THE HISTORY OE EXPLOSIVE AGENTS. 
375 
all directions to the water (i. e. the existence of a very small vent which permits of an 
escape of water at the instant when explosion was established) sufficed to protect the 
shell against rupture, if the explosion in the latter was not of very sudden nature. 
Thus, on several occasions, 1T2 ounce of fine-grain powder, when exploded by means 
of a fulminate-fuse in a small shell filled with water, failed to burst the latter, the 
water and gases finding their escape through the very small opening in the fuse-plug 
which received the firing wires, and the luting of which did not offer any effectual 
resistance; but even when less than one fourth that quantity (025 ounce=7‘8 grms.) 
of gun-cotton was detonated under the same conditions in shells of the same size, no 
instance occurred in which the shell escaped being broken into a large number of 
pieces, the suddenness with which the force was developed and transmitted by the 
water leaving no time for the small vent to exert any decisive influence upon the 
results. 
It should be stated that the disintegration of the shells by 1 ounce, and even ^ ounce 
of gun-cotton, through the agency of water (as shown in Table III.), is far too complete 
to be of practical value, as the large number of very small fragments produced would 
be of no use as missiles. The fragments furnished by employing only 025 ounce of 
gun-cotton in the particular sizes of shells used were of much more serviceable nature. 
Even with this very small charge the shells were not merely burst into very numerous 
fragments, but these were also projected with considerable force. 
The powerful effects obtained in those shell-experiments in which gun-cotton was 
employed, and the fact that detonation was transmitted from one mass of compressed 
gun-cotton to another through small water-spaces under the conditions described at 
page 372, led me to attempt the transmission of detonation from one mass of gun- 
cotton or dynamite to another in a tube, with the intervention of water. The tubes 
(of wrought iron, T25 and 1 inch in diameter) were fixed in a vertical position ; the 
lower extremities were closed with plugs of wood and of clay, and in some instances 
with strong metal screw-caps ; the gun-cotton or dynamite was placed at this extremity, 
and the initiative charge, consisting of 2 ounces of compressed gun-cotton or of dyna- 
mite, enclosed in waterproof material, was just immersed in the water at the upper 
extremity and was detonated in that position. The distance between the two charges 
of explosive material was reduced to 2 feet without detonation being transmitted ; and 
it was evident that, under the conditions fulfilled by these experiments, the intervening 
column of water, even if much reduced in length, must act as a protective to the sub- 
merged explosive charge, the force being mainly expended in the opposite direction, 
where comparatively little resistance was opposed to it. 
Other experiments, to which I was led by the remarkable effects produced in deto- 
nating small charges of gun-cotton in shells filled with water, furnished interesting and 
important results. In developing detonation in a perfectly closed and sufficiently strong- 
vessel, which is completely filled with water (in addition to the small detonative charge), 
the resistance offered by the water, at the instant of detonation, may be regarded as 
