WATER 



71. The Source of Water. In the beginning, the earth 

 was stored with water just as it was with metal, rock, 

 etc. Some of the water gradually took the form of rivers, 

 lakes, streams, and wells, as now, and it is this original supply 

 of water which furnishes us all that we have to-day. We 

 quarry to obtain stone and marble for building, and we 

 fashion the earth's treasures into forms of our own, but we 

 cannot create these things. We bore into the ground and 

 drill wells in order to obtain water from hidden sources; 

 we utilize rapidly flowing streams to drive the wheels of 

 commerce, but the total amount of water remains practically 

 unchanged. 



The water which flows on the earth is constantly changing 

 its form ; the heat of the sun causes it to evaporate, or to 

 become vapor, and to mingle with the atmosphere. In time, 

 the vapor cools, condenses, and falls as snow or rain ; the 

 water which is thus returned to the earth feeds our rivers, 



lakes, springs, and 

 wells, and these in 

 turn supply water to 

 man. When water 

 falls upon a field, it 

 soaks into the ground, 

 or collects in puddles 

 ' which slowly evapo- 



fee 



rate, or it runs off 

 and drains into small 

 streams or into rivers. 

 That which soaks 

 into the ground is 



the most valuable because it remains on the earth longest 



and is the purest. 



Water which soaks into the ground moves slowly down- 



FlG. 38. How springs are formed. A, porous layer 

 B, non-porous layer ; C, spring. 



