Leonardo da Vinci designed an odometer to record the distance traveled by a vehicle.
His odometer concept was attached to a cart wheel. As the wheel turned, a mechanism counted rotations and transferred the count through gears. The device released a small object, such as a stone, at set intervals so the accumulated distance could be measured.
This approach converted wheel rotation into a practical distance measurement. Because a wheel travels a fixed circumference in one complete turn, counting turns provides an estimate of how far the cart has moved. The accuracy depends on the wheel’s size and on avoiding slipping or uneven ground.
Leonardo’s odometer belonged to a larger group of surveying and military-engineering instruments. It was not an electronic dashboard device like those found in modern cars. The word “odometer” comes from Greek roots meaning path or road and measure, and the same basic measurement principle remains useful today.