( .^77 ) 



line 5771. Tlie amount can oasily ho uiven in A. V. The cliange of 

 (t — h aniounls lo 0,()2o ni.ni. in ihc siron,L'est- liehl of 23470 (laiiss. 

 Half this amount determines the change of wavelength. It becomes 

 0,007 A. U., the distance of two orders of the echelon == 1.1J6 m.m. 

 corresponding to 0,689 A. U. 



5. The simplicity of the results obtained by means of the method 

 of ^ 4 is considerably diminished by the fact, that line 5770 under- 

 goes a change of wavelength as well as line 579J . The sensibility 

 of the method for discovering relative changes of wavelength is very 

 clearly seen by a comparison of the two columns under a — a'. 



In order however to be sure of a simple interpretation of results 

 and also on account of gain in the intensity of the light I returned, 

 the reality of a change of wave-length being now rather evident, to 

 the arrangement as it is most commonly nsed. The slit of the auxiliary 

 spectrosco})e is then parrdlel to that of the echelon. 



The results obtained for the yellow mercury lines are given in 

 the table. 



The observations recorded in the last three columns have been 

 taken with other orders of the echelon, rf, gives in A. U. the change 

 of wavelength by magnetization. The largest change observed is one 

 of 0.009 A. U. recorded on plate 164 for a field of 24400 Gauss. 



The evidence from these experiments tends to confirm those obtained 

 in § 4. 



The separate numbers show some discrepancies which needs a 

 discussion, which will be given later on. Before proceeding further, 



