122 THE BORDERLAND OF SCIENCE. 



towards the moon, which was at the time nearer to the 

 horizon than Mars, so that the lines belonging to our 

 own atmosphere would be stronger in the moon's 

 spectrum than in that of the planet. But the groups 

 of lines referred to were not visible in the lunar 

 spectrum. It remained clear, therefore, that they 

 belonged to the atmosphere of Mars, and not to 

 our own.' 



This observation removes all reasonable doubt as to 

 the real character as well of the dark greenish-blue 

 markings as of the white polar caps. We see that 

 Mars certainly possesses seas resembling our own, and 

 as certainly that he has his arctic regions, waxing and 

 waning, as our own do, with the progress of the seasons. 

 But in fact Dr. Huggins's observation proves much 

 more than this. The aqueous vapour raised from the 

 Martial seas can find its way to the Martial poles only 

 along a certain course that is, by traversing a Martial 

 atmosphere. Mars certainly has an atmosphere, there- 

 fore, though whether the constitution of that atmo- 

 sphere exactly resembles that of our own air is not so 

 certainly known. On this point the spectroscope has 

 given no positive information, yet it allows us to draw 

 this negative inference that, inasmuch as no new 

 lines are seen in the spectrum of the planet, it would 

 seem likely that no gases other than those existing 

 in our own atmosphere are present in the atmosphere 

 of Mars. 



But we are naturally led to inquire whether the 

 phenomena which our meteorologists have to deal 



