2* 



the sun. If positive or negative electrons were 

 caught and whirled in a vortex they would produce 

 a magnetic Held, such as we obtain by passing an 

 electric current through a coil of wire. Zeeman 

 had discovered in 1896 that the lines in the spec- 

 trum of a luminous vapor in a magnetic field are 

 widened or (if the field is strong enough) split into 

 several components (Fig. 21). Moreover, the light 



FIG. 21. Effect of Magnetic Field upon Lines of Iron Spectrum In 

 ii the middle component and in /> the outer components are cut 

 out by a Xicol Prism; (~, Spectrum without Magnetic Field. 



of these components is polarized in so characteristic 

 a \vay that there can be no uncertainty in identi- 

 fying the effect. Could this be the condition of 

 things in sun-spots? 



The jo-foot spectrograph of the tow r er telescope 

 permitted the test to be made at once. The 

 characteristic polarization phenomena appeared 

 and one by one all of the distinctive peculiarities 

 of the Zeeman effect were made out. Thus direct 



