500 



400 



300 



200 



100 



...x.^.g, 



/ 



f 





o 





\ 





O 





466 



O 





I 



D 

 00 





o 



57' 









o 







V 





J 



Fig. 4. 



i/Ae fcdling of f o1 : ' tbub fields at points 

 p cujoe^ oftfrce, ccrvruxtuT'ee . 



















L 





£ 













I 





3- 













i5 



40" 



45 



50" 



