Fig. 24 
518 
THE DEVELOPMENT OF ARMOUR. 
States naval authorities. The plate measured 9 ft. by 5 ft. 8 in. by 
6 in. It was backed by 12 in. of oak and two | in. skin plates held 
up by ten bolts. The plate face was hardened to a depth of from 
1*5 in to 2 in. The attack was made with a 6-in. gun firing Carpenter 
steel projectiles, weighing 100 lb. each. The positions of impact on 
the plate are shown in Fig. 24. The data of the four rounds fired are 
shown in the table on page 517 :— 
