DicviNAGE IX New York. 



263 



tendency for tlie roots to enter the tile. But if the tile carries water 

 from a spring which flows in dry weather, this flow of moisture will 

 keep the adjacent soil in a moist condition which will attract the roots 



and may lead to their developing into the tiles. 

 In such cases, it may be desirable to cement the 

 joints of the tile in the neighborhood of trees. 



(3) Outlets. — The outlet of a tile drain should 

 be clear and unobstructed. Figs. 203 and 204 show 

 examples of bad outlets. In the first case the 

 caving of the bank and perhaps the tramping of 

 stock displaces the tile and they become filled 

 Fig. 203.— a neglected ^^[i\-^ soil thereby becoming ineffective. In the 

 Hon as a result of second case the outlet is drowned, that is, the 



cazing of the bank, mouth of the tile is below the level of the water 

 Probably accelerated ^ . . , , „, . •. i.i 



bv tramping of stock surface in the open channel, this permits the 



accumulation of sediment in the last few lengths 

 of tile. It also renders the last few rods ineffective as drainage because 

 the water backs up in the tile until the tile is above the level 

 of the water surface. If the fall is only a few inches per hundred feet, 

 this may render useless as many hundred feet of the drain. The 

 water should have a free flow from the mouth of the tile. A. well con- 

 structed mouth of a drainage system is 

 shown on title page. It is laid up in stone to 

 prevent the caving of the ditch bank and the 

 end of the tile is screened by means of three 

 or four heavy wires or rods set in a wooden 

 frame which fits over the end of the tile. 



Its purpose is to prevent the entrance of Fig. 204.— A "drowned" outlet 



,,.,,., , 1,111 due to level of zvater being 



small animals which may enter and get lodged /,/^/;^,- than mouth of_ the 



in the tile, obstructing the flow of water. i'^lc drain. An undesirable 

 Under all conditions the last rod or two of the 



drain should be composed of hard conduit. Sewer pipe is sometimes used. 

 A plank box or an iron pipe is also used at the outlet, but the place of 

 both of these may be taken by hard burned or vitrified tile of the ordinary 

 type. However, one advantage of a long plank box or the iron pipe, where 

 the outlet is in a soft bank unsupported by stone work, is that it will be 

 less affected than the tile by the caving of the bank of the open 

 ditch. 



If the water has any fall from the mouth of the tile it should strike 

 a stone or cement bottom which is united to the tile.- Erosion is likely 

 to occur which may undermine the tile and destroy an otherwise good 

 outlet. 



