WINDMII^LS AND PUMPS. 



387 



water-lifting arrangement is not as yet wholly com- 

 plete, Yankee ingenuity will soon make it so, as the 

 principle is all right. 



Repairs of Windmills. — At least once a year a 

 windmill pumping plant should be overhauled and put 

 in repair. First the pump should be repacked, if the 

 valves leak. The check-valve must be absolutely 



FIG. 91 — THE PNEUMATIC SYSTEM. 



water-tight. Not a particle of water must run through 

 when the valve is shut. If it does the pump-pipe will 

 become empty and the water will not start for a time, 

 nor will it start at all without priming if the check- 

 valve is above the water-level in the well. The piston- 

 valve must be renewed when worn, otherwise but part 

 of the water is raised with the stroke, and when the 

 wind is light the windmill will run without raising any 

 water; this would be dangerous, for at a certain speed 



