Diving Gear.— The diving °hydroplanes" (horizontal rudders) are operated similarly to the rudder. When the diving rudders are at bow and stern there are generally two hand wheels and the operators receive each instruc tion from the first officer. In sight of opera tors are depth gauges (the depth attained is read on a pressure diagram) and two indi cators display position of rudder and inclina tion of the vessel respectively. The submarine under ordinary conditions cannot remain be low water unless under way, at least slowly, but when it is necessary to stay in one spot for a period there is available the "statical div ing gear° which admits and ejects a small amount of water into or from the central bal last tank as the vessel shows inclination to rise or sink from her position.
Air System.— The need of air on board is for purposes besides breathing. Air is installed in seamless steel flasks compressed 2,500 pounds pressure per square inch and others at 1,000 pounds. After reduction of the pressure by valves the first kind is used for blowing out the water tanks, for charging the torpedoes' air chambers, for charging the flasks for firing the torpedoes, for refreshing the air breathed by the crew and for blowing the whistle; the latter pressure air is required for starting the Diesel engines.
Water Piping System.— Several pumps driven by electricity are generally installed to give a duplicate system of piping to each tank and they are so distributed as to preclude all pumps being thrown out of commission in an accident.
Refrigerating System.— This is installed for campaigns in tropical waters.
Heating System.— This is installed for campaigns in frigid waters as the North Sea, north Atlantic, etc.
Anchor Gear.—In great storms on certain occasions anchoring is an urgent need. In spite of the difficulties attending the invention of a practical device in recent years most large sub marines are equipped with two located on bow and capable of use while submerged, operated, of course, from the inside, but for fear of in ability to disengage the anchor when let down, a method had to be devised to cut the cable or slip it.
Navigating Appliances.— Under submerged conditions a gyroscopic compass set is, of recent years, considered among the necessities. It consists of the master compass in the central station and three repeating compasses magnet ically operated by the former and located at the steering stations. A device for depth sounding is also necessary as the submarine often runs in uncharted waters. The engine-room tele graph, speaking tubes, ship-lights, etc., are those
common to ordinary ships.
Air Regenerating System.—A few navies supply each submarine compartment with a ves sel containing a chemical to absorb carbon dioxide and several flasks of compressed oxy gen for emergencies when the vessel has to stay submerged over 24 hours and the air becomes vitiated.
External Fittings.—All submarines except the Laurenti type carry a walking platform con structed with light metal plates and which also answers as a smooth surfaced covering to the anchor gear, entrance and escape hatches, lift ing eyes, engine exhaust pipes and other pro jections that would afford resistance in navi gation. The conning tower, located midships, has been greatly increased in dimensions in re cent years to afford space for navigating the vessel on the surface when stormy weather forbids using the bridge. Some of the German conning towers reach nine feet above the upper deck. In the German boats one of the peri scopes enters the conning tower and navigation in such is carried on in the conning tower when slightly submerged and, therefore, has to be sufficiently roomy to hold two or three men. In the walls of the conning tower are eight or so sighting ports fitted with plate glass about an inch thick to resist the great pressure; bronze port covers are also provided to aid in withstanding the pressure when very deeply sub merged or when the glass gets broken. A port able railing is provided for use around the superstructure deck and is removed on sub merging. Exposed to view outside the hull are a towing hook for use when disabled and abaft the forward bow are the diving rudders, some of which fold up into a pocket leaving the space occupied flush and as they are only in use when submerged they are operated from inside the hull. On the deck is the bell for signaling under water. (See SUBMARINE SIG NALING). The perpendicular pipes that pro ject from the wave-breaker are ventilators com municating with the living quarters and engines. Large submarines lately carry a folding-boat that is stowed in the superstructure.
Living Arrangements.— On the larger or sea-going boats the average of three officers and 20 men have three separate cabins fitted up rather similarly to the quarters on a steam ship, with plenty of locker accommodation and steam-heated in cold weather. Steel work is encased in compressed cork to absorb moisture. The cook's galley is equipped with electric range, oven and hot-water reservoir. Coffee and soup are kept heated electrically in urns.