VSS. 23-30] GRAPHICAL REPRESENTATION 71 should be kept separately and laid off one after the other in the projected figure. A rule relating to the valana for the middle of the eclipse : 21. The (resultant) valana for the middle of the eclipse ob- tained in the same way as for the first contact without any further addition or subtraction of the Moon's latitude is the corrected {valana for the middle of the eclipse). The direction of that (Moon's latitude) is to be taken reversely (in the projection of a lunar eclipse). 1 What is meant is that the valana for the middle of the eclipse (which is calculated according to the rule stated in stanza 18) should not be combined with the Moon's latitude for that time (although such a rule is given in stanzas 19-20). The two quantities should be kept separately and laid off one after the other in the projected figure in the manner prescribed in stanzas 23-30 below. The latter part of the stanza says that in drawing the figure of a lunar eclipse, the direction of the Moon's latitude is reversed. That is, when it is north, it is taken as south; and when it is south, it is taken as north. The rea- son is that in the case of a lunar eclipse, we find the position of the shadow with reference to the Moon; and when the Moon is north of the ecliptic (i.e., when the Moon's latitude is north), the shadow is to the south, and vice versa. A rule for converting minutes of arc into ahgulas : 22. The minutes of arc of the diameters of the Sun, Moon, and the shadow and those of the (Moon's) latitude and the (cor- rected) valana when divided by two are reduced to ahgulas, (But when the Sun and Moon are) on the horizon, they (i.e., minutes of arc) are the same (as ahgulas)? A rule relating to the construction of the figure of an eclipse : 23-30. Draw a circle with a thread equal in length to half the ahgulas of the diameter of the eclipsed body (as radius) and another (concentric circle) with a thread equal in length to half the sum of the diameters k the eclipsed and eclipsing bodies. 1 Cf. MBh, v. 54, 77. 2 Cf. MBh, v. 53(ii).
