Leonardo da Vinci sketched an odometer with a wheel and counting mechanism.
An odometer measures distance traveled. Leonardo’s design used a wheel that turned as it moved over the ground, with a system of gears transferring each rotation to a counter. The counter could record the distance covered, making the device useful for surveying, mapping, and military planning.
The design is often described as an early wheel odometer. Leonardo’s version was connected with his interest in accurate measurement and practical engineering. A known reconstruction uses a wheel whose turns trigger a mechanism that drops small objects into a container, allowing the total distance to be counted indirectly.
Leonardo did not invent the basic idea of measuring travel with a wheel; ancient engineers had developed related devices. His contribution was a detailed Renaissance mechanism showing how gearing and counting could turn movement into recorded distance. An odometer measures distance, while a speedometer measures speed.