18 SOILS AND PLANT LIFE 



As we shall soon learn, this water must be removed before 

 plants can make a healthy growth. 



Some artificial means, then, must be adopted to remove 

 this free moisture. This is accomplished by the use of the 

 tile drain. If all the tile drain which is now laid in the 

 states of Iowa and Illinois alone were placed end to end, 

 it would make a continuous line tens of thousands of miles 

 in length. 



11. How Water enters Drain Tile. — Since the water 

 escapes through these drains, the question at once arises, 

 How does it get into the tile? Does it enter at the joints 

 or through the walls of the tile? 



Fit a cork firmly into a hole in the bottom of a flower 

 pot. Fill the pot with water. Has any water escaped 

 through the walls of the pot at the end of an hour? Of a 

 day? If little or no water can escape through the walls 

 of pots, little or none can enter. Flower pots and drain 

 tile are made of the same material. This means, then, 

 does it not, that water enters at the joints of the 

 tile. 



Lines of tile are laid not closer than a rod apart as a rule, 

 and often they are two rods apart. How is all the water 

 from this area of soil to escape through one small tile? 

 Does it enter at the top, the sides, or the bottom when it 

 finds its way through the joints into the drain? 



EXERCISE 6 



Object. — To see how and where water enters the tile 

 drain. 



Procedure. — Fill a quart can with fine sand or sandy 

 loam. Punch three holes in the can with a nail : one 

 about three fourths of an inch from the bottom; the 

 second the same distance above the first and a little to the 



