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Welcome to this audio-visual and observational tour of the Jantar Mantar Observatory Jaipur, which is located at a Latitude of 26 degrees and 55 minutes North, and a Longitude of 75 degrees and 49 minutes East.

This observatory was built by Maharaja Sawai Jai Singh, when he found that the observed positions of celestial objects did not coincide with theoretical predictions based on classical astronomical calculations. He intended that accurate observations with his instruments should be the starting point for preparing astronomical tables and obtaining correct theoretical calculations of future events.

Raja Jai Singh built the observatory with yet another purpose - that astronomical observations related to positions of celestial objects, should be something very easily possible, for the aam aadmi to do. Be with us during this tour of the observatory and you will see that, indeed, it is very simple to make actual observations with the instruments in this observatory, measure time, and also measure positions of celestial objects. What is more, you will also see that such measurements are not dry and technical, but, rather fun to do :-)

We see here masonry instruments built during the period 1728-1734. What will amaze you is the possible accuracy of celestial measurements that such historical instruments can achieve and more importantly, the user friendly nature of these instruments, compared to modern day astronomical equipment.

Jai Singh first used many instruments in brass. He however, felt that the brass instruments had many associated problems of stability as well as limitation in accuracy due to their relatively smaller feasible size. Jai Singh, therefore, built large masonry instruments as he felt that better accuracies were obtainable with the large size of these instruments. He initially made wax models of his instruments, with his own hands. He then went on to have them built on gigantic scale, in masonry, confident of the accuracies that he could achieve with these instruments. His intentions were perhaps poignantly anachronistic, as better accuracies were already being obtained with telescopes in Europe, for some decades already, by that time.

Masonry instruments had their uses for cutting edge development of astronomy, in the 16th century. The Uraniborg observatory of Tycho Brahe on the island of Hven, was built around 1576 AD and was the last major research observatory to have been built without a telescope. The usage of telescope for celestial observations started early in the 17th century and grew towards accurate position measurements for celestial objects with additional instrumentation like the vernier and micrometer screwguage added to the telescope. Once such instrumentation for a telescope was done, a small telescope could do so much better than a gigantic masonry instrument, for measuring the exact positions of celestial objects in the sky. Of course, some masonry or brass instruments like quandrants and transit circles continued to be used in observatories world wide, in Jai Singh’s times. Telescopes, however, were by then, the main instruments of an observatory, anywhere else in the world.

Jai Singh had studied different schools of astronomy from material that was available to him. He interacted with Jesuit astronomers than traveling in India and also sent a scientific expedition to Spain and Portugal. He received information about the progress in European astronomy from this expedition, but, perhaps from a conservative point of view, as he did not seem to have been much aware of the scientific revolutions that had taken place in Europe, in the 17th century. Astronomical tables and a telescope were also received by him through this expedition. Perhaps the telescope itself was not of a superior quality and did not have the instrumentation necessary to make accurate positional astronomy measurements, as Jai Singh discarded its revolutionary possibilities and went ahead with the construction of his massive masonry instruments.

Poignantly anachronistic, his instruments might have been. However, Jai Singh’s instruments did give him reasonably accurate observations for him to have refine the panchang, and his observations, calculations and predicted tables formed the basis of the traditional panchang in Rajasthan to this date. His instruments have also survived these 300 years and could continue to serve as very useful teaching laboratories of positional astronomy for students.

As a builder of public utility instruments with teaching capabilities then, Jai Singh was perhaps far ahead of his times :-)

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Page last modified on June 14, 2008, at 07:18 AM EST