456 



FARMERS' INSTITUTES. 



By consulting the meteorological tables compiled at the college, I find that 

 the wind blows faster than eight miles per hour only about one-fifth of the 

 time, while it is less than eight miles per hour fully three-quarters of the 

 time. The wind is less than four miles per hour more than one-half the 

 time. 



These results of actual trial show that the power of the wind-mill is very 

 much less than claimed by the agents or even generally supposed. Thus in 

 the region of Southern Michigan the ten-foot mill cannot be counted as aver- 

 aging 1-70 of a horse power. This will be sufficient to raise about fifty-seven 

 gallons of water one foot per minute, or about two gallons twenty-eight feet 

 per minute. Two gallons per minute is nearly four barrels per hour and 

 about ninety barrels per day of twenty-four hours. In this region the wind- 

 mill will not run, for lack of wind, but little more than one-half of the time, 

 and there are few ten-foot wheels that will raise, on the average, even when 

 running, one gallon per minute, simply because the wind is too light. 



The philosophy of the windmill was investigated by Smeaton in the 17th 

 century and by Professor Eankine in our present century. Smeaton made a 

 great number of experiments on the mills then in existence, and these experi- 

 ments form the basis of most of the theories of the wind-mill. In Smeaton's 

 time the wind-mill was the principal power available for pumping or grinding 

 grain, as the steam engine had not then been perfected. The mills of his 

 time had canvass sails, and we find from his experiments that they were more 

 ■effective than our present wooden slat mills. This is, of course, reasonable. 



Smeaton found that a wind-mill thirty-one feet in diameter in a breeze of 

 nine miles per hour, would develop one-horse power of work, or would raise 

 ^about 4,000 gallons of water one foot each minute. He found the power 

 varied with the cube of the velocity of the wind and also with the square of 

 the diameter of the wheel. Small mills are not proportionately as efficient as 

 large ones, because the friction is a greater proportion of the force developed. 



I was interested in a statement made in the Kural New Yorker of June 18, 

 by Mr. Whittemore, of the actual work of a wind-mill. His statement was 

 that a 12-feet wind-mill in a breeze of 10 to 12 miles per hour, raised 150 

 gallons per hour ; the water is raised 44 feet, and pumped a distance of 550 

 feet, doing work no doubt equivalent to raising water 60 feet. The work of 

 the mill would then be two and a half gallons raised 60 feet; or the equiva- 

 lent of 150 gallons raised one foot per minute; this amount would weigh 

 about 1,250 pounds. As a horse power is 33,000 pounds lifted one foot each 

 minute, the mill would be doing work equivalent to about one twenty-sixth 

 part of a horse power. 



