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 hodós (“path”) or
gateway and métron (“measure”). In countries where Imperial units or US
customary units are used, it is sometimes called a mileometer or
milometer, or, colloquially, a tripometer.
History
Odometers were first developed in the
1600s for wagons and other horse-drawn vehicles in order to measure
distances traveled. In 1645 Blaise Pascal invented the pascaline. Though
not an odometer, the pascaline utilized gears to compute measurements.
Each gear contained 10 teeth. The first gear advanced the next gear one
position when moved one complete revolution, the same principle employed
on modern mechanical odometers.
Odometers were developed for ships in
1698 with the odometer invented by the Englishman Thomas Savery.
Benjamin Franklin, U.S. statesman and the first Postmaster General,
built a prototype odometer in 1775 that he attached to his carriage to
help measure the mileage of postal routes. In 1847, William Clayton, a
Mormon pioneer, invented the Roadometer, which he attached to a wagon
used by American settlers heading west. The Roadometer recorded the
distance traveled each day by the wagon trains. The Roadometer used two
gears and was an early example of an odometer with pascaline-style gears
in actual use.
In 1895 Curtis Hussey Veeder invented the
Cyclometer. The Cyclometer was a mechanical device that counted the
number of rotations of a bicycle wheel. A flexible cable transmitted the
number of rotations of the wheel to an analog odometer visible to the
rider, which converted the wheel rotations into the number of miles
traveled according to a predetermined formula.
In 1903 Arthur P. and Charles H. Warner,
two brothers from Beloit, Wisconsin, introduced their patented
Auto-meter. The Auto-Meter used a magnet attached to a rotating shaft to
induce a magnetic pull upon a thin metal disk. Measuring this pull
provided accurate measurements of both distance and speed information to
automobile drivers in a single instrument. The Warners sold their
company in 1912 to the Stewart & Clark Company of Chicago. The new
firm was renamed the Stewart-Warner Corporation. By 1925, Stewart-Warner
odometers and trip meters were standard equipment on the vast majority
of automobiles and motorcycles manufactured in the United States.
Trip meters
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.
GPS used as odometer
Recently, exercise enthusiasts have
observed that an advanced Global Positioning System receiver (GPSr) with
an odometer mode serves as a very accurate pedometer for outdoor
activities. While not truly counting steps (no pendulum is involved) an
advanced GPS odometer can accurately reveal the distance traveled to
within 1/100 of a mile (depending on the model, perhaps 1/1000 of a
mile). 1/1000 of a mile is approximately the distance of a single pace
or 2 steps (1.609 m). Precise metric odometers have a precision of 1/100
or 1/1000 km, 10 or 1 metre(s) respectively.
A GPS with odometer mode is also an
excellent and inexpensive means to verify proper operation of both the
speedometer and odometer mounted in a vehicle.
