Leonardo da Vinci designed a miter lock to help boats pass between canals at different heights.
A miter lock uses two gates that meet at an angle pointing upstream. Water pressure pushes the gates together, helping them seal the opening. By filling or emptying the lock chamber, boats can be raised or lowered between water levels without draining an entire canal section.
Leonardo worked on canal engineering in northern Italy, especially around Milan, where navigation routes had to overcome changes in elevation. His notebooks include studies of lock gates, channels, and water control. The miter-gate principle was not invented solely by Leonardo, and earlier canal systems had already used water-level management. His contribution was to analyze and refine mechanisms within a broader tradition of hydraulic engineering. The term “miter lock” identifies the gate arrangement, while the complete lock also requires a chamber and controlled openings for water.