Leonardo da Vinci designed a miter lock for canals to manage changing water levels.
A miter lock uses two gates that meet at an angle, usually pointing upstream. Water pressure pushes the gates together, helping them seal when the water levels differ. Boats can pass between chambers while the water level is raised or lowered in a controlled way.
Leonardo developed canal-lock ideas while working in northern Italy, where canals supported transport, irrigation, and urban water management. His improvements included stronger gate arrangements and mechanisms intended to make filling and emptying lock chambers more practical. The Naviglio di San Marco in Milan is associated with canal works attributed to Leonardo’s engineering activity.
Leonardo did not invent the general principle of canal locks, which existed before his work. His importance lies in studying and improving their mechanisms. A sluice gate controls water flow, but the characteristic paired, angled doors in this design are miter gates.