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Mile
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A mile is a unit of length, usually used to measure distance, in a number of different systems. In contemporary English contexts, mile most commonly refers to the statute mile of 5,280 feet (exactly 1,609.344 meters) or the nautical mile of 1,852 meters (about 6,076.1 ft).
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Encyclopedia
| mile |
|---|
| statute | nautical |
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| 1.609344 km | 1.852 km | | 1,609.344 m | 1,852 m | | 1,760 yd | 2,025.372 yd | | 5,280 ft | 6,076.115 ft | | 63,360 in | 72,913.4 in | |
A mile is a unit of length, usually used to measure distance, in a number of different systems. In contemporary English contexts, mile most commonly refers to the statute mile of 5,280 feet (exactly 1,609.344 meters) or the nautical mile of 1,852 meters (about 6,076.1 ft). There are many other historical miles, and similar units in other systems translated as miles in English, varying between one and fifteen kilometers. It is about a third of the old measurement, a League.
There have been several abbreviations for mile (with and without trailing period): mi, ml, m, M. In the United States, the National Institute of Standards and Technology now uses and recommends mi but in everyday usage (at least in the United States and in the United Kingdom) usages such as miles per hour and miles per gallon are almost always abbreviated as mph or mpg (rather than mi/h or mi/gal).
The formula "multiply by 8 and divide by 5" to convert international miles to kilometers gives a conversion of 1.6, accurate to 0.6%, which is a useful approximation.
Roman mile
In Roman times, a unit of measuring distance was the pedes, meaning "going on foot" or "a foot soldier". Five pedes were equivalent to one passus. The unit of long distance (literally "a thousand paces" in Latin, with one pace being equal to two steps) was first used by the Romans and denoted a distance of 1,000 paces or 5,000 Roman feet, and corresponded to about 1,479 meters, or 1,617 modern yards. This unit is now known as the Roman mile.
This unit spread throughout the Roman empire, often with modifications to fit local systems of measurements.
Statute mile
The statute mile is the distance typically meant when the word mile is used without other qualifying words, though in nautical, aviation, and polar exploration the nautical mile might be used without qualification.
The current definition of a mile as 5,280 feet (as opposed to 5,000) dates to the 13th century, and was confirmed by statute in the reign of Queen Elizabeth I; However, various English-speaking countries maintained independent length standards for the yard, which differed by small but measurable amounts, and thus led to miles of slightly different lengths. This was resolved in 1959 with the definition of the current international mile by Australia, Canada, New Zealand, South Africa, the United Kingdom, and the United States.
The international mile being 5,280 feet is defined in terms of the international foot (0.3048 m), while the statute miles of the various English-speaking countries were based on the national foot of each country.
The name statute mile originates from a statute of the Parliament of England in 1592 during the reign of Elizabeth I. This defined the statute mile as 5,280 ft or 1,760 yards; or 63,360 inches. Both statute and international miles are divided into eight furlongs. In turn a furlong is ten chains; a chain is 22 yards and a yard is three feet, making up 5,280 ft.
A national statute mile still in limited use is the U.S. survey mile of 5,280 survey feet which is slightly longer at approximately 1,609.347219 meters (1 international mile is exactly 0.999998 survey mile). Thompson and Taylor of the National Institute of Standards and Technology give many unit conversion factors, but for statute mile, only state "8 fur = 1 U.S. survey mile (also called 'statute mile') = 1 mi = 5280 ft" (in that section, abbreviations in italic type indicates the U.S. survey foot or U.S. survey mile). Nowhere in that publication is the name "statute mile" applied to the international mile.
Other miles in Britain and Ireland
Before the statute of the English parliament, there was confusion on the length of the "mile". The Irish mile was 6,720 feet and the Scottish mile was 5,951 feet. Perhaps the earliest tables of English linear measures, Arnold's Customs of London (c. 1500) indicates a mile consisted of 8 furlongs, each of 625 feet, for a total of 5,000 feet. For other "miles" see the list below.
Nautical mile
The nautical mile was originally defined as one minute of arc along a meridian of the Earth. It is a convenient reference since it is fairly constant at all latitudes, in contrast with degrees of longitude which vary from 1 NM at the equator to zero at the poles.
Navigators use dividers to step off the distance between two points on the navigational chart, then place the open dividers against the minutes-of-latitude scale at the edge of the chart, and read off the distance in nautical miles. Since it is now known that the Earth is not perfectly spherical but an oblate spheroid, the length derived from this method varies slightly from the equator to the poles. For instance, using the WGS84 Ellipsoid, the commonly accepted Earth model for many purposes today, one minute of latitude at the WGS84 equator is 6,087 feet and at the poles is 6,067 feet. On average it is about 6,076 feet (about 1852 meters or 1.15 statute miles).
In the United States of America, the nautical mile was defined in the nineteenth century as 6,080.2 feet (1,853.249 m), whereas in the United Kingdom 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 meters.
The nautical mile per hour is known as the knot. Nautical miles and knots are almost universally used for aeronautical and maritime navigation because of their relationship with degrees and minutes of latitude and the convenience of using the latitude scale on a map for distance measuring.
Grid system
Cities in the western United States often have streets laid out by miles. Miami, Florida, Phoenix, Arizona and Las Vegas are three examples. Typically the largest streets are about one mile apart, with others at half-mile, quarter-mile intervals. Also in Manhattan (New York) 'streets' are almost exactly 20 per mile, while 'avenues' are about six per mile.
Other miles
- The Danish (traditional) was 24,000 Danish feet or 7532.5 meters. Sometimes it was interpreted as exactly 7.5 kilometers. It is the same as the north German (below).
- The was a traditional unit in German speaking countries, much longer than a western European mile. It was 24,000 German feet; the SI equivalent was 7586 meters in Austria or 7532.5 meters in northern Germany. There was a version known as the which was 4 Admiralty nautical miles, 7,412.7 meters, or 1/15 degree.
- In Norway and Sweden a mil is a unit of length which is equal to 10 kilometers and commonly used in everyday language. However in more formal situations, like on road signs and when there is risk of confusion with English miles, kilometers are used instead. The traditional Swedish spanned the range from 6000-14,485 meters, depending on province. It was however standardized in 1649 to 36,000 Swedish feet, or 10.687 kilometers. The Norwegian was 11.298 kilometers. When the metric system was introduced in the Norwegian-Swedish union in 1889, one standardized the to exactly 10 kilometers
- The Russian was a traditional Russian unit of distance, equal to 7 verst, or 7.468 km
- The (Croatian mile) is 11,130 metres = 11.13 kilometres = 1/10 of equator's degree., first time used by Jesuit Stjepan Glavac on map from 1673.
- The (also called ) (mile of Croatian Ban, Croatian mile) was 7586 metres=7.586 kilometres, or 24,000 feet..
- The data mile is used in radar-related subjects and is equal to 6,000 feet (1.8288 kilometers).
- The radar mile is a unit of time (in the same way that the light year is a unit of distance), equal to the time required for a radar pulse to travel a distance of two miles (one mile each way). Thus, the radar statute mile is 10.8 µs and the radar nautical mile is 12.4 µs.
- The term metric mile is used in sports such as athletics (track and field) and speed skating to denote a distance of 1.5 kilometers. In United States high school competition the term is sometimes used for a race of 1.6 kilometers.
Idioms
Even in countries that have moved from the Imperial to the Metric system (for example, Australia and New Zealand), the mile is still used in a variety of idioms. These include:
- A country mile is used colloquially to denote a very long distance.
- "A miss is as good as a mile" (failure by a narrow margin is no better than any other failure)
- "Give him an inch and he'll take a mile" (the person in question will become greedy if shown generosity)
- "Missed by a mile" (missed by a wide margin)
- "Talk a mile a minute" (speak at a rapid rate)
- "To go the extra mile" (to put in extra effort)
- "Miles away" (lost in thought, or daydreaming)
See also
External links
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