90 IN STARRY REALMS. 



is even a thousandth part so copious as the atmosphere 

 surrounding the earth. Seeing then that air and water 

 may, for all practical purposes, be said to be absent from 

 our satellite, it becomes at once plain that those forms in 

 which life is manifested here must be absent from our 

 neighbour. Strange indeed to us would seem the con- 

 ditions of a globe without air and without water. Let us 

 try for a moment to realise what we should find such a 

 a world to be like if we could procure the means of getting 

 there, and if we were able to dispense for once with such a 

 primal necessity as air to breathe. The surface of the 

 moon would appear to be an utter desert, at least in so far 

 as the absence of organic life is concerned ; we should see 

 around in every direction huge craters, the remains of 

 ancient volcanoes that are now never in eruption, but 

 which in the days of their activity sculptured the moon 

 into the form in which we now see it. Some of these vast 

 craters (Fig. 7) would be many miles in diameter, the 

 larger of them, in fact, upwards of a hundred miles across. 

 They would be generally surrounded by a range of lofty 

 cliffs, a mile or more in height, though on account of their 

 large size relatively to the comparatively small globe of 

 the moon, these bounding cliffs or " ramparts " as they 

 are generally called, would be often below the horizon 

 of the observer who was standing in the middle of the 

 crater. Then, too, we should occasionally see great ranges 

 of lofty mountains comparable with our Alps in altitude ; 

 they would, however, like all other lunar features, 

 possess a ruggedness and a sharpness transcending any- 

 thing to be found in the wildest regions on our globe. 

 All over this earth there are agents in operation 



