CHAPTER VI 



MAN'S SUPPLY OF WATER. THE INSIDE OF 

 THE EARTH 



The Sources of Water-Supply. Where does the water 

 that you use in your own house come from? Probably 

 all you have to do to get it is to turn on a tap and let it 

 run. Think now where it comes from and how it gets to 

 you. 



Lakes, rivers, springs, wells, and cisterns are the sources 

 from which men get the water they need. Nearly all great 

 cities were originally located on lakes or rivers; these were 

 important for water-supply as well as for transportation. 

 But when homes had to be made in the country, away 

 from lakes and rivers, springs were looked for and wells 

 were dug. No house was built unless there was near it 

 a convenient supply of water. Wells are very ancient. 

 The Old Testament and other books of ancient history tell 

 of their important part in the life of the people. 



A well is just a hole dug in the ground with water in it. 

 A deepened spring is a sort of well. We may say that the 

 reason a well has water in it is because the hole has tapped 

 an underground spring. So there is no absolute difference 

 between a well and a spring. There is water in the ground. 

 When this water comes to the surface of its own accord, 

 we have a spring (see Fig. 1 1) ; when we dig for it, we have 

 wells. Whether we strike water or not when we dig de- 

 pends a good deal on chance, but not so much as it used to. 

 Modern science furnishes information which enables ex- 

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