192 



FARM DEVELOPMENT 



drains with a drainage system complicates the problem, 

 it is sometimes wise to use profile paper in making what 

 is termed a profile of each of the proposed ditches. 



The profile is a great help in devising the proper 

 grades for long drains on very flat areas so as to have 

 them sufficiently deep in the lower places, not too deep 

 where the digging would be considerable and yet have 

 the most practical grades for effectually carrying off the 

 water at the least expense for construction. 



How to make a profile. The figures representing the 

 height of the successive stations above datum, as re- 

 corded in Figure 81, are used to show the surface of the 



Figure 83. Profile showing surface and the grade line of the ditch, thus Riving the 

 depth of the ditch. 



land at each station. Figure 83 shows how the heights 

 above datum are mapped into a profile to show the sur- 

 face of the earth along the line of the ditch, from its out- 

 let to its head. This line having been mapped in, an- 

 other line beneath the surface can be drawn, showing 

 the bottom of the ditch, whether tile drain or open ditch. 

 By careful inspection and measurement, or by counting 

 the lines, this line representing the grade of the ditch 

 can be so placed that the ditch will not be made un- 

 necessarily deep and expensive, nor yet too near the sur- 

 face at any point. It will be observed that points have 

 been chosen along the line of the ditch where the grade 

 is slightly changed. Between these points straight lines 

 are drawn, showing that the grade is to be uniform 

 between the chosen points. By using a soft pencil, 

 these points for changing the grade may be located and 

 trial lines made, and, if not in the right place, they may 



