90 THE MANAGEMENT OF WOODLANDS. 



the girth be measured in inches, 20 x (96 -f I) 2 -f 144 = 80 cubic ft.; and 

 the proportion of shortage is 101'8 : 80 ::100 :78'5, or = 21| per cent of 

 the true cubic contents. 



Quarter-girth measurement is also customary in British India ; but 

 in Canada, Australia, and New Zealand the American B.M. system of 

 board-measurement is used', where the cubic contents are estimated on 

 the number of superficial feet they will yield as boards 12 in. broad and 

 1 in. thick. 



In all estimates and transactions concerning lumber, felled or standing, 

 the method adopted in the United States is board measurement, or B.M., 

 the board foot unit being generally defined as a board 1 ft. long, 1 ft. wide, 

 and 1 in. thick ; but in actual trade practice it is 144 cubic in. (or ^ of a 

 cubic foot) of manufactured lumber in any form. In buying logs by this 

 B.M. measure, one must first estimate what each log will yield in 1-in. 

 boards. For this purpose timber-tables are used, which give in board- 

 feet the contents of logs of various lengths and diameters. Under this 

 system the buyer pays only for the saleable timber in each log when 

 converted, while the inevitable wastage in slabs and sawdust is not 

 included. This is merely a different way of arriving at the object aimed 

 at in the customary British "square-of- quarter-girth " measurement, which 

 estimates the contents of a log to be 21^ per cent below its true cubic 

 contents ; for 1000 board feet of wood (which are equal to 83| cubic ft.) 

 are produced from a log containing about 110 cubic ft. in actual contents, 

 thus allowing for a wastage of nearly 24 per cent. 



But besides the reduction thus everywhere made in Britain 

 by square- of-quarter-girth measurement, a bark-allowance is also 

 customary, varying according to local usage up to T ^ of the mean 

 girth, or 1 inch per foot ; and this is equal to a further reduction 

 of 16 per cent on the contents of the log as shown by square- 

 of-quarter-girth measurement, and to 20 per cent of the true 

 cubic contents. But for thin-barked trees, like Spruce, Silver 

 Fir, and Beech, this would often be an excessive allowance. 



In the above example of a log 20 ft. long by 8 ft. mean girth, the full 

 bark-allowance would be 8 in., and the cubic contents below baric would 

 be 20 x (88 -~ 4) 2 -f 144 = 67-22 cubic ft., or a further proportionate reduction 

 on the customary measurement of 80 : 67-22 :: 100 :84, or = 16 per cent 

 of the square-of -quarter-girth contents ; and 78^ : 100 = 16 : 20, or 20 per 

 cent of the true cubic contents. Thus the British landowner selling 

 100 cubic ft. of standing .timber may only get paid for 100 -(21^ + 20) 



