124 



fd p\ (^ ^\ ,dèz\ ,3dz\ /ddz 



z\ ,ddz\ . 

 /ddz\ ,ddz \ _ 



'^ox' \ày' \ày' ^âx^ yày- '■dv- ^ôv' ^ày' 



\dx> \3iJ {d\J \dx^ — ^ \Tx^) \dx^J \d^dV ') 



\ôx^\dv/ \dv'ydxy \dy'\dvJ VdJ\dy' '^dxdy' ^dv''' Kdydv^ \èxdvJ ^ 



/3.7\ ,9 r-. ,d7.N .9rx i^^^\ /9 9 zn ^ 3 9 z n^ 



L'équation deviendra donc : 



tn ('^ ^ _ h i'^'^') -i- rf^'^^^ ( ~~ ^^* ^^y ^'*^' ~^ ^^^ ^^^ ^^'^' ~*~ ^^^ ^^ ^y 



\ yav' \dxJ \dy^ "^ \dv^ \dy/ \dxJ \dy^ ^dv/ ^dx^y 



+ (A-r-A^z--az)((^5(^;)-0(|;:)) 



A^.--cz-.«)((^])(|,p-(^;)(^;:)) 1 



'^^;/- 



„ + (C'''Z'-C^Z''''+A 



" + B^,n--B-m^-.b m) (f^D ^ _ (^^ (^^ 

 4_(CW-C'W^-BV-BV-' ■ -'- /..,^/.'^■' 









o. 



