SOIL WATER 93 



99. Kinds of Drains. The most universal kind of drains 

 are the surface ditches. These are useful in many cases ; 

 but are not so desirable as under-drains where the latter 

 can be used. Surface drains that are to be permanent 

 should usually be made with sloping sides, so that they 

 can be driven across. Stone under-drains are often made 

 in regions where the land is stony. They require much 

 more time for construction than tile drains. At the present 

 relative prices of tile and labor it is probable that tiles 

 are cheaper than stone. Poles and many other devices 

 have been employed. 



100. Laying Tile Drains. The method of laying drains 

 can be learned from books, or better by seeing it done, 

 or best by doing it. There are a few points that are often 

 neglected. 



The tile should be hard-burned and should not be too 

 small. It is doubtful whether tile smaller than three-inch 

 should ever be used. Some manufacturers in Illinois 

 the state that uses the most tile do not make any tile 

 smaller than four inches. Their experience is that farm- 

 ers who use these sizes are so well pleased as to buy more, 

 while those who use the smaller sizes are less likely to 

 be satisfied. It is much more difficult to lay small tile 

 accurately, and they are much more likely to get out of 

 place. A slight movement is sufficient to break the connec- 

 tion of the openings. The small tile are more likely to fill up. 

 If possible, the lower part of the line of tile should have 

 a steeper fall than the upper part, so as to guard against 

 filling up with silt. For the same reason, the outlet should 

 always be above standing water. 



A map of the farm showing the location of drains should 



