208 MOUNTAINS SEEN ON THE HORIZON. 



exaggerated form, in the case of distant mountains, 

 visible upon the horizon. 



We may quote as an admirable instance of this the 

 striking panorama of the great range of the Cordilleras 

 de Los Andes, viewed from the plains region of the 

 western seaboard in South America. We feel sure 

 that all those who have travelled much in this dry 

 and sun-stricken expanse will at once recognise the 

 existence of the facts we are about to relate. * The 

 barren, desolate slopes of the mighty mountain chain, 

 sharply silhouetted upon the eastern horizon, will be 

 seen uprising out of the plain with a minute distinct- 

 ness of detail which would actually lead the observer 

 to suppose that he was within an easy day's journey 

 of their base (that might be, say, fifteen or twenty 

 miles), yet in reality they are 100 or perhaps 120 or 

 more miles away. 



The traveller however continues throughout the day 

 to plod along upon his course, yet when the evening 

 has come, and brought the labours of the day to 

 a close, he will very likely see the great mountains 

 not only no nearer than they were in the morning, 

 but as if they were actually farther away than they 

 were at the beginning of the day. The explanation 

 of this phenomenon is, as we venture to believe, some- 

 .what as follows: the slanting rays of the evening sun 

 bring out into view a curtain, or transparent cloud, of 

 exceedingly fine and almost impalpable dust, which 

 everywhere and especially in all dry regions, so far as 

 our observation goes, seems to fill the lower stratum 



* As regards the peculiarities of the meteorological conditions of this 

 region, we beg to refer the reader to our chapter on Climates and 

 Temperatures, Vol. i. 



