Wind Power for Irrigation 319 



If reciprocating pumps are used, the strokes should be made 

 as long as possible and the number not higher than 20 to 25 

 per minute, to avoid loss of energy in pounding. Suction and 

 discharge pipes should, as a rule, be as large as the cylinder, 

 and where water is to be raised above the surface, this should 

 be done by carrying the discharge pipe up into the tower to 

 the necessary height to avoid the use of stuffing boxes. The 

 large wooden plunger rods, which displace one-half the volume 

 of the water raised with each stroke, are in the direction of 

 economy in making the pump in a measure double-acting. If 

 a screen must be used over the end of the suction pipe, it should 

 be given large capacity, and be carefully watched, to see that 

 it does not become clogged. All valves should have large 

 ports, easy action, and be tight fitting, so that every stroke, 

 whether slow or quick, shall discharge the full capacity of the 

 cylinder. 



There should be two pumps of different capacities, so arranged 

 that either may be used alone, or the two used at once, thus 

 providing three loads, to be applied when the wind is light, 

 medium or strong. This can readily be arranged by attaching 

 the lighter pump directly to the mill and the larger one to a 

 walking-beam ; or both may be attached to a walking-beam, 

 one end of which is carried by the driving rod of the mill. 



The geared windmills may readily be made to work a pump 

 of the bucket type, Fig. 74, and if the buckets can be provided 

 with valves which do not leak, a pump of large size may 

 be used, speeded back so as to be driven by the mill in the lighter 

 winds, and with increasing speed in the higher winds, without 

 reaching the limit at which the buckets fail to empty. 



But as the power of the mill increases more rapidly than 

 the velocity of the wind, what is needed is a device which 

 is capable of increasing the load more rapidly also. Attaching 

 an additional pump secures this end, but the objection to the 

 plan is that it is not automatic, and much service must be lost 

 by the mill being either too heavily or too lightly loaded until 

 an attendant can make the change. Still, this plan is worth 

 following until something better can be had. 



