THE “INFLEXIBLE AND HER ARMAMENT. 
65 
its projectile, and there is little doubt that at 1,000 yards it 
would penetrate 20 in. or even 24 in. of armour. At 250 feet 
the flat-headed bolts used in the experiments were buried 50 ft. 
in the sandy butt at the end of the proof-ground. The expe- 
riments have shown, too, that the action of the pebble powder is 
perfectly under control ; that by using the various sizes a greater 
or less velocity can be given to the shot, a greater or less strain 
brought to bear upon the gun. By means of Major Maitland’s 
gas-check all windage is stopped, and thus none of the force of 
the powder is wasted, and the bore and rifling of the gun is 
saved from erosion by the gas escaping round the shot, which 
wears out muzzle-loading guns more rapidly than any other 
agency. Maitland’s gas-check consists of a plate of copper with 
a heavy rim attached to the base of the shot. On firing the 
charge the soft copper is forced into the grooves, and stops the 
windage. This gas-check is now in use throughout the whole 
of our heavy artillery. The flat-headed projectiles used in the 
trials of the 80-ton gun weighed, including the gas-check, 
about 1,260 lbs. The powder used in the charges was the large 
cubical pebble powder described in the Popular Science Review 
in January last.* The following table shows the velocities 
and maximum pressures in the powder chamber on each 
occasion : — 
September 
17, 
£ 
00 
r— 1 
Charge. 
Description of 
Initial velocity. 
Pressure on gun. 
Round. 
lbs. 
Pebble Powder. 
Peet per second. 
Tons per sq. inch. 
1 
170 
1*5 inch cubes 
1,393 
24*2 
2 
190 
1-5 
a 
if 
1,423 
22*3 
3 
210 
1-5 
a 
fi 
1,475 
24*8 
4 
220 
1-5 
ff 
if 
1,503 
22*2 
5 
230 
1*5 
ff 
if 
1,550 
29*6 
6 
240 
1-5 
u 
if 
1,551 
27*3 
November 
16. 
1875. 
1 
220 
1*5 inch cube3 
1,525 
25*8 
2 
220 
1-7 
r> 
a 
1,420 
206 
3 
230 
1*7 
ff 
a 
1,454 
20*2 
4 
240 
1*7 
if 
a 
1,470 
21*0 
December 
9, 1875. 
1 
220 
1.5 inch cubes 
1,535 
24-1 
2 
220 
1-7 
if 
a 
1,502 
23*0 
3 
220 
2-0 
a 
a 
1,485 
21-7 
4 
230 
1-7 
a 
a 
1,543 
24-9 
5 
230 
2-0 
a 
if 
1,498 
23-4 
6 
240 
2-0 
if 
a 
1,513 
230 
* Article, “Gunpowder, its Manufacture and Conveyance.” By A. 
Hilliard Atteridge. January, 1875. 
VOL. XV. — NO. LVIII. E 
