Submarine Appliances And Their Uses
Deep Sea Diving, &c., &c.

DISPERSING OR BLOWING UP WRECKS. Having ascertained whether the wrecked ship is of wood or iron, a plan of the vessel and its dimensions should be procured, and also a statement of the depth of water in which it lies, and of the nature of the bottom on which it rests (whether rock, sand, gravel or mud) ; in fact, all information available should be obtained as to the wreck, its surroundings and its contents. Wooden Vessels.-—A wooden ship can easily be blown to pieces by a concentrated charge of two or three hundred pounds of Blasting Gelatine or other gelatinous compound, or No. i Dynamite, the quantity required depending upon the size and strength of the wrecked vessel. If dynamite (which in most instances will prove the most effective compound) is used, the charge should be made up in india-rubber cloth bags, containing five to ten pounds each. These should be tightly packed into a strong bag made of sailcloth to protect the waterproof bags from being torn by rough handling on the wreck. One of the india-rubber cloth bags loaded with dynamite should contain the Electric-Detonator Low-Tension Fuse, with electric cable attached for firing the charge. The detonator should be placed in the centre of the explosive, and, to prevent the charge from floating or moving about after it is placed in position on the wreck., it should be, before being lowered, weighted with fragments of old iron chain or other scrap-iron securely tied on the outside. The charge should be carried by the diver through the main hatchway, and placed as far as possible into the hold. The main electric cables should be about 400ft. in length, to allow the operator to get a sufficient and safe distance away when firing the charge. The charge should be lowered to the diver by a rope, and care must be taken that no strain is placed on the electric cable. WHEN ALL IS IN ORDER AND READY FOR FIRING, THE DIVER’S BOAT AND ALL CONCERNED IN CARRYING OUT THE OPERATION SHOULD MOVE OFF TO A SAFE DISTANCE, SAY TWO OR THREE HUNDRED FEET, AND CARE SHOULD BE TAKEN TO WARN OFF ALL BOATS FROM THE VICINITY OF THE wreck. The charge should then be fired by a Twist Exploder, these machines being most suitable on account of portability and certainty of exploding the charge. If Blasting Gelatine, or any of the gelatinous explosives be used, it should be made up into a charge in precisely the same way as described above, except that the priming charge contain- ing the Electric Detonator Fuse should consist of about two or three pounds of dynamite in the middle of the ten-pound waterproof bag of Blasting Gelatine (or other gelatinous compound, as the case may be). This will ensure a complete detonation of the whole charge with greater certainty than if the primer consisted of a gelatinous explosive only. The priming charge must be placed as near the centre or middle of the main charge as possible. On explosion of the charge, the hydraulic pressure stft up inside the wreck will burst it open in all directions. Should any portions of the wreck remain too large to be conveniently handled, they can easily be broken up by a few light charges of explosive of five to ten pounds each. Iron Vessels.—Iron wrecks cannot be broken up in so simple a manner as wooden ones can. Concentrated charges are practically of little use, except in breaking out the stern frame and the bows, as such charges only act locally in blowing holes through the wreck in the immediate vicinity. The best plan for this work is to use long charges of dynamite made up in sailcloth canvas hose or tubing. For the heavy shots, canvas hose j|in. diameter has been found most suitable, and for breaking through the lighter parts of the wreck, hose 2in. diameter is most suitable. The sailcloth canvas to be used for making the hose should be spread out on dry, clean ground or on a floor, and made waterproof by painting it on both sides to saturation with thin india-rubber solution. When dried, it should be dusted over with wood ashes, or some other suitable material, to prevent it sticking together when rolled up. It should then be cut up into suitable lengths and dimensions for making the various-sized tubes, say gft., 15ft. and 22ft. lengths. In sewing these lengths into tube form, after the first 3 or 4in. are sewn, the cartridges must be forced in by hand quite closely in order to completely and tightly fill the tube, and as the sewing proceeds, every 3 or 4m. of the tube must be tightly packed with cartridges, and so on until it is finished, so that when the 106