WINDMILLS AND PUMPS. 375 



The Propeller Pump. — The basic principle of 

 this pump is that the water is lifted by screws, some- 

 what similar to propeller screws, termed ' ' runners, ' ' 

 each consisting of two half-circular inclined blades 

 fastened to a shaft at intervals of three to five feet, and 

 of slightly less diameter than the casing, so as to 

 revolve freely within the well-casing, with a boxing for 

 the shaft placed immediately underneath each of the 

 runners. The boxing is held in position by a set of 

 spring blades, termed " guides," set lengthwise of and 

 engaging the well-casing, and thereby held firmly in 

 position, and so arranged as to interrupt the whirling 

 motion imparted to the w^ater as it is thrown upward 

 by the spiral adlion of the runners, and to turn the 

 water back in the opposite diredlion, thereby deliver- 

 ing it into the revolving blades of the runners in a 

 diredlion opposite to that in which the runners are 

 rotating. By this method the whirling motion of the 

 water is utilized and the capacity of the pump largely 

 augmented without increase of power. With this 

 pump water may be raised from several hundred feet 

 below the surface by extending the shaft and runners 

 down the well-casing the desired depth, it being 

 necessary, however, to always have the lower runner 

 submerged in water. 



As the shaft rotates the lower runner lifts the water 

 up to the runner above it, and that one to the next, 

 and so on until the water is delivered to the surface, 

 or above the surface if desired, the distance depending 

 upon the size and pitch of the runners, the number of 

 runners, and the speed at which they are run. No 

 increase of speed is required for additional depth. 



