Engineering Excellence - Odometer

This odometer is used to measure the distance travelled. Leonardo's odometer resembles a wheelbarrow with sprocket wheels attached. Each time the cartwheel completes one full rotation, it moves the small vertical wheel one notch forward.
The horizontal wheel is then moved one notch and releases a pebble or wooden ball from a small hole into a box. The distance travelled can be calculated by counting the number of pebbles or balls that have been collected and multiplying by the circumference of the wheel. This design is a variation of an instrument designed by the Roman architect and engineer Vitruvius.