SUBIRRIGATION AND SUBSOILING. 



423 



The Asbestine System.— If the water-supply be 

 limited, or difficult to obtain, this plan stands well at 

 the head. It consists of cement pipes, generally three 

 inches in diameter, but varying from two to four inches, 

 that are made in a continuous line in the bottom of 

 trenches with small openings at intervals, in which 

 wooden plugs or nipples with quarter-inch holes are 

 inserted. A modified form for use in orchards, where 



FIG. 107 — DIAGRAM OF SUBIRRIGATED FIELD. 



the tree roots would be likely to trouble by clogging 

 the holes, has square openings about six by three 

 inches, over which a piece of tile of a size that will fit 

 evenly down over the opening is laid. These tiles are 

 laid from fifteen to twenty inches below the surface, and 

 although they will work if given considerable fall, they 

 distribute the water in a more satisfactory manner if 

 they have at best but a slight and even slope. In the 

 orchards they are laid between alternate rows, and the 

 holes are from fifteen to thirty feet apart. The 



