126 THE BORDERLAND OF SCIENCE. 



probable condition of Mars, with respect to those 

 circumstances which we regard as associated with the 

 requirements of living creatures, let us briefly inquire 

 how far we can determine aught as to the geological 

 structure of the planet. Here the spectroscope cannot 

 help us. The telescope, and such reasoning as may 

 fairly be applied to the relations already dealt with, 

 must here be our main resource. We see, then, that 

 the land regions of the planet present a ruddy tinge. 

 Sir John Herschel has suggested, and I am not here con- 

 cerned to deny, that this is probably due to the ochreish 

 nature of the soil. The planet, in fact, is to be regarded 

 as perhaps passing through a geological era resembling 

 that through which our own earth was passing when 

 the Old Eed Sandstone constituted the main proportion 

 of her continents. But it certainly must be admitted, 

 as a remarkable circumstance, that we can trace no 

 signs of extensive forests in Mars, nor any such appear- 

 ances as we should imagine that our prairies must 

 present to telescopists in Venus or Mercury. One is 

 almost invited to adopt the bizarre notion of that 

 French astronomer who suggested that vegetation on 

 Mars is red instead of verdant that in this distant and 

 miniature world the poet may sing of spring, more 

 truly than our terrestrial poets, that 



She cometh blushing like a maid. 



As respects the absence of forests, we may perhaps find 

 a sufficient explanation in the fact that lofty trees would 

 exist under somewhat unfavourable conditions in Mars ; 

 for gravity being so much less than on our own earth, 



