is derived from the Sanskrit words
which mean instruments and formulae. This medieval wonder was built to verify astronomical observations made at Jaipur
, and for religious purposes. It is the largest and best preserved of five observatories built by Jai Singh who had a deep interest in astronomy. It includes 13 different instruments for calculating the time of day, the altitudes of heavenly bodies, and positions of constellations. jai Singh seems to have had very precise ideas of accuracy, to ensure which he made gigantic instruments from stone, masonry, and marble. These include Samrat Yantra, Laghu Samrat Yantra, and Rashi Yantras.