CH. x.] ZEEMAN EFFECT 115 



being a complete and satisfactory theory, unless the 

 projected motion happen to be circular ; but it was a 

 brief and early attempt. 



An instructive and interesting method of demon- 

 strating the Zeeman effect was devised by W. Konig 

 and described in the Jubilee volume of Wiedemann's 

 Annalen, 1897, of which a brief abstract is given in 

 Nature, vol. 57, p. 402. An emission flame con- 

 taining the salt under examination is placed in a 

 strong magnetic field, and viewed through an absorp- 

 tion flame, containing the same salt, by means of a 

 doubly-refracting prism, or other double image instru- 

 ment, so as to get two images of the emission-flame 

 side by side. On exciting the magnet, the emission 

 frequency, of vibrations perpendicular to the lines of 

 force, is put out of tune with the absorption frequency, 

 and accordingly the amount of absorption is much 

 diminished. The result is that one of the images 

 brightens up every time the magnet is excited ; the 

 other image, which corresponds to vibrations along 

 the lines of force, remaining unchanged and constitut- 

 ing a convenient standard of brightness. 



