Book III. DRAINING. 625 



BOOK III. 



OF IMPROVING THE CULTUllABLE LANDS OF AN ESTATE. 



3908. Having completed the general arrangement of an estate, the next thing is to 

 improve the condition of that part of il destined to be let out to tenants, and from which, 

 as already observed, the chief source of income is derived. The farm lands being 

 enclosed and subdivided, and the farmeries and cottages l)uilt in their proper situations, 

 in many cases no other improvements are wanted on the soil than such as are given by the 

 tenant in the ordinary course of culture. But there are also numerous cases, in which 

 improvements are required which could not be expected from an occupier having only a 

 temporary interest in his possession ; and these form the present subject of discussion. 

 Such improvements are designated by agriculturists permanent, as conferring an in- 

 creased purchasable value on the property, in opposition to improvements by a temporary 

 occupier, the benefits of which are intended to be reaped during his lease. The latter class 

 of improvements include fallows, liming, marling, manuring, improved rotations, and 

 others of greater expense, according to the length 6f lease, rent, and encouragement given 

 by the landlord ; the former, and which we are now about to discuss, include draining, 

 embanking, irrigating, bringing waste lands into cultivation, and improving the con- 

 dition of lands already in a state of culture. 



Chap. I. 



Of Draining Watery Lands, 



3909. Draining is one of those means of improvement, respecting the utility of which 

 agriculturists are unanimous in opinion. Though practised by the Romans (143.), and 

 in all probability in some cases by the religious fraternities of the dark ages, it was not 

 till after the middle of the last century that its importance began to be fully understood 

 in Britain ; and that some individuals, and chiefly Dr. Anderson and Elkington, began to 

 practise it on new principles. About the same time, the study of geology became more 

 general, and this circumstance led to the establishment of the art on scientific principles. 

 The public attention was first excited by the practice of Elkington, a farmer and self- 

 taught professor of the art of draining in Warwickshire and the adjoining counties. On 

 the practice of this artist most of the future improvements have been founded ; and they 

 have been ably embodied in the account of his practice by Johnston, from whose work 

 we shall draw the principal materials of this section, borrowing also from the writings 

 of Dr. Anderson, Marshal, Smith, Farey, and some others on the same subject. After 

 submitting some general remarks on the natural causes of wetness in lands, we shall 

 consider in succession the drainage of boggy lands, hilly lands, mixed soils, retentive 

 soils, and mines and quarries ; and then tlie kinds of drains, and draining materials. 



Sect. I. Of the Natural Causes of Wetness in Lands, and the general Theory of Draining, 



3910. The successful practice of draining in a great measure depends on a proper 

 knowledge of the structure of the earth's upper crust ; that is, of the various strata of which 

 it is composed, as well as of their relative degrees of porosity, or capability of admitting or 

 rejecting the passage of water through them, and likewise the modes in which water is 

 formed, and conducted from the high or hilly situations to the low or level grounds. In 

 whatever way the hills or elevations that present themselves on the surface of the globe 

 were originally formed, it has been clearly shown, by sinking large pits, and digging 

 into them, that they are mostly composed of materials lying in a stratified order, and in 

 oblique or slanting directions downwards. Some of these strata, from their nature and 

 properties, are capable of admitting water to percolate or pass through them ; while others 

 do not allow it any passage, but force it to run or filtrate along their surfaces without 

 penetrating them in any degree, and in that way to conduct it to the more level grounds 

 below. There it becomes obstructed or dammed up by meeting with impervious materials of 

 some kind or other, by which it is readily forced up into the super-incumbent layers where 

 they happen to be open and porous, soon rendering them too wet for the purposes of 

 agriculture ; but where they are of a more tenacious and impenetrable quality, they only 

 become gradually softened by the stagnant water below them ; by which the surface of 

 the ground is, however, rendered equally moist and swampy, though somewhat more 

 slowly than in the former case; It may also be observed, that some of the strata which 

 constitute such hilly or mountainous tracts are found to be continued with much greater 



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