Banū Mūsā

This article is about the 9th century Baghdad scholars. For the Iberian dynasty sometimes called the Banū Mūsā, see Banu Qasi.

Drawing of Self trimming lamp in Ahmad ibn Mūsā ibn Shākir's treatise on mechanical devices. The manuscript was written in Arabic.

The Banū Mūsā brothers ("Sons of Moses"), namely Abū Jaʿfar Muḥammad ibn Mūsā ibn Shākir (before 803 – 873), Abū al‐Qāsim Aḥmad ibn Mūsā ibn Shākir (803 – 873) and Al-Ḥasan ibn Mūsā ibn Shākir (810 – 873), were three 9th-century Persian scholars of Baghdad who are known for their Book of Ingenious Devices on automata (automatic machines) and mechanical devices. Another important work of theirs is the Book on the Measurement of Plane and Spherical Figures, a foundational work on geometry that was frequently quoted by both Islamic and European mathematicians.^[1]

The Banu Musa also worked in astronomical observations established in Baghdad by the Abbasid Caliph al-Ma'mun. They also participated in an 9th-century expedition to make geodesic measurements to determine the length of a degree.^[1]

Early life

The Banu Musa were sons of Mūsā ibn Shākir, who had been a highwayman and later an astrologer and astronomer to the Caliph al-Maʾmūn. After his death, his young sons were looked after by the court of al-Maʾmūn.^[2]

The brothers were given access to the famous House of Wisdom library and translation center in Baghdad. They participated in the efforts to translate ancient Greek works into Arabic by sending for Greek texts from the Byzantines, paying large sums for their translation, and learning Greek themselves.^[2] On such trips, Abu Ja'far met and recruited the famous mathematician and translator Thabit ibn Qurra. At some point Hunayn Ibn Ishaq was also part of their team.^[1]

Works

The Banu Musa wrote almost 20 books many of which are now lost.^[1]

Automata

Most notable among their achievements is their work in the field of automation, which they utilized in toys and other entertaining creations. They have shown important advances over those of their Greek predecessors.^[1] Their Book of Ingenious Devices describes 100 such inventions; the ones which have been reconstructed work as designed. While designed primarily for amusement purposes, they employ innovative engineering technologies such as one-way and two-way valves able to open and close by themselves, mechanical memories, devices to respond to feedback, and delays. Most of these devices were operated by water pressure.^[2]

Astronomy

• On the Visibility of the Crescent, by Muhammad.

• Book on the Beginning of the World, by Muhammad.

• Book on the Motion of Celestial Spheres (Kitāb Ḥarakāt al‐aflāk), by Muhammad.

• Book of Astronomy (Kitāb al‐Hayʾa), by Muhammad.

• Book on the First Motion of the Celestial Sphere (Kitāb Ḥarakāt al‐falak al‐ūlā), containing a critique of the Ptolemaic system. Muhammad in this book denied the existence of the Ptolemaic 9th sphere which Ptolemy thought was responsible for the motion.^[1]

• A book of zij, by Ahmad

• Another book of zij, listed under the Banu Musa, mentioned by Ibn Yunus.^[1]

• A translation of a Chinese work called A Book of Degrees on the Nature of Zodiacal Signs.

• Book on The Construction of the Astrolabe, quoted by al-Biruni.^[1]

• Book on the Solar Year, was traditionally attributed to Thabit ibn Qurra, but recent research has shown that it was actually by the Bani Musa.^[1]

Mathematics

• Book on the Measurement of Plane and Spherical Figures, later edited by Naṣīr al‐Dīn al‐Ṭūsī in the 13th century. A Latin translation by Gerard of Cremona appeared the 12th century under the titles Liber trium fratrum de geometria and Verba filiorum Moysi filii Sekir. This treatise on geometry was used extensively in in the Middle Ages, quoted by authors such as Thābit ibn Qurra, Ibn al‐Haytham, Leonardo Fibonacci, Jordanus de Nemore, and Roger Bacon.^[1]

• Book on the Mathematical Proof by Geometry That There Is Not a Ninth Sphere Outside the Sphere of the Fixed Stars, by Ahmad.

• A treatise containing a discussion between Ahmad and Sanad ibn ʿAli.

• Conic Sections of Apollonius of Perga

• Book on a Geometric Proposition Proved by Galen

• Reasoning on the Trisection of an Angle, by Aḥmad,

• Book on an Oblong Round Figure, which contains a description of procedure used to draw an ellipse using a string, now called the gardener's construction.^[1]

See also

• Their book, Book of Ingenious Devices.
• Nuʿaym ibn Muḥammad ibn Mūsā, the son of Abu Ja'far Muhammad, wrote a mathematical treatise.
• Inventions in the Muslim world
• Islamic Golden Age
• Islamic science

Notes

1. ^ ^{a b c d e f g h i j k} Casulleras 2007.
2. ^ ^{a b c} Masood, Ehsad (2009). Science and Islam A History. Icon Books Ltd. pp. 161–163. 

References

• Casulleras, Josep (2007). "Banū Mūsā". In Thomas Hockey et al. The Biographical Encyclopedia of Astronomers. New York: Springer. pp. 92–4. ISBN 9780387310220. http://islamsci.mcgill.ca/RASI/BEA/Banu_Musa_BEA.htm.  (PDF version)
• Masood, Ehsad (2009). Science and Islam A History. Icon Books Ltd. pp. 161–163. 

Further reading

• Rashed, Roshdi (1996). Les Mathématiques Infinitésimales du IXe au XIe Siècle 1: Fondateurs et commentateurs: Banū Mūsā, Ibn Qurra, Ibn Sīnān, al-Khāzin, al-Qūhī, Ibn al-Samḥ, Ibn Hūd. London  Reviews: Seyyed Hossein Nasr (1998) in Isis 89 (1) pp. 112–113; Charles Burnett (1998) in Bulletin of the School of Oriental and African Studies, University of London 61 (2) p. 406.
• D El-Dabbah, The geometrical treatise of the ninth-century Baghdad mathematicians Banu Musa (Russian), in History Methodology Natur. Sci., No. V, Math. Izdat. (Moscow, 1966), pp. 131–139.
• Ramon Guardans, A Brief Note on the anwā' Texts of the Late Tenth Century, in: Variantology 4. On Deep Time Relations of Arts, Sciences and Technologies In the Arabic-Islamic World and Beyond, ed. by Siegfried Zielinski and Eckhard Fürlus in cooperation with Daniel Irrgang and Franziska Latell (Cologne: Verlag der Buchhandlung Walther König, 2010), pp. 177–193. [1]
• Claus-Peter Haase, Modest Variations — Theoretical Tradition and Practical Innovation in the Mechanical Arts from Antiquity to the Arab Middle Ages, in: Variantology 4. On Deep Time Relations of Arts, Sciences and Technologies In the Arabic-Islamic World and Beyond, ed. by Siegfried Zielinski and Eckhard Fürlus in cooperation with Daniel Irrgang and Franziska Latell (Cologne: Verlag der Buchhandlung Walther König, 2010), pp. 195–213. [2]

External links

• al-Darrbagh, J. (2008) [1970–80]. "Banū Mūsā". Complete Dictionary of Scientific Biography. Encyclopedia.com. http://www.encyclopedia.com/doc/1G2-2830900258.html. 
• O'Connor, John J.; Robertson, Edmund F., "Banu Musa brothers", MacTutor History of Mathematics archive, University of St Andrews, http://www-history.mcs.st-andrews.ac.uk/Biographies/Banu_Musa.html .
• O'Connor, John J.; Robertson, Edmund F., "Ahmad Banu Musa", MacTutor History of Mathematics archive, University of St Andrews, http://www-history.mcs.st-andrews.ac.uk/Biographies/Banu_Musa_Ahmad.html .
• O'Connor, John J.; Robertson, Edmund F., "al-Hasan Banu Musa", MacTutor History of Mathematics archive, University of St Andrews, http://www-history.mcs.st-andrews.ac.uk/Biographies/Banu_Musa_al-Hasan.html .

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Name	Musa, Banu
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Date of death	873
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