DEPTH OF DRAINS. 35 



It is impossible to lay down an inflexible rule, but 

 we may take 3 feet as a minimum, and 4 feet as 

 a maximum. If the soil to be drained rests on an 

 impervious bottom, and is not deeper than 3 or 4 feet, 

 it may be cut through, so that the bottom of the drains 

 may be formed of the said impervious sub-soil. 



In draining bog, too, or mosses, it is best to cut 

 through them if possible ; but this may be a work of 

 time, as it is not always possible to complete such 

 drainage in one operation, owing to subsidence. 



To lessen the expenditure, shallow drains are some- 

 times, in fact often, cut, and the work performed is 

 inadequate, and failure and disappointment result. 

 If the soil requires drainage it is wise economy to do 

 it thoroughly, as it is only by giving ample depth of 

 porous soil that really good timber can be grown. 

 Every inch in depth of drained land gives something 

 like 100 tons of available soil to the acre, a fact too 

 often lost sight of. 



Roots cease to penetrate when they reach the wet 

 stratum, and branch off laterally in all directions. 

 They thus take little hold, and the trees fall with the 

 slightest gale of wind. This is often evident among 

 spruce fir growing on partially drained land. We 

 have seen large areas completely destroyed in one 

 night. This might have been prevented by a greater 

 depth of drainage. 



The distance between the drains is another matter 

 of great importance. As before stated, if too near it 

 results in extravagance, if too far apart in inadequacy. 

 It must be borne in mind that depth will not com- 

 pensate for distance. This has been rendered 



