Biruni, Al-

(full name, Abu-al-Rayhan Muhammad ibn-Ahmad al-Biruni). Born Oct. 4, 973; died Dec. 13, 1048 (according to other data, after 1050). Middle Asian scholar and encyclopedist. Wrote in Arabic. Born in Khwarizm.

In 1018 (or 1017), Mahmud Gaznavi brought al-Biruni to Ghazni, where he remained for the rest of his life. Al-Biruni’s works were in the fields of mathematics, astronomy, physics, botany, geography, general geology, mineralogy, history, and chronology. In the Chronology of Ancient Nations, al-Biruni provides a detailed description of Arabic, Persian, Hebrew, Greek, and other calendrical systems. His treatise The Key to Astronomy has not been found, but his brief Introduction to the Elements of the Art of Astrology has been preserved. The latter consists of a popular exposition of basic mathematics and astronomy. In A Book on the Location of Chords in the Circle he developed a series of original mathematical methods and proofs. In a lengthy work on mathematical and descriptive geography, The Masudi Canon, he provided a trigonometric method for the determination of longitudes, resembling modern geodesic triangulation methods. There is also information pertaining to problems of trisecting an angle, doubling a cube, and to the solution of third degree equations. Al-Biruni was the first in the Middle East to express the possibility that the earth rotates around the sun and to determine the earth’s circumference. He wrote an extensive work on the topography of Middle Asia; of particular interest are his studies on the changing course of the Amu Darya River in the distant geological past. In his treatise Rules on Determining the Specific Gravity of Minerals, Biruni produced a series of numerical data very close to modern determinations.

His exceptional erudition was combined with views that were very progressive for his time. He had an ironic attitude toward religious superstitions and spoke out against enmity between peoples. Biruni’s historical work on India, An Explanation of Indian Doctrines Accepted or Rejected by Reason, materials for which he gathered during Mahmud’s Indian campaigns, is an important source on Indian history in the early medieval period.