Leonardo da Vinci designed an odometer to count the distance traveled by a cart.
His cart-mounted device used the rotation of a wheel to trigger a counting mechanism. As the cart moved, a sequence of gears or compartments could record the revolutions and translate them into an estimate of distance.
Leonardo’s design belongs to his broader studies of measurement, gears, and automated mechanisms. It was especially useful as a surveying concept because a wheeled device could measure a route without requiring a person to repeatedly pace or mark the ground.
An odometer measures distance, while an altimeter measures height and a barometer measures atmospheric pressure. The term is often associated with modern vehicle dashboards, but the underlying idea of counting wheel rotations is much older.