What type of lock did Leonardo da Vinci design for canals and waterways?

Leonardo da Vinci designed a miter lock for canals and waterways.

A miter lock uses two gates that meet at an angle pointing upstream. Water pressure pushes the gates together, helping them seal when the level differs between the two sides. Leonardo designed improvements to canal locks, including gates and arrangements intended to make navigation and water control more efficient.

The design belongs to civil engineering rather than to a weapon or flying machine. Leonardo worked on canal projects in northern Italy, especially around Milan, where locks allowed boats to overcome changes in elevation. The general miter-gate principle existed before Leonardo; his importance lies in refining and applying engineering solutions.