108 OPERATIONS OF DRAINING. 



'* On the other hand, a single swamp, as from B to A, 

 fig. 11, may be produced, and yet one drain at B may 

 be insufficient to remove it. In this case, the water being 

 brought to the surface by more than one channel, it is 

 necessary to form several drains to reach the several beds 

 in which the water is contained, as at B, C, and D. 



" These examples will show, that one rule, with re- 

 spect to the laying out of drains, is not applicable to all 

 cases, but that the drainer should adapt his remedy as 

 much as possible to the cause of injury. One object, 

 however, to be aimed at in all cases of under-draining, is 

 to reach the bed, channel, or reservoir, in which the wa- 

 ter is contained. 



"Before beginning to drain a field or tract of ground, 

 it is frequently well to ascertain, by examination, the na- 

 ture of the substances to be dug through. 



" At the upper part, where the wet tract to be drained 

 appears, or between the wet and the dry, let a few pits 

 be dug. The place of each pit is to be marked out near- 

 ly in the direction of the proposed line of drain, six feet 

 long by three in width, in which space one man, and, if 

 required, two, can work. Let the earth be thrown out 

 to the lower side, and to such a distance from the edge 

 of the pit as not to press upon and break down the sides. 

 Let these pits be cast out to the depth of five or six feet, 

 or more if necessary, so that we may reach, if possible, 

 the porous beds in which the water is contained. Should 

 we find no water, then let us apply a boring-rod, in order 

 to ascertain at what depth the porous substance Hes in 

 which the water is contained. 



" Sometimes water will not be found until we come to 

 a great depth. It may be so deep that we cannot reach 

 it by any drain, or even by boring with the auger. In 

 this case, we are saved the labor of making the drain un- 

 necessarily deep. Sometimes we shall proceed to a con- 

 siderable depth without finding any appearance of water, 

 when, all at once, by breaking through some thin stratum 

 we shall reach it. The water is frequently seen, in this 

 case, to boil up like a fountain, and this affords the assu- 

 rance that we shall succeed in our object. 



