CONSTRUCTION 



137 



at least one foot from the edge, and so that together with 

 the grade stake, they shall stand in a straight line at right 

 angles to the ditch. 



When the stakes are in place, a leveling rod should be 

 set upon the grade stake. Then the grade bar, straight 

 edge up, should be placed against the stakes, with its 

 upper edge at the proper height as measured upon the 



FIG. 53. Nailing a grade bar in place. 



rod. By the use of a spirit level, laid upon the upper 

 edge of the bar, the bar is brought to horizontal and should 

 then be held firmly against the stakes and nailed in place. 

 (See Fig. 53.) All the- bars should be nailed upon the 

 same side of their stakes, that is, all facing toward the 

 outlet, or all facing toward the upper end of the drain. 

 The proper height of each bar above its grade stake is 

 found in column 10 of Table XVI. 



178. Checking. When the bars of any section of the 

 drain are up, their upper edges should lie in the same plane, 

 as one sights over them. If the upper edge of any bar 



