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 teries, steam motors, oil motors, and oil give off gases which are not only annoying and injurious. but may prove dangerous. It may be possible to reduce troubles of this sort to satisfactory limits by inclosing the machinery in air-tight casings, but in the handling and inspection some gas is sure to escape. There can be no cooking, no proper sleeping aeeommodations, no proper water closets, and the natural light is feeble. The mo tion is as trying as it is on a surface boat. A short consideration of these things is sufficient to show that the ease of securing fair habitability increases with the size of the boat, to which of course there is a limit.
The conditions affecting the stability of an en tirely submerged vessel differ considerably from those affecting the stability of one floating on the surface. (See SHIPBUILDING.) Since the sectional area of the immersed body remains un changed at all angles of heel, the position of the centre of buoyancy is constant; the righting mo ment therefore grows more slowly as the boat heels. By suitable ballasting or arrangement of weights adequate transverse stability is not very difficult to attain. But longitudinal stability is quite another matter. Any possible assistance from ballasting or the arrangement of permanent weights is insignificant, and the change of trim due to the using of fuel and shifting of weights (torpedoes, men, liquid in partly filled tanks, etc.) is a very serious matter. It is counteracted by the use of horizontal rudders, or shape of the hull, or quickly shifting water-ballast. if the boat has a slight surplus buoyancy the tendency to rise to the surface can be counteracted by vanes or the shape of the head which tends to make the boat descend so long as it is moving. But as the effect of hull shape or permanent vanes changes with the speed, while the buoyancy effort is constant, horizontal rudders are a neces sity. From these facts it follows that short, deep, and broad boats are most stable, but such a shape is incompatible with speed.
The difficulties experienced in dis charging torpedoes are closely connected with the question of stability. In ad dition to confined space in which tor pedoes are operated, and the difficulty of giving them the correct direction at the moment of firing, it is necessary that the boat should be nearly hori zontal when the torpedo is fired, else the latter will take too deep a dive or rise to the surface at the beginning of its run. The shock of firing and the sudden release of weight at the bow as the torpedo leaves it causes great longi tudinal disturbance in the boat, and may bring it to the surface, while the change in permanent trim adds to the difficulty of maintaining a constant depth.
The submarine torpedo boat as de veloped in 1903 was certainly far from a perfect weapon, being of little use except in smooth water, difficult to use at night, and having a very short radius of action. But. under favorable circumstances, it was thought that it might achieve a great sue eess, while the knowledge of the presence of submarines in a port cannot but have a powerful effect upon the nerves of the officers and crews of blockading vessels.
When or by whom was built the first sub marine boat will probably never be known. It is said that Alexander the Great was interested in submarine navigation, while subaqueous at tack of vessels was studied at least as early as the thirteenth or fourteenth century. 1\1. Del peueh states that some English ships were de stroyed in 1372 by fire carried under water. In the early part of the seventeenth century sub marine boats were numerous. and in 1624 Corne lius Drebbel exhibited to King James I. on the Thames a submarine boat of his own design. By 1727 no less than 14 types of submarines had been patented in England alone. In 1774 Day began experiments with a submarine boat at Plymouth, England, losing his life in the second submergence trial. In the following year David Bushnell built his first boat, with which Sergeant Lee attacked II. N. S. Eagle in New York Har bor. Lee actually got under the ship, and the attack failed only because the screw by which the torpedo was to be attached to the Eagle's bottom was not sharp enough. Robert Fulton's experiments in France and America (1795-3812) demonstrated that a vessel could be built which could descend to any given depth and reascend at will. Plunging mechanism was devised about the middle of the eighteenth cen tury, but Fulton developed the vertical and hori zontal rudders and provided for the artificial supply of air. A form of periscope existed in 1692 and an improved kind was patented in 1774; in 1854 Davy still further developed it. Phil lips's wooden boat on Lake Erie was crushed by the water pressure, and the same fate befell Bauer's iron boat Plongeur-ilarin (Fig. 1 on Plate) at Kiel in 1S50. In 1863 McClintock and Howgate built a semi-submarine hand-propelled boat for the attack on the Federal fleet. but it sank four times, each time drowning the entire crew of eight men. In the same year several larger boats propelled by engines were commenced. in Europe. and these at intervals were followed by others designed by Hovgaard, Coubet, ZtildC?, Nordenfeldt, Tuck, Holland, etc. The French Navy began experimenting with submarine boats about 1885. The Gyninote was built in 1888 and the Gustave zede in 1893. The Morse was com menced in 1894, but remained uncompleted until 1899, pending additional experiments with the Gymnote and the zede. In that year the eon struetion of submarines was actively commenced, 10 being launched in 1901. In 1886 Nordenfeldt built two large submarines for Turkey, but little was ever done with them after they passed into Turkish hands. In 1889 Spain built the Pcral, Portugal following with the Plongcur in 1892. Italy built the De/fino in 1895. The United States had the submarine boat under considera tion for several years. The first boat ordered (about 1895) was never completed, but seven of the Holland type were ordered in 1900 and one was purchased when nearly complete early in that year.
Consult: Sleeman, Torpedoes and Torpedo War fare (2d ed., Portsmouth, England, 1889) ; Del pencil, La norigation sous-marine travcrs les slides (Paris, 1902) ; Burgoyne, Submarine Navigation (London and New York, 1903) ; Bu chard, Torpillcs et tore illrurs ( Paris, 1889) ; Proceedings of the United States Naval Institute, particularly No. 100, December, 1901 (Annapolis, current).