THE CULINARY GARDEN. 



57 



springs, and other circumstances for which no direct rules can 

 be laid down. We, however, may go so far as to say, that 

 deep clayey soils seldom require deep draining ; their natural 

 closeness of texture preventing the process of filtration from 

 going on ; and if rendering the surface dry, be the object in 

 view, the drains cannot well be made too shallow, provided 

 that they do not impede the necessary operations of digging and 

 trenching: for such soils, three feet may be esteemed an 

 average depth for the collecting drains, but the principal ones 

 should always be regulated in depth by the level necessary for 

 carrying off the water. 



Where the soil is of a mossy nature, the effects will be more 

 complete if the stratum be completely cut through, as the water 

 will be found in such cases to flow in greater quantities between 

 that, and the stratum immediately beneath it. Gravelly soils 

 are of all others most effectually drained, even should they be 

 charged with a greater quantity of water ; for as it is of all soils 

 the most porous, the water consequently finds a more ready 

 passage through them. As draining is attended with a great 

 expense when carried to any considerable extent, the least 

 quantity of solid matter to be removed becomes important; 

 hence it follows, that the narrower that they can be cut, the 

 less expense will attend the operation, and a less quantity of 

 draining materials will be required to fill them. As a general 

 rule, from which there are few exceptions, they should not be 

 cut broader, than merely sufficient to admit of the operators 

 getting to a sufficient depth; and in most cases, where no 

 obstacle, such as rock occurs, for drains of four feet in depth, 

 two feet in width will be amply sufficient, but for drains (jf 

 greater depth, the breadth must be increased accordingly. 



Deep drains should always be filled up and finished as the 

 operation of excavation goes on, for if they be left open long 

 they not unfrequently fall in, and often render the labor 

 and expense doubly great. When drains are made up to 

 their proper height with stones, or any of the substitutes re- 

 commended, a small quantity of heath, straw, or shavings, 

 should be put over the stones to prevent the finer particles of 

 soil filling: up the crevices between them, and where none of 



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