168 
MINUTES OF PROCEEDINGS OF 
19. These results were produced at the expense of 1975 lbs. of powder 
for cartridges, and 1150 lbs. in the bursting charges for shells. The amount 
of iron thrown was 15,091 lbs. If account be taken of those projectiles 
which actually struck the parapet and burst, the effect was produced by the 
following expenditure only:—Powder for cartridges, 1162 lbs.; powder for 
bursting charges, 714 lbs.; weight of iron, 9268 lbs, 
20. The breach referred to in Paragraph 18 was almost entirely due to 
the fire of one 110-pr. Armstrong gun on the 4th, and by the expenditure of 
69 rounds; and it was remarked that those projectiles which struck high on 
the superior slope did most execution, cutting away the earth at the point 
struck; those which lodged in the body of the work had not the same effect, 
as the earth was merely raised up, and in some instances into places from 
which it had been previously removed. The fire of the 40-pr., 20-pr., and 
smooth-bore guns, had comparatively very little effect. The craters formed 
were measured after the earth which had been dislodged by the shell had 
been cleared out. In this instance the shell acts as a pick, penetrates a 
certain distance, and then by exploding loosens a quantity of surrounding 
earth, some of which is thrown out of the crater, while some remains in 
it, held together by the sod and grass which covers the natural slope of 
the ground. The rifle shells in general attained about two-thirds of their 
proper penetration before exploding. 
21. The great superiority of rifle over spherical shells was shown; thus 
the mass of earth displaced by the 7 0-pr. rifle shell is about fifteen times as 
much as that by the 68-pr. spherical; while the 40-pr. displaces five times 
as much earth as the 32-pr. The bursting charges are, respectively, 70-pr, 
rifle, 68-pr. smooth, 40-pr. rifle, 32-pr. smooth. 
22. It was found extremely difficult to measure many of the craters of 
individual shells in the artificial earth. A section, however, has been 
prepared, showing the depth and width of a few different craters which were 
noted during the experiments, and a Table gives the other dimensions. 
TABLE 
SHOWING THE DIMENSIONS OE SHELL CEATEES IN AETIEICIAL EAETH. 
General 
No. of 
round. 
Nature 
of gun. 
Sectional 
measurements. 
Diagonals in 
plan. 
Line of 
least re¬ 
sistance. 
Approximate 
cubic 
displacement. 
Hori¬ 
zontal. 
Vertical. 
A. B. 
C. D. 
ft. 
ft. 
ft. 
ft. 
410 
40-pr. 
4-0 
1*6 
8*0 
2*6 
1*6 
413 
40-pr. 
2-6 
2*3 
6*6 
4*6 
2*3 
410 
40-pr. 
4-0 
2*0 
7*0 
7*6 
1*11 
421 
110-pr. 
6*9 
3*0 
9*0 
8*0 
2*9 
422 
110-pr. 
6-0 
4*2 
9*6 
11*0 
3*3 
429 
110-pr. 
7*0 
4*9 
13*6 
5*0 
3*9 
435 
110-pr. 
6*0 
4*1 
11*0 
8*0 
4*1 
466 
70-pr. 
3*0 
3*3 
8*0 
8*3 
3*3 
