136 STACKED OR CORD MEASURE 



The board-foot contents of a stacked cord depends first on the solid cubic con- 

 tents of the cord rather than its stacked measure, and second, on the diameter 

 of the sticks which it contains (§ 54). Since soUd contents also depends on diam- 

 eter of stick, the ratio of board feet to stacked contents increases with diameter 

 from both sources, or much faster for stacked than for cubic volume. 



The diameter of the average stick is the determining factor in this ratio. The 

 ratio itself will thus vary over a wide range depending on the class of wood handled. 

 Crook and other irregularities of form have the same double effect as diameter, 

 in reducing first the soUd contents, and next, the board-foot contents per cubic 

 foot of wood. The latter ratio can be determined for straight sticks by Table III 

 (§ 41), Tiemann log rule, based on middle diameters, outside bark. For crooked 

 sticks, a further reduction in ratio is required. 



To obtain the true ratio for a given cord of straight wood, it is necessary to 

 determine first, the converting factor for sohd cubic contents, and second, the 

 average diameter of the sticks, at middle point outside bark. By use of Table III 

 the converting factor from cubic to board feet is found for logs or bolts of this 

 average size, and this multiplied by solid cubic contents gives contents of the 

 stacked cord in board feet. 



But commercial log rules are based on diameter at small end and do not usually 

 give actual sawed contents. For such rules the ratio can be approximated directly 

 by determining the average diameter and number of sticks in a cord, and scaling 

 their contents with a log rule. 



The ratio for actual board-foot contents of cordwood diminishes to zero for 

 sticks averaging from 3 to 4 inches in diameter, which is a common size for cord- 

 wood. If so determined, the converting factor is not an indication of the real 

 volume or utility of the contents of a cord of wood. For a given species and class 

 of cordwood an arbitrary converting factor can be obtained, based first on the 

 per cent of solid cubic contents of a cord of sticks of average diameter and second, 

 on an average or fair ratio between board feet and cubic feet, and not on the ratio 

 for the actual small or irregular sizes. For instance, western juniper cordwood 

 gives about 60 cubic feet per cord. Adopting a fairly low ratio of 46 per cent or 

 5.55 board feet per cubic foot of total solid contents, the board-foot converting factor 

 is 60 times 5.55 or 333 board feet per cord, or 8 cords per 1000 board feet. For 

 white pine, 100 cubic feet per cord, with nearly the same ratio, 5.5 board feet per 

 cubic foot, gives 550 board feet per cord. The ratio of 500 board feet per cord 

 adopted by the U. S. Forest Service for pulpwood gives 5.55 board feet per cubic 

 foot for wood yielding 90 cubic feet per cord, which is a fair average for well-shaped 

 sticks. 



It would appear then that the factor 5.55 has some merits as a universal con- 

 verting factor and that the variation of board-foot converting factors for entire 

 cords should be based on the difference in cubic contents of the cord rather than by 

 the adoption of variable ratios between board feet and cubic feet. This practice 

 is sound. The factor 5.55 corresponds to the actual sawed contents of a log 

 between 7 and 8 inches in diameter at middle of stick inside bark. The basis 

 of this ratio is comparison between total cubic contents including taper, and actual 

 sawed contents. Commercial log rules deal with reduced values for both cubic and 

 sawed output, using the contents of the small cylinder for the one, and neglecting 

 over-run in the other. These two reductions may not be of equal weight, but tend 

 to give approximately equal ratios to those stated. 



If the average diameter of logs exceed 7^ inches at middle, inside bark, the actual 

 ratio is correspondingly larger. Only in this way can ratios as high as 575 board 



