106 EUROPEAN AGRICULTURE. 



quence of the contraction of a greater bulk of earth than when 

 such soil is drained to a less depth.&quot; * 



The fact to which this very able writer refers has its diffi 

 culties, as I have before remarked ; but it is to be considered 

 that, as a larger surface is drained by a deep than by a shal 

 lower drain, the streams through the pores or the fissures of the 

 earth, which empty into it, are, of course, larger, and so acquire 

 an increased momentum in their progress. If the descent of the 

 water in the soil was altogether perpendicular, the drain nearer 

 the surface would, of course, be reached first ; but in a drain 

 much more water must come diagonally or obliquely, than per 

 pendicularly. The more land to be drained, the farther the 

 water must flow ; the farther the water has to flow, the greater 

 the volume of stream which is collected ; the larger the stream, 

 the more its momentum and velocity will be increased. This 

 supposes, however, that the passages are already opened and 

 formed. In the case of the artificial filter referred to, the water, 

 descending perpendicularly, would of course reach the bottom 

 later than it would reach any higher portion ; but, supposing the 

 filter to have been so long made that the liquid poured upon it 

 had formed various passages, it seems to me not improbable that 

 the mass of water poured upon it would reach a central point at 

 the bottom where it was to make its exit, or a basin in which it 

 was to be collected, as soon as any small quantity would be col 

 lected, at a point somewhat higher up ; and that the larger the 

 size of the filter in this case, the more surface it covered, from 

 the increased quantity, and the increased rapidity of flow given 

 to the streams flowing to this point, the sooner it would become 

 full, and even sooner than a point higher up, which would, of 

 course, affect a proportionately toss mass of surface to be drained. 



4. SIZE OF PIPES. There has been so much conversation 

 and discussion on the size of pipes, and the efficiency or capacity 

 of small pipes of only one inch bore, in effecting the drainage of 

 land, that I know I shall agreeably tax the attention of my 

 reader by quoting further from Mr. Parkes s excellent essay on 

 this subject. 



&quot; It was on the 9th of November that I inspected the drainage 



* Journal of Royal Agricultural Society, vol. v. part 1, p. 150. 



