Leonardo da Vinci designed an organ gun with 33 small-calibre barrels.
The weapon arranged its barrels in three rows of eleven. The structure could be loaded while another row was being fired, allowing a more continuous sequence of shots than a conventional single-barrel gun of the period.
Leonardo’s design was called an organ gun because the parallel barrels resembled the pipes of a musical organ. It was a proposal rather than a confirmed battlefield weapon, and surviving evidence does not show that Leonardo successfully built and operated the complete machine.
The design is sometimes described as an early multiple-barrel firearm or a predecessor of the modern machine gun. Those labels describe its repeating-fire concept, but the weapon relied on manual loading and did not have a modern automatic mechanism.