192 



Introduction to the Study of Science 



The water 



FIG. 57 A. Cross 

 section of the "cut 

 and cover" conduit 

 of the New York City 

 water system. 



a diameter of fourteen and one half feet, and it is about thirty 

 miles in length. Six miles of steel pipe complete this part of 

 the system. 



The water is brought from the west to the east side of the 

 Hudson River by a tunnel like a huge inverted siphon that is 

 1100 feet below the surface of the river. 

 Under Manhattan and Brooklyn, the con- 

 duit, a circular tunnel with a diameter of 

 fifteen feet gradually reduced to eleven feet, 

 reaches from two hundred to seven hundred 

 fifty feet below the ground surface. It is 

 excavated through solid rock, 

 supply for Staten Island is 

 conducted through large 

 steel pipes laid on the floor 

 of the bay. 



The cost of this public enterprise for an 

 adequate and safe water supply is approxi- 

 mately $185,000,000. With a population of 

 more than five and one half millions, New 

 York City's daily consumption is estimated 

 to be at the rate of one hundred gallons for each individual. 

 The amount required will certainly become greater in the future 

 per capita and for the inevitable increase in population. 



Chicago's supply and the drainage canal. In the great plain 

 and prairie region of the United States the chief sources of 

 supply are small streams, rivers, lakes, and deep wells. Cities in 

 the vicinity of lakes get their water from them and sometimes 

 turn their sewage into them. Chicago, for example, not only 

 secured its water from Lake Michigan, but for many years 

 emptied its sewage into the lake. The intakes were a mile or 

 more from shore, which distance was supposed to be sufficient to 

 avoid the danger of contamination by sewage. But pollution 

 of the water seemed certain at times, and measures were taken 

 to remove the danger. A great sanitary canal was constructed, 



FIG. 57 B. Cross 

 section of the tunnel 

 conduit excavated 

 through solid rock. 



