AIR GUN. An instrument somewhat re sembling a sporting rifle, designed to diseharge darts or bullets by the elastic force of compressed air. As ordinarily made. an air gun etpnsists essentially of ;in air chamber or reservoir, usu ally located in the stook: of a condensing syringe for pumping air into the reservoir, and of a valve operated by a trigger. which admits the compressed air from the reservoir to the barrel behind the bullet. In some weapon, of this sort a prc,,nre of as much as 500 pounds is.. secured in the reservoir. Usually only a portion of the air in the reservoir is used for a single shot, and. therefore, a number of shots may be tired without recharging the reservoir simply by re leasing the pull mu the trigger immediately and thus closing the valve between the reservoir and barrel after a small portion of the air has es This permit,: repeating air guns to be node similar in the mechanism for inserting the bullets to npeating fire-arms. tibviously, the pressure in the reservoir decreases with each dis (•barge of air, and. therefore, each succeeding bullet is discharged with less force than the pre eeding out- At best. the force with which a bullet is discharged from an air gun is much less than is given by gunpowder. Sinnetimes air guns are made in the form of canes or walking slicks, which, like sword canes, are carried for purposes of personal defense in sudden emer gencies. The range of an air !run of the ordinary kind is from 180 to 250 feet. The air gun Was known in France over INN() centuries ago, and the were acquainted with a device which air acted On the short arm of a lever. the longer
arm of which was used to propel a bullet. In 1886 Lieutenant E. L. Zalinski of the United States Army invented a pneumatic gun for throwing projectiles filled with dynamite: and later the was built for the United States Navy and equipped with three of these guns. This vessel was used during the blockade of Santiago Harbor in the Spanish-American War of 1SOS. During the Brazilian civil war of 1893 the ,Victhcroy was equipped with a pneu matic gun 50 feet long and of 15 inches calibre. The conclusions of experience with both sets of guns was that the range of the gun was too small and the accuracy of its fire insufficient to make it a serviceable weapon on shipboard. The Sims-Dudley pneumatic gun used in the last Cuban rebellion is a field piece having a range of from 2600 to 3600 yards. It consists of a lower, or combustion, tube 7 feet long and 4% inches in diameter, and an upper tube, or barrel, 20 feet long and inches in diameter, mounted on a regular field gun carriage. A cartridge inserted into the breech of the combustion chain her. and containing a 7 to 9 ounce charge of smokeless powder, is fired; this compresses the air in the lower chamber so that it passes into the upper tube or barrel behind the projectile and forces it out. The projectile is a light casing filled with explosive gelatine, which is fired by a time fuse, or by a contact fuse upon striking.