By this I do not want you to take it that submarines are not provided with rapid-fire and quick-action disappearing guns at the present time; and should you or I take a look at them we would say that they are 99 per cent. perfect and that there is no need for further improvement. But that is because we are neither designers, nor builders, nor officers of undersea craft; and do not forget, either, that better things are always in order.
Courtesy of Scientific American
A 3½ INCH SUBMARINE GUN IN ACTION SHOWING THE DECK WELL AND MANNER OF OPERATION
Now, there are two kinds of rapid-fire, quick-action guns used for submarine armament and these can be told from each other by the way they are brought into action. They are (1) the spring action gun, and (2) the compressed-air action gun.
The Spring Action Gun.—This type of submarine gun is made by the Krupps of Essen, Germany, who now are building the U-boats for the Central Powers.
This gun is mounted on the deck, over an opening in it called a deck-well, and this arrangement allows the gun to be stowed away in it. This is done to get rid of the resistance the water would have on the gun if it remained fixed on deck when the boat is running submerged.
Although the deck-well is closed with hatches it is not watertight, and the fittings, such as the sights and range finders, are taken off to keep them from rusting when the gun is in the well.
A diagrammatic sketch of the gun and its housing is shown in [Fig. 46]; the gun is mounted on a swinging frame by trunnions, and the frame is fixed to a pedestal. A strong spring in the bottom of the well supplies the power needed to throw the gun up and bring it into position.
When housed in the well the gun lays on its back, as shown by the dotted lines, and this presses down on the spring. The tension of the spring is enough to force the gun up and into place the instant the catch which holds it is released.