THE IRRIGATION AGE. 197 



every hundred feet or so, according to the slope of the ground. 

 Where the surface is broken they will be irregular and will follow 

 along the ridges. These ditches should also have a slight fall, the 

 steepest slope being at right angles to them. Such ditches are 

 usually simply furrows made with a heavy mold board plow, and, 

 where the crop is grain, they are filled back by the plow before 

 harvesting. These ditches, being cut at convenient points, allow the 

 water to run out and spread over the adjacent land. The water thus 

 released at once begins to follow the lines of quickest descent, and in 

 so doing spreads out over the ground as it proceeds, dividing into 

 numerous branches or rills as it increases its distance from the open- 

 ing in the ditch. For the purpose of facilitating its spreading and to 

 insure its thorough application to every portion of the surface, the 

 irrigator follows its course, and by means of a long-handled shovel 

 guides it to every portion of the field. This guiding is done by mov- 

 ing a few shovelfuls of earth here and there, and thus separating the 

 various small rills and starting the branches in different directions. 

 In this way the irrigator follows the water through the field and 

 prevents its collecting in the depressions, leading it out upon such 

 points as would without his assistance be missed by the water. 

 Where only one operator is at work it is usually advisable not to 

 make very many openings in the ditch at one time, since to do so 

 may result not only in a waste of water through his concentration 

 into larger streams which rapidly escape to lower ground where it 

 may not be needed, but its concentration for long periods in the 

 depressions of the surface is likely, through oversatu ration, to 

 damage the crop at those places. When the area which can be most 

 conveniently irrigated from the openings thus made has been suffi- 

 ciently moistened, the latter are closed by throwing in a few shovel- 

 fuls of earth, and similar openings are made at other points, the same 

 process being there repeated, and so on until the irrigation of the 

 whole area has been completed. 



The entire operation is characterized by much greater simplicity 

 than would be supposed by one unfamiliar with the practice of irri- 

 gation, only presenting feature of serious inconvenience when the 

 surface to which the water is applied is very irregular and broken, 

 the slopes steep, and the soil loose and friable to such an extent as to 

 be easily eroded. Even under those circumstances no real difficulty 

 is presented, though the work is thereby rendered slower and more 

 tedious through the greater care required in handling the water, and 

 because a large volume can not be handled at one time on account of 

 the greater liability of washing away the top soil and thereby injur- 

 ing the land. Fortunately, however, most of the farming land in the 

 arid region has a comparatively uniform surface, and this difficulty is 

 therefore not frequently encountered. The land so preponderates 



