212

Sir I s a a c Newton’s Book If*

33. Let AGCH (in fig. 1 o 3.) be a circle described in theplane of the earth’s motion, having the earth, in T for its center-Let the point opposite to the fun be A, and the point G a fourthpart of the circle distant from A. Let the nodes of the moon sorbit be situated in the line B T D, and B the node, falling be-tween A, the place where the moon would be in the sthhand G the place where the moon would be in the quarterSuppose B E D F to be the plane, in which the moon essays t°move, when it proceeds from the point B. Because the m° 011in B is more distant from the fun than the earth, it shall t eless attracted by the fun, and shall not descend towards thefun so fast as the earth: consequently it shall quit the plafl eBE OF, which we suppose to accompany the earth, and De-scribe the line BIK convex thereto, till such time as it coiU eSto the point K, where it will be in the quarter: but st 0111thenceforth being more attracted than the earth, the m o° lJshall change its course, and the following part of the p at ^it describes shall be concave to the plane BED or B6^'and shall continue concave to the plane B G D, till it cro$" eSthat plane in L, just as in the preceding cafe. Now Iwhile the moon is pasting from B to K, the nodes, contra 1 ^to what was found in the foregoing cafe, will proceed f° rward, or move the fame way with the moon a ; and at th 6fame time the inclination of the orbit will increase b .

34. When the moon is in the point I, let the pl aIlCMIN pass through the earth T, and touch the path of & e

* Vid. Newt.Princ. Lib.III prop 30 . p. 440 i. * Ibid. Lib. I. prop. 66 . coroll- < 0 '