ALHAZEN

, Allacen, or Abdilazum, was a learned Arabian, who lived in Spain about the year 1100, according to his editor Risner, and Weidler. He wrote upon Astrology; and his work upon Optics was printed, in Latin, at Basil, in 1572, under the title of Opticæ Thesaurus, by Risner. Alhazen was the first who shewed the importance of refractions in astronomy, so little known to the ancients. He is also the first author who has treated on the twilight, upon which he wrote a work, in which he also speaks of the height of the clouds.