The Astronomical Observatories of Jai Singh c5: Chapter II.—Jai Singh's Astronomical Tables
The Astronomical Observatories of Jai Singh c5
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Chapter II.—Jai Singh's Astronomical Tables
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4. The *Zīj Muḥammad Shāhī* is a set of astronomical tables prepared under the direction of Jai Singh and named after the Emperor, Muḥammad Shāh.¹ Of this work, I found (A) an incomplete Devanāgarī manuscript at Jaipur, and (B) a complete Persian manuscript at the British museum. At first, B was supposed to be an original work, while A was said to be, not the *Zīj Muḥammad Shāhī* itself but *Ulugh Beg's* celebrated catalogue brought up to date by Jai Singh and his assistants.
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¹ Hunter and others say that Jai Singh was chosen by Muḥammad Shāh to reform the calendar, but probably Jai Singh was the mover and at the most obtained the Emperor's formal sanction.
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5. (A) The Jaipur manuscript begins as follows:—
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“Homage to holy Ganesh. Catalogue of 48 constellations. From the time of Ulugh Beg's table A.H. 841 to the present date A.H. 1138² or 297 years the mean motion³ is 4 degrees 8 minutes. In the *Zīj Muḥammad Shāhī* the estimates of declination, etc., are taken from the globe. Right ascension divided by six is apparent time.”
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² A.H. 841=A.D. 1437-8; A.H. 1138=A.D. 1725-6; and 297 Muslim years=288·2 Christian years. [622 - A. H./100 = A.D. - A.H.]
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³ The precession of the equinoxes is meant. The rate here given, 4° 8' in 297 Muslim years, is equivalent to 51·6" a year. See appendix D.
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Two pages of the Jaipur manuscripts are shown in Plate I (Figures 1, 2), and I give below extracts⁴ from the manuscripts together with a table of comparisons. The manuscript gives: (*a*) The numbers of the constellations and star numbers, and these in all cases follow Ulugh Beg's order exactly. (*b*) The nomenclature, which is a translation from Ptolemy (through Ulugh Beg). In a few cases the Persian and Hindu names are also given. (*c*) Ulugh Beg's longitudes with 4°8' added for precession. (*d*) The latitude which in practically all cases is the same as Ulugh Beg's. (*e*) The so-called polar longitudes⁵ (what Delambre calls ‘false longitudes’); this is the *Sūrya Siddhānta* method of indicating the positions of stars, but it also occurs in Muslim works, e.g., Abū ‘Alī al-Ḥasan in the 13th century of our era calculates the polar longitudes for a number of stars; and the presence of these polar longitudes in Jai Singh's catalogue is possibly due to Muslim and not Hindu influence. (*f*) Declinations, and (*g*) Right ascensions apparently read off from a globe. (*h*) Right ascension in *ghaṭis* and *palas* obtained from (*g*) by dividing by six.⁶ (*h*) Star magnitudes which seldom differ from those recorded by Ulugh Beg.
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⁴ Further extracts are given in appendix A.
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⁵ The polar longitude is marked on the ecliptic by the circles of declination, that is, the difference (Δλ) between the true longitude (λ) and polar longitude (λ') is that portion of the ecliptic intercepted between the star's declination and latitude circles. The polar latitude β' (which is not given in the MS.) is, similarly, the part of the declination circle between the star and the ecliptic. The change of co-ordinates can be made by help of the following formulæ (i) tan M = cos ω / cos λ (ii) sin λ' = sin M. sin χ (iii) sin Δλ = tan λ cot M.
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⁶ 60 palas = 1 ghati = 24 minutes = 6 degrees.
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The catalogue is not an original one, but is Ulugh Beg's brought up to date.
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Fig 1
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Fig 2
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Fig 3
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Fig 4
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Figs 1 & 4 FROM MANUSCRIPT OF STAR CATALOGUE. Figs 2 & 3 FROM MANUSCRIPT OF SAMRAT SIDDHANTA.
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The page provided is blank.
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The method of transference of co-ordinates employed was bound to lead to errors of certain types, viz., errors due to the graduations of the globe employed, and a greater apparent error in northern latitudes. The table has a special interest of its own and an interest in connection with Jai Singh's work as showing at least one of the sources of his astronomical knowledge.
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EXTRACT FROM THE JAIPUR CATALOGUE.
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| A | B | C | D | E | F | G | H | I |
| | | Longitude. | Latitude. | Polar Longitude. | Declination. | Right Degrees. | Ascension in ghatis and palas. | Magnitude. |
| | | ° ' " | ° ' | ° ' " | ° ' | ° ' | g. p. | |
| VI | *Constellation of the Crown.* | | | | | | | |
| 1 | Very brilliant . | 7 8 38 | +40 30 | 7 24 0 | +28 0 | 231 0 | 38 30 | 2 |
| 2 | Beyond this . | 7 5 48 | +46 24 | 7 22 0 | +30 15 | 229 5 | 38 11 | 4 |
| 3 | Above the second to the north. | 7 5 18 | +48 21 | 7 22 40 | +32 5 | 229 50 | 38 18 | 4 |
| 4 | The third to the north of this. | 7 7 48 | +50 45 | 7 26 0 | +33 15 | 233 15 | 38 53 | 6 |
| 5 | Near to the large star to the south. | 7 10 26 | +44 27 | 7 25 0 | +27 0 | 232 15 | 38 43 | 4 |
| 6 | Near this a little to the north. | 7 12 54 | +44 42 | 7 26 30 | +27 0 | 233 50 | 38 58 | 4 |
| 7 | Near to this the sixth to the south. | 7 15 3 | +46 0 | 7 28 30 | +28 0 | 236 0 | 39 20 | 4 |
| 8 | Near to number 7 | 7 14 39 | +49 30 | 8 0 0 | 31 0 | 237 30 | 39 35 | 4 |
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| | From Ptolemy. | Modern name. | FROM ULUCH BEG. | DIFFERENCE BETWEEN MS. AND ULUCH BEG. | DIFFERENCE BETWEEN MS. AND FLAMSTEED REDUCED TO A.D. 1725. |
| | | | I | Longitude. | Latitude. | Δ long. | Δ lat. | Δ long. | Δ lat. |
| VI | *Corona Borealis.* | | | ° ' | ° ' | | | | |
| 1 | Fulgens earum quæ sunt in corona. . | 5 α | 7 4 34 | +44° 30' | +4° 4' | +0 | +18' 6" | -3°51'18" |
| 2 | Quæ omnes istas præcedit . . | 3 β | 7 1 40 | +46 24 | +4°8' | 0 | +31'57" | +19'19" |
| 3 | Borealior quæ istam sequitur. . | 4 θ | 7 1 10 | +48 21 | +4°8' | 0 | -17'30" | -13'51" |
| 4 | Sequens istam et borealior ista . | 9 π | 7 3 40 | +50 45 | +4°8' | 0 | -32'51" | +14'56" |
| 5 | Quæ fulgentem a meridie sequitur. | 8 γ | 7 6 28 | +44 27 | +3°58' | 0 | -35'51" | -5'19" |
| 6 | Quæ istam proprius sequitur. . | 10 σ | 7 8 46 | +44 42 | +4°8' | 0 | -14'24" | -11'6" |
| 7 | Quæ post istas rursus sequitur . | 13 ε | 7 10 55 | +46 0 | +4°8' | 0 | -13'25" | -6'28" |
| 8 | Sequens cunctas quæ in corona sunt . | 14 ι | 7 11 31 | +49 30 | +38' | 0 | -30'48" | +18'38" |
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6 (B). The British Museum manuscript¹ bears the title *Zīj Jadīd Muḥammad Shāhī* (the new Muḥammad Shāh tables) and Rāja Jai Singh Sawāī is indicated as the author. The work consists of three books: (i.) On the current eras, namely, the Hijrah, the eras of Muḥammad Shāh, the Christian era, and the Samvat era. (ii.) On the determination of the ascendants. (iii.) On the motions of the planets and stars and their positions.
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¹ Rieu's Catalogue of Oriental MSS. "Add. 14373. Foll. 222; 11¼ inches by 7½; 12 lines, 4¾ inches long; written in Nastālik, with Unvan and gold ruled margins, apparently in the 18th Century (Francis Gladwin)." The MS. is in good condition and could easily be reproduced by rotograph.
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The first two sections follow Ulugh Beg and the third section is simply Ulugh Beg brought up to date. The catalogue of stars is headed: "Table showing the positions of the fixed stars as determined at the Samarqand observatory." The catalogue gives (*a*) serial numbers, (*b*) constellation numbers, (*c*) names of constellations and stars, (*d*) Longitudes, (*e*) Latitudes, (*f*) Directions, (*g*) Magnitudes according to Ptolemy, (*h*) Magnitudes according to Ṣūfī.² The total number of stars given is 1018 (Ulugh Beg's number) and these are arranged in identically the same order as those of Ulugh Beg. The latitudes are the same as Ulugh Beg's and the longitudes differ by 4° 8', as in the case of the Jaipur MS.
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² 'Abd-ul-Raḥmān b. 'Omar, Abū'l-Ḥusain, al-Ṣūfī (died A.D. 986) wrote on the fixed stars, the astrolabe &c. (H. Suter, Die Math. u. Astr. d. Arabes, p. 62).
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7. The preface to the *Zīj Muḥammad Shāhī* is, from an historical point of view, perhaps the most interesting part and is here given in full.³
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³ Hunter, As. Res. V. p. 178 f.
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Praise be to God, such that the minutely discerning genius of the profoundest geometers in uttering the smallest particle of it, may open the mouth in confession of inability; and such adoration, that the study and accuracy of astronomers who measure the heavens, on the first step towards expressing it may acknowledge their astonishment and utter insufficiency. Let us devote ourselves at the altar of the King of Kings—hallowed be his name—in the book of the register of whose power the lofty orbs of heaven are only a few leaves; and the stars and that heavenly courser the sun, a small piece of money in the treasury of the empire of the Most High. If he had not adorned the pages of the table of the climates of the earth with the lines of rivers, and the characters of grasses and trees, no calculator could have constructed the almanac of the various kinds of seeds and of fruit which it contains. And if he had not enlightened the dark path of the elements with the torches of the fixed stars, the planets and the resplendent sun and moon, how could it have been possible to arrive at the end of our wishes, or to escape from the labyrinth and the precipices of ignorance.
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From inability to comprehend the all encompassing beneficence of His power. Hipparchus is an ignorant clown, who wrings the hands of vexation; and in the contemplation of His Exalted Majesty,
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PTOLEMY is a bat, who can never arrive at the sun of truth: the demonstrations of EUCLID are an imperfect sketch of the forms of his contrivance; and thousands of JAMSHĪD KĀSHĪ,¹ or NAṢĪR ṬŪSĪ,² in this attempt would labour in vain.
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¹ Jamshīd b. Mas'ūd Gijāt al-Dīn al-Kāshi was one of Ulugh Beg's astronomers.
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² Naṣīr al-Dīn al-Ṭūsi was born A.D. 1201. He worked at the Marāgha observatory and published the famous 'Ilkhānic Tables.' He translated Euclid's *Elements* and Ptolemy's *Almagest*, and wrote many works on astronomy.
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But since the well-wisher of the works of creation and the admiring spectator of the theatre of infinite wisdom and providence SAWĀĪ JAI SINGH,³ from the first dawning of reason in his mind and during its progress towards maturity, was entirely devoted to the study of mathematical science, and the bent of his mind was constantly directed to the solution of its most difficult problems: by the aid of the Supreme Artificer he obtained a thorough knowledge of its principle and rules.
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³ Jai Singh writes in the third person.
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He found that the calculation of the places of the stars as obtained from the tables in common use, such as the new tables of SA'ĪD GURGĀNĪ⁴ and KHĀQĀNĪ, and the *Tasahīlāt-Mula Chānd*⁵ *Akbar Shāhī*,⁶ and the Hindu books, and the European tables,⁷ in very many cases give them widely different from those determined by observation: especially in the appearance of the new moons, the computation does not agree with observation."
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⁴ Possibly 'Ali b. M. al-Saijid al-Sarif al-Gurgāni, who lived from A.D. 1339 to 1414 in Shirāz, and wrote a commentary on Naṣīr al-ūsi's *Tadkira* (See H. Suter's *Die Mathematiker und Astronomen der Araber und Ihre Werke*, p. 172); but Gurgāni was a designation of Ulugh Beg's family, and Ulugh Beg's tables were sometimes termed the Gurgāni canon [See L.P.E.A. Sédillot's *Prolégomènes des Tables astronomiques d'Oloug Beg*, p.c. xix; also *Ain-i-Akbari*, (iii) 20 and 41 (Jarrett's edition); *Akbarnāma*, (i), 204 (Beveridge's Edition).]
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⁵ Suter (p. 95) mentions one al-Khāqāri, an astronomer and astrologer, who died in A.D. 1038 and who worked at improving the astronomical tables. The Khāqāni tables were supplementary to the Ilkhānic tables of Naṣīr al-Ṭūsi and were prepared and edited by Jamshīd al-Kāshi.
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⁶ "Maulānā Chānd, the astrologer, who was possessed of great acuteness and thorough dexterity in the science of the astrolabe, in the scrutinising of astronomical tables, the construction of almanacs and the interpretation of the stars, was deputed to be in attendance at the portals of the cupola of chastity in order that he might observe the happy time and ascertain exactly the period of birth (of Akbar). He reported in writing to the exalted camp that according to altitudes taken by the Greek Astrolabe and by calculations based on the Gurgāni tables, etc." (*Akbarnāma*, Vol. I, 69-70, Ed. Beveridge). He also cast the horoscope of Jahāngīr in A.D. 1570 according to the Greek canon (ib. ii, 506-7. See also i, 56 and 374).
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⁷ He is possibly referring to La Hire's *Tabulæ Astronomicæ* and Flamsteed's *Historia Cœlestis Britannica*.
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Seeing that very important affairs both regarding religion and the administration of empire depend upon these; and that in the time of the rising and setting of the planets, and the seasons of eclipses of the sun and moon, many considerable disagreements of a similar nature were found—he represented it to his Majesty of dignity and power, the sun of the firmament of felicity and dominion, the splendour of the forehead of imperial magnificence, the unrivalled pearl of the sea of sovereignty, the incomparably brightest star of the heaven of empire, whose standard is the sun, whose retinue the moon, whose lance is Mars and his pen like Mercury with attendants like Venus, whose threshold is the sky, whose signet is Jupiter, whose sentinel Saturn—the Emperor descended from a long race of kings, an Alexander in dignity, the shadow of God, the victorious king MUḤAMMĀD SHĀH¹: May he ever be triumphant in battle.²
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¹ Muḥammad Shāh reigned from 1719-1748.
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² This must have been written before 1739 when Nadir Shāh sacked Delhi.
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He was pleased to reply, since you, who are learned in the mysteries of science, have a perfect knowledge of this matter, having assembled the astronomers and geometricians of the faith of Islām, and the Brahmans and Pandits,³ and the astronomers of Europe, and having prepared all the apparatus of an observatory, do you so labour for the ascertaining of the point in question, that the disagreement between the calculated times of those phenomena, and the times which they are observed to happen, may be rectified.
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Although this was a mighty task, which during a long period of time none of the powerful Rajas had prosecuted; nor among the tribes of Islām, since the time of the martyr prince, whose sins are forgiven,³ MIRZA ULUGH BEG, to the present, which comprehends a period of more than three hundred years,⁴ had any one of the kings possessed of power and dignity turned his attention to this object. Yet to accomplish the exalted command he had received, he bound the girdle of resolution about the loins of his soul and constructed here⁵ several of the instruments of an observatory, such as had been erected at Samarqand,⁶ agreeable to the Mussalman books,⁷ such as Zāt al-Ḥalqa⁸ of brass, in diameter three gaz⁹ of the measure now in use and Zāt al-Sha'batain¹⁰ and Zāt al-Zaqatain and Sads¹¹ Fakhri and Shāmalar.¹²
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³ These seem to be curious expressions for a Hindu to use.
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⁴ Ulugh Beg was assassinated in A.D. 1449 while the Zij Muḥammad Shāhi is supposed to have been published in 1728, approximately 297 Muslim years after. See p. 8.
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⁵ At Delhi.
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⁶ We have very little information about the observatory at Samarqand. Greaves stated that the quadrant used by Ulugh Beg was as high as the summit of St. Sophia at Constantinople, or about 180 feet. The earlier Muslim astronomers had also devised huge instruments. In A.D. 995 Abu-l-Wafā used a quadrant of radius 21 feet 8 inches; al-Khojendi used a sextant with radius 57 feet 9 inches. Naṣir al-Din set himself the task of perfecting instruments, etc. See Sédillot's Prolégomènes des Tables astronomiques d'Ouloug-Beg, p. cxxix. See also page 81 for a fuller account of Muslim instruments.
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⁷ See below for a bibliography of books on the astrolabe. There were numerous Arabic and Persian works on astronomical instruments available.
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⁸ A ring instrument, armilla, sphæra armillaris—(Nallino ii. 329).
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⁹ 3 gaz=9 feet ordinarily, but perhaps here a gaz=1 danda=6 feet approximately.
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¹⁰ An astrolabe with two rings or parts. It is the triquetrum or regulae parallacticae. Al-Battāni calls it the 'long alhidade' (Nallino i. 321). In Leiden is a MS. De ratione qua ope instrumenti Zat al-Sho'batain, etc., by the celebrated al-Kindi. Muḥammad bin Isḥāq b. Abi 'Abbād, Abu'l Ḥasan also wrote on the same instrument (Suter, pp. 25 and 48).
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¹¹ This must be the same as the Shashtāmśa Yantra, which, according to Jagannāth, "the Yavanar called shudzufkari." See pages 3 and 39.
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¹² The Jai Prakāś is called shamlah by Hunter.
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But finding that brass instruments did not come up to the ideas which he had formed of accuracy, because of the smallness of their size,¹ the want of division into minutes, the shaking and wearing of their axes, the displacement of the centres of the circles, and the shifting of the planes of the instruments, he concluded that the reason why the determinations of the ancients, such as HIPPARCHUS and PTOLEMY, proved inaccurate, must have been of this kind. Therefore he constructed in Dār al-Khilāfat Shāh Jahānābād,² which is the seat of empire and prosperity, instruments of his own invention, such as *Jai Prakas* and *Rām Yantra* and *Samrāt Yantra*,³ the semi-diameter of which is of eighteen cubits and one minute on it is a barley corn and a half⁴—of stone and lime of perfect stability, with attention to the rules of geometry and adjustment to the meridian and to the latitude of the place, and with care in the measuring and fixing of them, so that the inaccuracies from the shaking of the circles and the wearing of their axes and displacement of their centres and the inequality of the minutes might be corrected. Thus an accurate method of constructing an observatory was established and the difference which had existed between the computed and observed places of the fixed stars and planets by means of observing their mean motions and observations was removed.
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¹ Cf. Alberuni *Chronology of Ancient Nations* (p. 11), who writes: "It is impossible to fix the parts of the greatest circle by means of the parts of the smallest circle. I refer to the smallness of the instruments of observation in comparison with the vastness of the bodies which are to be observed. On this subject I have enlarged in my book called *Kitāb-al-istishhād bikhtilāj-al 'arṣād.*" L.P.E.A. Sédillot [p. cxxix] gives the following interesting quotations: "Si j'avais pu, disait Eln-Carfa, faire un cercle qui s'appuyat d'un coté sur les Pyramides et de l'autre sur le mont Mocattam, je l'aurais fait; car plus l'instrument est grand, plus les operations sont justes."
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² i.e., Delhi.
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³ See below p. 36 seq.
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⁴ To make the measurements fit, the cubit used must have been a large cubit=36 aṅgulas.
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Fig 5. OBVERSE OF ASTROLABE (JAIPUR A).
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Fig. 6. OBVERSE OF ASTROLABE (JAIPUR B).
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Fig 7. REVERSE OF ASTROLABE (JAIPUR A).
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Fig 8. REVERSE OF ASTROLABE (JAIPUR B).
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And, in order to confirm the truth of these observations, he constructed instruments of the same kind in Sawāī Jaipur, Muttra and Benares and Ujjain.⁵ When he compared these observatories, after allowing for the difference of longitude between the places where they stood, the observations agreed.⁶
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⁵ This implies that the Delhi Observatory was completed before the others were started; and that all of them were built before the preface was written. This dates the preface after 1734 and perhaps after 1737. (See p. 15).
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⁶ We must accept these statements about perfect agreement with some caution. We have very few records of Jai Singh's actual calculations or observations: his value for precession was 51.6" a year and for the obliquity 23° 28' 0.
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Hence he determined to erect similar observatories in other large cities so that every person who is devoted to these studies, whenever he wished to ascertain the place of a star or the relative situation of one star to another, might by these instruments observe the phenomena.⁷
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⁷ The project of building observatories at other places was never carried out.
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But seeing that in many cases it is necessary to determine past or future phenomena; and also that in the instant of their occurrence cloud or rain may prevent the observation—or the power and opportunity of access to an observatory may be wanting—he deemed it necessary that a table be constructed by means of which the daily places of the stars being calculated every year and disposed in a calendar may always be in readiness.
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In the same manner as the geometers and astronomers of antiquity bestowed many years on the practices of observation—thus, for the establishment of a certain method, after having constructed these instruments, the places of the stars were daily observed.
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After seven years had been spent in this employment¹ information was received that about this time observatories had been constructed in Europe² and that the learned of that country were employed in the prosecution of this important work: that the business of the observatory was still carrying on there and that they were constantly labouring to determine with accuracy the subtleties of this science.
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¹ The chronology is very uncertain. Delhi Observatory was constructed probably about 1724 and the tables, it is said, were finished in 1728; but there is evidence that leads us to the conclusion that this preface was written later. (See p. 139.)
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² Uraniborg (Tycho Brahe's observatory) in 1576; Leiden 1632; Paris 1667; Greenwich 1675; Berlin 1705; St. Petersburg 1725; Upsala 1730, etc.
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For this reason, having sent to that country several skilful persons along with PADRE MANUEL,³ and having procured the new tables which had been constructed there thirty years before and published under the name LIR,⁴ as well as the Europe tables anterior to those.⁵
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³ In 1728 or 1729 the Reverend Father Figueredo, a Portuguese Jesuit, went to Europe by the order of Jai Singh. Possibly this is the same man. See *Lettres édifiantes et curieuses*, xv, 269.
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⁴ La Hire's *Tabulae Astronomicae* was published in 1702; see p. 4. Father Boudier, who went to Delhi and Jaipur in 1734, actually refers to this edition. He writes: "En se servant de la méthode de M. de la Hire, édition de ses tables 1702, page 53, on a trouvé que le commencement de l'éclipse à Delhi, lorsqu'il était à Rome 11 heures 40 minutes 55 secondes du matin, etc.," *Lettres*, etc., xv, 288.
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⁵ We know that, besides La Hire's tables, Jai Singh possessed those of Ulugh Beg and Flamsteed. The latter's work contains also the tables of Tycho Brahe, the Landgrave Hesse, and Hevelius. Other possible tables are the Toletan Table of 1080; the Alfonsine Tables, 1252; Reinhold's Prussian Tables, 1551; Kepler's *Rudolphine Tables*, 1627; Cassini's tables, 1668 and 1693; Halley's tables, 1719; etc.
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On examining and comparing the calculations of these tables with actual observations it appeared that there was an error in the former in assigning the moon's place of half a degree. Although the error in the other planets was not so great, yet the times of solar and lunar eclipses he found to come out later or earlier than the truth by the fourth part of a ghaṭi or fifteen palas.⁶
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⁶ 60 palas=1 ghaṭi=24 minutes, and 15 palas=6 minutes.
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Hence he concluded that, since in Europe astronomical instruments have not been constructed of such a size and so large diameters, the motions which have been observed with them may have deviated a little from the truth.⁷
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⁷ The instruments used by Flamsteed (1646-1719) were an iron sextant of 6 feet radius; a three-foot quadrant; a mural arc of 140 degrees and radius 7 feet, 'divided with hitherto unapproached accuracy,' and with which all his most valuable work was executed; two clocks and two telescopes. For further particulars of European instruments, see p. 83.
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Since in this place by the aid of the unerring Artificer astronomical instruments have been constructed with all the exactness that the heart can desire and the motions of the stars have for a long period been constantly observed with them, agreeable to observations mean motions and equations were established; he found the calculation to agree perfectly with the observation. And although to this day the business of the observatory is carried on, a table under the name of His Majesty, the shadow of God, comprehending the most accurate rules, and most perfect methods of computation was constructed—so that, when the places of the stars and the appearance of the new moons and the eclipses of the sun and moon and the conjunction of the heavenly bodies are computed by it, they may arrive as near as possible at the truth, which, in fact, is every day seen and confirmed at the observatory.
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It therefore behoveth those who excel in this art, in return for so great a benefit, to offer up their prayers for the long continuance of the power and the prosperity of so good a King,¹ the safeguard of the earth, and thus obtain for themselves a blessing in both worlds.²
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¹ Muhammad Shāh died in A.D. 1748 five years after the death of Jai Singh.
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² There are some points about the preface that are not quite consistent with each other and known facts. The tradition is that the Zij Muḥammad Shāhī was completed in A.D. 1728 and this is, to some extent, confirmed by the Jaipur MS.; the preface was written some time after all the observatories had been built, that is after 1734, and "more than 300 years" after (the death of) Ulugh Beg [Ulugh Beg died in A.H. 853, and 853+300=1153 A.H.=A.D. 1740-1]. The legitimate conclusion is that the preface was written some considerable time after the tables had been completed.
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In 1902 Garrett wrote of the Zij Muḥammad Shāhī: "I have been unable to procure the Sanskrit original or even a vernacular copy" and "up to the present time the only copy of Jai Singh's astronomical tables, or Zeech Mahommed Shahi, which has been obtained is a book in Persian characters........ Unfortunately most of the figures are written in a kind of cypher, and although the key to this has been found, the thorough examination of this work will necessarily prove a long and laborious task" (pp. 18n. and 74). The British Museum Persian MS. is in excellent condition and although the tables are, of course, in the abjad notation, there would be no difficulty in translating them.
Linked texts (1)
- Sūryasiddhānta — Maya, Sanskrit