Barrel of Gatling gun, c1872. Diagram detail of the cyclic multi-barrel Gatling gun, an early form of rotary cannon. Invented by Richard Gatling and patented in 1862, the Gatling was a rapid-fire spring loaded, hand cranked weapon which allowed higher rates of fire to be achieved without the barrels overheating. From "The Franco-Prussian War: its causes, incidents and consequences", Volume I, by Captain H M Hozier. [William Mackenzie, London, 1872]