Leonardo da Vinci designed an odometer for measuring distance during surveying. His concept used a wheeled cart whose rotation triggered a mechanism that released a fixed number of small objects into a container.
By counting the objects collected, an operator could estimate how far the cart had traveled. The design connected movement of a wheel to a countable record, making it an early mechanical approach to distance measurement.
Leonardo’s odometer was intended for practical measurement rather than personal transportation. Surveyors and engineers could use such information when mapping land, planning roads, or laying out construction projects.
An odometer differs from a tachometer: an odometer records distance, while a tachometer records rotational speed. Leonardo’s design also belongs to a much older history of distance counters; ancient engineers had already developed related devices, including the hodometer associated with measuring road distances.