DRAFT ON PLOWS 207 



of dollars. Experiments go to show that very common causes 

 effect increases of from 5 to 40 per cent, each in the draft. 

 If the United States Department of Agriculture, through a 

 Bureau of Agricultural Engineering, were to ascertain and 

 induce general recognition of the principles of draft, the farmers 

 of the country could well afford to support several Depart- 

 ments of Agriculture, each with its corps of 11,000 trained 

 workers. 



The draft data given in the following paragraphs are derived 

 from numerous sources, the chief of which are the plow trials 

 conducted by the New York Agricultural Society at Utica 

 in 1867, and reported by Gould; tests in Missouri and Utah 

 two decades ago by Sanborn; and in Illinois by Ocock in 1904. 

 The earliest of these trials were the most comprehensive, but 

 since then great improvement has been made in both plows and 

 dynamometers, and tests of modern plows might not bear out 

 the conclusions drawn at that time. It is extremely unfor- 

 tunate that the draft tests have received so little attention from 

 agricultural engineers, and that no comprehensive data are 

 available as to variations in the draft of all modern implements. 



The plow runs lightest when so adjusted as to allow the sole 

 of the landside to run level from point to heel ; to cause the line 

 of draft to pass at the same time straight from the centre of 

 resistance through the attachment at the end of the beam to 

 the point where the power is applied, and to render the angle 

 of draft i.e., the angle of the line of draft with the base line 

 as small as the application of power will allow. The loca- 

 tion of the centre of resistance varies with the character of the 

 soil, the shape of the plow, and the size of the furrow. If power 

 could be applied at the centre in a horizontal line, the plow would 

 move with the least possible draft and with perfect balance. 

 Obviously, however, it must be applied at a higher point, vary- 

 ing with the power used, and this lifting force must be over- 

 come either by adjustment of the plow or by pressure on the 

 plow handles. In the same way, if power is applied to the 



