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A 'mile' is a unit of length, usually used to measure distance, in a number of different systems, including Imperial units, United States customary units and Norwegian/Swedish mil. Its size can vary from system to system, but in each is between 1 and 10 kilometers. In contemporary English contexts ''mile'' refers to either:

★ the 'statute mile' of 5,280 feet (1,609.344 m exactly), or 63360 inches

★ the international 'nautical mile' of exactly 1,852 m (about 6,076 feet).
There have been several abbreviations for mile, with and without trailing period: mi, ml, m, M. NIST now uses and recommends "mi", but miles per hour are usually shortened to "mph", "m.p.h." or "MPH" instead of "mi/h".

Contents

The original mile

Types of mile

Statute miles

Nautical miles

Other miles

See also

References

External links

The original mile

A unit of distance called a ''mile'' was first used by the Romans and denoted a distance of 1000 paces (1 pace is 2 steps, 1000 paces being, in Latin, ''mille passus'') or 5000 Roman feet, and corresponded to about 1480 meters, or 1618 modern yards.^[1]
The current definition of a mile as 5,280 feet (as opposed to 5000) dates to the 13th century, and was confirmed by statute in the reign of Queen Elizabeth I; the change was needed to accommodate the rod which (as opposed to the mile) was a measure ensconced in legal documents (see the discussion about furlongs).

Types of mile

In modern usage, various distances are referred to as ''miles''.

Statute miles

The Statute Mile is the distance typically meant when the word ''mile'' is used without other qualifying words (e.g. Nautical Mile, see below).
It originates from a Statute of the English parliament in 1592 during the reign of Elizabeth I. This defined the Statute Mile as 5,280 feet or 1,760 yards; or 63,360 inches. The reason for these rather irregular numbers is that 5280 feet is made up of eight furlongs (the length generally that a furrow was plowed before the horses were turned, furlong = furrow-long). In turn a furlong is 10 chains (a surveyor's chain, used as such until laser rangefinders took over); a chain is 22 yards and a yard is three feet, making up 5280 ft. 22 yards is also the length of a cricket pitch, a game originating in England and played today particularly in countries that were once part of the British Empire.
Before the statute of the English parliament, there was confusion on the length of the "mile". The Irish mile was 2240 yards (6720 ft) and the Scottish mile was the length of the so-called 'Royal Mile' in Edinburgh, from the Castle to the Palace of Holyroodhouse, and was 1976 yards (5928 ft). In England the Roman mile of 5,000 feet was often used, a length not divisible without fractions into furlongs or yards (5000 ft = 1666 2/3 yards). For other "miles" see the list below. In the late 1500s, accurate ground mapping was becoming commonly available, such as Saxton's maps of the English Counties. Therefore, a standard mile became more important than before, hence the Parliamentary Statute. It may also have been related to the potential for taxation, for which a standard measure across the country would be required to prevent regional arguments about length and area.

★ In modern times, the 'international statute mile' is by international agreement. It is defined to be precisely 1,760 international yards (by definition, 0.9144 m each) and is therefore exactly 1,609.344 metres ('1.609344 km'). A kilometer is 0.621371192 miles. It is used in the United States and the United Kingdom as part of the U.S. customary and Imperial systems of units, respectively. The components of the International Statute Mile are the same as those of the English Parliamentary Statute of 1592, that is 8 furlongs, 80 chains or 5,280 international feet.

★ All of the metric conversions follow from the international agreement, made in 1960, that one inch equals 25.4 millimetres (2.54 centimetres) exactly. There are 12 inches to a foot and all of the feet-to-metre conversions (and vice versa) follow.

★ The 'U.S. survey mile' is based on an inch defined by 1 metre = 39.37 inches exactly. It is equal to 5,280 U.S. survey feet, 6,336/3,937 km or approximately 1,609.347 metres. One ''international mile'' is equal to 0.999 998 survey miles. The survey mile is used by the United States Public Land Survey System.

Nautical miles

Main articles: Nautical mile

The 'nautical mile' was originally defined as 1 minute of arc along a meridian (or in some instances any great circle) of the Earth. Although this distance varies depending on the latitude of the meridian (or great circle) where it is used, on average it is about 6,076 feet (about 1852 m or 1.15 statute miles).
The nautical mile per hour is known as the 'knot'.
Navigators use dividers to step off the distance between two points on the map, then place the open dividers against the minutes-of-latitude scale at the edge of the map, and read off the distance in Nautical Miles. Since it is now known that the earth is an ellipsoid (spheroid), not a sphere, the distance of Nautical Miles derived from this method varies from the equator to the poles. For instance, using the WGS84 Ellipsoid, the commonly accepted Earth model for many purposes today, 1 minute of latitude at the WGS84 equator is 6,087 feet and at the poles is 6,067 feet
In the United States, the nautical mile was defined in the nineteenth century as 6,080.2 feet (1,853.249 m), whereas in Britain the 'Admiralty Nautical Mile' was defined as 6,080 feet (1,853.184 m) and was approximately one minute of latitude in the latitudes of the south of the UK. Other nations had different definitions of the nautical mile, but it is now internationally defined to be exactly 1,852 metres.

★ The nautical mile is almost universally used for navigation in aviation, maritime, and nautical roles because of its relationship with degrees and minutes of latitude and the ability to use the latitude scale of a map for distance measuring.

★ An alternative term - 'sea mile' - is still used for the distance of one minute of latitude.

Other miles

★ The 'Roman mile' (Latin ''mille passus'', plural ''milia passuum''), equalled 1000 double paces (''passus'', plural ''passūs'') of five Roman feet (''pēs'', plural ''pedēs'') each. Its length was 5,000 Roman feet, approximately 1500 m.

★ The 'Danish mile' (Danish 'mil') was equal to 7,532 metres (or 24,000 Danish feet or 12,000 alen).

★ The 'Data mile' is used in radar-related subjects and is equal to 6,000 feet (1.8288 kilometres).

★ The 'Dutch mile' (the "Hollandic" mile) was nearly the 19th part of a degree (~5.8 kilometres).

★ The 'Dutch mile' (or "Netherlandic" mile) was exactly 1 kilometre in the Dutch Metric System 1820-1870.

★ The 'German mile' was reckoned to be the 15th part of a degree (and thus about four nautical miles in length or 6.4 kilometres).

★ The 'Irish mile' was equal to 2,240 yards (2,048.256 m).

★ The 'Italian mile' also called the 'Roman mile' (~1.52 kilometres or 0.944 statute miles) was a thousand paces of 5 Roman feet each (the Roman foot being one fifth of an inch less than the London foot).

★ The term 'metric mile' is used in sports such as athletics (track and field) and speedskating to denote a distance of 1.5 kilometres. In United States high school competition the term is sometimes used for a race of 1.6 kilometres.

★ The 'Norwegian/Swedish mil' (the Swedish mile, currently used in Norway and Sweden) has been defined as 10 kilometres from 1 January 1889, when a metric system was introduced in Sweden. The pre-metric ''mil'' (in earlier times ''rast'', lit. ''rest, pause'') was about 11.3 kilometres in Norway (see ''Long Mile'' below) and 10,688.54 metres in Sweden, representing a suitable distance between rests when walking. In informal and non-precise situations involving longer distances of several kilometres, the mil is, as a rule, used instead of the kilometre. It is also used commonly for measuring vehicle fuel consumption; litres per mil means litres consumed per 10 kilometres [1].

★ The 'Polish mile' was nearly equal to the Dutch mile.

★ The 'Scottish mile' was equal to 1,976.5 yards (1,807.3116 m).

★ The 'long mile', traditionally used by the Norwegians, Swedes and Hungarians, was about a German mile and a half or around 11 kilometres.

★ The Finnish corresponding unit, 'virsta', was 1068.8 m. Ten ''virsta'' made one 'peninkulma' (literally "hound's hearing", a distance a dog's bark can be heard in still air), 10.688 km. Today ''peninkulma'' refers to 10 km in Finnish colloquial usage (compare ''mil'' in Norwegian and Swedish usage).

★ The swimmer's mile is 1500 meters or 30 laps in a 25 meter pool. This (roughly) converts to 1650 yards in a 25 yard pool (33 laps), the standard distance for intercollegiate competition in the United States.

★ A 'country mile' is used colloquially to denote a very long distance.

See also

★ Systems of measurement

★ Fibonacci sequence application: convert to kilometers

★ Four-minute mile

★ Imperial units

★ League

★ Square mile

★ U.S. customary units

References

'Of Divers Measures', in Laurence Echard, 1741, ''The Gazetteer's or Newsman's Interpreter'', London: Ballard et al. (first published 1703)
1. Smith, Dictionary of Greek and Roman Antiquities, page 762

External links

★ NIST General Tables of Units of Measurement

★ Online conversion

★ The Nautical Mile in Freeport, New York