14 UTILIZATION OF WATER POWER AT NIAGARA FALLS. 



A very interesting feature is the manner in which the enormous 

 weight of the revolving parts is supported. Consider for a mo- 

 ment a weight of 76 tons revolving at the rate of 250 revolutions 

 per minute. The weight is equal to that of 1000 persons of average 

 size and is moving at an average rate about equal to that of the 

 Empire State Express. You can readily see that it is no slight 

 task to support such a mass. Lignum-vitae, cast iron and steel have 

 been successively recommended for this purpose but in wheelpit 

 No. 1 the great majority of the revolving weight is borne by the 

 same water that drives the wheels. It is difficult to explain this 

 without the aid of a model, but some idea of the principle may be 

 gained when it is said that a hole is cut in the top of the wheel 

 case and into this hole is fitted a disc which connects the wheel to 

 the shaft. This disc is so proportioned that the water in the wheel 

 case acting upward with a pressure of 56 pounds per square inch 

 of disc balances the moving weight. 



As the pressure in the wheel case varies with the amount of 

 power developed the revolving weight cannot be exactly balanced 

 at all times, but with the Fourneyrou wheels such unbalanced 

 weight under ordinary circumstances never exceeds 3500 lbs., and 

 this is readily supported by collars placed on the shaft about 15 

 feet below the power house floor. 



For electrical generation it is of course necessary that the speed 

 of the turbines should be kept constant at all times. In order to 

 accomplish this a cylindrical gate is placed on the outside of the 

 wheels, such gate being connected by a series of levers with a gov- 

 ernor placed on the power house floor. The gate is thus raised or 

 lowered to correspond to the amount of load on the generator. 

 For example if the machine is fully loaded the gate is raised to its 

 highest position, thus uncovering the entire wheel and allowing 

 the maximum amount of water to escape. If then a customer con- 

 nected with such dynamo should suddenly throw off 2500 H. P. it 

 would be necessary that the gate should be approximately half 

 closed or one half of the power developed would be used to make 

 the wheel run away. Immediately upon the withdrawal of the 

 half load the governor automatically acts to half close the gate. 

 More than once during the operation of the plant the entire load 

 has been instantly thrown off and the governors have closed the 

 o-ates without any serious increase in speed. The strength of the 

 revolving parts is so calculated that the speed may be increased 

 60% without increasing the stress beyond the safe limit. The 

 governors on the first three units were designed by Faesch & Pic- 



