| From: Thomas Hockey et al. (eds.). The Biographical Encyclopedia of Astronomers, Springer Reference. New York: Springer, 2007, pp. 563-564 |
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Ibn al‐Raqqām: Abū ʿAbd Allāh Muḥammad ibn Ibrāhīm ibn ʿAlī ibn Aḥmad ibn Yūsuf al‐Mursī al‐Andalusī al‐Tūnisī al‐Awsī ibn al‐Raqqām
Josep Casulleras
Died Granada (Spain),
27 May 1315
Ibn
al‐Raqqām was a prolific author who wrote on numerous branches
of learning. According to the Andalusian historian Ibn al‐Khaṭīb (1313–1374), he was
a versatile master (shaykh), unique in his time for his skills in arithmetic,
geometry, medicine, astronomy, and other disciplines. Though probably a native
of the region of Murcia, it is clear that he lived for a time in North Africa.
One of his preserved works (al‐Zīj al‐qawīm)
indicates that Ibn al‐Raqqām lived in Tunis, since a number of
tables are calculated for the coordinates of this city. That he also lived
in Bijāya (Bejaïa, in Algeria) is confirmed by the existence of many
astronomical tables computed for the latitude of this city in another of his
extant works (al‐Zīj al‐shāmil). At the invitation
of the second king of the Naṣrid
dynasty, Muḥammad II
(1273–1302), Ibn al‐Raqqām left Bijāya for Granada, where
he lived until his death. Ibn al‐Raqqām taught medicine and jurisprudence
in addition to other subjects. He had two known students: Abū Zakariyyāʾ
ibn Hudhayl (died: 1352), who studied mathematics, geometry, algebra, and
astronomy, and Naṣr,
another ruler of the Naṣrid dynasty (reigned: 1309–1314), who studied the composition
of almanacs and the construction of astronomical instruments.
Ibn
al‐Raqqām wrote a number of astronomical works, of which three
are extant. Two of these, are zījes (astronomical handbooks with
tables), al‐Zīj al‐shāmil fī tahdhīb al‐kāmil,
and al‐Zīj al‐qawīm fī funūn al‐taʿdīl
wa‐ʾl‐taqwīm. Al‐Zīj al‐shāmil
was composed in 1280/1281 in Tunis. According to the introduction, his aim
was to make appropriate improvements to Ibn
al‐Hāʾim's
al‐Zīj al‐kāmil. These included condensing the
explanations of this book, adding tables missing in the original, and revising
parameters in order to reach a better agreement between computation and observation.
One of the modifications made by Ibn al‐Raqqām in the explanations,
or canons, consisted of copying the words of Ibn al‐Hāʾim
without his careful geometrical demonstrations. The additional tables added
by Ibn al‐Raqqām are, in general, those of Ibn
Isḥāq al‐Tūnisī.
Ibn al‐Raqqām's zīj thus represents one of three known
editions of Ibn Isḥāq's
work produced at approximately the same time, the other two being the zīj
of Ibn al‐Bannāʾ
and an anonymous recension (written circa 1266–1281) preserved in Hyderabad.
Al‐Zīj al‐qawīm seems to be a simplified version
of al‐Zīj al‐shāmil, with a simplified set of
canons and the adaptation of some tables to the geographical coordinates of
Granada. On the whole, both zījes are similar in format and share
several numerical tables; however, there are differences since some similar
tables in each zīj have been formulated for a specific location.
For example, the tables in al‐Zīj al‐shāmil for
computing daylight lengths and unequal hours are calculated for a stated latitude
of 36°, which applies to Bijāya, while in al‐Zīj al‐qawīm
they are for 36° 37′,
the latitude of Tunis. Moreover, the latter zīj has a table for
lunar visibility calculated for the latitude of Granada, given as 37° 10′, a different figure from
the usual one for Granada in medieval times. This indicates that Ibn al‐Raqqām
reworked al‐Zīj al‐qawīm after his arrival in
Granada and that he must have made a very precise determination of the latitude
of this city, for the value he uses is exactly the modern one.
The other
preserved astronomical work of Ibn al‐Raqqām, his Risāla
fī ʿilm
al‐ẓilāl, represents the only
complete Arabic treatise on gnomonics of Andalusian origin. The work, organized
into 44 chapters, is devoted to the construction of several kinds of sundials
and discusses the mathematical and astronomical principles relevant to gnomonics,
such as the determination of hour lines or the curves of the lines for the
midday (ẓuhr) and afternoon (ʿaṣr) prayers. Ibn al‐Raqqām's
presentation is well organized, graphic, and descriptive; the work also demonstrates
his ability to use the analemma, a graphical technique not previously known
in Andalusian gnomonics.
Ibn
al‐Khaṭīb
refers to another astronomical work by Ibn al‐Raqqām, which may
have been a revision of al‐Manāj fī ruʾyāt al‐ahilla
(on lunar crescent visibility) of Ibn al‐Bannāʾ. Nonastronomical
works by Ibn al‐Raqqām mentioned by Ibn al‐Khaṭīb include a work written
in the style of Ibn Sīnā's
encyclopedic Kitāb al‐Shifāʾ, the Abkār
al‐afkār fī al‐uṣūl (on jurisprudence),
a summary of the Kitāb al‐Ḥayawān wa‐ʾl‐khawāṣṣ (probably a treatise
on medical cures using parts of the body of animals).
Selected References
Abdulrahman, Muhammad
(1996). “Ḥisāb
aṭwāl
al‐kawākib fī
al‐Zīj al‐shāmil
fī tahdhīb al‐kāmil
li‐Ibn al‐Raqqām”
(in Arabic). Ph.D. diss., University
of Barcelona.
Carandell, Juan
(1984). “An Analemma for the Determination
of the Azimuth of the Qibla in the Risāla
fī ʿilm al‐ẓilāl
of Ibn al‐Raqqām.”
Zeitschrift für
Geschichte der Arabisch‐Islamischen Wissenschaften 1: 61–72.
——— (1984).
“Trazado de las curvas de oración en los cuadrantes horizontales en la Risāla
fī
ʿilm al‐ẓilāl de Ibn al‐Raqqām.” Dynamis 4: 23–32.
——— (1988). Risāla fī ʿilm al‐ẓilāl
de Muḥammad Ibn al‐Raqqām al‐Andalusī.
Barcelona: Instituto “Millás Vallicrosa” de Historia
de la Ciencia árabe.
Ibn al‐Khaṭīb.
Al‐Iḥāṭa fi akhbār
Garnāṭa,
edited by Muḥammad ʿAbd, Allāh
ʿInān. Vol. 1, (1973); Vol. 2 (1974); Vol. 3 (1976):
69–70, 334; Vol. 4 (1978): 391. Cairo.
Kennedy, E. S. (1977). “The Astronomical
Tables of Ibn al‐Raqqām a Scientist of Granada.” Zeitschrift
für Geschichte der Arabisch‐Islamischen
Wissenschaften 11: 35–72.
Mestres, Angel
(1996). “Maghribī Astronomy in the 13th Century:
A Description of Manuscript Hyderabad Andra Pradesh
State Library 298.” In From Baghdad to Barcelona: Studies in the Islamic
Exact Sciences in Honour of Prof. Juan Vernet,
edited by Josep Casulleras
and Julio Samsó, vol. 1, pp. 383–443. Barcelona: Instituto “Millás Valicrosa” de Historia de
la Ciencia árabe.
Puig, Roser
(1983). “Dos notas sobre ciencia hispano‐árabe a finales del siglo XIII
en la Ihāta de Ibn al‐Jatīb.” Al‐Qantara 4: 433–440.
——— (1984).
“Ciencia y técnica en la Iḥāṭa
de Ibn al‐Jaṭīb.
Siglos XIII y XIV.” Dynamis 4: 65–79.
Vernet, Juan
(1980). “La supervivencia de la astronomía de Ibn al‐Bannāʾ.”
Al‐Qantara 1: 447–451.