1 25 KANSAS UNIVERSITY QUARTERLY. 



Steel windmills are rapidly replacing wooden ones, mainly on 

 account of difference in cost. Probably ten times as many steel 

 mills are being sold at the present time as wooden ones. The price 

 of steel has fallen so rapidly the last few years that now steel mills 

 of any diameter can be bought for a good deal less than wooden 

 ones of the same diameter. Steel mills differ from wooden ones in 

 two or three important particulars: first, in the gearing by which the 

 steel wheel revolves two to three times to each stroke of the pump, 

 enabling it to run in a wind of a much less velocity than 'a wooden 

 one not thus geared; second, in the slats of the steel wheel being 

 curved and larger than those of the wooden one, thus making the 

 wind pressure for a given wind area greater in the former than in the 

 latter, and third, steel wheels have a less wind area than the wooden 

 ones of the same diameter. To illustrate the latter point, the wind area 

 of a " solid " wooden wheel 12 ft. diameter is 105 sq. ft. while the 

 wind area of a steel one of that diameter which the writer measured 

 is only 75.6 sq. ft. That is, the wind area of the wooden wheel is 

 1.4 times that of the steel one. 



The windmill ordinarily used for pumping water for stock is not 

 suited to the pumping of water for irrigation. It is too light and will 

 turn out of the wind for a small wind velocity. A windmill for 

 irrigating purposes should be heavy enough, and so designed that 

 its whole wind area is available for velocities of 30 miles or less per 

 hour; its wind area should not begin to lessen for a velocity under 

 30 miles per hour. The work which a windmill will do increases as 

 the first-power of the wind area and as the third power of the wind 

 velocity, hence the importance of designing the mill so that it will 

 work at a high wind velocity. It has been shown in table II that the 

 velocity of the wind at Dodge City is 11 miles or more per hour for 

 54 per cent, of the time during the irrigating season. Probably the 

 velocity is not greater than 30 to 35 miles per hour for more than 4 per 

 cent, of the time, so that a mill properly designed will run at that 

 place 50 per cent, of the time during the irrigating season, the least 

 velocity during the time being 11 miles per hour. 



The instructors in the Civil Engineering Department of the Uni- 

 versity of Kansas, and the writer in particular as instructor in irriga- 

 tion, will be glad to give to those who may wish it any information 

 on the subject of irrigation or wind motors that they can. They will 

 be pleased to receive short descriptions of new irrigation works in 

 Kansas, or of old ones not mentioned in this paper. These reports 

 will be tabulated as far as possible and a copy sent to each con- 

 tributor. 



