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Sir Isaac Newton’s Book II.

toward a conjunction with the sun. But this conjunction willbe much forwarded by the visible motion of the fun itself.In the last scheme the fun will appear to move from S to-ward W. Suppose it appeared to have moved from S to \V,while the moon’s node has receded from B to V, then drawingsthe line \V T X, the arch V X will represent the distance of theline drawn between the nodes from the fun, when the moonis in V ; whereas the arch B A represented that distance, whenthe moon was in B. This visible motion of the fun is muchgreater, than that of the node ; for the fun appears to revolvequite round each year, and the node is near 19 years in mak-ing one revolution. We have also seen, that when the nodewas in the quadrature, the inclination of the moon’s orbit de-creased, till the moon came to the conjunction, or opposi-tion, according to which node it set out from ; but that af-terwards it again increased, till it became at the next node ra-ther greater than at the former. When the node is once re-moved from the quarter nearer to a conjunction with the fun,the inclination of the moon’s orbit, when the moon comesinto the node, is more sensibly greater, than it was in the nodepreceding ; the inclination of the orbit by this means moreand more increasing till the node comes into conjunction withthe fun ; at which time it has been shewn above, that the funhas no power to change the plane of the moon’s motion; andconsequently has no effect either on the nodes, or on the in-clination of the orbit.

4.1. As soon as the nodes, by the action of the fun, aregot out of conjunction toward the other quarters, they begin

again