460 THE MOUNTAIN. 



surface tne appearance of excessive dampness beneath the 

 canopy of branches and leaves. 



There are really upon the mountain no special local phe- 

 nomena on this point visible or demonstrable except those di- 

 rectly dependent upon this " boundless contiguity of shades." 

 To the influence of this cause is due the growth of the vast 

 number of lichens and mosses, which are here found investing, 

 as parasites, the bodies of trees, logs, and rocks, through 

 the deeper and more protected parts of the forests, seem- 

 ing to indicate an undue amount of moisture, while, as al- 

 ready remarked, experiments demonstrate it not to be the 

 case. The dew and rain precipitations, which, falling upon 

 a cleared and open soil permanently heated by the direct 

 rays of the sun, are speedily driven off, remain, on the con- 

 trary, in these impenetrable shades, prevented from exhaling 

 by the mantle of trees and bushes, ferns and mosses, and 

 pass off by slower evaporation, but principally underneath, 

 giving origin to the numerous springs with which the moun- 

 tain abounds. 



As a direct consequence of this, the formation of large 

 bodies of low fog is unusual, and the dense masses of vapor, 

 resting for hours in the valleys aad lowlands, is of unfre- 

 quent occurrence in the mountain ranges. Occasionally a 

 silver veil of snow-white fog is seen overhanging the deeper 

 valleys, ravines, or gorges, but it is as evanescent as a wan- 

 dering cloud, and looks often, in the distance, like a sheet of 

 water or mountain lake sleeping in repose among the hills. 

 Like the mirage of the desert, these white clouds, settling in 

 the depressions of the mountain, simulate, to absolute perfec- 

 tion, bodies of water reflecting the light of the sky, and the 

 pictures are so artistically elaborated that the captivated be- 

 holder cannot disenchant himself from the beautiful illusion. 

 Preceding and following the storms, low fog often envelops 

 the spurs of the mountain ; as also the regular storm-scud, 

 occasionally, when the overhanging mass, heavy and low, 

 sinks down to the stratum of the storm, or high-fog, em- 

 braced within a half mile of the surface. 



