What rapid-fire weapon did Leonardo da Vinci sketch with multiple barrels?

Leonardo da Vinci sketched a multi-barreled rapid-fire weapon commonly described as a machine gun.

His design arranged many small cannon barrels in rows on a wheeled frame. One row could be fired while another was being prepared, and the frame could be rotated or adjusted to keep the weapon supplied with loaded barrels. The arrangement aimed to increase the rate of fire compared with a single muzzle-loading cannon.

The machine was a theoretical military design rather than a modern automatic firearm. It required manual loading and did not use the automatic operating mechanisms associated with later machine guns. Its practical problems would have included heavy ammunition, smoke, recoil, and the time needed to reload.

It is also called an organ gun because the parallel barrels resemble the pipes of a musical organ. That nickname describes the layout, while “machine gun” emphasizes the intended rapid-fire role.