The Astronomical Observatories of Jai Singh c12.s1: Ujjain, the Greenwich of India

The Astronomical Observatories of Jai Singh c12.s1

Language: English

Ujjain, the Greenwich of India

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54. Ujjain (the οζηνη of the Greeks), or Avanti, as it was often called, is mentioned in early Hindu Astronomical works as situated on the prime meridian, and tradition also makes it the centre of astronomical learning in India.

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UJJAIN OBSERVATORY

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ELEVATION ON . A . B

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SECTION ON . E . F

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SECTION ON C . D.

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GENERAL PLAN.

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Latitude 23° 10' N Longitude 75° 47' E

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0 5 10 20 30 40 FEET

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In the *Pañchasiddhāntikā* (xiii, 17) we read: “Ujjayinī is near to Laṅkā, being situated to the north on the same meridian: hence the noon of the two places occurs at the same time, but their days are unequal with the exception of the equinoctial days.” The latitude is given (v. 19) as 24° N. and “the nāḍikās, arising from the difference in longitude from Yavana, are seven and a third in Avantī, nine in Vārāṇasī.” (iii, 13.)

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The *Sūrya Siddhānta* (i, 62) says: “Situated upon the line which passes through the haunt of the demons,² and the mountain which is the seat of the Gods,³ are Rohītaka and Avantī, as also the adjacent lake.”

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² Laṅkā.

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³ Mount Meru.

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Albīrūnī’s discussion of the position of Ujjain is of considerable interest. He writes⁴: “All canons of the Hindus agree in this that the line connecting Laṅkā with Meru divides the οἰκουμένη lengthwise in two halves, and that it passes through the city of Ujain, the fortress of Rohītaka, the river Yamunā,⁵ the plain of Tāneshar, and the Cold mountains. The longitudes of the places are measured by their distance from this line. On this head I know of no difference, except the following passage in the book of Āryabhaṭa of Kusumapura:—‘People say that Kurukshetra, *i.e.*, the plain of Tāneshar, lies on the line which connects Laṅkā with Meru, and passes through Ujjain. So they report on the authority of Pulīśa.⁶ But he was much too intelligent not to have known the subject better. The times of eclipses prove that statement to be erroneous, and Pṛithusvāmin maintains that the difference between the longitudes of Kurukshetra and Ujjain is 120 yojanas.’ These are the words of Āryabhaṭa. Ya‘ḳūb Ibn Ṭārik⁷ says in his book, entitled the Composition of the Spheres, that the latitude of Ujjain is 4⅓ degrees, but he does not say whether it lies in the north or south. Besides he states it, on the authority of the book *Al-Arkand*, to be 4⅓ degrees.⁸ We, however, found a totally different latitude of Ujain in the same book in a calculation relating to the distance between Ujain and Almanṣūra,⁹ which the author calls Brahmanavāṭa, *i.e.*, Bamhanwā, viz., latitude of Ujain, 22° 49′; latitude of Almanṣūra, 24° 1′. According to the same book, the straight shadow in Lohāniyye,¹⁰ *i.e.*, Loharāni, is 5⅝ digits. On the other hand, however, all the canons of the Hindus agree in this, that the latitude of Ujain is 24 degrees, and that the sun culminates over it at the time of the summer solstice.”

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¹ Yavana is Alexandria, whose longitude is approximately 29° 51′ E. of Greenwich. Seven and one-third nāḍikās=2 hours 56 minutes=44 degrees, and 9 nāḍikās=54°. These give the longitude of Ujjain and Vārāṇasī (Benares) as 73° 51′ and 83° 51′. Their longitudes are approximately 75° 47′ and 83° 0′ 46″.

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⁴ Alberuni’s India (By E. Sachau) i, 316.

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⁵ At Mathurā according to Albīrūnī (i. 308). Rohītaka, he says, is in the district of Multan. It was deserted in Albīrūnī’s time.

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⁶ Fl. circa A.D. 400.

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⁷ Died A.D. 796, see Suter, p. 4.

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⁸ This must be an equinoctial shadow length, which gives a latitude of tan⁻¹ 4 4/12 (or 4⅓) = 20° 57¼′ roughly. The correct latitude is about 23° 10′, which gives a shadow of 5⅝ digits.

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⁹ This is given on the ‘Jaipur B’ astrolabe, with latitude 27° 40′ North. See p. 127.

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¹⁰ Perhaps the Awyībaṣt of Ptolemy. tan⁻¹ 5⅝/12 = 25° 15′ nearly.

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Again he says (i, 308):—"The city of Ujain, which in the tables of the longitudes of places is mentioned as Uzain, and as situated on the sea, is in reality 100 yojana distant from the sea, etc."

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Bhāskara in his *Siddhānta Śiromaṇi* (Gaṇita, vii, 2) writes:—"The line which, passing above Laṅkā and Ujjayinī and touching the region of Kurukshetra and other places, goes through Meru—that line is by the wise regarded as the central meridian of the earth."

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Bhāskara also mentions Ujjain, in several other connexions, as the place of zero longitude, and he gives its latitude as 'one sixteenth of the whole circumference, north of the equator.' This is equivalent to 22½ degrees north, whereas the latitude of the present city is about 23° 11', that of Jai Singh's observatory being approximately 23° 10' 24". Another value was obtained from the length of the equinoctial shadow, which was given as 5 *daṇḍas* 10 minutes, or 310 minutes. This¹ is the shadow of a gnomon 12 *daṇḍas* or 720 minutes high, and hence the latitude= *tan*⁻¹ 310/720 = 23° 17' 40".

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¹ Guerin, *Astronomie Indien ne*, Paris, 1847, p. 146.

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55. The question of the formation of a new observatory at Ujjain is one of great importance. Ujjain is one of the most ancient astronomical centres in the world, and not only should it have a modern observatory, but it should be the centre of Hindu astronomical teaching. Perhaps, one of the most important practical questions to settle is the position of such an observatory, which is to be the position of zero longitude for Hindu astronomers, and is to accord with the traditional position of zero longitude. To assist in this very important matter the annexed map of Ujjain has, with the assistance of the Resident of Gwalior, the Director-General of Archæology and the Surveyor-General, been produced. The Trigonometrical Survey point on the map is Hill 1678, whose longitude is approximately 75°46'44", and latitude approximately 23° 11' 6" North. It is doubtful whether there ever was a fixed position in ancient Ujjain, which was considered as of zero longitude. Rather vaguely, the old city of Ujjain—to the north of the present city—was meant; or, it is just possible, that Jai Singh considered this point when he located his observatory to the south of the present city, and that the site of Jai Singh's observatory is the traditional place—but this is doubtful. The plan now to follow is to fix upon the position of the new observatory and determine its longitude and latitude independently of tradition. The accompanying map should be of help in obtaining the first approximations for the longitude and latitude of such a position, and it is hoped that it will be of use to the Paṇḍits of Ujjain.

Linked texts (5)

Sūryasiddhānta — Maya, Sanskrit
Āryabhaṭīya — Āryabhaṭa, Sanskrit
Pauliśasiddhānta — Sanskrit
Pañcasiddhāntikā — Varāhamihira, Sanskrit
Siddhāntaśiromaṇi — Bhāskara II, Sanskrit