The Astronomical Observatories of Jai Singh c9.s1.2

c9.s1.2

These dials give apparent solar time, which varies from day to day, owing to (1) the eccentricity of the earth’s orbit and its consequent more rapid angular motion in the winter (when it is nearer the sun) and its slower motion in summer; (2) the obliquity of the ecliptic.³ Consequently a clock going regularly does not agree for long with solar time. In India there is another element of difference to consider, due to the standard time being fixed for the longitude of 82½° degree east of Greenwich, or 5½ hours before Greenwich time. A table that will enable the observer to compare roughly the dial time with clock time is given in appendix C.