CONSTRUCTION 143 



the walls of the ditch to fall upon the tile and accomplish 

 the same results. This covering and anchoring of the 

 tile is called blinding. (See Fig. 55.) 



188. Closing the upper end of the drain. When the 

 last tile of any drain is laid, a stone, or piece of brick, or 

 pieces of broken tile, or other solid material should be 

 laid against the upper end and earth shoveled against it 

 to hold it in place. This, later, prevents the soil from 

 working into the end of the tile. 



189. Filling the ditch. The filling may proceed as 

 rapidly as the tile are laid and anchored. It may be 

 deferred a few days, or several days, depending upon 

 circumstances. Delay is likely to result in caving of 

 the walls. In the cases of mains or sub-mains, the com- 

 plete filling is delayed until the laying of the tile in the 

 laterals is started. Usually the grade bars are removed 

 before the filling begins. Sometimes the filling is done 

 by hand ; sometimes it is hastened and cheapened by 

 the use of the plow or scraper. When a plow is used, an 

 evener must be provided that is sufficiently long to allow 

 the horses to walk on opposite sides of the ditch. When 

 the plow is used, the bars and stakes must first be removed. 

 The team is driven the length of the ditch, or for a con- 

 siderable part of it at a time, and the soil is plowed back 

 into the ditch. 



Only the board scraper is convenient for filling. The 

 team works on one side of the ditch and the man and the 

 scraper on the other. A chain or rope must be used be- 

 tween the team and scraper, which must be long enough 

 so that the team shall not be backed sufficiently near the 

 ditch to result in accident. 



When the plow or scraper is used, it is usually necessary 

 for a workman with a shovel to finish the work. 



