TO STUDY THE OPERATION OF TILE DRAINS 39 



sel with soil and pour on water at regular intervals, giving 

 it time to soak into the soil. The water, instead of coming 

 out at the tubes, will pass downward through the soil 

 until the solid bottom is reached, when a water-table of 

 free hquid will be formed at a level indicated by the height 

 of water in the glass stand-pipe. When the free water has 

 risen to the first opening it will pass outside the vessel, 

 thus proving that a tile drain placed as low as soil con- 

 ditions will permit removes free water before one placed 

 nearer the surface. 



Discussion: The lower tube in the drainage apparatus 

 or the lower hole in the can represents a deep tile drain, 

 while the upper tube or hole represents a shallow drain. 

 The object of the tile is to prevent the rise of the ground 

 vvater surface which interferes with the root development 

 of the plants. 



