implies some 
mistake, as a steel plate of the dimensions given would 
weigh under eight tons; probably the width is wrongly 
stated. There was very little cracking. The plate, 
therefore, was very tough, but not very hard. 
The second plate 8*25 feet x 8*27 feet x 9*84 inches 
was attacked by an old type gun of 9*4 inches (2i cm ) 
calibre. Three chilled-iron projectiles were fired at it, 
each weighing 31 7*5 lbs., with a striking velocity of 
1343 feet, and a calculated perforation of 11*8 inches 
of iron or 9*4 inches of steel. The plate was 9*84 
inches thick so that complete perforation even with 
steel was hardly to be expected. The severity of the 
test was the tearing or wedging action. The striking 
energy was 3972 foot-tons or 330 foot-tons per ton of 
plate, supposing the latter to weigh, as reported, 
12,395 kg. or 12*2 tons. The chilled projectiles natur¬ 
ally broke up, but they broke up the plate, which 
seems to imply that chilled projectiles which would 
sputter harmlessly against plates with a hard face, are 
formidable to comparatively soft though tough nickel 
steel. Against broken portions of this plate steel pro¬ 
jectiles (two 24 cm and one 16 cm steel projectiles), after¬ 
wards rebounded. 
As regards nickel steel, deck plates of this material 
have been made by Cammell and supplied to nearly all 
the vessels of the Rawilles class, and many trials have 
been made with nickel vertical steel plates in England. 
In spite of some marked success, certainty as to 
quality had not as yet been ensured. 
In May, 1892, 1 2 a nickel sample steel plate 10 
feet x 6 feet X 14 inches (see Fig. 12), representing 
about 250 tons, for diagonal bulkheads of the U.S. 
battle-ships, Massachusetts and Indiana , was tested at 
Indian Head by a 10-inch gun firing three projectiles 
(presumably of forged steel), each weighing 500 lbs ; 
the striking velocity was 1400 feet, and the perforation, 
calculated on the English system, 15 inches of iron 
or 12 inches of steel; perforation, therefore, was not 
to be expected, and it appears that there was no 
appearance of the points at the back 3 and a total 
absence of cracking. The plate probably weighed about 15*4 tons. 
The striking energy of each round was 6795 foot-tons, or 441*7 foot- 
tons per ton of plate. The Nettle trials give only 300 foot-tons per 
ton of plate. It may be seen then that this plate bore the shock or 
1 See “ Engineer ” of July 15th, 1*92; 
2 This means no doubt no appearance of star openings made by the points. The projectiles 
appear to have rebounded, 
Nickel 
deck plates. 
Nickel steel 
plates in 
America 
189J. 
