FIG. 9. ZEEMAN DOUBLET PHOTOGRAPHED IN LABORATORY SPECTRUM. The 

 middle section shows the doublet. The adjacent sections indicate the appear- 

 ance of the spectrum line in the absence of a magnetic field. 



FIG. ro. a, b, spectra of two sun-spots. The 

 triple line indicates a magnetic field of 4500 

 gausses in a, and one of 2900 gausses in b. 



