Sluice gate

Leonardo tries to improve the systems of locks and channels already in use in Milan. This is a mechanism for opening and closing sluice doors: a small wicket with a latch could be operated from above. Once opened, it allowed enough water to pour in so as to balance the pressure on the two sides of the main door. The opening was thus easier. This drawing was produced during his stay in Milan under the French domination and it depicts the lock of S. Marco's naviglio. On the same sheet Leonardo sketches the lock plan and adds various comments.
Codex Atlanticus, sheet 656 1506-1513