192 FELLING AND 



volume by quarter-girth under bark is 100 cubic feet has 

 a true volume over bark of 153 cubic feet. 



For ordinary work by the square-of-quarter-girth method 

 it is not necessary to work out the figures, because prepared 

 tables, such as those compiled by Hoppus, are used. 



No tables are given in this book because useful cards, in 

 convenient form for the pocket, are obtainable for a few pence. 



If the tree is measured over bark it is usual to make an 

 allowance for this, but the amount varies in different parts of 

 the country. The most usual is half an inch for any quarter- 

 girth up to 12 inches, with an extra half-inch for every 

 additional six inches of quarter-girth for oak and other rough- 

 barked trees. Thus if a log has a quarter-girth of 10 inches 

 over bark, its quarter-girth under bark will be taken as 

 9! inches, while if it is 16 inches over bark it will be taken 

 as 15 inches under bark, and then the calculation of volume 

 will be made as before. This allowance is equal to a reduc- 

 tion of 1 6 per cent, on the total volume of wood and bark, 

 and in many cases is too much. In measuring beech in 

 Buckinghamshire no allowance is made. 



In actual practical work the measurement of felled timber 

 proceeds as follows : 



First the length of the log is taken, odd inches being 

 neglected, a five foot stick being the most convenient measuring 

 instrument. The length is noted in the woodman's notebook, 

 and the half-length is calculated and marked on the log. The 

 girth is taken at this point with a piece of whip-cord attached 

 to a bent wire by the aid of which it can be easily pushed 

 under the tree. The string is withdrawn and is twice folded 

 so that its length is then equal to J of the girth. It is held 

 up against a foot rule and its length is read off to the nearest 

 i inch below the actual length. Bark allowance is deducted 

 from this, and the quarter-girth under bark thus obtained is 

 entered in the notebook. Prepared tables are now used to 

 obtain the volume, the cubic contents being looked out under 



