Leonardo da Vinci improved canal locks with a sliding gate system used to control water levels.
While working in Milan, Leonardo studied canals that connected the city with surrounding waterways. His notes and drawings include designs for lock gates, especially arrangements using mitre gates and smaller sliding openings to regulate the flow of water.
A lock allows boats to travel between sections of canal at different elevations. Gates close a chamber, and water is admitted or released until the boat reaches the level of the next section. This made navigation possible across uneven terrain without building an entirely level canal.
Leonardo did not invent the canal lock from nothing; working locks existed before his studies. His importance lies in analyzing and refining hydraulic mechanisms, including gate construction and water control. The Naviglio di San Marco in Milan is associated with canal works linked to his engineering activity.