THE INNER PLANETS. 93 



implication of the term." He regards the canals 

 as strips of vegetation fertilised by a small 

 canal, much too small to be seen, an idea which 

 originated with W. H. Pickering. The canals 

 are believed by Lowell to be waterways down 

 which the water from the melting polar cap is 

 conveyed to the various oases. He considers, in 

 fact, that the canals are constructed by intelli- 

 gent beings with the express purpose of fertil- 

 ising the oases, regarded by him as centres of 

 population. He remarks that water is scarce on 

 the planet, owing to its small size, and as a con- 

 sequence the inhabitants are forced to utilise every 

 drop. The canal system is the result. 



Lowell's theory has not been cordially received 

 although it is now gradually gaining popu- 

 larity, and several other hypotheses have been 

 propounded to explain the canals. Proctor, who 

 died some years before Lowell's theory was given 

 to the world, regarded them as rivers, but this 

 view may now be looked upon as abandoned. 

 It was suggested that the canals might be cracks 

 in the surface of Mars or meteors ploughing 

 tracks above it : and Professor John Martin 

 Schaeberle (born 1853) of the Lick Observatory 

 put forward the view that the canals were chains 

 of mountains running over the light and dark 

 regions. None of these theories, however, gained 



