SPRINGS AND WELLS 



77 



table matter or sometimes a poor quality of paint used on 

 the roofs will come off in the water. All of these things 



Diagram to show the relation of springs and wells to underground water. 



cause rain water to become unfit for drinking purposes. 

 An excellent plan is to have the first water which falls run 

 off without entering the barrel or cistern, because that 

 water is almost sure to contain dust and other impurities. 

 The best type of cistern is a tank of non-porous material 

 placed in the ground. 



Springs and wells. Any boy or girl who has lived in 

 the country knows what a spring is and any one with a 

 little thought can see how a spring might arise from rain 

 water. The rain soaks into the ground until it comes to 

 a layer through which it cannot pass (impervious layer). 

 It then seeps along until it acquires pressure enough to 

 flow out. If the saturated zone rises to the surface a 

 spring may result. A glance at the accompanying diagram 

 will show how springs occur. In a gushing spring the water 

 is forced out under pressure. Water which has soaked into 

 the ground at some point far distant, often travels under- 

 ground between two layers of impervious material, follow- 

 ing along some layer of soil or rock which allows its passage, 

 and finally finds its way to the surface through some crack 

 or hole in the hard rock. Artesian wells are made when 



