DRAINAGE. 101 



surface of the retentive ; that a drain driven across the 

 slope in the retentive leaves this issue untouched : whereas 

 a drain driven in the line of the slope cuts every one of 

 these horizontal beds, draws the water to the depth of the 

 drain out of the porous, and stops the overflow. Some 

 one comes forward, and says, " I have seen a case where 

 the alternate beds are parallel, not overlying, perpendicular, 

 not horizontal, and lie in the line of the slope. There 

 your rule will not apply." Quite true ! but Smith's case 

 frequently occurs, and is worthy of a general observation ; 

 yours is very rare, and is not. You must deal with it 

 according to your ingenuity. But perhaps the greatest 

 recommendation of the steep drain is, that the water gets 

 so freely out of it; it is no sooner in the drain than you 

 are rid of it : whereas, in the horizontal drain it lingers 

 lying against the lower side, oozing through the land and 

 inviting attraction. In very steep lands, the general direc- 

 tion of the natural cracks is across the line of slope, for 

 the same reasons of gravity as in landslips, breaks in em- 

 bankments, and other similar cases. Many valleys seem 

 to have obtained their present form by a succession of little 

 landslips, which are still in progress where a stream is 

 washing away the foot. In such cases the steep drain cuts 

 through all the cracks, and relieves them of their water. 



We now come to the conduit. 



If sticks, straw, clods, and the mole-plough have not 

 entirely fled before modern improvements, we should un- 

 worthily detain our readers by occupying a single line in 

 giving them a parting kick. Stones must not be dismissed 

 quite so summarily : they form an imperfect conduit, but 

 we cannot say that in no situation is it advisable to use 

 them. Many wet common lands, on their enclosure, and 

 many of the slopes of moorland hills, when first brought 

 into arable cultivation, are exceedingly encumbered with 

 stones. It is almost as cheap to bury them in 4 or 5 feet 

 drains as to cart them into heaps. We have seen instances 

 where as many stones came out of the drain as would form 



