The Astronomical Observatories of Jai Singh c13.10

c13.10

On the east wall of the gnomon are two graduated quadrants (figure 66), used as a Dakṣiṇovṛitti Yantra or meridian instrument. Each quadrant has a radius of 10 feet 7 inches. The shadow of one of the pins (fixed at the top of each quadrant) gives the zenith distance at noon, and zenith distances of other heavenly bodies could be observed directly, by moving the eye along the appropriate quadrants. Under these quadrants is a platform (shown in the plan) for the observer. Apparently, in 1773, these quadrants were not in existence (see figure 67), but according to Paṇḍit Bapu Deva Śāstri they were there in 1865.