deviation takes place, and completes the circuit through the corresponding electromagnet, which attracts the armature and causes the disk to move, so as to diminish the supply of water to one motor and increase it to the other, and so cause the torpedo to again assume the required direction.  Supposing the object which it is intended that the torpedo should strike be a large mass of iron, such as an ironclad, the needle will be attracted, and, making the corresponding contact, will cause the torpedo to be steered directly away from the object.  In order to prevent this, a second compass, Q, is mounted in the front of the torpedo, and when attracted by a mass of iron, it short-circuits the battery, D, and thus prevents the armature being attracted, and consequently the torpedo from deviating.  This needle is also capable of slight movement in a vertical plane, so that when passing over or under a mass of iron it is attracted downward or upward, and completes a circuit by means of the stops, which operate so as to explode the charge.  The charge can also be exploded in the ordinary manner, viz., by means of the firing pin, X, when the torpedo runs into any solid object.

The depth at which the torpedo travels below the surface of the water is regulated by means of a flexible diaphragm, M, secured in the outer casing and connected to a rod sliding freely in fixed bearings.  A spiral or other spring, O, is compressed between a color on the rod and an adjustable fixed nut, by which the tension of the spring is regulated so that the pressure of water on the diaphragm, A, when the torpedo is at the desired depth just counterbalances the pressure of the spring, the diaphragm being then flush with the outer casing.  The rod is connected by suitable levers to two horizontal fins, S, pivoted one on either side of the torpedo, so that they shall be in equilibrium.  Should the torpedo sink too deep or rise too high, the diaphragm will be depressed or extended, and will operate on the lines so as to cause the torpedo to ascend or descend as the case may be.

In order to avoid the risk of a spent torpedo destroying a friendly vessel, a valve is arranged in any suitable part of the outer casing, and is weighted or loaded with a spring in such a manner that when under way the pressure of the water keeps the valve closed, but when it stops the valve opens and admits water to sink the torpedo.

In our description we have only given the main features of the invention, the inventor having mentioned to us, in confidence, several improvements designed to perfect the details of his invention, among which we may mention the steering arrangement and arrangements for attacking a vessel provided with what our contemporary, Engineering, not inaptly terms a “crinoline,” i. e., a network for keeping off torpedoes.  The transverse dimensions of our engravings have been considerably augmented for the sake of clearness.—­Mech.  World.