Leonardo da Vinci designed a mitre lock to control changing water levels in a canal.
A lock allows boats to move between sections of water at different elevations. Leonardo is credited with developing the mitre-gate form, in which two gates meet at an angle pointing toward the higher water level. Water pressure pushes the gates together, helping them resist the force when the lock is closed. This made canal navigation more practical in uneven terrain.
Leonardo worked on canal and hydraulic projects in northern Italy, including schemes connected with Milan. The mitre lock is sometimes confused with a simple sluice gate, but a lock has a chamber between gates and changes a vessel’s elevation step by step. Leonardo did not invent the general idea of raising boats through chambers; earlier water-control systems existed. His importance lies in improving a gate arrangement that became fundamental to canal engineering.