DRAINAGE 131 



directly down from the surface would be very likely to bring 

 with it matters which would choke the channel — that which 

 rises into the bottom of the drain is as clear as spring water, (is 

 spring water in one sense,) and can only obstruct the drain by 

 washing into heaps the earth that it flows over in its course 

 through the drain. 



It is very well to cover the stone-work with the smallest quan- 

 tity of shavings or leaves that will prevent the earth with which 

 the trench is filled from rattling into the " eye," but this should 

 be immediately covered with the stiffest subsoil at hand, which 

 should be trampled or rammed down so solidly that no strealms of 

 water and no vermin can work their way through it. Sods make 

 a very good covering when they are first laid, but they soon decay, 

 and afford the best possible material for obstructing the drain. 

 If small stones are to be used at all they should not be placed 

 over the drain, where they can only do harm ; but below it, where 

 they protect the earth against the action of the stream, and al- 

 low the water of saturation to rise freely into the drain. 



The different methods of laying stones so as to form a chan- 

 nel are too well understood to need illustration, and the selection 

 of one or another must depend very much upon the character 

 of the stone to be had for the purpose. In every case, they 

 should be so laid that they can neither be undermined by the 

 stream, and made to "cave in," nor be forced out of their places 

 by the weight of the filling above them. 



If the chief object is to get rid of a large amount of stone, this 

 may be best accomplished by digging very wide trenches, wide 

 enough to use a plow for loosening the ground to the whole 

 depth, and dumping the stones in from a cart, merely leveling 

 them off within one and a half or two feet of the surface, and 

 packing the heaviest soil over them. In a very large drain of this 

 sort, the water will always find a passage, unless it is so carelessly 

 laid that surface streams flow in. 



A very good way to get rid of useless stone walls is to dig a 

 trench at one side of them and throw them in — finishing off" the 

 top as above directed. 



