696 



PRACTICE OF ACKICULTURE. 



Pa&tIIT. 



would be liable, when the drain was thus cut, from the thin strata of sand and other 

 loose materials, always found in such casus, to insinuate itself under the bricks, stones, 

 or other substances of which the drain was formed ; to undermine and force them up by 

 the strength of the current, or probably, in some instances, block the drain up by the 

 loose sand or other matters, which may be forced away and carried down by it. In 

 situations of this kind, Johnston observes, it is always the best way to begin just so far 

 down the bank or declivity as, by cutting in a level, the drain may be six or seven feet 

 below the level of the spring ; or of such a depth as may be requisite to bring down the 

 water to a level suitable to convey it away without its rising to the surface, and injuring 

 the lands around it. The rest of the drain, whether it be made in a straight or oblique 

 direction, need not be deep, and may, in many instances, be left quite open ; it should, 

 however, be carefully secured from the treading of cattle, and, where the land is under 

 an arable system of cultivation, also from the plough. Where it is covered, the depth of 

 about two feet may be sufficient. There will not, in such drains, be any necessity for 

 the use of the auger in any part of them. 



4239. Where there is a difficulty in ascertaining the line of the spring, and consequently 

 that of the cross-drain, either from its not showing itself on the surface, or from there 

 not being any apparent outlet, it may, generally, be met with in carrying up the con- 

 ducting drain for conveying away the water. As soon as the operator discovers the spring, 

 he need not proceed any further, but form the cross-drain on the level thus discovered to 

 such a distance on each side of the tail, or terminating part, of the strata, of whatever sort, 

 that contains the water, as the nature of the land, in regard to situation or other circum- 

 stances, may demand. Where, in forming a cross-drain, the line indicated by the spirit or 

 other level is found to be in some places below that of the spring, and where, in boring 

 in this direction, water is not found to follow, it will be necessary to make short drains 

 or cuts of the same depth with the cross-drain, from it quite up to the source of the 

 spring ; for, if the drain be cut below the line of the spring, the possibility of reaching 

 it by means of an auger is lost, as where the under stratum is clay, and there is no under 

 water, the use of the auger cannot be effectual ; and if it be made above the line of the 

 spring, it will be requisite to cut and bore much deeper, in order to reach it, the ground 

 being in general higher in that part : besides, the portion of porous stratum below the 

 drain may contain a sufficient quantity of water to render the land wet, and that may 

 readily get down underneath the trench, between the holes formed by boring, and break 

 out lower down. 



4240. In situations where the extent of bog in the valley betivcen two banks or eminences 

 is so narrow and limited as that the stratum of rock, sand, or other materials, that contains 

 the water, may unite below the clay at such a depth as to be readily reached by the auger 

 (fig. 628. o), it will seldom be necessary to have more than one trench up the middle, 



628 



i§tte% 



40£ 



lHf^^p^W^ : 



well perforated with holes (i) by means of the auger, cross or branching drains being 

 unnecessary in such cases. For notwithstanding the springs, that render the land in- 

 juriously wet in these cases, burst out of the banks or eminences on every side, for the 

 most part nearly on the same level, the reservoir from which they proceed may be dis- 

 covered in the middle of the valley, by penetrating with the auger through the layer of 

 clay that confines and forces the water to rise up and ooze out round the superior edge of 

 it, where it forms a union with the high porous ground. From the drain being made 

 in the hollowest part of the land, and the porous stratum containing the water being then 

 bored into, it is obvious that, the ditch or drain thus formed being so much lower than the 

 ordinary outlet of the springs, the pressure of water above that level, which is the bottom 

 of the drain, must be such as to force that which is under the drain or trench through the 

 holes made by the auger, and in many instances, until a considerable quantity of the 



