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and in like manner, if the cut at the next peg on the same line is 

 3.8 feet, the batter board must be set 2.2 feet above it. Thus the 

 lines and grades of the entire system are established and fixed 

 safe from disturbance during the execution of the work. 



In digging the trenches, begin at the outlet or lower end of the 

 main drain and work up grade, thus giving the water encountered 

 in the work a chance to run off without pumping. It is usually 

 better also to lay the tile in the same order, especially if the 

 quantity of water is large and the trenches liable to cave. Throw 

 the surface soil upon one side of the trench and the undersoil upon 

 the other ; and in refilling restore the different materials to their 

 proper places, observing that the filling immediately around the 

 tile should be of the coarser materials best adapted to exclude silt. 



Make the trench no wider than is necessary for the convenience 

 of the workmen, say from twenty to twenty-four inches at the top 

 and from five inches upward at the bottom, according to the size 

 of the tile. Excavate to the proper grade, and dress the bottom 

 of the trench accurately by using a levelling rod or pole having a 

 target or conspicuous mark thereon at the same distance from the 

 bottom of the rod as that at which the batter boards are placed 

 above the grade line. Test the depth of the trench frequently as 

 the work progresses, by having one man hold the rod vertically in 

 it while another sights over the top of the two batters nearest 

 thereto, to determine whether the target or mark thereon is in the 

 same line with the batters. Where the target stands above the 

 line of the batters, the trench must be deepened ; while if it stands 

 below the line the trench is too deep, and must be refilled with 

 material firmly packed until the target is in the same grade with 

 the batters, with the rod standing on the bottom of the trench. 

 Constant care and watchfulness should be exercised to avoid 

 digging below the proper grade, as a natural bed that has not 

 been disturbed furnishes a better and more secure foundation 

 upon which to lay the tile. 



Of the various forms of tile in the market, that known as 

 " Ohio " or " Ohio land " tile is among the best. The bore is cir- 

 cular in cross-section, while the outside is polygonal (either hex- 

 agonal or octagonal). They have the advantage, therefore, of six 

 or more sides or beds upon which they can be laid. All drain tile, 

 however carefully made, are liable to be warped or curved in dry- 

 ing and burning, whereby with but one bed upon which to lay them 

 many of the joints are certain to gape open upon one side or 

 another, and thus admit silt more readily. A tile, however, 

 which can be laid upon any one of six or eight different sides can 

 be turned and tried upon all of them until a close joint is secured. 



