Leonardo da Vinci developed the miter lock, a canal-lock design that helps boats pass between different water levels.
A miter lock uses two paired gates that meet at an angle, typically forming a V that points toward the higher water. Water pressure pushes the gates together and helps seal the opening. Leonardo improved this type of lock while working on canal projects in northern Italy, including the navigation system connected with the Milanese canals.
His contributions included practical details for gates, chambers, and water control. A lock allows a boat to enter a chamber, have the water level raised or lowered, and then leave at the new elevation. This avoids the need to move an entire vessel over a physical step in the canal.
Leonardo did not invent the general idea of canal locks. Earlier water-control systems existed in China and Europe. His importance lies in refining engineering solutions and recording mechanisms that made inland navigation more efficient.