Leonardo da Vinci improved the canal miter lock, which uses paired gates that meet at an angle.
In a miter lock, two gates close in a V shape pointing toward the higher water level. Water pressure pushes the gates against their meeting point, helping them remain shut. The lock chamber can then be filled or emptied so boats can travel between different water levels.
Leonardo worked on canal engineering in northern Italy, especially around Milan. His designs for canal gates and water-control systems helped refine ways to manage navigation through uneven terrain. The principle is especially associated with the Navigli canal network, although the broader development of miter gates involved earlier engineering traditions as well.
A miter lock is not an aqueduct or a simple weir. An aqueduct carries water across a gap, while a weir controls flow by holding back water. A navigation lock changes a boat’s elevation by regulating the water level inside a chamber.