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

canvas tube is completed, and the ends sewn up, it must present a solid cable or rope-like appearance, with no slack places in it. A ready-made canvas tube cannot be packed with cartridges so solid as when the cartridges are packed in whilst the tube is sewn up and made as above indicated, and it is necessary that the canvas tube be made up and charged as de- scribed, so that the cartridges shall lie together solidly and compactly, with no air space between them. To insure perfect detonation throughout these long lengths of hose charges, if the explosive used is Blasting Gelatine (or other gelatinous explosive of a like nature), the centre cartridge or core should consist of dynamite throughout the whole length, so as to form a detonating core, and thus insure complete detonation. In commencing operations on a wreck, the diver should go clown and explore the upper deck as far as practicable, and report what length of the deck is fairly clear for laying’ charges upon. This is then noted on the plan of the wreck in the possession of the operator. If the diver reports that he can get a charge of 50ft. or 60ft. in length placed on the deck along- side the bulwarks on one or both sides of the deck, this long length of charge is made up of various pieces of canvas tube containing explosive, joined together by overlapping joints—that is, the ends overlap 6in., and are tied firmly together by strong string so that they cannot break apart. The full length of canvas tube is then weighted at intervals of ift. to 2ft. apart, with pieces of 6in. to a foot of old iron chain (say Jin. or |in. chain), and with fragments of old iron, such as bolts, nuts, etc., to keep the charge in position and in close contact with the wreck. The chain and iron fragments should be tied on firmly and tidily with strong string, so that nothing is left to chance. The end of the canvas tube, in which the Electric Detonator Fuse is fixed, should have a piece of strong marline tied around it with qft. or 6ft. of loose ends, free to enable the diver to tie the charge firmly to some convenient part of the wreck to prevent the charge being shifted by any strain from the Electric Cable. A charge 60ft. to 70ft. long, containing 120 lb. or more of Dynamite, is readily disposable in the way described. The explosion of a suitable charge, prepared as above and properly placed, will cut through the deck and break off all the beams and stays through the whole length of the charge, besides bulging out the side of the vessel, and breaking and releasing all woodwork in the vicinity. After each shot the diver must descend and explore the wreck for other clear spaces for laying down fresh charges, the main object being to get the charges placed along the sides on the deck close to the bulwarks, so as to break off the iron beams and stays support- ing the deck, and to bulge out the sides. When very powerful beams require to be broken, it may be necessary to employ extra quantities of explosive. At intervals of, say, 30ft. or 40ft. apart, or wherever practicable, a canvas tube charge of 10ft. or 12ft. in length should be hung over the side and fired, which will cut a gash through the hull plates. The wreck will then be found to bulge out and flatten down considerably. In the event of its being impracticable for the diver to get about in the wreck after the first few shots are fired, it will probably be found more convenient to operate from the outside by laying long canvas hose charges alongside in contact with the wreck along the bottom. On being fired these will cut through the hull, and bring about a general breaking up of the wreck. Occasional local charges will probably have to be used for blowing away the stern frame and opening out the bows, and also for removing any other local obstruc- tions which the long- shots may have been too far away from to break. Such local shots are best made up in sailcloth canvas bags about 3ft. long by yin. in diameter, which will contain about fifty pounds of Dynamite. For cutting off masts, a canvas hose charge tied completely round the mast as low down as possible will, on exploding, completely sever it. In breaking up a wreck, if the foregoing method be properly carried out, with the neces- sary modifications to suit varying conditions (which modifications the common sense, know- ledge, and experience of the operator will suggest), the result will be found to be entirely satisfactory. Note.—When the first shot is fired on a wreck, many fish are generally brought to the surface, those that were nearest to the charge being killed outright, whilst others are stunned and struggle on the surface; the latter will recover from the shock if not soon captured. The fish in the locality soon get educated up to shot-firing, and give the wreck a wide berth. J07