10 TILE DKAIKAGE. 



large for capillary attraction to hold the water in them up to 

 or near the surface. These larger ones are filled with air, 

 and must be, or plants will die. If you plunge a sponge 

 wholly into water (submerge it) these proper air-spaces are 

 filled with water; and if a tenacious clayey soil is not tile- 

 drained, then in a very wet time it is in effect plunged in 

 water. Its needed air-spaces are filled with water. Plant- 

 roots can get no air until the surplus water is removed. A 

 soil full of water is as unfit for work as a man full of some- 

 thing stronger. A simple experiment proves this. Plant 

 peas or corn in a tight pot or pail, and keep the soil just cov- 

 ered with water. The peas or corn will not grow. 



"Capillary water" and ''hydrostatic water." It will be 

 convenient to use both of these terms frequently in this 

 book, in a technical sense. Let us therefore agree what that 

 technical sense shall be. Capillary water, as this little book 

 will use the term, is the water which is brought from below 

 in the soil and subsoil, up to or near the surface, by capillar- 

 ity or capillary attraction ; as when a tile-drained or natural- 

 ly drained soil is moist near to the surface long after rain. 

 This is the proper condition for plant-growth. 



Hydrostatic water is that which fills the large pores of a 

 sponge, for example, when it is submerged in water, and the 

 large pores in any soil just after sudden drenching rain, or 

 of an undrained clayey soil, sometimes for days or weeks 

 after heavy rains. Capillary water is a blessing and even a 

 necessity in agriculture. Hydrostatic water, or the water 

 of complete saturation, is a great damage if continued many 

 hours, and a fatal thing to crops if continued many days. 

 It is the purpose and the actual result of tile drainage to 

 remove the hydrostatic water, the damage, and leave the 

 capillary water, the blessing. In untiled clayey soils the 

 hydrostatic water sometimes stands up or nearly up to the 

 surface of the ground for several days after the rain ceases. 

 When every u cradle-hole," or surface depression, even on 

 rolling or sloping land, stands full of water, you may know 



