116 



STONE DEAINS. 



brush 1 It makes a good drain for a few years, if 

 properly laid, when upon strong and retentive soils; 

 but upon light land it soon becomes choked with 

 sediment, and is rendered useless. Is stone drain- 

 ing superficial ? The blind stone drain represented 

 in the following figure has the same defect as the 

 brush ; that the water, in percolating 

 through it, deposits fine sand, which 

 fills up the interstices, and renders 

 the drain inoperative. Notwithstand- 

 ing stone is not the best material for 

 drains, yet some prefer to use it, even 

 if it is not so cheap, because it is immediately at 

 hand ; and being otherwise a nuisance, its use in the 

 construction of drains answers a double purpose. 

 We shall therefore endeavor to illustrate the proper 

 method of constructing a permanent stone drain. 

 (A) represents three stones placed in 

 the form of a triangle Avith the point 

 down (boards answer a better purpose 

 if laid in the same position). Some 

 will suggest laying them with the 

 broad side down, but experience op- 

 poses this. A certain quantity of water which 

 would pass sluggishly over the broad surface, and 

 leave a sediment after it to obstruct the flow, would, 

 if run through such a drain as is represented in our 

 cut, gain considerably in velocity, the surface to 

 create friction would be less, and sand which might 



