THE CONQUEST OF NATURE 



in construction and of comparatively small cost, a large 

 amount of power is developed with great economy under 

 the great heads that are available. With the tremen- 

 dous water pressure developed by heads of 1,000 feet 

 and upward, which in many cases are used for this 

 purpose, wheels of small diameter develop an extraor- 

 dinary amount of power. To the original type of 

 impact wheel which first led the field have been added 

 several styles embodying practically the same principle. 

 Considerable study has been given to the designing 

 of buckets with a view to securing free discharge and 

 the avoidance of any disturbing eddies, and important 

 improvements have resulted from the thorough inves- 

 tigation of the action of the water during, and subse- 

 quent to, its impact on the buckets. The impact wheel 

 has been adapted to a wide range of service with great 

 variation as to the conditions under which it operates, 

 wheels having been made in California from 30 inches 

 to 30 feet in diameter, and to work under heads ranging 

 from 35 to 2,100 feet, and at speeds ranging from 65 

 to 1,100 revolutions per minute. A number of wheels 

 of this type have been built with capacities of not less 

 than 1,000 horse-power each." 



HYDRAULIC POWER 



A few words should be said about the familiar method 

 of transmitting power with the aid of water, as illustrated 

 by the hydrostatic press. This does not indeed utilize 

 the energy of the water itself, but it enables the worker 

 to transmit energy supplied from without, and to gain 



[74] 



