Jantar Mantar, Jaipur

Duration of Openings (Hrs.): 9.00-16.30 Entry Fee (In Indian Rupees): Indian : 40 (15 Student) Foreigner : 200 (100 Student) Tel: +91 141 2610494

The Instruments of the Jantar Mantar,Jaipur

Like its Delhi counterpart, the observatory at Jaipur consists of nine different instruments of which smaller implements, such as the sextant and the astrolabe, are contained within. The Jantar Mantar is unique in this aspect as these are still in an excellent state of repair, unlike in Delhi:
The Samrat Yantra The Dakshino Bhitti Yantra The Digamsa Yantra The Rashi Valaya Yantra The Jai Prakash Yantra (Great and Small) The Shastansha Yantra The Unnatasha Yantra The Narivalaya Uttar Gola Yantra The Rama Yantra The functions, operation and coordinate measurements of these nine instruments vary. Some of them actually complement one another -- for example, the Digamsa Yantra was built to complement the Samrat Yantra because of the latter’s limitations in taking azimuthal and altitudinal readings of the stars in certain positions.

The Samrat Yantra in Jantar Mantar, Jaipur

The Samrat Yantra (Supreme Instrument) dominates the landscape of the observatory and is very much the crowning glory of the Jaipur observatory. Widely accepted to have been constructed by Jai Singh himself in 1724, its aspect and rationale is not unfamiliar in any astronomical context: in essence it is a large sundial. Hence its principal purpose was to conduct solar time-reading duties. Additionally, as an extrapolation of its function, it was able to trace the path of stars, reveal the duration of day-night, and verify the location of the Pole Star. Versions of the Samrat Yantra may be found at all the observatories built by Jai Singh; indeed also in other archeo-astronomical sites around the world.13 It is certainly not a departure from the primary time-telling concept of the simple sundial and bears testament to the evergreen fundamentals which form the backbone of modern-day astronomy.
The Jantar Mantar at Jaipur thus evidently served a different purpose from that of Delhi. The latter was essentially built for the sole purpose of improving the Indian astrological tables and calendar. These had already been completed by the time the Jaipur observatory was constructed, thus obviating the need for further astronomical data collection. Instead, the Jantar Mantar at Jaipur was built mainly for religious purposes. With the benefit of hindsight, his judgement in abstaining from the use of sighting equipment apposite to instruments of that age is perhaps more related to Hindu philosophy: depiction of the cosmos and godly realms endow upon the expert the mandate of knowledge and power over this world far exceeding the information they truly provide. In doing so, Jai Singh would then have become the apotheosis of all things divine.

The Small Jai Prakash Yantra in Jantar Mantar, Jaipur

The Small Jai Prakash Yantra is a complete hemisphere made of sections of white marble sunk into a horizontal platform with its top open. This sunken hemisphere, as described, inversely represents the celestial sphere above it. As such, the North Celestial pole is laterally inverted in with respect to the surface of the hemisphere in comparison with the celestial sphere. This enables easy reading for the observer. The diagram should clearly illustrate this concept. This is, in essence, similar to the concept of seeing the sun moving clockwise in the northern hemisphere and counter clockwise in the southern hemisphere, i.e. things appear laterally inverted if views are taken from vertically opposite sides of the earth.

Jai Prakash Yantras in Jantar Mantar, Jaipur

The Great Jai Prakash Yantra It was the limitation of the Small Jai Prakash Yantras that caused Jai Singh to build the Great Not only was the hemisphere enlarged substantially, the surface was divided into sections. Each alternate slab was reassembled into a second hemisphere. In the second hemisphere the pieces were assembled in such a way that the gaps between the pieces would fit exactly into the position of the pieces in the first hemisphere, such that the two hemispheres when fitted together make a whole. The drawing below should illustrate this clearly.

The Rama Yantra in Jantar Mantar, Jaipur

The Rama Yantra was used to measure both the position of the sun and stars. Unlike the Jai Prakash Yantra, which used a ring as its gnomon, the Rama Yantra used a stick in the center of a flat elevated circular scaled surface as its gnomon. Also, it used only one coordinate measurement system, instead of two. It was based on the horizon and zenith system.

The Digamsa Yantra in Jantar Mantar, Jaipur

The design and function system of the Digamsa Yantra was relatively less complex than the Jai Prakash and Rama Yantras. The only purpose it was built was to provide accurate azimuthal readings to complement the Rama Yantra.

The Rashi Valaya Yantras in Jantar Mantar, Jaipur

As mentioned above, the manner in which the Rashi Valaya Yantras were constructed was similar to the Samrat Yantra. However, the slope of the gnomon of each of the twelve Rashi Valaya Yantras varied with respect to the horizon and pointed in different directions. The twelve Rashi Valaya Yantras were intended to be built symmetrically on a platform that represents the horizon. However, the symmetry was somewhat broken to an extent by the positions of the Aquarius and Gemini Yantras which were shifted a southward with respect to the Sagittarius and Leo Yantras at the other and of the symmetrical formation. Save in the pictures below.