Al-Bīrūnī (or Bērūnī), Abū Rayḥān (or Abu’l-Rayḥān) Muḥammad Ibn Aḥmad

(b. Khwārazm [now Kara-Kalpakskaya A. S.S.R.], 4 September 973; d. Gbazna [?][now Gbazni, Afghanistan], after 1050)

astronomy, mathematics, geography, history.

Bīrūnī was born and grew up in the region south of the Aral Sea, known in ancient and medieval times as Khwārazm. The town of his birth now bears his name. The site was in the environs (bīrūn, hence his appellation) of Kāth, then one of the two principal cities of the region, located (in the modern Kara-Kalpakskaya A.S.S.R.) on the right bank of the Amu Dar’ya (the ancient Oxus) and northeast of Khīva. The second capital city of Khwārazm was jurjāniyya (modern Kunya-Urgench, Turkmen S.S.R.), on the opposite side of the river and northwest of Khīva. There also Abū Rayḥān, spent a good deal of time during the early part of his life. About his ancestry and childhood nothing is known. In verses ridiculing a certain poet (Yāqūt, p. 189; trans., Beiträge, LX, p. 62) he clail11signorance of his own father’s identity, but the statement may have been rhetorical. He very early commenced scientific studies and was taught by the eminent Khwāraznlian astronomer and mathematican Abū Naṣr Manṣūr. At the age of seventeen he used a ring graduated in halves of a degree to observe the meridian solar altitude at Kāth, thus inferring its terrestrial latitude (Taḥdīd, 249:7). Four years later he had made plans to carry out a series of such determinations and had prepared a ring fifteen cubits in diameter, together with supplementary equipment. There was, however, time only for an observation of the summer solstice of 995, made at a village south of Kāth and across the Oxus from it. At this time, civil war broke out. Bīrūnī went intohi ding and shortly had to flee the country (Taḥdīd, 87:3, 109:6–110:11). “After I had barely settled down for a few years,” he writes, “I was permitted by the Lord of Time to go back home, but I was compelled to participate in worldly affairs, which excited the envy of fools, but which made the wise pity me.”

Since these “worldly affairs” essentially affected not only Bīrūnīs personal well-being but also his scientific work, it is necessary to introduce the names of six princely dynasties with which he became directly involved.

(1) The ancient title of Khwārazmshāh had long been held by the lord of Kāth, a member of the Banū’IrĀq. Ahū Naṣr was a prince of this house (Krause, p. 3). In 995, however, the emir of Jurjāniyya attacked his suzerain, captured and killed him, and seized the title for himself (Chahār Maqāla, p. 241). It was this disturbance that caused Bīrūnī’s flight.

(2) For well over a century the Khwārazmshāhs had been dominated by the Sāmanids, a royal house of Zoroastrian origin but early converted to Islam. The Sāmānid capital was in Bukhara, about two hundred miles southeast of Khīva, from whence the dynasty ruled in its heyday an area comprising roughly all of present Afghanistan, Transoxiana, and lran. In Bīrūni’s youth this empire was rapidly breaking up. Nevertheless, in a poem written much later (Yāqūt, p. 187;trans., Beiträge, LX, p. 61) he namesas his first patron Mansūr II, almost the last of the Sāmānid line, who reigned from 997 to 999.

(3) Much farther to the west flourished the Buwayhid dynasty, which had originated in the highlands south of the Caspian and extended its domain south to the Persian Gulf and, by 945, west over Mesopotamia.

(4) Set precariously between the Sāmānids and the Buwayhids was the Ziyārid state, based in Gurgān, a city just back of the southeast corner of the Caspian shore.

(5) All these competing dynasties were menaced, and eventually absorbed, by the swift expansion of another kingdom, that of the Ghaznavids, named from Ghazna, their base in east-central Afghanistan. Sultan Maḥmūd; son of a Turkish slave and the second and greatest of the line, was two years older than Bīrūnī. By 1020 he had carved out a realm extending a thousand miles north and south, and twice as far east and west.

(6) Over these kaleidoscopic shifts there presidedat Baghdad the spectral figure of the Abbasid caliph, retaining only the shadow of power over these fragments of his ancestors’ empire. Playing a role somewhat what analogous to that of the medieval popes, he was accorded a strange religious respect by the temporal princes of Islam. Upon them the successive caliphs conferred prestige by investing them with honorificc titles and robes of honor.

To which or from which of these kingdoms Bīrūnī fled in 995 is now uncertain. It may have been then that he went to Rayy, near modern Teheran. In the Chronology(p. 338) he quotes a ribald poem on the tribulations of penury, and to illustrate it states that he was once in Rayy, bereft of a royal patron and in miserable circumstances. A local astrologer chose to ridicule his views on some technical matter because of his poverty. Later, when his circumstances improved, the same man became friendly.

At the command of the Buwayhid prince, Fakhr al-Dawla, the astronomer al-Khujandī built a large mural sextant on a mountain above Rayy. With this Fakhrī sextant, named for the ruler, he observed meridian transits during 994. Bīrūnī wrote a treatise describing this instrument (Sextant) and a detailed account of the observations (Taḥdīd, 101:20–108: 19). Part of his information was obtained from al-Khujandīin person, and since the latter died about 1000 (Suter, p. 74), the conversation between the two cannot have been long after the observations.

There is some reason for thinking that Abū Rayḥān also was in the Caspian province of Gīlān about this time. He dedicated a book (RG 7) to the lspahbad (Persian for “ruler,” or “commander”) of Gīllān, Marzubān ibn Rustam, who was connected with the Ziyārids. In the Chronology, completed about 1000 (trans., pp. 47, 191), he mentions having been in the presence of this individual, perhaps the same Ispahbad who sheltered Firdawsī, the epic poet of Iran, from the wrath of Sulṭān Maḥmūd (Browne, pp. 79, 135).

Regardless of where he had been, Bīrūnī was backin Kāth by 997, for on 24 May of that year he observed a lunar eclipse there (Oppolzer 3403), having previously arranged with Abu’l-Watā’ that the latter should simultaneously observe the same event from Baghdad (Taḥdīd. 250: 11, gives only the year; but Oppolzer 3404, on 17 November 997, was invisible from both cities). The time difference so obtained enabled them to calculate the difference in longitude between the two stations.

This year saw the beginning of the short reign of the Sāmānid Manṣūr II, If Bīrūnī ever resided at his court in Bukhara (as Bīrūni’s poem mentioned above may imply), it probably was at this time. Meantime, the ruler of Gurgān, the Ziyārid Qāhūs, had been expelled from his lands, and at Bukhara he sought support for a return to power. He succeeded in reestablishing himself at Gurgān and Bīūni either accompanied him or followed almost immediately thereafter, for about 1000 Bīrūnī dedicated to Qābūs his earliest extant major work, the Chronology(text, p. xxiv). This was by no means his first book, for in it he refers incidentally to seven others already completed, none of which are extant. Their titles indicate that he had already broken ground in the fields he later continued to cultivate, for one (RG 34) is on decimal computation, one (RG 46) on the astrolabe, one (RG 146)on astronomical observations, three (RG 42, 99, 148) on astrology, and two (RG 161, 162) are histories. By this time he also had engaged in an acrimonious correspondence with the brilliant Bukharan philosopher and physician Avicenna on the nature and transmission of heat and light. Bīūrūnī refers to him (Chronology, text, p.257) as “the youth” The appellation, coming from an individual still in his twenties, may seem less condescending when it is realized that the precocious Avicenna was still in his teens.

In the Taḥdīd (214:15–215:3), after describing the measurement of a degree along a terrestrial meridian made at the direction of the Caliph Ma’mūn, Bīrūnīwrites of his own abortive project to repeat the operation. A suitable tract of land was chosen between Gurgān and the land of the Oghuz Turks (in the deserts east of the Caspian?), but the patron, presumably Qābūs, lost interest.

The end of Abū Rayḥān’s sojourn at the Ziyārid court can be fixed within precise limits, for in 1003 he observed two lunar eclipses from Gurgān, one on 19 February and the other on 14 August. On 4 June of the following year he observed a third lunar eclipse (Canon, pp. 740, 741), but this one from Jurjāniyya. Hence, sometime in the interim he had returned to his homeland, high in favor with the reigning Khwārazmshāh. This was now a certain Abu’l‘Abbās Ma’mūn, a son of the usurper to the title mentioned above. Both Ma’mun and a brother who preceded him on the throne had married sisters of the ever more powerful and truculent Sultan Maḥmūd of Ghazna.

The bounty of the shah enabled Bīrūnī to set up at Jurjāniyya an instrument, apparently a large ring fixed in the meridian plane, which in gratitude he called the Shāhiyya ring (Canon, 612:5). He reports in various places in the Taḥdīd and the Catron some fifteen solar meridian transit observations at Jurjāniyya, the first the summer solstice of 7 June 1016, the last on 7 December of the same year. It was probably during this interlude of prosperity and royal favor that he had a hemisphere constructed, ten cubits in diameter, to be used as a plotting device for the graphical solution of geodetic problems (Taḥadīd, 38:6).

Meanwhile, Khwārazmian political affairs, in which Bīrūnī was closely involved, had been building up to a climax. The Caliph Qādir conferred upon Ma’mūn an honorific title and dispatched an envoy bearing the insignia of the award. The shah was frightened lest Maḥmūd take offense at his accepting the honor conferred directly and not through Maḥmūd as implied overlord. Ma’mūn there fore sent Bīrūnī west into the desert to intercept the embassy, take delivery of the objects, and thus forestall a public investiture.

In 1014 Maḥmūd let it be understood to Ma’mūm that he wanted his own name inserted into the khuytba, the Friday prayer for the faithful and for the reigning monarch. Ma’mūm convened an assembly of the notables, proposing that he accede to this demand, but the chiefs refused to allow him to do so, realizing that it meant the end of the region’s autonomy. Ma’mūn then sent to them Bīrūni, who, “with tongue of silver and of gold,” convinced them that their liege was only testing them by his request and that the khuytba would not be changed. At this, Maḥmūd dispatched an insulting ultimatum to the shah, demanding that he keep his nobles in line, or he, Mahmúd, would do it himself. The hapless Ma,ḥmūd introduced the sultan’s name into the Khutba in the provincial mosques, but not those of Jurjāniyya and Kath. Thereupon the Khwārazmian army revolted and killed Ma’mūn. This was all Maḥmūd needed. He marched into Khwārazm with ample forces, obtained the delivery of his sister, the Khwārazmshāh’s widow, took Kāth, on 3 July 1017, cruelly executed the insurgent leaders, and set one of his officers on the throne. The surviving princes of the local dynasty were carried off to imprisonment in various parts of his domain (Barthold, pp. 275–279).

Much of our knowledge of these events is from Bīrūnī’s extensive history of his native land, a work that has been lost except for fragments incorporated into other histories. As for Abū Rayhān himself, he also was led off by the conqueror, partly, no doubt, to grace the sultan’s court but also to remove an active partisan of the native rulers from the scene. He is next heard of in a village near Kabul, depressed and in miserable circumstances, but hard at work on the Taḥdīd (119:1–12). On 14 October 1018 he wanted to take the solar altitude, but had no instrument. He therefore laid out a graduated arc on the back of a calculating board (takht) and, with a plumb line, used it as an improvised quadrant. On the basis of the results obtained, he calculated the latitude of the locality.

The next firm date at our disposal is 8 April 1019, when he observed a solar eclipse from Lamghān (modern Laghman?), north of Kabul. He uses this, and the lunar eclipse mentioned below, to comment sarcastically upon the ignorance of the local astronomers.

Sachau has shown (India, trans., I, xi) that Bīrūnī’s relations with Maḥmūd were never good, although the stories in the Chahār Maqāla (text, pp. 57–59) alleging cruel and arbitrary treatment of the savant by the sultan are doubtless apocryphal. It is evident that Abū Rayhān received some sort of official support for his work, for in the Canon (p. 609) he writes of having determined the latitude of Ghazna by a series of observations carried out between 1018 and 1020 with an instrument he calls the Yamīnī ring. A title bestowed upon Sultan Maḥmūd by the caliph was Yamīn al-Dawla (“Right Hand of the State”). No doubt this ring was a monumental installation named, as was the custom, for the ruler patron.

It is also clear that Bīrūnī’s interests in Sanskrit and in Indian civilization are due to his having become an involuntary resident of an empire that had by then expanded well into the Indian subcontinent. Already in 1002 Maḥmūd had conquered the district of Waihand, on the Indus east of Ghazna. By 1010 he had subjugated Multan and Bhatinda, the latter 300 miles east of the Indus. Twice repulsed (in 1015 and 1021) from the borders of Kashmir, by 1022 he had penetrated and subdued the Ganges valley to a point not far west of Benares. In 1026 Maḥmūd led a raid due south from Ghazna all the way to the Indian Ocean. From Somnāth, at the tip of the Kathiawar Peninsula, he carried off immensely valuable booty, as well as fragments of the phallic idol in the temple. One of the pieces was laid at the entrance to the Ghazna mosque, to be used as a footscraper by the worshipers (India, trans., II, 103; Nāzim, ch. 8).

Abū Rayḥāan profited from these events by travel and residence in various parts of India. The names of many of the places he saw are known, but no dates can be given for his visits. They were confined to the Punjab and the borders of Kashmir. Sachau (India, text, p. xii) lists some eleven Indian towns whose latitudes Bīrūnī reports as personally determined by him. Bīrūnī himself writes that while living (in detention?) at Nandana Fort, he used a nearby mountain to estimate the earth’s diameter (Taḥdīd, 222:10). The installation at Nandana, taken by Maḥmūd in 1014, commanded the route by which he, the Moghuls after him, and Alexander the Great long before, penetrated the Indus valley. Bīrūnī’s temporary residence overlooked the site where, in the face of King Poros and his elephants, Alexander effected his famous crossing of the Jhelum River, the classical Hydaspes (Stein).

It is also clear that Bīrūnī spent a great deal of time at Ghazna. The cluster of recorded observations made by him there commences with a series of meridian solar transits covering the summer solstice of 1019, and includes the lunar eclipse on 16 September of the same year (Taḥdīd 291:9). He continued to observe equinoxes and solstices at Ghazna, the last being the winter solstice of 1021. In fact, this is the latest of Bīrūnī’s observations that has been preserved. At about this time, according to Barani (Canon, III, vii), he completed his treatise on Shadows.

In 1024 the ruler of the Volga Turks sent an embassy to Ghazna. These people had trade relations with inhabitants of the polar regions, and Bīrūnī questioned members of the mission to supplement his knowledge of these lands. One of the ambassadors asserted in the sultan’s presence that in the far north the sun sometimes did not set for days on end. Maḥmūd at first angrily put this down as heresy, but Abū Rayḥān convinced him that the report was both credible and reasonable (Commemoration Volume, p. 235; Yāqūt).

By the late summer of 1027 the treatise on Chords was completed (according to the Patna MS). During the same year a Chinese and Uighur Turkish embassy came to Ghazna, and from this mission Bírúní obtained geographical information on the Far East which he later incorporated into the Canon (Commemoration Volume, p. 234).

In 1030 Sultan Maḥmūd died, and the succession was disputed between two of his sons for a short period. Bīrūni finished the India during this interim and, perhaps because of the uncertain political situation, refrained from dedicating it to any particular patron. Within the year Mas‘ūd, the elder son, won the crown. His accession brought about a drastic improvement in the situation of his most famous scientist, and Bīrūni named the Canon for the new ruler amid “a farrago of high-sounding words” in the preface (India, trans., I, xii).

Perhaps it was the change of regime that enabled him to revisit his native land. By whatever means, he made at least one trip back, for in the Bibliography he writes that for over forty years he had sought a certain Manichaean work, a copy of which he at length procured while in Khwārazm (Chronology, text, p. xxxvi). In the same source Bīrūni relates that after he was fifty years old he suffered from a series of serious illnesses, and in his distress inquired of several astrologers concerning the length of his life. Their answers diverged wildly, and some were patently absurd. At the end of his sixty-first (lunar?) year he began improving, and had a dream in which he was seeking the new moon. As its crescent disappeared, a voice told him that he would behold 170 more of the same.

Mas‘ūd was murdered by his officers and succeeded by his son Mawdūd in 1040. During Mawdūd’s eight year reign, Bīrūni wrote the Dastur (RG 167) and the Gems. Of his subsequent activities we have no knowledge, save that in the Pharmacology (p. 7) he notes having passed his eightieth (lunar?) year; his eyesight and hearing are failing, but he is still hard at work with the assistance of a collaborator. Thus the date of his death given by Ghadanfar as 13 December 1048 is incorrect; Bīrūni outlasted his third Ghaznavid patron and achieved the life-span foretold in his dream.

When he was sixty-three years old, Bīrūni prepared a bibliography of the works of the physician Muḥammad ibn Zakariyya al-Razi, to which he appended a list of his own books. This runs to 113 titles (not counting twenty-five additional treatises written “in his name” by friends), partially arranged by subject matter and occasionally with a brief indication of the contents. Most of the entries also give the length of the particular manuscript in folios. The list is incomplete, for Abūu Rayhan lived at least fourteen years after this, working until he died. Moreover, seven additional works by him are extant and many more are named, some in his own writings and others in a variety of sources. All told, these come to 146. The reckoning is uncertain, for some titles counted separately may be synonyms, and additional items may well turn up in the future.

There is a wide range in size of the treatises. Several amount to only ten folios each, while, at the other extreme, three lost astronomical works run to 360, 550, and 600 folios respectively. Largest of all is the India, at 700 folios. The English translation of the latter, incidentally, takes up 654 pages of small type, so that one of Bīrūni’s folios is roughly equivalent to a modern printed page. The mean length of the seventy-nine books of known size is very nearly ninety folios. Assuming that the same holds for all 146 works, it follows that Bīrūni’s total output is on the order of 13,000 folios (or pages), consisting for the most part of highly technical material, including numerical tables, the results of involved computations, and analyses of materials from multifarious sources—a formidable accomplishment indeed.

The classification attempted in the table below is only approximate; for instance, a book placed in the geographical category could legitimately be classed as primarily geodetic, and so on. Practically nothing Bīrūni wrote confines itself strictly to a single subject, and in many cases where the title alone survives, an informed guess is our only recourse. Nevertheless the table gives a reasonable breakdown of the man’s activity. In the second column a “major work” has been taken arbitrarily as anything of 200 folios or more. The third and fourth columns show, respectively, the compositions known to exist in manuscript form and the numbers of these that have thus far been printed. Roughly four-fifths of Bīrūnī’s work has vanished beyond hope of recovery. Of what has survived, about half has been published. Most of the latter (with the notable exception of the Cannon) has been translated into other languages and has received some attention from modern scholars.

The table also clearly reveals both scope and areas of concentration. Bīrunū’ interests were very wide and deep, and he labored in almost all the branches of science known in his time. He was not ignorant of philosophy and the speculative disciplines, but his bent was strongly toward the study of observable phenomena, in nature and in man. Within the sciences themselves he was attracted by those fields then susceptible of mathematical analysis. He did serious work in mineralogy, pharmacology, and philology, subjects where numbers played little part; but about half his total output is in astronomy, astrology, and related subjects, the exact sciences par excellence of those days. Mathematics in its own right came next, but it was invariably applied mathematics.

Below are brief descriptions of most of Bīrūni’s works that are still available. They are our best sources for estimating the extent and significance of his accomplishments.

The Chronology. The day, being the most apparent and fundamental chronological unit, is the subject of the first chapter. Bīrūni discusses the advantages of various calendric epochs—sunset or sunrise (horizon-based), noon or midnight (meridian-based)—and names the systems that use each. Next the several varieties of year are defined—lunar, solar, lunisolar, Julian, and Persian—and the notion of intercalation is introduced. Chapter 3 defines and discusses the eras of the Creation, the Flood, Nabonassar, Philip Arrhidaeus, Alexander, Augustus, Antoninus, Diocletian, the Hegira, Yazdigird, the Caliph Mu‘tadid, the pre-Islamic Arabs, and Bīrūni’s native Khwārazm. Chapter 4 discusses the Alexander legend, giving sundry examples of pedigrees, forged and otherwise. Next are lists of the month names, with variants, used by the Persians, Soghdians, Khwārazmians, Egyptians, Westerners (Spaniards?), Greeks, Jews, Syrians, pre-Islamic Arabs, Muslims, Indians, and Turks. In this chapter, the fifth, Bīrūni commences his very extensive description of the Jewish calendar. (Except for the work of al-Khwarizmi, another Muslim, his is the earliest extant scientific discussion of this calendar.)

Chapter 6 culminates with a table (trans., p. 133) giving the intervals in days between each pair of the eras named above. This is preceded, however, by chronological and regnal tables in years (sometimes with months and days) for the Jewish patriarchs and kings; the Assyrians, Babylonians and Persians; the Pharaohs, Ptolemies, Caesars, and Byzantine emperors; the mythical Iranian kings; and the Achaemenid, Parthian, and Sasanian dynasties. Where tables from different sources conflict, all are given in full, and there are digressions on the length of human life and the enumeration of chessboard moves.

Chapter 7 continues the exhaustive discussion of the Jewish calendar, but includes a derivation of the solar parameters, a table of planetary names, and the Mujarrad table giving the initial weekdays of the mean (thirty-year cycle) lunar year.

Chapter 8 is on the religions of various pseudo prophets, the most prominent being the Sabians (or Mandaeans, alleged to be followers of Būdhāsaf = Bodhisattva!), Zoroastrians, Manichaeans, and adherents of Mazdak.

The remaining half of the book (save the last chapter) describes the festivals and fasts of the following peoples: Chapter 9, the Persians; 10, the Soghdians; 11 and 12, the Khwārazmians; 13, the Greeks (including material from Sinān ibn Thābit ibn Qurra on the parapegmatists); 14, the Jews; 15, the Melchite Christians; 16, the Jewish Passover and Christian Lent; 17, the Nestorian Christians; 18, the Magians and Sabians; 19, the pre-Islamic Arabs; 20, the Muslims. The concluding chapter, 21, gives tables and descriptive matter on the lunar mansions, followed by explanations of stereographic projection and other plane mappings of the sphere.

The Astrolabe. Amid the plethora of medieval treatises on the astrolabe, this is one of the few of real value. It describes in detail not only the construction of the standard astrolabe but also special tools used in the process. Numerical tables are given for laying out the families of circles engraved on the plates fitting into the instrument. Descriptions are also given of the numerous unusual types of astrolabes that had already been developed in Bīrūnī’s time. As for the underlying theory, not only are the techniques and properties of the standard stereographic projection presented, but also those of certain nonstereographic and nonorthogonal mappings of the sphere upon the plane.

The Sextant. This two-page treatise describes the giant mural instrument for observing meridian transtis built instrument for observing meridian transits built by al-Khujandī at Rayy for Fakhr al-Dawla, and perhaps seen by al-Bīrūni, although he does not say so.

The Tahaldīd. The central theme is the determination of geographical coordinates of localities. In particular, Bīrūni sets out to calculate the longitudinal difference between Baghdad and Ghazna. Several preliminary problems present themselves: latitude determinations, inclination of the ecliptic, the distribution of land masses and their formation, length of a degree along the terrestrial meridian, and differences in terrestrial longitudes from eclipse observations. Techniques and observations used by Bīrūni and by others are reported. Application is made of a theorem of Ptolemy’s that gives the longitudinal difference between two places in terms of the latitude of each and the great circle distance between them. The latter was estimated from caravan routes and lengths of stages. Successive computations then yield the differences in longitude between Baghdad, Rayy, Jurjāniyya, Balkh, and Ghazna, and likewise along a southern traverse including Shiraz and Zaranj. The final result is in error by only eighteen minutes of arc.

The Densities. By means of an ingenious form of balance exploiting Archimedes’ principle, Bīrūni worked out a technique for ascertaining the specific gravity of a solid of irregular shape. He reports very precise specific gravity determinations for eight metals, fifteen other solids (mostly precious or semiprecious stones), and six liquids.

The Shadows. As its full title indicates, this is a comprehensive presentation of all topics known to Bīrūnī to be connected with shadows. Of the total of thirty chapters, the first three contain philosophical notions about the nature of light, shade, and reflection. There are many citations from the Arabic poets descriptive of kinds of shadows.

Chapter 4 shows that the plane path traced in a day by the end point of a gnomon shadow is a conic. The next two chapters discuss the properties of shadows cast in light emanating from celestial objects. Chapters 7 and 8 define the shadow functions (tangent and cotangent) and explain the origins of the gnomon divisions used in various cultures: the Hellenistic 60, Indian 12, Muslim 7 or 6–1/2. The succeeding three chapters explain rules for converting between functions expressed in different gnomon lengths and for conversions into the other trigonometric functions (sine, secant, and their cofunctions, together with their various parameters), and vice versa. Chapter 12 gives tangent-cotangent tables for the four standard gnomon lengths and discusses interpolation. The next two chapters explain how to engrave the shadow functions on astrolabes. There follows, in Chapter 15, a discussion of gnomon shadows cast on planes other than horizontal, and on curved surfaces. Chapters 16 and 17 consider the effect of solar declination and local latitude on the meridian shadow length. A number of nontrigonometric approximate Indian rules are given. Chapters 18–21 list a variety of meridian-determination methods (including one from the lost Analemma of the first-century B.C. Diodorus). Chapter 22 is on daylight length and rising times of the signs as functions of the local latitude and the season. Here and in the next two chapters (on determining the time of day from shadows) rules are reproduced from numerous Indian, Sasanian, and early Islamic documents, many no longer extant. Some early Muslim rules are in Arabic doggerel written in imitation of Sanskrit slokas. Chapters 25 and 26 define the time of the Muslim daily prayers, some in terms of shadow lengths. Chapter 27 shows that in many situations on the celestial sphere, Menelaus’ theorem gives relations between shadow functions. The concluding three chapters describe Indian and early Islamic techniques for calculating terrestrial and celestial distances by the use of shadows.

The Chords. The book begins by stating the following theorem: A, B, and C, three points on a circle, are so situated that AB>BC. From D, the midpoint of arc AC, drop a perpendicular, DE, to the chord AB. Then the foot of the perpendicular bisects the broken line ABC. There follow a number of proofs of this theorem, attributed to sundry Greek and Islamic mathematicians, some otherwise unknown to the literature. A second theorem, that in the configuration above, is also followed by a long series of proofs. The same thing is done for the expression . Then comes a set of metric relations between chords, based on the foregoing and leading up to propositions useful for calculating a table of chords (or sines).

The Patañjali. Cast in the form of a series of questions put by a hermit student and the answers given by a sage, this book deals with such philosophical and mystical topics as liberation of the soul and its detachment from the external world, the attributes of God, the power of spirit over the body, and the composition of the universe.

The Tafhīm. A manual of instruction in astrology, well over half of the book is taken up with preliminaries to the main subject. Persian and Arabic versions are extant, both apparently prepared by Bīrūni himself. It is arranged in the form of questions and answers. There are five chapters in all, the first (thirty-three pages in the Persian edition) on geometry, ending with Menelaus’ theorem on the sphere. The second (twenty-three pages) is on numbers, computation, and algebra. Chapter 3, the longest (229 pages), deals with geography, cosmology, and astronomy. From it a complete technical vocabulary may be obtained, as well as sets of numerical parameters, some of them uncommon. The next chapter (thirtyone pages) describes the astrolabe, its theory and application. Only the last chapter (223 pages) is on astrology as such, but it is complete and detailed.

The India. The book commences with a prefatory chapter in which the author states that the subject is difficult because Sanskrit is not easy; there are extreme differences between Indians and non Indians; and Indian fear and distrust has been exacerbated by Muslim conquests. The book will not be polemical and, when appropriate, Indian customs and beliefs will be compared with cognate ones of the Greeks.

Chapters 2–8 are on religion and philosophy: the nature of God, the soul, matter, mysticism, paradise, and hell. Chapters 9, 10, and 11 describe, respectively, the Hindu castes, laws concerning marriage, and the construction of idols. Chapters 12, 13, and 14 are on categories of literature: sacred, grammatical, and astronomical. The latter gives a table of contents of the Brāhmasphuṭasiddhānta. Chapter 15 presents tables of metrological units and gives various approximations to the number π. The next two chapters are on Indian systems of writing, number names, chess rules, and superstitions. Chapter 18 is geographical; in particular, sixteen itineraries are given with the distances in farsakhs between successive stages. Chapters 19–30 present astronomical and cosmological nomenclature, legends, and theories. Chapter 31 cites the geodetic parameters used by various astronomers, and the latitudes (observed by Bīrūni) of a number of Indian cities. Chapters 32–53 are on Indian notions of time, including detailed definitions of the hierarchies of enormous cycles—the yugas, kalpas, and so on—interspersed with accounts of sundry religious legends. Calendric procedures are given in great profusion. Chapters 54–59 are astronomical, dealing with the computation of mean planetary positions, the sizes and distances of the planets, heliacal risings, and eclipses. The remainder of the book is largely astrological, but includes chapters on rites, pilgrimages, diet, lawsuits, fasts, and festivals.

The Ghurra. This is an example of an Indian karana, a handbook enabling the user to solve all the standard astronomical problems of his time, with the emphasis on actual computation rather than on theory. Hence it resembles an Islamic zīj (astronomical handbook). Topics include calendric rules; length of daylight; determination of the astrological lords of the year, month, day, and hour; mean and true positions of the sun, moon, and planets; time of day; local latitude; solar and lunar eclipses; and visibility conditions for the moon and the planets. Bīrūnī has added worked-out examples, in particular, conversions from the Šaka calendar into the Hegira, Yazdigird, and Greek (so-called era of Alexander) calendars. Otherwise, he states, in his translation he has made no changes.

In general, the methods are those common to medieval Indian astronomy, but the parameters are not identical with any extant Sanskrit document. For instance, the radius of the defining circle for the sine function is 200 minutes, and the increment of arc, the kardaja, is ten degrees.

The Canon. This most comprehensive of Bīrūni’s extant astronomical works contains detailed numerical tables for solving all the standard problems of the medieval astronomer-astrologer. But it also has much more in the way of observation reports and derivations than the typical zīj. It is organized in eleven treatises (maqāla) that are further subdivided into chapters and sections.

Treatises 1 and 2 set forth and discuss general cosmological principles (that the earth and heavens are spherical, that the earth is stationary, etc.), units of time measurement, calendars, and regnal and chronological tables. This covers much of the ground gone over in the Chronology, but the chapter on the Indian calendar is additional.

Treatises 3 and 4 are on plane and spherical trigonometry respectively. There are tables of all the standard trigonometric functions, more extensive and precise than preceding or contemporary tables. Methods of solving many problems of spherical astronomy appear, together with tables of ancillary functions: oblique ascensions, declinations, and so on.

Treatise 5, on geodesy and mathematical geography, reworks much of the subject matter of the Taḥdīd. A table gives the geographical coordinates of localities.

Treatises 6 and 7 are on the sun and moon, respectively. Here (and with planetary theory farther on) the abstract models are essentially Ptolemaic, but many parameters are independently derived on the basis of all available observations (including Bīrūnī’s own).

Treatise 8 treats of eclipse computations and the first visibility of the lunar crescent.

Treatise 9, on the fixed stars, includes a star table with 1,029 entries (cf. Ptolemy’s 1,022). Magnitudes according to Ptolemy and to al-Sūfī are given.

The next treatise is on the planets, with tables and text for calculating longitudes, latitudes, stations, visibility, distances, and apparent diameters.

The concluding treatise is on astrological operations, describing various doctrines for calculating the astrological mansions, projection of the rays, the taysīr the sectors (niṭāqāt), transits, and the curious cycles apparently developed by Abū Ma‘shear.

The Transits. This book describes the various categories of astrological phenomena to which the term mamarr (transit or passage) was attached. One planet was said to transit another if it passed the other planet in celestial longitude, or celestial latitude, or in its relative distance from the earth. The notion seems to have been developed by astrologers using non Ptolemaic astronomical doctrines described in documents no longer extant. Hence the main interest of the work is the assistance it gives toward the reconstruction of these lost Indian, Sasanian, and early Islamic theories.

The Gems. The work is organized in two parts, the first being on precious and semiprecious stones, the second on metals. Bruni brings together material from Hellenistic, Roman, Syriac, Indian, and Islamic sources, supplemented by his own observations. In addition to descriptions of the physical properties of the various substances, there are very extensive etymological discussions of the technical terminology in many languages and dialects, and numerous illustrative quotations from Arabic poetry. The principal mines and sources of supply are cited. Relative weights of the metals with respect to gold are given, and there are tables showing the prices of pearls and emeralds as functions of size.

The Pharmacology. The book commences with an introduction in five chapters. The first presents an etymology for the Arabic word for druggist. The first presents an etymology for the Arabic word for druggist. The second gives technical terminology for categories of drugs. The next chapter is on the general theory of medicaments. In the fourth and fifth chapters Bīrūni states his preference for Arabic over Persian as a language of science, and he names polyglot dictionaries available to him.

The main body of the work is an alphabetical listing of drugs comprising about 720 articles. For a typical entry the name of the substance is given in Arabic, Greek, Syriac, Persian, and an Indian language, and sometimes also in one or more less common languages or dialects: Hebrew, Khwārazmian, Tocharian, Zabuli, and so on. There follows a full presentation of the Arabic variants and synonyms, liberally illustrated with quotations from the Arabic poets. The substance is described, its place or places of origin named, and its therapeutic properties given, although Bruni disclaims medical competence on his own part. Sources are fully and critically mentioned.

Abū Rayḥān’s dominant trait was a passion for objective knowledge. In pursuit of this he early began studying languages. His mother tongue was khwārazmain, an Iranian language in which, he wrote, it would be as strange to encounter a scientific concept as to see a camel on a roof gutter (mīzāb) or a giraffe among though horses (‘irāb, an example of rhymed prose). Therefore he acquired a deep knowledge of both Arabic and person. The former, in spite of the ambiguity of its written characters, he esteemed a proper vehicle for the conveyance of science, whereas the latter he deemed fit only for the recital of bedtime stories (al-asmār al-layliyya) and legends of the kings (al-akhbār al-kisrawiyya more rhymed prose; Pharmacology, p. 40). Of Greek, Syriac, and Hebrew he attained at least sufficient knowledge to use dictionaries in these languages. His command of Sanskrit, on the other hand, reached the point where, with the aid of pandits he was able to translate several Indian scientific works into Arabic, and vise versa. He took obvious delight in Arabic poetry, composed verses himself, and liberally interlarded his writings with quotations from the classics.

Thus equipped, he made full use of all the documents that came to his hand (many of which have since disappeared), exercising a critical faculty that extended from the minutiae of textual emendations to the analysis of scientific theories. A strong sense of history permeates all his writings, making them prime sources for studying the work of his predecessors, as well as his own and that of his contemporaries.

Bīrūnī’ pursuit of the truth was not confined to the written or spoken word. He had a strong penchant for firsthand investigation of natural phenomena, exercised at times under very trying circumstances. Along with this went an ingenuity in the devising of instruments and a flair for precision in observations. Because of this feeling for accuracy, and because of a well-founded fear of losing precision in the course of calculations, he tended to prefer observational methods that yielded direct results, as against techniques requiring extensive reduction by computation.

Speculation played a small role in his thinking; he was in full command of the best scientific theories of his time, but he was not profoundly original or a constructor of new theories. His attitude toward astrology has been debated. He spent a great deal of time in serious study of the subject, but Krause (p. 10) has collected passages in which Bīrūnī not only heaps ridicule upon ignorant or unscrupulous astrological practitioners, but indicates disbelief in the basic tenets of this pseudo science. Krause also reminds us that there were many centuries when the casting of horoscopes was the only way by which an astronomer could support himself in the exercise of his profession.

As for religion, Bīrūnī was doubtless a sincere Muslim, but there is no firm evidence of his having been an adherent of any particular sect within the faith. In the Chronology (trans., pp. 79, 326), written at the court of Qābūs, are passages that have been interpreted as betraying a Shī (hence anti-Arab and pro-Persian) bent. On the other hand, the Pharmacology, compiled under Ghaznavid patronage, represents the author as an orthodox Sunnī. Probably these two situations reflect no more than the fact that the two patrons were Shī‘i and Sunnī, respectively. From time to time Bīrūnī inveighs harshly against various groups, but the criticism is of particular acts or attitudes, not of the group as such. Thus his strictures against the Arab conquerors of Khwārazm were called forth, not because they were Arab, or alien, but because they were Arab, or alien, but because they destroyed ancient books. Concerning the Christian doctrine of forgiveness he writes, “Upon my life, this is a noble philosophy, but the people of this world are not all philosophers…. And indeed, ever since Constantine the Victorious became a Christian, both sword and whip have ever been employed” (India, trans., II, 161).

In these, and in most matters, Bīrūnī had a remarkably open mind, but his tolerance was not extended to the dilettante, the fool, or the bigot. Upon such he exercised a broad and often crude sarcasm. Upon his showing an instrument for setting the times of prayer to a certain religious legalist, the latter objected that it had engraved upon it the names of the Byzantine months, and this constituted an imitation of the infidels. “The Byzantines also eat food,” stated Abū Rayḥān. “Then do not imitate them in this!” and he ejected the fellow forthwith (Shadows, 37: 9).

Such were the life, labors, and character of a man known to his contemporaries as the Master (al-Ustādh). Unknown in the medieval West, except perhaps by the garbled name Maītre Aliboron, fame have been secure in his own lands from his time until the present.

BIBLIOGRAPHY

The standard bibliographical work on Bīrūnī is D. J. Boilot, “L’oeuvre d’al-Beruni. Essai bibliographique” in Mélanges de l’Institut dominicain d’études orientales, 2 (1955), 161–256; and “Corrigenda et addenda,” ibid., 3 (1956), 391–396; no attempt has been made here to duplicate it. A good deal of material has, of course, appeared since it was published in 1955.

For points of view somewhat different from that expressed in the text, see Boilot’s article on al-Bīrūnī in the new ed. of the Encyclopaedia of Islam, Krause’s paper (cited below), and Sachau’s perfaces to the text and to the translation of the Chronology and the India. RG stands for “Répertoire général,” the numbered listing of Bīrūnī’s works in Boilot.

I. Original Works. Following are Bīrūnī’sw extant major works, listed alphabetically.

Astrolabe (RG 46). The Arabic title is Kitāb fī istī‘āb al-wujūh fī ṣan’at al-asṭurlāb. Several MSS exist (see Boilot), but the text has not been published. Sections of it have, however, been translated and studied.

Bibliography (RG 168). Bīrūnī calls this Risala fī fihrist kutub Mutḥammad b. Zakariyyā al-Rāzī. The text was published by Paul Kraus as Epître de Beruni contenant le répertoire des ouvrages de Mutḥammad b. Zakariyyā al-Rāzī (Paris, 1936). The text of the part giving Bīrūnī’s own bibliography appears in the text edition of the Chronology, pp. xxxviii-xxxxviiii. It is translated into German in Wiedemann’s “Beiträge,” LX.

Canon (RG 104). The Arabic text has been published as al-Qānūn al-Masudi (Canon Masudicus), 3 vols. (Hyderabad-Dn., 1954–1956). References in the article are to page and line of the printed text, pagination of which is continuous, not commencing anew with each volume. A Russian translation, in preparation by P. G. Bulgakov, M. M. Rozhanskaya, and B. A. Rozenfeld, will be Vol. V of the Selected Works.

Chords (RG 64). There are three MS versions of this work: (1) Leiden Or. 513(5) = CCO 1012; (2) Bankipore Arabic MS 2468/42 = Patna 2,336, 2519/40; (3) Murat Molla (Istanbul) 1396. The Leiden version has been published in translation and with a commentary, both by H. Suter, as “Das Buch der Auffindung der Sehnen im Kreise….,” in Bibliotheca mathematica, 11 (1910), 11–78. The text of version (2) has been published as the first of the four Rasāil (Arabic for treatises). This contains, however, extraneous material, part of which is probably not by Bīrūnī, and part probably a fragment of RG 11. Many topics in (2) and (3) are missing from (1), and those parts that are in common are in drastically different orders. Two recensions by Bīrūnī himself are indicated. See H. Hermelink, in Zentralblatt für Mathematik und ihre Grenzgebiete, 54 (1956), 3; and A. S. Saidan, in Islamic Culture, 34 (1960), 173–175. Many of the additional sections in (2) and (3) are described by E. S. Kennedy and Ahmad Muruwwa in Journal of Near Eastern Studies, 17 (1958), 112–121. A composite Arabic text based on (2) and (3) was published by A. S. Demerdash as Istikhrāj al-awtar fi’l-daira (Cairo, 1965). There is a Russian translation by C. A. Krasnova and L. A. Karpova, with commentary by B. A. Rosenfeld and C. A. Krasnova: Iz istorii nauki i texniki v stranax Vostoka, III (Moscow, 1963).

Chronology (RG 105). In Arabic this is al-Āthār al-bāqiyamin al-qurūn al-khāliya. It was edited by E. Sachau as Chronologies orientalishcher Voelker von Alberunt (Leipzig, 1878, 1923; repr. Baghdad, 1963). The parts missing from Sachau’s text are given by K. Garbers and J. Fūck in J. Fūck, ed., Documenta Islamica inedita (Berlin, 1925), pp.45–98. It was translated into English by Sachau as The Chronology of Ancient Nations (London, 1879). The Russian translation by M. A. Sal’e, Pamyatiki minuvvshikh pokolenii, is Vol. I of the Selected Works (Tashkent, 1975).

Densities (RG 63). This work’s Arabic title is Maqāla fi’lnisab allatī bayn al-filizzāt wa’l-jawāhir fi’l-ḥajam (“Treatise on the Ratios Between the Volumes of Metals and Jewels”) The text has never been published, but portions of it have been taken over by other authors and have been studied in modern times.

Gemes (RG 156). Known as the Kitāb-al-jamā’rifatal-jawāhir, this text was edited by F. Krenkow (Hyder-abad-Dn., 1936). Krenkow also translated the text, but only the chapter on pearls has been published (see Boilot). There is, however, a translation by A. M. Beleskii-Mineralogiya (Moscow, 1963).

Ghurra. The Ghurrat al-zījāt is Bīrūnī’s Arabic translation of the Sanskrit astronomical handbook called Karanatilaka (forehead caste markof the Karanas), by one Vijayanandin or Vijaya Nanda. The original text is not extant, but a MS of the translation is in the Dargah Library of Pir Muhmmed Shah, Ahmadabad. Portions of the Arabic text, with English translation, and a commentary were published in installments by Sayyid Samad Husain Rizvi in Islamic, Culture, 37 (1963), 112—130, 223—245, and 39 (1965), 1—26, 137—180. Another text, translation, and commentary, by M. F. Qureshi, exist in typescript but have not been published.

India (RG 936). Also known as Kitāb fi taḥqiq ma li’l-Hind…, this was edited by E. Sachau (London, 1888). A later edition has been published by the Osmania Oriental Publications Bureau (Hyderabed-Dn., 1958). Translated by E. Sachau as Al-Beruni’s India, 2 vol. (London, 1910). Translated into Russian by A. B. Khalidov and Y. N. Zavadovskii as Vol. II of Selected Works (Tashkent, 1963).

patañjail (RG 98). Bīrūnī’s Arabic translation of this Sanskrit work is extant only in an incomplete MS edited by H. Ritter as Al-Bīrūnī’s Übersetzung des Yoga-Sūtra des Patañjali,” in Oriens, 9 (1956), 165–200. See Boilot.

Pharmacology (RG 158). The Arabic title of this is Kitāb al-ṣaydala fi’l-ṭibb. There is no editen of the entire work. M. Meyerhof translated it into German, but of this only the introduction has been published, together with the corresplonding part of the Arabic text and an extremely valuable foreword and commentary: “Das Vorwort zur Drogenkunde des Beruni,” in Quellen und Studien zur Geschichte der Naturwissenschaften, 3 (1932), 157–208. A Russian translation, in preparatilon by U. I. Kazimov, will be Vol. IV of Selected Works.

Rasā’ilu-l-Birunt. This is the Arabic text of RG 64, 15, 45, and 38, published by Osmania Oriental Publications Bureau)Hyderabed-Dn., 1948).

Selected Works (Izbrannye proizvedeniya). Bīrūnī’s extant works are being publuished in Russian by the Academy of Sciences of the Uzbek S.S.R. Volumes in print or in preparation are listed by individual titles.

Sextant (RG 169). The Ḥikāyat al-ālāt al-musammāt al-suds al-fakhrī (“Account of the Instrument Known as the Fskhri Sextant”) is MS 223, pp. 10–11, of the Univ. of St. Joseph, Beirut. It was edited by L. Cheikho in Al-Masdhriq, 11 (1908), 68–69. With minor changes, this small treatise was copied without acknowledgment by Abu’-Ḥasan al-Marrākushi as part of larger work. Text and French translation appear,”, L. A. Sédillot, “Les instruments astronomiques des arabes,” in Mémories… à l’Académie royale des inscriptions…, 1st ser., 1 (1844), 202–206.

Shadows (RG 15). The text has been published as the second of the Rasā’il with the title Kitāb fī ifrād al-maqāl fi aqmr al-ẓila (“The Exhaustive Treatise on Shadows”). An English translation has been made by E. S. Kennedy, but publication awaits completion of the commentary. References to the Shadows made in the article are to page and line of the Published text.

Tafhīm (RG 73). This is the Kitāb al-tafhīm li-awā’il ṣina‘at al-tanjīm. R. Ramsay Wright published an edition of the Arabic text with English translation as The Book of Instruction in Art of Astrology (London, 1934). Bīrūnī’s Persian version was published by Jalāl Huma’i (Teheran, 1940).

Taḥdīd (RG 19). The Arbic title is Taḥdīd nihāyāt al-amākīn li-taṣhih masāfāt al-masākin and the work is extant in thde unique Istanbul MS Faith 3386. The Arabic text was published by P. Bulgakov as a special number of the Arab League joutrnal, Majallat ma‘had ai-makhṭūṭāṭ al-‘arabiyya (Cairo, 1962). Translated into Russian by P. G. Bulgakov as Geodeziya, vol. III of Selected Works (Tashkent, 1966). An English translation by Jamil Ali is The Determination of the Coordinates of Cities, al-Bīrūnī’s Tahdīd al-Amākin (Beirut, 1967). References in the article to the Tahdīd are to page and line of the published text.

Transits (RG 45). In Arabic this is Tamhīd al-mustaqarr li-taqḥqīq ma‘na al-mamarr (“Smoothing the Basis for an Investigation of the Meaning of Transits”). The text has been published as the third of the Rasa’il. A translation by Mohammand Saffouri and Adnan Ifran, with commentary by E. S. Kennedy, is Al-Bīrūnī on Transits (Beriut, 1959).

II. Secondary Literature. Works referred to paren thetically in the text, by author and page, are W. Barthold, Turkestan Down to the Mongol Invasion, 2nd ed. (London, 1928); E. G. Browne, A Literary of Persia, II (Cambridge, 1928); Chahār Maqāla of Aḥmad ibn ‘Ali an-Niẓāmī al-‘Arṭdias-Samargandī, Mirza Muḥammad ibn ‘Abd’l-Wahhab, ed. (Leiden-London, 190); Iran Society, Al-Bīrūnī commemoration Volume, A. H. 362-A. H. 1362 (Calcutta, 1951); Max Krause, “Al-Biruni. Ein iranischer Forscher des Mittelaters,” in Der Isalam, 26 (1940), 1–15; Muḥammad Näzim, The life and Times of Sulṭān Muḥmūd of Ghazna (Cambridge, 1931); Aurel Stein, “The Site of Alexander’s Passing of the Hydaspes and the Battle Withy Poros,” in Geographical Journal, 80 (1932), 31–46; Heinrich Suter, “Die Mathematiker und Astronomen der Araber…,” in Abhandlungen zur Geschichte der mathematischen Wissenschaften…, X (Leipzig, 1900); Eilhard Wiedeman et al., “Beitrôge zur Geschichte der Naturwissenchaften,” in Sitzungsberichte der Physikalish-medizinischen Sozietôt in Erlangen; and Yāqütal-Rumi, Shihāb al-Din, Abu ‘Abdallah, Mu‘jam al-udabā’ (= Irshād al-arūb ila ma‘rifat al-adūb), XVII (Cairo, 1936–1938).

E. S. Kennedy

Abu Rayhan al-Biruni

Abu Rayhan al-Biruni (973-ca. 1050), a Moslem astronomer, mathematician, geographer, and historian, was the most acute interpreter of India to Islam in the Middle Ages.

Al-Biruni was born near Kath in Khwarizm (now a part of Uzbekistan) on Sept. 4, 973. His teacher in astronomy and mathematics was the eminent Abu Nasr Mansur, a member of the family then ruling at Kath. Al-Biruni made several observations with a meridian ring at Kath in his youth. In 995 the attack on the ruler of Khwarizm by the ruler of Jurjaniya drove al-Biruni into exile, presumably to Rayy, where he discussed with the astronomer al-Khujandi the latter's observations with a mural sextant. AlBiruni later wrote a treatise on this instrument and gave a detailed account of the observations in his Tahdid.

In 997 al-Biruni returned to Kath, where he observed a lunar eclipse that Abu al-Wafa observed in Baghdad; on the basis of the time difference they determined the longitudinal difference between the two cities, one of the few instances in which this method, the only secure one available in antiquity, is known to have been applied.

During the next few years al-Biruni seems to have visited the Samanid court at Bukhara, as well as the court of the Ispahbad of Gilan. But he was busy collecting the enormous mass of information on the chronology of the ancient nations of Europe and Asia that he dedicated to the Ziyarid prince of Gurgan in 1000 and that in English is known simply as the Chronology. This remains the most significant source for the various Iranian calendars and for much of the history of central Asia.

By 1004 al-Biruni was in Jurjaniya. He became a prominent figure at the Jurjaniya court, being often employed as a diplomat and as a spokesman for the throne. He continued, however, making his astronomical observations under the Shah's patronage.

But the Shah had increasing difficulties with his brother-in-law, Sultan Mahmud of Ghazni. Finally, in 1017 Mahmud conquered Khwarizm and carried off al-Biruni as a prize of war. Al-Biruni was sent to the region near Kabul, where he commenced making observations in 1018. In 1022 and 1026 Mahmud conducted highly successful expeditions into India, and al-Biruni availed himself of the opportunity to learn some Sanskrit (though not as much as is generally thought; he depended heavily on pundits to translate for him), studying especially Indian astronomy, astrology, chronology, and social customs.

Most of his extant works were written in the 1020s and 1030s and reflect his interest in, and growing knowledge of, the Sanskrit astronomical texts current in the Punjab. These include On Shadows (ca. 1021), Tahdid (1025), On Chords (1027), On Transits, India (1031), and Al-Qanun al-Masudi, as well as the Arabic translation of Vijayanandin's Sanskrit Karanatilaka. These are fundamental texts for the history of Islamic and Indian astronomy of the 8th-10th centuries because of al-Biruni's extensive citations of earlier texts; they are also full of reports of al-Biruni's own observations, which are among the best made in the medieval period. He was not always as successful in his calculations.

Till his death soon after 1050 in Afghanistan, al-Biruni continued to write, turning his attention to problems of specific gravity, gemology, pharmacology, and Indian philosophy (the Patanjali), among other subjects. It is not clear when he wrote the Tafhim, his most important work on astrology. In all, the bibliography he himself drew up lists 113 titles, and this list can be expanded to 146; 22 are extant. He was, then, a most prolific author, and throughout his work, all of which is extremely technical, he maintained the highest standards of competence. He well deserved the epithet "Master" bestowed on him by his admiring contemporaries.

Further Reading

Many of al-Biruni's extant writings have not been published. He has been the object of many intensive studies, but the results are scattered among various scholarly journals. Some idea of the range of this scholarship can be gained from the volume issued by the Iran Society of Calcutta on the occasion of the thousandth lunar year since his birth, Al-Biruni Commemoration Volume (1951). See also George Sarton, Introduction to the History of Science, vol. 1 (1927); Eugene A. Myers, Arabic Thought and the Western World in the Golden Age of Islam (1964); and Seyyed Hossein Nasr, An Introduction to Islamic Cosmological Doctrines: Conceptions of Nature and Methods Used for Its Study by the Ikhwan al-Safa, al-Biruni, and Ibn Sina (1964).

Additional Sources

Said, Hakim Mohammad., al-Bairaunai: his times, life and works, Karachi: Hamdard Academy, 1981. □

Al-Biruni (973-1048)

Al-Biruni, born Abu'l-Rayhan Muhammad ibn Ahmad Al-Biruni, an outstanding eleventh-century astrologer whose writings compiled the astrological teachings of several cultures. Al-Biruni was born in Uzbek, a country until recently a part of the former Soviet Union, located just north of Iran and Afghanistan. He grew up under the multicultural influences of Persia, India, and the Greek empire of Alexander. Here Zoroastrian and Manichean teaching mingled with Hinduism and emerging Islam. In the areas of astronomy, mathematics, and astrology, this area of the world, making the transition to Islam, was far ahead of Europe, then only beginning to recover its classical tradition.

As a young man, Al-Biruni began to travel through Persia, Afghanistan, and India and to gather the material for one of his important books, Chronologies of Ancient Nations, detailing the histories of the peoples of the area. It was completed near the end of the century. Around 1010 he settled in his native land for a decade until the ruler (who was also his patron) was overthrown and the nobility was exiled. Al-Biruni then lived in India for an extended time and wrote a volume on the people of the Indus Valley as well as his most remembered text, The Book of Instruction in the Elements of the Art of Astrology, generally called the Tafhim.

The Tafhim, designed as an introductory textbook for the young astrologer, addresses all of the subjects an astrologer would be expected to have mastered, including mathematics, geography, history, and astronomy, all of which are treated before any consideration of astrology. Al-Biruni picked up this learning from the foundational Tetrabiblos of Ptolemy, upon which astrology is built, and he compared Persian astrology with its Hindu counterpart.

The Tafhim was reproduced and widely circulated in Southern Asia and found its way to Europe, where it was read three centuries later by Guido Bonati and influenced his important Liber Astronomie. It was translated into English in 1934 by R. Ramsey Wright.

Sources:

Al-Biruni. The Book of Instruction in the Elements of the Art of Astrology. Trans. R. Ramsey Wright. London: Luzac, 1934.

——. The Chronologies of Ancient Nations. Translated by Edward Sachau. London: W. H. Allen, 1879.

Abu Rayhan al-Biruni

973–1048

Geographer

Sources

The Importance of Geography . One of the greatest Muslim geographers was al-Biruni, who once said, “This subject is an all-important one for travellers and merchants. It is desired by princes and noble personages, sought for by judges and doctors of law, the delight of commoners and men of rank.”

Intellectual Achievements . Born in Khalwarizm, Khorasan (in present-day Turkmenistan), al-Biruni was considered one of the foremost Persian scholars and scientists of his age. Writing in Arabic, he could also speak Turkish, Persian, Sanskrit, Hebrew, and Syriac, and in addition to his geographical works, he wrote on astrology, mathematics, physics, medicine, and history.

Royal Geographer . In 1017 al-Biruni was captured during a war with the sultanate of Ghazna (in Afghanistan) and was made royal geographer to Sultan Mahmud. While traveling with the sultan on military expeditions he became an expert on the peoples, cultures, and physical geography of India, writing Tahqiq al-Hind (Facts About India, circa 1030).

Geographical Writings . In his works on geography al-Biruni discussed the roundness of the Earth and gave latitudes and longitudes of many places. Despite political divisions, Muslim lands represented a vast territory of common culture in which travel and research could take place. As al-Biruni said, “To obtain information concerning places of the earth has now become incomparably easier and safer. Now we find a host of places which in the Ptolemaic Geography are indicated as lying to the east of other places, actually situated to the west of the others named, and vice versa.” Al-Biruni and other Muslim geographers were able to use advances in mathematics such as algebra and trigonometry to determine more accurately the exact locations of places on the Earth and thus revise the latitude and longitude information in their charts.

Sources

D.J. Boilot, “al-Biruni,” in Encyclopedia of Islam, CD-ROM version (Leiden: Brill, 1999).

Ainslie Embree, Alberuni’s India (New York: Norton, 1971).

Seyyed Hossein Nasr, Science & Civilization in Islam, second edition (Cambridge, U.K.: Islamic Texts Society, 1987).

al-Bīrūnī, Abū Rayḥān (973–1049 (AH 362–442)). Muslim scholar of wide-ranging interests, not least in other religions. His study culminated in Kitāb al-Hind (The Book of India). On this basis, he developed work of his own on a wide scale, particularly, but by no means exclusively, in astronomy.