DRAFT OF OTHER IMPLEMENTS 221 



as 700 Ibs. per ton on soft ground; hence, it is hard to make a 

 comparison of the draft of wagons with other imple- 

 ments. However, two horses can usually be depended upon to 

 draw continuously about 3500 Ibs. of gross load on ordinary 

 country roads. 



Lubrication is another important factor in the draft of all 

 wheeled implements. Sanborn reports that a wagon weighing 

 3300 Ibs. with load, took a pull of 294 Ibs. with no grease and 

 243 Ibs. where lard was used. Between these two, taking 

 lard as 100, the comparative draft with other lubricants was 

 as follows: Axle grease, 100.7; cylinder oil, 104.3; castor oil, 

 106.7; lubricating oil, 112.1; coal oil, 117.6. However, con- 

 sidering the small effect of axle friction as compared to earth 

 resistance, the above results seem exaggerated. 



The draft of wagons increases with the speed of travel. 

 In an experiment in England the same load was drawn at 

 varying speeds over the same road, which included a variety 

 of grades. Taking the draft at four miles per hour as 100, 

 the relative draft was 104 six miles, 109 at eight miles, and 

 115.8 at ten miles per hour. 



Owing to the countless factors that affect the draft of 

 implements, machines, and wagons, it is apparent that draft 

 tests, under different conditions, are of little comparative value. 

 Taken absolutely, however, they give a good line on what either 

 a horse or a tractor should be expected to accomplish. A 

 wider use of the dynamometer, in connection with the exercise 

 of abundant common-sense, would undoubtedly result in more 

 humane treatment for animals and greater service from 

 traction engines. 



