172 BOOK OF NATURE LAID OPEN. 



must be attended with most beneficial consequences; 

 but as the sea, for its purity, is not dependent on any 

 one cause, so the atmosphere, besides these external 

 restoratives, will be found to contain, in its own bo- 

 som, a correcting principle, which developes itself 

 by its salutary operations, as we shall soon have oc- 

 casion to notice, in speaking of some of the most 

 remarkable of the phenomena of the atmosphere. 



CHAP. XV. 



PHENOMENA OF THE ATMOSPHERE; 



" Of what important use to human kind, 



To what great ends subservient is the wind? 



Where'er the aerial, active vapour flies, 



It drives the clouds, and ventilates the skies ; 



Sweeps from the earth infection's noxious train, 



And swells to wholesome rage the sluggish main!" 



The Wind. 



SOMETIMES there is a profound calm ; every wind 

 is hushed; not a zephyr breathes over the face of 

 creation, and not a breeze disturbs the glassy ex- 

 panse of the lake; but the appearance is deceitful 

 and short lived ; all on a sudden the wind is heard 

 rustling among the branches it gathers strength as 

 it proceeds, and grow r s up into the majesty of a storm. 

 Now the raging tempest spends its fury; houses are 



