RECLAMATION OF THE SOIL. 



135 



reduce the fall ; or the base and sides of the drains must be 

 protected by a facing of stone, or fascines ; in some cases the 

 base may be terraced. 



a, a. Contour lines, 

 c, c. Wiiter parting. 

 h. Feeders. 



Fig. 16. 



c. Leaders. 



d. Main drain. 



(The figures 170, 160, 150, and 140 give the elevation in feet above sea-level.) 



The maximum gradient which is admissible depends on 

 the nature of the soil. Where the latter is of middling con- 

 sistency an average fall of 1 per cent, would probably be 



