Odometer

An odometer is an instrument that measures the distance traveled by a vehicle, deriving its name from the Greek words for path and measure. The device was described independently in the ancient Greco-Roman world, first by the Roman engineer Vitruvius in the 1st century BC and later by Hero of Alexandria, and separately in Han dynasty China, where it is credited to the polymath Zhang Heng in the 2nd century AD; the Chinese version mechanically struck a drum or gong at set distances. Mechanical odometers for wagons and carriages were revived and refined in Europe from the 1600s onward.