474 



Irrigation and Drainage 



LOCATION OF MAIN DRAINS AND LATERALS 



After the notes of the field leveling have been 

 obtained, and the elevations computed from them, 

 these may be transferred to a diagram of the field, as 



VI 



IV III 



II 



6 



Fig. 155. Leveling for a contour map of field to be drained. 



in Fig. 155, where they will show at a glance the 

 slope of the surface, and where the mains must be 

 placed in order to secure the greatest fall, both for 

 them and for the laterals. It will be seen that station 

 VI -6 is the highest point in the field, while 1-1 is the 



