BOOE III. 



DRAINING MIXED SOILS. 



'01 



lower of these porous strata, the water disappeared in the upper one : and hence generally the expediency of 

 not stopping at the first, but of working down till the main stratum was reached. Several instances occurred 

 where the strata lay too deep to l>e reached by a drain ; in which cases it was deemed necessary to sink 

 wells or pits at certain distances along the line of the drain, from ten to eighteen feet deep, or more, in 

 order to reach the open strata, so that the water, rising through the wells to the bottom of the drains, mi^t 

 be conveyed away without reaching the surface. It was never thought sufficient to have reached the first 

 seam containing water, unless it were at the depth of four feet or more, and evidently appeared to be that 

 containing the main body of water which occasioned the wetness of the surface." {Trans. Highl. Sov.}- 



4257. The first operation in the p)-ocess of draining " was to ascertain the depth and nature of the 

 strata in which the water was contained, and the overtiowing of which, where no outlet existed, produced, 

 as was before remarked, either springs or bursts of water, or a general oozing. Along the line of these 

 springs, or in the upper part of the wet ground, pits were sunk in various places. The place of each 

 being marked out, a man was sent to dig each pit, breaking the ground nearly in the direction of the 

 intended drain, six feet long and three feet wide, which is sufficient space to allow a man, or sometimes 

 two, to work freely. The earth was then thrown to the lowest side, and well off from the pit, to prevent 

 the sides from breaking in : these pits were made to the depth of five or six feet, or to a greater depth if 

 necessary, according to the nature of the ground, or until the bed of sand, gravel, or rock, which contained 

 the water, was reached. Sometimes it became necessary, after having gone as deep as a man could work, 

 and wlien no water appeared, to bore down with boring-rods, in order to ascertain at what depth the stra- 

 tum containing the water lay. In some instances, where the surface was wet from a general oozing, and 

 no regular spring appeared, it became necessary to go down to the depth of thirteen feet, when, in break- 

 ing through a thin cake of freestone, not above an inch in thickness, the water burst up, and filled the pit 

 to the brim in the following morning. This species of examination prevents the working at random iu 

 laying out the lines of drains, affords data for judging of the depth and dimensions to which they should be 

 formed; and, by giving a knowledge of the substances to be dug through, enables one to enter into con- 

 tracts with the workmen with greater certainty." {Trans. Highl. Sac.) 



4258. A general idea being thus obtained of the ground to be drained, and men employed to sink the pits, 

 the next operation is to mark out these lines on the ground. In doing this, a hand sketch (fig. 635.) 



indicating the direction of the drains and 

 their depth will be found useful. " On 

 the ground, the lines may be marked in 

 various ways. When the land is in grass, 

 a plough may be made to follow the di- 

 rector, as he walks deliberately along his 

 intended line, a man leading the horses by 

 the head, if necessary, and walking be- 

 tween them. If it is inconvenient to use a 

 plough, the lines may be marked by pins, 

 or small pits, a spade's breadth square, 

 made at convenient distances, by cutting 

 out a turf clean by four cuts of a spade, 

 and laying it upside down at the side of the 

 hole, in the line of the drain." The drains were next dug out, and formed; some of them three feet 

 wide at the top, six feet deep, and two feet wide at bottom, and others of different widths and depths, but 

 generally in the same proportion. The following are Mr. Stephens's directions for building : 



4259. The side walls of the drain, supposing it to be six feet deep, and two feet wide at bottom, " must 

 be well built with dry stone, all laid on the proper bed (and not set up edgeway.s), nine inches thick by six 

 inches high, forming an aperture of six inches square, the covers for which must be sufficiently strong to 

 sustain the pressure of the incumbent weight of stone and earth; and should project, at least, three 

 inches over the inside of each side wall, two feet of stone must be well packed above the cover of the 

 aperture. The first foot of stone above the cover of the aperture may be put into the drains from three 

 to four pounds weight, the upper part must be broken as small as common road-metal, and should be made 



quite smooth or level, so that every part of the drains may have an equal 

 depth or thickness of stone. A thin covering of straw should be laid 

 on the top of the broken stones, to prevent the loose earth from falling 

 through the aperture of the drains. The drains may be then filled with 

 earth, nine inches above the natural level of the surface of the ground. 

 Wells must be sunk along the lowest side of the lines of drains, in every 

 place where the above mentioned depth of six feet does not reach the porous 

 bed that contains water. These wells may be made from five to six feet 

 square, or sufficiently wide to allow a person to work with freedom ; and 

 must be sunk through the impervious strata into the pervious stratum of 

 sand, gravel, or rock, where the water flows freely. The wells may then be 

 filled with small clean stones, thrown in promiscuously, till the stones in the 

 wells come in contact with the stones in the drains. The upper part of the 

 wells above the level of the stones in the drains may be filled with earth." 

 _. {fig. 636.) {Trans. Highl. Soc. vol. vii. p. 222.) 



4260. The stones of which the drains at the bottom of the conduit are to be built, and with which the 

 drain is afterwards to be filled to the depth of two feet or more, as is shown above, should be laid down on 

 the upper side of the line, as near to it as possible, that they may be the more easily handed in. They are 

 laid on the upper side, for the convenience of throwing out the earth on the lower side. It is very desirable 

 that the stones should be, if possible, laid down before the drain is begun to be dug, as it is often neces- 

 sary to build and fill it as fast as it is dug, to prevent the sides from falling m, which, when it occurs, 

 occasions a very great deal of extra work, and the drains themselves are never so well constructed. Ihis 

 most frequently happens in ground under tillage, the sides being more tender than when in grass, where 

 the turf is the means of preserving the sides from the pressure of the earth thrown out, and of the stones 

 laid down When the sides are evidently hkely to fall in before the drain can be built, they may be kept 

 up for a time by a board laid flat to each side of the drain near the top, and cross sticks put in to keep the 

 boards asunder. Circumstances frequently occur, which prevent the stones from being laid down before- 

 hand and they are then brought forward as the work of cutting the drain is going on. Under the eye of an 

 intelligent and attentive director, this may be done without danger ; but, even then, unforeseen occurrences 

 sometimes prevent the possibility of getting the materials forward for several days ; and if any rainy wea- 

 ther intervene, and the drains are in a clayey soil, there is a certainty of slips and falls, occasioning much 

 extra labour, and requiring, in consequence of the additional breadth of the drain, a much larger quantity 

 of stones to fill the opening. Where a piece of drain seems likely to fall in, it should always, it possible 

 be built and filled before night, or the sides kept asunder by means of boards, as before mentioned. ' 

 {Trans. Eight. Soc. vol, vii.) 



4261. Drains may be dug, and, when built, the earth may be filled in by contract 

 work ; but in general day work is to be preferred. " The conduit is built in the 

 bottom of the drain by a confidential person, either a mason, or any other workman 



636 



