A Submarine Entrapped by Nets.
"Open the diving-valves! Submerge!"
The valves were flung open and the compressed air escaped hissing from the tanks. At the same time a gigantic, intermittent snorting ensued, like the blowing and belching of some prehistoric monster. There was an uncomfortable pressure in our ears, then the noise became more regular, followed by a buzzing and a shrill hum. All the high notes of the engines in the central station intermingled and made a bewildering noise. It was like a mad diabolical singsong. And yet it was almost like silence after the dull, heavy pounding of the oil-motors—only more insistent and irritating. The penetrating hum in the various vents announced the fact that the diving mechanism was in operation. It moaned and sang lower and lower in the scale of tones. These slowly diminishing and steadily deepening tones give one the physical feeling of mighty volumes of water pouring in and flooding full.
You have the sensation of growing heavier and sinking as the boat grows heavier and sinks, even though you may not be able to see through the turret window, or the periscope, how the bows are gradually submerged and the water climbs higher and higher up the turret until all things without are wrapped in the eerie twilight of the depths.
The faithful lamps burned, however, and then a real silence suddenly ensued. There was no sound but the gentle trembling rhythm of the electric engines.
I then gave the order:
"Submerge to twenty meters!"
"Both engines half steam ahead!"
I was able to follow our submersion by means of the manometer. Through flooding the tanks, the boat is given several tons over-weight and the enclosed ship's space is made heavier than the displaced quantity of water. The titanic fish, therefore, began to sink downward in its element, that is to say, it began, in a certain sense, to fall. At the same time the electric engines are put into motion and the propulsive force of the propellers acts upon the diving rudders and causes the sinking to become a gliding. After the required depth has been reached—something which may easily be read from the manometer that records the depth—all further sinking may be stopped by simply lightening the hull, which is done by forcing out some of the water in the submarine's tanks. The furious growling of the pump is always a sure sign that the required depth is being approached. The noise ceased, only the electric motors continued to purr, and the word came from the central station:
"Twenty meters—even keel!"