Leonardo da Vinci designed an odometer to record distance traveled by a wheeled device.
An odometer measures distance by counting wheel rotations. Leonardo’s design used a wheel that turned as the vehicle moved and a gear mechanism that transferred those rotations to a counting system. The device could release a small object at regular intervals, making the measured journey visible as a sequence of counted markers.
This idea linked mechanical motion with numerical measurement. It was useful for surveying, mapping, and military planning, where knowing the length of a route mattered even when accurate maps were unavailable.
An odometer is different from a speedometer. An odometer records total distance, while a speedometer shows how fast something is moving at a particular moment. Modern cars combine both instruments, but they perform separate jobs.