7CO 



PRACTICE OF AGRICULTURE. 



Part III. 



to be drained (c), up to the 

 highest and most distant sand- 

 bank (d), in such a line of 

 direction as, if possible, to 

 pass through some of the in- 

 termediate sand-beds, and pre- 

 vent the labour and expense 

 of making longer cuts on the 

 sides, which would otherwise 

 be requisite. 



4252. JFhere the different beds of sand and clay are of less extent, and lie together with 

 greater regularity, they can be drained in a more easy manner with less cutting, and of 

 course at less expense. Below the layers or beds of sand and clay that lie, in this 

 manner, alternately together, and nearly parallel to each other, is generally a body 

 of impervious clay, which keeps uj) the water contained in the sand, which sand being 

 constantly full, the adjacent clay is tliereby rendered moist, and in wet seasons the water 

 runs or trickles over it. As in these cases, the principal under-stratum of clay is rarely 

 ixiore than four or five feet below the surface, it is advisable to cut a drain {Jig. 633. a) 



feg> M A iau^3Ri!tteLab a> y<i iii A I i * iii r _^j| i t_ 



633 



-*?: i i i i i i i i i i i i M M I ; ! i i 



i 



tSSS^^^^^ 



to .that depth through the middle of the field, if it have a descent from both sides ; but 

 if it decline all to one side, the drain must be made on that side (6), as the water will 

 more readily discharge itself into it ; and, unless the field be of great extent, and have 

 ir.ore than one depression or hollow in it, one drain may be quite sufficient for the pur- 

 pose, as by crossing the different beds that retain the water, it must take it off* from each. 

 4253. A principal difficulty in draining ground of this nature, and which renders it 

 634 impracticable by one drain, is when the direc- 



' I . -fl(iii fiiVi il'''iliMS)i!to,. tion of the alternate layers, or beds of clay and 



sand, lies across the declivity of the land {fig. 

 634. a, a), so that one drain can be of no other 

 service than that of conveying away the water 

 after it has passed over the different strata, and 

 would naturally stagnate in the lowest part of 

 the field, if there were no other passage for it. 

 Where the land lies in this way, which is fre- 

 quently the case, it will therefore be necessary, 

 besides the drain in the lowest part (6), to have 

 others cut up from it in a slanting direction 

 across the declivity (c, c), which, by crossing 

 the different veins, or narrow strata of sand 

 {d, d, d), may be capable of drawing the water 

 from each of them. 



4254. Informing the drains in these cases, it 

 is recommended that, after laying the bottom in the manner of a sough, or in the way of 

 a triangle, it be filled some way up with small stones, tough sods with the green side 

 downwards being placed upon them before the mould is filled in. But where stones 

 cannot be readily procured, faggots may be employed, the under part of the drain being 

 laid, or coupled, with stones, so as to form a channel for the conveyance of the water that 

 may sink through the faggots, and for the purpose of rendering them more durable ; as, 

 where the water cannot get freely off', which is generally the case where there is not an 

 open passage made of some solid material, it must, by its stagnation, soon destroy the 

 faggots, and choke up the drain. 



4255. The estate of Spottiswoode in Berwickshire affords an interesting example of successful drainage of 

 mixed soil and strata. It was begun in 1815, under the direction of Mr. Stephens, an eminent draining 

 engineer, and author of a useful work on the subject {The Practical Irrigator, Sgc, Edin. 8vo. 1829) ; 

 and eighteen miles and a half of drains, some parts of which were thirteen feet deep, but the medium depth 

 of which was from five to seven feet, had, in 1820, rendered between five and six hundred acres of land 

 most valuable, which had been before of little value. 



4256. The grounds to be drained at Spottiswoode " consisted of a soil of various depth, under which 

 commonly lay a stratum of clay from two to three feet deep, then a thin bed of sandy or gravelly substance, 

 of a foot deep, or more, containing water ; after that another bed of clay, of two or more feet deep; and 

 lastly, a bed of sand, gravel, or slaty rock, containing the larger quantity of water. Upon reaching the 



