90 SOILS 



crooked tubes hence the term "capillary," hair- 

 like. Film water passes up, down and sidewise 

 through these tubes, but mostly upward, for there 

 is where the soil is most likely to become dry. For 

 the purpose of illustration, then, we may conceive 

 that every farm soil is permeated with very fine 

 hair-like tubes which reach deep into the subsoil; 

 that it is, we will say, something like a bundle of 

 wheat straw. The lower ends of the tubes rest 

 upon the water table which may be two, six or 

 thirty feet below the surface, according to the depth 

 at which free water is found. The upper ends of 

 the tubes open upon the surface. Water is drawn 

 up through these tubes, from the water table to the 

 surface, by a kind of suction called "capillary ac- 

 tion." Capillary action is something like the pro- 

 cess by which oil is drawn up through a wick; the 

 flame that burns the oil is like the sun that 

 evaporates the water; as oil creeps up through the 

 strands of the wick, so soil water creeps up through 

 tiny pores of the soil. Whenever the sun is hot, or 

 a drying wind hugs the ground, water is drawn up 

 through these tubes. In reality the tubes are as 

 crooked and irregular as the holes in a piece of 

 cheese, yet the principle and the results are the 

 same. 



How to Prevent the Loss of Film Water. How 

 can this great loss of water sometimes amounting 

 to over one and one-half inches of rain in a single 

 week be checked ? Obviously there is but one 

 way to do it by stopping the mouths of the tubes. 

 One need not travel far to find illustrations of how 

 this may be done. Turn over a board or stone 

 lying on the ground; the soil beneath is more 

 moist than the adjacent soil; the pores of the 

 earth have been closed, and the current of water 



