iJ02 



operation more than one half; and, at 

 the same time, materially forward the 

 growth of the most valuable part of them. 

 We may be sure such increase is consi- 

 derable, when they are not only stiff, but 

 towering fast ; while very few branches 

 require to be displaced. It is to be un- 

 derstood, that the benefit of air chiefly 

 applies to the heads of trees ; as we could 

 never discover that a moderate share of 

 underwood, growing among the stems, did 

 any damage, by reducing the quantity of 

 air, but the contrary. It is admitted, 

 that such must, in some degree, exhaust 

 the soil, but this is abundantly overba- 

 lanced by the advantages before noticed. 



If the training of timber were really as 

 troublesome and expensive as some per- 

 sons believe, still there is a partial mode 

 of doing the business, which may be 

 practised to very great advantage. The 

 method is to select, and mark sucli trees 

 as are wished to stand longest, before the 



