THE GENERA,!. WORKING SCHEME. 149 



(II) That of the Improvement Cuttings, that is, of Accessory 

 Produce. 



In a regular Working Circle of high forest, the principal 

 produce would be furnished exclusively by the trees felled in the 

 Block assigned to the current Period ; but, as a rule, the other 

 Blocks also contain here and there mature trees either solitary or 

 forming leaf-canopy , which it would be expedient or necessary to 

 exploit as an exceptional measure during that P^.riod. Ussually in 

 estimating the annual yield of principal produce, such trees are 

 classed, without any qualification, amongst those of the Block of 

 the current Period ; only in the Organisation Project their relative 

 number and importance should be clearly indicated and the 

 compartments that contain them mentioned. 



The determination of the quantity of principal produce 'offers 

 no difficulty. It is obtained by enumerating the standing trees 

 grouped into classes according to species and diameter, and multi- 

 plying the number of the trees in each class by the previously 

 ascertained contents of a type tree, selected from amongst the 

 standing material as presenting the average of that class-t^ 



But the total quantity of produce ultimately removed during 



the Period necessary includes, besides the actual contents of the 



Standing trees, also their future inereiiietit up to the time they are 



felled. To determine the amount of this increment it may be 



observed that the quantity brought under the axe is the same every 



■ — — ' ' ■" — — '■ — '■ "' r '""' — 



(1) It is unnecessary to obtain actual contents witli rigid accuracy, but 

 it is indispensable, ia taking the measurements, to adopt a uniform practical 

 System. It is the only way of arriving at results that admit of being compared 

 one with anotlier — an essential condition for the location of the coupes, and 

 useful afterwards for the verification of the yield. If, for instauco, in ths 

 valuation it was assumed after eipSriment that trees measuring 16" ia girth 

 at the height of a man contain on an average 46 cubic feet each, thfta ift 

 locating the fellings also it would be necessary to assign the same volume to 

 trees of 16* girth. Whether the average contents assumed be exact or simply 

 approximate, the quantity eiploited woilld always be an invariable proportional 

 CI the quantity obtained by valuation. Thus 1000 cubic feet of felled produce 

 would actually represent 1000 cubic feet of the estimated yield. It would be 

 otherwise if any other procedure were adopted, that was not based on the 

 measurfement of exactly measurable elements. Hence it is necessary in 

 calculating the yield by volume to avoid estimating the quantity of standing 

 material with the eye, or by means of type areas, or with the aid bf any other 

 such system. And for the same reason the basis of all valuations must be 

 solely and invariably the measurement of diameter, since that of height always 

 involves some amount of individual appreciation, 



