DRAFT OF PLOWS 215 



Several other points might be noted, including a saving of 

 7.5 per cent, by lengthening the hitch with a 13-foot chain; 

 the increase in draft noted in a previous chapter, due to the 

 downward and landward suction of the plow point; and the 

 slight increase in draft of wheeled plows on grades, but the 

 factors already discussed are the most important. 



A better understanding of the draft of plows would un- 

 doubtedly lead to greater profit and more humane treatment 

 of animals. In old land the average draft per square inch of 

 cross section probably ranges from five to seven pounds. 

 For a furrow 6 x 12 inches, the total draft would be from 

 350 to 450 pounds, while the average durable working draft 

 of a horse is found to be from one tenth to one eighth his 

 weight. Three 1200-pound horses on such a furrow would 

 probably strike the average farmer as a waste of horseflesh, 

 but the result of too little power is to be seen in the wornout 

 condition of the work stock at the end of the plowing season. 

 A wagon of 3000 pounds gross load on a sharp incline gave only 

 half the draft that a furrow 15 inches wide did on the level. 

 An all-day pull of twice that, or three tons, uphill would be 

 regarded as out of the question, yet two horses are frequently 

 called upon to do as much in plowing. In consequence, one 

 of several things must happen: Either the team must lose 

 in condition; much more food must be supplied than is ordi- 

 narily required to generate a unit of force, since above a certain 

 limit a lower percentage is assimilated ; or the quality of plowing 

 is lowered, which is the greatest loss of all. 



