THE AUTHOR'S THEORIES OUTLINED 47 



network of lines characterizing his surface as "irriga- 

 ting canals'' completely disappears, together with all the 

 resulting speculations about the "existence of a Martian 

 race" and their "high state of development". A dif- 

 ferent interpretation of these interesting marks is there- 

 fore in order. Inasmuch as I appear to have been the 

 first to insist on the presence of extensive oceans on this 

 planet (having been led to this conclusion by my theory 

 of tidal rotation) I have ventured to invent a theory of 

 my own to show how, under Mars' natural conditions, 

 such lines might, and ought, to come into existence as a 

 plain matter of physical necessity. 



To begin with, Mars receives less than half as much 

 solar heat, area for area, as our earth ; and as we must 

 estimate this ratio, not from the ordinary zero, but from^ 

 the absolute ( 461 F.), his average climatic tempera- j 

 tare cannot but be at least 200 below our boiling point 

 of water. It is therefore necessary to conclude that 

 Mars' seas, rivers and lakes are frozen solid to a great 

 depth the year round, and to reason about his seasonal 

 changes as taking place upon this ice surface. 



Here we might hastily suppose that under the con- 

 ditions of so frigid a climate there could be no such thing 

 as water evaporation, but that water once frozen would 

 stay frozen. We must bear in mind, however, that 

 gravity on Mars is only .38 of what it is on our planet 

 and that, even conceding him as much air in proportion 

 as the earth possesses, his atmospheric pressure cannot 

 on the whole be more than one-seventh of ours. Further- 

 more, it seems reasonable to suppose that the gravity of 

 a planet, regardless of the weight of atmospheric pres- 

 sure, may affect the volatility of liquids and that, Mars' 

 gravity being little more than a third of that of the earth, n 

 water on his surface may vaporize readily, and possibly , 

 boil, at our freezing point. 



Another significant factor demanding consideration 

 here is, that the water-covered area on Mars is very much 

 greater in comparison with his land surface than in the 

 case of the earth. To many readers this statement may 



