26 MEAN LONGITUDE OF A PLANET A rule for finding the mean longitude of the sighrocca of Venus, and also giving the additives for the sighrocca of Mercury and the Moon : 35. Multiply the grahatanu by 37 and divide by 900: these are the degrees, etc., (forming part) of the (mean) longitude of (the sighrocca of) Venus. Then divide the grahatanu by 100: these are seconds. Add to these one-third of the Sun's (mean) longitude (in revolutions, etc.). Then subtract the whole of that (sum) from two times the Sun's (mean) longitude. (The difference thus obtained is the mean longitude of the sighrocca of Venus). ¹ To the (mean) longitudes of (the sighrocca of) Mercury and the Moon add four times the Sun's (mean) longitude and thirteen times the Sun's (mean) longitude respectively. 2 The mean motion of the sighrocca of Venus per solar day = ! 7022388 4320000 degrees (2-1/3-37/900) degrees-1/100 of a second. Hence the rule. A rule for finding the mean longitude of the sighrocca of Mercury: 36. Divide the grahatanu by 200: the result is in terms of signs. Then divide the grahatanu by 8: these are minutes. Then divide the grahatanu by 60: these are seconds. Adding all these (and also four times the Sun's mean longitude as prescribed in stanza 35) is obtained the (mean) longitude of (the sighrocca of) Mercury. ¹ Similar rules occur in BrSp.Si, xxv. 36 and SiDVṛ, I, i. 57 (ii). 2 See stanzas 32 and 36. 3 Similar rules occur in Br.Sp.Si, xxv. 34 and ŚiDVṛ, I, i. 50 (ii).
