Krupp Gun. The metal used in these celebrated guns is cast steel, a composition of puddled steel and wrought iron. The wrought iron is obtained from the best hematite ores of Europe, the puddled steel from the spathic ore of Siegen, in the immediate vicinity of the works. The proportions of each metal, the details of their preparation, as well as certain ingredients guessed at but not known, remain a secret with the manufacturers. Manganese in small quantity is supposed to be present and to exercise an important influence. The result is a metal equal in elasticity and tensile strength to the best English steel, the excellent quality of which is largely due to “oil tempering,” a process entirely omitted in the Krupp gun. The ingots forming the different parts of the gun are cast in cylindrical iron molds, an operation requiring the greatest care to prevent the imprisonment of air or other gases in the casting,—a defect which the tenacious character of the metal renders fatal. Subsequent hammering only increases the trouble by involving a larger area. As soon as the ingot is hard enough to permit handling it is removed from the mold and cooled slowly in ashes. It is next brought to a working heat in a furnace, placed under a steam-hammer weighing from 1 to 50 tons, according to the size of the ingot, and drawn out to the required length and thickness, when it is again buried in ashes and gradually annealed to remove the tensions induced by hammering. From the rough ingot thus prepared the tube forming the barrel is made directly by boring, turning, and rifling. The ingots intended for hoops, trunnion bands, etc., are cut up into short lengths, which are formed into rings without weld by being split through the centre within a certain distance of the ends, after which the slit is gradually widened to a circle by swaging. The parts when finished are carefully annealed.
The Krupp gun consists of a central tube or barrel, comprising the greater mass of the gun, and a series of encircling hoops. The tube has a thickness of about eight-tenths of the caliber from a point over the front of the charge to the termination of the rings or hoops, whence it is conical, tapering to a thickness of about half the caliber at the muzzle. From the seat of the charge breech-wards the tube thickens rapidly by a series of steps to a cylinder about 11⁄5 calibers thick. The hoops overlie the tube from the cylinder in rear to the base of the cone in front, covering about half the total length of the tube. The hoops are put on in layers, the number of layers being determined by the size of the gun. The 6-inch gun has one, the 8- and 9-inch two, and the higher calibers have three layers of hoops. The hoops are shrunk on at black heat, the different layers being held in place by small key-rings.
The rifling for Krupp guns is polygrooved, the twist uniform, the grooves being gradually narrowed towards the muzzle for the suppression of windage. The chamber in which the shot and charge rest is a little larger than the bore, though they coincide at the bottom. This makes the passage of the projectile into the bore direct and prevents the abrasion which would occur if tilted upwards in leaving its seat. Moreover, the shot is “centred”—that is, has its axis in the axis of the bore—from its entry into the gun.
The breech-mechanism is essentially that of Broadwell. The breech is closed on the “sliding block” principle. Through the cylindrical part of the [barrel] in rear of the rings, from one side to the other, a slot is cut in which the breech-block slides horizontally, alternately exposing and closing the rear of the chamber. The block is run in and out by an attached screw, which works partly in the upper wall of the slot. The motion of the block is governed by guides in the upper and lower walls of the slot slightly inclined from the perpendicular to the axis of the piece. The rear of the slot is so cut that the block is wedged firmly against it when it is home. The block is locked in this position by a large screw, which catches in certain threads cut on the rear wall of the slot. The block is furnished with an “indurator plate,” a disk of hardened steel, which is set in its face to receive the direct action of the powder gases. The vent is in the axis of the gun through the block. The gas-check used is the [Broadwell ring] (which see). The powder for all the large guns is the prismatic. (See [Gunpowder].) Both steel and cast-iron projectiles are used. The steel projectiles for armor piercing have their points water-tempered. Rotation being communicated by compression, the projectiles belong to the soft-jacketed class. The projectile is turned smooth in a lathe, pickled in dilute acid, and then put in sal-ammoniac to remove oil. It is next galvanized by immersion in molten zinc, then immersed in lead, and afterwards a heavy lead jacket is cast on it, which is turned down, leaving several prominent rings to facilitate compression into the grooves. In late years Herr Krupp has adopted for his large guns the American system of projectiles, having soft metal expanding sabots attached to the base, with a centring ring in front.
Krupp guns range in size from small field-pieces to a gun weighing 72 tons. The field pieces manufactured number several thousand. They form the official equipment of the German army, and contributed much to German success in the Franco-Prussian war. The large guns, comprising 6-, 7-, 8-, 9-, 10-, 11-, and 12-inch guns, have been made in large numbers, and have found a ready sale in Germany, Russia, and Turkey.
The largest guns are a 14-inch gun weighing 56 tons, and a 153⁄4-inch weighing 72 tons. (See [Cannon].) Herr Krupp is also a large manufacturer of gun-carriages of all kinds. His partiality for steel has led him to use it almost exclusively in his constructions. He has inherited likewise the aversion of the great Borsig for welding; and a noticeable feature of his guns is an absence of any weld. The “coil” principle, so well adapted to develop tangential strength, is also omitted, the character of the metal being relied upon to resist strains “across the grain.”
Perhaps the most novel piece of ordnance of modern times is Krupp’s non-recoiling shield gun. This gun is made with an enlargement around the muzzle in the shape of a large ball, which is held in a socket formed in a heavy armored shield protecting the gun in front, the arrangement giving a veritable ball-and-socket joint, about which the gun is elevated and traversed. On shipboard or in a fortification the shield would form a part of the armor or scarp wall. A narrow slit above the ball is used in pointing by the gunner, who for this purpose sits astride of the gun. The problem solved by this unique arrangement is the entire suppression of recoil, the strain being absorbed by the massive shield. In the late experiments at Mappen, 1879, the triumphs of Krupp guns culminated in the performances of this novel piece of ordnance. Its action was satisfactory in every respect, and so slight was the shock communicated to the gun that the gunner did not deem it necessary to dismount, but kept his seat astride of it during the firing.
Krupp’s Steel Works. On account of the wide-spread reputation which the steel produced in the great works of Krupp at Essen, in Rhenish Prussia, has obtained, it is necessary that these works should receive a brief notice. They were founded by Friedrich Krupp in 1810, and were continued by his sons after his death in 1826. For the last fifty years they have been increasing annually from one-sixth to one-third in size, until now they cover about 500 acres, and give employment to about 20,000 persons, including those engaged in building, and in the mines and smelting-houses. For large metallurgical works Essen is favorably situated, being in the centre of a coal-bearing area, where coal of the best quality can be procured cheaply, and near mines of manganiferous iron ore, which has been found excellently adapted for the manufacture of steel; but it is believed that the admirable organization of every part of his manufactory has conduced as much as anything to the great success of Krupp. The articles manufactured consist principally of rails, tires, crank-axles, shafts, mining pump-rods, gun-carriages and guns, the proportion of ordnance being about two-fifths of the whole. Guns have been made at Essen for the Prussians, Austrians, Belgians, Dutch, Italians, Turks, Japanese, and also for the English, although not directly ordered by the government. Since 1872 a field-gun invented by Krupp has been adopted by the Prussian government, and supplied to the whole army. The establishment possesses 286 steam-engines from 2 to 1000 horse-power, 1100 furnaces of various kinds, 71 steam-hammers, 264 smith’s forges, 275 coke-ovens, and 1056 planing, cutting, and boring machines. It burns over 1000 tons of coal daily, and has over 11,000 gas-burners, consuming in twenty-four hours 400,000 cubic feet of gas. It has, besides, a complete telegraph system, 800 cars, 15 locomotives, 33 miles of railway, over 3000 dwelling-houses, hospitals, chemical laboratory, a photographic and lithographic establishment, over 400 mines, 11 blast-furnaces and several smelting-houses which produce annually about 20,000 tons of pig-iron. These works have already produced over 18,000 heavy guns.
Kshatriya. The second or military caste in the social system of the Brahmanical Hindus.
Ku-Klux-Klan. A secret organization of ex-Confederate soldiers, who, for several years after the close of the civil war, by their murders and other crimes disturbed the tranquillity of the Southern States. Their victims were chiefly freedmen, and persons suspected of favoring the policy of the government. Stringent measures were taken against them by Congress in 1871, and they soon after ceased their disturbances.