Mifiellanea Curio/a. 1 7 



manner, are here proved to defcribe fuch Figure^ 

 as anfwer punctually to ail that the Induftry of 

 this and the laft Age has obferved in the P aie- 

 tary Motions. So that it appears, that there is 

 no need of folid Orbs and Intelligences, as the 

 Antients imagin'd, nor yet of Vortices or Whirl- 

 pools of the Cceleftial Matter, as Des Cartes flip- 

 pofes ; but the whole Affair is fimply and me- 

 chanically performed, upon the foie Suppofition 

 of a Gravitation towards the Sun ; which cannot 

 be denied. 



The Motion of Comets is here fhewn to be 

 compounded of the fame Elements, and not to 

 differ from Planets, but in their greater Iwifmefs, 

 whereby overpowering the Gravity that fhould 

 hold them to the Sun, as it doth the Planets, 

 they flie off again, and diftance themfelves from 

 the Sun and Earth, fo that they fbon are out of 

 our fight. And the imperfect Accounts and Ob-' 

 iervations Antiquity has left us, are not (ufficient 

 to determine whether the fame Comet ever re- 

 turn again. But this Author has fhewn how 

 Geometrically to determine the Orb of a Comet 

 from Obfervations, and to find his Diftance from 

 the Earth and Sun, which was never befoiC 

 done. 



The third thing here done is the Theory of 

 the Moon, all the Inequalities of whole Motion 

 are proved to ari/e from the fame Principles* 

 only here the effect of two Centers operating 

 on, or attracting a projected Body, comes to he 

 confidered ; for the Moon, though principally ac- 

 tracked by the Earth, and moving round it, does 

 together with the Earth, move round the Sun 

 once a Year, and is, according as fhe is nearer 

 or farther from the Sun, drawn by him more 

 or lels than the Center of the Earth, about 

 C which 



