EFFICIENCY OF THE HORSE 33 



increased or decreased in inverse proportion to the rate of 

 travel. The maximum draft of a horse at any time is about 

 one half his weight, and can be exerted only for a short time 

 without injury; however, there are numerous instances to show 

 that for an instant a horse may actually exert a momentary 

 pull more than equal to his weight. 



The proprietor of a very systematically managed ranch of 

 25,000 acres, in Kansas, with records covering the work of 

 large numbers of mules for thirteen years, puts the net furrow 

 travel of a plow team, spending nine hours per day in the field, 

 at from 1.5 to 1.75 miles per hour, depending upon the severity 

 of the work. In other words, the plow will actually turn a 

 furrow 1.5 to 1.75 miles long in an hour, after deducting for 

 all stops, turns, etc. Assuming Trautwine and King to be 

 correct as to the possible increase in draft during a shorter day, 

 a 1000-pound mule on this ranch should be able to overcome a 

 continuous resistance of 1000 -s- 10 X 10 -5- 9 X 2.5 -s- 1.75 = 159 

 pounds. This accords closely with what may be concluded 

 from a knowledge of the draft of plows. We may, therefore, 

 assume Sanborn to be correct in his statement that 150 pounds 

 may be regarded as the pulling power of the average plow horse. 



According to the investigations in Minnesota, the farm 

 horse works from five to six and one hah 6 hours per day, as an 

 average for the most active season. During this short day, 

 he will be able to exert much more pull than his normal ca- 

 pacity. Investigations in the Central states by one of the 

 writers showed that the work animals on farms visited, aver- 

 aged about 1300 pounds, but more than usual use was made of 

 machinery and animal power. Placing the average farm horse 

 in the West at 1200 pounds in weight, it is probable that for 

 the short day he works at the plow, he is capable of developing 

 under pressure one horsepower, which is equal to a draft of 

 187.5 pounds at the rate of two miles per hour. 



The Bureau of Statistics, United States Department of Agri- 

 culture, has for about nine years conducted careful investiga- 



