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

 ° T41 '* THE occaion of the undertaking-was merely accidental; for he hewing 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 ue 'of in ettling 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 ues of the aid method explained in the other Equations of 'fthe Moon's rhotion: Epecially ince the greatet part of the Theory of the Moon is laid down without any proof; and ince thoe propoitions, 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 eaily examined, even by thoe that are mot kilful; and which however might be eaily 'deduced from other principles. But in my progres in this deign, happening' to find everal general propoitions relating to the Moon's motions, which erve to determine many things, which have hitherto been taken from the obervations of” Aflzronomerz And I. having