OF ASPECT, ROTATION, AND LIBRATJON. 145

ecliptic, at its least inclination to the horizon, soonafter sunset, or the time of year shortly before theautumnal equinox. The state of things is that illus-trated in fig. 50, Plate XII. Then in our latitudesthe inclination of the ecliptic to the horizon is about15 degrees, and supposing the moon on the eclipticand young, as at M 3 , the line joining the cusps will beinclined about 75 degrees to the horizon. But sup-pose the inoon, as at M 4 , at her greatest distancesouth of the ecliptic, or five degrees from the positionM 3 , and about the same distance from the sun, thenthe great circle S M 4 from the sun to the moon is in-clined more than ten degrees to SM 3 ; and the linejoining the cusps may be much more nearly uprightthan when the moon is as at M 3 . But this linecannot be actually upright when the sun is below thehorizon, for the line must always be square to thegreat circle through the sun and moon, and, of course,when the moon is above and the sun below the horizon,this great circle is inclined to the horizon, and a lineperpendicular to it is correspondingly inclined fromthe vertical. Similar considerations apply to the caseof the old crescent moon before sunrise, soon afterthe vernal equinox.

We see, from these extreme cases, that the linejoining the moon’s cusps can have every inclination,from being nearly vertical to a horizontal position,and even that the northern cusp may be below thesouthern, according to the season of the year and themoon’s position in her orbit. So that, to assert that

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