A machine gun is an automatic weapon that is capable of a rapid rate of sustained fire.
The predecessor to the modern machine gun was developed in 1718, by James Puckle, an Englishman. This gun, known as the "Puckle gun", could fire around nine bullets per minute. However, the Puckle gun was a flintlock weapon, and cannot be considered a machine gun in the modern sense of the word.
With the development of preloaded cartridges auto-repeating guns were quickly developed. The first modern machine gun was the Gatling gun, a crank-operated weapon capable of firing over a hundred rounds per minute. It was invented for use in the American Civil War. Though relatively easy to use, the barrels would soon overheat with successive volleys and the mechanism jammed. This type of machine gun used a magazine that could hold 20 to 50 rounds of ammunition.
The first automatic machine gun was the Maxim gun, invented by Hiram Maxim. The Maxim gun used the recoil energy of the round fired to operate the reloading mechanism. The Maxim gun also saw the first use of a coolant system, in the form of a water jacket; the barrel of the gun was surrounded by a "jacket", or sheath filled with water. In addition, the ammunition was fed into the block mechanism by means of a continuous metal belt, several of these belts could be linked together to enable a sustained rate of continuous fire. These improvements greatly increased the sustained fire time of the gun. Maxim was an American inventor who lost some patent battles with Thomas Edison on the light bulb and other inventions, and was persuaded to move to Europe and make improvements to weaponry there.
The gas-operated machine gun, which uses gas pressure vented from the barrel during firing to operate the reloading mechanism, was invented several years later by American inventor John Browning. Browning introduced this new principle in the Model 1895 Browning 'potato digger' machine gun.