The automatic apparatus by which the torpedo’s course is regulated is a very remarkable part of the invention, and it admits of the nicest adjustments. This was the crown of Mr. Whitehead’s ingenuity, but the details were, by an arrangement between the government and the inventor, not to be made public, though necessarily communicated to certain officers in the service, and known to the chief artisans employed in their fabrication. These persons are all, we believe, required to give pledges not to divulge the arrangement of particular parts. But such details could scarcely be made intelligible, even should they be interesting, to the general reader. The principles upon which the controlling apparatus are arranged may, however, be comprehended without difficulty. The tail of the torpedo is provided with two rudders, one in its central vertical plane, and the other in its central horizontal plane. Their action in directing the torpedo’s course is exactly that which the tail supplies to a fish, or the rudder to a boat. Suppose that while the torpedo is passing through the water the vertical rudder is by any means turned towards one side, the course of the metallic fish will be diverted towards that side; or again, a turning upwards of the horizontal rudder would have the effect of directing the nose towards the surface, and would make the torpedo rise, and so on. Now the positions of the horizontal rudder are regulated from the “steering chamber,” in which a heavy weight is suspended like a pendulum, so as to be capable of swinging fore and aft. This pendulous weight actuates the horizontal rudder through a system of rods and levers, so that when it hangs vertically the horizontal rudder is level, but if from any cause the nose of the torpedo were directed downwards, the pendulous weight would come to a more forward position in the steering chamber, and would raise the rudder, and thus turn the nose towards the surface until the original horizontal position were regained. In the contrary case, of course, the reverse action would take place. But the torpedo, while preserving a horizontal position, might tend to sink to too great a depth, or rise too near the surface, and this is prevented by another adjustment, namely, a piston receiving the pressure of the water, which, on the other side, is opposed by a spring. If the torpedo sinks a little the pressure increases, the piston, which moves with perfect freedom without allowing water to pass in, is forced inwards, and its movement is communicated to the same levers that connect the pendulous weight with the horizontal rudder, the latter is raised, and then the nose of the torpedo is directed upwards, and it consequently approaches the surface again. In the contrary case the spring, relieved from some of the external pressure, operates the levers in the other direction.