DRAINING. 



75 



Draining. If the field has a considerable descent, care must be 

 ** "~'f~' taken to have the drains nearly horizontal ; for, if they 

 have too quick a fall, they are apt to excavate and burst 

 up. In such cases, as the drain only receives water from 

 the upper side, it is advisable at times to puddle along 

 the lower side, that the water may not, by running over 

 through the subsoil, injure the lower part of the field. 



When the hollow drain is carried through running 

 sand, it is necessary to support the sides of the trench by 

 boards and props, which are removed forward as the work 

 proceeds. In making sod drains also, loose earth or sand 

 is sometimes met with, in which cases the pipe must be 

 lined with turf to prevent its choking, the loose earth being 

 previously cut out to a sufficient width to admit of this. 



The mouths of hollow drains being much frequented 

 by cattle, should be formed with stone, or otherwise pro- 

 tected; and too many of them ought not to be run toge- 

 ther, lest an obstruction in the main, cause an extensive 

 mischief. 



CHAP. III. Of Drying Spring Groundt by Draining the 

 Strait. 



Having now shown the principles bv which the ro- 

 claiming of watery lands is effected, when the water 

 lodges on the surface, or is injuriously stagnated in the 

 soil, we proceed to the third division of our subject, in 

 which we mean to consider those cases where the ground 

 is hurt by the oozing of subterranean waters, or the flow- 

 ing of springs, producing wet spouty land, bogs, and 



unds. 



Origin of 



This subject is much more complicated tljan the other 

 two: it constitutes one of the most beautiful, and per- 

 haps the most important, applications of the doctrine of 

 hydraulics ; it is surprising, therefore, that it has been so 

 Kttle attended to by scientific men. Though many of 

 them have written on the subject of springs, few have 

 endeavoured to render their speculations so far useful, as 

 to lay down a few principles for the benefit of the intel- 

 ligent farmer, on a subject in which all are so much 

 interested. 



The first person in this country to whom we are in- 

 debted for a practical and intelligent treatise on the na- 

 ture of boggy grounds, and the method of curing them, 

 by relieving the subjacent waters, was Dr James Ander- 

 son, in his Essays relating to Agriculture and Rural Af- 

 fairs, printed in the year 1775. About the same time, 

 Mr Joseph Elkington had fallen upon the method of 

 tapping subterraneous waters, by means of the auger, in 

 the course of draining his farm in the county of Warwick. 

 Mr Elkington was, in consequence, much employed as a 

 practical drainer ; and his success was so great, that the 

 Board of Agriculture, in the year 1 795, proposed that a 

 parliamentary reward should be given to him for his dis- 

 covery. An account of his method was afterwards given 

 by Mr John Johnstone, and published by the Board, from 

 which much useful practical information may be obtained. 



Springs are formed, or have their origin in the diffe- 

 rent strata of the earth by the rain water which falls 

 upon it, sinking into those which are of a porous nature, 

 and descending until they meet with a bed of clay, 

 close gravel, or impervious rock ; upon this it cither 

 passes along down the declivity of the bed, soaking 

 through the porous matter which lies over it, or it col- 

 lects, as in a reservoir, until it is emitted at some part of 

 the surface of the ground, forming all the different phe- 

 nomena of springs, &c. which are so often met with. 



Hence we see, that in countries of deep sand or gravel, Draining, 

 without beds of clay to force the water to the surface, ^~~ 

 abundant springs are not to be met with ; and again, the spn nt ? 

 deep clay countries arc equally destitute of spring water grounds, 

 until we descend through the clay into a bed of sand or 

 other open stratum, the only situation in which the 

 water can flow in abundance, and in which it is only 

 made to pass horizontally by a bed of clay, or other im- 

 pervious matter opposing its further progress downwards. 

 If this bed or floor of clay, instead of coming to the sur- 

 face, should have its lower edge terminate in the sea, a 

 deep lake, or the bank of a river, the water which has 

 descended to it will find its way into these natural recep- 

 tacles, without ever making its appearance on the surface 

 of the land ; and there can be very little doubt but that 

 much of the water which falls on the dry land escapes in 

 this way without being perceived. 



But if, from the unevenness of the surface of the land, 

 and the abruptness of the strata, the lower edge of the 

 impervious bed should any where reach the surface, as is 

 frequently the case on the sides of hills, in deep dingles, 

 &c. the water, which was collected in the porous strata 

 above, will there make its escape ; and as a considerable 

 time must be required for its passage through the ob- 

 structed interior channels, the intervals of drought will 

 not always be sufficient to admit of the whole being de- 

 livered before a new supply comes again from above. In 

 this manner, a frequent, or even continual, oozing of wa- 

 ter may be formed ; and if it be not confined to a narrow 

 channel, but allowed to spread over the grounds below, 

 plots of watery land will be formed, and in time covered 

 with aquatic vegetables, which, by their decay, are con- 

 verted into peat or bog. 



This case has been denominated descending waters by 

 some writers, and forms the first class of boggy ground 

 arising from springs. Plate CCXXXIII. Fig. 8. repre- P '- ATE 

 sents a plan and section of a case of this kind. AB is a cf xx * ln> 

 bed of deep clay, extending from the brook at A, back 

 under the hill DE. CD is a bed of sand or open stra- 

 tum covering the clay, and is covered in its turn by the 

 different porous strata forming the hill or bank CDE. 

 These strata imbibing the rain-water which falls on the 

 hill, allow them to descend until they reach the line CD, 

 where 'their farther progress in that way is stopped by 

 the bed of clay BA. They accordingly accumulate in 

 the sand, until the increasing pressure forces them through 

 the different pores and fissures in the horizontal direc- 

 tion DC, and they issue at Cc, the foot of the porous 

 bank, in springs of pure water, which run forward in rills 

 to the brook Aa, which, if an open channel is preserved 

 for them, are not likely to do much injury to the farmer. 



But it usually happens, that the edges of the porous 

 strata EC, have been worn and broken down by the vi- 

 cissitudes of weather or other causes, and their rubbish 

 or detritus carried forward over the low ground CA, 

 ca, forms a porous soil over the clay bottom. In this case, 

 the water which issues at the springs Cc, instead of pas- 

 sing off in rills, soaks into the porous soil, and keeps it 

 constantly drenched with wet, so as often to injure a 

 great extent of ground below, especially if the subsoil be 

 shallow or retentive, as is commonly the case with lands 

 not ameliorated by cultivation. Many millions of acres 

 in the upland countries of these kingdoms are still in 

 this condition, their surface covered with peat moss or 

 bog, which nevertheless might be drained at an cxpence 

 inconceivably small. 



