LEVELLING AND TOPOGRAPHY. 



63 



angle from base line to the new points. Each one may 

 now be used as a station in planning and locating the 

 drains immediately surrounding it. The data taken in 



Fig. 12.— Topography from , Central Base Line. 



this work should be sufficient to plat the drainage sys-- 

 tern correctly, or if only preliminary levels are desired 

 the field points can be platted. As many points may 

 be located and levelled as may be necessary to plat the 



