16 



and disappear, the soil working easier and with much 

 more economy. 



There is always moisture enough held in the soil 

 by capillary attraction, for all the purposes of vegeta- 

 tion, and which cannot be carried off by any number 

 of drains. 



We have found by experiment that an ordinary soil 

 will hold in suspension nearly half its bulk of water; 

 which, in a soil three feet deep, would be equal to 

 nearly six months* rain-fall. Water thus held in 

 suspension does not close the pores of the soil, but 

 still allows free passage of air, since the solid parti- 

 cles, in a friable soil, occupy much less space than 

 the pores between them. 



Where the surface soil is porous and gives a ready 

 passage to the water, while the subsoil is compact and 

 impervious, then the roots of plants are compelled to 

 seek their nourishment in the surface soil only. 



Air and warmth, as well as moisture, are indispen- 

 sable to growth, and where stagnant water stops out 

 the^air and keeps the soil cold, there can be no vege- 

 tation. It is only on the lowering of the water table 

 or surface of stagnant water to a depth of three or 

 four feet from the surface, that roots are free to ex- 

 tend as deep as they may. Roots of wheat and of clover 

 have been traced to the depth of four feet or more, 

 on drained land ; and in the streets of cities, roots of 

 shade trees sometimes extend to a depth of eight feet, 

 following the line of sewers. The action of the drains 

 is immediately to withdraw the noxious water ; and 



