The Supply and Uses of Water 



239 



water supply of that region. The streams that flow from the 

 high watersheds of the mountains along the entire coast, not 

 only furnish at present enormous quantities of power, but are 

 capable of supplying approximately one third of the total 

 possible water power of the United States. The mountain 

 streams which were 

 early used in hydraulic 

 mining for gold, are 

 now being harnessed to 

 produce the energy re- 

 quired for industrial 

 and domestic purposes. 

 The Pelton water 

 wheel is impelled by 

 water issuing from noz- 

 zles from a common 

 supply pipe. As the 

 speed of the wheel 

 must be regulated or 

 kept practically uni- 

 form, and a change of 

 pressure in the pipes 

 cannot be made with- 

 out endangering the 

 pipes, the nozzles are 

 made so that they can 

 be deflected from or 

 toward the buckets of 

 the wheel. The ad- 



FIG. 70. The Pelton water wheel, one of 

 those used in the Rjukan, Norway, hydro-electric 

 plant, developing about 7500 horse power. 

 Estimate its diameter. 



justment is made automatically by a governor, which corre- 

 sponds to the governor on a steam engine. 



We can only with difficulty appreciate the velocity and force 

 of water having a fall of 1000 to 2000 feet. The conduits at 

 Rjukan, Norway, are of steel one inch thick to withstand pres- 

 sure of more than 450 pounds per square inch. The actual 



