452 



Irrigation and Drainage 



between laterals is about 150 feet ; an effort was not 

 made to secure perfect drainage, but rather so nearly 

 sufficient for ordinary crops as to make the increase 

 in yield pay a fair return for the money invested. 



Fig. 141. Drainage system of 80 acres. Double lines represent mains ; single 

 lines are laterals. Numbers give length of drains and diameter of tile. 

 After C. G. Elliott. 



The double lines represent the mains and sub -mains; 

 the single lines are laterals, and the numbers of three 

 or more figures express the number of feet of each 

 size used in the line against which they stand, while 

 the single figures under these show the inside diame- 

 ter of the tiles used. 



It will be seen that the main begins with 1,000 

 feet of 7 -inch tiles, carrying the water from 80 acres 

 of flat land surrounded by comparatively level fields ; 

 next follow 1,200- feet of 6 -inch tiles, then 600 feet 

 of 5 -inch, the line closing with 157 feet of 4 -inch 

 tiles into which no laterals lead, 



