3-034-773 - The Print Collector/Heritage Images

Chatham Siege Operations: explosion of mines under the Medway, 1871. British Army training. 'The six or seven mines laid under water, across the river Medway, from Gillingham Hard, to be exploded in succession by electric sparks from the instruction-ship Volta, produced a great sensation. Each of these mines was charged with 50 lb. of gun-cotton, placed in an indiarubber bag sealed with glue. The submarine mines used in real warfare would probably be of 500 lb., in metal cases. Each bag of gun-cotton was furnished with a fuse, consisting of a platinum wire surrounded with fulminate of mercury. The wire communicated with that of an electric telegraph cable, which was laid to the Volta, whence the electric spark could be discharged by simply thrusting a little peg into a hole upon a board. In the view shown by our Engraving four of the mines, extending across from the right bank of the river, seem to have gone off, and two yet remain to be fired'. From "Illustrated London News", 1871.