126 STACKED OR CORD MEASURE 



contents of a cord of wood with bark, for the same species and sizes of 

 sticks. The shrinkage in stacked contents after peehng exceeds that 

 caused by loss of Ijark because of this closer piling. Bark is a waste 

 product for pulpwood or excelsior and purchasers prefer to buy peeled 

 wood. 



The thinner the bark on a tree the smoother it is apt to be. Species 

 with smooth bark yield appreciably more solid contents in stacks than 

 thick-barked trees, because in the latter case the bark is usually irregular 

 and fissured. Hence conifers such as spruce and balsam, and hard- 

 woods like white birch and poplar give the highest contents per cord, 

 while hardwoods such as oak and maple yield considerably less per 

 cord than conifers. 



The same difference holds for branch wood as contrasted with l^ody 

 wood, open-grown and limby trees compared with those grown free 

 from branches in close stands, and split wood with twisted grain com- 

 pared to straight grain. 



While the splitting of sticks decreases the solid contents, by increasing 

 the irregularities of surface and the effect of crook through reduced 

 diameters, split corclwood is usually cut from much larger bolts than 

 round sticks, and hence a cord of split wood may contain a greater 

 solid content than one of round sticks, especially if the round pieces 

 are below 3 inches and cut from limbs. 



105. Effect of Dimensions of Stick on Solid Contents. The effect 

 of a given amount or rate of crook, or of given irregularities of surface, 

 in diminishing the solid contents of a stack, increases with increased 

 length of stick, but this effect is more nearly proportional to the square 

 of the length than to the length. Hence the longer the sticks in a 

 stacked cord, the less its net cubic contents, other factors being equal. 



This explains the shrinkage in cubic volume when 4-foot wood is 

 cut into shorter lengths and restacked. In sticks longer than 6 feet 

 this becomes a serious factor and pulpwood from fairly straight logs 

 when sold in from 8- to 12-foot lengths gives about 12 per cent less cubic 

 contents than for 4-foot bolts (Table XXI, p. 130). 



Conversely, the cubic volume of sticks increases as their cross- 

 sectional area, which is as the square of the diameter, while the effect 

 of both crook and surface irregularities increases in porportion to the 

 'surface of the stick, which is directly in proportion to diameter and 

 consequently less than cross-sectional area or volume. A crook of 

 2 inches in a stick with 3-inch diameter has twice the effect that a 

 2-inch crook would have on a 6-inch stick. Due to these relations, the 

 solid contents of a cord of wood always increases with the increased 

 average diameter of the sticks, but diminishes with increased 

 length. 



