266 DIEECT aowiNff. 



is a valuable commodity, and so on, the distance required between 

 the lines may be so great that this rule could not be followed. In 

 'that case half the distance would be too great and the ratio must 

 be accordingly diminished in proportion to the extent to which 

 failures are to be apprehended. 



§ 2. Size of the patches. 



The dimensions of the patches are amenable to the same considera- 

 tions as those which regulate the width of strips ; but as in th& case 

 ot strips the seedlings receive extraneous shelter only on two sides, 

 whereas here they receive it equally on every side, the cross dimen- 

 sion of the patches may safely exceed the width that would be given 

 to strips under identical conditions of soil, locahty, species employ- 

 ed and surrounding vegetation. One of the rare exceptions to 

 this rule will occur when on steep slopes the lines of patches run 

 up and down hill (see § 3). In that case, to minimiseithe chaibces 

 of erosion, the patches should be as small as other considerations 

 will allow. No danger need be apprehended for the seedlings in 

 these small patches from the surrounding vegetation, which on 

 such steep slopes is seldom dense save under standing forest. In 

 the exceptional case just referred to, the side of the patch will 

 vary from 1 to 2 feet, otherwise it will generally range from 2 to 

 4 feet, from 2 to 3 feet being the usual figure. 



§ 3. Direction of the lines of patches. 



The dimension of a patch in every direction is small enough for 

 the surrounding spontaneous vegetation to afford complete proteo- 

 tion to the seedhngs as long as they do not top that vegetation. 

 Hence, until this stage is reached, it is of no consequence at all, as 

 far as injurious atmospheric phenomena are concerned, in what 

 direction the lines run. It is only when the seedlings have grown 

 up that they form a series of parallel lanes, along which the wind 

 may sweep with unchecked violence if the directions are coinci- 

 dent, in the plains, therefore, it is quite sufiicient to run the lines 

 of patches at right angles to the direction of dangerous winds. 



In the hills the hues of patches should whenever possible, follow 

 contour lines, irrespective of every other consideration. But when 

 the ground is so steep and bare of ti-ees or shrubby growth as to 

 afford no foothold for the workmen, each patch would require 

 a ledge to be cut immediately below it for the workman making it 

 to stand on. If the lines of patches were close enough together, 

 each line would serve as a point d'appui for the preparation of the 

 line next above it. But the lines are seldom, if ever, close enough 



