FACTORS OF AGRICULTURAL PRODUCTION 217 



and only a part to the fact of pulling the plow. There would 

 be some fatigue, or wearing out of horse flesh, if the team were 

 walked up and down the field all day without pulling anything, 

 though the pulling of the plow will add something to the fatigue. 

 The size of the plow to be pulled by two horses must be such 

 as to so adjust the two sources of fatigue that the total fatigue 

 will be reduced to the minimum in proportion to the work done. 



Two horses drawing a plow that turns a twelve-inch furrow will 

 travel eight miles in plowing an acre (omitting the distance they 

 travel in turning at the end of the field), but with a fourteen-inch 

 plow they will travel seven and one-seventh miles. The fatigue 

 from walking will be slightly reduced ; that from pulling will be 

 slightly increased. Which should actually prove the less fa- 

 tiguing would depend partly upon the character of the soil, 

 partly upon the character of the horses. If they were of the 

 roadster type, good travelers but poor pullers, the smaller plow 

 would doubtless prove less fatiguing; but if they were heavy 

 draft horses, the larger plow would be better. The principle of 

 proportionality has to be worked out by experiment in either 

 case. This is one of the simplest possible cases. 



Suppose, now, that you have a fourteen-inch plow and are con- 

 sidering whether to use two or three horses, though you expect 

 to plow the same depth in either case. The probabilities are 

 that if you are able to plow two acres a day with two horses, you 

 will not be able to plow anything like three acres a day with 

 three horses, without greatly increasing the fatigue of both 

 horses and man. Instead of traveling 14^ miles, it would be 

 necessary to travel 21^ miles, which in itself would prove 

 rather fatiguing without any plow. The reduction of one third 

 in t he draft upon each horse would not compensate for the add- 

 ing of one half to the distance he had to travel. Moreover, it 

 would not reduce the draft by one third because of the greater 

 speed, Any one knows that it takes more than twice as much 



