102 ROUGH WAYS MADE SMOOTH. 



history of our earth may have have been from the moon's, 

 terrestrial regions exist where the characteristic features of 

 the moon's surface are more or less closely illustrated. 

 ^<>uthe A^enca^n , continent, for example, there are pecu- 

 liarities ' of geological formation which seem to correspond 

 .closely; with; some oi\ the features of the lunar globe, 

 presently to : be noticed ( and it seems to me not improbable 

 that geologists might find in the study of certain regions in 

 North America the means of interpreting the difference 

 of tint between higher and lower levels on the moon. If 

 so, light would probably be thrown on very difficult questions 

 relating to the remote past, not only of the moon, but of 

 our own earth. 



The lunar feature which comes next in importance to 

 the difference of tint between the so-called ' seas ' and the 

 higher lands is the existence of remarkable series of radiat- 

 ing streaks extending from certain important craters 

 centres probably of past disturbance. It is impossible to 

 contemplate the disc of the full moon, as seen with a 

 powerful telescope, without feeling that these systems of 

 rays must have resulted from the operation of forces of the 

 most stupendous nature, though as yet their true meaning is 

 hid from us. They would be marvellous phenomena, even 

 if they were not so mysterious marvellous in their 

 enormous extension, their singular brightness, and their 

 manner of traversing 'seas/ craters, and mountain-ranges 

 indifferently. But their chief marvel resides in the myste- 

 rious manner of their appearance as the moon approaches 

 her full illumination. Other lunar features are most clearly 

 recognised when the moon is not full, for then the shadows 

 which afford oar only means of estimating the height 

 of lunar irregularities are clearly seen along the border 

 between the bright and dark parts of her face, and we have 

 only to wait until this border passes over any object we 

 wish to study to obtain satisfactory evidence of its nature. 

 It is quite otherwise with the rays. The regions occupied 

 by these radiating streaks are neither raised nor depressed 



