INTRODUCTION xi Verses 1-2 (i) give the method for finding the directions— east, west, north, and south. Verses 2(ii)-3 give a rule for finding the local latitude from the equinoctial midday shadow. Verses 4-6 relate to the times of rising of the signs at the equator and at the local place. Verses 7-11 and 12-15 give rules for finding the Sun's altitude and zenith distance with the help of the time elapsed since sunrise (in the forenoon) or to elapse before sunset (in the afternoon), and vice versa. Verse 16 relates to the determination of the sahkvagra (i.e., the distance of the Sun's projection on the plane of the celestial horizon, from the Sun's rising-setting line). Verses 17-19 give a method for finding the longitude of the rising point of the ecliptic with the help of the Sun's instan- taneous longitude and the time elapsed since sunrise. Verse 20 gives a rule for finding the time elapsed since sunrise with the help of the instantaneous longitudes of the Sun and the rising point of the ecliptic. Verse 21 relates to the determination of the Rsine (= Radius X sine) of the Sun's agrt [i.e., the distance between the east- west line and the Sun's rising-setting line). Verses 22-23 relate to the calculation of the Sun's prime vertical altitude and the derivation of the shadow of the gnomon therefrom. Verses 24-25 give a rule for finding the Sun's longitude with the help of the prime vertical shadow of the gnomon. Verse 26 gives a rule for finding the arc corresponding to a given Rsine. [The converse of this was already given in ii. 2(ii)-3(i).] Verses 27-28 give a rule for finding the Sun's altitude and zenith- distance, and the midday shadow of the gnomon with the help of the Sun's declination and the local latitude.
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