Jantar Mantar

A Jantar Mantar (जंतर मंतर, Hindustani pronunciation: [d͡ʒən̪t̪ər mən̪t̪ər] ‘calculation instruments’) is an assembly of stone-built astronomical instruments, designed to be used with the naked eye. There were five Jantar Mantars in India, built between 1724 and 1735. All were built at the command of the Sawai Jai Singh, who had a keen interest in mathematics, architecture and astronomy. A total of five Jantar Mantars were constructed across North India: Jaipur, Delhi, Ujjain, Varanasi, and Mathura (the last of which no longer exists). These compilations or Mishra Yantra (‘mixed instruments’) gather up to 19 different astronomical instruments. The largest example is the equinoctial sundial belonging to Jaipur's assembly of instruments, consisting of a gigantic triangular gnomon with the hypotenuse parallel to the Earth's axis. On either side of the gnomon is a quadrant of a circle, parallel to the plane of the equator. The instrument can be used with an accuracy of about 20 seconds by a skilled observer to determine the time of day, and the declination of the Sun and the other heavenly bodies. It is the world's largest stone sundial, and is known as the Samrat Yantra.The Jaipur Jantar Mantar is a UNESCO World Heritage Site. == History == In the early 18th century, Sawai Jai Singh of Jaipur constructed five Jantar Mantar in total, in New Delhi, Jaipur, Ujjain, Mathura and Varanasi; they were completed between 1724 and 1735.