Vertical and horizontal steel fins are fitted for the purpose of maintaining the torpedo in an upright position whilst passing through the discharge tube, or frame; the former fins run nearly the whole length of the weapon, while the latter are considerably shorter. The motive power of the torpedo is compressed air, forced by means of a powerful steam air compressing pump into a portion of the steel chamber (3) at a tension of upwards of 1000 pounds to the square inch, which is equivalent to about sixty atmospheres, and which by means of a set of small three cylinder Brotherhood engines, contained in the steel chamber (3), drives two screw propellers. These engines are capable of exerting a force of forty indicated horses, and yet only weigh about thirty-five pounds, from which it will be understood that to attain these results the workmanship and materials employed in their manufacture are of the very highest order and fineness. The torpedo is made of various sizes, ranging from 14' long and 14" maximum diameter to 19' long and 16" maximum diameter. _Capabilities of the Fish Torpedo._--The capabilities of the fish torpedo are as follows:-- 1.--If adjusted for a certain depth, from 5 to 15 feet, and projected from above water, or if started from the surface, or if discharged from a submerged tube, it will rapidly attain that depth, and maintain it during the run. 2.--If fired in still water, it will make a straight run in the line of projection, provided that an allowance has been made for the deflection due to transverse currents. 3.--It can be adjusted to stop after having run any distance up to its extreme range, and after stopping to sink, float, or explode. 4.--Its range and speed vary considerably, according to the pattern of the torpedo.