Abû Mahmûd Hâmîd ibn al Khidr al Khujandi (10th century) constructed an instrument, made of an arc of a sity degree of meridian, and called Suds al Fakhri, for the measurement of the obliquity of the ecliptic. It has a radius of about twenty metres, and surpassed all previous ones in size. This arc is placed on a wall, erected on the meridian.
Abu Mahmud Hamid ibn Khidr Khujandi
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