The Astrological Observatory of Sawai Jai Singh II. The purpose of these observatories was to precisely fix the astrological dates that governed the life of the Hindu people, who consulted the stars before undertaking any great event. The basic premises behind Jantar Mantar are simple but ingenious. First, one way to reduce the inaccuracy of the instruments was to make them as large as humanly possible, while another way was to make instruments without moving parts, cutting down on a second source of errors. Finally, the observatory consists of a whole series of instruments which are interrelated, so that each may help calibrate and measure the accuracy of the others. In this manner, the measurements of the heavens do not remain dependent upon one primary instrument, from which all the rest take their bearings.

Click on Thumbnails for explanations of each instrument. To see as a slideshow, click on the link at the top right.