206 OUTLINES OF FORESTRY. 



land, the water, the air, the plants and animals, in 

 order that the complex organization of nature may 

 be properly maintained in operation. 



The energy which is the cause of nearly all 

 natural phenomena of the earth is received directly 

 from the sun. 



One part of the sun's heat stirs the air and 

 water in vast movements between the equator and 

 the poles, and thus effects an interchange between 

 the too great heat of the equatorial regions and 

 the too feeble heat of the polar regions. Another 

 part of the solar energy is directly expended in 

 producing one or another of the myriad forms of 

 plant or animal life. 



If the land, the water, or the air receives more 

 than its share of solar energy, a disturbance in 

 the balance of nature is effected, which produces 

 marked effects in the life of the earth. 



The total water area of the earth bears a pro- 

 portion to its total land area very nearly as 25 is to 

 9, or as 2 is to 1. 



The earth receives its greatest heat from the 

 sun at those parts of its surface where it has its 

 greatest water areas, only a comparatively small 

 part of the land being found in the equatorial re- 

 gions. There are produced, however, vast currents 



