VOLUME OF BRANCH AND ROOT WOOD. 33 



In Britain and in India, the sectional area in the middle is 

 calculated by the method of the quarter girth, that is to say, 

 by the formula 



In comparing this with the real sectional area = '0796 X<f, 

 it is found that the quarter girth method gives only 78J% of 

 the true volume, omitting 21 J per cent. The method is based 

 upon the assumption that this amount represents the waste 

 incurred in squaring the timber. Quantities calculated by the 

 exact method can be converted into the quantities corresponding 

 to the other, by deducting 21 J per cent, of the volume. 



2. Volume of Branch and Root Wood. 



In some cases special pieces of branch and root wood are of 

 a sufficiently regular shape to measure and calculate their 

 volume separately in the manner given above. As a general 

 rule, however, such wood requires a different treatment. Its 

 volume is ascertained by shaping it according to custom, and 

 stacking it in a space of regular geometrical form. The volume 

 of this space is ascertained, as well as the quantity of solid 

 wood of a particular description which can be stacked in it. 



Taking, for instance, a space of 100 cubic feet, the quantity 

 of solid wood which can be stacked in it is ascertained 

 according to whether the material consists of split wood, 

 branch wood, fagots or root wood. This can be done by 

 measuring each piece separately, an operation of considerable 

 difficulty, and one which takes much time. A more expeditious 

 way is to submerge the material in a xylometer and ascer- 

 tain the volume by measuring the quantity of the displaced 

 water. From the data thus obtained, average coefficients are 

 calculated. 



It is evident that different descriptions of wood give 

 different coefficients. The solid contents of stacked wood 

 depend on many things, amongst which may be mentioned : 



VOL. III. D 



