Discoveries and Inventions of the Nineteenth Century

sunk with the Housatonic. In general, however, the performance of submarine boats has been unsatisfactory. There is the difficulty of determining accurately the 232course of the boat; there is great danger to the men manning it, as exemplified in the case above; and there is again the problem of providing a means of propulsion which shall enable such a boat to advance or retreat for, say, a mile or more, without making its presence conspicuous by smoke or otherwise. The latter condition would appear to exclude the use of steam for such purposes, as the inevitable smoke and vapour would betray the presence of the wily craft. Another power which has been proposed is air strongly compressed, and recently a still more portable agent has been suggested in solid carbonic acid, which is capable of exerting a pressure of forty atmospheres by passing into the gaseous form. A locomotive form of torpedo, invented by Mr. Whitehead, has the explosive charge, which consists of about 18 lbs. of glyoxyline, placed in the front part of a cigar-shaped vessel, the other part containing mechanism for working a screw-propeller, by means of compressed air contained in a suitable reservoir. This torpedo having been sunk a few feet below the water, the motive power may be set in action by drawing a cord attached to a detent, when the mechanical fish proceeds in a straight line under the water. It is said that this torpedo is effective at 500 yards from the ship attacked, and may even be made sufficiently powerful to travel 1,000 yards under the water. The great objection to such arrangements is the uncertainty of the missile arriving at its destination, for even supposing that the water were without currents, the least deviation from the straight course would cause the torpedo to pass wide of the mark at 1,000 yards distant. It is said that at the experimental trials more than one projector of such war engines has been startled by his machine, after pursuing a circuitous submarine course, exploding in dangerous proximity to the place whence it was sent off, the engineer narrowly escaping 233being “hoist with his own petard.” The experiments which have been made with Whitehead’s torpedo in smooth water appear, however, to have been so far successful that we may probably hear of this invention being put in practical operation in certain cases. Fig. 109 shows the upthrow of water produced by the explosion of one of these torpedoes against an old hulk. The large mass of water thus heaved up is a proof of the mechanical energy of the explosion, and the effect on the hulk is shown in Fig. 110, which exhibits the damage done to her timbers, from the effects of which, it need hardly be said, she immediately sank. In Fig. 112 we have the representation of the explosion of one of Whitehead’s torpedoes containing 67 lbs. of gun-cotton, instead of the glyoxyline. The accurate delineation of these pyramids of water could not have been obtained but by the aid of instantaneous photography, and it constitutes a good example of the great value of such an application of that art, for the instantaneous photographs obtained in these experiments enabled the engineers to calculate accurately the volume and height of the column of water, which thus furnishes a measure of the power of the explosion. Fig. 111.—Experiment made by the Royal Engineers with a Torpedo charged with 10 lbs. of Gun-Cotton. The ordinary torpedo adopted by the British authorities for coast defence consists of a cylinder of boiler plate, 4 ft. long and 3 ft. in diameter. It is intended to contain 432 lbs. of loose gun-cotton, equivalent in explosive energy to about a ton of gunpowder. The effect of one of these torpedoes exploded 37 ft. beneath the surface of the water is depicted in Fig. 113, 234and in Fig. 114 is shown the effect produced when the same charge was exploded at the depth of 27 ft. below the surface. Gun-cotton appears to be the most effective explosive for torpedoes, if we may judge by the large volume of water heaved up, as witness Fig. 111, which shows the result with a small torpedo, containing only 10 lbs. of gun-cotton, exploded at a less depth than those already mentioned. The ordinary torpedoes are moored by an anchor attached to the torpedo, and floating above it is a buoy shaped like an inverted cone. This cone contains a mechanical arrangement of such a nature that when it is struck by a passing vessel, an electric circuit is closed by bringing into contact two wires connecting the torpedo with a voltaic battery on shore. While the apparatus may thus be at any moment made fatal to a hostile vessel touching it, from the control it is under by the engineer having the management of the battery contacts, friendly vessels may pass over it with impunity. Fig. 112.—Explosion of Whitehead’s Torpedo, containing 67 lbs. of Gun-Cotton. The employment of torpedoes develops, as a matter of course, a system of defence against them. Nets spread across a channel will catch drifting torpedoes, and stationary ones may be caused to explode harmlessly by nets attached to spars pushed a great distance forward from the advancing ship. Before the final adoption of Whitehead’s torpedo, presently to be described, the British Government had, after various official trials, approved of a towing torpedo designed for offensive operations. It is the invention of Commander Harvey, and is worthy of a detailed description for the ingenuity of its construction. Fig. 113.—Explosion of 432 lbs. of Gun-Cotton in 37 feet of Water. Fig. 114.—Explosion of 432 lbs. of Gun-Cotton in 27 feet of Water. The shape of Harvey’s torpedo, as may be noticed on reference to Fig. 118, is not symmetrical, but it has some remote resemblance to a boat, though constructed with flat surfaces throughout. The outside case is formed of wood well bound with iron, all the joints being made thoroughly water-tight. The length is 5 ft. and the depth 1¾ ft., while the breadth is only 6 in. Within this wooden case is another water-tight case made of 235thick sheet copper, from the top of which two very short wide tubes pass upwards to what we may term the deck of the wooden case. These are the apertures through which the charge of gunpowder or other explosive material is introduced; and when the tubes have been securely stopped with corks, brass caps are screwed on. The centre of the internal case is occupied by a copper tube, g, Fig. 115, which passes the entire depth, and is soldered to the top and bottom of the copper case, so that the interior of the tube has no communication with the body of the torpedo, the principal charge merely surrounding it. Thus the tube forms a small and quite independent chamber in the midst of the large one, which latter is capable of containing 80 lbs. of gunpowder. The copper tube or priming-case contains also a charge, a, which when exploded bursts the tube, and thus fires the torpedo in its centre. The priming charge is put in from the lower end of the tube, which is afterwards closed by a cork and brass cap, h; 236for the centre of the priming-case is occupied by a brass tube, b, closed at the bottom, but having within a pointed steel pin projecting upwards. In this tube works the exploding bolt c d, which requires a pressure of 30 or 40 lbs. to force it down upon the steel pin. This pressure is communicated to the bolt by the straight lever working in the slot at its head, d, and itself acted on at its extremity by the curved lever to which it is attached. Thus from the mechanical advantage at which the levers act a moderate downward pressure suffices to force the exploding bolt to the bottom of the brass tube. The lower end of this bolt has a cavity containing an exploding composition sufficient in itself to fire the torpedo, even independently of the priming charge contained in the copper tube. This composition is safely retained in the end of the bolt by a metallic capsule, c, which, when the bolt is forced down, is pierced through by the steel pin at the bottom of the brass tube, and then the explosion takes place. The bolts are not liable to explosion by concussion or exposure to moderate heat, and they can be kept for an indefinite period without deterioration. Fig. 115.—Section of Priming-Case and Exploding Bolt. The mode of producing the explosion is not stated: it consists probably of an arrangement for bringing chemicals into contact. Besides the two levers already mentioned, a shorter curved lever working horizontally will be noticed. The object of this is to make a lateral pressure also effective in forcing down the bolt—a result accomplished by attaching to the short arm of the lever a greased cord, which, after passing horizontally through a fairleader, runs through an eye (see Fig. 117) in the straight lever, and has its extremity fastened so that a horizontal movement of the short lever draws the other down. A very important part of the apparatus is the safety key, f, Fig. 115, a wedge which passes through a slot in the exploding bolt, and resting on the brass-work of the priming-case, retains the muzzle 1 in. above the pin. Through the eye of the safety key and round the bolts passes a piece of packthread, e, which being knotted is strong enough to keep the key securely in its place, but weak enough to yield when the strain is put on the line, d´, used for withdrawing the safety key at the proper moment. This line is attached to the eye of the key, and passes through one of the handles forming the termination of the iron straps. As represented in Fig. 117, it forms the centre one of the three coils of rope. The bottom of the torpedo is ballasted with an iron plate, to which several thicknesses of sheet lead can be screwed on as occasion requires. Fig. 117 shows the arrangement of the slings by which the torpedo is attached to the tow-rope, and it will be seen that another rope passes backwards through an eye in the stern to the spindle-shaped object behind the torpedo. This is a buoy, of which two at least are always used, although only 237one is represented in the figure. Each buoy, in length 4½ ft., is made of solid layers of cork built up on an iron tube running through it lengthways, so that the buoys admit of being strung upon the rope. Fig. 116.—Harvey’s Torpedo. Having thus described the construction of the torpedo, we proceed to explain how it is used. It must be understood that if the torpedo and its attached buoys are left stationary in the water, the tow-rope being quite slack, the torpedo will, from its own weight, sink several feet below the surface. But when they are towed, the strain upon the tow-line brings the torpedo to the surface, to dip below it again as often as the tow-line is slackened. There is another peculiarity in the behaviour of the torpedo, and that is that, when towed, it does not follow in the wake of the vessel, but diverges from the ship’s track to the extent of 45°. Its shape and the mode in which it is attached to the tow-line are designed so as to obtain this divergence. But, according as the torpedo is required to diverge to the right or to the left, there must be the corresponding shape and arrangement of tow-line and levers; hence two forms of torpedo are required, the starboard and the port. The figures represent the port torpedo, or that which is launched from the left side of the torpedo-ship, and diverges to the left of its course. The efficiency of the torpedo depends upon the readiness and certainty with which it can be brought into contact with the hostile ship, and this is accomplished by duly arranging the course of the torpedo vessel, and by skilfully regulating the tow-line so as to