The Astronomical Observatories of Jai Singh c6.s1.t1.46

c6.s1.t1.46

(d) There are generally four sets of shadow scales³ two on the periphery of the lower half of the disc and two in the central rectangle. In the Zarqālī instrument, however, the latter are replaced by a pair of central circular shadow scales (figure 19). Given the length of the shadow in terms of its gnomon—by the aid of the shadow scale and the alhidade the degree of altitude of the sun and the time can be found.