Phil. Mag. Ser. 6, Vol. 19, PI. III. 















Fie 



4. 













60° 







































/ 













50° 















/ 





































10° 





0K 



(JIT/IBLL 



OSE/ft 



FOR 





h 



7 







s 













tV£ 



SWN C 



21. 



\ 1 c 







TABLE 



FOR 



Q / 









30° 









i 





Wl 



'sro/vc 



M. 



S L 















V 



'i 







i 



7 ^ 









20° 

















\ 1 



ID 



U/VSU/Ts 

 USE 



W£STL 



IBLEfO 

 //V 



WCflL 



f 



























10° 







1 

































/ 













0° 







1 





P£/fCL 



a/t/igl 



<?/- c 



9/DM/U 



V 



































\l 



16 



£0 



