Leonardo da Vinci improved the canal lock by using a pair of mitre gates.
Mitre gates meet at an angle pointing upstream, so water pressure helps press them shut. Leonardo applied this principle to canal engineering while working on waterways in northern Italy. A lock allows boats to move between sections of water at different elevations by filling or emptying a chamber.
Leonardo’s canal work is strongly associated with the Naviglio system around Milan. His studies examined water flow, gates, channels, and methods for making navigation more efficient. The mitre-gate principle became a standard feature of later canal locks.
A canal lock is not an aqueduct. An aqueduct carries water across a valley or obstacle, while a lock changes a vessel’s level. Leonardo also designed many hydraulic machines, so individual sketches should not be treated as proof that he invented every component from scratch.