The Dissemination of Arab Astronomy East and West. The Role of Instrumentation

Scientific Essay, 2016

18 Pages



1. The Phase of translation and its effects

2. The need to instrumentation
2.1. Instrumentation of astronomy
2.2. On instruments and their makers
2.3 Technical works on how to make one’s own instrument

3. The Role of Instrumentation in Dissemination
3.1. Popularizing astronomy by treatises
3.2. Popularizing astronomy by instruments

Temporary Conclusions

Works Cited.

Reconstructing the history of Arab astronomy will only be possible by the study and analysis of both its texts – old and new – and its different instruments, a systematic process that will certainly shed more light on the different mechanisms and phases of the continuous evolution of this science. The translation of Greek astronomy works into Arabic in the 8th and 9th centuries and the different implications that it represents are issues that need further investigation, especially as regards the concept of astronomy dissemination among common people. The aim of this paper is to bring into prominence the effects of astronomy popularization that came as a consequence of the movement of translation and of the ensuing wave of instrumentation andcommentating works.

1. The Phase of translation and its effects

The movement of translation that took place in Baghdad during the 8th and 9th centuriescame within the intellectual and cultural flourishing in the Abbasid era and favoured the emergence of a real ‘melting pot’ of translators and scholars coming from different cultures, religions, and ethnicities. It is this “international” aspect in particular that Rushdī Rāshid stressed on when he was considering the sum of works that have been recently made on the history of Arab science; such works, according to him, allow to single out a characteristics of this science that “has been so far left in the dark”and whichis according to him, the global aspect of Arab science and – contrarily to the Greek science – its ability to “develop around the Mediterranean Sea, not only as a geographical space but also as a point of communication and exchange between all the civilizations at the centre of the Old World and around it as well” (Rāshid, 2005, p. 15). These international encounters were not limited to a single geographical space, which could be Damascus or Baghdad, but it operated in an interactive way between nations, thus paving the way for transnational interactions, especially in the very practical field of astronomy. The proliferation of translations, new treatises, and popularizing works on astronomy broadened the scope of its users and pulverised it into a wide convex of disciplines according to the need or taste of each user. Hence, the need to narrow the gap between erudite translators and ‘specialists’, on one side, and more ordinary or users and ‘amateurs’, on the other side.

2. The need to instrumentation

The widespread use and study of astronomy works and instruments generated new disciplines within the hitherto unified science of astronomy, which is a neat sign of the flourishing of scientific development. Most of Arabic bio-bibliographical works concerned with the classification of sciences divided astronomy into tens of new sciences resulting from its bifurcations and branching due to new findings. In this juncture, the process of instrumentation of astronomy had become a practical need and required new treatises specially dedicated to its individual parts to the extent that the making of each astronomical instrument ceased to be an art and became an independent science in itself. Among the sciences that Hajji Khalifa enumerated as being related to astronomy, he itemized the ‘science of making the astrolabe, the science of using the astrolabe, the science of making the quadrant and the almicantarat, the science of using the quadrant, and the science of clocks making.’ (1992, Vol. 1, p. 16).

The need to use different kinds of instruments at this phase was also felt for many reasons. In his attempt to justify this need, Taki Ad-Din Arrasid mentioned the difference of diurnal revolutions from one place to another (Khalifa Vol. 1, 2005, p. 146). The other need was the will to perfection and easiness, as this was well expressed by Ibn Ashātir in his critical assessment of all the instruments made before him. He found that ‘such instruments are not all useful for all latitudes; that some of them are difficult to use because of their mechanical complexity; that some of them offer only a limited number of uses; and that some of them give solutions by a lengthy way that goes beyond the limit’ (Khalifa Vol. , p. 147). So he decided to make an instrument that would do all business for all horizons with easiness and a clear proof, which he calledthe ‘complete quadrant.’

2.1. Instrumentation of astronomy

At the larger scale, it goes without saying that that al-Mamoun was the first who commanded for the use of instruments in astronomic observation. He constructed to this effect both the observatory on Qassiūn Mountain in Damascus and the one in Shamāssiyeh in Baghdad. During his Caliphate and after his death several observatories were erected in different parts of the Islamic world (Kahāla, 1972 , p. 170). In his global assessment of Arabic astronomy at this genetic phase, Regis Morelon (2005) draws the attention to the fact that the research activities on astronomy began really and effectively when a comprehensive program of continuous observation had been launched then developed during the Caliphate of Al-Ma’mun just before 830 CE. It was clear since then that astronomy sciences were stressing on “the precision of instruments and on the necessity to go through continuous and repeated observations” (p. 82). But at a more individual level, the process of instrumentation itself was of necessity triggered first by the desire to illustrate astronomy, both as a set of notions and as a craft, and to bring it closer to the understanding and observation of everyone. This is, for instance, how the spherical or convex astrolabe of Ptolemaic was rendered plane and made easier to take from one place to another; that is, it was made into a more handy and mobile instrument. On this point, Sédillot (1844) assumed that Arabs had come to a very high degree of perfection in the construction of this instrument to the extent that many of their astronomers have received the honorary nickname of Asterlabi [astrolabian] (p. 153). Among the many cases in point, he mentions in this regard the Safeeha of horizons (&الصفيحة الآفاقية&) and the board that Arabs call alancabuth or the Spider, because it is updated, and can be applied to all heights of the pole (pp. 162-163). As for the instruments that Sédillot considered as belonging specifically to the Arabs, “the most curious is unquestionably the sextant, and the description that we will do of it will settle an important point in the history of science” (p. 199).

The popularization of astronomy among Arabs in that period was mainly made easier by the introduction of new and easy-to-use instruments. When describing the way to make the square quadrant to be used for the different observations and measurements, (Al-Battani, 1899) gave a detailed account on its dimensions and even on the material of which it should be made, whether of copper, stone, or wood (pp. 214-215). He also suggested unprecedented improvements to such instruments. As a case in point, in his detailed account on how to locate the place of the crescent in a particular horizon, he suggested the use of a ‘straight ruler or a hollow tube’ to be adjusted to the astrolabe (p. 137). Al-Battani’s ‘hollow tube’, six times mentioned as an instrumental device (pp. 137-138), was unprecedented in astronomical works written before him, and we can say that the device became an inescapable paradigm to be improved and used in all the subsequent astronomical observations, from Ibn Al-Haitham, through Galileo, to the modern designers of Hubble and other tube–telescopes. Closer to this mood of perfection is the improvement of the gnomon; Sédillot (1844) left no doubt and even demonstrated that it was Arabs who first used the gnomon with a hole (pp. 12fn; 37).

The next step in the perfection of such instruments was the tendency to increase the size of instruments for more mathematical precision and for calculating and observing phenomena that are hard to grasp with the naked eye (Marhaba, 1998, pp. 415-416). This magnifying and enlarging process reached some unprecedented dimensions to the extent that, in some case, the diameter of some armillary spheres measured more than 5 meters. According to Sédillot (1844), Ibn Yunus informed us that the Arabs loved the large instruments and Al-Bîrunî was using a quadrant of fifteen cubits, and we know what Gravius reported on Ulugh-Beg (p. 45). When Ibn Qarāqah was blamed for the excessive greatness of such armillaries, he said: “If I could make an armillary whose foot is on the Pyramids and the other foot on Attanour Mosque across the Nile, I would have done it, because the bigger the instrument, the truer is the calculation; what is this beside the heavenly world?” (Ahmed, 1991, p. 74).

When describing Arab astronomical instruments, Sigrid Hunke (1963), praised more particularly the huge industrial infrastructure that is revealed in the background of this arsenal:

"Arabs never ceased to expand the rings constituting the armillary sphere, so called by Ptolemy, to refine their scale and to make their measures more precise. Their copper rings reached a diameter of three meters and a half if not more. We come to wonder how they succeeded in making such gigantic rings, while on the precision of their execution everything else depended. They had undoubtedly possessed lathes to cut circles in the spheres." (p. 88).

According to David King (2005), Ibn Shātir the astronomer, who was also the head of time-keepers at the Umawiyyeen Mosque in Damascus in the middle of the 14th c., made in 1371/1372 a wonderful horizontal sundial with the size of about 2 meters over 1 meter (p. 214). Roger Morelon ( 2005 ), on his part, draws the attention to “One other instrument of great size, cut into a permanent base of masonry,” which is described by Ibn Sina (AH 370–428 (AD 980–1037)) in his treatise Maqala fi al-ālāt al-rasdiyya. On the top of a circular wall about 7 m in diameter laid a completely horizontal graduated circle. At the centre of the ) circle was a pillar bearing a double, vertically jointed rule, which could pivot horizontally around the centre (pp. 11-12). This construction was therefore based on a similar principle to that of the ‘observation tube’ described by Al-Battānī. About two centuries later, at Maragha, Ibn Sina’s instrument was further developed by the addition of a second set of jointed rules – or by an analogous arrangement of two vertical sighting devices pivoting independently around the centre of the large stone circle – enabling simultaneous measurement of the height and azimuth of two celestial objects. The instrument described by Ibn Sina – and probably invented by him – is of particular interest because its new sighting system was much more precise than that of earlier instruments, giving independent readings of degrees and minutes” (Morelon,&2005& , p. 12). This allowed everyman to seize the cosmos and become either a professional astronomer, being then endowed with the adequate scholarship in the field, or a user, being then equipped with the essential culture and the necessary techniques and instruments to measure time and to define geographical directions.

2.2. On instruments and their makers

The detailed records on how and where astronomy instruments were technically made and how the system of this craftsmanship was functioning in the early Arabic-Islamic context did not get due interest in the books of astronomy history. Apart from the essential bio-bibliographical sources, which give summative information, the other astronomy books, most of which still in manuscript form, give rather ample information on how to conceive and mathematically design such instruments, how to make them according to such designs, and how to use them. To get such information, it seems that historians of this science have to resort to the quantitative and qualitative analysis of the existing instruments in the different museums of the world and apply a rather deductive method to fill in the gaps left by the lack of written records. In this section, we will try to profit from both methods and show how the process of making instruments was itself done with the intention to popularize this science among the largest sections of users both as ‘professionals’ and as ‘amateurs’.

To begin with historical sources, Ibn Nadīm stated that the first one to have made astrolabes [among the Greeks] was Ptolemy and that they had been probably made before him, ‘but this cannot be known for sure.’ As for the Abbasid state, Ibn Nadīm assumed that the construction of astrolabes increased since the days of Al-Mamūn ‘to the present time’ – which is the end of the 10th c. When Al-Mamūn wanted to proceed in observation, he ordered Almurūrozy to construct for him the armillary sphere; this craftsman also made the astrolabe (p. 342). However, it is Al-Fazārī who is famous for having been the first to make an astrolabe in Islam. After him, many astronomers made such instruments to the extent that they became highly specialized makers of instruments and succeeded to become masters of the art who trained their own apprentices. More and more treatises succeeded to the extent that we can assign to each Arab astronomer at least one or two books on this instrument. The outcome was a large amount of treatises on the astrolabe, mostly in the form of manuscripts scattered in national and international libraries. These treatises can be divided into two categories: the treatises of how to design a personal astrolabe, on the one hand, and treatises on how to use it, on the other.

As cases in point, Reda Kahala (1972) mentioned Alkūhi, a scientist of the 10th c. AD, who “was an authority in astronomy, so steeped in it and was famous for constructing observation instruments and making accurate observations” and As-Saghāni (d. 989 in Baghdad), who “was known for making astrolabes and for his mastery in constructing observation instruments too” (p. 183). This system of apprenticeship can be inferred from Ibn Nadīm (1971)’s lists of astronomy craftsmen. One of his particular lists of the names of astronomy instruments makers offers invaluable information on the global atmosphere and the apprenticeship mechanism of this system:

Ibn Khalaf Almurūruzy; Al-Fazāri; Ali Ibn Issa, Almurūrozy’s apprentice; Khafif, Ali Ibn Issa’s apprentice; Ahmed Ibn Khalaf, Ali Ibn Issa’s apprentice; Mohamed Ibn Khalaf, also Ali Ibn Issa’s apprentice; Ahmed Ibn Ishāq al-Harrāni; Arrabī’ Ibn Firās al-Harrānī; Bathyllus, Khafīf’s apprentice; Ali Ibn Ahmed al-Muhandis (the Engineer), Khafīf’s apprentice. Mohammed Ibn Shaddād al-Baladī, (Bathyllus’s apprentice); Ali Ibn Sard al-Harrāni (Bathyllus’s apprentice); Shujāa Ibn… Bathyllus’s apprentice, was with Saifu ad-Dawlah; Ibn Salām, Bathyllus’s apprentice; Al-Ijlī the Astrolabian, Bathyllus’s apprentice; Al-Ijliyah daughter of Al-Ijlī, Bathyllus’s apprentice; she was with Saifu ad-Dawlah&.&(Ibn Nadim, pp. 342-343)

This is a very important list as it allows us to have an idea on how the art of making instruments was transmitted. At least three points can be inferred from this list:

1. that there was an undeniable system of apprenticeship exactly like the one that was undertaken in the transmitting of other sciences in Islamic scholarship, the ones known as Ulum al-Ala (&علوم الآلة&). The master of the art trains a number of apprentices who become, on their turn, masters and so on, so that we have, at least, five classes of masters-apprentices in this list, which we illustrate in the following diagram:

illustration not visible in this excerpt

The existence of this system of apprenticeship and transfer of the craft is also confirmed by Al-Qiftī (2005), who states that, among the deeds of Abu Hāmed Ahmed Ibn Muhammad Assaghanī Al-Astorlābī (d. 989 AD), was ‘a number of his apprentices [who] excelled in astrolabes and observation instruments and they were proud of it.’ (p. 65)

2. that there was a system of scientific patronage, which is exemplified here by the recurrent allusion to Saifu ad-Dawlah (916-967), best known for encouraging scientific, intellectual and literary figures;

3. that even female apprentices were makers of astronomical instruments, like Al-Ijliyyah, daughter of al-Ijlī; and in this context, an apprentice is self-evidently a future master of the art.

Worth noticing, in this regard, is that Sedillot, in his Mémoire, describes an astrolabe that was made most probably by this very Ahmed Ibn Khalaf mentioned by Ibn Nadim in this list. His words leave no doubt:

We were fortunate enough to get us two former Arab astrolabes having a certain date; one was made around the year 905 AD, and it is now in the Royal Library... We read [on one of the two dials] between the 20th and the 55th degrees the following words: ‘Made by Ahmed bin Khalaf’, and below the suspension ring: ‘For Djafar son of Moktafī Billāh’.” (pp. 172-173)


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The Dissemination of Arab Astronomy East and West. The Role of Instrumentation
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Khalid Chaouch (Author), 2016, The Dissemination of Arab Astronomy East and West. The Role of Instrumentation, Munich, GRIN Verlag,


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