ROTATION FOE COMMERCIAL EIPLOITABILITT. 109 



In practice certain real difficulties are encountered. Th« first 

 consists in the determination of the progressive -value of an average 

 or type tree. This progressive value is the basis of all subsequent 

 calculations. The selecting of the tj'pe-tree requires a great deal 

 of savoir /aire, since there are no two trees that grow alike, espe- 

 cially in an isolated state, and no rule can be laid down to enable one 

 to know that a certain tree 75 years old is the exact counterpart 

 of what a tree, now 50 years old, will become 25 years later. 



In the next place, when marking the trees to fall, it is necessary 

 not only to . know the age of the -various trees from which a selection 

 can be made, but also and chiefly their state of growth. If the 

 veteran of 4 generations or rotations is miaking poor growth, it cannot 

 acquire that additional value which would eonatitute a reason for 

 preserving it for another rotation^ it must therefore fall. But 

 inversely, if the veteran of 5 generations has a full and ample 

 crown, it is certain to acquire, in the course of another rotation, a 

 value superior to the mean value of veterans of 5 generations, and 

 it may therefore be found profitable to preserve it. It is no inconsi- 

 derable advantage to have in a compound coppice coupe a few large 

 trees ; they at once raise the value of the whole coupe. Such trees 

 attract eager purchasers, who would otherwise not have come forward, 

 and thus help in disposing of the small wood.^ 



The loss resulting from the cover of the standards need not 

 cause any great concern, when they belong to valuable species pos- 

 sessing a light cover, like the oak, the ash, the service tree, and even 

 the aspen. Kear the foot of an isolated oak standard it is a 

 common thing to find some young growth coming np. But such is 

 not the case under a beech or hornbeam tree. The injurious effects 

 of cover diminish as its height increases. In any case the loss suk- 

 tained by the underwood can be estimated with the eye, by taking 

 out the difference between the quantity that has actually grown 

 under cover in any given case, and what might have grown up had 

 the cover been absent. 



The impossibility of foreseeing bow the prices of wood and; 

 timber will fluctuate in the future is of little consequence here. 



(1> To understand the foree of this assertion, "the reader must remember 

 that in France the produce of an entire coupe is sold standing wholes»}e 

 Hence the pur .-baser mnst buy the whole q,uantity or none at all. (Iranslator'y 



