§. 10. Sin aiitem iftiid elemcntum cnruae ds con- 

 ftans accipere velimus , erit d s d d s :=:z o^ ideoque dxddx 

 -hdy d dj ~ o^ ex qua aequatione fit primo d dj ziz- i^JJj^ , 

 ideoque denominator ille d x d dj -djdd x fiet --^J5I^±^ 

 zzz. — ^J-All . ficque hoc cafu radius ofculi erit =: — -•'^''^. 



^. II. Simili modo cum fit ddxzrz—tZJJJ' cric 

 dcnominator 



dxddy-djddx=z liill^Ji^yl} — ^iii 9^ , 



• a X o X 



vnde radius ofculi collioitur ~^^^^^. Hoc modo fumto cle- 

 mento ds confliante duae habebuntur formulae pro radio ofcu- 

 Ji, quae funt — iLp ct i±if . 



OBSKR- 



