Sir Isaac N e w t o n’s Book II.

286

10 . I11 the firft cafe the waters, like the body whichthey equalled in velocity, by the action of the moon wouldbe brought nearer the center under and oppofite to the moon,than in the parts in the middle between thefe eaftward orwe ft ward. That fuch a body would fo alter its diftance bythe moon’s aeftion upon it, is clear from what has beenmentioned of the like changes in the moon’s motion caufedby the fun a . And computation fhews, that the differ-ence between the greateft and leaft diftance of .fuch a bodywould not be much above 4 - feet. But in the fecondcafe, where all the parts of the water preferve the fame fttua-tion continually in refpedt of the moon, the weight of tholeparts under and oppoftte to the moon will be diminifhedby the moon’s aeftion, and the parts in the middle betweenthefe will have their weight increafed : this being effe&edjuft in the fame manner, as the fun diminifhes the attraefti-.011 of the moon towards the earth in the conjunction andoppolition, but increafes that attra&ion in the quarters.For as the ffrft of thefe confequences from the fun’s ac-tion on the moon is occaffoned by the moon’s being at-tracted by the fun in the conjunction more than the earth,and in the oppofition lefs than it, and therefore in thecommon motion of the earth and moon, • the moon ismade to advance toward the fun in one cafe too faft, andin the other is left as it were behind; fo the earth willnot have its middle parts drawn towards the moon fo ftrong-ly as the nearer parts, and yet more forcibly than the re-moteft : and therefore ftnee the earth and moon move each

* § 8 .

month