Leonardo da Vinci designed an odometer to record how far a wheeled vehicle traveled.
His odometer concept used a wheel that turned as the vehicle moved. A gear mechanism transferred the wheel’s rotation to a counting system, allowing the device to register distance. Leonardo’s version was intended for surveying and engineering work rather than for displaying speed.
The basic principle is straightforward: if the wheel’s circumference is known, each complete rotation represents a fixed distance. Counting rotations therefore gives an estimate of the route traveled. This principle remains central to mechanical odometers, although modern vehicles commonly calculate distance electronically.
Leonardo’s odometer is sometimes confused with his other measuring devices, including designs for anemometers and hygrometers. An odometer measures distance, while an anemometer measures wind and a hygrometer measures humidity. His drawing reflects his broader interest in converting physical motion into useful measurements.