What type of lock did Leonardo da Vinci improve for canals?

Leonardo da Vinci improved the canal miter lock, whose paired gates meet in a V-shaped point against the water pressure.

A lock allows boats to move between water levels by filling or emptying a chamber. Leonardo worked on canal engineering in northern Italy and is associated with refinements to the miter-gate arrangement. When the chamber is higher on one side, the water pressure pushes the two gates tightly together at their angled meeting point, helping them seal.

Leonardo's canal work included surveys, water-control ideas, and proposals connected with Milan's waterways. The miter gate itself was not simply invented from nothing by Leonardo; related gate forms existed before his work. His contribution is better understood as an important refinement and application of canal-lock engineering. This distinction matters because Leonardo frequently improved existing mechanisms rather than creating every device entirely from scratch.