What artillery design by Leonardo da Vinci used many barrels arranged in rows?

Leonardo da Vinci designed a 33-barrel organ, a multi-barrel artillery concept.

The weapon used 33 small cannons arranged in three rows of eleven. Its layout was intended to increase the rate of fire compared with a single cannon: one row could be fired while another was being reloaded.

The name organ gun comes from the visual resemblance between the aligned barrels and the pipes of a musical organ. It was not a musical instrument, despite the name, and it should not be confused with the later hand-held organ gun or ribauldequin family in general.

Leonardo’s design remained a concept rather than a clearly documented, battlefield-standard weapon built by him. Its significance lies in applying repeated barrels and staged firing to an artillery problem.