It has been suggested to use the electric light from the bows of torpedo boats, but this would do away with one of the chief characteristics of such boats, viz. their invisible and unknown approach, on which the whole success of the attack in a great measure depends.
Fosberry's Patent Torpedo Boat Protective.—To enable torpedo vessels and boats to remain afloat after being struck by shot from mitrailleuses, rifles, and other arms usually employed against such craft, and at the same time to retain their structural lightness, Colonel G. V. Fosberry, of the English army, has designed the following method, which is based upon the discovery that when india-rubber or the like is placed and secured on a metal plate, and is penetrated or punctured by a rifle bullet or similar projectile, which also passes through the metal plate, the hole or orifice so formed in the india-rubber will, after the projectile has passed through it and the metal plate, immediately be closed by the elasticity of the surrounding portions, so that no water can follow the projectile through the said hole or orifice. India-rubber or other elastic material, or a combination of such materials, in the form of sheets, belts, or coats, is placed upon or around those portions of the hull of the boat which are to be protected. Vulcanised or mineralised india-rubber is the material usually employed by Colonel Fosberry. Between the metal plates and the india-rubber covering an intermediate substance, generally kamptulicon, is interposed, which is cemented or riveted to the said metal plates, and to which the india-rubber is attached. This intermediate substance, which is the feature of the invention, must be of such a nature that it may be caused to adhere closely and tightly to all parts of the metal, and also to the india-rubber covering, while the same are unperforated, but when the said india-rubber covering and the metal plate under the same are perforated by a bullet, the portion of the said intermediate substance adjacent to the perforation must be detached from the elastic covering and metal plate, and leave the former free to act like a valve, and close up over the hole so that no water may enter; and this intermediate substance, as applied by the inventor in the immediate vicinity of the perforation, will by the effect of the shot be so broken up and detached from the india-rubber covering as to allow the same to recover its original position independently of the new shape or position of the injured and deformed metal plate.
Should the india-rubber be placed upon the metal plates and be so attached to the said plates as to adhere and conform to them in or after their deformation, a hole made in the india-rubber would remain open; on the other hand, should the india-rubber without any intermediate substance be attached to the metal plate in such a manner that it will recover its position after perforation, water would penetrate between the metal and the india-rubber, and by the pressure of this water the india-rubber would be liable to be detached from a large area of the metal plate, and so become ineffective or even dangerous to the boat. Moreover, if the india-rubber is fixed directly upon the metal plates, in the case of a shot passing completely through the boat, that is to say, passing into the boat at one side and out at the other side, a large portion of the india-rubber adjacent to the hole made by the shot in leaving the boat will be torn or destroyed, but this will not be the case in boats constructed according to Colonel Fosberry's patent.
The French government have recently applied this invention to one of their torpedo boats with very successful results, thereby proving that it is not merely a theoretical idea.
Submarine Boats.—Submarine boats, if they could be constructed to fulfil the conditions hereinafter enumerated which are essential to a perfect boat of that nature, would for many reasons be a very important point solved in connection with torpedo operations, and therefore it is most extraordinary that a practicable submarine boat has not yet been designed and built.
Bushnell's Submarine Boat.—The first submarine vessel built for torpedo purposes was designed and constructed by David Bushnell in 1775. This vessel, operated by a Sergeant Esra Lee, was employed in an attempt in 1776 or thereabouts on the Eagle, an English man-of-war, which proved unsuccessful, owing to the sergeant not being thoroughly versed in the management of his curious craft. She was soon afterwards sunk in the Hudson river, but was subsequently recovered by the inventor, though never used again. This vessel was capable of holding one person, and air sufficient to support him thirty minutes without receiving fresh air, and is fully described in 'Barnes's Submarine Warfare.'
Qualifications essential to a Submarine Boat.—A submarine boat should possess the following qualifications:—
1.—It should be of sufficient displacement to carry the machinery necessary for propulsion, and the men and materials for performing the various operations.
2.—It should be of such a form that it may be easily propelled and steered.