Book III. DRAINING BOGS. 696 



the wetness from both. But where the impervious stratum dips or declines more to one 

 side of the hill or elevation than the other, the water will be directed to the more de- 

 pressed side of that stratum ; the effect of which will be, that one side of such rising 

 ground will be wet and spongy, while the other is quite free from wetness. 



4236. Where water issues forth on the surface at more places than one, it is necessary to 

 determine which is the real or principal spring, and that from which the other outlets are 

 fed ; as by removing the source, the others must of course be rendered dry. When on 

 the declivity or slanting surface of the elevated ground from which the springs break 

 forth, they are observed to burst out at different levels according to the difference of the 

 wetness of the season, and where those that are the lowest down continue to run, while 

 the higher ones are dry, it is, in general, a certain indication that the whole are connected, 

 and proceed from the same source ; and consequently that the line of the drain should be 

 made along the level of the lowermost one, which, if properly executed, must keep all 

 the others dry. But if the drain were made along the line of the highest of the outlets, 

 or places where the water breaks forth, without being sufficiently deep to reach the level 

 of those below, the overflowings of the spring would merely be carried away, and the 

 wetness proceeding from that cause be removed ; while the main spring, still continuing 

 to run, would render the land below the level of the bottom of the drain still preju- 

 dicially wet, from its discharging itself lower down over the surface of the ground. 

 This, Johnston states, was the custom, until Elkington showed the absurdity of the 

 practice of drainers beginning to cut their trenches wherever the highest springs showed 

 themselves between the wet and the dry ground, which not being of a depth suflBcient to 

 arrest and take away the whole of the water, others of a similar kind were under the 

 necessity of being formed at different distances, to the very bottom of the declivity : 

 these being afterwards in a great measure filled with loose stones, merely conveyed away 

 portions of surface water, without touching the spring, the great or principal cause of 

 the wetness. The effects of drains formed in this manner he asserts to be that of ren- 

 dering the surface of the land in some degree drier, so long as they continue to run with 

 freedom ; but as they are liable soon to be obstructed and filled up by sand or other 

 materials, the water is often forced out in different places and directions, and thus 

 renders the land as wet as before, if not wetter. In addition to this, it is a more diffi- 

 cult task to drain the ground a second time in a proper method, from the natural appear- 

 ance of the ground being so much changed, and the bursts of the old drains, as well as 

 the greater difficulty of ascertaining the real situation of the springs. 



4237. It may sometimes happen, however, that where the highest are the strongest outlets, 

 they may be the maiii or leading springs ; those which show themselves lower down in the 

 land being merely formed by the water of the main spring overflowing, and finding itself 

 a passage into the earth through an opening in the surface, or through the porous materials 

 of the soil near to the surface, and being obstructed somewhat further down in the 

 ground by some impervious stratum. This circumstance must, therefore, it is observed, 

 be fully ascertained before the lines for the ditches or drains are marked out. 



4238. In cases where the banks or rising grounds are formed in an irregular manner 

 (Jig. 627.), and, from the nature of the situation, or the force of the water underneath, 



627 springs abound round the bases of 



the protuberances, the ditches made 

 for the purpose of draining should 

 always be carried up to a much 

 higher level in the side of the ele- 

 vated ground than that in which the 

 water or wetness appears; as far 

 even as to the firm unchanged land. 

 By this means the water of the 

 spring may be cut off, and the 

 ground completely drained ; which 

 would not be the case if the trench 

 or drain were formed on the line 

 of the loose materials lower down, 

 where the water oozes out, which is 

 liable to mislead the operator in 

 forming the conducting trench, or 

 that which is to convey the water 

 from the cross-drain on the level 

 of the spring to the outlet or opening by which it is discharged. But where the main or 

 principal spring comes out of a perpendicular or very steep bank, at a great height above 

 the level of the outlet into which it may discharge itself by means of a dram, it wiU 

 neither be necessary nor of any utility to form a deep trench, or make a covered drain, 

 all the way from such outlet up to it; as from the steepness of the descent the water 



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