What canal device did Leonardo da Vinci improve with mitre gates?

Leonardo da Vinci improved the design of a canal lock by using mitre gates.

A canal lock raises or lowers boats between stretches of water at different levels. It consists of a chamber with gates at both ends: the boat enters, the gates close, and water is added or released until the water level matches the next section of canal.

Leonardo worked on canal engineering in Milan, especially during projects connected with the Naviglio system. His designs included paired gates meeting at an angle, now called mitre gates. Water pressure pushes the angled gates together, helping them seal when the chamber contains water.

Leonardo did not invent canal locks or the general idea of gates meeting in a V shape. Earlier forms existed, including systems in Renaissance Italy. His importance lies in his detailed engineering studies and improvements to practical canal machinery. The term canal lock is more precise here than “sluice,” because a lock changes a vessel’s elevation rather than merely controlling water flow.