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* TORPEDO BOAT. 358 TORPEDO BOAT. knots) specially designed torpedo boat was built by Thornyeroft of Chiswick, England, for the Norwegian Government and was fitted for using the Harvey towing torpedo, then in nuich favor. In the next year both Thornyeroft and Yarrow (of Poplar, near London) constructed boats for various foreign governments, and they built sev- eral in the ensuing year, but none for Great Britain, About the same time Herreshoff com- pleted a very fast boat for the United States Navy. In 1877 Herreshoff brought out the first boat fitted to use Whitehead torpedoes, and al- though many subsequent boats were designed to carry spar torpedoes, the Whitehead rapidly made its way, so that by 1880 it had practically dis- placed all rivals except the Howell and Schwartz- kopf, which were of somewhat similar type. The advent of the 'destroyer' class of boat was brought about by the realization of the inade- quacy of the existing means of defense against torpedo attack. The first boat was completed for the British Na^^ in 1893, Experience with these craft demonstrated their value both as scouts and picket boats against torpedo boat at- tack, and also showed that under many circum- stances they were available and desirable as tor- pedo boats. Bibliography. For further information, con- sult: Sleeman, Torpedoes and Torpedo Warfare (2d ed,, Portsmouth, England, 1889) ; Arm- strong, Torpedoes and Torpedo Vessels (2d ed., London, 1902) ; Johnson, Defense of Charleston Harbor (Charleston, 1890) ; Scharf, History of the Confederate Navy (New York, 1887); An- nual of the Office of Naval Intelligence (United States Navy Department, Washington, current) ; Brassey, Kaval Annual (Portsmouth, annual) ; Buchard, Torpilles et torpillenrs (Paris, 1889). See also articles on Torpedo; Torpedo Boat, SUBM.RIKE; and TORPEDO NET. TORPEDO BOAT, Scbmaeine. Modern sub- marine torpedo boats are of two kinds, the sub- merged and the suhnicrgible. The submerged, when in light cruising condition, moves with only a small percentage of the hull above water; the submergible cruises on the surface much like an ordinary torpedo boat, which it resembles exter- nally. The difference in principle between the two types is slight, but in construction details it is very marked. Submerged boats are usually nearly cylindrical with pointed ends, the general shape being much like that of a Whitehead tor- pedo. Submergence is effected by admitting water to the ballast tanks or by means of in- clined rudders or both. Submergible boats have two hulls, one inside the other. The outer hull resembles closely that of the ordinary torpedo boat, but has as few projections as possible rising from the general outline, in order to present a smooth surface when submerged. Inside this there is a second hull of nearly circular cross- section and as large as the shape of the outer boat permits. To effect submergence water is first admitted to the space between the hulls, and this brings the boat to the 'awash' condition. Further submergence is effected by permitting the ballast tanks to fill. The advantages of each type are apparent. The submerged boat is ready for nearly instant service, but cannot cruise with comfort to the crew. The submergible boat af- fords fair speed and comfort when cruising, but considerable time is required to effect its sub- mergence. The section (Fig, 4) of the Holland submarine boat shows the general features of a submerged boat; similar boats have also been built for the British Navy, France, which is building more submarines than any other nation, is the only one using the submergible boats, and they form but a small part of those she has completed or under construction. For the number of boats completed and under construc- tion in the various navies of the world in 1903, see N.wiES. The dilliculties in the way of submarine navi- gation are: (a) difficulty of securing safety; (b) of obtaining a fair speed; (c) of steering; (d) of securing habitabilit}-; (e) of insuring sta- bility; to which is to be added, for submarine torpedo boats, the difficulty of directing and discharging the torpedo. In the present state of develojnnent submarine boats can be made fairly safe. The problem of reaching a speed in excess of 10 knots when wholly submerged is a difficult one. Storage batteries are too heavy (at least all types now known) for the purpose of furnishing sufficient power ; steam is inadmissible for obvious reasons; and the only practicable m.a- chine seems to be an explosive motor developing a high pressure in the engine. So far no efficient means of keeping the exhaust gases from escap- ing into the boat has yet been devised ; and even if siich means were found it is possible that the escaping bubbles and the smell would enable the course of the boat to be ascertained and followed. As to steering and directing the course, there remain several imperfectly solved problems. It is impossible when under water to see more than a few feet ahead with the boat at rest, and the difficulty increases with the speed. Even when near the surface of the water the hull of a large ship is undiscernible beyond 100 feet, A sensi- tive compass with adequate directive force is possible only if the hull is made of copper, bronze, aluminum, or some other non-magnetizable metal. The most promising device is the periscope, which ( like a camera obscura ) consists of a tube with a prism or inclined mirror at the upper end with a reflecting table below. The upper part of the periscope is designed to project several feet above water when the boat is entirely sub- merged. The unsteadiness of the boat, bow-ever, interferes seriouslj- with the effectiveness of this instrument: moreover, the projecting tube may betray the boat's position. In place of a compass a g^'roscope has been experimented with, but the results were not satisfactory. All boats are fitted with small conning towers projecting a short distance above the hull and having glass covered peep holes of considerable size. This conning tower can be used when cruising at the surface and its top may be opened if the water is ver_y smooth. In most boats the opening in the top of the conning tower forms the principal way of ingi-ess and egress. To attain a reasonable habitability in a sub- marine boat is very difficult indeed. The boats are not easily susceptible of being warmed or cooled; in fact, few attempts have been made in either direction, so that in very warm water or in very cold it is possible to remain in the boats only a very short time without suffering from the unsuitableness of the temperature. So far as the vitiation of the air due to the breathing of the crew is concerned, the problem may be regarded as practically solved; but storage bat-