68 B. E. Moore 



ADDENDUM 



Zeeman {Science Abstracts, vol. 12, p. 155) confirms the re- 

 sults of Gmelin ( /. c. ) for Mercury line 5791. Purvis (Proc. 

 Lamb. Phil. Soc, vol. XV, part I) records a displacement of sev- 

 eral lines in the magnetic field toward the red. I had suspected 

 such a change when watching lines under the microscope while 

 an assistant turned the magnetic field current on and off, but had 

 not followed it up with quantitative measurements. This could 

 scarcely be identical with the results of Jack (/. c). It would 

 seem, rather, to be analogous to a pressure shift of the lines. H. 

 Xagaoka and S. Amino (Science Abstracts, vol. 12, p. 155) have 

 studied a few spectral lines with very weak fields. They find 

 some unsymmetrical lines, with the red component stronger and 

 least displaced. These displacements plotted against the mag- 

 netic field give a hyperbola. Beyond 5000 Gauss the separation 

 is proportional to the field strength and the intensities of the op- 

 posite components are equal, i. e. the lines are then altogether 

 symmetrical. This experiment is a signal confirmation of the 

 Yoigt theory. It suggests, too, as stated in previous pages, that 

 the dissymmetries herein recorded are different in character and 

 origin. We have, then, the following irregularities in the "Zee- 

 man Effect"' : first, a displacement as noted by Purvis ; second, the 

 "Yoigt Effect" developed from the dispersion equations, noted 

 by H. Xagaoka and S. Amino ; third, a variation in displacement 

 proportional to the square of the field strength, first observed by 

 Gmelin ; fourth, a displacement proportional to the field strength, 

 observed by the author. Some of these are different multiples of 

 small values ; fifth, an irregularity arising from the splitting of 

 one of the symmetrical components, also observed by the author. 

 Ions acting or "linked" together might produce results similar 

 to the third and fourth, as shown bv Yoigt and Ritz. 



156 



