An odometer or odograph is an instrument used for measuring the

distance Distance is a numerical or occasionally qualitative measurement of how far apart objects or points are. In physics or everyday usage, distance may refer to a physical length or an estimation based on other criteria (e.g. "two counties over"). ...

traveled by a vehicle, such as a bicycle or car. The device may be electronic, mechanical, or a combination of the two ( electromechanical). The noun derives from

ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic pe ...

, ''hodómetron'', from , ''hodós'' ("path" or "gateway") and , ''métron'' ("measure"). Early forms of the odometer existed in the ancient Greco-Roman world as well as in

ancient China The earliest known written records of the history of China date from as early as 1250 BC, from the Shang dynasty (c. 1600–1046 BC), during the reign of king Wu Ding. Ancient historical texts such as the '' Book of Documents'' (early chapt ...

. 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 The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and ...

and among members of the

Commonwealth A commonwealth is a traditional English term for a political community founded for the common good. Historically, it has been synonymous with "republic". The noun "commonwealth", meaning "public welfare, general good or advantage", dates from the ...

History

Classical Era

Possibly the first evidence for the use of an odometer can be found in the works of the ancient Roman Pliny (NH 6. 61-62) and the ancient Greek

Strabo Strabo''Strabo'' (meaning "squinty", as in strabismus) was a term employed by the Romans for anyone whose eyes were distorted or deformed. The father of Pompey was called " Pompeius Strabo". A native of Sicily so clear-sighted that he could s ...

(11.8.9). Both authors list the distances of routes traveled by

Alexander the Great Alexander III of Macedon ( grc, Ἀλέξανδρος, Alexandros; 20/21 July 356 BC – 10/11 June 323 BC), commonly known as Alexander the Great, was a king of the ancient Greek kingdom of Macedon. He succeeded his father Philip II to ...

(r. 336-323 BC) as by his bematists Diognetus and Baeton. However, the high accuracy of the bematists's measurements rather indicates the use of a mechanical device. For example, the section between the cities Hecatompylos and Alexandria Areion, which later became a part of the

silk road The Silk Road () was a network of Eurasian trade routes active from the second century BCE until the mid-15th century. Spanning over 6,400 kilometers (4,000 miles), it played a central role in facilitating economic, cultural, political, and rel ...

, was given by Alexander's bematists as 575 Roman miles (529 English miles) long, that is with a deviation of 0.2% from the actual distance (531 English miles). From the nine surviving bematists' measurements in Pliny's '' Naturalis Historia'' eight show a deviation of less than 5% from the actual distance, three of them being within 1%. Since these minor discrepancies can be adequately explained by slight changes in the tracks of roads during the last 2300 years, the overall accuracy of the measurements implies that the bematists already must have used a sophisticated device for measuring distances, although there is no direct mention of such a device. An odometer for measuring distance was first described by

Vitruvius Vitruvius (; c. 80–70 BC – after c. 15 BC) was a Roman architect and engineer during the 1st century BC, known for his multi-volume work entitled '' De architectura''. He originated the idea that all buildings should have three attribut ...

around 27 and 23 BC, during the

First Punic War The First Punic War (264–241 BC) was the first of Punic Wars, three wars fought between Roman Republic, Rome and Ancient Carthage, Carthage, the two main powers of the western Mediterranean in the early 3rd century BC. For 23 years ...

, although the actual inventor may have been

Archimedes of Syracuse Archimedes of Syracuse (;; ) was a Greek mathematician, physicist, engineer, astronomer, and inventor from the ancient city of Syracuse in Sicily. Although few details of his life are known, he is regarded as one of the leading scientists ...

(c. 287 BC – c. 212 BC).

Hero of Alexandria Hero of Alexandria (; grc-gre, Ἥρων ὁ Ἀλεξανδρεύς, ''Heron ho Alexandreus'', also known as Heron of Alexandria ; 60 AD) was a Greek mathematician and engineer who was active in his native city of Alexandria, Roman Egypt. H ...

(10 AD – 70 AD) describes a similar device in chapter 34 of his ''

Dioptra A dioptra (sometimes also named dioptre or diopter, from el, διόπτρα) is a classical astronomical and surveying instrument, dating from the 3rd century BC. The dioptra was a sighting tube or, alternatively, a rod with a sight at b ...

''. The machine was also used in the time of Roman Emperor

Commodus Commodus (; 31 August 161 – 31 December 192) was a Roman emperor who ruled from 177 to 192. He served jointly with his father Marcus Aurelius from 176 until the latter's death in 180, and thereafter he reigned alone until his assassination. ...

(c. 192 AD), although after this point in time there seems to be a gap between its use in Roman times and that of the 15th century in Western Europe. Some researchers have speculated that the device might have included technology similar to that of the Greek

Antikythera mechanism The Antikythera mechanism ( ) is an Ancient Greek hand-powered orrery, described as the oldest example of an analogue computer used to predict astronomical positions and eclipses decades in advance. It could also be used to track the four-y ...

. The odometer of Vitruvius was based on chariot wheels of 4 Roman feet (1.18 m) diameter turning 400 times in one Roman mile (about 1,480 m). For each revolution a pin on the axle engaged a 400-tooth cogwheel thus turning it one complete revolution per mile. This engaged another gear with holes along the circumference, where pebbles (''

calculus Calculus, originally called infinitesimal calculus or "the calculus of infinitesimals", is the mathematics, mathematical study of continuous change, in the same way that geometry is the study of shape, and algebra is the study of generalizati ...

'') were located, that were to drop one by one into a box. The distance traveled would thus be given simply by counting the number of pebbles. Whether this instrument was ever built at the time is disputed.

Leonardo da Vinci Leonardo di ser Piero da Vinci (15 April 14522 May 1519) was an Italian polymath of the High Renaissance who was active as a painter, draughtsman, engineer, scientist, theorist, sculptor, and architect. While his fame initially rested on ...

later tried to build it himself according to the description, but failed. However, in 1981 engineer Andre Sleeswyk built his own replica, replacing the square-toothed gear designs of Leonardo with the triangular, pointed teeth found in the ''Antikythera mechanism''. With this modification, the Vitruvius odometer functioned perfectly.

Imperial China

Han Dynasty and Three Kingdoms period

The odometer was also independently invented in

, possibly by the prolific inventor and early scientist Zhang Heng (78 AD – 139 AD) of the

Han Dynasty The Han dynasty (, ; ) was an Dynasties in Chinese history, imperial dynasty of China (202 BC – 9 AD, 25–220 AD), established by Emperor Gaozu of Han, Liu Bang (Emperor Gao) and ruled by the House of Liu. The dynasty was preceded by th ...

. By the 3rd century (during the

Three Kingdoms The Three Kingdoms () from 220 to 280 AD was the tripartite division of China among the dynastic states of Cao Wei, Shu Han, and Eastern Wu. The Three Kingdoms period was preceded by the Eastern Han dynasty and was followed by the West ...

Period), the Chinese had termed the device as the 'jì lĭ gŭ chē' (記里鼓車), or ' li-recording drum carriage' (Note: the modern measurement of li = ). Chinese texts of the 3rd century tell of the mechanical carriage's functions, and as one li is traversed, a mechanical-driven wooden figure strikes a drum, and when ten li is traversed, another wooden figure would strike a gong or a bell with its mechanical-operated arm. Despite its association with Zhang Heng or even the later Ma Jun (c. 200–265), there is evidence to suggest that the invention of the odometer was a gradual process in Han Dynasty China that centered around the ''huang men'' court people (i.e. eunuchs, palace officials, attendants and familiars, actors, acrobats, etc.) that would follow the musical procession of the royal 'drum-chariot'. The historian

Joseph Needham Noel Joseph Terence Montgomery Needham (; 9 December 1900 – 24 March 1995) was a British biochemist, historian of science and sinologist known for his scientific research and writing on the history of Chinese science and technology, i ...

asserts that it is no surprise this social group would have been responsible for such a device, since there is already other evidence of their craftsmanship with mechanical toys to delight the emperor and the court. There is speculation that some time in the 1st century BC (during the Western Han Dynasty), the beating of drums and gongs were mechanically-driven by working automatically off the rotation of the road-wheels. This might have actually been the design of one Loxia Hong (c. 110 BC), yet by 125 AD the mechanical odometer carriage in China was already known (depicted in a mural of the Xiaotangshan Tomb). The odometer was used also in subsequent periods of Chinese history. In the historical text of the '' Jin Shu'' (635 AD), the oldest part of the compiled text, the book known as the ''Cui Bao'' (c. 300 AD), recorded the use of the odometer, providing description (attributing it to the Western Han era, from 202 BC–9 AD). The passage in the ''Jin Shu'' expanded upon this, explaining that it took a similar form to the mechanical device of the south-pointing chariot invented by Ma Jun (200–265, see also differential gear). As recorded in the '' Song Shi'' of the

Song Dynasty The Song dynasty (; ; 960–1279) was an imperial dynasty of China that began in 960 and lasted until 1279. The dynasty was founded by Emperor Taizu of Song following his usurpation of the throne of the Later Zhou. The Song conquered the res ...

(960-1279 AD), the odometer and south-pointing chariot were combined into one wheeled device by engineers of the 9th century, 11th century, and 12th century. The '' Sunzi Suanjing'' (Master Sun's Mathematical Manual), dated from the 3rd century to 5th century, presented a mathematical problem for students involving the odometer. It involved a given distance between two cities, the small distance needed for one rotation of the carriage's wheel, and the posed question of how many rotations the wheels would have in all if the carriage was to travel between point A and B.

Song Dynasty

The historical text of the '' Song Shi'' (1345 AD), recording the people and events of the Chinese

(960–1279), 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.
he mile-measuring carriage He or HE may refer to: Language * He (pronoun), an English pronoun * He (kana), the romanization of the Japanese kana へ * He (letter), the fifth letter of many Semitic alphabets * He (Cyrillic), a letter of the Cyrillic script called ''He'' ...
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:

What follows is a long dissertation made by the Chief Chamberlain Lu Daolong on the ranging measurements and sizes of wheels and gears, along with a concluding description at the end of how the device ultimately functions:

The vehicle should have a single pole and two wheels. On the body are two storeys, each containing a carved wooden figure holding a drumstick. The road-wheels are each 6 ft in diameter, and 18 ft in circumference, one evolution covering 3 paces. According to ancient standards the pace was equal to 6 ft and 300 paces to a li; but now the li is reckoned as 360 paces of 5 ft each.

ote: the measurement of the Chinese-mile unit, the li, was changed over time, as the li in Song times differed from the length of a li in Han times.

The vehicle wheel (li lun) is attached to the left road-wheel; it has a diameter of 1.38 ft with a circumference of 4.14 ft, and has 18 cogs (chhih) 2.3 inches apart. There is also a lower horizontal wheel (hsia phing lun), of diameter 4.14 ft and circumference 12.42 ft, with 54 cogs, the same distance apart as those on the vertical wheel (2.3 inches). (This engages with the former.)

Upon a vertical shaft turning with this wheel, there is fixed a bronze "turning-like-the-wind wheel" (hsuan feng lun) which has (only) 3 cogs, the distance between these being 1.2 inches. (This turns the following one.) In the middle is a horizontal wheel, 4 ft in diameter, and 12 ft circumference, with 100 cogs, the distance between these cogs being the same as on the "turning-like-the-wind wheel" (1.2 inches).

Next, there is fixed (on the same shaft) a small horizontal wheel (hsiao phing lun) 3.3 inches in diameter and 1 ft in circumference, having 10 cogs 1.5 inches apart. (Engaging with this) there is an upper horizontal wheel (shang phing lun) having a diameter of 3.3 ft and a circumference of 10 ft, with 100 cogs, the same distance apart as those of the small horizontal wheel (1.5 inches).

When the middle horizontal wheel has made 1 revolution, the carriage will have gone 1 li and the wooden figure in the lower story will strike the drum. When the upper horizontal wheel has made 1 revolution, the carriage will have gone 10 li and the figure in the upper storey will strike the bell. The number of wheels used, great and small, is 8 inches in all, with a total of 285 teeth. Thus the motion is transmitted as if by the links of a chain, the "dog-teeth" mutually engaging with each other, so that by due revolution everything comes back to its original starting point (ti hsiang kou so, chhuan ya hsiang chih, chou erh fu shih).

Subsequent developments

Odometers were first developed in the 1600s for wagons and other horse-drawn vehicles in order to measure distances traveled.

Levinus Hulsius Levinus Hulsius (1550 – 1606) was a maker and dealer of fine scientific instruments; publisher and printer; linguist and lexicographer; wrote extensively on the construction of geometrical instruments. Although he was born in Flanders he lived ...

published the odometer in 1604 in his work ''Gründtliche Beschreibung deß Diensthafften und Nutzbahrn Instruments Viatorii oder Wegzählers, So zu Fuß, zu Pferdt unnd zu Fußen gebraucht werden kann, damit mit geringer mühe zu wissen, wie weit man gegangen, geritten, oder gefahren sey: als auch zu erfahren, ohne messen oder zehlen, wie weit von einem Orth zum andern. Daneben wird auch der grosse verborgene Wegweiser angezeiget und vermeldet''. In 1645, the French mathematician 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 Thomas Savery (; c. 1650 – 15 May 1715) was an English inventor and engineer. He invented the first commercially used steam-powered device, a steam pump which is often referred to as the "Savery engine". Savery's steam pump was a revolutionar ...

Benjamin Franklin Benjamin Franklin ( April 17, 1790) was an American polymath who was active as a writer, scientist, inventor, statesman, diplomat, printer, publisher, and political philosopher. Encyclopædia Britannica, Wood, 2021 Among the leading int ...

, 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 and

Orson Pratt Orson Pratt Sr. (September 19, 1811 – October 3, 1881) was an American mathematician and religious leader who was an original member of the Quorum of the Twelve Apostles of the Church of Christ (Latter Day Saints). He became a member of the ...

, pioneers of

the Church of Jesus Christ of Latter-day Saints The Church of Jesus Christ of Latter-day Saints, informally known as the LDS Church or Mormon Church, is a Nontrinitarianism, nontrinitarian Christianity, Christian church that considers itself to be the Restorationism, restoration of the ...

, first implemented the ''Roadometer'' they had invented earlier (a version of the modern odometer), which they attached to a wagon used by American settlers heading west. It recorded the distance traveled each day by the

wagon trains ''Wagon Train'' is an American Western series that aired 8 seasons: first on the NBC television network (1957–1962), and then on ABC (1962–1965). ''Wagon Train'' debuted on September 18, 1957, and became number one in the Nielsen ratings. ...

. 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. By the early 2000s, mechanical odometers would be phased out on cars from major manufacturers. The

Pontiac Grand Prix The Grand Prix is a line of automobiles produced by the Pontiac Division of General Motors from 1962 until 2002 for coupes and 1989–2008 for sedans. First introduced as a full-size performance coupe for the 1962 model year, the model varie ...

was the last GM car sold in the US to offer a mechanical odometer in 2003, the Canadian-built Ford Crown Victoria and Mercury Grand Marquis were the last Fords sold with one in 2005.

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. Many modern vehicles often have multiple trip meters. Most mechanical 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.

Clocking/busting miles and legality

A form of

fraud In law, fraud is intentional deception to secure unfair or unlawful gain, or to deprive a victim of a legal right. Fraud can violate civil law (e.g., a fraud victim may sue the fraud perpetrator to avoid the fraud or recover monetary compen ...

is to tamper with the reading on an odometer and presenting the incorrect number of miles/kilometres traveled to a prospective buyer; this is often referred to as "clocking" in the UK and "busting miles" in the US. This is done to make a car appear to have been driven less than it really has been, and thus increase its apparent market value. Most new cars sold today use

digital Digital usually refers to something using discrete digits, often binary digits. Technology and computing Hardware *Digital electronics, electronic circuits which operate using digital signals ** Digital camera, which captures and stores digital ...

odometers that store the mileage in the vehicle's

engine control unit An engine control unit (ECU), also commonly called an engine control module (ECM), is a type of electronic control unit that controls a series of actuators on an internal combustion engine to ensure optimal engine performance. It does this by ...

, making it difficult (but not impossible) to manipulate the mileage electronically. With mechanical odometers, the

speedometer A speedometer or 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 early 20th century, and as standard equipment f ...

can be removed from the car dashboard and the digits wound back, or the drive cable can be disconnected and connected to another odometer/speedometer pair while on the road. Older vehicles can be driven in reverse to subtract mileage, a concept which provides the premise for a classic scene in the comedy film '' Ferris Bueller's Day Off'', but modern odometers add mileage driven in reverse to the total as if driven forward, thereby accurately reflecting the true total wear and tear on the vehicle. The resale value of a vehicle is often strongly influenced by the total distance shown on the odometer, yet odometers are inherently insecure because they are under the control of their owners. Many jurisdictions have chosen to enact laws which penalize people who are found to commit odometer fraud. In the US (and many other countries), vehicle mechanics are also required to keep records of the odometer any time a vehicle is serviced or inspected. Companies such as Carfax then use these data to help potential car buyers detect whether odometer rollback has occurred.

Prevalence

Research by Irish vehicle check specialist

Cartell Cartell is an Irish vehicle checking company which commenced trading in 2006. It operates an online service to allow prospective vehicle purchasers to verify the history of a vehicle before purchasing. The checks available include details of fi ...

found that 20% of vehicles imported to Ireland from

Great Britain Great Britain is an island in the North Atlantic Ocean off the northwest coast of continental Europe. With an area of , it is the largest of the British Isles, the largest European island and the ninth-largest island in the world. It ...

and

Northern Ireland Northern Ireland ( ga, Tuaisceart Éireann ; sco, label=Ulster Scots dialect, Ulster-Scots, Norlin Airlann) is a part of the United Kingdom, situated in the north-east of the island of Ireland, that is #Descriptions, variously described as ...

had had their mileometers altered to show a lower mileage.

Accuracy

Most odometers work by counting wheel rotations and assume that the distance traveled is the number of wheel rotations times the tire circumference, which is a standard tire diameter times pi (3.1416). If nonstandard or severely worn or underinflated tires are used then this will cause some error in the odometer. The formula is (actual distance traveled) = ( (final odometer reading) – (initial odometer reading) ) * (actual tire diameter) / (standard tire diameter). It is common for odometers to be off by several percent. Odometer errors are typically proportional to speedometer errors.

References

Sources

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External links

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