An account of Sir Isaac Newton's philosophical discoveries : in four books / By Colin Maclaurin ... Published from the author's manuscript papers, by Patrick Murdoch.

  • MacLaurin, Colin, 1698-1746
Date:
M.DCC.XLVIII. [1748]
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Licence: Public Domain Mark

Credit: An account of Sir Isaac Newton's philosophical discoveries : in four books / By Colin Maclaurin ... Published from the author's manuscript papers, by Patrick Murdoch. Source: Wellcome Collection.

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    need only consider the excefs of the adion of the fun on the earth above its adion on the moon, and we muft confider this excefs as drawing the moon from the earth, in this place, in a diredion oppofite to the former, that is, towards the place op- pofite to where the fan is ; becaufe we consider the earth as qui- efcent, and refer the motion, and all its irregularities, to the moon. In the quarters, we confider the adion of the fun as adding fomething to the gravity of the moon towards the earth. 5. Suppofe the moon fetting out from the quarter that pre¬ cedes the conjundion, with a velocity that would make her defcribe an exad circle round the earth, if the fun’s adion had no effed on her ; and becaufe her gravity is increafed by that adion, fire muft defcend towards the earth, and move within that circle : her orbit, there, will be more curve than other- wife it would have been ; becaufe this addition to her gravity will make her fall farther at the end of an arc below the tan¬ gent drawn at the other end of it; her motion will be accele- rated by it, and will continue to be accelerated till me arrives at the enfuing conjundion; becaufe the diredion of the adion of the fun upon her, during that time, makes an acute angle with the diredion of her motion. At the conjundion, her gravity towards the earth being diminifhed by the adion of the fun, her orbit will be lefs curve there, for that reafon ; and fhe will be carried farther from the earth as fhe moves to the next quarter ; and, becaufe the adion of the fun makes then an obtufe angle with the diredion of her motion, fhe will be re¬ tarded by the fame degrees by which fhe was accelerated before. 6. Thus fhe will defcend a little towards the earth, as fhe moves from the firft quarter towards the conjundion, and afcend