The first built-up guns were of wrought iron, but this was soon re placed by steel, the manufacture of which was greatly improved through the demands of artillerists for a combina tion of elastic and tensile strength never before considered possible. The leader in the manufacture of the new guns on a commercial scale was the English met allurgist Sir William Armstrong.
In Germany, Krupp used steel at an early date, but was behind Armstrong in adopting the built-up system. The first modern gun in the United States was built about 1880, but the manu facture on a large scale was not under taken until several years later, when the great steel plant at Bethlehem was established through the influence, and to meet the demands, of the navy. By 1917, when the United States entered the World War, the manufacture of ord nance by Bethlehem and other establish ments and especially by the Naval Gun Factory at Washington, had so far pro gressed that more than three thousand guns of all calibers, with their mounts and ammunition, were turned out in little more than a year.
As used on shipboard, guns of the larger calibers—from 10 to 16 inches— are mounted in turrets with elaborate mechanism for handling ammunition, loading, pointing, firing, and controlling the recoil. On shore, these calibers are mounted in fortifications, often on "dis appearing" carriages by which the gun is held behind the shelter of a parapet i until ready for firing, when it is lifted, fired, and automatically returned to shelter by the force of the recoil. The smaller calibers, as used by the army, are mounted on mobile carriages, drawn by men or horses or by automobile trac tors, constituting what is technically known as "field" and "siege" artillery.
Projectiles.—In the long struggle be tween the penetrative power of projec tiles and the resisting power of armor, the projectile appears to have estab lished a permanent advantage, at least under proving-ground conditions, which are admittedly unfavorable to armor. The 16-inch guns with which the 1920 class of United States battleships are armed have power enough at fighting ranges to drive their 2,100-pound pro jectiles through the thickest armor carried by any ship that has up to the present time been proposed.
The Powder Charge.—Modern gun powder, composed of gun-cotton and nitroglycerine, is as different from the powder of fifty years ago as modern guns are from the guns of the same period. Although commonly called "smokeless," it is far from being so, but it produces decidedly less smoke than the old "black" powder, and its force is many times as great. Its essential fea
ture, apart from its force, lies in its "progressiveness," by which is meant that, instead of burning all at once, with a violent explosion, it burns slowly and gives off its gases gradually, thus giv ing the projectile a push rather than a blow—but a push that becomes more and more pronounced as the projectile moves toward the muzzle. In this way it gives a higher velocity to the projectile with much less strain on the gun.
Gun Mounts.—The problem of mount .ng a high-powered gun of large caliber in such a way as to admit of manipulat ing it freely and controlling the tremen dous shock of the recoil is a difficult and complicated one. Figure 2, Plate A, shows three 14-inch guns of the U. S. S. Idaho on a single mount as installed in each of the turrets of the ship. The photo graph shows the three guns firing simul taneously. The power developed by a salvo of this kind would suffice to lift a city skyscraper some four feet off its Monroe, Va., first established in 1823, discontinue% re-established in 1867, dis continued again in 1898, and again re opened in 1900, gives instruction, both theoretical and practical. The artillery regiments of the regular army have each one foot-battery at the school; term of instruction, one year. A school of five for field artillery was opened at Fort Sill in 1911. All of the other important artillery powers have artillery schools, France at Fontainebleau, England at Woolwich, Italy at Natturno, etc.
foundation. Plate B shows one of these guns photographed in a way to illustrate its length, which is a little more than 70 feet. The length of the 16-inch gun previously referred to is about 10 feet greater.
Plate C shows a 14-inch gun on a specially designed railway mount as used at the French front, together with its powder charge and projectile. Five of these guns were used in the last months of the World War and with great effect. They were the most pow erful guns used on either side during the war, either ashore or afloat; and they were designed and built, with their mounts, at the Naval Gun Factory at Washington, and were transported to the front and operated there by officers and men of the United States Navy. The freak gun used by the Germans in their long-range bombardment of Paris had a greater range than these guns, but its projectile weighed only 200 pounds as against 1,400 for the Ameri can gun, and the damage to be antici pated from an explosion of its projectile was not more than 5 per cent. as great.