WHY WATER DOES NOT ALWAYS FLOW 



211 



During this long journey, considerable force is expended 

 against friction, and hence the flow at a distance from the 

 reservoir falls to but a fraction of its original strength. For 

 this reason, buildings situated near the main supply have a 

 much stronger flow (Fig. 152) than those on the same level 

 but remote from the supply. Artificial reservoirs are usually 

 constructed on the near outskirts of a town in order that the 



FIG. 152. The more distant the fountain, the weaker the flow. 



frictional force lost in transmission may be reduced to a 

 minimum. 



In the case of a natural reservoir, such as an elevated lake 

 or stream, the distance cannot be planned or controlled. 

 New York, for example, will secure an abundance of pure 

 water from the Catskill Mountains, but it will lose force in 

 transmission. Los Angeles is undertaking one of the greatest 

 municipal projects of the day. Huge aqueducts are being 

 built which will convey pure mountain water a distance of 

 250 miles, and in quantities sufficient to supply two million 

 people. According to calculations, the force of the water 

 will be so great that pumps will not be needed. 



197. Why Water does not always flow from a Faucet. 

 Most of us have at times been annoyed by the inability to 

 secure water on an upper story, because of the drawing off 



