Leonardo da Vinci designed an odometer to measure distance traveled by a cart.
An odometer records the distance covered by a vehicle or wheeled machine. Leonardo’s design used the rotation of a wheel to drive a sequence of gears. After a set number of wheel rotations, a mechanism released a small object, allowing the operator to count the measured increments.
This approach translated circular motion into a running distance count. It was useful for surveying, mapping, and military engineering, where knowing the length of a road or the position of a work site mattered. The instrument did not need electricity; its measurement came from wheel circumference and gear ratios.
Leonardo’s device is sometimes compared with a modern speedometer, but the two instruments measure different things. An odometer measures accumulated distance, whereas a speedometer measures current speed. A pedometer counts a person’s steps rather than a cart’s wheel rotations.