nomena. That astronomy, 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 contraction 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
