What machine did Leonardo da Vinci design with 33 barrels arranged like organ pipes?

Leonardo da Vinci designed the 33-barrelled organ, a multi-barrel gun with 33 barrels arranged in three rows.

The weapon appeared in Leonardo’s military designs from the late fifteenth century. Its barrels were mounted on a wheeled frame and arranged in groups, allowing a volley of shots to be fired in succession. The nickname “organ” comes from the visual resemblance between the parallel barrels and the pipes of a musical organ.

The concept was intended to improve the rate of fire of small cannons. While one row was firing, another could be loaded, theoretically reducing the long pauses common with heavy gunpowder weapons of the period. It was not a modern machine gun, because each barrel still required separate loading and ignition.

Leonardo’s multi-barrel design reflects his interest in practical battlefield engineering. It belongs to the same broader body of military work that included armored vehicles, bridges, fortifications, and large crossbows. The surviving sketches show concepts, not evidence that every weapon was built or used in combat.