Arabic mile
Template:Short description The Arab, Arabic, or Arabian mile (Template:Langx, al-mīl) was a historical Arabic unit of length. Its precise length is disputed, lying between Script error: No such module "convert". and Script error: No such module "convert".. It was used by medieval Arab geographers and astronomers. The predecessor of the modern nautical mile, it extended the Roman mile 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 cubits 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's surveying cubit, it was 1,925 meters long or Script error: No such module "convert".[1]
During the Umayyad period (661–750), the "Umayyad mile" was roughly equivalent to Script error: No such module "convert"., or a little more than Script error: No such module "convert"., or about 2 biblical miles, for every Umayyad mile.[2]
Al-Ma'mun's arc measurement
Around 830 AD, Caliph Al-Ma'mun commissioned a group of Muslim astronomers and Muslim geographers to perform an arc measurement from Tadmur (Palmyra) to Raqqa, in modern Syria. They found the cities to be separated by one degree of latitude and the corresponding meridian arc distance to be <templatestyles src="Fraction/styles.css" />66+2⁄3 Arabic miles and thus calculated the Earth's circumference to be Script error: No such module "convert"..[3] 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 <templatestyles src="Fraction/styles.css" />56+2⁄3 Arabic miles (Script error: No such module "convert". per degree), which corresponds to a circumference of Script error: No such module "convert"., very close to the current values of Script error: No such module "convert". per degree and Script error: No such module "convert". circumference, respectively.[1][4]
See also
Notes
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- ↑ a b Edward S. Kennedy, Mathematical Geography, pp=187–8, in Script error: No such module "Footnotes".
- ↑ See: p. 608 (note 11) in: Script error: No such module "Citation/CS1".
- ↑ Gharā'ib al-funūn wa-mulah al-`uyūn (The Book of Curiosities of the Sciences and Marvels for the Eyes), 2.1 "On the mensuration of the Earth and its division into seven climes, as related by Ptolemy and others," (ff. 22b-23a)[1]
- ↑ 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) [2]
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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.
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