From: Thomas Hockey et al. (eds.). The Biographical Encyclopedia of Astronomers, Springer Reference. New York: Springer, 2007, pp. 1122-1123 |
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Taqī al‐Dīn
Abū Bakr Muḥammad
ibn Zayn al‐Dīn Maʿrūf al‐Dimashqī al‐Ḥanafī
İhsan Fazlıoğlu
Born Damascus, (Syria),
14 June 1526
Died Istanbul, (Turkey),
1585
Taqī
al‐Dīn was the founder and the director of the Istanbul Observatory
and worked in the fields of mathematics, astronomy, optics, and mechanics.
He made various astronomical instruments and was the first astronomer to use
an automatic–mechanical clock for his astronomical observations. He advanced
the arithmetic of decimal fractions and used them in the calculation of astronomical
tables.
Taqī
al‐Din began his studies, as was normal, with the basic religious sciences
and Arabic. Later on, he continued his religious studies and studied the mathematical
sciences with scholars in Damascus and Egypt, including most significantly
his father. It is probable that Taqī al‐Dīn's teacher in mathematics
was Shihāb al‐Dīn al‐Ghazzī whereas the one in
astronomy was Muḥammad ibn Abī al‐Fatḥ
al‐Ṣūfī. Taqī al‐Dīn
himself states in several of the forewords to his books that he was particularly
interested in the mathematical sciences during his education.
Taqī
al‐Dīn, after completing his education, taught for a short while
at various madrasas (schools) in Damascus. He, together with his father
Maʿrūf Afandī,
came to Istanbul around the year 1550 where he benefited from his association
with a number of prominent scholars. Taqī al‐Dīn would shortly
return to Egypt where he spent most of the next 20 years. A brief trip back
to Istanbul, also around 1550, brought him into the company of the Grand Vizier
Samīz ʿAlī
Pasha, who allowed him to use his private library and clock collection. Taqī
al‐Dīn would benefit from this association when ʿAlī Pasha was appointed governor of Egypt, where he held positions
as a teacher and judge (qāḍī)
in Egypt. Encouraged to deal with mathematics and astronomy by a grandson
of ʿAlī Qūshjī, who collected and gave
Taqī al‐Dīn works by his grandfather, by Jamshīd
al‐Kāshī, and by Qāḍīzāde,
as well as various observation instruments, Taqī al‐Dīn undertook
a serious pursuit of astronomy and mathematics. While a judge in Tinnīn,
Egypt, he made astronomical observations by means of an astronomical instrument
that he mounted in a well that was 25‐m deep.
Taqī
al‐Dīn returned to Istanbul in 1570 and was appointed head astronomer
(Müneccimbası) by Sultan Selīm II upon the death of Muṣṭafā ibn ʿAlī
al‐Muwaqqit in 1571. He continued his observations in a building
situated on a height overlooking Tophane or in Galata Tower and gained the
support of several high officials. This led to an imperial edict by Sultan
Murad III in early 1579 to build an observatory, which was located on a height
overlooking Tophane where the French palace is located today. Important astronomical
books and instruments were collected there. Little is known about the size,
shape, and so on, but we do have magnificent depictions of the scholars at
work and of the astronomical instruments in use (in Ālāt‐i
raṣadiyya li‐Zij‐i
Shāhinshāhiyya [Istanbul Univesity, TY, MS 1993] and in ʿAlāʾ al‐Dīn
Manṣūr al‐Shīrāzī's Shāhinshahnāme
[Istanbul University, TY, MS 1404]). Apart from the observatory building,
we hear of a well called çah‐i raṣad that was also used by
Taqī al‐Dīn. Unfortunately the observatory did not last long.
Due to political reasons, as well as Taqī al‐Dīn's incorrect
astrological prognostications, it was demolished by the state on 22 January
1580.
Taqī
al‐Dīn's most important work in astronomy is entitled Sidrat
muntahā al‐afkār fī malakūt al‐falak al‐dawwār
(= al‐Zīj al‐Shāhinshāhī). This work
was prepared according to the results of the observations in Egypt and Istanbul
in order to correct and complete Zīj‐i Ulugh Beg, a project
originally conceived in Egypt and furthered by the building of the Istanbul
Observatory. In the first 40 pages of the work, Taqī al‐Dīn
deals with trigonometric calculation. This is followed by discussions of astronomical
clocks, heavenly circles, and so forth. In the following parts, he treats
observational instruments and their use, the observations of lunar and solar
motions, and trigonometric functions calculated according to sexagesimal.
As was normal in the Islamic astronomical tradition, Taqī al‐Dīn
used trigonometric functions such as sine, cosine, tangent, and cotangent
rather than chords. Following the work done at the Samarqand Observatory,
he developed a new method to find the exact value of sin 1°, which Jamshīd
al‐Kāshī had put into the form of an equation of third degree.
Additionally, Taqī al‐Dīn employed the method of “three observation
points,” which he was the first to use for calculating solar parameters; apparently
Tycho Brahe
was aware of his work. For determining the longitudes and latitudes of the
fixed stars, he used Venus, Aldebaran, and α Virginis (Spica), which
are near the ecliptic (rather than the Moon), as reference stars. As a result
of his observations, he found the eccentricity of the Sun to be 2° 0'
and the annual motion of apogee 63″. Taqī al‐Dīn's values turn out to be more precise
than those of Nicolaus
Copernicus and Brahe. This provides evidence for the precision of
Taqī al‐Dīn's methods of observation and calculation. It is
thus a pity that the destruction of the observatory meant that Taqī al‐Dīn
was unable to complete his observation program. Indeed in the absence of a
conclusion to this Zīj, it can probably be concluded that the
book was never completed.
Taqī
al‐Dīn's second most important work on astronomy is a zīj
entitled Jarīdat al‐durar wa kharīdat al‐fikar.
In this work, for the first time we find the use of decimal fractions in trigonometric
functions. He also prepared tangent and cotangent tables. Moreover, in this
zīj, as in another of his zījes entitled Tashīl
zīj al‐aʿshāriyya
al‐shāhinshāhiyya, Taqī al‐Dīn gave the
parts of degree of curves and angles in decimal fractions and carried out
the calculations accordingly. Excluding the table of fixed stars, all the
astronomical tables in this zīj were prepared using decimal fractions.
In addition,
Taqī al‐Dīn has some other astronomical works of secondary
importance. One of them is Dustūr al‐tarjīḥ li‐qawāʿid al‐tasṭīḥ, which is about the projection
of a sphere onto a plane as well as other topics in geometry. Another of his
works is Rayḥānat al‐rūḥ fī rasm al‐sāʿāt ʿalā
mustawī al‐suṭūḥ, which deals with sundials
drawn on marble surfaces and their features. This book was commented upon
by his student Sirāj al‐Dīn ʿUmar ibn
Muḥammad al‐Fāriskūrī
(died: 1610) under the title Nafḥ al‐fuyūḥ bi‐sharḥ
rayḥānat al‐rūḥ;
the commentary was translated into Turkish by an unknown writer in the beginning
of the 17th century.
In addition to his 20 books on astronomy, Taqī al‐Dīn
wrote one book on medicine and zoology, three on physics‐mechanics,
and five on mathematics. He has a monograph entitled Risāla fī
ʿamal al‐mīzān
al‐ṭabīʿī on the specific gravity of substances
and Archimedes'
hydrostatic experiments. All of his books are in Arabic.
Taqī
al‐Dīn's works on physics and mechanics, besides being interesting
in their own right, also have connections with astronomy. In 1559 while in
Nablus, he wrote his al‐Kawākib al‐durriyya fī waḍʿ al‐bankāmāt
al‐dawriyya, which dealt with mechanical‐automatic
clocks for the first time in the Islamic and Ottoman world. In the foreword,
Taqī al‐Dīn mentions that he benefited from using Samiz ʿAlī Pasha's private library and his collection of European mechanical
clocks. In this work, Taqī al‐Dīn discusses various mechanical
clocks from a geometrical–mechanical perspective. His second book on mechanics
is the one he wrote when he was 26, al‐Ṭuruq al‐saniyya fī al‐ālāt
al‐rūḥāniyya. In this work, Taqī
al‐Dīn focuses on the geometrical‐mechanical structure of
clocks previously examined by the Banū
Mūsā and Abū al‐ʿIzz al‐Jazarī. In the field of physics and optics, Taqī
al‐Dīn wrote Nawr ḥadīqat
al‐abṣar wa‐nūr
ḥaqīqat
al‐Anẓar, which dealt with the
structure of light, its diffusion and global refraction, and the relation
between light and color.
In
his mathematical treatises, Taqī al‐Dīn dealt with various
aspects of trigonometry, geometry, algebra, and arithmetic. In the latter,
he carried on the work of Kāshī in developing the arithmetic of
decimal fractions both theoretically and practically.
Taqī
al‐Dīn was a successor to the great school of Samarqand and, following
the lead of ʿAlī
Qūshjī, tended toward a more purely mathematical approach in his
scientific work that was beginning to abandon Aristotelian physics and metaphysics.
Taqī al‐Din's most significant achievement in the history of Islamic
and Ottoman astronomy is his foundation of the Istanbul Observatory and his
activities there. Besides using established instruments and techniques, he
developed a number of new ones as well, including his use of the automatic–mechanical
clock. Carrying on the work of his Islamic predecessors, Taqī al‐Dīn's
application of decimal fractions to trigonometry and astronomy stands as another
important contribution to astronomy and mathematics.
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