LEVELLING AND TOPOGRAPHY. 6l 



With Boundary Line as a Base. 



Having the boundary lines of the tract, go to the 

 supposed lowest point and establish a bench from which 

 to level. Run a line of levels on or near the boundary 

 of the tract, taking elevations of the highest and lowest 

 points, important ditches, ponds, etc. It will be best 

 to measure the distances, setting hubs at every 500 or 

 600 feet and note all points at which levels are taken 

 by the distance they are from the initial point. All 

 elevations should be referred to the initial bench, which 

 for convenience maybe recorded as 100. From any 

 station on this boundary, base lines can be run to the 

 interior and any desired point can be located and its 

 elevation taken, or interior cross lines can be run from 

 which the topography can be made up. During this 

 operation the engineer should keep his eyes open to 

 every peculiarity of the land over which he passes. He 

 should keep running notes in his mind and make en- 

 tries in his book of observations that may be of use to 

 him in making up his topography. 



For a survey of this kind, and in fact for any method 

 used in topographical surveys, the rodman should be 

 efficient and expeditious, thus leaving the man at the 

 instrument free to give his entire attention to his proper 

 work without being harassed by a blundering rodman. 

 Care should be taken to use every possible check on 

 the levels so that the engineer may be confident in the 

 end that they are correct* 



