24 FARM AND SCHOOL PROBLEMS. 



The areas of cross sections of tile increase in size as the 

 squares of their diameters. If their diameters are 3, 6, 7, 12, 

 their areas will.be in the ratio of 9, 36, 49, 144, etc. 



PROBLEM. 



If the opening at the end of a tile 4 inches in diameter, is 

 12.56-j-sq. in., what is the area of the opening at one end of a 10 inch 

 tile? 



Solution : 4* : 10 2 : : 12.56 + : ( ? ) 

 4 3 = 16. 

 10 Z =100. 

 100 -t- 16 = 61 

 6* X 12.56 + = 78.59. 



78.59 -f- sq. in. is the area of the opening of a 10 inch tile. 



PROBLEM. 



1. How many times greater is the capacity of a 12 in. tile for 

 carrying water, than that of a 6 in. tile? 



2. W'hat size tile will be required fo carry four times as much 

 water as a 5 inch tile? 



The greater the fall, the greater the capacity to carry water. 

 Doubling the grade increases the carrying capacity approxi- 

 mately one-third. 



PROBLEM. 



1. A 6 inch tile drain which has two inch fall per 100 ft. will drain 

 a certain piece of land ; what sized tile, in a drain with a fall of 4 in. per 

 100 ft. will !be required to remove the same amount of water in the same 

 length of time? 



It has been recommended in the Government Reports, that 

 in the dark silt loams of Illinois and Iowa, where the rainfall 

 approximates 36 inches per year, the following rule holds good 

 in actual practice : 



For A Main Ditch. 



An 8 inch tile with a fall of 2 inches to the 100 feet will 

 drain 40 acres. 



A 7 inch tile with a fall of 2 inches to the 100 feet will 

 drain 30 acres. 



