160 FARM ARITHMETIC. 



554. How many such horses as the three found in 

 problem 548 should be used with this plow when they 

 walk at the rate of 1 2-3 miles an hour and work for 10 

 hours each day ? 



Important truth. These problems illustrate the 

 value of modern and improved farm implements and 



tools. 



This experiment shows that less work is required to 

 accomplish a given result, Avith modern tools than with 

 the older tools. That is, to do a given piece of work in 

 a given time, requires less horsepower, and to do a given 

 piece of work with a given horsepower requires less time. 



Plowing Sod Land With and Without Wheel Coulter. 



The table below shows the draft of a sod plow when 

 used with and without the wheel coulter. 



With and Without the Coulter. 



555. What is the draft per square inch when the coul- 

 ter is used? 



556. What is the draft per square inch when the coul- 

 ter is not used? 



557. When a plow with the coulter is used, two 1,500- 

 pound horses walking at the rate of 2.5 miles an hour and 

 working 10 hours daily are able to do the work. When 

 the same plow is used without the coulter what weight is 



