DISCOVERY 



37 



comprehensive cosmological scheme of Dr. Harlow 

 Shapley. 



Since the opening of the century, various new 

 methods of determining the distances of stars have 



Dr. W. S. Adams, at Mount Wilson, found some years 

 ago that the intensities of certain lines in stellar 

 spectra depend on the absolute luminosity of the 

 stars, and as a result ho has been enabled to measure 



THE STARCI.OUDS OK THE GAI.A.KY IN THE DIRECTION" OF SERPENS AND SAGITTARIUS. 



(From a pkolograph by Pro/essor .Vax Wo!f.) 



been devised ; and in this way it is now possible to the distances of hundreds of stars by the spectro- 



speak with some degree of confidence of the scale on scope, and thus to add enormously to our knowledge 



which the universe is built. In the first place, Kapteyn, of exact stellar distances. Thirdly, Professor H. N. 



as early as 1901, indicated the possibility of ascertain- Russell, of Princeton, from his study of " eclipsing- 



ing the mean paraUaxes of groups of stars. Secondly, variable " stars, was able to ascertain the absolute 



