Leonardo da Vinci developed a miter lock for canals using angled double gates.
A miter lock has two gates that meet in a V shape, with the point facing the higher water level. Water pressure pushes the gates together, helping them seal the opening. By opening or closing the gates and changing the water level in the chamber, boats can pass between sections of canal at different elevations.
Leonardo applied this type of canal engineering in connection with Milan’s waterways during the late fifteenth and early sixteenth centuries. His work involved improving navigation and managing water movement, although the underlying idea of miter gates predates him. Leonardo’s contribution was development and practical application rather than sole invention of every canal-lock principle.
A sluice gate controls water flow but does not necessarily form a lock chamber. A pound lock includes the chamber itself; “miter lock” emphasizes the angled meeting gates. That distinction makes the specific answer more precise.