The Astronomical Observatories of Jai Singh c9.s1.30

c9.s1.30

32. The Narivalaya Yantra (‘Circular dial’) is mentioned by Jagannāth and it occurs at Jaipur, Ujjain and Benares. It may be described as a cylindrical dial—the axis of the cylinder pointing north and south, and the northern and southern faces being parallel to the plane of the equator. At the centre of each face, and at right angles to it, is an iron style surrounded by circles graduated into hours and minutes and ghaṭis and palas respectively. The shadow of the style marks the time of the day, and the instrument also shows, very effectively, the passage of the sun across the equator (the equinoxes). See figures 53 and 65. Jagannāth remarks, about this instrument, that it is not of much value, because it only gives readings for northerly observations. This applies to some extent to the Benares instrument (see figure 65), but not to those at Ujjain and Jaipur.