THABIT IBN QURRAH (THEBIT) (836  901 C.E.)
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 alHarrani
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 nonEuclidean 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 (15461601) 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
AlMu'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
alFaraj) 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.
