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 thrown by the explosive force of gunpowder. In this narrow sense, its history naturally begins with the invention of gunpowder.
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 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 bronze, cast in a single homogeneous mass around a core. They were bored" and "muzzle-loading" and fired a spherical shot or shell weighing per haps 10 per cent. of the weight of the elongated projectile of a modern gun of the same caliber. About 1850, General
P. 5. Rodman, of the United States Army, conceived the idea of increasing the strength of guns by casting them with a hollow core through which a stream of cold water was kept flowing. The effect of this was to produce a varying tension in the successive layers of metal from the inside out, so that the walls of the gun acted as a whole in resisting the pressure of the powder when the gun was fired. This principle, of "varying initial tensions," is applied in modern guns by building up the walls in successive layers of steel hoops, shrunk, one upon another, over a central tube. Figure 1, Plate A. The tube is pierced throughout its length to form the bore, which is rifled by grooves running spir ally from breech to muzzle. The projec tile, which is cylindrical with a pointed head, carries at its base a ring of soft copper, which, when the gun is fired, is forced into the grooves of the rifling and sets the projectile spinning with great velocity as it is driven along the bore. It is this spinning that keeps the pro jectile true in flight and makes possible the long ranges and great accuracy at tained by modern artillery. The gun is fired by a primer through a vent in the breech plug.
The practical development of the rifled gun of large caliber as an actual and important factor in warfare dates from about 1855, although the principle involved had long been familiar to ar tillerists and had been applied experi mentally as early as 1745. Built-up guns came into use at about the same time (1850-1860), and the combination of these two factors resulted in the de velopment of the high-powered, built up, rifled gun, which, in the last half of the 19th century, practically revolu tionized artillery, especially naval artil lery, and, in association with smokeless powder—perfected about the end of the century—may be held to have practi cally revolutionized warfare.