102 FROM NEBULA TO NEBULA 



where he assumes vegetation to get the earliest start 

 must be perpetual, and vegetation altogether impossi- 

 ble, whether with or without water, be it warm or cold. 

 The second reason is, that the water freshly melted 

 from the snow-drifts would be veritable ice-water, and 

 would be no stimulant to plant-life in a warm, let alone 

 in so cold a climate; and, third, it is only by screwing 

 up his estimate of Mars' temperature to the last notch 

 that he can convince himself or others that life, even on 

 Mars' equator, is possible, not to speak of canals and 

 oases at its very poles ! Then there is the sensible, eco- 

 nomical reason, that the canny Martians of the tropics, 

 did they actually exist, should long ago have learned to 

 take thought for the future, and to provide in advance 

 stores of water against the opening of the season; so as 

 not to be dependent upon their esqiiimaux for their early 

 spring vegetables. 



A NEW THEORY ABOUT MAKS 



1. Analogy would lead us to expect seas on Mars. 

 And behold the shining proof of them in the polar caps 

 and their seasonal coming and going. 



2. Unlike our polar snows, which are perpetual, 

 Mars 7 snow-caps totally disappear every season save for 

 a small bonnet at the northern pole, which always stops 

 short at the same minimum size. Two agencies capable 

 of causing the mere thawing suggest themselves, namely, 

 heat and flowing* water. Internal heat is out of the 

 question, since in that case the snow could never have 

 lain in the first instance. Solar heat, if sufficiently ar- 

 dent, might explain the disappearance of the snow, but 

 not the sparing of that pertinacious bonnet, which defies 

 any explanation save that it rests on land, and, con- 

 versely, that the remainder of the cap which season ally 

 disappears rests on an ice-crust. 



