THE DEVELOPMENT OF ARMOUR. 
511 
sixth round was fired. It may be seen that the bulging is slight and 
the cracking insignificant. 
Fig. 17. 
Fig 18 shows a plate ll-}-£ in. thick manufactured by the Krupp pro¬ 
cess in the form in which it is worked by Messrs. Vickers which may 
challenge comparison with any thick armour yet tested. The dimen¬ 
sions of the plate were 10 ft. x 7 ft. x 11-j-J in. Three Holtzer 12- 
in. projectiles weighing 721 714, and 715 lbs. struck it with veloci¬ 
ties of 1860, 1868 and 1860 f.s. respectively implying a perforation 
through iron of about 23*5 in. thus establishing a figure of merit of 
Vickers 
lipj-incli. 
plate, 1897 
