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The Astronomical Observatories of Jai Singh c4.s1: Astronomical Works consulted by Jai Singh

The Astronomical Observatories of Jai Singh c4.s1

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English

Astronomical Works consulted by Jai Singh

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2. Of the works of his predecessors and contemporaries there is evidence that Jai Singh was acquainted with the following: Ptolemy's *Almagest*; the astronomical tables of Ulugh Beg; some Treatises on the Astrolabe; La Hire's *Tabulae Astronomicae*; and Flamsteed's *Historia Cœlestis Britannica*; also certain western mathematical works such as Euclid's *Elements*, a treatise on plane and spherical trigonometry and on the construction of logarithms. This, of course, cannot be an exhaustive list since his valuable library no longer exists entire,¹ and it would be fairly safe to assume that Jai Singh collected and studied all the available astronomical works; indeed it is recorded specifically that he procured from Europe, besides the tables of La Hire, those of earlier dates.

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¹ It is said that Jaggat Singh gave Jai Singh's unrivalled library to a courtesan: it was thus despoiled and its treasures distributed among her "base relatives." This would account for the meagreness of the information now available; but the tale does not altogether bear the impress of truth.

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(i) The book that held sway in Europe for a thousand years after its publication and among the Arabs for a thousand years after its translation was Ptolemy's *Almagest*. No other text-book that has ever been written had such a reputation. Jai Singh himself speaks of Ptolemy as one of the greatest astronomers, and one of his most important acts was to order a translation from the Arabic of Ptolemy's great work. This translation, apart from its intrinsic value, has a somewhat special interest: its title *Samrāṭ Siddhānta* 'the supreme text-book' has practically the same meaning as the Arabic title *Al-Majiṣṭī* 'the greatest' and as the Greek title *μεγάλη σύνταξις* 'the great compilation.'²

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² Another title is *Siddhānta Sāra Kaustubha*. See AUFRECHT, Cat. Sans. Man. Trin. Coll., Dublin, p. 75.

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According to Garrett,³ the *Samrāṭ Siddhānta* expresses Jai Singh's views on astronomy, and this, probably, is quite true; but the implication that it was an original work composed by or for Jai Singh is wrong. It was written by Jagannāth, one of Jai Singh's assistants, who was quite unambiguous on its origin. He wrote:

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³ The Jaipur Observatory and its Builder. By L'eutenant A. ff. Garrett, R.E., assisted by Pandit Chandradhar Guleri. 1902, pp. 19 and 21.

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Grantham siddhānta samrājaṃ samrāṭ rachayati sphuṭam |
Tuṣṭtyai Śrījayasimhasya Jagannāthāhvayaḥ kṛti ||
Arabī bhāṣayā grantho Mijāstīnāmakaḥ sthitaḥ |
Gaṇakānāṃ subodhāya gīrvāṇya prakṭi kṛtaḥ ||

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Jagannāth's introduction contains, besides the usual invocation, (a) eulogies of Jai Singh, with which are references to certain events of some importance,⁴ (b) a list of instruments and (c) an explanation of the source from which the work was obtained.

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⁴ The Govind image episode, the Vāja Peya sacrifice, and the abolition of a certain tax (? the Jizeya).

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Jai Singh, Jagannāth says, was clever in exhibiting the new methods with globes and other instruments; and that, with the help of certain learned mathematicians and astronomers, he had made observations of the stars. The instruments proper to an observatory are said to be (1) Nāḍī Yantra (sun-dial), (2) Gola Yantra (Sphere), (3) Digaṁśa Yantra (Azimuth instrument), (4) Dakhshiṇo Digbhitt (Mural quadrant), (5) Vṛitta Shashtāṁśaka (An arc of sixty degrees placed in the meridian) which, he says, "the yavanas call *shadsafkari*," (6) Samrāṭ Yantra (Supreme instrument—an equinoctial dial), 'the best among the instruments,' and (7) Jaya Prakāś 'the crest jewel of all instruments.'

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Then we are told (in the verse quoted in full above) that Jagannāth prepared this excellent *Siddhānta Samrāj* for the delight of Jai Singh, and that it is a rendering into Sanskrit for the benefit of mathematicians of a work in the Arabic language entitled *Mijāsti*.¹ He also tells us² that "in the Yavana country, the Yavana masters of astronomy, Abarkhas, etc., found the maximum declination to be 23 degrees 51 minutes 19 seconds; and that in Yunan, 36 degrees north, it was found to be 23 degrees 51 minutes 15 seconds by the observations of Vitlamayus. Ulugh Beg found it to be 23 degrees 30 minutes 17 seconds at Samarqand, 39 degrees 17 minutes north. By observation with this instrument we found it to be 23 degrees at Indraprastha in 1651 Sālivāhana."

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¹ *i.e.*, Ptolemy's *Almagest*.

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² From the Calcutta MS. The names are somewhat puzzling, but Abarkhas is for Hipparchus, Vitlamayus is for Ptolemæus. By Yunan possibly Rhodes is meant. The date, 1651 Sālivāhana is equivalent to A.D. 1729. Indraprastha is Delhi.

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(ii) Ulugh Beg's astronomical tables were completed in A.D. 1436 and became almost as famous as those of Ptolemy, and they formed the basis of most subsequent catalogues. Flamsteed used them and so did Jai Singh, who brought them up to date. For details as to the use made by Jai Singh of Ulugh Beg's tables see below (p. 8).

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(iii) The Hindu name for the astrolabe is *Yantra Rāja* and Garrett says³ that this "appears to be a very ancient type of instrument of Hindu origin," and also that "it appears to have been held in great esteem by Jai Singh as he himself wrote a book concerning its construction and use." As a matter of fact, the astrolabe or *Yantra Rāja* is not of Hindu origin at all. The earliest Hindu work on this instrument is of the fourteenth century of our era, while numerous Arabic and Persian works dating from the tenth century onwards are known. The earliest Hindu work known is by Mahendra Sūri and was written in the time of Firoz Shah in Śaka 1292 or A.D. 1370,⁴ and there are indications that it was used by Jai Singh. But Jai Singh did not rely on this work alone and certainly used some of the Arabic or Persian text-books on the astrolabes, of which there were a great many available.

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³ p. 49. See R. Mitra *Cat. Sans. MSS., Bikaner*, p. 351.

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⁴ This work together with Malayendu's commentary was printed by the late Pandit Sudhākar Dvivedi of Benares. In the India Office Library is a manuscript (2905, 1528a) of this work which was described by Eggeling (*Catalogue Sanskrit Manuscripts, India Office Library*, V. p. 1030. See also No. 2906 (2343 b, p. 1031) as follows:— " *Yantra rāja* or *Yantrarājāgama*, also called *Suyantrāgama* and *Sadyantra*, a treatise in five chapter on the construction and use of the armillary sphere and the calculation of celestial and terrestrial longitudes and latitudes, by Sūri Mahendra, the pupil of Madana Sūri, the court astrologer of Bhrigapura."

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Mahendra describes his treatise as "This scientific work, the good Yantra Rāja, full of much variety and wonder causing, for the benefit of the people, etc." It is "abridged, essence-like, exhaustive but very simple and delightful to the heart." He says (v. 3): "Many Yavanas have also composed scientific works on this instrument in their own language and according to their own particular understanding" and, he continues, "having found them like oceans, I now compose this work, like nectar, as the essence of them all." He gives a list of thirty-two stars¹ and then (v. 28) writes: "After freeing these stars of drik karma mark them on the celestial globe This is a secret that has come from the Yavanas."

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¹ Mahendra's list is given in Appendix A. He gives the rate of precession as 54 seconds, and it may be noted that 18° 53′ / 54 secs. p.a. gives almost exactly 1259 years, and this gives the date for Ptolemy's catalogue as A.D. 111 approximately.

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Mahendra's small star catalogue is of considerable interest because such lists are very uncommon in Hindu books and because it is taken from Ptolemy's catalogue. The latitudes are exactly the same as Ptolemy's in all cases but one, and the longitudes differ by exactly 18° 53′ in all cases but six.

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(iv) Jai Singh himself refers to La Hire's tables (see page 14) and to other European tables, and in the palace library at Jaipur is still a copy of Flamsteed's great work.

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P. de la Hire was a French scholar of repute who lived from A.D. 1640 to 1718. He wrote many mathematical works and in 1702 published his Tabulae Astronomicae of which the first part had appeared in 1687. This work contained, besides the usual tables, a refraction table (which it is said Jai Singh copied) and a description of a machine invented by la Hire to show the theory of eclipses. Another of la Hire's works was 'La Gnomonique ou l'art de tracer des cadrans ou horologes solaires sur toutes sortes de surfaces, par differentes pratiques, avec les démonstrations géometriques de toutes les operations.' This was published in 1682 and would have been useful to Jai Singh.

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(v) John Flamsteed lived from 1646 to 1720. His Historia Cœlestis Britannica appeared in 1712, in one folio volume, made up of two books, the first containing the catalogue of stars and sextant observations; the second, observations with Sharp's mural arc. The complete work, consisting of three folio volumes, was published in 1725. Flamsteed himself lived only long enough to finish the second of the three volumes. The third was edited by his assistants Crossthwaite and Sharp. It contains descriptions of the instruments used by Tycho Brahe, Hevelius, Flamsteed himself, etc.; the star catalogues of Ptolemy, Ulugh Beg, Tycho Brahe, the Landgrave of Hesse and Hevelius, and, finally, the British catalogue of 2,935 stars.

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(vi) Undoubtedly Jai Singh possessed other astronomical works, but the only possible hints as to their identity are contained in the preface to his own catalogue where he mentions several astronomers by name. For example, he he not only mentions Naṣīr-al-Dīn al-Ṭūsī (born A.D. 1201) but also his commentator (Ali b. M.) al-Gurgānī. Naṣīr-al-Dīn was one of the greatest Muslim astronomers.

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He made observations at the Marāgha observatory and published the famous ‘Ilkhānic Tables.’ He wrote numerous works on astronomy and mathematics, including commentaries on the works of Archimedes, Euclid, Ptolemy, etc.

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Coupled with Naṣīr al-Dīn, Jai Singh mentions also Jamshīd Kāshi (Jamshīd b. Mas‘ūd b. M. Gijāt al-Dīn al-Kāshī), who was one of Ulugh Beg’s assistants. He wrote several works on astronomy and particularly on the Khāqānī tables. He also mentions al-Ṣūfī (see page 10).

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(vii) Hunter¹ tells us that he met at Ujjain a grandson of Jai Singh’s principal assistant (? Jagannāth). “In his possession,” he writes, “I saw the translation into Sanskrit of several European works, executed under the orders of Jaisingha, particularly Euclid’s *Elements*² with a treatise on plane and spherical trigonometry, and on the construction and use of logarithms which was attached to Cum’s and Commandine’s edition. In this translation the inventor is called Don Juan Napier³ . . . . Besides these the Pandit had a table of logarithms of logarithmic sines and tangents to seven places of figures, and a treatise on conic sections.”

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¹ Some account of the Astronomical Labours of Jaya Sinha, Rajah of Ambhere, or Jayanagar. By W. Hunter. *Asiatic Researches*, Vol. V., 1799, p. 209.

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² This is the *Rekhaganita* referred to on p. 69.

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³ This seems to be the source of Tod’s statement that Jai Singh caused “Don Juan Napier on the construction and use of logarithms to be translated into Sanskrit.” (ii. 358).

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We are also told that “maps and globes of the Feringhees were obtained from Surat.”⁴

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⁴ Garrett p. 20. In the Jaipur museum there is a terrestrial globe attributed to Jai Singh; and for the transference of Ulugh Beg’s co-ordinates into declination and right ascension a large and fairly accurate celestial globe was used by Jai Singh’s assistants (see p. 8).

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