VKBIFICATION' OF THK ANNUAL YIELD. 159 



the beginning of the Period, without checking its figure in the 

 meanwhile. This check is what we have called the VERIFICATION 

 OF THE Annual Yield. 



The check in question consists in ascertaining, at some time 

 during the currenc)- of the Period, the quantity of standing material 

 still unexploited, and then dividing that quantity by the number 

 of years in the unexpired portion of the Period, exactly in the same 

 manner as was done at its beginning. It is obviously necessary to 

 employ the same procedure and the same tables as before, otherwise 

 the results obtained on each separate occasion could not be com- 

 pared together. Before dividing the quantity given by the valua- 

 tion survey, it is necessary to deduct from it the still available 

 portion of the Reserve Fund that may have been deduced from the 

 annual yield in the first instance. This pro'^edure is indispensable 

 in the interests of the future. The whole of the unexploited stock, 

 reserved in order to provide against extraordinary requirements, 

 ought to continue to be available up to the very end of the Period, 

 and this for the very same reasons which originally justified the 

 establishment of the Reserve Fund. As regards the actual increment 

 by which the standing stock may have increased since the begin- 

 ning of the Period, it necessarily forms an integral part of the 

 contents found by the valuation surveJ^ But in revenge the valu- 

 ation survey has nothing to do with the trees left standing after the 

 Final Fellings; so that those trees in no way afifect the calculation 

 ot the annual yield in the second instance. 



If, owing to unforeseen circumstances, any considerable exploita- 

 tions have had to be made in the immediately following Block, it 

 might l)e expedient to effect a compe,nsation by increasing the 

 stock to be reserved during the rest of tlie Period. Under any 

 circumstances, the Verification of the Annual Yield must alter the 

 figure originally estimated, but it cannot modify the General 

 Working Scheme, since the calculation of the annual yield is 

 entirely independent of the formation of the Blocks- It is necessary 

 to verify the annual yield of principal produce at least once during 

 the course of each Period, so as to avoid all risk of having an ac- 

 cumulation of errors crowded into the last few years of the Period. 



WHien the fellings that are regulated by area, notably so the 

 Thinnings, have been arranged at the beginning of the Period for 



