EVOLUTION IN THE SUNS 75 



of years. The order of evolution of the 

 elements would thus happen in the same 

 fashion as the origin of organic species in the 

 geological epochs. In geology the range of 

 temperature is infinitely shorter, and the 

 gradient of fall of temperature slower, so 

 that some millions of years witness but the 

 fall of a few degrees in temperature. 



The names for the stellar epochs are derived 

 either from that of a typical bright star which 

 possesses at the present time a temperature 

 indicated by its spectrum, or sometimes the 

 name of the constellation in which the star is 

 found. Where two columns of names of stars 

 are given those in the first column are stars 

 of which the temperature is at present 

 supposed to be increasing, and where evolution 

 would be reversed or in the direction of dis- 

 integration. The second column contains 

 stars with decreasing temperatures, where 

 elemental evolution towards higher atomic 

 weights is progressing. Our own sun would 

 be placed in this column at the level denoted 

 by Arcturian. 



The word proto-hydrogen in the table 

 indicates that in these hottest of all observed 

 suns (two suns in the constellation Argo), 

 a series of lines are met with belonging to no 

 known terrestrial element, but standing in 



