1889.] On the Spectrum of the Great Nebula in Orion. 43 



Phoho^rapk of 



882. 





• 



> 



e * 





• 





Phol~ocjraph oj 



888. 





® 





• • 









Photograph of I889. 



< 



© 



V 











line to unite with a line near it, and that in 1882 I measured the 

 middle of the broad band produced by the union of the wide images 

 of two lines. Its position is about six tenth-metres more refrangible. 

 It does not therefore agree, as I then suggested, with the hydrogen 

 line £ in my spectra of white stars. A statement of the position of 

 this line relatively to the magnesium-flame triplet will be given 

 further on, when I come to discuss the comparison of this spectrum 

 with that of the nebula. 



