Leonardo da Vinci used an odometer concept to record distance traveled by counting wheel rotations.
His design linked a wheel to a system of gears that advanced a counting display as the wheel turned. Because the wheel's circumference was known, each complete revolution represented a fixed distance. The mechanism could therefore measure the length of a road or the progress of a surveying expedition without requiring a modern electronic sensor.
Leonardo's odometer was related to practical mapmaking and engineering. Surveyors could use such a device to estimate distances while traveling, especially where direct measurement with a chain was inconvenient. It was a mechanical instrument, not a device for measuring speed.
An odometer is sometimes confused with a speedometer. An odometer measures accumulated distance, while a speedometer measures current speed. Leonardo explored many instruments for observation and measurement, and his wheel-based distance recorder belongs to that broader tradition of Renaissance engineering.