84 



ENGINEERING FOR LAND DRAINAGE 



If certain points for mapping or topography are to 

 be located from some station, the following tabulated 

 form may be employed: 



OBSERVATIONS AT PRELIMINARY STATION NO 6 



Sta 



Beanngs 



Distance 

 Feet 



Remarks 



Sta No 6 to 

 A 

 C 

 D 

 E 



N 42° 30 E 

 S 70° 20' W 

 S 6o° oo' W 

 N 20° 30' W 



800 



1000 



600 



800 



Low swale 



Walnut tree 



Upper end ditch, to hor'=!e pond 



Highest pomt m west fieJd 



The same form may be used to record a continuous 

 and connected Ime like the boundary of a farm or field 



Back sights should be taken at each station to ascer- 

 tain if there are any disturbing influences which cause 

 the needle to read differently at the two ends of the 

 line. If a discrepancy in the two readings is found, 

 some point on the same line intermediate between the 

 two should be used to determine which of the bearings 

 is correct. 



The instructions thus far given are sufficient to sug- 

 gest to the beginner the method of doing simple line 

 work with the compass. With a little practice in the 

 field, without which no one can understand the subject 

 fully, a novice may soon acquire all needed proficiency. 



