TOEPEDOES. 
175 
the great resistance encountered in the interior of the vessel. 
The machinery, however, showed symptoms of having been 
shaken, and some beams were cracked. A charge of 230 lbs. 
of compressed gun-cotton was placed in the same position and 
fired, and it appeared entirely to complete the demolition. 
The engines, weighing 300 tons, were shifted bodily out of 
place ; the boilers also were moved, and the wreck was so 
shattered as to permit of its being pulled up. . . . The work 
done by the cotton was estimated to be equal to that which 
would have been done with 1,000 lbs. of gunpowder.”* Ex- 
periments made at Chatham prove that, under water, a charge 
of gun-cotton will (as in the instance we have just given) pro- 
duce the same effect as four times its weight of gunpowder. 
This supposes that in both cases the object aimed at is ver- 
tically, or almost vertically, abov^ the charge. But it is found 
that the proportion is different with regard to the lateral or 
horizontal range of the two explosives. The conclusion drawn 
from another series of experiments, directed to determine the 
point, was that charges of gun-cotton and gunpowder, in the 
proportion of 2 and 5, would give equal radii of destructive 
effect ; but within the radius, the gun-cotton would do the 
greater damage of the two. All these facts point to one con- 
clusion — that gun-cotton is by far the best explosive for tor- 
pedo service. Its advantages are — (1) it can be safely 
stored ; (2) it requires only a [light watertight case ; (3) its 
explosive power is to that of gunpowder as 4 to 1 ; (4) it has, 
weight for weight, a greater radius of destructive effect. Gun- 
cotton has therefore been generally adopted for torpedo work, 
and, as we have mentioned before, it was the substance used by 
the Austrians in 1866. 
As for the other explosives, there are none of them which 
show any superiority to gun-cotton, and none of them are 
equally safe. One, indeed, nitro-glycerine, possesses the great 
advantage of not being injured by water ; so that, if it were 
used for torpedoes, the cases need not be so perfectly water- 
tight. But this is compensated by a correspondingly great 
defect — it is very dangerous to use; and the reader will 
readily call to mind more than one fatal explosion, the result 
of some slight accident in its employment or transport. 
As to the proper amount of the charge, different writers give 
various estimates. It will depend on several considerations — 
the nature of the explosive, the size and build of the ships 
against which it will probably be used, the depth at which the 
torpedo is placed, and, finally, the nature of the bottom. It 
is found that on a soft muddy bottom the downward force of 
* Journal of the Eoyal United Service Institution,” vol. xiv. p. 444. 
