120 THE BORDERLAND OF SCIENCE. 



But let us return to our oceans, remembering that 

 at present we have not proved that the dark greenish- 

 blue regions we have called oceans really consist of 

 water. 



It might seem hopeless to inquire whether this is 

 the case. Unless the astronomer could visit Mars and 

 sail upon the Martial seas, he could never learn so at 

 a first view one might fairly judge whether the dark 

 markings he chooses to call oceans are really so or not. 



But he possesses an instrument which can answer 

 even such a question as this. The spectroscope, the 

 ally of the telescope useless without the latter, but 

 able to tell us much which the most powerful telescope 

 could never reveal has been called in to solve this 

 special problem. It cannot, indeed, directly answer 

 our question. It cannot so analyse the light from the 

 greenish markings as to tell us the nature of the mate- 

 rial which emits or reflects to us that peculiarly tinted 

 light. But the astronomer and physicist is capable of 

 reasoning as to certain effects which must necessarily 

 follow if the Planet of War have oceans and polar snow- 

 caps, and which could not possibly appear if the mark- 

 ings we call oceans were not really so, nor the white 

 spots at the Martial poles really snow-caps. Extensive 

 seas in one part of the planet, and extensive snow 

 regions in another, would imply, in a manner there 

 could be no mistaking, that the vapour of water is 

 raised in large quantities from the Martial oceans to be 

 transferred by Martial winds to polar regions, there to 

 fall in snow-showers. It is this aqueous vapour in the 



