Al-Fargh?n?, Abu’l-‘Abb?s A?mad Ibn Mu?ammad Ibn Kath?r

(b. Fargh?na, Transoxania; d. Egypt, after 861)

astronomy.

Al-Fargh?n? was one of the astronomer-astrologers employed by the Abbasid caliph al-Ma‘m?m, who reigned in Baghdad from 813 to 833. His name sometimes occurs in the Arabic sources as Mu?ammad ibn Kath?r, sometimes as A?mad ibn Mu?ammad ibn Kath?r, and it was probably this variation (in addition to variations of the title of his best-known book—see below) that led Ibn al-Qif? to assume the existence of two Fargh?n?s, a father and a son. But this assumption has now been generally dismissed as very likely no more than a misunderstanding.¹

A1-Fargh?n?’s activities extended to engineering, and it is in connection with his efforts as an engineer that we have some biographical information about him. According to Ibn Taghr?bird?, he supervised the construction of the Great Nilometer (al-miqy?s alkab?r), also known as the New Nilometer (al-miqy?s al-jad?d), also known as the New Nilometer (al-miqy?s al–jad?d), at al-Fus??? (Old Cairo). It was completed in 861, the year in which the caliph al-Mutawakkil, who ordered the construction, died. (The Wafay?t al-a ‘y?n of Ibn Khallik?n reports the event but, in the Cairo edition, gives the name of the engineer as A?mad ibn Mu?ammad al-Qars?n?, the last word being no doubt a corruption of “al-Fargh?n?”—see bibliography.) But engineering was not al-Fargh?n?s forte, as appears from the following story, which Ibn Ab? U?aybi‘a transcribed from the Kit?b al-Muk?fa?a of A?mad ibn Y?suf,² who heard it from Ab? K?mil.

Al-Mutawakkil had charged the two sons of M?s? ibn Sh?kir, Mu?ammad and A?mad, with supervising the digging of a canal named al-Ja‘far?. They delegated the work to “A?mad ibn Kath?r al-Fargh?n? who constructed the New Nilometer,” thus deliberately ignoring a better engineer, Sanad ibn ‘Al?, whom, out of professional jealousy, they had caused to be sent to Baghdad, away from al-Mutawakkil’s court in S?marr?. (The caliphal capital had been transferred from Baghdad to S?marr? by al-Mu‘ta?im in 836.) The canal was to run through the new city, al-Ja‘fariyya, which al-Mutawakkil had built near s?marr? on the Tigris and named after himself. Al-Fargh?n? committed a grave error, making the beginning of the canal deeper than the rest, so that not enough water would run through the length of the canal except when the Tigris was high. News of this angered the caliph, and the two brothers were saved from severe punishment only by the gracious willingness of Sanad ibn ‘Al? to vouch for the correctness of al-Fargh?n?’s calculations, thus risking his own welfare and possibly his life. As had been correctly predicted by astrologers, however, al-Mutawakkil was murdered, shortly before the error became apparent.³ The explanation given for al-Fargh?n?’ mistake is that being a theoretician rather than a practical engineer, he never successfully completed a construction (wa-k?nat ma‘rifatuhu awf? min tawf?qihi li-annahu m? tamma lahu ‘amalun qua??u). Al-Ya‘q?b? (d. 897) gives a more charitable reason for al-Fargh?n?’s failure: the stony ground chosen for al-Ja‘fariyya, a place called al-M???za, was simply too hard to dig. He does not mention al-Fargh?n? by name, but says that work on the canal was entrusted to “Mu?ammad ibn M?s? al-Munajjim and those geometers who associated themselves with him” (Kit?b al-buld?n, p. 267).

The Fihrist of Ibn al-Nad?m, written in 987, ascribes only two works to al-Fargh?n?: (1) “The Book of [the thirty?] Chapters, a summary of the Almagest” (Kit?b al-Fu??l, ikhtiy?r⁴ al-Majis??), and (2) a “Book on the Construction of Sundials” (Kit?b ‘Amal al-rukh?m?t). Ibn al-Quift? (d. 1248) reproduces the same list under Mu?ammad ibn Kath?r (the name that occurs in the Fihrist) but splits the first title into two: Kit?b al-Fus??l and Kit?b Ikhti??r [sic] al-Majis??. To A?mad ibn Mu?ammad ibn Kath?r he attributes one work, entitled Al-Madkhal il? ‘ilm hay al-afl?k wa-?arak?t al-nuj?m (“Introduction to the Science of the Structure of the Spheres and of the Movements of the Stars”) which he describes as consisting of thirty chapters (singular,b?b) presenting a summary (jaw?mi‘) of the book by Ptolemy. This is the only title assigned to al-Fargh?n? by Ibn ??‘id (d. 1244) and Bar-Hebraeus (d. 1286). As has been noted, the two Fargh?n?s are in fact one; and the same work that Ibn al-Qift? mistakenly believed to be two has in fact been known by a variety of titles: Jaw?mi‘ilm al-n?j?m wa ’l-?ark?t al-sam?wiyya, U??l ‘ilm al-n?j?m, Kit?b al thal?th?n, Ilal al-afl?k, and so on. This takes us back to the list in Ibn al-Nad?m; but other works must be added to it, notably two(?) treatises on the astrolabe that have come down to us and a commentary on the astronomical tables of al-Khw?rizm?.

The Jaw?m?‘ or the Elements, as we shall call it here, was al-Fargh?n?’ best-known and most influential work. He wrote it after the death of al-Ma‘m?n in 833 but before 857. Abu’l-?aqr al-Qab?s? (d967) wrote a commentary on it which is preserved in the Istanbul manuscript, Aya Sofya 4832, fols. 97v–114v. Two Latin translations of the Elements were made in the twelfth century, one by John of Spain (John of Seville) in 1135⁵ and the other by Gerard of Cremona before 1175. Printed editions of the first translation appeared in 1493, 1537, and 1546. (Gerard’s translation was not published until 1910.) Jacob Anatoli made a Hebrew translation of the book that served as a basis for a third Latin version, which appeared in 1590, and Jacob Golius published a new Latin text together with the Arabic original in 1669. (For particulars of these editions, see bibliography.) The influence of the Elements on medieval Europe is clearly attested by the existence of numerous Latin manuscripts in European libraries. References to it in medieval writers are many, and there is no doubt that it was greatly responsible for spreading knowledge of Ptolemaic astronomy, at least until this role was taken over by Sacrobosco’s Sphere. But even then, the Elements of al-Frargh?n? continued to be used, and Sacrobosco’s Sphere was clearly indebted to it. It was from the Elements (in Gerard’s translation) that Dante derived the astronomical knowledge displayed in the Vita nuova and in the Convivio. The following is a summary of the contents of the thirty chapters constituting the Elements

Chapter 1, to which nothing corresponds in the Almagest, describes the years of the Arabs, the Syrians, the Romans, the Persians, and the Egyptians, giving the names of their months and days and the differences between their calendars. Chapters 2–5 expound the basic concepts of Almagest I.2–8: sphericity of the heaven and of the earth, the central position of the earth, and the two primary movements of the heavens. In chapter 5 al-Fargh?n? gives the Ptolemaic value for the inclination of the ecliptic as 23° 51?, and reports the value determined at the time of al-Ma‘mun as 23° 35?.⁶ (In one of his treatises on the astrolabe he states a different value observed at a later date.) Chapters 6–9 give a description of the inhabited quarter and list the seven climes and the names of well-known lands and cities. In chapter 8 al-Fargh?n? gives the Ma‘m?nic measurements of the circumference and the diameter of the earth: 20,400 miles and approximately 6,500 miles, respectively. Chapters 10–11 discuss ascensions of the signs of the zodiac in the direct spheres, al-afl?k al-mustaq?ma (ie., horizons of the equator), and oblique spheres, al-afl?k al-m??ila (i.e., horizons of the climes), and equal and unequal (zam?niyya, temporal) hours

There follow descriptions of the spheres of each of the planets and their distances from the earth (chapter 12); movement of the sun, moon, and fixed stars in longitude (chapter 13); movements of the five planets in longitude (chapter 14); retrograde motions of the wandering planets (chapter 15); magnitudes of eccentricities and of the epicycles (chapter 16); and revolutions of the planets in their orbs (chapter 17). The assertion of chapters 13 and 14 is that the slow eastward motion of the sphere of the fixed stars about the poles of the ecliptic through one degree every 100 years (the Ptolemaic value) is shared by the spheres (the apogees) of the sun, as well as of those of the moon and the five planets.

Chapter 16 concerns movements of the moon and of the planets in latitude; chapter 19, the order of the fixed stars in respect of magnitude and the positions of the most remarkable among them (al-Fargh?n? counts fifteen); chapter 20, lunar mansions; chapter 21, the distances of the planets from the earth (Ptolemy had stated only the distances of the sun and the moon); chapter 22, the magnitudes of the planets compared with the magnitude of the earth (“Ptolemy only showed the magnitude of the sun and of the moon, but not that of the other planets; it is, however, easy to know the latter by analogy with what he did for the sun and the moon”); chapter 23, rising and setting; chapter 24, ascension, descension, and occultation; chapter 25, phases of the moon; chapter 26, emergence of the five planets; chapter 27, parallax; chapters 28–30, solar and lunar eclipses and their intervals.

Al-Fargh?n?’s Jaw?mi‘ thus gives a comprehensive account of the elements of Ptolemaic astronomy that is entirely descriptive and nonmathematical. These features, together with the admirably clear and well-organized manner of presentation, must have been responsible for the popularity this book enjoyed. It must be noted that, as far as numerical values are concerned, the early printed editions show significant divergences. For example, Mercury’s diameter is given no fewer than four different values: 1/28, 1/20, 1/10, and 1/18 the diameter of the earth. Only one edition (Frankfurt, 1590) has the first correct value.⁷ And in Golius’ 1669 Arabic-Latin edition, which is generally superior to the earlier ones, the value of the same diameter differs in the Latin translation (where it is given as 1/18 the diameter of the earth) from that in the Arabic text (1/28 the diameter of the earth).

Al-Fargh?n?’s writings on the astrolabe survive in a number of manuscripts bearing different titles: F??an‘at al-as?url?b, al-K?mil fi ’l-as?url?b, Kit?b ‘Amal al-as?url?b. The thirteenth-century manuscript at the British Museum (Or. 5479)⁸ is a substantial work of forty-eight folios (37v-85r) that ought to be counted among the more respectable treatises devoted to this subject in Arabic. Addressed to the scholar who has reached an “intermediate stage in the knowledge of geometry and the computation of the stars” (fol. 38r), it deals at length with the mathematical theory of the astrolabe and purports to correct faulty constructions which were current at the time of its writing. It is no more rule-of-thumb manual and was in fact intended to resolve doubts and difficulties created by such manuals. In this work al-Fargh?n? states the inclination of the ecliptic to be 23°33?, “as we found by observation in our time” (fol. 46v). On page 49v “our time” is given as the year 225 of Yazdegerd, i.e., a.d. 857–858.

Al-B?r?n? in his treatise On the Calculation of Chords in Circles assigns to al-Fargh?n? a work entitled Ilal Z?j al-Khw?rizm?, in which, apparently, al-Fargh?n? gave explanations (‘ilal reasons) for al-Khw?rizm?’s computational procedures.⁹ This work has been lost. But in addition to its having been available to and made use of by al-B?r?n? in the eleventh century, it had been carefully studied by A?mad ibn al-Muthann? ibn ‘Abd al-Kar?m in the tenth. Ibn al-Muthann?, whose commentary on al-Khw?rizm?’s tables survives in Hebrew and Latin translations, tells us that he found al-Fargh?n?’s book lacking in proofs and altogether suffering from omissions and redundancies. But his remarks would suggest that his own book was either based on al-Fargh?n?’s treatise or at least took its starting point from it. The Latin translation, made by Hugo of Santalla in the second quarter of the twelfth century, was reported by C. H. Haskins but, following Suter, was wrongly identified as a commentary on al-Fargh?n? by al-B?run?.¹⁰ Two Hebrew versions of Ibn al-Muthann? have recently been published with English translation.¹¹

NOTES

1.See H. Suter’s art. on al-Fargh?n? in the 1st ed. of the Encyclopaedia of Islam and the rev. art. by J. Vernet in the 2nd ed. See also C. Nallino, “Astrologie e astronomia presso iimusulmani,” in Raccolta di scritti editi e inediti, V (Rome, 1944), 135.

2.Ibn Ab? U?aybi‘a, ?abaq?t al-a?ibb?’, p. 207, refers to Kit?b Husn al-‘uqb?, the title of a ch. in Kit?b al-Muk?fa‘a.

3. According to the same story, going back to Ab? K?mil, another victim of the intrigues of the two sons of M?s? was the philosopher al-Kind?, whom they had caused to be estranged from al-Mutawakkil and whose library they had confiscated. Sanad’s condition for getting them out of their difficulty was that the library be restored to al-Kind?.

4.Ikhtiy?r (selection) is found in G. Flügel’s ed. of the Fihrist and in the (undated) Cairo ed. But the word should no doubt be read ikhti??r (summary).

5.See F. Woepcke, “Notice sur quelques manuscrits arabes relatifs aux mathématiques...,” pp. 116–117.

6. Ibn Y?nus reports that the mission ordered by al-Ma‘m?m to prepare the so-called Mumtahan or Ma’m?z?c z?j recorded two values of the obliquity at two different places and times: 23°33?’ at Baghdad in a.h. 214 (a.d. 829–833), and 23°33?52? at Damascus in a. h. 217 (a.d. 832–833). According to the Princeton University Library MS Yahuda 666 (fol. 37v), al-Fargh?n? reported two values from the Mumta?am: one equal to the Baghdadian determination of 23°33? and the other the same as that stated in the Elemetns: 23°35?. For Ibn Y?nus, see Notices et extraits des manuscrits de la Bibliotheque Nationale..., VII (Paris, 1803), 56–57.

7.See P. J. Toynbee, “Dante’s Obligations to Alfraganus...,” p. 424, n. 1.

8. Copies of the same work are in the Berlin MSS nos. 5790, 5791, and 5792. A fourth MS at Berlin, no. 5793, fols. lr-97v, not seen by the present writer, seems to be a different work. See W. Ahlwardt, Verzeichnis der arabischen Handschriften der Königlichen Bibliothek zu Berlin, V (Berlin, 1893), 226–227.

9.See “Ris?la fi istikhr?j al-wat?r fi ’‘l-d?‘ira,” in Ras?’il al-B?run?, I (Hyderabad, 1949), pp. 128, 168.

10.See C. H. Haskins in Romanic Review, 2 (1911), esp. 7–9, and his Studies in the History of Mediaeval Science, 2nd ed. (Cambridge, Mass, 1927), p. 47, where the same mistaken identification is repeated. But see Millás Vallicrosa, Estudios sobre Azarquiel (Mardrid-Granad, 1943–1950), pp. 25–26.

11. See Bernard R. Goldstein, Ibn al-Muthann?’s Commentary on the Astronomical Tables of al-Khw?rizm? (New Haven-London, 1967). Hugo’s Latin text is edited by Eduardo Millás Venderell, S. I., in El comentario de Ibn al-Mutann?‘ a las Tablas Astronómicas de al-Jw?rizm? (Madrid-Barcelona, 1963).

BIBLIOGRAPHY

I. Original Works. The Latin trans. of the Elements by John ops Spain was first printed at Ferrara in 1493; Breuis ac perutilis compilatio Alfragani astronomorum pertissimi totum id continens quo ad rudimenta astronomica est opportunum. This was reprinted at Nuremberg in 1537 as part of Continentur in hoc libro Rudimenta astronomica Alfragani. Item Albategnius.... De motu stellarum, ex observationibus tum proprijs, tum Ptolemaei, omnia cum demonstrationibus geometricis &additionibus Ioannis de Regiomonte. Item Oratio introductoria in omnes scientias mathematicas Ioannis de Regiomonte.... Eiusdem introductio in Elementa Euclidis. Item epistola Philippi Melanthonis nuncupatoria, etc. A second reprint, giving the name of the translator for the first time in print, appeared at Paris in 1546; Alfragania astronomorum pertissimi compendium, id omne quod ad Astronomica rudimenta spectat complectens, Ioanne Hispalensi interprete, nunc primum peruetusto exemplari consulto, multis locis castigatus redditum. Francis J. Carmody’s ed., Alfragani Differentie in quibusdam collectis scientie astrorum (Berkeley, Calif., 1943), gives a critical representation of John’s version based on some of the extant MSS.

The Latin by the Heidelberg professor Jacob Christmann, published at Frankfurt in 1590, made use of John’s version as well as of a Hebrew trans. by Jacob Anatoli: Muhamedis Alfragani Arabis Chronologica et astronomica elementa, e Palatinae Bibliothecae verteribus libris versa, expleta, et scholiis expolita. Additus est Commentarius, qui rationem calendarii Romani, Aegyptiaci, Arabici, Persici, Syriaci & Hebraei explicat.... According to Woepcke (see below), p. 120, this version was reprinted in 1618.

Gerard of Cremona’s trans., made before 1175, was not printed until 1910; Alfragano (Al-Farg?n?) Il ’Libro dell’ aggregazione delle stelle’ (Dante, Convivio, II, vi–134) secondo il Codice Mediceo-Laurenziano, Pl. 29, Cod. 9 contemporaneo a Dante, introduction and notes by Romeo Campani (Citta de Castello, 1910).

An ed. of the Arabic text was prepared by Jacob Golius on the basis of a Leiden MS. It was published (Amsterdam, 1669) after Golius’ death with a Latin trans. and copious notes covering only the first nine chs. of al-Fargh?n?’s book: Muhammedis Fil. Ketiri Ferganensis, qui vulgo Alfraganus dicitur, Elementa Astronomica, Arabice & Latine. Cum notis ad res exoticas sive Orientales, quae in iis occurrunt.

Ch. 24 of the Elements, De ortu et occasu Planetarum, et de occultationibus eorum sub radiis solis, was twice printed gother with Sacrobosco’s Sphere: Sphera Ioannis de Sacro Bosco emendata, etc. (Paris, 1556), fols. 53r-54v; (Paris, 1564), fols. 58v-60r.

For the Arabic MSS of al-Fargh?n?’s works, see C. Brockelmann, Geschichte der arabischen Literatur, I, 2nd ed. (Leiden, 1943), 249–250; supp. vol. I (Leiden, 1936), 392–393. See also H. Suter, Die Mathematicker und Astronomen der Araber und ihre Werke (Leipzig, 1900), pp. 18–19.

MSS of Jacob Anatoli’s Hebrew trans, of the Elements are listed in M. Steinschneider, Die hebraeischen übersetzungen des Mittelalters (repr. Graz, 1956), pp. 554–559 (sec.343).

For Latin MSS of the Elements, see F. Woepcke, “Notice sur quelques manuscrits arabes relatifs aux mathématiques, et récemment acquis par la Bibliothèque impérale”, in Journal asiatique, 5th ser., 19 (1862), 101–127, esp. 114–120; F.J. Carmody, Arabic Astronomical and Astrological Sciences in Latin Translation, A Critical Bibliography (Berkeley-Los Angeles, 1959), pp. 113–116.

A brief but useful description of the early European eds. of the Elements is in P.J. Toynbee, “Dante’s Obligations to Alfraganus in the Vita Nuova and Convivio,” in Romania, 24 (1895), 413–432, esp. 413–417.

II Secondary Literature. Biographical and bibliographical information is in Ibn al-Nad?m, al-Fihrist, G. Flügel, ed., I (Leipzig, 1871), 279; Ibn al-Quif??, Ta‘r?kh al-?ukam?’, J. Lippert, ed. (Leipzig, 1930), pp. 78, 286; Ibn Ab? U?aybi‘a ?abag?t al-a?ibb??, A. Müller, ed., I (Cairo, 1882), 207–208; Abu ’l-Faraj ibn al-‘Ibr? (BarHebraeus), T?’rikh mukhta?ar al-duwal, A. ??lh?n?, ed. (Beirut, 1890), pp. 236–237; Ibn ??‘id al-Andalus?, ?baq?t al-umam, L. Cheikho, ed. (Beirut, 1912), pp. 54–55; Ibn Khallik?n, Wafay?t al-a‘y?n I (Cairo, 1882), 483–485—the relevant passage in the ch. on Abu ?I-Rad?d is missing from F. Wüstenfeld’s ed. of the Wafay?t, fasc. 4. (Göttingen, 1837), no. 362, p. 53, and from de Slane’s trans., IbnKhallikan’s Biographical Dictionary, II (Paris, 1843), 75; Ibn Taghr?bid?, al-N?j?m al-z?rhira, T.G.J. Juynboll and B.E. Mathes, eds., I (Leiden 1851), 742–743; A?mad ibn Y?suf, Kit?b al-Muk?fa’a, A?mad Am?n and ’Al? al-J?rim, eds. (Cairo, 1941), pp. 195–198. Gaston Wiet discusses al-Fargh?n?s construction of the “New Nilometer”, in “Une restauration du Nilomètre de l’ile de Rawda sous Mutawakkil (247/861),’ in Comptes rebdus de l’Académie des inscriptions et belles-lettres (1924), pp. 202–206. Here Wiet cites a reference in Ibn al-Zay?t’s al-Kaw?kibal-say?ra to the tomb of al-Fargh?n? in the qar?fa of Cairo, thus giving evidence that al-Ja’far? project is to be found in al-Ya‘qubi, Kit?b al-buld?n, in Bibliotheca geographorum arabicorum, M. J. De Goeje, ed., 7 (Leiden, 1892), 266–267. See also Y?q?t, Mu‘jam al-buld?n, F. Wüstenfeld ed., II (Leipzig, 1867), 86–87; III (Leipzig, 1868), 17; and IV (Leipzig, 1869), 413.

A trans. of al-Fargh?n?s intro. to his treatise on the astrolabe (Berlin MS no. 5790) is included in Eilhard Wiedemann “Einleitungen zu arabischen astronomischen Werken”, in Weltall, 20 (1919–1920), 21–26, 131–134; see also Wiedemann’s “Zirkel zur Bestimmung der Gebetszeiten”, in Beiträge zur Geschichte der Naturwissenschaften62, in Sitzungsbeichte der Physikalish-medizinischen Soziet?t in Erlangen, 52 (1922), 122–125. J. B. J. Delambre, in Histoire de l’astronomie du moyen-âge (Paris, 1819), pp. 63–73, gives a detailed account of al-Fargh?n?’s Elements, chapter by chapter. See also J. L. E. Dreyer, History of the Planetary Systems from Thales to Kepler (Cambridhe, 1906), passim; P. Duhem, Le sustème du monde, II (Paris, 1914), 206–214; and, concerning the relation of Sacrobosco to al-Fargh?n?, Lynn Thorndike, The Sphere of Sacrobosco and Its Commentators (Chicago, 1949), pp. 15–19. Brief accounts of al-Fargh?n? are to be found in the Encyclopaedia of Islam and in Sarton’s Introduction to the History of Science, I (Baltimore, 1927), 567.

A. I. Sabra