-3==! ) 54 ( 



lium ipfius z euanefcentes ponantur, vti feqncnte fche- 

 mate illuftrabitur: 



+ {j.'y 



+ fJL'5'. 



Hinc fit 



^ + X'=:o; 2(3 + 5+Xp + X'(2+(3) + p.' = o; 

 X((3 + ^)+tx(3 + X'((3' + 5') + fx',3' = o; p.5 + {x'^'z:o; 

 quibus aequationibus omoino fatisfit, ponendo 



X' = - (3 ; X =: H- (3' ; fx' zr - 5 ; |jl z= + 5'. 

 His autem valoribus ipforum X, X', jji., p.' in coefficienti- 

 bus difFerentialium ipfius y lubftitutis, prodibit i(U ae- 

 quatio ; 



X' d'y + {A;-\-o--V^')xWy 



+ (2 + 2 (a + (3') + y + ^' + a(3'-a'(3) x'ddy 

 + (a (3' - a' p + a 5' - a' ^ - P y ' + (3' y) X ^^ 

 + (y S^-y^^^jVzz o, 



quae iam eft formae fupra propofitae. 



§. 3. Procedamus nunc ad binas aequationes dif- 

 ferentiales tertii gradus: 



I. x^ d'y -i-ax* d dy^Y X dy -{- ey -\-^ x" dd z 

 •^'Zxdz-^-^z^izOf 



II. 



