MEASUREMENT OF TIMBER 



203 



a half to one cubic foot. The inaccuracy thus introduced will 

 not be great. 



Should the true measure be required, then it is only necessary 

 to measure the sample tree by true measure instead of by the 

 square-of-quarter-girth. Again, if the timber is only saleable 

 down to 6 inches diameter at the thin end, the sample tree 

 should be measured down to this point. 



The accuracy of the method depends on finding sample trees 

 of average height and of exactly the same diameter at breast 

 height as the inch-class, and in careful measurement of their 

 volume. There are other methods of measuring whole woods 

 in which it is not so necessary to find sample trees of exact 

 size, but as these methods involve a good deal of mathematics 

 usually beyond the knowledge of the ordinary woodman, they 

 are not described here. They will be found fully explained in 

 Schlich's Manual of Forestry, Volume III. 



The following figures abstracted from the Forestry Com- 

 mission's bulletin No. 3 show the volumes in cubic feet 

 quarter-girth measure under bark which are found in well- 

 stocked British woods under average conditions. Unfortu- 

 nately no accurate figures, based on the measurement oi British 

 woods, are yet available for other species. 



