CHAPTER XII 



LEVELING AND GRADING TILE DRAINS 



Taking Levels. After the drains have been staked, levels 

 should be taken with an instrument on the grade stake at 

 each station and recorded in the field book. This is the 

 process of leveling which has been mentioned in a previous 

 chapter. Notes for each line, be it main, submain, or lateral, 

 should be kept under an appropriate title or head, and all the 

 levels should refer to 

 a common datum. If 

 the instrument is pro- 

 vided with a compass, 

 the bearings of the 

 line should be record- 

 ed on the right hand 

 side of the note book 

 beside the level notes. 

 A good system of 

 notes is shown in the 

 specimen pages from 

 a field book found in 

 Part I. 



The Grade. The 

 amount of slope given 

 to tile drains is called 

 the grade and is stated in several ways. The more common 

 way is to give the change in elevation of the drain for 

 every hundred feet of length. It is also stated as the 

 percentage the change of elevation is of the length. Thus 



73 



Fig. 50. Taking levels in making a survey. 



