58 
ARMOUR AND ITS ATTACK BY ORDNANCE. 
Indian Head 
trials 1891. 
considered in this country by steel makers., but has produced nothing 
hitherto. 1 2 
Competitive armour-plate trials of great importance took place at 
Indian Head, U.S., in November, 1891. 3 The dimensions of the plates 
were the same as at Annapolis, namely, 8 feet x 6 feet x 10*5 inches. 
Six kinds were tested, which are given below in the order of merit in 
which the Board of Officers appointed to conduct the experiments 
unanimously placed them:—(1.) A high carbon nickel steel Harvey- 
Bethlehem plate. (2.) A high carbon nickel steel Bethlehem plate 
(uu-Harveyed). (3.) A high carbon nickel steel plate of Carnegie, 
Phipps and Co. (4.) A low carbon nickel steel Harvey plate of 
Carnegie, Phipps and Co. (5.) A low carbon nickel steel plate of 
Carnegie, Phipps and Co. (6.) A low carbon steel Harvey-Bethlehem 
plate. 
If the order of merit alone be considered, it will be seen that the 
only plate which contained no nickel was the worst in the trial, but 
curiously enough the Harvey process plates standing 1, 4 and 6 are 
rather below the average place. The best plate, however, which was a 
Harvey one, gave such good results that great expectations were enter¬ 
tained as to its future. This process may be said briefly to consist in 
the hardening of the face by carbonizing, and also by the application 
of jets of water. The makers resent the statement that this should be 
termed cementation. They claim that they impart great hardness to the 
surface, and that this hardness extends into the interior of the plate by 
graduation, which they claim is more thorough and sound treatment in 
theory than any attachment of a face plate of hard steel. The trial was 
the same as had been carried out at Annapolis in September, 1890, 3 that 
is to say four rounds were fired near the corners of the plate with 6-inch 
Holtzer forged steel projectiles, each weighing 100 lbs., with a striking 
velocity of 2075 feet, a perforation of 13*2 inches of iron, or 10*6 
inches of steel, and a striking energy of 2086 foot-tons or 318 foot- 
tons per ton of plate supposing the plate to weigh 9‘4 tons. Finally, an 
inch steel Firth Firminy 4 or Carpenter projectile, weighing 210 lbs., was 
fired at the centre with a striking velocity of 1 850 feet, an energy of 
4984 foot-tons, or 540 foot-tons per ton of plate, and a perforation of 
14*7 inches of iron or 1F8 inches, of steel. It may be sufficient to 
notice the behaviour of the best plate, that is the Harvey nickel high 
carbon Bethlehem one. Of this a print (Fig. 8), taken from a photo¬ 
graph by a process in which no hand work is performed, is given 
on p. 59. 
1 The author, in discussing this question in “ Brassey’s Annual ” for 1S90, said, “ The plate 
might thus he saved even from a blow, far outmatching it by breaking up the shot before enough 
energy was delivered to destroy it. In the Redemann»Tilford process the front of the plate is 
said to be rendered hard in an extraordinary degree both by chemical and physical treatment. 
"Whether by this or othei means a plate face may in future be rendered so hard as to break up 
forged steel as at present made, further experiment must show.” 
2 See “ Engineer,” November 20th and December 11th, 1891. 
3 See p. 52. 
4 This is the weight of the Firth Firminy projectile. The Carpenter weighed 250 lbs., and was 
fired with a velocity of 1700 feet. 
