p. ZEEMAN. "Observation of the magnetic resolution of the spectral lines 

 by means of the method of Fabry and Perot." 



1. The yellow mercury lines in mag- 

 netic field. Very wide slit. Green 

 mercury line overexposed. 



2. The same lines. Narrow slit for 

 measurement of the yellow mercury 

 lines. 



Proceedings Royal Acad. Amsterdam. Vol. X. 



