Odometer vs. Speedometer

Odometer

An odometer or odograph

is an instrument used for measuring the distance travelled by a vehicle, such as a bicycle or car. The device may be electronic, mechanical, or a combination of the two. The noun derives from the Ancient Greek word ὁδόμετρον, hodómetron, from ὁδός, hodós (“path” or “gateway”) and μέτρον, métron (“measure”). Early forms of the odometer existed in the ancient Greco-Roman world as well as in ancient China. In countries using Imperial units or US customary units it is sometimes called a mileometer or milometer, the former name especially being prevalent in the United Kingdom and among members of the Commonwealth.

Speedometer

A speedometer or a speed meter is a gauge that measures and displays the instantaneous speed of a vehicle. Now universally fitted to motor vehicles, they started to be available as options in the 1900s, and as standard equipment from about 1910 onwards. Speedometers for other vehicles have specific names and use other means of sensing speed. For a boat, this is a pit log. For an aircraft, this is an airspeed indicator.

Charles Babbage is credited with creating an early type of a speedometer, which was usually fitted to locomotives.The electric speedometer was invented by the Croatian Josip Belušić in 1888 and was originally called a velocimeter.