XXI 

 DRAFT OF PLOWS 



THE first steps in the development of the plow were 

 those tending to make it an effective instrument. 

 The next were naturally those looking toward the 

 elimination of human labor, and finally the draft of 

 plows was studied, not so much, perhaps, from humanitarian 

 motives as from a sense of financial loss through wasted power. 

 Comparable draft tests are so hard to obtain, according to plow 

 experts, that no data should be accepted unless all conditions are 

 known, repeated tests are made, and differences in draft so great 

 as to preclude any possibility of experimental error. Nevertheless, 

 the question of draft of implements is so little regarded by the 

 average farmer that approximate truths are worth noting. 



The total draft of a plow is the product of numerous factors, 

 each of which will vary under different circumstances. Among 

 these may be considered the weight of the plow, its shape, the 

 various adjustments, the condition of the plow with respect 

 to sharpness and scouring properties, the angle of draft, the 

 character of the soil, the skill of the plowman, the presence 

 and adjustment of various attachments, the speed of travel, 

 the size of the furrow, and others of less importance. The sum 

 of these variations may easily amount to 50 per cent., and 

 often to 100 per cent. When it is considered that an unavoid- 

 able loss in power of 10 per cent, is probably a low estimate 

 under present conditions, the tax on inefficiency is seen to be 

 enormous. The annual plowing bill of the United States may 

 be estimated at approximately four hundred and fifty millions 



