Which Leonardo da Vinci device used wheel rotations to estimate the distance traveled?

Leonardo da Vinci’s odometer used wheel rotations to estimate the distance traveled. His design, recorded in the Codex Atlanticus, was a cart-like measuring device that counted the turns of a wheel as it moved along a road.

The mechanism used a wheel and a gear system connected to a container that released a small object after a set number of rotations. By counting the released objects, an operator could estimate how far the cart had traveled. The design was useful for surveying, mapping and measuring roads, even though it was not an electronic instrument and did not directly display a number.

An odometer is not the same as a pedometer, which counts a person’s steps, or a speedometer, which measures speed. Leonardo’s version belongs to a much older history of distance measurement: ancient Greek and Roman engineers also developed wheel-based devices for surveying roads. Leonardo’s contribution was a detailed Renaissance mechanical design rather than the invention of the basic idea of measuring distance with wheels.