Leonardo da Vinci’s multi-barrel artillery design is known as an organ gun.
The name refers to the resemblance between its many barrels and the pipes of a musical organ. Leonardo drew arrangements of small cannons mounted together so that several shots could be fired in succession or in a broad volley. The concept aimed to increase firepower while reducing the delay between individual shots.
An organ gun was not the same as a modern machine gun. Each barrel still required loading and firing, and Renaissance gunpowder weapons were difficult to handle, inaccurate by modern standards, and vulnerable to smoke and overheating. Leonardo’s design was an artillery concept rather than a tested rapid-fire weapon.
Leonardo also drew other military machines, including large crossbows, armored vehicles, and siege devices. Those designs are sometimes mixed together in popular summaries, but the multiple-barrel arrangement is the feature that identifies the organ-gun concept.