What canal device did Leonardo da Vinci develop using two sloping gates?

Leonardo da Vinci developed a canal lock using mitre gates, known as a mitre lock.

A mitre lock uses two gates that meet at an angle pointing upstream. Water pressure pushes the gates together and helps seal the opening. By filling or emptying the lock chamber, boats can move between waterways at different elevations. Leonardo studied and improved canal-lock mechanisms while working on water engineering in northern Italy.

The design was valuable because canals often had to cross uneven terrain. A lock could raise or lower a boat without requiring a continuous level waterway. Leonardo’s notebooks show detailed attention to gates, channels, pumps, and the movement of water.

A mitre lock is not the same as a single sluice gate. A sluice controls water flow, while a lock chamber changes a vessel’s elevation. Leonardo’s involvement is associated with engineering development and refinement, not necessarily the first invention of every lock principle.