Another submersible of somewhat different design is the production of the Swedish inventor, Mr. Nordenfelt. This boat is 9-1/2 metres in length, and has a displacement of sixty tons. Like the Goubet it sinks only in a horizontal position, while the Holland plunges downward at a slight angle. On the surface a steam-engine of 100 horse-power propels it, and when the funnel is closed down and the vessel submerges itself, the screws are still driven by superheated steam from the large reservoir of water boiling at high pressure which maintains a constant supply, three circulation pumps keeping this in touch with the boiler. The plunge is accomplished by means of two protected screws, and when they cease to move the reserve buoyancy of the boat brings it back to the surface. It is steered by a rudder which a pendulum regulates. The most modern of these boats is of English manufacture, built at Barrow, and tried in Southampton Water.
The vessels hitherto described should be termed submersible rather than submarine, as they are designed to usually proceed on the surface, and submerge themselves only for action when in sight of the enemy.
American ingenuity has produced an absolutely unique craft to which the name submarine may with real appropriateness be applied, for, sinking in water 100 feet deep, it can remain below and run upon three wheels along the bottom of the sea. This is the Argonaut, invented by Mr. Simon Lake of Baltimore, and its main portion consists of a steel framework of cylindrical form which is surmounted by a flat, hollow steel deck. During submersion the deck is filled with water and thus saved from being crushed by outside pressure as well as helping to sink the craft.
When moving on the surface it has the appearance of an ordinary ship, with its two light masts, a small conning-tower on which is the steering-wheel, bowsprit, ventilators, a derrick, suction-pump, and two anchors. A gasolene engine of special design is used for both surface and submerged cruising under ordinary circumstances, but in time of war storage batteries are available. An electric dynamo supplies light to the whole interior, including a 4000 candle-power searchlight in the extreme bow which illuminates the pathway while under water.
On the boat being stopped and the order given to submerge, the crew first throw out sounding lines to make sure of the depth. They then close down external openings, and retreat into the boat through the conning-tower, within which the helmsman takes his stand, continuing to steer as easily as when outside. The valves which fill the deck and submersion tanks are opened, and the Argonaut drops gently to the floor of the ocean. The two apparent masts are in reality 3-inch iron pipes which rise thirty feet or more above the deck, and so long as no greater depth is attained, they supply the occupants with fresh air and let exhausted gases escape, but close automatically when the water reaches their top.
Once upon the bottom of the sea this versatile submarine begins its journey as a tricycle. It is furnished with a driving-wheel on either side, each of which is 6-1/2 feet in diameter and weighs 5000 lbs.; and is guided by a third wheel weighing 2000 lbs. journalled in the rudder. On a hard bottom or against a strong tide the wheels are most effective owing to their weight, but in passing through soft sand or mud the screw propeller pushes the boat along, the driving-wheels running “loose.” In this way she can travel through even waist-deep mud, the screw working more strongly than on the surface, because it has such a weight of water to help it, and she moves more easily uphill.
In construction the Argonaut is shaped something like a huge cigar, her strong steel frames, spaced twenty inches apart, being clad with steel plates 3/8-inch thick double riveted over them. Great strength is necessary to resist the pressure of superincumbent water, which at a depth of 100 feet amounts to 44 lbs. per square inch.
Originally she was built 36 feet long, but was subsequently lengthened by some 20 odd feet, and has 9 feet beam. She weighs fifty-seven tons when submerged. A false section of keel, 4000 lbs. in weight, can on emergency be instantly released from inside; and two downhaul weights, each of 1000 lbs., are used as an extra precaution for safety when sinking in deep water.
The interior is divided into various compartments, the living quarters consisting of the cabin, galley, operating chamber and engine-room. There are also a division containing stores and telephone, the intermediate, and the divers’ room. The “operating” room contains the levers, handwheels, and other mechanism by which the boat’s movements are governed. A water gauge shows her exact depth below the surface; a dial on either side indicates any inclination from the horizontal. Certain levers open the valves which admit water to the ballast-tanks in the hold; another releases the false keel; there is a cyclometer to register the wheel travelling, and other gauges mark the pressure of steam, speed of engines, &c.