Leonardo da Vinci designed an odometer to measure distance by recording the rotations of a wheel.
His cart-like design used a wheel that moved along the ground and a counting mechanism connected to its rotation. As the wheel turned, a series of gears could transfer motion to a display or container, allowing the machine to register traveled distance. The principle is the same basic idea used by mechanical odometers in later vehicles.
Leonardo’s version was intended for surveying and engineering work rather than automobile travel. Accurate distance measurement was valuable for mapping, construction, road planning, and military logistics. The result depended on knowing the wheel’s circumference and maintaining contact with the ground.
An odometer measures distance, not speed. That distinction separates it from a speedometer, which measures how fast an object is moving at a particular moment. Leonardo’s design is also related to his broader studies of gears, motion, and mechanical measurement.