Page:Popular Science Monthly Volume 51.djvu/168

158 experiments were made before a successful breech-loading mechanism, was perfected. An explanation of either of the two modern systems would be beyond the scope of the present discussion. It



may be sufficient to say that the system in use in America is substantially that of the French, an interrupted screw which fits into the breech and is provided with an efficient gas check. This is so constructed that the mere fact of explosion tightens the gas check and effectually prevents the escape of hot gas between the threads of the screw.

The largest and most celebrated gun factory in the world is that of Krupp, at Essen in Germany, near the Belgian border. Besides monopolizing the construction of guns for the German Government, this factory has supplied a great number to most of the leading powers of Europe. It was established in 1818, and from the very outset attention was concentrated upon the making of steel. The first finished piece of artillery in cast steel was made in 1847. This was a small field gun capable of projecting a ball of only three pounds. The manufacture of steel at these works has since been so perfected that Krupp can now be scarcely said to have an acknowledged rival in the world. His magnificent display at the Chicago Exposition was seen and admired by many thousands of visitors. Among these exhibits was a steel rifle forty-two centimetres (16·54 inches) in caliber, and thirty-three calibers (forty-six feet) in length. Its weight is one hundred and twenty tons, or a little more than double that of the twelve-inch rifle at Watervliet. With a charge of nine hundred pounds of powder it gives an initial velocity of two thousand feet per second to a projectile weighing twenty-two hundred pounds, whose initial energy is thus sixty thousand foot tons. When fired at an elevation of about eleven degrees it sends this projectile to a