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CHAPTER V. 



THE ATMOSPHERICAL PKECIPITATIONS IN THEIR RELATION TO 

 ORGANIC NATURE. 



The constant Sources of the Eivers The Harmonies of the Ocean and the Atmo- 

 sphere Distribution of Bain and Snow over the Surface of the Globe The Voices 

 of Eivers Dew History of its Formation Clouds and Eain Snow and Ice 

 as Protectors of Vegetable and Animal Life Eavines The G-laciers The 

 Tornado. 



THOUGH the voices of the rivers change with the varying sea- 

 sons loud and menacing in spring, when their floods are 

 swollen by the melted snows, and softly whispering after a long 

 summer's drought yet, over by far the greater portion of the 

 earth they never rest in total silence, nor does the rain ever 

 cease to replenish their sources or to quench the thirst of the 

 forests on the hills and of the meadows in the plains. 



This uninterrupted flow of the rivers, this constant irrigation 

 of the fields and woods, evidently points to the agency of some 

 grand and constant law, to an admirable harmony between the 

 wide sea below and the still more ample atmospheric ocean 

 above. 



Everywhere the air absorbs humidity, but chiefly over the 

 surface of the tropical ocean, where, volatilised by the vertical 

 rays of an ardent sun, the aqueous vapours ascend in amazing 

 quantities to the skies. Thus, the equatorial seas are the prin- 

 cipal sources which feed our brooks and fill our lakes; it is 

 from them that the greater part of the rain arises which refreshes 

 the verdure of our plains, and of the snow which covers the 

 northern mountains with a white mantle of dazzling brightness. 



But how are these vapours distributed over the surface of the 

 globe ? how are they conveyed to the temperate zones, or even 

 still farther onward to the frigid poles ? 



The same grand system of the winds which forces the air to 

 perpetual migrations carries also the evaporation of the ocean 

 to distant lands. I have already mentioned in a former chapter 



