What weapon did Leonardo da Vinci design with 33 small-caliber guns arranged in three rows?

Leonardo da Vinci designed a 33-barrel organ with 33 small-caliber guns arranged in three rows.

The weapon appears in Leonardo’s military engineering studies. Its barrels were mounted on a wheeled frame, and the rows could be fired in sequence. The name “organ” refers to the visual arrangement of many barrels, which resembles the pipes of a musical organ. Leonardo’s design aimed to combine a broad volley with a mechanism that could be reloaded while another row was in use.

The device was a proposal, not a confirmed battlefield weapon built and used by Leonardo. It is sometimes loosely called a machine gun, but that label can mislead because the design depended on separate gun barrels and sequential firing rather than modern automatic operation. The 33-barrel arrangement is the specific feature that distinguishes this invention from Leonardo’s other artillery sketches.