MifcelUnea Curiofa. 313 



From thefe Four Propofitsons y all Queflions con- 

 cerning the Perpendicular Fall of Bodies, are easi- 

 ly Jolved, and either Time, Height, or Velocity 

 being aflign'd, one may readily find the other 

 two. From them likewife is the Doctrine* of 

 Projects deducible, afluming the two following 

 Axioms ; vi%. That a Body fet a moving, will 

 move on continually in a right Line with an equa- 

 ble Motion, unlefs fbme other Force or Impedi- 

 ment intervene, whereby it is accelerated, or re- 

 tarded, or deflected. 



Secondly, That a Body being agitated by two 

 Motions at a time, does by their compounded Farces 

 pals through the fame Points, as it would do, 

 were the two Motions divided and acted fucceffive- 

 ly. As for Inftance, Suppofe a Body moved in 

 the Line GF, (Fig. i. Tab. 5.) from G to R, 

 and there flopping, by another Impulfe, fuppole 

 it moved in a Space of Time equal to the former, 

 from R towards K, to V. I fay. the Body lhall 

 pafs through the Point to V, though thefe two 

 feveral Forces acted both in the fame time. 



Prop. V. The Motion of all ProjeSls is in the 

 Curve of a Parabola : Let the Line G R F (in 

 Fig> 1*) be the Line in which the ProjeB is di- 

 rected, and in which by the firft Axiom it 

 would move equal Spaces in equal Times, were 

 it not deflected downwards by the Force of 

 Gravity. Let G B be the Horizontal Line, and 

 G C a Perpendicular thereto. Then the Line 

 GRF being divided into equal Parts, anfwer- 

 ing to equal Spaces of Time, let the Defcents of 

 the Prcje ft be laid down in Lines parallel to G C, 

 proportioned as the Squares of the Lines G S, 

 GR, G L, G F, or as the Squares of the Times, 



