RECLAIMING MUCK LAND 47 



the rod for a front-sight, which is 4.27 feet 

 in the case above. This means that B is 4.27 

 feet lower than the height of the instrument. 

 For this reason 56.32 minus 4.27, or 52.05, 

 is the elevation of B. 



Line of Levels 



Then carry the instrument ahead to a 

 point Y about 20 rods beyond B and set it 

 up once more. With the bubble centered, 

 read the rod held for a second time on B. 

 By adding this back-sight reading of 6.87 to 

 52.05, which is the elevation of B, the new 

 height of the instrument is found to be 58.92. 

 Then by pointing the level at C and reading 

 the rod there, a front-sight (5.04) is ob- 

 tained, which subtracted from 58.92, gives 

 C an elevation of 53.88. Since A has an 

 elevation of 50, it is evident that C is 3.88 

 feet higher than A. A line of levels has 

 been run from A to C. 



