AGRICULTURAL ENGINEERING. 493 



''The powers used to drive the several grhiders were (1) a 5-horsepower liorizontal 

 Fairbanks gay engine; (2) a 22-horsepower Webster vertical gas engine; (3) a 16-foot 

 geared Aermotor windmill, and (4) a 12-foot geared and roller-bearing Aermotor 

 windniil'. . . . 



"The two engines were able to show very nearly their rated capacity by brake 

 tests made upon the countershaft from which all of the mills except No. 1 were 

 driven. An adjustable platform was provided upon which the several mills could 

 be placed so as to be driven under every way like conditions. The fuel used by 

 the engine was the city illuminating gas, costing $1.25 per 1,000 cubic feet, and 

 the amount used was measured with a meter placed next to the engines. The wind 

 velocities under which the windmill trials were made were obtained with the aid of 

 a Kobinson anemometer. ... 



"In each trial an effort was made to regulate the feed so as, if possible, to fully 

 load the power which was being used at the time. This, however, could not always 

 be done with the 5-horsepower engine, especially when the coarser grades of meal 

 were being ground. The usual i)ractice was to start the mill with grain enough in 

 the hopper to get it regulated and adjusted to the engine and, at a signal, as the last 

 of this left the hopper, a weighed quantity of grain was placed in the mill and the 

 exact time required to run it through noted, together with the amount of gas con- 

 sumed or the miles of wind passing the windmill. . . . 



"To secure a reliable basis of judgment for estimating the amount of work done in 

 each grinding trial it was necessary to know the degree of fineness of meal produced 

 as well as the amount ground in a unit of time. . . . 



"In the trials of grinding (!orn an effort was made to produce four grades of meal, 

 (1) very coarse, suitable for feeding sheep; (2) coarse; (8) medium, suitable for 

 cattle, and (4) fine, suitable for hog feeding. . . . 



"The first degree of fineness was such as would not pass a screen of 8 meshes to 

 the inch; the second that passing a screen of 8 but stopped by one of 10 meshes; 

 the third that which would pass a screen of 10 meshes but be stopped by one of 16 

 meshes to the inch, while the fourth grade was that passing the screen of 16 meshes 

 to the inch." 



With the O Aermoter g-rincler and 12-foot roller-bearing- Aermotor 

 windmill the rate of grinding- in case of corn was '"about 25 bu. per 

 hour with a wind velocity of 31.8 miles, the meal ])eing a little coarser 

 than ' medium.' Corn and oats were ground at the rate of -110.3 lbs. 

 per hour with the wind at 26.48 miles. With a wind velocity of 26. H7 

 miles oats were ground at the rate of about 5.5 bu, per hour and rye 

 at the rate of 15.35 bu. with the wind 25.35 miles. The rye was 

 ground a little tiner than ' medium"" and the oats a little coarser.'' 



From data recorded in this and in a previous bulletin (E. S. R., 10, 

 p. 695) it appears that between October 1 and May 1 — 



"There were 87 days when a man could attend the mill and grind 10 hours with a 

 wind velocity not less than 15 miles per hour, and much of the time higher than 

 this. He should therefore be able to grind more than 46 bu. per day and on the 

 average more than 100 bu. per week. The 87 grinding days, during the 7 months, 

 places the grinding days, on the average more than two per week, and if it 

 is supposed that this is twice too high it would still be possible on the average to 

 take advantage of high winds during the working hours and grind about 50 bu. of 

 corn, or 2,800 lbs. per week. Counting the man's time who tends the mill $1 per 

 day, the cost of grinding would be only about 85 cts. per cwt. 



"Some grinding of other grains than corn with the 12-foot windmill was also done, 



