Leonardo da Vinci designed a miter lock, a canal device whose two angled gates press together under water pressure.
A miter lock has gates that meet in a V shape pointing upstream. Water pressure pushes the gates toward one another and helps seal the opening. When the water levels on both sides are equalized, the gates can be opened and a boat can pass through. Leonardo used and refined this principle in canal engineering in Milan.
The system allowed boats to move between sections of canal with different water levels. It was especially useful where a canal had to cross uneven ground or connect with another waterway. Leonardo’s work on locks formed part of his broader engineering activity involving canals, mills, bridges, and water control.
A miter lock is different from a simple sluice gate, which regulates flow but does not necessarily create a navigable chamber. Leonardo did not invent the general idea of locks, but his designs helped develop practical canal mechanisms.