What instrument did Leonardo da Vinci design with 33 gun barrels arranged side by side?

Leonardo da Vinci designed a 33-barrel organ with gun barrels arranged in three rows of eleven.

The device was a volley gun: multiple small cannons were mounted on a wheeled frame so they could be loaded and fired in sequence or together. Leonardo proposed the arrangement to increase the speed and regularity of artillery fire compared with repeatedly loading one cannon.

The word “organ” refers to the visual resemblance between the parallel barrels and the pipes of a musical organ, not to a musical function. The weapon was also intended to be repositioned more easily than many heavy artillery pieces. Leonardo’s drawings show both the barrel arrangement and a carriage designed for battlefield use.

It is often called Leonardo’s machine gun, but that label is modern and potentially misleading. The weapon still relied on gunpowder and individual cannon barrels; it did not use the continuous mechanical firing system of a modern machine gun.