FOREST EXPLOITATION. 25 



production, provided the exploitation be equably diffused 

 both as to time and space. 



With a view to this there is prepared and it may have 

 been in course of preparation in the forest while some of 

 these data were being prepared in the office a survey, 

 trigonometrical or other, of the forest and of all the 

 plots or patches of which it is composed, varying in any 

 way from what is adjoining, with a diagram of the whole 

 representing each of these, accompanied by a report speci- 

 fying the particulars of each. And with these before him, 

 together with the other data, the forest official entrusted 

 with the w r ork proceeds to what is called I'assiette des 

 coupes, the allotting of the different portions to be felled in 

 successive periods, which is done with provision for subse- 

 quent rectification, if, through anticipated contingencies or 

 unforseen incidents, this should prove desirable. 



Let us suppose the forest under consideration is to be 

 subjected to the regime of timber forest, with a revolution 

 fixed at 120 years, it may be divided into four approxi- 

 mately equivalent portions to be exploited successively in 

 four successive periods of thirty years, but in any or all of 

 which there may be carried on extraordinary operations 

 which occasion may call for, the produce of which are 

 reckoned on as a component part of the annual yield of 

 the forest. 



The portion allotted for exploitation in the first period 

 of thirty years is then on a like principle subdivided into 

 approximately equivalent portions for exploitation during 

 successive periods of say five years. And there is prepared 

 a provisional scheme of annual operations throughout the 

 first sub-period of five years, which, when sanctioned, are 

 followed for a time ; but from time to time the scheme is 

 reviewed, proceeds are compared with estimates, and if 

 necessary the scheme of operations is modified. 



These operations include not only the fellings of cer- 

 tain portions, but the thinnings of others repeated from 

 time to time, and the removal of some of the baliveaux 

 left for seed, and shelter, and shade, a sufficient number of 



