The 8-inch Krupp is now included among her heavy guns, and in Cuba she has in service a great many large American cannon, Parrott rifles and Rodman smooth-bores. Belgium has Krupp fours and sixes with calibres of 3 and 3.5 inches; her heavy guns are on the same system. The Krupp field guns are also used by Turkey, Rou-mania, and Servia, as well as in China and Japan. Switzerland, after adopting in 1862 rifled muzzle-loaders, exchanged them in 1866 for steel breech-loaders. The Swedish, Dutch, and Danish governments, like the French, construct their large rifles of cast iron hooped with steel; some of them have shown great endurance, a Swedish rifle, it is said, having been fired 1,100 times. - In the United States cast-iron cannon attained an unrivalled degree of perfection. Gen. Rodman's model, which does not materially differ from that of 1858, was adopted in 1860 for all seacoast. cannon; the exterior shape is remarkable for its simplicity and relative lightness, the parts being proportioned with reference to the exact amount and locality of the strain, to the entire neglect of the merely ornamental or traditional.

Rodman's method of hollow casting having, in conjunction with his big-grained powder, obviated the main difficulties in making very large cast-iron can- non, a 15-inch gun weighing 50,000 lbs. was successfully cast in 1860, followed in 1863 by a 20-inch gun weighing 115,000 lbs. and firing a 1,080-lb. solid shot. The Rodman smooth-bores | are the 20, 15, 13, 10, and 8-inch, the last two being but temporarily retained in service until replaced by heavier guns; only two 20 and two 13-inch guns have been made for experimental purposes, but they have given favorable results. A large number of 15-inch Rodmans are now in service; the shell weighs 330 lbs., the solid shot from 440. to 425 lbs., the service charge being 100 lbs., which will give an initial velocity of 1,500 feet. The accuracy of the gun at 1,500 yards is as great as that of any rifle; its trajectory within this distance is flatter, and the projectile being round has greater precision in ricochet fire. On the other hand, rifles can project loaded shells of peculiar construction so as to penetrate and then explode in the object; their projectiles do not lose their velocity as soon as those of smooth-bores, so that they are more effective at long ranges; while if made of wrought iron or steel, though far more costly, they have much greater endurance than cast-iron guns.

The experimental Rodman cast-iron rifles, 12 and 8-inch, the former having the exterior form of the 15-inch smooth-bore, were found not to possess the requisite strength, and the United States is now (1873) about to experiment upon several other systems of rifled cannon, with a view to the adoption of that found most advantageous. The 20, 15, and 13-inch, and of late the 11-inch, naval guns have the Dahlgrcn exterior shape, but are cast hollow with the Rodman elliptical chamber. A 3-inch rifle muzzle-loading wrought-iron gun was adopted in 1801; it is made by wrapping boiler plate about an iron bar so as to form a cylindrical mass, which is brought to a welding heat in a furnace, and then passed between rollers to thoroughly unite it; the trunnions are afterward welded on and the piece bored and turned to the proper size and shape, the latter being of the general character of the Rodman pattern. Its weight is 820 lbs., that of the projectile being only 10 lbs., in which respect it does not compare favorably with the Prussian, Russian, and Austrian fours, which fire a much heavier projectile in proportion to the weight of the piece.

The 4 1/2-inch rifle is similar in shape to the 3-inch, and was adopted about the same time: it is of cast iron cooled from the exterior, its weight being 3,450 lbs., that of the projectile 30 lbs., while the Russian nine, which only weighs 1,382 lbs., fires a 31 1/4- lb. projectile. Though intended for siege and garrison purposes, it has been used with an army in the field in spite of its want of mobility. The ! Parrott muzzle-loading rifles are cast-iron pieces of ordinary dimensions, strengthened by shrinking a wrought-iron hoop or barrel over that portion of the reenforce which surrounds the charge; the cast-iron body in the larger calibres is hollow-cast on the Rodman plan; the barrel is shrunk on by the aid of heat, the cast iron being prevented from expanding by a stream of cold water made to run through the bore. Parrott guns consist of 300, 200, 100, 30, 20, and 10-pdrs., the diameter of the bores being respectively 10, 8, 6.4, 4.2, 3.67, and 3 inches, and weights of projectiles 250, 150, 86, 28, 19, and 10 lbs. This system has not been adopted by the United States government, though a great many Parrott rifles were used during the civil war, and a certain number of guns of the larger calibres are still temporarily retained.

While some Parrott cannon have shown very great endurance and been largely used in breaching masonry and other siege operations, a number have burst, particularly in the navy, the accidents being mainly ascribed to the breaking and wedging of the projectile in the bore; the inventor, however, now asserts that he has corrected this evil. At the beginning of the war a number of old 42 and 82-pdrs. were rifled on the Parrott system for temporary use, and served with projectiles of twice the weight of the corresponding round shot; the 42-pdrs. only were hooped. The Brooke gun, made and used by the confederates, is very similar to the Parrott in shape and construction, except that the hoop is made of wrought-iron rings not welded together. King's counterpoise gun carriage, recently tried in the United States, was found to excel Mon-crieff's in strength and simplicity, while giving equal protection to the piece and cannoneers. The counterpoise, connected with the top carriage by ropes and pulleys, is placed in a well made in the parapet opposite the gun; the chassis slopes considerably to the rear, so as to form an inclined plane for the descent of the piece and top carriage; as the recoil forces them back and down, the counterpoise rises in the well until its weight suffices to bring the piece to rest behind the parapet.