WINDMII,I.S AND PUMPS. 389 



five cents if produced by steam. A centrifugal pump, 

 driven by a gasoline engine, would accomplish the 

 same result at an expenditure not to exceed eight or 

 nine cents. This engine needs no attention. It uses 

 but one gallon of gasoline for each horse-power in a 

 day of ten hours. Wind engine power costs so little 

 that the total annual expense of operation is merely 

 nominal. A good windmill plant with a reservoir 

 large enough to irrigate ten or fifteen acres need not 

 cost to exceed three hundred dollars originally, and 

 such an installation would last for years. 



Capacity of Pumps. — The quantity of water a 

 windmill will lift into a reservoir during an average of 

 eight hours' run a day depends entirely on conditions. 

 If a mill of a given capacity has to lift the water from 

 a considerable depth, it cannot raise as much as if the 

 water is lifted only a few feet. For this reason, in the 

 latter case a larger sized pump may be operated by the 

 same force exerted on a smaller size, when the water 

 is taken from a considerable depth. 



Theoretically, one horse-power will raise a five- 

 inch column of water one hundred feet, a six-inch 

 column seventy feet, and an eight-inch column forty 

 feet; additional horse-power will elevate the water in 

 dire(ft proportion. A ten-foot mill will develop one-half 

 of one horse-power; a twelve-foot mill three-fourths 

 horse-power; a fourteen-foot mill one horse-power, and 

 each additional two feet in diameter of wheel develops 

 practically one additional horse-power up to a thirty- 

 foot mill, which devdops eight horse-power. The 

 cost of the mill ranges from forty dollars for the 

 smallest size, up to four hundred dollars for the largest. 



