Khuda Bakhsh Library

Close to the banks of the Ganges, in Patna, stands the Khuda Bakhsh Oriental Public Library a unique repository of about 21,000 Oriental manuscripts and 2.5 lakh printed books. Though founded earlier, it was opened for public in October, 1891 by the illustrious son of Bihar M. Khuda Bakhsh Khan with 4,000 manuscripts, of which he inherited 1,400 from his father M. M. Bakhsh.

The copy available at the Khuda-Baksh Library is the only extant copy. A note on the text says that it has been compared with the Original, but we are not sure about the fate of the “original” copy mentioned in that context.

At the invitation of the Khuda-Bakhsh Library, I gave the following speech at April 14^th 2004. Dr Daisy Narain, Dept. of History, Patna ???? college presided.

Dr Gopal Kamal, Dr Daisy Narain,
Mr President, Dr Imatiz Ahmad, Ladies and gentlemen!

I wish to thank Dr Imtiaz Ahmad, for his kind proposition to speak about a short treatise of Bīrūnī who was at once a versatile contributor to the science of his own day and a matchless critic and historian of the scientific lore of his predecessors. He was able to use many sources which have since disappeared, and his writings afford us part of the means for eventually tracing the transmission of astronomical theory between Babylon, India and Persia.

Invitation in Hindi

(Click to enlarge)

This treatise is in Arabic, and is called تمهدُالمتقر لتحقیق معنی الممرّ and is about the varieties of transit in astronomy and astrology. The unique extant manuscript copy the original text belongs to the Khuda-Bakhsh Oriental Public Library, Patna. It was published in 1948, by the Osmania Oriental Publications, Heydarabad, together with three other treatises, under the title رسائل البیرونی. Since this treatise is a veritable mine of numerical parameters, and cites a number of quotations from lost works, especially from the Sasanian set of astronomical tables, I decided to come to Patna, and consult directly the manuscript.

Meanwhile, I observed that there exists a collection of Avestan Pahlavi and Pazand fragments and texts in your library. I have not yet thoroughly examined the collection; however, it is manifest that some of them are notably important. For example, the Pahlavi A.J. (“the memoir of J. the wise”). The only known manuscript copy of the A.J. belongs to the State Library of Munich, and has been edited by the Italian scholar Giusippe Messina. But the ms. of Munich is corrupt, and Messina’s edition full of errors. Now, by the help of the second ms. Copy belonging to your library, it is possible to prepare a critical edition of that important text. [1]

Invitation in Urdu

(Click to enlarge)

Let us come back to the treatise of Bīrūnī. As its title indicates, it is to the explanation of the usages of the ممرّ that he has devoted this treatise. The Arabic word ممرّ “crossing”, has the standard technical meaning converged by the modern term “meridian transit”. In this treatise Bīrūnī uses the same word in a number of more general senses. He begins by setting up three cosmic dimensions: longitude, latitude, and thickness.

The first dimension appertains to displacements more or less east or west with respect to a terrestrial observer. The second dimension is measured north and south. The third dimension involves motions normal to both the first two, that is, along the radius vector from the earth’s centre to the celestial object in question. With each of these dimensions one or more varieties of transit is associated.

The techniques that Bīrūnī describes seem to have been worked out in the context of a planetary theory different from that of Ptolemy. In fact, he refers to and partly compares three different schools: Greek, Indian, and Persian. This shows that, he follows the older tradition of the astronomers in the Sasanian period. According to the DD, these astronomers used three kinds of Zīg [2]: zīg hindūgān (the Indian set of A.T.), zīg ī hrōmīgān (the Greek set of A.T.), and zīg ī šahryāran (the royal set of A.T.). These royal tables are known to us only from citations in Arabic treatises. These documents are scarce and corrupt. The job is made both frustrating and fascinating by the fact that no astronomical documents in Pahlavi have survived; often the student can judge only from internal evidence whether a particular comes from a Sasanian source, or whether it originated in a later period. We can distinguish three sets of Royal Tables:

The first set of Royal Tables was composed in the early Sasanian period. The first two sasanian rulers (Ardašēr and Šābuhr) sponsored Pahlavi translations of Greek and Sanskrit works on astronomy and astrology. Among the texts so translated were the Greek astrological treatises of Dorotheus of Sidon and Vettius Valens, and the astronomical Syntaxis mathemike (meγistīg, المجلسی) of Ptolemy, as well as a Skt. astrological work written by one Faramāsb (parameshvara?).

The second was composed in 556, under Xusrō Anušeravān. This version of the Royal Tables was used by ماشاءالله in his کتاب فی القیرات والادیان والملل written about 810; from this we can see that it rejected the Indian method of finding the mean longitudes of the planets by means of their integer rotations in a yuga (“world period”) [3].

The last set of Royal Tables was written under Yazdegird III in the 630’s (or 640’s) and was translated into Arabic by تمیمی ; we have only fragments of this translation. According to الهاشمی :

Yazdgird brought out a zīg and he named it after the example of the Šāh (Xusrō). He made it in three kardajas and called it “The Triple”. Its explanatory text and apogees and nodes and mean motions and equations correspond to those of the [Indian] Arkand as to midnight epoch. People still work with it, except that they regard the heavy ones (the superior planets) more correct in the Arkand by observation, and the light ones more correct in the Šāh.

One characteristic that differentiates one set of tables from the other is the choice of the zero meridian. In the Indian tables, the zero meridian was in the middle of the inhabited world, on the equator, called Lanika, translated into Arabic قبةالأرض ; however, the Indian astronomers calculated longitudes from Ujjain. In the Greek tables, the zero meridian was supposed to be the farthest western point of the equator in the inhabited world, translated into Arabic الجزائر السعادة , الجزائر الخادة [4]. And finally, in the Persian Tables, the z.m. was placed on the farthest eastern point of the equator, called کنکدز .

To understand the historical connection of these three tables, an introductory remark is necessary.

From the very beginnings of science the objects in the Solar System have stimulated fruitful curiosity, causing men to invent abstract models to enable them to predict the positions and motions of the Sun and the planets. The Earth rotates about the Sun in an orbit which is almost a circle. If the Earth is thought of as stationary, then it is the Sun which rotates about us, carrying with its satellite planets. For an inferior planet, one whose orbit is smaller than the Earth’s (or of the Sun’s), its resultant motion with respect to the Earth is easy to visualize. It is the motion of a point on a wheel rotating independently at the same time that the wheel’s centre rotates upon the rim of a larger wheel. To adopt ancient terminology, the larger orbit is the deferent, the smaller the epicycle. The case of a superior planet is somewhat more involved, since its orbit is larger than the Sun’s. But the two orbits can be interchanged without affecting the position of the planet, to retain the deferent as the larger with the centre in the vicinity of the Earth, and the epicycle as the smaller, outer wheel carrying the planet. Under all circumstances, then, the planet moves with respect to the Earth in a series of loops congruent, in insufficiently precise for anything, but a good approximation. With an actual planet, the size and character of the retrogradations vary, depending upon the region of the sky in which they take place.

Having set up the problem, it is useful to note the three ways by which, in various places and times, it was solved:

 First — Purely numerical techniques may be used, with no appeal, at any stage, to a geometric model. This highly sophisticated approach was developed by Babylonian astronomers in the late Achaemenian and Parthian period; it the disappeared, until the clay tablets on which it was recorded were excavated and deciphered in recent times. After the new examination of the PS of VM, is found there also an evidence of the pure numerical techniques. Between the Babylonian tablets and the Skt. treatise, there is a distance of many centuries, and there is no testimony from the intermediary period.

 Second — The simple deferent-epicycle model may be accepted, and the necessary variation in the retrogradations introduced by means of computation schemes which have no immediate geometric motivation or rationale. Unlike the first way, these procedures involve trigonometric, rather than algebraic, transformations because of the implicit presence of the epicycle. They were characteristic of Indian and Persian-Sasanian astronomy.

 Third — The deferent-epicycle configuration may be modified geometrically, by making the Earth eccentric with respect to the deferent and by introducing a periodic variation in the speed of the epicycle centre, in order to improve the correspondence between the model and the facts. This is the method of Ptolemy, and his solution is about as good a job as can be hoped for without abandonment of circular orbits. As with other ways, the ultimate result is numerical, a set of true longitudes corresponding to given instants.

Apart from the common astronomical procedures, the Indian and Persian astronomers shared common mythological elements. Bīrūnī states thus:

The Persian astronomers call what relates to the heaven of the apogee (/the deferent) gōy and they say that the planet is ascending in thegōy or descending in it. And they call whar relates in this matter to the epicycle a zē (that means “chord”) for the epicycle to the mythical cords attached to the planets, and states thus: “This is the opinion of the ancients regarding the bonds of the planets with Sun and their retrogradation from the tension of the cord tightened by it, and its forward motion by its slackening.”

In fact, this idea goes back to the Vedas. In the Upanishad it is said:

O Gautama, the lights are bound to Vāyu, everything are bound to Vāyu.

The word for the bond (of Vāyu) is raśman. [5]

We find and elaborate doctrine of “the bond of wind” for the explanation of the etrogradations of the planets in the Purānas, which was used by the Indian astronomers. For example, in the beginning of the Surya-Siddhānta or in the 13^th chapter of the PS.

The same idea exists in the Pahlavi Bundahišn: the planets are bound by the “immaterial bond” (bann ī menōgig) or by the “bond of wind” (bann ī vād). As Bīrūnī confirms in his short treatise, the Persian astronomers incorporated it in the Royal set of astronomical tables.

Well, these were some rudimentary words that I could say about treatise of Bīrūnī. Thanks for your attention and patience.