PORTION OP THE COSMOS. THE PLANETS. 359 



the inequalities of the surface of our satellite. Plutarch, 

 in his small but very remarkable treatise on " the Pace in the 

 Moon," says expressly, that in the spots which we see we 

 may surmise the existence partly of deep clefts and valleys, 

 and partly of mountain summits " which cast long shadows 

 like Mount Athos, whose shadow reaches to Lemnos" ( 58 ). 

 The spots cover about two-fifths of the whole disk. Under 

 favourable circumstances of the Moon's position and the 

 state of the atmosphere, it is quite possible to distinguish 

 with the naked eye the ridges of the Apennines, the dark 

 wall-surrounded plain of Grimaldi, the detached Mare 

 Crisium, and Tycho, with the mountain-ridges and craters 

 crowded around it ( 581 ). It has been said, not without 

 probability, that it was in particular the aspect of the 

 Apennine chain which occasioned the Greeks tc regard 

 the spots in the Moon as mountains, and, as has just been 

 remarked, to refer in connection therewith to the shadow of 

 Mount Athos, which, at the solstice, reached to the Brazen 

 Cow in Lemnos. Another very fanciful opinion respecting 

 the spots on the Moon was that of Agesianax, contested by 

 Plutarch, according to which the Moon's disk was supposed 

 to reflect back to us catoptrically, as in a mirror, the forms 

 and outlines of our continents and of the " outer (Atlantic) 

 Sea." An opinion quite similar to this seems to have con- 

 tinued as a popular belief in Western Asia to the present 

 day ( 582 ). 



By the careful employment of large telescopes we have 

 gradually succeeded in obtaining a topographical represen- 

 tation of the Moon based on actual observation ; and, as in 

 Opposition, the whole of one side of the Earth's satellite 

 presents itself to our examination, we know more of the 



VOL. III. X 



