636 



PRACTICE OF AGRICULTURE. 



Part III. 



494 



in the lowest part of the ground {Jig. 494 a), may be sufficient to bring off the whole of the 



water detained in the porous soil. This effect may likewise be greatly promoted, by laying 



out and forming the ridges so as to accord with the direction of the land, and by the use 



of the plough or spade in remowng obstructions, and deepening the furrows. In such 



situations, where the drain has been formed 



in this manner, the water will flow into it 



through the porous surface materials, as f| 



well as if a number of small trenches were f | 



cut from it to each side, as is the practice 



in Essex and some other parts of the coun- | 



try ; but which is often an unnecessary | 



labor and expense. The drain made in the || 



hollow may frequently serve as a division of || 



the field (a), in which case it may be open; *^ 



but in other circumstances it may be more proper to have it covered. 



3951. Where ajield of this description has more than one hollow in its surface (fig' 495 

 fl, b), it will obviously be requisite to have more than one main drain ; but when it is nearly 

 level, or only inclines slightly to one side, a trench or drain along the lowest part, and 



495 



^ 



2M ii 



fe ll: 

 Li ^ 11 



the ridges and furrows formed accordingly, may be sufficient for effecting its drainage. 

 There may, however, be cases, as where a field is large and very flat, in which some side- 

 cuts from the principal drain may be necessary, which must be made a little into the 

 clay, and as narrow as they can be wrought, and then filled up with stones or other suit- 

 able materials. 



3952. What is called the Essex method of draining in ploughed springy lands, where 

 the surface soil is tenacious, is described by Kent, and consists in substituting small 

 under-drains {fg. 496 a) for open furrows ; or in some cases having a small under- 



496 



drain beneath (b, b) every other or every third furrow. These drains lead to side oi- 

 fence ditches (p), where they discharge themselves. 



3953. Where the clay constitutes the surface, and the porous body is underneath, the in- 

 jurious stagnant water cannot possibly get off, without the assistance of drains being 

 formed for the purpose. Soils of this nature are drained with difficulty, and require a 

 much greater number of trenches or cuts than those of any other kind, as they must be 

 marked out and disposed in such a way as to collect and convey the water every where 

 from the surface ; as it can only force itself ofi' into them from above, being prevented 

 from sinking in through the clay, as in those soils of a contrary kind. Where there 

 happens to be hollows or irregularities in the surface of the land, water may often be 

 observed to continue standing in them, at the distance of but a few feet from the drain. 

 In draining such lands, it will always be necessary, in the first place, to make a large or 

 conducting drain at the lowest part, or the end of the field, for the purpose of receiving 

 and conveying away the Water collected by the less collateral cuts which it may be neces- 

 sary to make on each side of it. Where it suits for the purpose of dividing the land, this 

 principal drain may be better to remain open than be covered, as by that means the 

 mouths or outlets of the different small drains that come into it may be conveniently ex- 

 amined, and cleared out when necessary. 



3954. The construction of the ridges iri such soils, so as they may accord with the de- 

 clivity, is a matter that must be carefully kept in view. They should in all such 

 cases have, also, that degree of elevation or roundness iu the middle, that may be suffi- 



