Leonardo da Vinci improved the canal lock with a hinged miter gate.
In Renaissance Milan, Leonardo worked on hydraulic engineering for canals, including the Naviglio system. His notes and designs show detailed attention to gates, water levels, and the movement of boats between sections of canal. A lock allows a vessel to move between different elevations by filling or emptying a chamber.
The miter gate design uses two gates that meet at an angle pointing toward the higher water level. Water pressure pushes the gates together, helping them seal the opening. Leonardo did not invent every part of the canal lock, but he refined and documented hydraulic mechanisms with unusual precision for his time.
This invention is sometimes incorrectly attributed entirely to Leonardo. Canal locks existed before his work, and earlier European engineers had already developed important forms of them. Leonardo’s contribution was especially significant in the study and improvement of Milan’s canals, where locks made navigation possible across changing terrain. The system connected waterways used for transport, construction, and agriculture.