Leonardo da Vinci sketched an odometer for measuring the distance traveled by a cart.
His design used a cart wheel connected to a counting mechanism. As the wheel turned, the mechanism advanced and recorded the distance covered. The concept is an early example of converting repeated mechanical motion into a numerical measurement.
Leonardo’s odometer was related to surveying and mapmaking. Accurate distance measurements were valuable for military planning, road surveys, and the design of canals and fortifications. The machine could be calibrated by determining the circumference of its wheel and counting how many rotations occurred.
An odometer measures distance, not speed. A speedometer measures how fast an object is moving, while a compass gives direction. Leonardo’s design also predates modern vehicle odometers, which use electronic sensors or geared systems connected to a vehicle’s wheels. His sketch belongs to his wider study of practical measuring instruments.