The Astronomical Observatories of Jai Singh c9.s1.32

c9.s1.32

33(a). The Shasthāmśa Yantra (‘Sextant’) occurs at Delhi and Jaipur only and is really another form of meridian circle. It is a large graduated arc lying in the meridian and is built in a ‘dark room’ at the bottom of the masonry work that supports the huge quadrants of the Samrāṭ Yantra. A small orifice some 30 or 40 feet above admits the light of the sun at noon and the image of the sun on the graduated arc marks with fair accuracy the sun’s altitude. It is thus the aperture dial of the Muslims (see p. 82). At Jaipur there are two ‘dark rooms,’ one under each quadrant of the Samrāṭ and in each room are two arcs the radius of each being 28 feet 4 inches. The ‘dark room’ at Delhi is at present inaccessible.