Page:The Mathematical Principles of Natural Philosophy - 1729 - Volume 2.djvu/468

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° T41 '* THE occaſion of the undertaking-was merely accidental; for he ſhewing me a paper which I communicated to the author, in the year 1717, relating td the motion of the nodes of the Moonls orbit; I recollected, that the method made uſe 'of in ſettling the Equation for that” .motion, ' was equally applicable to any other motion of revolution. And therefore I thought' that it would not be unacceptable to a reader of the Principia, to fee the uſes of the ſaid method explained in the other Equations of 'fthe Moon's rhotion: Eſpecially ſince the greateſt part of the Theory of the Moon is laid down without any proof; and ſince thoſe propoſitions, relating to the Moon's motion, which are demonilrated in the Principia, do generally depend upon calculations very intricate and abflrufe, the truth of which is not eaſily examined, even by thoſe that are moſt ſkilful; and which however might be eaſily 'deduced from other principles. But in my progreſs in this deſign, happening' to find ſeveral general propoſitions relating to the Moon's motions, which ſerve to determine many things, which have hitherto been taken from the obſervations of” Aflzronomerſz And I . having