Leonardo da Vinci improved the miter lock, a canal device that retains water at different levels using hinged gates.
A lock allows boats to move between sections of water with different elevations. The chamber is closed, its water level is adjusted, and the vessel then exits through the opposite gate. Miter gates meet at an angle pointing upstream; water pressure helps press them together and seal the opening.
Leonardo studied canal engineering extensively in northern Italy and is associated with improvements to lock design, including practical arrangements for gates and water control. His work supported navigation and irrigation projects around Milan.
Leonardo did not invent the basic principle of every canal lock, and earlier water-control structures existed. His contribution belongs to a long engineering history in which Renaissance designers refined gates, chambers, and operating procedures for reliable navigation.