66 
POPULAR SCIENCE 
REVIEW. 
December 10, 1875. 
Charge. 
Description of 
Initial velocity. 
Pressure on gun. 
Round. 
lbs. 
Pebble Powder. 
Feet per second. 
Tons per sq. inch. 
f 1 
220 
1*5 inch cubes 
1,440 
28-1 
\ 2 
220 
1*7 „ „ 
1,414 
25-1 
220 
» J) 
1,366 
24*4 
4 
250 
2*0 „ „ 
1,523 
24*8 
Rounds 1, 2, 3 of December 10 gave exceptional results, as 
they were fired with a projectile of 1,460 lbs. and consequently 
the velocities obtained were much lower and the pressures pro- 
portionally higher than with the smaller projectile ordinarily 
employed. It will be observed that pressure and velocity in- 
creased with the weight of the charge, but decreased as the size 
of the pebbles was augmented, the pressure, however, decreasing 
in a much greater ratio than the velocity. Thus the action of 
the charge is completely under control. 
It has been assumed that it will be well to keep the pressure 
of the gas in the powder-chamber below 25 tons per square 
inch ; and these experiments show that this can be easily 
accomplished, while at the same time giving a very high initial 
velocity to the shot. When the gun is bored out to its full 
calibre, it will probably give even more striking results. 
Mounted on the ordinary carriages and slides, and worked by 
manual labour, these huge guns would be almost unmanage- 
able, and at best would deliver only a slow inefficient fire. But 
all difficulties in the way of using them with good effect have 
been removed by an invention of Mr. Rendel, of the Elswick 
Works, which will make these monster pieces of artillery more 
handy than even the old 68-pounders. 
The leading features of the arrangement are shown in fig. 3. 
Two guns will be mounted side by side in each turret. Each 
gun will be mounted so as to be supported on three points. 
The trunnions will rest on blocks sliding on fixed beams bolted 
down to the floor of the turret, while the breech will rest on a 
third block, sliding like the others between guides, upon a beam 
or table. Behind each of the trunnion-blocks, in the line of 
recoil, are two hydraulic cylinders, connected with them 
by piston-rods. The cylinders communicate by a pipe, on 
which there is* a valve, that on the recoil of the gun opens and 
allows the pistons of the rams to run back slowly, checking the 
recoil. By reversing the apparatus, the gun can be run out 
again. The beam on which the breech rests is supported by a 
third hydraulic ram, fixed vertically beneath it in the turret. 
By this means the breech can be easily raised or lowered, thus 
elevating or depressing the muzzle of the gun, which pivots on 
its trunnions with a large preponderance towards the breech. 
