steamgun

A gun whose projectile force is derived from the expansion of steam i uing through a shotted tube. steam-hammer, s. Mech.: A hammer worked by means of steam. The idea of a steam-hammer seems to have occurred first to James Watt, who patented it in 1784. William Deverell also took out a patent for a steam hammer in 1806; but it does not appear that in either case the idea was carried into operation. In 1839 James Nasmyth invented the steam-hammer called after him, and patented it in 1842. In the older forms of steam-hammer, the hammer-head, attached to one end of a lever, was raised by the action of a cog-wheel or cam acting on the other end of the lever, and was then allowed to fall by its own weight. Hammers of this description are often called Steam-tilts. In Nasmyth's hammer, the head is attached to the piston-rod of an inverted cylinder supported vertically, and the piston is raised by the action of the steam admitted into the cylinder below the piston. The hammer is allowed to fall by its own weight, or is driven downward with still greater velocity by the action of steam admitted into the cylinder above the piston. The admi ion of steam into the cylinder is regulated by a slide-valve worked by a lever, and the force of the stroke can be controlled to such an extent by regulating the admi ion of steam, that the largest hammer can be made to crack a nut, or to come down upon a ma of iron with a momentum of many hundred foot-tons. The cylinder, which is supported on a strong iron framework, is very strong, and the steam-pipes are of extra strength, because of the high pre ure at which the steam is employed. The piston-rod is of stout wrought-iron or steel, and the hammer itself is also of steel. The weight of the hammer ranges from about two hundred-weight to twenty-five tons; and the object to be struck is placed upon an anvil, consisting of a slab of iron, resting on a huge ma of piles and concrete, which frequently descends a great depth into the ground. There are some other forms of le importance. In Condie's steam-hammer the hammer-head is attached to the lower end of the cylinder, and Rams bottom's two cylinders move horizontally in the same line, but in different directions, and the metal to be forged is placed between them. Steam-hammers are rated or cla i fied according to the effective weight of the piston and hammer-head or drop, and range from 100 IMG:content-0249.png:[blocks in formation] IMG:content-0250.png:[blocks in formation]