THE HISTORY OF EXPLOSIVE AGENTS. 
373 
either by the resistance which the material of the case offers in which the gun-cotton 
disks are confined, or by the pressure of a considerable column of water, the detonation 
of wet compressed gun-cotton, immersed in water and separated from the initiative 
detonator and surrounding masses by thin layers of the liquid, can be accomplished 
with certainty. Results fully equal to those obtained with wet charges enclosed in 
stout metal cases have been furnished by charges closely packed together and confined 
round the initiative detonator by means of a case of thin sheet-tin, or a bag, or even by 
a simple fishing-net (being thus freely exposed to the surrounding water), provided they 
are immersed in water to a considerable depth. Charges of wet gun-cotton arranged 
similar to these, but in which the individual masses were not firmly enough held toge- 
ther, thus allowing of greater water-spaces between them here and there, and greater 
liability to movement, or which were submerged to comparatively small depths, failed 
to be detonated, even when comparatively large initiative charges of dry gun-cotton 
were employed, the wet disks being simply dispersed by the explosion. 
The suddenness and completeness with which detonation was transmitted through 
small water-spaces, in the experiments with iron cases, suggested to my mind the possi- 
bility of applying water as a vehicle for the efficient employment of small detonating 
charges for bursting or breaking up cast-iron shells into numerous, and comparatively 
uniform, fragments, thus applying a shell or hollow projectile, of the most simple con- 
struction, to fulfil the functions of the comparatively complicated shrapnel or segment 
shells. The results furnished by experiments in this direction are interesting, and may 
prove of practical importance ; they are fairly represented by the examples given in 
Table III. (p. 374). The shells experimented with were exploded by electric agency, 
being placed in a capacious iron chamber, or cell, lined with oak, specially constructed 
to admit of the collection of fragments of shells after their explosion. The charge of 
explosive material, fitted with the fulminate-fuse by which it was detonated, was either 
enclosed in a cylinder of thin sheet-iron or (in the case of gun-cotton charges) simply 
coated with waterproofing material ; it was attached to the screw-plug of the shell, so 
that, when this was inserted and screwed into its place, the bursting-charge was fixed 
in the centre of the shell, being surrounded in the latter on all sides either by air or 
water. The fine wires by which the detonating fuse was fired were passed through a 
small' opening in the screw-plug, which was then filled up with cement, so that the 
shell, when fitted, was closed as securely as possible. In subsequent experiments, in 
which the shells were fired from guns, the bursting-charges were fitted to the base of 
the concussion-fuse used in the service, so that the shells were absolutely closed when 
the fuse and charge were screwed into position. 
These results afford interesting demonstration of the power possessed by water to 
transmit, uniformly in all directions, the force developed by an explosion, the destruc- 
tive effect being proportionate not merely to the amount of explosive agent used, but 
also to the suddenness of the concussion imparted to the water by the explosion. They 
showed, besides, that a very slight flaw in the continuity of the resistance opposed in 
