Leonardo da Vinci designed an organ gun by arranging many small cannons in parallel rows.
The weapon, also called a multi-barrelled gun, used a set of gun barrels mounted on a frame. The barrels resembled the pipes of a musical organ, which explains the name. Firing several barrels in sequence could produce a rapid series of shots, while the frame allowed the weapon to be aimed as a group.
Leonardo’s military notebooks contain designs for different arrangements of multi-barrelled firearms. The goal was not necessarily to fire every barrel at exactly the same instant. Alternating volleys could let one row cool or be reloaded while another row was used.
The organ gun was still a gunpowder weapon, unlike Leonardo’s giant crossbow. It also was not a modern machine gun: it lacked automatic loading, continuous fire, and a self-contained ammunition system. Its historical importance lies in applying repeated-fire thinking to Renaissance artillery.