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THE MOON’S CHANGES

joining the cusps will only be inclined about twenty-eight degrees to the horizon. But next, suppose thatthe moon at this time is at her greatest distancenorth of the ecliptic, or at M 2 , five degrees from theposition Mu and about the same distance as in theformer case from the sun. Then the great arc-circleS M 2 from the sun to the moon is inclined ten or moredegrees (according to the moon’s age) to S M 1; andthe line joining the cusps is, in this case, inclined lessthan 18° to the horizon. Indeed, when the moon isvery young, the angle M, S M 2 is considerable. HenceS M 2 makes a considerably larger angle with thehorizon than S M u and the line joining the cusps is,as shown in the figure, much more nearly horizontal.A very young moon seen soon after sunset, underthese circumstances, may have the line joining itscusps quite horizontal, or even have the northerncusp lower than the southern.* Like considerationsapply to the case of the old crescent moon,f beforesunrise, soon after the autumnal equinox.

Next, however, suppose the western part of the

* It is hardly necessary to say that the exact angles for anyposition can be quite readily calculated ; but the matter is not ofsuch a nature as to require the introduction of such calculationshere. The student acquainted with the elements of spherical tri-gonometry may find interesting and not uninstructive occupationfor a leisure hour or so in considering a few cases. The angleM 2 S M, is more than 10° when the moon is less than one-eighthfull, or halfway to the first quarter.

t The word crescent here means merely crescent-shaped, notcrescent in the sense of increasing.