110 EUROPEAN AGRICULTURE. 



The rain water which falls upon land may be detained by 

 two circumstances the first by the impervious nature of the 

 upper soil, which may be an adhesive and strong clay, through 

 which the rain cannot percolate ; the second, by an impervious 

 or indurated subsoil, either of clay or of hard pan, which holds 

 fast the water when it reaches it, and consequently the upper 

 portions become saturated or flooded. In respect to the former, 

 the adhesive clay, though there have been some failures, yet 

 there are many remarkable instances, where, by a system of 

 under-draining and subsoil-ploughing, the hardest soils have 

 been opened and rendered comparatively dry and friable. When 

 a ditch or drain has been dug, the tenacity of the neighboring- 

 soil has been loosened, and the drying of the soil in the hot sun 

 of summer has, under such circumstances, caused it to crack in 

 various directions, and, these fissures being once opened, channels 

 for the trickling of water have been formed ; others have fol 

 lowed from contiguity, and these adhesive soils, by a course of 

 cultivation, have been loosened and reduced to a condition of 

 unlooked-for dryness and fineness. Where the wetness of the 

 soil has been occasioned by a hard and impervious subsoil, this 

 evil has found no other effectual remedy than in deep draining, 

 and the thorough breaking up of this hard layer by the subsoil- 

 plough. The stratum below is often found pervious to the 

 water, which makes for itself a ready exit, when it once reaches 

 it. Some persons are of opinion that, if it were possible to pre 

 vent it, it would not be desirable to draw off the water beyond a 

 depth of from four to five feet, vegetation ordinarily not extend 

 ing beyond this, thinking that, in time of drought, the upper 

 surface might be benefited by the evaporation of the water at 

 this depth, or its ascent by the process of capillary attraction. 

 It is useless to speculate in this case, as such a matter must be 

 almost wholly beyond our arrangement or control. I ought to 

 add that, where this adhesive soil is once loosened, its porosity 

 -if I may borrow a hard word is often much assisted by 

 the common earth worms, who penetrate it in various direc 

 tions, and, directed by natural instinct, aim especially at the 

 drains or places where the water is found. Thus it is that we 

 are often served by our most humble friends, and in circum 

 stances where we never think of recognizing the obligation. 



