TORPEDOES. The torpedoes known to modern warfare are all automobile; that is to say, they run by their own power, differing in this respect from pro jectiles fired from guns, which otherwise they rather closely resemble. And not only do they run by their own power, but they carry a complicated mechanism by which they steer themselves, regulate the depth at which they run, and render themselves harmless after a certain length of time if they fail to hit their mark.
Torpedoes of various forms have been known and used for several centuries, but the automobile torpedo of today is essentially a development of the last fifty years, having been invented about 1870 by an Englishman, Whitehead, who, fail ing to secure recognition from the British naval authorities, took his invention to Austria, where it was at once adopted. It was slow in making its way in other countries, and even as late as the begin ning of the World War, in 1914, was regarded in many quarters as of no great practical value. It accomplished nothing in the Spanish-American War of 1898 and little or nothing in the Russo-Japa nese War of 1904; and even those who had most faith in its possibilities were unprepared for the manifestation of its efficiency given by the Germans in the first months of the World War and there after. A large part of this efficiency was due, of course, to the remarkable development of the submarine, a develop ment which at that time had been car ried much farther in Germany than else where. But the outstanding feature of the submarine campaign was the thor oughness with which the two factors— the torpedo and submarine—had been adapted to each other. Both the British and the American navies took the lessons of the war to heart and both have now, a little late, carried both the torpedo and the submarine far beyond the point attained by the German navy at its best.
Figure 1 shows the principal features of the torpedo. At the forward end is the war-head, A, carrying the explosive charge, 600 pounds of gun-cotton or tri nitro-toluol. The fuse by which the charge is exploded on striking projects from the nose of the war-head but is rendered inactive until the torpedo is fired by a safety device which is re leased by pressure of the water. For purposes of drill the war-head is replaced by an exercise-head made of soft metal which collapses when it strikes a hard surface, thus indicating that the target, often the side of a friendly battleship, has been hit.
• Immediately abaft the head is the air flask, B, a large compartment charged with air under high pressure and fur nishing the motive power for the engine, D. In a pipe leading from the air-flask to the engine is the starting-valve, con nected with a small lever on the outside of the torpedo which is tripped auto matically when the torpedo is fired.
The engine in the latest American tor pedo is a turbine, but reciprocating en gines are still used abroad. The shaft runs through the after-body, E, to the propellers, of which there are two, RR, in tandem, one being keyed to the shaft and the other to a sleeve around the shaft and connected with it by a beveled gear. The propellers turn in opposite directions, one right, the other left, and must be balanced perfectly, as the slight est difference in their action would cause the torpedo to diverge from its initial course and might make it run in a circle and, in an extreme case, strike the ship from which it had been fired.
The rudder, R, abaft the propellers, is placed horizontally, not vertically, its pedo. The essential feature of this de vice is the utilization of the pressure of the water, which varies with every varia tion in the depth, to actuate the horizon tal rudder already described and so steer the torpedo up or down, as may be neces sary. The figure shows the immersion chamber (water-tight), and the engine compartment (open to the sea), sepa rated by a water-tight bulkhead. In the immersion-chamber is a sleeve carrying the hydrostatic-piston, which is held by a spring in contact with a flexible dia phragm forming a part of the water tight bulkhead. The tension of the spring can be varied to correspond with the pressure of the water for any desired depth. If we suppose the spring to be given a tension equal to that of the water at a depth of 15 feet, the piston will remain at rest when the torpedo is run ning at that depth. If the torpedo rises, the pressure of the water on the flexible diaphragm will be less than the tension of the spring and the piston will move to the right, carrying with it a rod which is attached to the rudder, and steering purpose being to steer the torpedo up and down, not to right and left. Very small vertical rudders are used in con nection with the Gyro gear, described later, but these are not shown in the drawing.