VALUE OFSUBSOIL DRAINAGE. 319 



one or other of the following circumstances : ist, The labourer, 

 penetrating the entire stratum of arable earth (Fig. 69, a), will 

 strike down to the subsoil (Fig. 69, b) ; or, 2d, he will not tra- 

 verse the entire stratum (Fig. 69, c) ; or, 3d, after having tra- 

 versed the entire depth of the humus, he will reach a portion of 

 the subsoil (Fig. 69, d) \ or, 4th, after having gone through both 

 humus and subsoil, he will discover another layer of arable earth, 

 which may be either pure humus, in a thick inclined stratum 

 (Fig. 69, e), or humus mixed with the debris of the subsoil. 



As for the subsoil, it may, by its composition, completely 

 modify, stimulate, or delay the action of the vegetable mould, 

 however rich this may be in assimilating principles. Thus, 

 where the subsoil is argillaceous, the pluvial waters are 

 arrested by it as by a bed of impervious cement, and render 

 the ground too damp and cold to yield abundant harvests. 

 In such a case subsoil-drainage is the best remedy. But if 

 the earth be porous, the moisture gradually percolates through 

 its various layers, fertilising and warming, communicating to 

 the plants the needful humidity, and assisting in the production 

 of that most glorious of all the scenes of cultivated nature 

 a corn-field thickly ripe with golden grain. In the poet's 

 " Palace of Art " no finer picture can be seen than this : 



" The reapers at their sultry toil. 



In front they bind the sheaves. Behind 

 Are realms of upland, prodigal in oil, 

 And hoary to the wind." 



Oh! a sight to thank God for, and rejoice in, is the field all 

 aglow with the splendour of the harvest ! 



