63 PLANTING. 



spruce, and silver tirs, to attain to their maximum of timber growth, on 

 soils of an average quality adapted to their habits ; and as the above trees 

 may profitably occupy the soil for twenty or thirty years more, or without 

 ceasing to produce timber annually for that period, the thinning- now 

 should depend on, or be regulated by, the circumstances of demand for 

 the produce, more than for the benefit of the individual trees which 

 remain. 



In the above details of thinning, it will seem to demand an explanation, 

 why certain trees of the lowest value at fifty years' growth should have 

 been left apparently to encumber the ground, while trees of a value equal 

 to these are cut down at ten years' of growth. The answer to this question 

 brings us back again to the difficulties before alluded to, of giving any 

 data, or rules applicable in all cases, founded on number, size, dis- 

 tance and time, for the execution of the different processes of culture, 

 relative to assisting and controlling the functions of vegetable life, so as 

 to produce a given result, or obtain a specified quantity of timber from 

 certain trees under different circumstances of soil, site, local climate, and 

 culture. 



If all trees were produced from seed with the same degree of constitu- 

 tional strength, and were the soils on which they might be planted of the 

 like nature throughout, and under equal circumstances with regard to 

 moisture and exposure, as well as to every other influential point, then 

 statical rules of practice for the culture of trees might with equal certainty be 

 given, and of as general an application to suit every variety of case, as 

 those for the execution of any mechanical art : but the reverse of all this is 

 the fact; and every variation in the soil, and in the exposure and growth 

 of the trees, must be met with a corresponding variation in the process of 

 culture, as regards the number of trees to be thinned out, the distances at 

 which they should stand, and their size and age. The trees above 

 mentioned, which at fifty years' growth were not of greater value for tl 

 purposes of timber, than several trees thinned out at ten, assisted tl 

 growth of the more valuable trees, which immediately or more remote!] 

 adjoined them, by the shelter they afforded against cutting winds, an< 

 by ameliorating the local climate, to that degree as to fully warrant 

 their continuance. Those trees which were of equal value to these when 

 cut down at ten years' of growth, stood so close to others of greater pro- 

 mising value as to injure the growth of both, and had they been Millerec 

 to remain, would have prevented some of the most valuable trees of tlu 

 plantation from attaining to perfection. Thus, on the one hand, by 

 moving the former description of plants, the most valuable trees ai 

 promoted in growth, and on the other preserved from injury, by sulferii 

 iltiable ones to remain. 



Various tables have been calculated to assist in deciding on the numbei 

 of trees to be thinned out of plantations at stated periods; one of these by 

 Mr. Waistell*, appears to be brought to as near a correct average, as the 

 nature of the subject will permit. 



' The following table shews the number of trees to be cut out in thinnin 

 woods, and the number left standing at every period of lour years, froi 

 twenty to sixty-four year-, reckoning that the distance of trees from t-ac 

 other should be one-fifth of their height, and that the trees should lun 

 increased twelve inches in height, and one inch in circumference annually, 

 and to have been at first planted four feet apart.' 



* Transactions of the Society of Arts, vyl, xxvi., and AVithvrs's ( Memoir on planting 

 and rearing Forest-trees,' p. 37, 



