50 (resulting) quotient should be subtracted or added the earthsine according as the Sun is in the northern or southern hemisphere. Then having multiplied that (result) by the radius and divided by the day-radius, to the arc of the (resulting) quotient add or subtract from the same arc the 05us of the (Sun's) ascensional difference (according as the Sun is) in the northern or southern hemisphere. (Dividing the resulting 25us) by 6 and again by 60 should be determined the ghas elapsed (since sumrise) and to elapse (before sunset) in the first half and the second half of the day (respectively). This rule is the converse of that given in starm2as 7-10 above. A rule for the calculation of the Sun's saikuagra : 16. The Rsine of the Sun's altitude multiplied by the Rsine of the latitude and divided by the Rsine of the colatitude is the (Sun's) 5aikuagra, which is always to the south of the rising-setting line. The Sun's 5aikuagra denotes the distance of the Sun's projection from the (sum's) rising-setting line . In Fig. 6,S denotes the Sun, A the foot of the perpendicular dropped from the Sun on the plane of the celestial horizon, SB the perpendicular from S on the rising-setting line, and AB the perpendicmlar from A on the rising setting line. So AB is evidently the 5aiku4grou. Since SA = Rsin ८, AB = saikण्0gra, //SBA = 90-4, //८ASB = }, therefore, we have giving AB 1 Cf. MBh, i.27-28(). SA Rcos Fig. 6
