158 FARM ARITHMETIC. 



542. A 1,600-pound horse, working five hours each 

 day, walks at the rate of four miles an hour. What pull 

 may be expected ? 



543. An 800-pound horse working 10 hours each day 

 walks at the rate of one mile an hour. What pull may be 

 expected ? 



Draft of Farm Implements. 



Draft is the amount of force required to move a thing. 

 The subject of draft should be given the fullest con- 

 sideration in the purchase and use of farm tools and 

 implements. Draft is always at the expense of energy, 

 either motor, horse, or human, and should in general be 

 reduced to the minimum. 



This may be accomplished only by using implements 

 of the best design and construction, properly cared for, 

 sharpened, lubricated, and adjusted. An immense amount 

 of labor may be saved and much time gained in this way. 



Draft of Plows. 



The draft of a plow is the force required to pull it. 

 This force varies with the character and condition of the 

 soil and the type and condition of the plow. Many tests 

 have been made with different plows in different soils, 

 and under different conditions. The following problems 

 are constructed from some of these tests : 



544. What is the draft per square inch of a plow 

 throwing a furrow 9 inches wide and 5 inches deep of 

 blue clay, the total draft of which is 661 pounds? 



Process: 



9X5 = 45 Number of square inches in cross-section of 



furrow. 



661 -:- iS =^ 14.7 Draft per square inch. 



545. What is the draft per square inch for a plow 



