Engineering Wonders of the World
Volume I

THE ARMAMENT OF A BATTLESHIP. 409 continuous movement, first rotates and un- locks the breech-plug, and then swings the entire mass clear of the gun, leaving it ready for sponging out and for the insertion of another shell. The time required for open- ing the breech of a modern 12-inch gun is 3- 9 seconds by mechanical gear, and 6 seconds by hand ; for shutting, 4- 5 and 7 seconds respectively. The backward force of the explosion of the powder charge within the bore itself is taken up by what is called an “ obturator ”—a plastic pad of asbestos or similar material protected by metal rings, seated in a cone formed at the rear of the powder chamber, and secured to the breech- screw by means of a mushroom-headed bolt and nuts. In it is arranged the electrical firing device explained below. The Mark IX. gun carried by the King Edward VII. weighs 50 tons without its mounting, and is 496| inches long over all. The length of the bore, or Latest rifled part of the barrel, is 40 ■ 2^inchS Gun. feet' The oordite charge weighs 211 lbs., the shell 850 lbs. The speed at which this mass of metal leaves the muzzle is 2,580 feet per second, and the energy at the muzzle in foot-tons is 39,280, or more than sufficient to lift two Dreadnoughts a foot off the ground. The power of this piece of ord- nance may be measured by penetration. It is calculated that at the muzzle this gun would drive its shell through 42 inches of wrought iron ; at 3,000 yards through 32 inches of the same metal. This gun led the world four years ago ; yet since then we have had the Mark X., 45 calibre gun, and have already passed it by for the Mark XI. of 50 calibres. The Mark XI. weighs 65 tons 17 cwk without its mounting, and is 617f inches long. The bore has a length of 600 inches, or 50 feet; and though the weight of the shell remains at 850 lbs., the cordite charge has increased to 344 lbs. The velocity of the projectile at ROUNDS PER MINUTE. 2 - 12 m WEIGHT OF METAL DISCHARGED = 1700 /bo eftfeM 4- - 9-2 In 8 - 10 - 12 - 15 - 29- fSin 6 in, II ini niiiiii ■=. 160 O /bs of Meltl HHIIIHI = lOOOlliSofMttål 114-0 Ihs ofMcM ' iiiiiiiiiiii = S4- 0 lbs of MeM j;,« HltlllllliiiimiääiHH ' DIAGRAM SHOWING NUMBER OF ROUNDS FIRED AND WEIGHT OF METAL DISCHARGED PER MINUTE BY GUNS OF VARIOUS CALIBRES. the muzzle is 3,010 feet per second, and the muzzle energy has been, augmented to 53,400 foot-tons. The most noticeable difference, however, is in. the muzzle penetration of wrought iron, which lias now risen from 42 inches to 52’1 inches—an immense advance. It is calculated that this weapon has a maximum range of 25 to 27 miles. The stupendous recoil of a modern gun is absorbed most wonderfully by a combination of pneumatic and hydraulic resistance cyl- inders placed beneath the gun-carriage. In the latest electrically operated guns the weapons themselves are run out subsequent to the recoil by what is called a “ counter- recoil.” This is either a pneumatic cylinder or a strong battery of springs. Our own Admiralty is making experiments with both systems in the armoured cruiser Invincible. These large guns are placed on their mount- ings in “ cradles ” or steel bearings curved to the circumference of their outer surfaces. Square steel “ thrust rings ” welded to the exterior jacket, ^un . , Mountings, and forming an integral part of it, engage with slots cut in the cradle. When mounted in pairs in barbettes or turrets, guns are designated “ left ” or “ right,”