Leonardo da Vinci designed a miter lock with hinged gates to control canal water levels.
While working on Milan's canal system, Leonardo studied lock gates that could separate sections of water at different elevations. Miter gates meet at an angle pointing upstream; water pressure pushes them together, helping seal the opening. This arrangement made it possible for boats to pass between canal levels without draining an entire canal section.
Leonardo is often credited with improving canal-lock engineering rather than inventing every principle from nothing. His work on the Naviglio di San Marco included designs for practical gates and hydraulic systems. The lock should not be confused with a floodgate or a simple sluice: a navigation lock raises or lowers vessels through a controlled water chamber.