Leonardo da Vinci designed an odometer to measure the distance traveled by a cart.
His design used a cart wheel connected to a system of gears. As the wheel turned, the mechanism transferred its motion to a display that counted fixed increments of distance. The device could therefore record how far a cart had traveled without requiring a person to estimate the route.
Leonardo’s odometer appeared in his notebooks as part of his broader interest in surveying, engineering, and military measurement. Accurate distance information was valuable for mapping roads, planning fortifications, and estimating the movement of armies.
Leonardo did not invent the general concept of measuring travel distance; ancient engineers had developed earlier distance-measuring instruments. His contribution was a detailed Renaissance mechanical design that used wheel rotation and gearing in a compact cart-based instrument.