The primary purpose of the observatory was to compile astronomical tables, and to predict the times and movements of the sun, moon and planets. Some of these purposes nowadays would be classified as astronomy.
Purpose of Individual StructuresThere are distinct instruments within the observatory of Jantar Mantar in New Delhi : the Samrat Yantra, the Ram Yantra, the Jayaprakash, and the Mishra yantras.
- Samrat Yantra: The Samrat Yantra, or Supreme Instrument, is a giant triangle that is basically an equal hour sundial. It is 70 feet high, 114 feet long at the base, and 10 feet thick. It has a 128-foot-long (39 m) hypotenuse that is parallel to the Earth's axis and points toward the North Pole. On either side of the triangle is a quadrant with graduations indicating hours, minutes, and seconds. At the time of the Samrat Yantra's construction, sundials already existed, but the Samrat Yantra turned the basic sundial into a precision tool for measuring declination and other related coordinates of various heavenly bodies.
- Jayaprakash Yantra: The Jayaprakash consists of hollowed out hemispheres with markings on their concave surfaces. Crosswires were stretched between points on their rim. From inside the Ram, an observer could align the position of a star with various markings or a window's edge.
- Mishra Yantra: The Mishra yantras were able to indicate when it was noon in various cities all over the world and was the only structure in the observatory not invented by Jai Singh II.
In all, between 1727 and 1734, Jai Singh II, built five similar observatories, Yantra Mantras, in west central India, all known by the same name, thus includes ones at Jaipur - Yantra Mantra (Jaipur), Ujjain, Mathura and Varanasi.Today the observatory is mainly a tourist attraction, and is significant in the history of astronomy.
The above text courtesy from wikipedia.org website.
In my collection i have a vintage post card of this Jantar Mantar Delhi.
This is my Jantar Mantar Delhi vintage post card.