Jai Praksh Yantra
Several devices however, first and foremost the hemispheres of Jai Praksh Yantra which are set in the ground, are attributed to Jai Singh as new constructions. Two walkable complementary marble hemispheres set in the ground about 4 metres in diameter - in itself a master piece - where above a cross with a metal ring is applied. The inside surface is covered with coordinate lines. During the day the shadow of the metal ring allows to read the exact position of the sun on the coordinate lines, and of course the time. During the night a simple tube was used as a sighting device for observation.
The complementary hemispheres of Jai Praksh Yantra.
Behind of it some of the 12 zodiac gnomes used for measuring celestial coordinates