Leonardo da Vinci designed improvements to canal locks for controlling changing water levels.
His notebooks contain studies of lock gates and canal engineering, especially during his work in Milan and the Lombardy waterway system. A lock lets a boat move between stretches of water at different elevations by filling or emptying a chamber between gates. Leonardo refined features such as mitre gates and arrangements for managing water flow.
Leonardo is sometimes credited with inventing the canal lock, but that claim is too broad. Earlier pound locks existed in China and Europe, and working locks were already being developed in northern Italy. His contribution was chiefly the design and improvement of mechanisms used in canal navigation.
The subject is closely tied to Leonardo's practical engineering career. He worked on canals, irrigation, drainage, and flood-control proposals, treating water as both a useful resource and a force that had to be carefully directed.