Maharaja Sawai Jai Singh II (1686-1743) was the erstwhile ruler of Amber
. He was a great patron of architecture and astronomy. He was a feudatory ruler in the Mughal Empire
. He was given the title ‘sawai’, meaning one and quarter, by Emperor Aurangzeb
. This title meant that Jai Singh II was a quarter superior than his predecessor, Mirza Raja Jai Singh. He earned this title after capturing the Vishalgarh fort from the Marathas.
Maharaja Sawai Jai Singh II maintained his good relations with Mughal rulers, even during turbulent times. Under the patronage of the Mughal emperor, he built the Jantar Mantar observatory at New Delhi in 1724. Similar observatories were built at Jaipur in 1734 and then at Mathura, Ujjain and Varanasi between 1732 and 1734. These observatories were sophisticated enough to measure the exact planetary positions and time with the precision of one second. These observatories were built with the help of a scholar from West Bengal named Pandit Vidyadhar Bhattacharya. The scholarly person was also the architect of the new capital city of Jaipur. The architecture and plan of this city was so impressive and perfect that it earned the laurels of renowned European travelers such as Louis Rousselet and an English bishop named Heber.
Jai Singh had a good collection of astronomical manuscripts and tables from Arabia and Europe. He had them translated to Sanskrit. He even brought telescopes from Europe. Using these telescopes, he corrected the traditional astronomy tables. Some of the instruments of astronomy designed by him can be seen at the Jantar Mantar observatory in New Delhi.