Leonardo da Vinci developed a miter-lock design for controlling canal water levels.
The design used two gates that met at an angle pointing upstream. Water pressure helped press the gates together, improving the seal when the lock chamber contained deeper water than the canal section beyond it. This arrangement became a fundamental feature of canal locks.
Leonardo worked on canal engineering in Milan and studied ways to improve navigation around changes in elevation. A lock allows boats to move between water levels without draining or flooding an entire canal section at once.
Leonardo was not the first person to use every principle of canal navigation, and the history of miter gates predates or overlaps his work. His drawings are significant because they document a refined engineering approach associated with Renaissance water-management projects.