The Astronomical Observatories of Jai Singh c11.s2.t1: In the Museum
The Astronomical Observatories of Jai Singh c11.s2.t1
- Language
- English
In the Museum
c11.s2.t1.1
| Astrolabe A | . . . . . . . | Figures 5 and 7. |
| ” B | . . . . . . . | ” 6, 8, and 13. |
| ” D | . . . . . . . | ” 10, 11 and 14. |
| Zarqāli astrolabe | . . . . . . . | ” 19 and 20. |
| Miscellaneous | . . . . . . . | ” 26, 27. |
c11.s2.t1.2
47. Samrāṭ Yantra.—The large Samrāṭ Yantra is situated at the south-east corner of the observatory enclosure. It is the largest of all of Jai Singh's instruments, being nearly 90 feet high and 147 feet long, the radius of each quadrant being 49 feet 10 inches. It is graduated to read to seconds, but this is impossible in practice, owing to the ill-defined shadow (i.e., due to the size of penumbra). The tangent scales on the edge of the gnomon (see p. 36) cannot now be used, owing to the instrument overlooking the palace zenana enclosure. The readings of the quadrants appear to be slightly inconsistent, the eastern quadrant giving readings that are about two minutes out, as compared with the time registered on the western quadrant.
c11.s2.t1.3
The general structure is the same as that of the Delhi instrument, but it is of somewhat more elaborate construction and on a larger scale. Like the Delhi instrument, the foundations are below the ground level, but the floor is pukka, and proper arrangements are made for drainage.
c11.s2.t1.4
Shasṭhāṃsa Yantra.—The Shasṭhāṃsa Yantra, or sextant instrument, is a huge convex arc of 60 degrees, and of 28 feet 4 inches radius, lying in the meridian. There are two pairs of such arcs built into the masonry that supports the east and west ends of the Samrāṭ quadrants. Small holes in the roof of each structure allows the sunlight to fall on the arc at noon. The instrument is capable of giving very accurate results, but the readings are said to be in error to about 4 minutes.
c11.s2.t1.5
Rāśi Valaya Yantra.—The Rāśi Valaya, or ‘ecliptic instrument,’ consists of a collection of dials, situated on a platform to the west of the Samrāṭ Yantra (Plate XXI and figures 54 and 55). There are twelve such dials, one for each sign of the zodiac (that for Capricornus is seen in figure 55), and each instrument is exactly of the same type as the Samrāṭ Yantra, but the quadrants lie, not in the plane of the equator, but in the plane of the ecliptic when the particular sign is on the horizon, and the edge of the gnomon then points to the pole of the ecliptic; consequently, at the proper moment the instrument indicates the sun's latitude and (with appropriate graduations) longitude. The radius of the quadrant is 5 feet 6 inches in the case of four instruments, and 4 feet 1¼ inches in the case of the other eight. The contemporary lists do not mention the Rāśi Valaya.
c11.s2.t1.6
Jai Prakāś.—The Jai Prakāś is constructed in the same manner as the Delhi instrument (Plate XXI and figure 30). The principle of the instrument has already been explained (p. 37). It was completely restored in 1901, in white marble, and the various circles were then marked in different colours.¹ It is 17 feet 10 inches in diameter. The instrument shows time and declination, and the signs on the meridian.
c11.s2.t1.7
¹ The colours have since disappeared.
c11.s2.t1.8
Kapāla.—The Kapāla is another hemispherical instrument, and is peculiar to Jaipur (figure 31). There are two examples—one being a hemisphere with its upper edge representing, as in the Jai Prakāś, the plane of the horizon, while in the other it represents the solstitial colure. The latter indicates ‘rising signs’ instead of meridian signs. Each Kapāla has a diameter of 11⅓ feet and is a complete hemisphere, that is, no pathways are cut, as in the Jai Prākāś. The graduated rims are in marble, but the remainder of the surfaces are in lime plaster.
c11.s2.t1.9
JAIPUR OBSERVATORY
c11.s2.t1.10
SCALE
c11.s2.t1.11
Latitude 26° 55' 27" Longitude 75° 49' 18"
c11.s2.t1.12
DAKSHINOTARA VITTI YANTRA
c11.s2.t1.13
UNNATAMSA YANTRA
c11.s2.t1.14
VANTRA RAJ
c11.s2.t1.15
NARI VALAYA YANTRA
c11.s2.t1.16
SAMRAT YANTRA
c11.s2.t1.17
JAI PRAKASH
c11.s2.t1.18
KAPALA
c11.s2.t1.19
DIGAMSA YANTRA
c11.s2.t1.20
RAM YANTRA
c11.s2.t1.21
SAMRAT YANTRA
c11.s2.t1.22
NARI VALAYA
c11.s2.t1.23
GENERAL PLAN.
c11.s2.t1.24
Rām Yantra.—There are four instruments in white marble (plate XXI and figure 59), but all of them are quite modern (? 1891), and were made according to Jagannāth's instructions. In principle they are exactly the same as the instruments at Delhi, but are much smaller, the larger pair being 23 feet 11 inches in diameter. The sectors are twelve in number, occupying 12° each in one instrument, and 18° in the other. For an explanation of the construction see p. 37.
c11.s2.t1.25
Digamśa Yantra.—The Digamśa Yantra or azimuth instrument has already been described (p. 38). There is no such instrument at Delhi, but there are examples at Ujjain and Benares (Plate XXI).
c11.s2.t1.26
Nari Valaya Yantra.—There are similar instruments, but much smaller, at Ujjain and Benares. The instrument at Jaipur is a masonry cylinder some 10 feet in diameter.¹ The axis of the cylinder is horizontal and in the plane of the meridian, and the parallel faces, which form the dials, are in the plane of the equator. The dials are graduated into ghaṭis and palas, and also hours and minutes. According to Garrett, the southern face was added by Jai Singh's grandson, Mahārāja Purṭāp Singh.
c11.s2.t1.27
¹ In the general plan (plate XXI) the supporting masonry work is not shown, but see figure 53.
c11.s2.t1.28
Dakṣiṇovṛtti Yantra.—The construction of the Dakṣiṇo Vṛtti Yantra, or mural quadrant, is clearly seen in plates XXI and figure 56. It is of the same principle as the similar instruments at Ujjain and Benares (that at Delhi has disappeared). On the east face are two quadrants of 20 feet radius, and on the west face is a semicircle of 19 feet 10 inches radius. It was used for taking meridian altitudes.
c11.s2.t1.29
The metal instruments have already been described in detail (page 16 seq.).
c11.s2.t1.30
48. History.—Jaipur city was built about A.D. 1728, and the observatory was constructed about A.D. 1734. The earliest detailed description is that by Tieffenthaler, a Jesuit Missionary, who travelled in India from 1743, the date of Jai Singh's death, to 1786; but the earliest reference to the observatory is possibly that by Father Boudier, who, with another priest, visited Jaipur in 1834, and made observations. He makes no references to the instruments,² and they were possibly only in the course of construction at the time of his visit. He, however, made observations for the determination of the latitude and longitude of the observatory itself.³
c11.s2.t1.31
² Neither does he make any reference to the instruments at Delhi, although he made observations there long after the observatory was built.
c11.s2.t1.32
³ Lettres édifiantes, etc., pp. 269-290. See page 6.
c11.s2.t1.33
Tieffenthaler's description⁴ of the observatory is as follows:—
c11.s2.t1.34
⁴ Des Pater Joseph Tieffenthaler's historisch-geographische Beschreibung von Hindustan, 1785, vo'. I, p. 244/. French edition. p. 316/.
c11.s2.t1.35
"But a place that deserves detailed description is that where astronomical observations are made: it is such a work as is never seen in this part of the world, and, by the novelty and grandeur of the instruments, strikes one with
c11.s2.t1.36
astonishment. This large and spacious observatory is close to the King's palace. It is situated on a plain surrounded by walls and was constructed especially for the contemplation of the stars.
c11.s2.t1.37
“On entering, one first sees the twelve figures of the Zodiac, all arranged in a large circle, and made of purest lime. Next are seen diverse sections of the astronomical sphere, fixed according to the height of the pole at the place—with diameters of 12 or more Paris feet,¹ and besides these, some large and small equinoctial dials, and some astrolabes made in lime, also a meridian line and a horizontal dial engraved on a very large stone.
c11.s2.t1.38
¹ 12 Paris feet=12·8 English feet approximately.
c11.s2.t1.39
“But what attracts most attention is a gnomon (axis mundi), remarkable for its height of 70 Paris feet,² and for its thickness—constructed in brick and lime, situated in the plane of the meridian, with an angle equal to the height of the pole. On the summit of this gnomon is a belvedere, which overlooks all the town and is so high that it makes one giddy. The shadow of this gigantic gnomon falls on a prodigiously large astronomical semi-circle, of which the horns are turned towards the sky. It is artistically constructed in whitest lime or gypsum, and is graduated in degrees and minutes. In the morning the shadow falls on the western quadrant, and in the evening on that towards the east, and, as the gnomon lies between both the quadrants, the sun's altitude can be found at any moment. A double dial, constructed also in lime, is seen near these quadrants. It is enclosed in a kind of chamber, on either side of which it is raised. When the sun passes the meridian a ray of this star enters through each of two holes pierced in a sheet of copper, and when these rays fall exactly on the middle of the two quadrants, low in summer and higher in winter, the sun is in the meridian sign, and its meridian height is indicated.
c11.s2.t1.40
² 70 Paris feet=74½ English feet approximately.
c11.s2.t1.41
“The instruments which follow have similar graduations: there are three very large astrolabes cast in copper, suspended by iron rings; a circle also of cast copper, fitted with a rule (or alhidade), and elevated at the height of the pole, suitable for determining the declination of the sun—for, when you turn this instrument towards the sun, it will indicate the declination on the ground.
c11.s2.t1.42
“I pass over in silence other less important instruments, but a matter which detracts from the value of the observatory is that, in a low situation surrounded by walls, the observer cannot see the rising and setting of the stars; also the dial, gnomon and other parts being in lime plaster prevent one from making very exact observations.”
c11.s2.t1.43
49. Restorations.—The Jaipur observatory, being situated in the palace precincts, has been carefully preserved, and has been added to from time to time. Possibly the Rāśi Valaya was added after Jai Singh's reign, and possibly some of the brass instruments were brought from the Delhi observatory, but we have no direct information on these points. Some additions appear to have been made in 1891, and in 1901 His Highness the present Mahārāja decided to restore the observatory completely. The services of Lieutenant A. H. Garrett, R.E., were lent and the work was finished in 1902, in which year also Lieutenant Garrett, assisted by Pandit Chandradhar Guleri, prepared and published an account of the observatory. This account, as far as the descriptions of the instruments are concerned, is an excellent one, but the parts relating to the history of astronomy are not so reliable. It is difficult to judge of the work of restoration, as no reliable account of the observatory before the restoration took place is available. Colonel Hendley, in 1886, gave a rough plan of the observatory, and a list of the instruments,¹ but not in sufficient detail for purposes of comparison.
c11.s2.t1.44
¹ London Indo-Colonial Exhibition in 1886. Handbook of the Jeypore Courts. pp. 59-62
c11.s2.t1.45
Fig 57. CHAKRA YANTRA, (EQUATORIAL) JAIPUR.
c11.s2.t1.46
Fig 59. RAM YANTRA, JAIPUR.
c11.s2.t1.47
Fig 56. DAKSHINO VRITTI YANTRA, JAIPUR.
c11.s2.t1.48
Fig 58. KRANTI VALAYA, JAIPUR.
c11.s2.t1.49
Lieutenant Garrett's work has been somewhat severely criticised in one respect.² He found that the Rāśi Valaya instruments did not accord altogether with his idea of their use, and altered the angles slightly. He assumed that each instrument corresponded to a 'rising sign,' and was to be used at the time of rising of the particular sign for the measurement of celestial latitude and longitude. The following table shows the actual alterations made in the twelve instruments corresponding to the twelve signs:—
c11.s2.t1.50
² Indian Antiquary, XXXV, 1906, p. 34.
c11.s2.t1.51
| Signs. | MEASUREMENTS OF GNOMONS BEFORE ALTERATION. | MEASUREMENTS OF GNOMONS AFTER ALTERATION. |
| | Azimuth. | Altitude. | Azimuth. | Altitude. |
| | ° ′ | ° ′ | ° ′ | ° ′ |
| Aries . . . . . . . . . . | -26 0 | 27 0 | -25 56 | 24 32 |
| Taurus . . . . . . . . . . | -21 30 | 15 30 | -21 17 | 14 25 |
| Gemini . . . . . . . . . . | -12 30 | 7 0 | -12 19 | 6 36 |
| Cancer . . . . . . . . . . | 0 0 | 3 30 | 0 0 | 3 28 |
| Leo . . . . . . . . . . | 12 30 | 7 0 | 12 19 | 6 31 |
| Virgo . . . . . . . . . . | 21 30 | 15 30 | 21 17 | 14 25 |
| Libra . . . . . . . . . . | 26 0 | 27 0 | 25 56 | 24 32 |
| Scorpio . . . . . . . . . . | 26 0 | 38 0 | 25 37 | 35 33 |
| Sagittarius . . . . . . . . . . | 18 0 | 46 30 | 17 40 | 45 42 |
| Capricornus . . . . . . . . . . | 0 0 | 50 30 | 0 0 | 50 22 |
| Aquarius . . . . . . . . . . | -18 0 | 46 30 | -17 40 | 45 42 |
| Pisces . . . . . . . . . . | -26 6 | 38 0 | -25 37 | 35 33 |
| | Maximum alteration | 0 29 | 2 28 |