XIII 



THE MOON 



THE general reader would naturally suppose that 

 since we are able to form an idea regarding the 

 character of Mars' surface, which, at the best, is 

 more than 140 times as far from us as is our satellite, it 

 should be a comparatively simple matter to construe the 

 lineaments of the moon. Such, however, has not proved 

 to be the case. In round numbers the moon is only 240,000 

 miles from us, and has a diameter of 2163 miles, being a 

 fraction over half that of Mars. When viewed through a 

 telescope of about 400 diameters (which is found by ex- 

 perience to be the most satisfactory, everything con- 

 sidered) , it is possible to perceive, though as a mere 

 point, any feature upon its surface as large as an ordi- 

 nary city block. 



There are two peculiarities about the moon which 

 have puzzled astronomers beyond measure and which un- 

 til the initial appearance of this work, in 1912, had es- 

 caped their true solution. One of these is that it pre- 

 sents only one side toward us, and the other, that its 

 topography appears to be so abnormally volcanic in char- 

 acter. 



