CHAPTER III 

 THE DISTRIBUTION OF WATER 



The distribution of water is evidently very important. 

 We must find out about it. What is it that keeps it mov- 

 ing all over the surface of the earth? Does it move of 

 itself, or does something else move it? 



There are four things that explain the distribution of 

 water. These four things are evaporation, condensation, air 

 movements, and gravity. Evaporation explains how water 

 gets up into the air. Condensation explains how clouds 

 are formed. Air movements explain why the clouds move 

 about in the sky. Gravity explains why the rain falls to 

 the earth, and why the water goes down to the roots of 

 plants, and why the streams flow to the seas. Here are 

 four things that are at work all the time. Night and day 

 they keep the water moving. Up it goes in invisible mist 

 that changes to visible clouds. Over sea and land the 

 clouds are always moving, and somewhere the water is al- 

 ways falling back to earth again as rain. Always the water 

 that falls as rain is going into the soil and into the streams. 

 In the soil some of it enters the roots of plants, and then 

 it passes out from their leaves into the air again. Without 

 this movement of water through their bodies, the plants 

 would soon wither and die. Water lets them live and 

 grow. 



Evaporation. If you have a bird-bath in your yard, 

 you know that it is hard to keep it filled. The water evap- 



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