202 



GENERAL SCIENCE 



flows from a nozzle against spoon-like blades on the 



wheel. The efficiency of such wheels may be as high 



as 84 per cent. 



135. The Turbine Water Wheel is made of thin blades 



set at such an angle 

 that the water can 

 strike them and cause 

 the wheel to rotate. It 

 is enclosed in an iron 

 casing into which the 

 water is permitted to 

 flow for turning the 

 wheel. The water falls 

 through the penstock 



and exerts a force that causes the wheel to rotate rapidly. 

 The turbine wheel was invented in 1883 and is now 



used more than any other wheel. It gives the best 



P ELTON WHEEL 



Outer case Inner case 



PARTS OF A TURBINE 



Turbine wheel 



results if a waterfall of 10 feet or more can be secured. 

 It is used exclusively at Niagara, where the water drops 

 more than 100 feet before going through the turbine 

 wheel. Some of the turbines at Niagara develop 5,000 

 horse power. One of the most powerful turbines in 

 use is at Quebec, Canada. The water falls 135 feet, the 



