The sights and other attachments are fixed on the gun after it is brought into position and the whole operation of raising the gun from its well and putting on the fixtures takes just 20 seconds.
FIG. 46. HOW THE KRUPP OR GERMAN SUBMARINE GUN IS MOUNTED.
These guns have a bore of 75 millimeters[24]—equal to 3 inches—and 88 millimeters—equal to 3½ inches—respectively, and the shells they use weigh in the neighborhood of 25 pounds.
The Compressed Air Action Gun.—This kind of submarine gun is used on British undersea boats. It is mounted over a deck-well but inasmuch as the gun is lowered into the well with all the fittings on it the well has to be made watertight.
If you will look at [Fig. 47], you will see how the gun is brought into action. When compressed air is turned on in the cylinder, it forces the plunger on which the gun is mounted up above the level of the deck. The gun is fitted with fixed sights and a range finder, and is ready for use the moment it has been brought into place above the deck, the whole operation taking only 5 seconds.
FIG. 47. BRITISH AND AMERICAN-STYLE DECK GUN.
The guns of the Allies’ submarines have bores of 3 and 4 inches, and each one weighs nearly a ton. As a protection from enemy aircraft they have a wide range and can, if needs be, fire a shot at 90 degrees, that is, straight overhead.
How a Submarine Lays Mines.—The dangerous work of laying mines in an enemy harbor by a submarine is not as spectacular as torpedoing ships but it is an important part of the business of undersea craft.