Leonardo da Vinci sketched an odometer using a wheel and a counting mechanism to measure distance.
An odometer records the distance traveled by a vehicle or other moving object. In Leonardo’s design, a wheel would rotate as the machine moved, while linked gears transferred that motion to a series of counting wheels. The mechanism could register completed revolutions and therefore provide an estimate of distance.
Leonardo’s odometer concept formed part of his broader work on military engineering, surveying, and mechanical devices. Accurate distance measurement was useful for mapping roads, planning fortifications, and estimating the movement of machines or troops.
The idea should not be confused with a compass, which indicates direction, or a pedometer, which counts a person’s steps. Leonardo’s design belongs to the long history of wheel-based distance measurement, which later became important in carts, bicycles, cars, and scientific instruments.