THE PLANET MARS 219 



has brought into existence upon the earth's surface which are 

 big enough to be visible to instruments of the same order as 

 ours from a distance such as that at which Mars is situated. 

 On Mars, as on our earth, presumably the principal necessity- 

 is water and it is the means employed there to bring water 

 into operation that has proved to us the existence of the 

 intelligence which wants it. 



Like friends in need the two planets may become acquainted 

 through their necessities. 



The canali are there and it must be admitted that they 

 have been made. It is therefore of interest to inquire what 

 are the difficulties which have been overcome. In like work on 

 earth, the chief difficulty is the mountainous nature of the 

 surface, which renders world-wide canalisation almost incon- 

 ceivable. 



The first thing that strikes the observer of Mars is the 

 flatness of the surface. No mountainous markings have ever 

 been seen and yet if there were any they should be visible 

 on the terminator at sunrise or sunset by the shadow they 

 would cast. A hill 2,000 feet high would be quite visibly 

 indicated in this way. We are therefore warranted in saying 

 that there are none as big as this. Irregularities have 

 indeed been noticed on the terminator but they are only 

 explicable as high clouds or in some cases effects of con- 

 trast and irradiation due to differences of colouring of the 

 surface. Incidentally the flatness of the planet's surface, 

 which so clearly makes artificial canals easy of construction, 

 renders untenable one of the many theories which have 

 attempted to explain them as natural phenomena — volcanic 

 cracks in fact akin to those which radiate from many of the 

 larger craters on the moon. 



On Mars there are no such craters and yet on the moon 

 the craters are more conspicuous than the cracks — except at the 

 time of the full — when the lighting is more favourable to 

 the one than the other. Besides all this the lunar cracks are 

 not straight and the canals of Mars are. Now there is every 

 reason to suppose that the moon and Mars are made of some- 

 what similar materials. 



If both have cracked, there is no obvious reason why one 

 should crack crookedly and the other straightly. But whatever 

 we think of the method by which these two globes (which 



