Two treatises by Ibn al-Haytham on the meridian line, translated from the edition by Fuat Sezgin

Abstract

This paper contains an annotated English translation of the two surviving treatises by Ibn al-Haytham (ca. 965-1041) on the determination of the meridian line. These very technical treatises survive in an Arabic manuscript in Berlin, and they were published by Fuat Sezgin in an excellent Arabic edition which appeared in this journal in 1986. The edition has not been translated before, but it has served as a source for a reconstruction of Ibn al-Haytham's instrument for the determination of the meridian line. A study of Sezgin's editions, which are translated in this paper, shows that the reconstructed instrument gives an incorrect representation of Ibn al-Haytham's ideas.