ANI> I >K FORMATION OF A THIN HLASTIC SHELL. 

 In evaluating the line-integrals we shall use the formula 



d-\ > a 33 



d.o o ,o, v o 



, a 

 **%= 



in which cfo is the element of the normal to the edge drawn as above stated. 

 9. From equations (15) we have 



, 



515 



(22) 





(23) 



so that 



ff/wsi TC \JQ fffw/ ) 9&r _L **\ ,( , dto> , 8r\"l 

 j j (M 8/3 - L 8m s ) rfS = j] [M (- / h ^ + J - L (- h, ^ + -JJ 



f (L/i - MX) 8u> ds. . f -r . . , . '. - '. . (24) 



Again, 



- 8 - (XU + pV} Sw - (XV- 





t, . . . . (25) 



by integration by parts. 

 Again, 



f f SWi dS 



ff/o 



= 1 J ( 2K * - 



<1<lfl . ff/ n 



M. + 1 J ( 2Xl ' 



3 u 2 



