Height to 



which water 



is to be lifted. 



Efficiency of aeromotors. 



Diameter of Gallons per Diameter of Gallons per 

 pump-cylinder hour when 8-foot pump-cylinder hour when 



when 8-foot 

 mill used. 



mill used. 



when 12-foot 

 mill used 



12-foot mill 

 used. 



inches 



5ft- 

 10 



'5 .. 



20 ,, 



30,, 

 40 



50 M 

 60,, 



70 

 80,, 



100 



151. Calibre of pump-cylinder. The above table gives 

 the efficiency of aeromotors when the velocity of wind 

 is of the average strength, i.e., about 16 miles an hour. 

 A mill with a wheel 8 feet in diameter is constructed to 

 have a pump-stroke of 6 inches. A mill with a 12-foot 

 wheel is constructed either with g-inch or i foot pump- 

 stroke. The two pump-cylinders with 8-inch and 6-inch 

 diameters noted with asterisks* in the above table are 

 assumed to have the long stroke (i foot) attachment. With 

 average velocity of wind an 8-foot mill undergoes about 

 40 strokes and a 12-foot mill about 30 strokes per minute. 

 With lighter winds the efficiency is less and with stronger 

 winds, more, than what is indicated in the table. For irriga- 

 tion purposes it is best to employ a cylinder of the calibre 

 indicated in the table so as to get the maximum benefit from 

 the aeromotor. But cylinders of smaller calibre than those 



