FARM DRAINAGE AND IRRIGATION 213 



chased for about $15. For very small jobs a home-made water level will 

 serve the purpose. This consists of a section of gas pipe about three feet 

 long, with a glass tube attached to each end by means of corks or rubber 

 tubing. The glass tubes should be at right angles to the pipe. When 

 filled with a colored solution and held approximately level, the operator 

 sights across the top of the colored solution as it appears in the two glass 

 tubes. 



Establishing the Grades. The drainage lines are laid out by driving 

 stakes at intervals of 50 to 100 feet, about 18 inches to one side of the 

 center of the ditch. These stakes are driven into the ground until the tops 



A LOW-PRICED TILE DITCHER. 



are only two or three inches above the ground level. By use of the level, 

 the elevation of each is ascertained. The next step is to calculate the total 

 fall of the line and determine whether the grade is to be uniform or whether 

 it must be changed for a portion of the course. This will depend on the 

 variation in the slope of the surface of the ground. If the slope varies 

 much, two or more grades may be necessary in order tiiat the drainage pipe 

 may be placed at the desired depth beneath the surface of the ground. A 

 single grade may result in the tile being too deep over a portion of the course, 

 thus necessitating expensive excavating, or it may be too shallow to provide 

 effective drainage. These difficulties are avoided by suitable changes in 

 the grade. 



Grade stakes projecting about 18 inches above the surface of the 

 ground are set one beside each of the stakes designating the level. These 



