The Arab, Arabic, or Arabian mile (, ''al-mīl'') was a historical Arabic unit of

length Length is a measure of distance. In the International System of Quantities, length is a quantity with Dimension (physical quantity), dimension distance. In most systems of measurement a Base unit (measurement), base unit for length is chosen, ...

. Its precise length is disputed, lying between and . It was used by medieval Arab geographers and

astronomers An astronomer is a scientist in the field of astronomy who focuses on a specific question or field outside the scope of Earth. Astronomers observe astronomical objects, such as stars, planets, moons, comets and galaxies – in either observ ...

. The predecessor of the modern

nautical mile A nautical mile is a unit of length used in air, marine, and space navigation, and for the definition of territorial waters. Historically, it was defined as the meridian arc length corresponding to one minute ( of a degree) of latitude at t ...

, it extended the

Roman mile The mile, sometimes the international mile or statute mile to distinguish it from other miles, is a British imperial unit and United States customary unit of length; both are based on the older English unit of length equal to 5,280 English ...

to fit an astronomical approximation of 1 minute of an arc of latitude measured along a north–south meridian. The distance between two pillars whose latitudes differed by 1 degree in a north–south direction was measured using sighting pegs along a flat desert plane. There were 4,000

cubit The cubit is an ancient unit of length based on the distance from the elbow to the tip of the middle finger. It was primarily associated with the Sumerians, Egyptians, and Israelites. The term ''cubit'' is found in the Bible regarding Noah ...

s in an Arabic mile. If al-Farghani used the legal cubit as his unit of measurement, then an Arabic mile was 1,995 meters long. If he used

al-Ma'mun Abū al-ʿAbbās Abd Allāh ibn Hārūn al-Maʾmūn (; 14 September 786 – 9 August 833), better known by his regnal name al-Ma'mun (), was the seventh Abbasid caliph, who reigned from 813 until his death in 833. His leadership was marked by t ...

's surveying cubit, it was 1,925 meters long or During the Umayyad period (661–750), the "Umayyad mile" was roughly equivalent to , or a little more than , or about 2 biblical miles, for every Umayyad mile.

Al-Ma'mun's arc measurement

Around 830 AD, Caliph

Al-Ma'mun Abū al-ʿAbbās Abd Allāh ibn Hārūn al-Maʾmūn (; 14 September 786 – 9 August 833), better known by his regnal name al-Ma'mun (), was the seventh Abbasid caliph, who reigned from 813 until his death in 833. His leadership was marked by t ...

commissioned a group of Muslim astronomers and Muslim geographers to perform an

arc measurement Arc measurement, sometimes called degree measurement (), is the astrogeodetic technique of determining the radius of Earth and, by Circumference#Circle, extension, Earth's circumference, its circumference. More specifically, it seeks to determine ...

from Tadmur (

Palmyra Palmyra ( ; Palmyrene dialect, Palmyrene: (), romanized: ''Tadmor''; ) is an ancient city in central Syria. It is located in the eastern part of the Levant, and archaeological finds date back to the Neolithic period, and documents first menti ...

) to

Raqqa Raqqa (, also , Kurdish language, Kurdish: ''Reqa'') is a city in Syria on the North bank of the Euphrates River, about east of Aleppo. It is located east of the Tabqa Dam, Syria's largest dam. The Hellenistic, Roman, and Byzantine city and b ...

, in modern Syria. They found the cities to be separated by one degree of

latitude In geography, latitude is a geographic coordinate system, geographic coordinate that specifies the north-south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from −90° at t ...

and the corresponding

meridian arc In geodesy and navigation, a meridian arc is the curve (geometry), curve between two points near the Earth's surface having the same longitude. The term may refer either to a arc (geometry), segment of the meridian (geography), meridian, or to its ...

distance to be Arabic miles and thus calculated the

Earth's circumference Earth's circumference is the distance around Earth. Measured around the equator, it is . Measured passing through the poles, the circumference is . Treating the Earth as a sphere, its circumference would be its single most important measuremen ...

to be . Using this measurement, knowing that earth's circumference is 40,007.683 km makes the Arabic mile little more than 1,666.994 metres. With Firuzabadi in his famous dictionary saying that a mile equals 3000 old dhira (ie cubit) this makes the dhira about 0.5556647 metres which is consistent with the tradition that kaaba height's is 27 dhira and its current height of 15 metres. Another estimate given by his astronomers was Arabic miles ( per degree), which corresponds to a circumference of , very close to the current values of per degree and circumference, respectively.Edward S. Kennedy, ''Mathematical Geography'', pp=187–8, in '' Gharā'ib al-funūn wa-mulah al-+uyūn'', 2.1 "On the mensuration of the Earth and its division into seven Climes, as related by Ptolemy and others", (ff. 22b-23

/ref>

Notes

Bibliography

*Paul Lunde. “Al-Faraghani and the Short Degree.” The Middle East and the Age of Discovery Aramco World Magazine Exhibition Issue, 43:3. pp. 15–17. * {{DEFAULTSORT:Arab Mile Obsolete units of measurement Geography in the medieval Islamic world Units of length

Al-Ma'mun's arc measurement

See also

Notes

Bibliography