58 



prove that form-factors vary chiefly with the height of the 

 trees. 



CAtCULATIOS OF THE EXPLOITABLE AGE. 



General rules. — In order to calculate the exploitable age 

 of a tree it is necessary to ascertain the girth or diameter at 

 which it furnishes the greatest quantity of the most useful 

 material that is required. As a rule the price is the best gauge 

 of the utility ; so that in most cases it may be said that trees 

 are exploitable when, after deducting all expenses of exploita- 

 tion, the price they realize per unit of volume is the highest 

 obtainable. 



It not infrequently happens in India tliat it hag to he decided — ^not what is the 

 priofi or what is the most useful produce but— whether the people in the vicinity of 

 the forest or the general commanity should enjoy the produce. The people in the 

 neighbourhood may require small wood-fuel and pasture for their cattle ; the fseaeral 

 community, large timber. As a rule, the decision goes in favour of the local wants, 

 though this could not always be defended from a purely economic point of view. It is, 

 moreover, frequently overlooked that, in growing large timber smuU timber from the 

 thinnings and branches is also available generally in as great abundance as can he 

 consumed within the radius to which it may be profitably transported ; when more 

 grazing can he provided than if the crop were cut when young and the forest, conse- 

 qnently, can he closed more frequently to cattle. 



By price is here meant, of course, the net price of the 

 trees when standing in the forest, after deduction of all cost 

 of felling and extraction. The price must be calculated per 

 unit of volume in the rough, unless where there is only a 

 demand for standing trees. When poles or timber in the 

 rough or logs are sold, the price realised per cubic foot for 

 differently sized pieces directly indicates the size of the trees 

 which are most useful and which will bring in the highest 

 revenue ; provided that the cost of extraction is in all cases 

 previously deducted. 



It will often he found that, owin^ to defective means of transport and to the 

 greater cost consequently involved in extraction, the net price of large logs is lower 

 than that of small, although the selling price of the former when delivered to the 

 consumer may be very much ni<;her. 



When the size of the trees is calculated from the 

 ruling price for converted timber, planks, sleepers, etc., or 

 manufactured articles, the loss in conversion must be cal- 

 culated in order to ascertain the cost per cubic foot, and that 

 size should be ascertained in respect of which the loss is 

 least. Almost invariably the loss will be least when the 

 trees are largest. 



