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venture to depart from it too far, in eſtabliſhing equations entirely new; ſince I am well affured, upon the beſt au- thority, that it is never found to err more than feven or eight minutes. And therefore, hoping that the rea- der, who confiders the ſudden occafion and neceffity of my publiſhing theſe Pro- pofitions at this time, will make due allowance for the want of order and me- thod, and look upon them only as fo many diftinct Rules and Propofitions not con- nected: I ſhall begin, without any other preface, with fhewing the origine of that inequality, which is called the Va riation or Reflection of the Moon.
The Variation of the Moon. THE variation or refle- ction is that monthly in- equality in the Moon's mo- tion, wherein it more manifeftly differs from the laws of the motion of a pla- net in an elliptic orbit. Tycho Brabe makes this inequality to arife from a kind of libratory motion backwards and forwards, whereby the Moon is accelerat- ed and retarded by turns, moving fwifter in the firſt and third quarter, and flower in the fecond and fourth, which inequali-. ty is principally obſerved in the octants.
Sir Isaac Newton accounts for thevariation
