| Chalid Ben Abdulmelik |
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Information AboutChalid Ben Abdulmelik |
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Together with Ali Ben Isa in 827 , he measured at 35 Degree s north geographical Latitude , in the valley of the Tigris , the Length of a Meridian and thus the Earth 's Circumference , getting a result of 40,248 Km (or, according to other sources, 41,436 km). The two researchers measured in Arabian Ell , and determined the geographical latitudes of the end points they used from the Star Altitudes in a celestial Horizontal Coordinate System . We believe that 1 Arabian ell was 49 1/3 Cm . Thus, they found the length of 1° of meridian to be 111.8 km (115.1 km), which differs from the actual value by 850 Metre s. |
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