What multi-barrel firearm did Leonardo da Vinci design with three rows of gun barrels?

Leonardo da Vinci designed the 33-barrel organ, a multi-barrel firearm arranged in three rows.

The machine was intended to fire many small cannon or gun barrels in sequence. Its name comes from the organ-like arrangement of the barrels rather than from musical function. A frame could be loaded and aimed, while the rows allowed one group to fire as another was prepared.

Leonardo’s design addressed a practical problem in early gunpowder warfare: the slow reload time of individual weapons. Multiple barrels could increase the volume of fire and reduce the delay between volleys. However, there is no secure evidence that Leonardo’s exact design was manufactured and used in battle.

The device is often called a machine gun, but that modern label can be misleading. It was a manually operated volley weapon, not a self-loading firearm. It also differed from a conventional cannon because it combined many smaller barrels in one carriage.