Magnetic Separations of tlie Lines of Iron, Nickel and Zinc in Different Fields. 63 



The discrepanc}^ of the value obtained by Miller from that 

 here given is about 10%, but the simultaneous and accurate 

 determination of magnetic fields leaves no room for doul^t as to 

 the value here given. (Plate XX, Fig. 2). 



Summary. 



The object of the experiment was to investigate whether the 

 separations of iron and nickel lines are proportional to the fields 

 applied. For measuring the strength of the fields, the zinc line 

 -i: 4680*138 was adopted, as the separation of the line has been 

 accurately determined by man}^ observers. In groups "g", 

 " h " , ' i " and " j " , this line ivas simultaneously photographed 

 on the same plate with iron and nichel lines. The simultaneous 

 photography, however, limited the number of lines to be studied, 

 consequently I was obliged to photograph this line l^efore and 

 after the photography of iron lines (groups " e " and " f "). 



Concave grating was used for obtaining spectra of the lines 

 from the second to the fifth order. 



The sharp triplets show separations of their outer two com- 

 ponents proportional to the fields applied ; but in the case of most 

 of the diffuse triplets, these separations are not proportional to the 

 fields; in some diffuse lines, -^ is constant in weak fields but 

 becomes larger in the stronger; in other diffuse lines, the devia- 

 tions from the mean are too large to assume -g- as constant. 

 Arthur King observed these lines with larger grating and took 

 these diffuse triplets for more complicated separated lines. 



In the course of investigation, the range of spectra photo- 

 graphed was taken as wide as possible at single fields. The 

 results thus obtained are compared with the published data. 



-^:3345'13 of zinc is also measured in different fields. The 

 separation of this line is linearly proportional to the fields. 



