Ibn Qurrah


Thabit ibn Qurrah, known in the West as Thebit, is known for his work on mechanics, astronomy, pure mathematics and geometry. Thabit ibn Qurrah ibn Marwan al-Harrani was born in 836 C.E. at Harran (present Turkey) and died in Baghdad in 901 C.E. He joined the scientific team of the great Muslim mathematician Muhammad Ibn Musa Ibn Shakir at Baghdad, which was established by the Abbasid Caliphs.

Thabit was a pioneer in extending the concept of traditional geometry to geometrical algebra and proposed theories that led to the development of non-Euclidean geometry, spherical trigonometry, integral calculus and real numbers. He used arithmetic terminology to study several aspects of conic sections (parabola and ellipse). His algorithm for computing the surface area and volume of solids is in fact what we came to know later as the integral calculus.

Thabit’s original work on Mechanics and Physics involves examining conditions of equilibrium of bodies, beams and levers. Some historians have recognized him as the Founder of Statics. He was among the early critics of Ptolemaic views on astronomy. He also criticized several theorems of Euclid’s elements and proposed important improvements. Thabit added the ninth sphere to Ptolemic astronomy. Some early investigators criticized his work on ‘Trepidation of Equinoxes’ and several centuries later Tycho Brahe (1546-1601) improved upon his work.

Thabit analyzed several problems on the movements of sun and moon and wrote treatises on sundials. Beer and Madler in their famous work Der Mond (1837) mention a surface feature of the moon after Thabit (Thebit). It is a prominent circular plain thirty miles in diameter in Section No. 8. The intrusion of a small circular plain has disfigured its circular wall. A small crater has thrust itself in on the eastern side of this plain.

Thabit‘s books on mathematics, astronomy and medicine have survived. He translated many Greek and Syrian works on Science into Arabic while in the service of Khalifah Al-Mu’tadid. Among his translations into Arabic are the Ptolemy’s Almagest, Euclid’s Elements of Geometry, Apollonius‘s book on conic sections, and some of Archimedes’ works. In the Middle Ages, Gerard of Cremona translated some of his books into Latin.

Thabit left his legacy with sons (Ibrahim and Sinan), grandsons (Thabit and Ibrahim) and great grandson (Abu al-Faraj) who also contributed substantially to our knowledge of geometry, astronomy and medicine. His son Sinan conducted regular examination (certification) of medical practioners begining in 931 C.E. and awarded eight hundred certificates to medical doctors. Sinan also instituted traveling hospitals and inspected prisons to assure adequate health care.