Leonardo da Vinci designed an odometer that measured distance with a wheel and falling stones.
His road-measuring device used a cart whose wheel turned a gear mechanism. At regular intervals, the mechanism released a stone into a container. Counting the stones revealed how many wheel rotations had occurred and therefore how far the cart had traveled, provided the wheel’s circumference was known.
This is an early mechanical odometer concept. An odometer records distance traveled, while a speedometer measures speed. A pedometer counts a person’s steps, so it is not the same instrument even though both involve counting movement.
Leonardo’s design reflects his interest in surveying, military engineering, and the controlled transmission of motion. It was not an electronic instrument and did not display a numerical reading automatically. Instead, it converted wheel rotation into a count that an observer could interpret after or during a journey.