Page:Collier's New Encyclopedia v. 01.djvu/357

LEFT ABTILLBRY 285 ABTILLERY Shrapnel therefore has been largely sup- planted by a grenade which pierces the envelope and explodes inside, thus set- BRITISH 6" ANTI-AIRCRAFT GUN ting the balloon in flames. The trail of the grenade is made by a special smoke that accompanies the projectile by day and leaves a faint w^hite wake at night. In this way the gunner is able to see how nearly he has to come to the mark. In the case of field guns, the caliber is 2.6 11" SUTTON TRENCH MORTAR AND PROJECTILE and the projectile weighs 9 pounds. For the gun mounted on a motor car the cal- iber is 3-inch and the projectile weighs 12 pounds, leaving the muzzle with a ve- locity of 2,060 feet per second. The range is about 6 miles and the height attained is nearly 4 miles. The trench mortars were valuable chiefly for the work at short distances when the opposing armies faced each other over No Man's Land. Because of their mobility, they were useful in accompanying the drives that both sides at times inaugurated, because they could be set up rapidly in newly acquired positions. Great quantities of them were used in connection with the German drive of March, 1918. Machine guns (q. v.) have claims to be classed as artillery, although mostly they were used as the personal weapons of the individuals that handled them. They had never before been used in such almost incalculable numbers. In its broadest sense, "Artillery" includes all those forms of weapons and their appurtenances that are de- signed for projecting missiles at an enemy. Technically speaking, however, as has been already stated, it ap- plies only to guns from which pro- jectiles are throvsTi by the explosive force of gunpowder. In this narrow sense, its history naturally begins with the invention of gunpowder. Ckins. — Essentially a gun is a tube, closed at one end, into which are loaded a charge of gunpowder and a projectile, with some arrangement for igniting the powder. As the powder burns, it is converted into gas and exerts a pressure which drives the projectile down the bore and projects it at high velocity from the muzzle. Guns are commonly designated by their caliber; as "3-inch," "12-inch," etc., the "caliber" being the diameter of the bore and of the projectile. Excluding shoul- der pieces and machine guns, which are not within the scope of this article, guns of the present day range from 3 to 16 inches in caliber; the 16-inch, the most powerful gun in existence in 1921, having been designed especially for the armament of the United States battle- ships of the 1920 class. The guns in use up to the middle of the last century were of cast iron or THE RODMAN 10" GUN, USED IN THE AMERICAN CIVIL WAR bronze, cast in a single homogeneous mass around a core. They were "smooth- bored" and "muzzle-loading" and fired