THE ROYAL ARTILLERY INSTITUTION. 
5 
Nos. 4 and 5, weighing together 9'08lbs. per square foot, were placed 
upright, in a line, leaning against a stand on the ground; two shots were 
fired at them ; both passed through them. 
No. 5, weighing 4*97 lbs. per square foot, was placed behind No. 4, 
leaving an interval of about an inch; five shots were fired at them, four of 
which passed through first and slightly dinted second, and one passed through 
first and broke second at the top of plate. 
No. 4, weighing 4*11 lbs. per square foot, was then placed in front of 
No. 5 ; five shots were fired at them, four of which passed through first and 
lodged in second. 
No. 5, weighing 4*97 lbs. per square foot, was then placed in front of 
No. 4, 4>\ ft. apart, both mantlets leaning against a stand; five shots were 
fired at them; all passed through first and slightly dinted second. 
No. 9, weighing 4*44 lbs. per square foot, was then placed in front of 
No. 10, 4^ft. apart, leaning against a stand; two shots were fired at them; 
both passed through first and dinted second. 
No. 10, weighing 3*41 lbs. per square foot, was placed in front of No. 9, 
41 ft. apart, leaning against a stand; one shot was fired at them, which passed 
through first and lodged in second. 
No. 9 was taken away, and two more shots were fired at No. 10, one of 
which passed through it, and hit the target very hard; the other passed 
through the plate and penetrated the leg of wooden stand. 
8. The result shewed a decided superiority of the annealed steel over the 
tempered steel, and gave encouragement to the principle of construction 
adopted. 
Captain Yonge then submitted a mantlet composed of two -tthinch plates 
of homogeneous iron secured by bolts and nuts, with a space of 1J in. 
between them. The weight was 13 lbs. per square foot. It was fired at 
July 6th, and proved perfectly bullet-proof at 10 yds. The bullets passed 
through the first plate and slightly indented the second, but did not in any 
case fracture or penetrate it. 
The experiment was repeated July 13th, with interval of the plates 
reduced to J in., with the same results as to non-penetration of the second 
plate, but it was much more deeply indented by the bullets which penetrated 
the first plate. 
The experiment was repeated in October, with a mantlet weighing 10 J lbs. 
per square foot, and composed of thinner plates, viz. one of -^g-th inch, the 
other rather more than -i-thinch (about 0*14 in.), they were restored to the 
original interval of 1J inch, and proved perfectly shot-proof at 10 yds. 
9. The foregoing trials having sufficiently established the resisting 
powers of the several materials referred to, the Committee took steps to 
ascertain their behaviour when struck by cannon shot. 
With this view the in. homogeneous iron mantlet of 4 ft. by 2J ft., 
submitted by Captain Yonge, No. 23 of the accompanying list, another 
mantlet, No. 2, of Thorneycroft’s steel iron, and one of Captain Yonge's 
double mantlets, No. 26 in the general list, were fired at with segment 
shells from an Armstrong 12-pr., at 400 yds., and solid shot from a smooth- 
