VENUS, MAES, AND OTHEE WOELDS ABBOT. 169 



ments as to light. We must test their qualifications as to tempera- 

 ture and moisture. In so doing we ought not to lose sight of the 

 influence of moisture on temperature. The water vapor and clouds 

 in the earth's atmosphere seem to be responsible for maintaining our 

 average temperature fully 50° F. above what it would be if, notwith- 

 standing their absence, the sun shone no more intensely on the earth 

 than now. Besides this, the range of temperature between day and 

 night, shade and sunlight, would be enormously increased if the 

 moist atmospheric blanket were removed, as all who live in deserts 

 know. 



Eeferring to the table given above, we see that, considering the 

 distances and reflecting powers of the planets, the sunlight available 

 on Mercury, Venus, and Mars is, respectively, of 12, 1.1, and 0.6 

 times the intensity of that which is available to us upon the earth. 

 As shown by the reflecting power, Mercury, like the moon, is an 

 airless, waterless waste, and being, besides, baked by a twelvefold 

 torrid heat, there can be no thought of life upon Mercury. 



Many popular writers have claimed great things for Mars as the 

 abode of life. I can not accept this view. Director Campbell, of 

 Lick Observatory, in two widely different and extremely beautiful 

 and thorough researches, satisfied astronomers that the water vapor 

 in the Martian atmosphere is less than one-fifth of the trifling quan- 

 tity which prevails over Mount Hamilton in the coldest clear nights 

 of winter. Thus, without the earth's moist atmospheric blanket, and 

 with only 0.6 the solar heat, the average Martian temperature should 

 be 60° below zero Fahrenheit. Telescopic observations reveal no 

 clouds on Mars. Its most talked-of features are dimly visible mark- 

 ings called fancifully by some " canals," but by observers like Bar- 

 nard, Hale, and others, studying under ideal conditions, regarded 

 merely as irregularities in the planet's contour and soil composition, 

 which at the immense distance are on the limit of telescopic vision 

 and take on one shape or another according to the observer's inter- 

 pretation. 



In the Publications of the Astronomical Society of the Pacific, 

 April, 1918, Doctor Campbell has confronted in parallel columns the 

 descriptions, sketches, and conclusions of the two most prominent ob- 

 servers of Martian "canals." There is apparent such widely con- 

 tradictory testimony as would be expected of two persons who should 

 try to describe the landscape of the moon without ever having used 

 a telescope. In view of the immense distance, and the equal inad- 

 equacy of the telescope for Mars and the naked eye for the moon, it 

 is probable that both of these Martian accounts are as remote as 

 theirs would be from the truth. All observers, of course, are agreed 

 as to the existence of markings and shadings of color on Mars, but to 



