The great compartment amidships given over to machinery is a place to test the nerves. The aisle down the centre is scarcely two feet wide and on each side are whirling wheels, engines, and electric motors. Only the photographs can give a clear idea of the crowded appearance of this compartment. It contains steering wheels, the gyroscopic compass, huge valves, dials showing depth of submergence, Kingston levers, motor controllers, all polished and shining, each doing its work and each easily thrown out of gear by an ignorant touch.
The author once spending the night on a United States man-of-war was shown by the captain to his own cabin, that officer occupying the admiral's cabin for the time. At the head of the bunk were two small electric push buttons absolutely identical in appearance and about two inches apart. "Push this button," said the captain genially, "if you want the Jap boy to bring you shaving water or anything else. But be sure to push the right one. If you push the other you will call the entire crew to quarters at whatever hour of night the bell may ring."
The possibility of mistaking the button rested heavily on the writer's nerves all night. A somewhat similar feeling comes over one who walks the narrow path down the centre of the machinery compartment of a submarine. He seems hedged about by mysterious apparatus a touch of which, or even an accidental jostle may release powerful and even murderous forces.
While the submarine is under way, submerged, the operator at every piece of individual machinery stands at its side ready for action. Here are the gunner's mates at the diving rudder. They watch steadily a big gauge on which a needle which shows how deep the boat is sinking. When the required depth is reached swift turns of two big brass wheels set the horizontal rudders that check the descent and keep the boat on an even keel. Other men stand at the levers of the Kingston valves which, when open, flood the ballast tanks with water and secure the submergence of the boat. Most of the underwater boats to-day sink rapidly on an even keel. The old method of depressing the nose of the boat so as to make a literal dive has been abandoned, partly because of the inconvenience it caused to the men within who suddenly found the floor on which they were standing tilted at a sharp angle, and partly because the diving position proved to be a dangerous one for the boat.