120 



DRY FARMING CONGRESS. 



tions a twenty-foot roadway would be ten inches higher in the center 

 than at the edge where the slope becomes greater to the bottom of the 

 ditches. The slope from the edge of the crown to the bottom of the side 

 ditches should have a fall of at least four inches to the foot. 



Side Ditches. 



Open side ditches are also absolutely necessary to thorough surface 

 drainage. The bottoms of these ditches must be carefully graded so that 

 all water falling on the road bed will be quickly carried off rather than 

 be left in pockets along the road sides to gradually soak away, thus, 

 softening the road. 



For the safety of travellers and also from the point of economy of 

 first cost and maintenance, these side ditches should be made broad 

 and shallow rather than deep and narrow. The water should not be 

 conducted for long distances as it increases the washing and makes the 

 ditches too deep at the outlet end. 



Underdrainage. 



Tile drainage will greatly improve the conditions where the ground 

 water rises to a level of from eighteen inches to two feet of the surface. 

 Water seeping from springs or irrigation ditches can be readily removed 

 by carefully placed tile drains. 



Under ordinary tile drainage conditions, one line of tile placed just 

 inside of the open ditch under the road bed is sufficient. This line is to 

 be placed at a depth of from three to four feet, according to the soil 

 conditions. Exceptionally wet places sometimes require two lines of tile, 

 one on either side. Seepage water usually comes from one side of the 

 road; this can be cut off by placing a line of tile as heretofore described 

 on the side of the road nearest the source of water supply. 



For carrying water distances of not over 1,000 feet a four-inch tile is 

 large enough. For distances from 1,000 to 1,500 feet a six-inch tile is to 

 be preferred and for greater distances an eight-inch. The size of tile, 

 however, will vary with the soil conditions and grade and not entirely 

 by the length of the line. 



In tile drainage, great care must be exercised in locating it true 

 to grade. The tile should be placed below the frost line. It must be 

 large enough to carry all the water. The outlet must be protected to prevent 

 it from being washed out and it should also be covered with grating to 

 prevent the entrance of various small animals. Above all, first class tile 

 only should be selected. 



Grade of Road. 



A grade may be reduced by going around a hill or by zigzagging 

 up the slope. For ordinary roads the road bed must conform with the 

 natural lay of the surface over which it passes. Hills which are short 

 and steep may usually be graded down to better advantage than to pass 

 around them. Increasing the length of a road adds to the cost of con- 

 struction and of transportation, while cutting down a hill adds only 



