FORMVL. DIFFERENTIALIVM. 1S7 



formulae iudicium inftitui debet. Vt vero eiiiden- 

 tius pateat , quaenam aequationes ex euolutione valo- 

 rum ipfcrum w, tt, 71', tt'', k, yJ etc. oriantur ; 

 fequentes aequalitates annotafle Ytile erit : 



_ , d\ ddO dV ^ 



■ /k' ^<y d? 



Vlir (,-S^U=:«)-(f )4-N 

 ^dxdjdz ^ dy ^ ^dy 



A a a IX. 



