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usually composed so largely of clay, or of very fine sand with or 

 without a clay admixture, that not even the closest joints that can 

 be made are thin or close enough, without special protection, to 

 prevent some silt being carried into the drain, whence it becomes 

 necessary to provide further means to prevent the entrance of such 

 particles. This is usually done by laying a strip of tarred paper, oil 

 cloth or heavy burlap (about an inch and one-half wide for small 

 tile and two inches or more for the larger sizes) over the top and 

 sides of each joint, in close contact with the outer surface of the 

 tiles. Strong, tough turf, with most of the soil shaken out, may 

 be used for the same purpose. 



In quicksand especial care must be observed to lay and keep the 

 tile in their proper grade and line, which may best be done by first 

 placing and securing in the bed of the trench, at the true and 

 established grade of the drain, a strip of board or plank about 

 two inches wider than the outside width of the tile itself. At 

 each joint of the boards a splicing piece about twenty inches long 

 should be laid aloug the under side of the abutting ends of the 

 boards, and both boards nailed thereto. Upon this continuous 

 foundation the tile are to be laid in a true line, and where further 

 security against lateral movement is required ordinary lath may 

 be placed on edge along and against each side of the tile, the 

 joints being first covered with strips of tarred paper or other 

 material, as above described. In back-filling the trench the 

 coarsest material that is available should be first used in contact 

 with the tile, the constant purpose to be kept in view being to 

 keep the quicksand out of the joints by placing around the tile 

 such material as will permit the admission of water only. 



Where gravel or coarse sand may be easily and cheaply obtained, 

 one of the best methods of laying tile in quicksand or soft clay is 

 to excavate the trench three or four inches below grade, and fill 

 up to the grade with gravel or coarse sand ; then lay the tile upon 

 the gravel bed in the usual manner, cover them with the same 

 material to a depth of three or four inches, and complete the back- 

 filling of the trench as before, with the coarser material toward the 

 bottom. The result is a tile drain laid in a material not easily dis- 

 placed by external influences, and surrounded by a continuous 

 filter which will admit water with the utmost freedom and exclude 

 silt. Where the cost of obtaining such coarse material is large, its 

 use may be confined to surrounding the jo iiits only, to a distance of 

 two or three inches ; but a more thorougli and permanent work will 

 be insured by bedding and covering the entire tile with it. 



Under-drains should be deep enough to encourage the fullest 

 development of root growth, to avoid any disturbing and dis- 



