500 



STATE BOARD OF AGRICULTURE. 



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

 grade stake, and the grade bar, straight edge up, should be placed against 

 the stakes and with its upper edge at the proper height as measured 

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

 of the bar, the bar is brought to the horizontal and held firmly against 

 the stakes and nailed in place. See Fig. 23. The proper height of each 

 bar above its grade stake is found in column 10 of your table. 



When the bars of the first section of the drain are up, the upper edges 

 should lie in the same plane as you sight over them. If the upper edge 

 of any bar does not lie in this plane, you have made a mistake some- 

 where either in your computations or in your work. Find your mistake 

 and correct. 



The line need not be stretched over the bars until the work of digging 

 has been started. 



Fis. 23. Nailing a'srade]' bar in place. 



2. The work of digging shoul i begin at the outlet and should proceed 

 toward the upper end. 



(a) A line should be stretched about one inch in from the grade 

 stakes to mark the edge of the ditch, and along this line the surface 

 should be cut three inches deep, with a sharp spade. The chief object of 

 the line is to insure a straight edge for the ditch. This edge should be 

 carefully worked to. 



Usually it is not necessary except with beginners to stretch a line to 

 locate the other edge of the ditch. The spade should be used to estab- 

 lish it by cutting about three inches into the surface. 



(b) Care should be exercised not to open the ditch too wide. The 

 professional ditch digger seldom opens a three-foot ditch more than 10 

 to 11 inches wide. The wider the ditch the more dirt must be handled. 



(c) With the edges of the ditch established, the removal of the top 

 soil begins, and in this work a common spade or shovel is usually used,' 

 for one cut deep. Several rods of ditch may be opened up in this way. 



(d) The next cut is made with the ditching spade following the first 

 cut its entire length. 



