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The Jantar-Mantar of Delhi. The Indian astronomer Maharaja Sawai Jai Singh II (1688-1743 AD) built a series of stone observatories throughout India. Pictured here is an overview of the observatory in Delhi. The structure to the right is the gnomon of a great sundial (those are normal sized stairs leading up its edge).
The Jantar-Mantar of Jaipur. This is an overview of the observatory in Jaipur. At the top center is the small equatorial sundial (Laghu Samrat Yantra), which can measure time to a precision of about 20 seconds. To the right are the hemispherical sundials (Narivalaya), with the southern sundial facing the camera. In the foreground is the armillary sphere instrument (Jai Prakash Yantra). A small ring is suspended on wires over each marble bowl. During the day, the shadow cast by the ring can be used for determining the solar position. At night, one peered up through the ring from beneath the marble slabs of the bowls to determine star positions. The two bowls are complementary- where one has slabs, the other has slots. The bowls were used alternately from one hour to the next.
The Zodiacal Instruments (Rashi Yantras). These instruments in Jaipur were used to observe the latitudes and longitudes of the sun and planets. Although they appear to be sundials, they are in fact quite different. The angle and orientation of the gnomons are related to the positions of individual Zodiacal signs at the time of observation (any one instrument can only be used for about 2 hours of any day).
