Leonardo da Vinci sketched an organ gun with 33 small gun barrels arranged in three rows.
The design is commonly called a three-barrelled organ gun, or a volley gun. Its barrels were mounted on a wheeled frame and arranged like the pipes of a musical organ. The arrangement was intended to fire a broad volley, then allow another row to be prepared while the first cooled or was reloaded.
The weapon was part of Leonardo’s military engineering work, much of which he presented to powerful patrons such as Ludovico Sforza. It remained a design rather than a famous battlefield weapon, and there is no reliable evidence that Leonardo’s exact model was deployed.
An organ gun is different from a machine gun. It has multiple fixed barrels and fires volleys, whereas a machine gun normally uses one or more mechanisms for sustained, rapid fire. Leonardo’s design also differs from a conventional cannon because its striking feature was the grouped arrangement of many smaller barrels.