IRRIGATION 26l 



the ditch will be made the desired slant with the mini- 

 mum amount of excavation and nearly uniform in depth. 

 By means of this biped level the ditch can be carried 

 along that course around a hill which will provide the 

 desired gentle slope, with the ditch made at a uniform 

 depth at all points, thus making it possible to open 

 the ditch out with plows or other cheaply operated 

 machines. 



Since it is necessary that field laterals shall be built 

 with embankments so that the surface of the water in 

 them shall rise high enough to flow out on the land 

 when the banks are cut, they must be shallow. On a 

 hillside the earth should all be thrown out on the lower 

 side, but on level or nearly level land it should be 



Figure 158. Biped leveling device. See adjustable leg in Figs. 159 and 160. 



thrown out on both sides. A double moldboard, or 

 listing plow, as shown in Figure 162, will often make 

 a suitable ditch with once or twice passing. More often 

 some such device as that shown in Figure 163 is neces- 

 sary to follow the double moldboard plow throwing 

 the earth out on either side, or the single moldboard 

 plow used to throw two or more furrows either side, 

 forming a dead furrow. Where more depth and a larger 

 ditch is required, the "A" can be used to further open out 

 the first dead furrow and a second dead furrow can be 

 thrown out along the same line, again shoving the 

 loosened earth up on the banks by using the "A." 



The leveling device shown in Figure 161 can be used in 

 grading the bottoms of ditches. Often water flowing 

 in the ditch can be used to secure the desired slant. 



