\ /3s \ dV 



:/x R = * + \ 3x r/x r = * dx c 



a ^ v ' + N R 2 /d^y| i4 



4 \dx 



(132) 



Similarly the differential arc length along the orthogonal 

 surface coordinate is 



/ 3 s \ d k 1 9 s \ 



\ 9x c/x ,-k dx R + \ 9x r/x -« 



dXr 



(133) 



(134) 



h, (/c d« \ 2 1+N R 2 W 



+ a + 



D \D dx R / 



(135) 



22 



