DRAINAGE. 113 



water operated upon by the drain is that which lies at the 

 level of its own bottom, which runs off, and is replaced by 

 that which was immediately above it. And on account of 

 this operation, which we have before explained, it is 

 necessary in retentive soils, in which friction is greater 

 than in porous, to have the drains deeper, in order to 

 lower the water-table to the same extent. A column of 

 6 inches may suffice to push water from the intermediate 

 point between two drains in a porous soil, and it may 

 require a 12-inch column in a retentive. In that case the 

 drain in the retentive soil must be 6 inches deeper than 

 in the porous. Ignorance says, Drain shallower because 

 your soil is retentive. Experience and reason say, Drain 

 deeper. We may here notice, that in clay lauds the portion 

 within 1 or 2 feet of the surface is almost always more 

 retentive than that which lies below; simply, we appre- 

 hend, because its particles have been comminuted and 

 packed close by the alternate influences of wet and dry, 

 heat and cold. When dried below by drains, and above 

 by evaporation, it is certain to crack and become perme- 

 able ; and this operation may, if necessary, be assisted by 

 subsoiling or other artificial means. 



The practice of deep thorough-draining is not quite new 

 in England, for, if we remember right, Arthur Young 

 states that the best draining which he saw in his agri- 

 cultural tour was in Yorkshire, on an estate of Lord 

 Rockingham's, by parallel drains 4 feet deep running in 

 the line of steepest descent. Nothing more was heard of 

 the matter till a few successful cases in Kent and Sussex 

 were offered to the notice of agriculturists. No sooner, 

 however, was the practice advocated strongly by Mr. 

 Parkes and others, than a host of correspondents of various 

 agricultural publications furnished more instances of the 

 abandonment of deep draining on account of failure than, 

 we verily believe, they could have authenticated cases of 

 practice. Probably it is not now necessary to advert 

 further to such statements. We believe that they have 



