USES OF WATER 



123 



dangerous disease germs are killed by the continuous 

 application of heat. To kill the germ of typhoid fever, 

 water should be boiled at least twenty minutes. It is 

 usually quite easy to take this precaution when the 

 purity of the water is in question, and by doing so manv 

 lives may be saved. 



City Water Supply. Civilization requires an abun- 

 dance of water. A water famine is more serious than a 



FIG. 108. A Steel Intake Crib about Five Miles from Shore. 



food famine. The community utilizes water for the re- 

 moval of sewage and for fire protection. The various 

 manufacturing plants use vast quantities of water, and 

 in the homes it is a constant necessity for drinking pur- 

 poses, for cooking, for the cleansing of soiled clothes and 

 dishes, and for bathing. 



The water supply of any city always furnishes a real 

 community problem. The Romans brought water from 

 the Apennine Mountains to Rome in great aqueducts. 

 The cities on the Great Lakes obtain their water supply 

 from the lakes, but it is necessary to take the water from 

 " cribs" considerable distances from the shore to avoid 

 the impurities from the sewage which is poured into the 



