CHAPTER I. 



THE MEASUREMENT OP LOGS, STANDING TREES, AND WHOLE CROPS 

 OP TIMBER, AND OP THEIR INCREMENT OR RATE OF 

 GROWTH. 



I. Measurement of the Cubic Contents of Logs, Trees, and 

 Timber-crops. 



1. Logs. The British method is square - of - quarter - girth 

 measurement, the mean girth of the log being measured half- 

 way between the two ends, then divided by 4, and squared, 

 and multiplied by the length of the log in feet. And if 

 the girth be taken in inches, the product of the quarter-girth 

 squared multiplied by the length in feet has to be divided 

 by 144 to obtain the result in cubic feet. In practice, tables 

 of cubic contents are used for ready reckoning, varying by 

 inches in mean girth, and by feet in length (see Tables in 

 Appendix I., pp. 147 to 150). But the true cubic contents of 

 any log is equal to length x superficies of middle section length 

 x (TT diameter 2 -f- 4) - length x (diameter** x 0*785), which gives 

 a result just 21 J per cent more than that obtained from the 

 square-of-quarter-girth measurement, length x (mean girth -^ 4) 2 . 

 This shortage of 21 J per cent, was originally intended to cover 

 wastage in sawing and conversion. 



For example, say a log measures 20 ft. long and 8 ft. in mean girth. 

 Its true contend? are 20 x(8 2 -f 4 IT) = (1280 -M2 '566) = 101 '8 cubic ft.; while 

 its square-of-quarter-girth contents are 20 x (8-f 4) 2 =80 cubic ft. or, if 



