Admiralty to get to work and produce a 'mine' that
would act in the way that Admiral Madden had suggested.
It proved to be very simple to construct an ordinary
steel cylinder filled with TNT; this was fitted with a
simple firing appliance which was set off by the pressure
of the water, and could be so adjusted that it would
explode the charge at any depth desired. This apparatus
was so simple and so necessary that we at once began to
manufacture it."
The depth charge looked like the innocent domestic ash can, and that was the name by which it soon came to be popularly known. Each destroyer eventually carried twenty or thirty of these destructive weapons at the stern; a mere pull on a lever would make one drop into the water. Many destroyers also carried strange-looking howitzers, which were made in the shape of a Y, and from which one ash can could be hurled fifty yards or more from each side of the vessel. The explosion, when it took place within the one hundred feet which I have mentioned as usually fatal to the submarine, would drive the plates inward and sometimes make a leak so large that the vessel would sink almost instantaneously. At a somewhat greater distance it frequently produced a leak of such serious proportions that the submarine would be forced to blow her ballast tanks, come to the surface, and surrender. Even when the depth charge exploded considerably more than a hundred feet away, the result might be equally disastrous, for the concussion might distort the hull and damage the horizontal rudders, making it impossible to steer, or it might so injure the essential machinery that the submarine would be rendered helpless. Sometimes the lights went out, leaving the crew groping in blackness ; necessary parts were shaken from their fastenings ; and in such a case the commander had his choice of two alternatives, one to be crushed by the pressure of the water, and the other to come up and be captured or sunk by his surface foe. It is no reflection upon the courage of the submarine commanders to say that in this embarrassing situation they usually preferred to throw themselves upon the mercy of the enemy rather than to be smashed or to die a lingering and agonizing death under the water. Even when the explosion took place at a distance so great that the submarine was not
