Leonardo da Vinci placed 33 barrels on his multi-barrel organ gun design.
The device arranged many small cannon barrels in a fan-shaped row. It is often called a 33-barrel organ or organ gun because the barrels resembled the pipes of a musical organ. The arrangement was intended to fire a broad volley and then allow one row to cool while another row was used.
Leonardo presented the concept in the context of military engineering. Unlike a single cannon, a multi-barrel weapon could increase the number of shots delivered in a short interval, although loading, aiming, recoil, and transportation would have posed major difficulties.
The design should not be confused with a modern machine gun. It was a muzzle-loading artillery concept, and there is no reliable evidence that Leonardo's particular drawing became a deployed weapon. Its importance lies in the way it combined repeated fire with a rotating or staged firing arrangement.