2i^ Sir Isaac Newton’s Book II.

os such a touching plane, we must here make use os what isequivalent,, the plane PKQ,, with which the line BKL shallmake a lest angle than with any other plane; for this planedoes as it were touch the line B K in the point K, since it socuts it, that no other plane can be drawn so, as to pals be-tween the line B K and the plane P K Q; But now it is evi-dent, that the point P, or the node, is removed from M to-wards G, that is, has moved yet farther forward; and it islikewise as manifest, that the angle under K PG, or the in-clination os the moon’s orbit in the point K, is greater thanthe angle under I MG, for the reason so often assigned.

37. After the moon has passed the quarter, the path ofthe moon being concave to the plane AGCH, the nodes, asin the preceding cafe, shall recede, till the moon arrives atthe point L ; which shews, that considering the whole timeof the moon’s passing from B to L, at the end of that time thenodes shall be sound to have receded, or to be placed back-warder, when the moon is in L, than when it was in B. Forthe moon takes a longer time in passing from K to L, thanin passing from B to K ; and therefore the nodes continue torecede a longer time, than they moved forwards; so that theirrecess must surmount their advance.

58. In the lame manner, while the moon is in its pa stagefrom K to L, the inclination of the orbit shall diminish, tillthe moon comes to the point, in which it is one quarterpart of a circle distant from its node ; suppose in the pointR ; and from that time the inclination shall again increase.

Since