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GUNBOAT

815

GUNPOWDER

has been adopted in the U. S. navy. Other machine-guns in use are the Gardner and the Colt gun, the Hotchkiss two and 12-pounder mountain-guns. The modern improvements in guns are largely in what are known as quiekfiring or machine-guns. The guns used in Europe are made chiefly at the Krupp works or by Sir William Armstrong in Newcastle, England, whose guns are equally famous. See CANNON, RIFLE-, REVOLVER and ARTILLERY. See The Gun and Its Development by Greener; Modern Shotguns by the same; and American Inventions and Improvements in Small Arms, Machine-Guns etc. by General Norton.

Gun' boat, a small vessel armed with large guns and principally used for service on the coast and in rivers In their more modern form they have one large gun in the bow, pointed by a helm or by screws, these being only a floating gun-carriage. In 1907 the United States navy had 37 gunboats and in the same year Great Britain had 36.

Gun'cot/ton is an explosive substance made from cotton-wool. The first experiments were made by Schonbein, a German chemist, in 1845, wno found that cottonwool, dipped in a solution of nitric and sulphuric acids, could easily be set on fire, and while burning would explode. He called the new compound guncotton and proposed its use in place of gunpowder. Many experiments followed the discovery, and several attempts were made to introduce it into use. Its principal advantages over gunpowder are that it is not injured by water, and so it can be carried in a damp state, which makes it perfectly safe, and that it is smokeless. It is used in war largely for torpedoes and in mines. It is now used, after many unsuccessful attempts, as a constituent of certain smokeless powders. In the pure condition its explosion is too violent for use in guns, but by proper additions of other substances its speed of burning may be retarded. See Handbook to Modern Explosives by Eissler.

Gun'nery is the system of laws which regulates the making and using of all kinds of firearms, though the term " musketry" is sometimes given to the scientific use of small arms. The first book on the subject was written by an Italian mathematician, Tartoglia, who published his New Science in 1537. He also invented the gunner's quadrant. Galileo followed with his Dialogues on Motion in 1638. The real founder of the science was Benjamin Robbins, whose New Principles of Gunnery, published in 1742, treated of the force of gunpowder, the resistance of the atmosphere, etc. His invention for measuring the velocity of a cannon ball was used until superseded in 1862. In the use of firearms many problems have to be solved, and it has become one of the exact sciences. By means of mathe-

matical tables and other instruments the proper length, thickness and size of a gun, the charge, form of the ball, the time of flight, distance to which it will reach and elevation required for any range are all calculated, and every gun has its range -table, as it is called, set forth with all these items for the gunner's use. See CANNON, RIFLE and GUN. See Textbook of Gunnery by Mackinlay.

Gun'powder, an explosive mixture of saltpeter, charcoal and sulphur, well-known all over the world. The proportions of these materials used vary in different kinds of powder, as also in various countries. Its origin and early history are obscure. Fireworks were known in China at a very early period, but whether the Chinese or any other Asiatic people invented modern gunpowder is doubtful. It was, in any case, left for more western nations to develop the discovery of the Chinese; we find it first used by the Byzantine emperors, under the name of Greek fire, in the defense of Constantinople against the Saracens in the 7th century. Its first use in Europe in its present form was in Spain, both by Christians and Moors, in the i2th century, who had some rude sort of artillery. Roger Bacon first introduced it into England, This was early in the i3th century, but its preparation was so imperfect that it was of no use, until a German monk, Berthold Schwarz, about 1320 introduced a new method of manufacture. From that time the use of gunpowder became general throughout Europe, the Russians, who in i88p celebrated the sooth anniversary of its introduction into Russia, being the last to adopt it. In Queen Elizabeth's reign its manufacture was commenced in England, the great bulk used there having been obtained from abroad. At Waltham Abbey, a market town in Essex on the Lea River, 12 miles north of London, are the English government's gun-factory, gunpowder mills and large corditeworks. The English royal laboratory and ordnance-factories are at Woolwich, The materials used in making gunpowder — saltpeter, charcoal and sulphur — are first ground very fine, then mixed by hand in the proportion of 75 per cent, of saltpeter, 15 of charcoal and 10 of sulphur. When mixed they are wet, and worked in a powder-mill into a cake called a mill-cake, which is crushed into meal. This meal is again pressed into cakes, and the cakes broken into pieces and passed through a machine, which forms the powder into grains. It is then sifted, dusted, glazed, and dried in a hot drying-room. These processes vary as different kinds of powder are wanted. In the last few years there have been many improvements in firearms, and with these changes has arisen a demand for new varieties in gunpowder — especially for smoke-