SCALING LENGTH OF LOGS FOR BOARD-FOOT CONTENTS 43 



they are applied at the middle point, or at the small end. Of the two 

 methods the small end gives the most consistent results in board measure, 

 since both the actual per cent utilized and the per cent of total con- 

 tents scaled decrease with diameter of log. But the decrease in scaled 

 contents is always at a lesser rate than that of actual sawed contents, 

 hence the tendency to over-scale small logs remains though the size of 

 the error is reduced. 



43. Taper as a Factor in Limiting the Scaling Length of Logs for 

 Board-foot Contents. Since board-foot contents of logs is equal to 

 cubic contents minus waste in sawing, the character and amount of this 

 waste determines the net scale of the log. This waste consists of saw- 

 dust, slabs and edgings. As lumber is commonly manufactured with 

 parallel edges, in even widths, the custom of sawing boards whose 

 length equals that of the log and rejecting all shorter pieces would cause 

 a waste not only of the slabs sawed from the cross section at the small 

 end but of the entire taper of the log, which would be discarded as 

 edgings and slabs. When board-foot rules were first brought into use 

 close utilization of short lengths and of wedge-shaped pieces was not 

 practiced, and this total waste actually occurred. Under these con- 

 ditions the correct point of diameter measurement was not the middle, 

 but the small end of the log. Owing to their early origin, the com- 

 mercial board-foot log rules now in use are nearly all based on measure- 

 ment at the latter point. 



This waste, as measured in cubic volume, increases rapidly with 

 increasing length of log. The shorter the logs cut from a given tree, 

 the less will be the apparent waste from taper. Long logs, the scaled 

 contents of which are based on cylinders measured at their small end, 

 would give an entirely different and much smaller scale than if the same 

 logs were cut instead into two or more shorter sections and sawed into 

 correspondingly shorter lumber. Instead of scaling one log of a given 

 top diameter sometimes extending the entire length of the bole, we would 

 then have to scale a series of shorter logs, each of which has a top diam- 

 eter larger than the preceding one by the amount of the taper between 

 the points measured. The sum of volumes of these short logs would 

 always exceed that of the single log measured at small end. These long 

 logs are usually cut into two or more sections at the mill. For these 

 reasons, logs, if their length exceeds a definite maximum are scaled 

 as the sum of two or more shorter logs, by taking caliper measurements 

 at arbitrary points of division; e.g., a 26-foot log scaled as two pieces 

 would be measured at its small end, and at a point 12 feet from the end, 

 thus scaling as a 12-foot and a 14-foot log. The scaling diameter of the 

 larger or butt section exceeds that of the top end by the amount of the 

 taper between the points measured. Each section is thus scaled as a 



