The solar Eclipse of April 17, 1912 409 



the southern limb of the common disc and so preserved con- 

 tinuity between the departing and the arriving crescents, or 

 if it passed round at all. All that I saw was the extinction 

 of the departing crescent, and, post saltum, the illumination 

 of the arriving crescent. 



When the moon is in conjunction and the sun is behind 

 it, the mountains cut by a tangential surface cannot be 

 very evident, because they can only be the summits of the 

 very loftiest peaks. The valleys are wholly masked. My 

 binocular, the magnifying power of which is only twofold, 

 shows the mountains and valleys beautifully when the moon 

 is in quadrature, but during the eclipse it made the edge of 

 the lunar disc appear as a smooth and continuous line. The 

 mountains were perfectly invisible on it ; yet what we take 

 to be their images were enormous. The phenomenon is not 

 a subjective or an instrumental spectre, because it is seen by 

 everybody, with every kind of instrument and without any 

 instrument at all. It is a reality; it must therefore be due 

 to a substantial cause, and to one which can be shown to 

 be capable of producing the effect. May not this substance 

 be the often-suggested lunar atmosphere ; and, if so, what is 

 its exact specification ? J 



1 See Contents, p. xxx. 



