IMPROYEMEKT OF SOILS. 33 



lets, which the capillary power of the soil is thus unable 

 to feed. 



Another circumstance which will occasionally haye an 

 influence in regulating the depth, is the degree of slope 

 which can be obtained, according to the surface-levels of 

 the district. Theoretically, water will flow if there is 

 but the smallest possible deviation from a horizontal line, 

 but in j^ractice this is not sufficient, for it imjolies a 

 perfectly smooth and regular bed, a condition which can- 

 not be expected to exist in land-drains. The water 

 should not pass too quickly through the soil, before it 

 has time to deposit its nutritive ingredients, but neither 

 should it be allowed to stagnate, as it will do if the 

 drains are deeper than it can readily permeate, or if the 

 fall is insufficient to induce a free discharge. When the 

 drains are sufficiently active they will not allow the water 

 to stand for any length of time on the surface after the 

 most heavy rains. 



For purposes of cultivation the drains should seldom, 

 if ever, be laid at a less depth than three feet from the 

 surface of the ground. In grass-lands two and one-half 

 feet may be sufficient, but where other circumstances are 

 favorable, three feet should be the minimum depth. 



The laying of the pipes should be entrusted to a careful 

 workman, who is paid days' wages, as more attention in 

 the performance of the work is thus insured than when it 

 is done by the drainer at piece-work. 



It is very important that the pij^es should be large 

 enough for the quantity of water they have to discharge. 

 If the fall is considerable, a pipe of less dimensions will 

 suffice than where the inclination is smaller. In j^ractice, 

 after the depth and interval of the intended drainage have 

 been determined bv trial holes in the manner described, 

 and after any particular sjorings of water have been dealt 

 with by special conduits taken through the wet spots 

 thus created, and after all old water channels have been 



