Toy & GrHosii. 



Phil. Mag, Ser. 6, Vol. 40. PL XVIL 



Fiff. 2. 





Fig. 3. 







i 







is 











cr 



*o 







<« 



II 







n 



< 







/< 



1 I 1 i l I i l 

 i I i l i i 1 l 



M LKHGFE D 



i i i 

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C BA 



Ratio of Intensities=23 : 1, 



Fig. 4. 



