238 POPULAR SCIENCE MONTHLY. 



nomena. That astronom} r , geology, physics, chemistry, physiology and 

 all the rest were independent departments of knowledge and that each 

 could be worked out completely without help or hindrance from others. 

 The great contributions of the nineteenth century showed they were 

 all of one family, and the surprise as one after another were thus 

 linked was only paralleled by the hostility manifested in many quarters 

 to such a claim. Together they show strongly that the knowledge was 

 so unexpected and so new that it was not easily assimilated. Especially 

 was this true when the new implications made it needful to abandon 

 much in philosophy and religion that had been held to be unassailable. 

 Many heated battles were fought, but science was always victorious and 

 never had to surrender a field once entered. 



What these triumphs were has often been presented within a year 

 or two, and the recital of them has raised the query in many minds 

 whether there can possibly be left much of importance to be discovered. 

 Alexander conquered the world and wept because there was no more 

 Alexandrine work to do. He must go home and mope the rest of his 

 life. Inactivity is an intolerable idea to an energetic man with but 

 one idea. Heaven saved Alexander from a long endurance of such 

 idleness as he feared, by removing him when his work was done. 



Is there no more work for the man of science ? Are there no more 

 problems of importance awaiting the investigator? Have we all the 

 knowledge we are likely to get? There are some who, having noted 

 the prodigious product of the nineteenth century, have half feared that 

 science has been worked out. 



That this is not true I will endeavor to show. 



Beginning with astronomy. We are well assured now that the 

 earth as a part of the solar system has had a long history. That all 

 these bodies have reached their present conditions and relations by 

 a process of growth taking millions of years. The same factors that 

 have been active in the past are still operative, producing changes in 

 magnitude, in distances, in temperature and the like. The moon, once 

 a corporate part of the earth, has left it through tidal action and will 

 move still farther away for something like fifty millions of years, after 

 which it will return. The sun is a mass of gas, which by its contrac- 

 tion through gravitation has become exceedingly hot, and is radiating 

 its energy away at a definite and known rate. As it is limited in size 

 and amount of material, one may without difficulty calculate that the 

 supply of heat from it will last about ten millions of years. It will 

 cease to shine and become cold unless something like a catastrophe 

 shall reendow it with high temperature and larger volume, when it 

 may repeat the history of these millions of years past. The same 

 conditions of contraction and rise in temperature are observable in 



