Smithsonian Report, 1930.— St John 



Plate 4 



1. Zeeman effect given by the Fe line 6,173 in the laboratory at A and in sun spots at B. 

 The line by which the magnetic fields in sun spots are usually measured. 2. Horizontal 

 cross section of a high-level vortex photographed in the red light of hydrogen at a height of 

 8,000 kilometers. To be studied in connection with the vertical section, Figure 1 of text 



