THE DEVELOPMENT OF ARMOUR. 
513 
The plate was a Bethlehem one, 10 in. thick, and was attacked in the 
spring of 1897 by 8-in. Holtzer shot weighing 250 lbs., with striking 
velocities of 1,474, 1,754, and 2,079 ft.-secs., the striking energy of the 
last round being 7,494 ft.-tons. These velocities imply perforations 
through iron of 12, 15*6 and 20*1 in., the last being 2 01 times the 
thickness of the plate. The penetrations effected were estimated at 
2, 4, and 10 in. The plate is apparently excellent, but the severity of 
the trial cannot be compared with that of the Vickers llh^-in. plate 
Fig. 19. 
because although the perforation test by the last round is nearly the 
same, the two first, which, it appears, would have secured the accept¬ 
ance of the plate, were much lighter blows, whereas Vickers plate re¬ 
ceived three similarly heavy blows. The American 10-in. plate was 
attacked by an 8-in. shot, and the Vickers HyJ in. by a 12-in shot. 
Without being able to give the exact weight of the plate, it may 
be seen from the scale in the figure that its dimensions were about 
12 ft. x 6ft. 6 in., so its weight would be about 14*3 tons, and 
the shock per ton of the heaviest blow only about 524 ft.-tons 
as compared with 1,169 ft.-tons in the British plate. Then again, 
the penetration actually achieved was much greater in the American 
plate. Lastly, the scale of operations is smaller, which favours 
the plate generally. Altogether, remarkable as the achievements 
of U.S. armour have been, there has been nothing in thick Harveyed 
