190 



Introduction to the Study of Science 



water is brought to the city. In quantity there is more than 

 sufficient to supply the needs of two millions and more of 

 people. The water pressure in the city is so great as to render 

 unnecessary any additional force, as by pumps. This, how- 

 ever, is not unusual on the Pacific coast or in the Rocky Moun- 

 tain region where 

 the supply comes 



from great 

 tudes. 



alti- 



FIG. 55. Section of con- 

 duit of the Los Angeles water 

 supply. A steel siphon cross- 

 ing nine-mile canyon 850 feet 

 deep. It rises on the other side to within 30 feet of height on this side. Insert : 

 Diameter of steel pipe is 11 feet, its length 30 feet ; the steel is 1| inches thick. 



The New York City supply. After many years of de- 

 pendence upon the Croton watershed for its supply, New 

 York City has gone far north into the Catskill Mountains 

 for a source of supply that bids fair to satisfy its needs for 

 many generations to come. It has acquired control of the 



