220 SCIENCE PROGRESS 



are not widely different in size) came into existence, it is 

 clear from Darwin's Tidal Theory that the moon is a frag- 

 ment broken away from Mother Earth, whereas Mars is an 

 independent planet. 



It is very probable that the moon owes its volcanic features 

 to its terrestrial origin. Mars shows none of these rugged 

 characteristics. If the planet had ever possessed mountains, 

 these should be there still — for if we assume the green areas 

 at present containing vegetation to be the beds of departed 

 oceans, it is clear that like the moon Mars probably never 

 possessed water enough to wash the mountains away. 



Lowell has calculated that if the particles of which Mars 

 is composed had fallen together under gravity the generated 

 heat of mass would probably be less than that of molten 

 iron — a temperature too low to cause much volcanic action. 

 The case is further emphasised by the fact that if the planet 

 grew gradually, it would be radiating heat and cooling layer 

 by layer as it grew. 



Another suggestion will illustrate the quandary in which 

 those are placed who attempt to explain the obviously artificial 

 canali by other means. It has been suggested that the 

 canals might be in the nature of scars left by meteorites 

 grazing the surface. Apart from the fact that meteors would 

 require special training to produce any such effect, the 

 moon again helps, for it is open to the attack of more 

 meteorites than Mars, being nearer the sun, about which they 

 all revolve : yet no such canalisation is visible on her surface. 

 With the single exception of the valley of the Alps, no lunar" 

 feature suggests this origin — and further if the valley of the 

 Alps be due to this course, its appearance shows that the effect 

 is quite different from any Martian marking, for it is at one 

 end an ill-defined scratch and in the middle a deep furrow. 



To return to the canal builders. They have had no 

 mountains to contend with. Further, the force of gravity, 

 which limits work on earth, is less potent on Mars, being only 

 about 40 per cent, what it is on earth. The same muscular 

 effort would accomplish two and a half times as much work 

 in a day against it. But though we may feel sure of the 

 existence of intellect on Mars, we know nothing and need not 

 trouble much about its physical embodiment. It is quite evident 

 that the physical difficulties have been overcome. 



