PBINCIPAL KINDS OP EXPLOITABILITT. 43 



rate of profits and its essential character is only to benefit the 

 producer. The first regards solely the public good, the second the 

 interest of the individual owner or owners. It is for this reason that 

 we will style the first Economic Exploitabilitt, the seconid 



COMMEKCIAL EXPLOITABILITr. 



As the standing crop grows on, the quantity and usefulness of the 

 wood produced increase, but each in a different ratio. It behoves us 

 then to study each separately. Sometimes we may desire to obtain 

 only either the maximum quantity of material or the maximum 

 degree of usefulness, as vould happen if one of the two varied very 

 little or not at all. Hence, following the practice of writers on 

 forestry, we have Istly. Quantitative Exploitability, which aims 

 solely at producing the largest quantity within a given time ; 2ndly. 

 QUALTTATIVK ExPLOiTABiLiTT Or the Exploitability relative to the 

 degree of usefulness of a given quantity of produce ; and 3rdly. the 

 Exploitability combining the characteristics of the two preceeding, 

 which we will term National Exploitability, and which has for 

 its object the production of the largest quantity of the most useful 

 produce. These are only three specific kinds of Economic Exploita- 

 bility. Under the other head there is only the single specific kind 

 which we have designated Commercial Exploitability, and which has 

 reference to the profits accruing on capital invested. It is by the 

 aid of this Exploitability that the selling price of forests is estimated. 



As an exceptional case forests are required to perform for man- 

 kiad other offices than that of producing wood, as, for instance, the 

 preservation of the soil, protection against avalanches, shelter fit>m 

 high or dry winds, &c. Under these circumstances, the maximum 

 benefit derivable from a forest is realized only when the trees have 

 attained their maximum gi'owth, in other words, the limit itself of 

 their life, or, to say the least, the beginning of decay. The generic 

 name we will give to the kind of Exploitability which procures us 

 these indirect services will be Peotecttve Exploitabilitt. 



It is easy to conceive that there can be other kinds of Exploita- 

 bility depending on the object with which a forest may be managed, 

 such as the production of resin, pastures, &c. But these are ques- 

 tions that present themselves only under exceptional circumstanceB 

 and their solution is as a rule obvious or at least easy. 



