THE ROYAL ARTILLERY INSTITUTION. 
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its power and effects together with those of common shell; the main 
feature to notice in both cases being the very great explosive power, 
especially great when compared with smooth-bore shell, which always 
were under the weight that would seem to belong to their name. 
To give some comparison. The 13" shell contained nearly 11 lbs., 
while the Woolwich 12" shell will take 35 lbs.; the 68-pr., or 8" shell, 
has a bursting charge of 2 lbs. 9 ozs., and the 7" rifled shell 8J lbs. of 
powder. 
The exact effects of these shells in bursting has never been thoroughly 
investigated; but Admiral Key, on February 2nd, 1866, reports on 7" 
double shell fired at the “ America” to test its effects. One burst 6 ft. 
inboard the lower deck, entirely destroying one-half of a main-deck 
beam, with about 8 ft. square of planking, and cutting severely into 
the planks and beams of the lower deck. Another struck the chain 
cable on starboard quarter, and burst before passing through, making 
a clear hole inside about 26 ins. square, and laying eight planks on the 
side open to the extent of 28 ft. by 8 ft.; the damage in this case was 
very close to the water-line. These shells have been fired up to more 
than 2000 yds., the committee report, with satisfactory accuracy. 
Such being the power of 12Jibs, of powder, what may we expect 
from 35 lbs. ? To this I cannot give an answer; for I know of no 
experiments to quote, either as to breaching of masonry, earth, or the 
destruction of ships 5 sides. 
Next, as to incendiary power—although targets and backings are 
sometimes ignited with the double shell—Admiral Key remarks:— 
“ In no instance did they set the ships on fire. 55 This being so, I may 
call attention to the fact that, though a comparatively recent order 
extended the application of carcasses to all calibres of smooth-bore 
guns down to the 12-pr., there exists no kind of incendiary projectile 
for rifled ordnance of any calibre; which is the more remarkable, 
because, for obvious reasons, as to studs, coats, &c., red hot projectiles 
could not be fired; and further, carcass rockets have ceased to exist, 
and even shell rockets have been made into shot by having the head 
plugged up with wood. 
There is a curious fact connected with the strain on a shell in the 
bore of the gun that I should notice—viz. the great pressure of the 
gas escaping past the shell, on its sides. The specimen on the table is 
a comparatively mild example of the effects of this. It will be seen 
that in that shell the diameter in the middle is only 8*55 ins., while that 
at the base is 8*92 ins., and close to the head 8*9 ins.; this is due to the 
pressure of the gas in the gun having told more on the part of the shell 
furthest from the support afforded by the metal at the head and base. 
I need hardly say before firing, the shell was of one diameter throughout; 
from this the value of the longitudinal flanges or ribs in the interior of 
the double shell may be seen. I may also call attention to the curious 
nature of the action of the flash of exploded gas firing a shell by entering 
at a porous place through a tortuous hole. I believe some remarkable 
results might be quoted by officers who have experimented as to this at 
Shoeburyness, but I would only notice the singular conditions of the 
question. You have gas at a great heat forced through a mass of metal 
