Drainage in New York. 267 



of the ditch. Another method much preferred to the previous one by 

 many practical men involves the use of " batter boards " instead of grade 

 stakes. These boards are fastened to stakes on either side of the ditch 

 at a sufficient distance — usually a foot or more from the edge of the 

 bank — to insure their security until the completion of the work. These 

 boards are placed across the ditch at intervals of fifty feet or so, near 

 enough so that a cord can be stretched between without any appreciable 

 sag at the middle. The upper edg"e constitutes the grade line and the 

 grade cord connects these points and gives a reference base directly over 

 the center of the ditch which is an important advantage. 

 d. Laying and covering the tile. 



( 1 ) Laying tile. — There are two methods of placing tile in the ditch. 

 The first is by hand. When the tile have been distributed along the 

 bank within easy reach of the man in the ditch, they may be rapidly 

 placed and any shifts necessary to make a tight fit may be cjuickly made. 

 The ends of the tile are frecjuently not square and it becomes necessary 

 to turn the tile about to get a tight fit. This may be quickly secured 

 and the tile firmly placed and if necessary, it may be wedged with earth 

 to hold it in place during the filling of the ditch. The second method 

 is the use of the tile hook shown at No. 6 in Fig. 205. It is most con- 

 venient in a very deep ditch, but is not so accurate and rapid as the 

 hand method where the former may be used. The open end of the tile 

 should always be closed by a stone or board when it is to be left for any 

 length of time as over night. 



(2) Protecting joints. — ■ In the early days of the use of tile, it was 

 customary to protect the joints by means of collars or stones. This 

 served two purposes. It aided in keeping the tile in line and also pre- 

 vented, to some degree, the entrance of soil. But the use of collars has 

 generally been discarded as expensive and unnecessary. If the tile are 

 well made and carefully laid the joints will be sufficiently close to ex- 

 clude all soils except, perhaps, the very fine sand and silt types. And 

 even these will have but little tendency to enter the tile after the soil 

 has readjusted itself and become granulated. Clay soils, medium and 

 coarse sand and gravel soils and muck give very little, if any, trouble 

 by entering a well laid tile drain. The protection of the tile from the 

 entrance of silt and very fine sand may be effected bv placing over the 

 tile a thin layer of three or four inches of coarse sand, fine gravel or 

 vegetable material, such as straw, chafif, leaves or sawdust. The 

 soil may be filled in on top of this as shown in Fig. 210. This mate- 

 rial will act as a strainer to exclude the soil from the tile while facili- 

 tating the movement of water. The latter material will gradually decay 

 and the soil will slowly adjust itself as the decay progresses without 

 harm to the tile drain. 



(3) Filling ditch. — As soon as the tile have been placed, they should 

 be covered lightly with earth to hold them in position during the sub- 



