an Arabic prince of Batan in Mesopotamia, and a celebrated astronomer, who lived about the year of Christ 880, as appears by his observations. He is also called Mubammed ben Geber, Albataani, Mahomet the son of Geber, and Mubamedes Arategenis. He made astronomical observations at Antioch, and at Racah or Arafa, a town of Chaldea. He is highly spoken of by Dr Halley as a man of admirable genius, and an excellent observer.

Instead of the tables of Ptolemy which were imperfect, he computed new ones; these were adapted to the meridian of Arafa or Racah, and were long used as the best among the Arabs. Albategni composed in Arabic a work under the title of The Science of the Stars, comprising all parts of astronomy, according to his own observations and those of Ptolemy. This work was translated into Latin by Plato of Tibur, and published at Nuremberg in 1537, with some additions and demonstrations of Regiomontanus. It was reprinted at Bologna in 1645, with this author's notes. Dr Halley detected many faults in these editions: Philos. Trans. for 1693, No. 204. In this work, Albategni gives the motion of the sun's apogee since Ptolemy's time, as well as the motion of the stars, which he makes makes one degree in 70 years. He made the longitude of the first star of Aries to be $18^\circ 2'$; and the obliquity of the ecliptic $23^\circ 35'$. Upon Albategni's observations were founded the Alphonsine tables of the moon's motions. *(Hutton's Math. Dict.)*