304 Ground Water, Wells and Farm Drainage. 



and expanded until its fibrils collected so much silt as to 

 completely close the drain. The willow, poplar, elm, larch 

 and soft maple are among the trees most likely to make 

 trouble in this way. 



FIG. 123. Roots of European larch removed from a 6-inch tile drain, which 

 they had effectually clogged. 



380. Laying out Drains, Careful study should be given 

 to the best manner of laying out a system of drains; the aim 

 being to secure the greatest fall, the least amount of dig- 

 ging, the least outlay for tile and the most perfect drainage. 

 To secure these results drains must be laid so that no two 

 lines are taking the water from the same territory, the out- 

 lets must be as few as possible and only as large tile used 

 as are needed to do the work. 



