Book III. 



KINDS OF DRAINS. 



639 





matters employed in filling them up, whether they be wood or straw ; but in cases where 

 bricks or stones are employed, this cannot be so much attended to; however, there is 

 seldom a necessity for a greater width than about a foot, provided the stones be coupled 

 at the bottom, or thrown in in a mixed way; nor more than sixteen inches where laid 

 in the manner of a sough or channel. But of whatever depth the materials may be, the 

 earth or mould by which they are covered up should not be less in depth than a foot ; in 

 arable lands it should be more. 



3961. The different sorts of drains in use may be classed in two divisions ; drains of 

 conveyance (fig. 499 a,b.) alone, and drains of conveyance and collection jointly {Jig. 

 499 c, d). In the former, all that is neces- 

 sary is a channel or passage for the water of 

 sufficient dimensions, which may be formed 

 by pipes of different kinds, arched or barrel 

 drains (6), and box or walled drains (a \ The 

 construction of the latter requires not only 

 an opening for conveying the water, but a 

 supercumbent or surrounding stratum( e?,/) 

 of sufficient porosity to admit and induce 

 all latent water to find its way, to the channel 

 of conveyance. The most complete drain 

 of conveyance is a large pipe of metal, 

 masonry, or brick-work ; and the most 

 complete collecting drain, one formed with a 

 channel built on the sides, and covered with 

 flat-stones, with a superstratum of round stones or splinters, diminishing to the size of 

 gravel as they rise to the surface, and there covered with the common soil. As the best 

 constructions, however, are not always practicable, the following are a 

 leading sorts adapted for different situations. 



3962. For drains of conveyance, there are the walled or box drain 

 {Jig. 499 a), the barrel drain (6 , the walled or the triangular drain 

 (c), and arched drain {fig. 500.). 



3963. Drains of collection are formed of stone, brick, gravel, 

 cinders, wood, spray, straw, turf, and earth alone. 



3964. The boxed and rubble drain {fig. 501.), has been already 

 described as a drain of conveyance and collection. The common rub- 

 ble drain is formed of rough land-stones of any sort not ex- 

 ceeding six or seven inches in diameter, thrown in the bottom, 

 with smaller ones over, and if to be had, gravel or ashes at top. 

 On this is laid a thin layer of straw or haulm of any kind, 

 and the remainder is filled up with the surface soil. 



502 

 B 



3965. The brick 

 drain is formed in 

 a great variety of 

 ways, either from 

 common bricks 

 and bats in imita- 

 tion of the boxed and rubble, or rubble 

 drain ; or by the use of- bricks made on 

 purpose, of which there are great variety 

 {fig. 502. atok.) Draining tiles to be used 

 with effect as collecting drains, should al- 

 ways be covered a foot in depth or more 

 with stones or gravel. 



few of the 



500 



^/GQ^^ 



3966. On the Marquess of Stafford's estate, " an 

 allowance of draining tiles is made, wherever the 

 exertions of the tenants seem to merit such a re- 

 ward. In order to secure the drains being properly 

 filled up with stones above the tiles, the tenant is 

 obliged to drive a sufficient quantity of stones or 

 cinders from the furnaces, and lay them on the 

 ground, previous to an order being made for the 

 delivery of the tiles. Without attending to this important circumstance, much draining would be thrown 

 away. The park at Trentham is a complete illustration of this remark. The draining of this spot was 

 conducted under the direction of Elkington. The wetness with which these lands are affected, does not 

 arise from any line of springs bursting out from the upper grounds, to which that gentleman's system of 

 deep drains could be applied ; but is occasioned almost entirely by the retentive nature of the subsoil, and 

 for its being intermixed with small basins of sand, which lie detached and unconnected with each other, 

 in the bed of clay. To cure this species of wetness, a number of small drains, well filled up, with one cut 

 into each of these beds of sand is, necessary, in order effectually to cure the evil. In pursuance of this 

 plan, a great part of the park at Trentham has been lately drained over again, by making a number of 

 small shallow drains, about fifteen feet asunder, in some instances above the old ones, takiilg particular 



