DRAINAGE 



213 



machines have not had extensive use. Capstan mole 

 ditching machines without tiles are also sometimes used 

 in tough clay subsoils, in which the drain may remain 

 open for some time. 



Outlets and silt wells. Outlets need to be carefully 

 arranged, so that stock coming to the mouth of the drain 



Figure 105. Masses of maple roots taken from 3-iiich drain tiles. 



to drink cannot disturb the ends of the tiles by 

 tramping, and it is wise to place a wire screen over the 

 opening, that rabbits and other small animals may be 

 kept out of the drains. Stones laid at the outlet, or 

 masonry built at this point, are sometimes necessary. 



