DRAINAGE 



77 



a drainage system without providing the owner of the tract 

 drained with such a map. 



Fig. 52. A drainage map. 



QUESTIONS 



1. What should be recorded in the field book when taking levels 

 for a tile drain? 



2. What is meant by the "grade" or "fall," and in what three 

 ways may it be designated? 



3. What is meant by the grade line? 



4. Explain two methods of establishing the grade line. 



5. Why is a uniform grade desirable? 



6. Explain how laterals should be joined to mains or submains. 



7. What construction figures should be placed on the guide stake? 

 ' 8. Describe the construction of the final map. 



