Jai Prakash sundials. These hemispherical bowls are part of an astronomical observatory built in Jaipur between 1727 and 1734 by Maharaja Jai Singh II. The surface of each bowl is made from six marble slabs, which have been engraved with graduations corresponding to the positions of the stars in the southern hemisphere. A crosswire suspended across the rim of the bowl holds a metal ring that identifies the position of the Sun, allowing the calculation of time during the day. At night, observers look at celestial bodies through the ring.