quibiis fubflitutis prodibit 



H-^ol(( I -hx){in.icol'.r-j fm.idn.r) 

 vnde vicifTm colligitur 



</ X f;n. i fin. ^ - ^ Y fin. i cof. ^ -h ,/Z cof i — tfz 



— ( I -^x)d^fm. i cof r -|-j d^ fin. i fin. r. 



$. 9. Ante autem quam ad difFerentialia fecnnda 

 defcendamus conducet diiferentialia dX, dY, d Z per li- 

 teras minusculas exprimere. Cum igitur fit 



X — m{i-\-.v^) — vj'-i~z fin. 1 fin. ^ 

 erit difF^-rentiando 



dX — md.x — vdjf -H d z, fin. i fin. J^ 



4- dQ, [z fin. i cof S^+M-J-» (i-f-A:}) -^/r^wy+v (i+jr), 

 Eodem modo (ecunda aequatio 



Y — n{i H-jr) — \i.y — 5; fin. 1 cof ^ 

 difTerentiata praebet 



dY — nd X — (X dy — dziin. icof. ^ 



4-V^(2:fin.ifin.^ — v^ + /«(i+jf)) — ^/r^wj^-f/x^i-fjr). 

 Denique tertia aequatio 



Z — (i-{-x) fin. t fin. r -\-y fiu. i cof r -f- « cof. 1 

 difFerentiata dat 



d Z — d X dn. i fin. r -\- dy fin. 1 cof r -\- d z cof 1 



<jf r fin. i ( ( I -I- jr ) cof. r —y fin. r). 



§. JO. His praeparatis progrcdiamur ad difFeren- 

 tio-differentialia; vbi primo notandum efl: quia anguli r 

 et ^ funt tempori proportionales, eorum difFerentialia d r 

 et ^S^ pariter effc conflanda, perinde atque elementunti 

 temporis d t. Hinc primam cuoluamus aequationem §. 6, 

 datam , quac erat : 



