94 



tenth of the area, every ten years. We may suppose that nnmber of years to be the 

 interval between the suooessive fellings on the same area and the forest to be divided 

 into ten coupes, or we may take as many times 1 '33 per cent, of the material as 

 there are coupes or years in the interval between the successive fellings. Now the 

 woi'd capital willbe far from being exactly and evenly distributed over the forest; 

 some of the compattments will be rich in material and some poor. Each year 

 there would, however, be exploited successively in each coupe in its turn 13 '3 per 

 cent, of the material on the ground, without ever exceeding this figure, but so 

 as to fell exactly 100,800 cubic feet of wood . If the 1 33 per cent, of the material 

 in a coupe exceeded the allotted total volume of 100,800 cubic feet, the aurpluB 

 would be left for the following year ; if less, the volume prescribed would be made 

 wood from the next coupe. In this manner what was felled in a compartment 

 would always bear a fixed ratio to what existed in that compartment; from the 

 rioh conipartment more would be taken, from the poor less ; while the outturn 

 could remain the same from year to year. 



Neat and exact as this volumetric method of calculating 

 the capability may appear in theory, there are several draw- 

 backs to its practical application, especially in Indian forests. 

 It is certainly superior to other methods, in that it secures 

 an absolutely equal outturn from year to year ; but this in 

 India is often a matter of comparatively small importance. 

 On the other hand, it not alone requires nice calculations 

 based on exact enumeration and measurement of the whole 

 standing crop — and this diflScult and expensive undertaking 

 must be repeated periodically — ^but it also necessitates fell- 

 ings entailing most careful supervision being made out- 

 side the coupe of the year. 



Altogether the method is in India inferior to that of 

 prescribing the capability by number of trees. Any mis- 

 take in estimating the production of the soil — always a 

 difficult calculation to make practically, however simple it 

 may appear in theory — would, under the volumetric method, 

 have a very injurious effect on the crop. This, as already 

 explained, cannot occur where the number of trees has 

 been fixed without limit as to size ; for if the possibility 

 were over-estimated, smaller trees, and consequently a less 

 volume of material than the calculated capability of the 

 forest, would be felled. 



It will be observed that the last two methods of deter- 

 mining the capability are based on the assumption that 

 all sizes of trees are saleable, and that the forests to which 

 the methods are applied are in the normal condition of 

 selection-worked crops ; that is to say, containing a complete 

 series of trees of all ages scattered irregularly over the 

 entire area. There are, however, comparatively few forests 

 in India in which these two conditions are found to co-exist. 

 For where the demand is good, the forests have for the most 



