An odometer is a device that measures distance traveled by a vehicle. It can be electronic, mechanical, or a combination. The word comes from Greek words meaning "path" and "measure". In some countries it is also called a milometer.
The ancient Chinese used odometers on carriages as early as the Song Dynasty from 960-1279 AD. Descriptions from that time period provide details on the construction and appearance of these early odometers.
Modern cars include a trip meter in addition to the main odometer. Unlike the odometer, the trip meter can be reset and used to track portions of longer journeys or fuel efficiency over individual tankfuls of gas.
2. An odometer or odograph is an instrument
that indicates distance traveled by a vehicle,
such as a bicycle or automobile. The device
may be electronic, mechanical, or a
combination of the two. The word derives
from the Greek words hod坦s ("path" or
"gateway") and m辿tron ("measure"). In
countries where Imperial units or US
customary units are used, it is sometimes
called amileometer or milometer, or,
colloquially, a tripometer.
5. The historical text of the Song Shi (1345 AD), recording the
people and events of the Chinese Song Dynasty (9601279), also
mentioned the odometer used in that period. However, unlike
written sources of earlier periods, it provided a much more
thoroughly detailed description of the device that harkens back
to its ancient form (Wade-Giles spelling):
The odometer. [The mile-measuring carriage] is painted red,
with pictures of flowers and birds on the four sides, and
constructed in two storeys, handsomely adorned with carvings.
At the completion of every li, the wooden figure of a man in the
lower storey strikes a drum; at the completion of every ten li, the
wooden figure in the upper storey strikes a bell. The carriage-
pole ends in a phoenix-head, and the carriage is drawn by four
horses. The escort was formerly of 18 men, but in the 4th year of
the Yung-Hsi reign-period (987 AD) the emperor Thai Tsung
increased it to 30. In the 5th year of the Thien-Sheng reign-
period (1027 AD) the Chief Chamberlain Lu Tao-lung presented
specifications for the construction of odometers as follows
6. Most modern cars include a trip meter (trip
odometer). Unlike the odometer, a trip meter is reset
at any point in a journey, making it possible to record
the distance traveled in any particular journey or part
of a journey. It was traditionally a purely mechanical
device but, in most modern vehicles, it is now
electronic. Luxury vehicles often have multiple trip
meters. Most trip meters will show a maximum value
of 999.9. The trip meter may be used to record the
distance traveled on each tank of fuel, making it very
easy to accurately track the energy efficiency of the
vehicle; another common use is resetting it to zero at
each instruction in a sequence of driving directions,
to be sure when one has arrived at the next turn.