Leonardo da Vinci helped develop the miter lock, a canal lock using angled gates that press together under water pressure.
In a miter lock, two gates meet at an angle pointing upstream. Water pressure pushes the gates toward their central seam, helping them seal rather than forcing them open. This arrangement allows boats to move between water levels while limiting the amount of water released at once.
Leonardo worked on canal engineering in northern Italy, where locks were important for navigation and water management. His designs and improvements are associated with the canal system around Milan, including work connected with the Naviglio Grande and other waterways.
Leonardo did not invent every part of the canal lock from nothing. Earlier forms of locks existed, and the miter-gate principle has a longer engineering history. His importance lies in studying, improving, and applying hydraulic structures with unusual attention to their mechanics and operation.