Leonardo da Vinci designed a miter lock using interlocking gates to control canal water levels.
A miter lock has two gates that meet at an angle pointing upstream. Water pressure pushes the gates together, helping them seal the opening when the water level differs on the two sides. By filling or emptying the enclosed chamber, boats can pass between stretches of canal at different elevations.
Leonardo worked on canal engineering in Milan, where waterways were important for transport, irrigation, and construction. His improvements included detailed studies of lock gates and mechanisms for managing water flow. The Milanese canal system provided a practical setting for his engineering interests.
Leonardo did not invent the entire idea of water locks from nothing, and earlier forms existed. His importance lies in developing and refining designs for reliable canal operation. A miter lock should not be confused with a simple sluice, which regulates water flow but does not raise or lower boats between canal levels.