MEASUREMENTS OF TIMBER 



actual amount of timber exceeding 3 inches in diameter 

 but less than 6 inches in quarter girth varies with the 

 species and age of the trees. In the case of young poles, 

 there will be from 3 to 6 cubic feet (quarter girth). But if 

 the trees are old, this amount will be reduced in the 

 case of coniferous trees to about 2 to 4 cubic feet 

 (quarter girth) ; whereas in the case of broad-leaved 

 trees, which form large crowns, the amount will be from 

 3 to 5 cubic feet, and often more. 1 



String measurement has been adopted, as by far 

 the greater amount of felled timber is still measured, 

 and probably always will be measured, by this method. 



However, it is necessary to remember that "in the 

 fold of the string " about half an inch is lost on every 

 quarter girth as compared with measurements taken 

 with a tape. 



Now, in the case of small-girthed trees, this loss of 

 half an inch makes a vast difference in the contents per 

 acre of any crop of trees. 



For instance, a pole might be 40 feet long and 5 

 inches quarter girth by tape measurement, or only 5 

 inches quarter girth by string measurement. In the 



1 In the case of trees grown as standards over coppice, the amount 

 is usually very considerable, and will often be from 5 to 9 cubic feet. 



former case the contents would be 8 cubic feet 5 inches, 

 whereas, in the latter case the contents would only be 6 

 cubic feet 11 inches, thus showing a difference of nearly 

 18 per cent. In larger girthed trees the relative differ- 

 ence is not so great. For instance 



in trees averaging 9 or 9 inches quarter girth, the 

 difference would be about 10 per cent. ; 



in trees averaging 12 inches quarter girth, about 8 

 per cent. ; 



in trees averaging 19 inches quarter girth, about 5 



per cent. ; 

 and so on. 



However, these are very considerable differences, 

 and they afford one of the many reasons why Con- 

 tinental yield tables, which are based upon mathe- 

 matically accurate calculations, are quite inapplicable 

 for practical use in this country. 1 



There are many who advocate the abandonment of 

 string measurement, and who would substitute always 

 the use of the tape. However, ancient customs are 

 wont to " die hard," and it is necessary to remember 

 that it is often most difficult to pass a tape under 

 fallen timber, whereas such difficulties are compara- 



also p. 6. 



