Leonardo da Vinci designed a mitre lock with interlocking angled gates.
A mitre lock allows boats to move between sections of water at different levels. Its two gates meet at an angle pointing toward the higher water, so water pressure pushes the gates together and helps seal the opening. Leonardo improved and documented this type of canal-lock arrangement during his engineering work in northern Italy.
Leonardo’s canal projects around Milan involved controlling water levels, improving navigation, and managing irrigation. Locks were essential because canals often crossed terrain with changes in elevation. A well-designed lock could admit or release water in a controlled way while keeping a vessel inside the chamber.
The device is not the same as a sluice gate. A sluice controls water flow, while a navigation lock changes a boat’s elevation between water levels. Leonardo did not invent every principle of canal engineering, but his drawings and practical proposals helped refine mechanisms used in Renaissance waterworks. Mitre gates remain recognizable in modern canal infrastructure.