Two hundred years ago, Richards, a London gunsmith, converted the ancient wheel-lock into the flint-lock; he also rifled his barrel and loaded it at the breech. The Richards weapon was double-barrelled, and unscrewed for loading at the point where the powder-chamber ended; the ball was placed in this chamber in close contact with the powder, and the barrel rescrewed. The bullet being a soft leaden ball, was forced, when the charge was fired, through the rifled barrel with great accuracy of aim. The percussion cap did not oust the flint-lock till less than a century ago, when many single-barrelled pistols, such as the famous Derringer, were produced; these in their turn were replaced by the revolver which _Colt_ introduced in 1836-1850. Smith and Wesson in the early sixties improved upon it by a device for extracting the empty cartridges automatically. Livermore and Russell of the United States invented the “clip,” containing several cartridges; but the equally well-known _Winchester_ has its cartridges arranged in a tube below the barrel, whence a helical spring feeds them to the breech as fast as they are needed. At the present time each War Department has its own special service weapon. The German _Mauser_ magazine-pistol for officer’s use fires ten shots in ten seconds, a slight pressure of the trigger setting the full machinery in motion; the pressure of gas at each explosion does all the rest of the work--extracts and ejects the cartridge case, cocks the hammer, and presses springs which reload and close the weapon, all in a fraction of a second. The _Mannlicher_ is of the same automatic type, but its barrel moves to the front, leaving space for a fresh cartridge to come up from the magazine below, while in the Mauser the breech moves to the rear during recoil. The range is half a mile. The cartridges are made up in sets of ten in a case, which can be inserted in one movement. MACHINE-GUNS. Intermediate between hand-borne weapons and artillery, and partaking of the nature of both, come the machine-guns firing small projectiles with extraordinary rapidity. Since the United States made trial of Dr. Gatling’s miniature battery in the Civil War (1862-1865), invention has been busy evolving more and more perfect types, till the most modern machine-gun is a marvel of ingenuity and effectiveness.