Suppofition \ whereby he finds the genuine" 

 Caufe of the feveral Appearances in the Theo- 

 ry of the Moon and Planets, and difcovers the 

 hitherto unknown Laws of the Motion of Co- 

 mets, and of the Ebbing and flowing of the Sea. 

 Each of which are Subjects that have hitherto 

 taken up much larger Volumes ; but Truth 

 being uniform, and always the lame, it is admi- 

 rable to obferve how eafily we are enabled to 

 make out very abftrufe and difficult Matters, when 

 once true and genuine Principles are obtain d : 

 And on the other hand it may be wondred, 

 that, notwithftanding the great facility of truth, 

 and the perplexity and non confluences that al- 

 ways attend erroneous Suppofition s, thefe great 

 Difcoveries mould have efcaped the acute Difc 

 quifitions of the beft Philofophica) Heads of all 

 paft Ages, and be referv'd to thefe our Times, 

 But that wonder will fbon ceafe, if it be con- 

 fider'd how great improvements Geometry 

 has receiv'd in our Memory, and particularly 

 from the profound Difcoveries of our incompa* 

 rable Author. 



The Theory of the Motion of the primary 

 Planets is here (hewn to be nothing elfe, but the 

 contemplation of the Curve Lines which Bodies 

 caft with a given Velocity, in a given Direction, 

 and at the fame time drawn towards the Sun 

 by its gravitating Power, would defcribe. Or, 

 which is all one, that the Orbs of the Planets 

 are fuch Curve Lines as a Shot from a Gun de- 

 fcribes in the Air, being caft according to the 

 direction of the Piece, but bent in a crooked 

 Line by the fupervening Tendency towards the 

 Earths Centre : And the Planets being fuppofed 

 to be projected with a given Force, and at- 

 tracted towards the Sun, after the aforefaid 



man* 



