Page:The American Cyclopædia (1879) Volume IX.djvu/396

 3S3 IRON-CLAD SHIPS the earlier English ironclads were constructed with deep frames running in a longitudinal di- rection through the greater part of the ship's hull, combined with numerous strong trans- verse frames, formed of plates and angle irons. In fact, up to the height of the armor, the lon- gitudinal framing of the older ironclads closely resembles that of the roadway of a common English girder bridge of iron, in which the principal or longitudinal strength is contribu- ted by the continuous girders that stretch from pier to pier, and the transverse framing con- sists of short girders fitted between and fas- tened to the continuous girders. If such a structure be conceived to be curved trans- versely to a ship's shape, and the under side to be covered with iron plating, a fair idea will be had of the construction of the hull of the "Warrior. If instead of this arrangement the continuous longitudinal girders be con- siderably deepened and the transverse girders be replaced by "bracket frames," and, after curving these to the ship's form, both the upper and lower side thereof be iron-plated, a cor- respondingly good idea will be had of the con- struction of the hull of the Bellerophon. In other words, the construction of the latter is identical with the cellular system of the Menai and other tubular bridges, which best combines lightness and strength in wrought-iron struc- tures of tubular cross section. This double- skinned or tubular system, in addition to giv- ing greater strength and safety than the single- skinned system, is also better adapted to resist the explosive effect of torpedoes, which are fast becoming one of the most important ad- juncts to naval warfare. No ship's bottom can be made strong enough to resist the shock of a torpedo's explosion, and consequently Mr. Reed provided as far as possible against the danger of sinking by dividing his ships into water-tight compartments. Notwithstanding the superior strength and safety thus given to the Bellerophon, the weight of her hull was considerably less than it would have been if built of wood, and was very much less than the total weight of armor, armament, and equipment. In the wood-built ironclads the weight of hull was generally about equal to that of the total weight carried, and in the earlier built ironclads the hull was heavier than the cargo. In the Black Prince the weight of hull was 4,969 tons, and the total weight car- ried 4,281 tons. In the Bellerophon the hull, with thick skin plating and extra girders, was 3,652 tons, while the total weight carried was 3,798 tons. In the case of the Monarch, a turret ship built after this system, the weight of the hull is 3,674 tons, while the weight car- ried is 4,632 tons. In all the later ships con- structed by Mr. Reed the carrying power is much greater than the weight of the hull, and is due mainly to the improved structural ar- rangements introduced by him. This system is known among naval constructors as the " bracket-plate system," and is now generally employed even by the private ship builders of England who build ships of war. Iron-clad ships are substantially of two forms or types : those in which the batteries are protected by armor laid upon the walls of the ships, such as the New Ironsides. "Warrior, Hercules, and Bellerophon, and those carrying their batteries in turrets, such as the Miantonomoh, Monitor, Glatton, Thunderer, and Devastation; and they are divided into classes according to their uses for cruising, defending harbors, guarding coasts, or operating upon rivers and lakes. While there is a certain similarity in all the vessels of each class, there are also many dif- ferences in details, according to the intended use. The Warrior is armed only at the middle, with 4-J-inch plates, while both bow and stern, including the steering gear, are exposed to shot and shell. In all the more recent English ships this central battery or " box " has been enlarged by a continuous belt of armor extend- ing from stem to stern, and protecting the region of the water line and steering gear. The Warrior's armor is of uniform thickness ; but in recent ships the most vital parts, such as the region of the water line and over the machinery, have been further protected by thick armor, additional backing, and iron bulk- heads fitted inside. The Warrior possesses only broadside fire ; all the later vessels have their fighting capacity increased by bow and stern fire of greater or less extent. The War- rior has only her main-deck battery armor- plated; recent ships have a protected upper- deck battery. The Warrior has her guns well spread out ; later ships carry their battery con- centrated, and composed of much heavier guns. The Warrior was made extremely long with a view to speed ; recent ships are much shorter in proportion, and are handled more easily. The Warrior has a single-skinned hull and com- paratively light and weak framing ; later ships are double-skinned, with deep, strong framing and water-tight compartments. The armor of the Warrior, as before stated, is only 4| in. thick ; that of the Bellerophon is 6 in., of the Hercules 9 in., of the Hotspur 1 1 in., and that on the sides of the monitors Glatton, Thunderer, and Devastation is 12 in., while their turrets are 14 in. Presuming that the resistance offered by armor plates to penetration varies as the square of the thickness, which is approximate- ly correct, the armor of the Bellerophon is nearly twice as strong as that of the Warrior, of the Hercules about seven times, of the Hot- spur six times, of the Glatton seven times, and of the turrets of the latter nearly ten times. The guns (rifled) used by the Warrior weigh 4| tons, those of the Bellorophon 12 tons, of the Hercules 18 tons, of the Glatton 25 tons; while those of the Thunderer and Devastation weigh 30 tons. The necessity of carrying such armor and guns, and of firing ahead and astern, as well as from the broadside, has rendered es- sential many changes in the sizes, forms, and arrangements of the sides, decks, sind batteries