DAILY INFLUENCES OF ASTRONOMY — CAMPBELL. 147 



let it go at that? This selfish spirit, if applied to all subjects, would 

 retrograde our civilization. Even the possession of the truth is not 

 so potent for good as the desire to know the truth and the struggle 

 to discover it. Practically, a knowledge of the origin of the sun's 

 heat may be the key for locking up great quantities of it on summer 

 days and unlocking it when and where needed. 



Who is not interested in Mars, a planet much smaller than the 

 earth, a little over four thousand miles in diameter, which revolves 

 around the sun in somewhat less than two years, at an average 

 distance from the sun 50 per cent greater than the earth's distance? 

 Mars is literally one of the earth's brothers, and we should be sin- 

 cerely interested in his welfare. Does life exist on that planet? 

 Almost certainly there is vegetable life. We have no reason to 

 doubt it. Certain areas of the planet change in color as the climatic 

 seasons come and go, very much as we should expect if these colors 

 were controlled by the natural stages of vegetable life. However, in 

 precaution, I should guard against the drawing of the conclusion 

 that vegetable life on Mars has actually been proved to exist. I can 

 merely say that we see no reason to doubt its existence. Is there 

 animal life on Mars? There probably is, but we have no positive 

 evidence that such is the case. If the physical conditions on the 

 planet as to water, air and soil are such that vegetable life may ex- 

 ist, the chances are strongly in favor of animal life also. However, I 

 think we must leave unanswered for the present the question whether 

 such animal life is highly intelligent. The forests of the St. Law- 

 rence Valley and the prairies of the Mississippi Valley put on their 

 green coats in the spring and change them to brown coats in the 

 fall, perhaps even better before the coming of man than after his 

 destructive influence descended upon them. If you had the means 

 to ascend several thousand miles above your present position, and 

 could dwell there throughout the year, you would witness the forma- 

 tion of a polar snow cap upon the earth early in the autumn. The 

 southern edge of this cap would extend farther and farther to the 

 south up to the time of midwinter. Its edge would extend well 

 down toward the southern limits of the United States, to the Hima- 

 layas in Asia, and so on. With the coming of spring the north polar 

 cap would decrease in size and probably disappear, save as to snows 

 on the higher mountains and the possible ice and snows of the im- 

 mediate polar region. An observer similarly situated above South 

 America would witness similar phenomena as to the south polar 

 regions ; and these are indeed the phenomena observed on the planet 

 Mars. The white polar caps on Mars wax and wane with the com- 

 ing and going of the winter as they do upon the earth. Super- 

 ficially, the Martian conditions seem not very different from the 



