Leonardo da Vinci designed an odometer to measure the distance traveled by a cart.
His design used a wheel that rotated as the cart moved. A linked gear mechanism counted the wheel’s revolutions and transferred the count to a display or container, allowing the operator to estimate the distance covered from the wheel’s known circumference.
The principle is straightforward: distance equals the number of rotations multiplied by the distance traveled in one rotation. Leonardo’s version is often described as an early mechanical odometer and was intended for surveying or road measurement rather than for measuring speed.
Leonardo’s odometer should not be confused with a speedometer. An odometer records accumulated distance, while a speedometer indicates how fast an object is moving at a particular moment. Similar distance-measuring devices existed in antiquity, so Leonardo’s contribution was a Renaissance design and refinement, not the first odometer in history.