3910.] RESEARCHES IX COSMICAL EVOLUTION. 221 



If with the modern improvements in the mathematical treatment 

 ■of the problem of three bodies, and the observational data derived 

 from photographic study of the nebulje and clusters, as well as from 

 the visual and spectroscopic binary stars, this progress be not pos- 

 sible in our time, it is difficult to see how better results can be 

 •expected in the future. 



I have therefore labored with no ordinary energy to weave 

 together the scattered and discordant threads of argument regard- 

 ing phenomena which heretofore could not be brought into har- 

 monious relationship. And I have been fortunate enough to attain 

 an unexpected degree of success ; so that I cannot doubt that the 

 result will go far towards a permanent solution of the problems 

 of cosmical evolution, which is certainly an urgent desideratum of 

 our time. 



U. S. Naval Observatory, 

 Mare Island, Californl\, 

 April 8, 1910. 



