ARBORICULTURE. 383 



but the former, having large and compound branches, should be 

 pruned at an earlier age than the latter, or before the lateral 

 shoots are more than two inches in diameter. When the branch 

 to be taken off is several inches in diameter, the wound is so 

 large, the excavation of resinous sap so great, and the heart wood, 

 or the vessels which constitute it, so indurated, as to render the 

 perfect union of the new and the old wood less certain than in 

 young branches, all which make the removal of large branches 

 productive of more evil than service to the growth of the tree 

 and quality of the timber. On the contrary, when the pruning 

 of the, pine is altogether neglected, and the dead or rotten stumps 

 or snags of branches are left to be imbedded in the wood, or to 

 form cavities for the accumulation of water or other extraneous 

 matters in the substance of the stem, all the purposes of profit 

 and of pleasure are sacrificed to neglect or unskilful culture. 



Judicious thinning may be said to be productive of the same 

 valuable effects to a plantation of timber trees in the aggregate, 

 as those which judicious pruning produces on every individual 

 tree composing it : by the admission of a proper circulation of 

 air and the solar rays, and permitting the free expansion of the 

 essential lateral branches of the trees, as well as by preventing 

 an unnecessary waste or exhaustion of the soil by the roots of all 

 supernumerary trees. 



The great advantages of judicious thinning are not confined to 

 the object of obtaining the largest quantity of timber of the best 

 quality on a given space of land in the shortest space of time ; 

 but the produce of the trees thus thinned out ought to afford a 

 return sufficient to pay the expenses of culture, interest of capital, 

 and the value of the rent of the land. In many instances the 

 profits arising from the thinnings of well managed woods have 

 covered these charges before the period of twenty years from the 

 time of planting. The time at which the process of thinning 

 should be commenced, depends on the like causes as those 

 which regulate pruning, and need not here be repeated. 



In general the freest growing plantations require to have a 

 certain number of trees taken out by the time they have attained 

 to eight years of growth from planting. On forest-tree soils of a 



