Leonardo da Vinci designed an organ gun with multiple barrels fired in sequence.
An organ gun, also called a ribauldequin in some historical contexts, groups several small gun barrels on a frame. Leonardo’s design arranged barrels so that a crew could fire a volley and then prepare another group, increasing the rate of fire compared with a single cannon. The weapon’s name comes from the visual resemblance between its parallel barrels and the pipes of a musical organ.
Leonardo included multi-barrel artillery among his military-engineering ideas. These designs still depended on gunpowder, loading, aiming, and crew coordination, so they were not equivalent to modern automatic weapons.
The common mistake is to call Leonardo’s organ gun a machine gun. A machine gun fires repeatedly through a modern loading and firing mechanism, while an organ gun is a manually operated group of separate barrels. Leonardo’s proposal belongs to the development of volley artillery.