Leonardo da Vinci improved the canal miter lock by using hinged gates that meet at an angle.
A miter lock has two gates whose inner edges meet in a V shape pointing toward the higher water level. Water pressure pushes the gates together, helping them resist the force of the water. Leonardo’s canal work in Milan included improvements to lock gates and related hydraulic engineering.
The design made it easier for boats to move between waterways at different elevations. By closing the gates and changing the water level inside the chamber, a vessel could rise or descend without draining an entire canal section.
Leonardo did not invent the basic concept of canal locks, and earlier examples existed in China and Europe. His importance lies in refining practical hydraulic details and applying geometry, mechanics, and water-flow observation to canal infrastructure.