There is another system which is likewise in use in the French navy, and that is the Whitehead torpedo. This consists of a metallic cylinder, tapering at each end, and containing not only a charge of gun cotton, but a compressed air engine which actuates two helices. It is, in fact, a small submarine vessel, which moves of itself in the direction toward which it has been launched, and at a depth that has been regulated beforehand by a special apparatus which is a secret with the inventor. The torpedo is placed in a tube situated in the fore part of the torpedo boat, and whence it is driven out by means of compressed air. Once fired, it makes its way under the surface to the spot where the shock of its point is to bring about an explosion, and the torpedo boat is thus enabled to operate at a distance and avoid the dangers of an immediate contact with the enemy. Unfortunately this advantage is offset by grave drawbacks; for, in the first place, each of the Whitehead torpedoes costs about ten thousand francs, without counting the expense of obtaining the right to use the patent, and, in the second place, its action is very uncertain, since currents very readily change its direction. However this may be, the inventor has realized a considerable sum by the sale of his secret to the different maritime powers, most of whom have adopted his system.
All our ports are provided with flotillas and torpedo boats, and with schools in which the officers and men charged with this service are trained by frequent exercises. It was near L'Orient, at Port Louis, that we were permitted to be witnesses of these maneuvers, and where we saw the torpedo boats that were lying in ambush behind Rohellan Isle glide between the rocks, all of which appeared familiar to them, and start out seaward at the first signal. It was here, too, that we were witnesses of the sham attack against a pleasure yacht, shown in one of our engravings. A torpedo boat, driven at full speed, stopped at one meter from the said yacht with a precision that denoted an oft-repeated study.
MODE OF FIRING TORPEDOES.
Before we close, we must mention some very recent experiments that have been made with a torpedo analogous to Whitehead's, that is to say, one that runs alone by means of helices actuated by compressed air, but having the great advantage that it can be steered at a distance from the very place whence it has been launched. This extraordinary result is obtained by the use of a rudder actuated by an electric current which is transmitted by a small metallic cable wound up in the interior of the torpedo, and paying out behind as the torpedo moves forward on its mission. The operator, stationed at the starting point, is obliged to follow the torpedo's course with his eyes in order to direct it during its submarine voyage. For this reason the torpedo carries a vertical mast, that projects above the surface, and at the top of which is placed a lantern, whose light is thrown astern but is invisible from the front, that is, from the direction of the enemy. A trial of this ingenious invention was made a few weeks ago on the Bosphorus, with complete success, as it appears. From the shore where the torpedo was put into the water, the weapon was steered with sufficient accuracy to cause it to pass, at a distance of two kilometers, between two vessels placed in observation at a distance apart of ten meters. After this, it was made to turn about so as to come back to its starting point. What makes this result the more remarkable is that the waters of the Bosphorus are disturbed by powerful currents that run in different directions, according to the place.--L'Illustration.
PICTET'S HIGH SPEED BOAT.
It is now nearly a year ago since we announced to our readers the researches that had been undertaken by the learned physicist, Raoul Pictet, in order to demonstrate theoretically and practically the forms that are required for a fast-sailing vessel, and since we pointed out how great an interest is connected with the question, while at the same time promising to revert to the subject at some opportune moment. We shall now keep our promise by making known a work that Mr. Pictet has just published in the Archives Physiques et Naturelles, of Geneva, in which he gives the first results of his labors, and which we shall analyze rapidly, neglecting in doing so the somewhat dry mathematical part of the article.
For a given tonnage and identical tractive stresses, the greater or less sharpness of the fore and aft part of the keel allows boats to attain different speeds, the sharper lines corresponding to the highest speeds, but, in practice, considerably diminishing the weight of freight capable of being carried by the boat.