What Leonardo da Vinci device was a movable lock gate for controlling canal water levels?

Leonardo da Vinci’s movable canal gate for controlling water levels was a miter lock gate.

Leonardo studied canal engineering and is credited with improving designs for lock gates. A miter gate uses two leaves that meet at an angle pointing upstream. Water pressure pushes the leaves together against their supports, helping the gate resist the force of the water.

Such gates allow boats to pass between sections of canal at different elevations. By filling or emptying the lock chamber, operators raise or lower a vessel without requiring a continuous slope. Leonardo’s work on canals in northern Italy formed part of a wider program of hydraulic and transport engineering.

Leonardo did not invent the general idea of canals or every form of lock. The important distinction is that his engineering studies helped develop practical lock mechanisms, while the miter-gate principle became a standard feature of navigation locks.