Engineering Wonders of the World
Volume I

430 ENGINEERING WONDERS OF THE WORLD. provided along its lower edge to permit a ready entry of water when diving and an equally speedy emptying of the same at the surface. The conning tower, a circular steel tube of 4-inch thick armour, has at its top a clear opening 21 inches in diameter, closed by a hinged steel cover, and made water-tight against a rubber gasket by a toggle-locking device similar to that often employed for fastening French windows. In the wall of this tower are a number of ports or peep- holes permitting an all-round view. They are fitted with thick plate glass, and provided with steel sliding covers to seal them effectu- ally should the glass break under water. Small as the hull is, it has at the forward end two bulkheads which can be rendered entirely water-tight. These are a necessary provision against collision, and are amply strong enough to withstand any inflow of water. Besides the conning tower, which is too narrow to allow a stout man to enter the boat, there are two additional hatches suffi- ciently large to admit machinery parts and torpedoes into the hull. Finally, the exterior presents no projecting parts which might be entangled with ropes, nets, or cables, etc.— a most valuable feature. Turning to the means of propulsion, we find that the engine is of the internal-combustion type, and is driven by gasolene, of which 6,850 gallons are carried. The Means of indicated horse-power, with the engines making 340 revolu- tions to the minute, is 160, and the consump- tion at this rate is one pint of gasolene per horse-power per hour. The four-cylinder en- gine drives a steel propeller shaft 4 inches in diameter through clutch gearing such as is found in a motor car. All the bearings are lubricated automatically. On the surface the speed of this boat is 9 knots an hour. For running submerged, an electric motor, of the so-called “waterproof” type, develop- ing 70 horse-power at a speed of 800 revo- lutions, is fitted. Whether submerged or awash, the vessel’s speed is 7 knots. These two motors have each a double function. The gasolene motor is used (1) for driving the ship on the surface ; (2) for recharging the “ storage battery ”—when this is being done the engine is declutched from the propeller shaft. The electric motor (1) drives the ship either awash or submerged ; (2) starts the gasolene motor. The storage battery consists of sixty cells, and has a capacity of 75 horse-power for three hours. It need hardly be said that the battery and everything electrical within the submarine is carefully insulated from the hull. In addi- tion to these motors there is an auxiliary elec- tric plant of 10 horse-power for operating the bilge and tank pumps. The air supply for various purposes is ob- tained from an air-compressor driven through gearing by the main electric motor or gasolene engine, as the case may be. Air reservoirs of 69 cubic feet capacity, and able to stand a pressure of 2,000 lbs. to the square inch, are provided. The air stored therein is used, amongst other things, for expelling tor- pedoes from the single tube forward, and emptying the ballast and trimming tanks. An important feature in a submarine is the ventilation. This is provided mighly in several ways. All machinery exhausts into the interior of the ship. Exces- for most thor- the air-driven Ventilation. sive air pressure within the vessel is relieved by special safety-valves. Ventilators, with electrically-driven fans, are installed over the engine and at other suitable points to allow of complete ventilation when the boat is on the surface. The exhaust gases from the gasolene engine are led outside the boat through water- jacketed piping, carried aft along the hull, and set free under the superstructure at the stern. A submarine must be provided with many gauges, and with instruments to record accur-