From: Thomas Hockey et al. (eds.). The Biographical Encyclopedia of Astronomers, Springer Reference. New York: Springer, 2007, pp. 455-457 |
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Ḥabash al‐Ḥāsib: Abū Jaʿfar Aḥmad ibn ʿAbd Allāh al‐Marwazī
François Charette
Died probably Samarra,
(Iraq), after 869
Ḥabash al‐Ḥāsib (literally, “Ḥabash the calculator,” with the intended
meaning of “mathematical astronomer”) was one of the most original and most
influential Muslim astronomers of the formative period of Islamic astronomy.
The dates of his birth and death are not known, but according to the bibliographer
Ibn al‐Nadīm he died as a centenarian. Ḥabash was closely associated with the ʿAbbāsid court; he was active in Baghdad during the reign of Caliph
Maʾmūn (813–833). Later, he
lived and worked in Samarra, which in 838, became the new administrative capital
of the ʿAbbāsid Empire.
Ḥabash's biography is yet to be
definitively established. The bibliographer Ibn al‐Nadīm (died:
995) mentions Ḥabash as a scientist active at the time of
Maʾmūn, and Ibn al‐Qifṭī
(died: 1248) adds that he also lived under the reign of al‐Muʿtaṣim. In his own account of the
achievements of the aṣḥāb al‐mumtaḥan –
the group of scholars involved in the observational project sponsored by Caliph
Maʾmūn whose objective was to check the parameters of Ptolemy's
Almagest – Ḥabash does not present himself as one of
their protagonists, although he was certainly in close contact with them.
The earliest certain date associated with him is given by Ibn
Yūnus, who reports an observation conducted by Ḥabash in Baghdad in the year 829/830 (i.
e., 4 years before the death of Maʾmūn). This is also the date
associated with many other mumtaḥan observations and with
the mumtaḥan star‐table.
Ibn
al‐Qifṭī
attributes a zīj (astronomical handbook) to Ḥabash. This was compiled when he was a young
man in the tradition of the Indian Sindhind, and was based upon the
zīj of Khwārizmī.
Also ascribed to him is another smaller work, the Zīj al‐Shāh,
probably following the same Pahlavi tradition as the eponym work by Fazārī.
The composition of those two non‐Ptolemaic zījes must have
occurred before 829/830, the year when the mumtaḥan observational program
was inaugurated. But Ḥabash is best known to his contemporaries and successors for his authorship
of a third zīj, whose content is almost entirely Ptolemaic, and
which became known as “the” zīj of Ḥabash.
In the introduction to this latter zīj, Ḥabash informs his readers that after Maʾmūn's
death he took upon himself the task of revising the observational data gathered
by the “mumtaḥan astronomers.” Hence, inspired by Ptolemy's methodology,
he conducted his own observations of the Sun and Moon, and also made repeated
observations of the remaining planets at specific times. The latest dates
associated with Ḥabash are recorded in his zīj – 22 April 849, 17 November
860, and 15 September 868. These dates coincide with the reigns of Caliph
al‐Mutawakkil (reigned: 847–861) and of his third short‐lived
successor al‐Muʿtazz
(reigned: 866–869). We can assume that the zīj was finalized after
the year 869 and represented Ḥabash's
ultimate achievement. A further indication of this is the fact that Ḥabash
uses an obliquity of the ecliptic of 23° 35′, a value observed by
the Banū Mūsā in Samarra
in the year 868/869. He could not have been more than circa 75 years
old at that time, which would then imply that he was not born before circa
796. The period 796–894, in fact, seems to be the most reasonable estimate
for his life span, and this would make him belong to the same generation as
Abū Maʿshar
and Kindī. The usual modern references
to him as flourishing circa 830 would seem to correspond in actuality
to the earliest period of his life.
To
summarize, we can divide Ḥabash's scientific career into the following four distinct periods:
1. |
The early, formative period in Baghdad (circa
815–829), during which he became acquainted with the Indian and Persian
astronomical systems through the works of Fazārī and Khwārizmī,
and composed two zījes based upon these systems. |
2. |
The mumtaḥan
period (829–834), during which he presumably had close contacts with
the mumtaḥan
group of astronomers in Baghdad and Damascus, and benefited from their
new observations and insights. During this crucial period, the superiority
of Ptolemy's system became gradually obvious to most specialists. With
the resulting consensus in favor of Ptolemaic astronomy and the consequent
abandonment of Persian and Indian theories, Islamic astronomy reached
a new, stable phase of its development. |
3. |
The
post‐mumtaḥan period, beginning after the death of Maʾmūn
in August 833, and possibly based in Damascus, during which Ḥabash pursued his own observational program following the mumtaḥan tradition. |
4. |
The Samarra period, covering the last half of his career,
during which he finalized his Ptolemaic zīj and composed
most of his astronomical works that are now extant. |
The Ptolemaic zīj of Ḥabash,
the only one that is extant, is known under four different names – al‐Zīj
al‐Mumtaḥan
and al‐Zīj al‐Maʾmūnī (because it is
based on the observational program of the mumtaḥan group under the sponsorship
of Maʾmūn), al‐Zīj al‐Dimashqī (presumably
because it was also based on observations conducted by Ḥabash in Damascus), and al‐Zīj
al‐ʿArabī (because it is based
on the Arabic Hijra calendar). There is absolutely no evidence to support
the contention that the above appellations might refer to more than a single
work. Every reference to “the zīj of Ḥabash” encountered in later sources (notably
Bīrūnī and Ibn Yūnus) is in accord with the single
version of the zīj by this author that is preserved for us. There
is an instance where Bīrūnī mentions the zīj of
Ḥabash in general terms, and later characterizes
the same work with the epithet al‐mumtaḥan. This zīj
is the earliest independently compiled Ptolemaic astronomical handbook in
the Arabic language that is preserved in its entirety. Undoubtedly, it was
also one of the most influential zījes of its generation. Indeed,
Bīrūnī, in the early (Khwārizmian) period of his life,
utilized it for his own astronomical practice. Although Ḥabash follows Ptolemy's models and procedures
very closely, he does introduce several new, improved parameters as well as
an impressive amount of original computational methods, some of them undoubtedly
of Indian origin or inspiration. His zīj also contains a set of
auxiliary trigonometric tables, called jadwal al‐taqwīm,
which are of singular importance in the history of trigonometry.
Two copies of this zīj are available, one preserved in
Istanbul, which preserves fairly well the original text, and a second one
in Berlin. The latter is a recension of the original, mixed with materials
due to various later astronomers. (A table of concordance with the Istanbul
MS is appended to M. Debarnot's survey of the Istanbul MS.) Unfortunately,
Ḥabash's zīj is yet to be published.
Another work of Ḥabash, his Book of Bodies and Distances,
is in fact devoted to five different topics of scientific activity conducted
under the patronage of Maʾmūn, including an interesting report on
the geodetic expedition to determine the radius of the Earth (or equivalently
the length of 1° of the meridian). Ḥabash also devoted several works to the topic
of astronomical instrumentation. An important treatise on the construction
of the melon astrolabe, which he probably invented and whose principle is
based on an “azimuthal equidistant” mapping, has been published by E. Kennedy
et al. (1999). An anonymous treatise on the construction of a highly
original but still unexplained universal instrument for timekeeping with the
stars, preserved in a unique and incomplete copy, has been published lately,
and Ḥabash's authorship has been established.
D. King recently suggested that this instrument could be a companion to the
medieval European universal dial known as navicula de venetiis, which
he hypothesizes to be, ultimately, of Islamic origin. Ḥabash also composed treatises on the use of the celestial globe, the
spherical astrolabe, and the armillary sphere.
Ḥabash's graphical procedure (a
so–called analemma construction) for determining the direction of Mecca (qibla)
is preserved in a letter of Bīrūnī to an Abū Saʿīd
(most probably Sijzī), in which the contents of Ḥabash's treatise – not extant
in its original form but incorporated in his zīj – are summarized.
Among several works of his that have not survived are treatises on the construction
of the standard planispheric astrolabe, on the prediction of lunar crescent
visibility, on the construction of sundials, and on some geometrical problem;
also lost are his two critical reports on the observations conducted by the
mumtaḥan group in Baghdad and
Damascus.
Al‐Hāshimī,
ʿAlī
ibn Sulaymān. The Book of the Reasons Behind Astronomical Tables (Kitāb
fī ʿilal
al‐zījāt). (A facsimile reproduction
of the unique Arabic text contained in the Bodleian MS Arch. Seld. A.11 with
a translation by Fuad I. Haddad and E. S. Kennedy and a commentary by David
Pingree and E. S. Kennedy. Delmar, New York: Scholars' Facsimiles and Reprints,
1981.)
Al‐Qifṭī,
Jamāl al‐Dīn (1903). Taʾrīkh al‐ḥukamāʾ,
edited by J. Lippert. Leipzig: Theodor Weicher.
Ali, Jamil (trans.) (1967).
The Determination of the Coordinates of Cities: Al‐Bīrūnī's
Taḥdīd al‐Amākin.
Beirut: American University of Beirut.
Berggren, J. L. (1980).
“A Comparison of Four Analemmas for Determining the Azimuth of the Qibla.”
Journal for the History of Arabic Science 4: 69–80.
——— (1991/1992). “Ḥabash's Analemma for Representing
Azimuth Circles on the Astrolabe.” Zeitschrift für Geschichte der Arabisch‐Islamischen
Wissenschaften 7: 23–30.
Caussin
de Perceval, Jean Jacques (1804). “Le livre de la grande table hakémite, observée
par … ebn Iounis.” Notices et extraits des manuscrits de la
Bibliothèque nationale 7: 16–240.
Charette,
François and Petra G. Schmidl (2001). “A Universal Plate for
Timekeeping by the Stars by Ḥabash al‐Ḥāsib: Text, Translation
and Preliminary Commentary.” Suhayl 2: 107–159.
Debarnot, Marie‐Thérèse (1987). “The Zīj of
Ḥabash
al‐Ḥāsib:
A Survey of MS Istanbul Yeni Cami 784/2.” In From Deferent to Equant: A
Volume of Studies in the History of Science in the Ancient and Medieval Near
East in Honour of E. S. Kennedy, edited by David A. King and George Saliba,
pp. 35–69. Annals of the New York Academy of Sciences, vol. 500. New York:
National Academy of Sciences.
Ibn al‐Nadīm (1970). The Fihrist of al‐Nadīm:
A Tenth‐Century Survey of Muslim Culture, edited and translated
by Bayard Dodge. 2 Vols. New York: Columbia University Press.
Irani, R. A. K. (1956). “The ‘Jadwal al‐Taqwīm’ of
Ḥabash
al‐Ḥāsib.”
Master's thesis, American University of Beirut, Mathematics Department.
Kennedy, E. S. (1956).
“A Survey of Islamic Astronomical Tables.” Transactions of the American
Philosophical Society, n.s., 46, pt. 2: 121–177. (Reprint, Philadelphia:
American Philosophical Society, 1989.)
Kennedy,
E. S., et al. Edited by David A. King and
Mary Helen Kennedy. Beirut: American University of Beirut, 1983. (Collection
of previously published papers, including numerous studies devoted to detailed
aspects of Ḥabash's astronomical achievements.)
Kennedy, E. S., P. Kunitzsch, and R. P. Lorch (1999). The
Melon‐Shaped Astrolabe in Arabic Astronomy. Texts edited with translation
and commentary. Stuttgart: Steiner.
King, David A. (1999).
World‐Maps for Finding the Direction and Distance to Mecca. Leiden:
E. J. Brill.
——— (2000). “Too Many
Cooks … A New Account of the Earliest Muslim Geodetic Measurements.” Suhayl
1: 207–241.
——— (2004). In
Synchrony with the Heavens: Studies in Astronomical Timekeeping and Instrumentation
in Medieval Islamic Civilization. Vol. 1, The Call of the Muezzin
(Studies I–IX). Leiden: E. J. Brill.
Langermann, Y. Tzvi (1985). “The Book of Bodies and Distances
of Ḥabash
al‐Ḥāsib.”
Centaurus 28: 108–128.
Lorch, Richard and Paul Kunitzsch (1985). “Ḥabash
al‐Ḥāsib's
Book on the Sphere and Its Use.” Zeitschrift für Geschichte der Arabisch‐Islamischen
Wissenschaften 2: 68–98.
Sayılı, Aydın (1955). “The Introductory Section
of Ḥabash's
Astronomical Tables Known as the ‘Damascene’ Zîj.” Ankara Üniversitesi
Dil ve Tarih–Coğrafya Fakültesi Dergisi 13: 132–151.
——— (1960). The Observatory in Islam. Ankara: Turkish
Historical Society.