What repeating-fire cannon design did Leonardo da Vinci sketch with 33 barrels?

Leonardo da Vinci sketched a 33-barrel organ, a repeating-fire cannon design.

The weapon consisted of 33 small-caliber gun barrels arranged in three rows on a triangular frame. The frame could be rotated so one row was fired while another was loaded and a third cooled. The arrangement was intended to increase the rate of fire compared with a single cannon.

The name “organ” refers to the visual resemblance between the parallel barrels and the pipes of a musical organ. It was not a musical instrument. Leonardo’s design belongs to the wider family of organ guns or volley guns, weapons that grouped multiple barrels to deliver repeated or concentrated fire.

As with many of Leonardo’s military drawings, surviving evidence does not show that this exact machine was built or used in battle. Its significance lies in the attempt to solve practical problems of loading, cooling, and sustained fire through mechanical arrangement.