192 



Introduction to the Study of Science 



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. The water 

 FIG. 57 A - Cross SU ppl y f or Staten Island is 



section of the cut j j i i 



and cover" conduit' conducted through large 



of the New York City gtee l p i pes \^ on tne fl oor 

 water system. ... . 



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 se So n 5 f thTtunnei 

 more than five and one half millions, New conduit excavated 



\r i y-vj -i -i i- , i through solid rock. 



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, 



