What artillery concept did Leonardo da Vinci arrange in three rows to allow continuous firing?

Leonardo da Vinci arranged a 33-barrel organ in three rows to allow repeated artillery fire.

The design placed thirty-three small cannons on a frame, divided into three rows. While one row fired, the other rows could be reloaded or allowed to cool. The arrangement was intended to improve the practical rate of fire compared with a single cannon.

The name organ gun comes from the visual resemblance between the parallel gun barrels and the pipes of a musical organ. Leonardo’s design was not a machine gun in the modern sense: it did not use cartridges, automatic loading, or continuous mechanical firing.

The concept also illustrates a major problem in early gunpowder warfare. Firing many barrels could increase firepower, but smoke, recoil, reload time, and the difficulty of aiming remained serious limitations. Leonardo’s sketch was therefore an engineering proposal rather than evidence of a successful battlefield weapon.