34 THE COMMERCIAL HICKORIES. 



tains. This is particularly true in the case of hickory, in which free- 

 dom from knots and birdpecks, rapidity of growth, and width of 

 sapwood are so important, and vary so greatly under different con- 

 ditions. In an open stand, for instance, the trees run knottier and 

 there is less merchantable length, but the growth is more rapid and the 

 quality of the wood is better. In poor or exposed situations the 

 growth is slow and the wood is apt to be birdpecked. Lumbering, 

 moreover, differs greatly with the region and the purpose of cutting. 

 A great deal more of the tree is used, for instance, when it is cut for 

 handles than when it is cut for rims or shafts, and utilization is much 

 closer in the North and East than it is in the Mississippi Valley. 



Nevertheless, it is important, also, to know how much wood average 

 trees of different sizes contain and how much is merchantable. The 

 average tree can be used in estimating, and, when applied to a large 

 number of trees, gives fairly satisfactory results. It is especially 

 valuable in predicting future yields and can be used to foretell the 

 increase in volume of a 10 or 12 inch tree after it has made a certain 

 definite increase in diameter. 



While the merchantable volume of two hickory trees of the same 

 diameter and height may differ greatly, there is apt to be a greater 

 difference between a hickory and an oak or an ash of similar dimen- 

 sions. Each species has its own characteristic form and its own special 

 uses. It is therefore desirable to determine the contents of the aver- 

 age trees of each species. For this purpose a large number of trees 

 of different sizes were measured and, in the case of this hickory study, 

 not only were their merchantable volumes determined, but the amount 

 of firewood contained in the tops. The amount of heart, sap, and 

 bark in the used portions and the form of the entire stem were also 

 measured. 



Table 7 shows the total cubic contents including bark and limbs for 

 trees from 40 to 90 feet high and 5 to 18 inches in diameter, breast- 

 high. The average used volume is given in per cent of the total 

 volume. The table is based upon the measurements of 365 trees of 

 five different species of hickory cut in different parts of the country 

 for spokes, handles, rims, and shafts. In the merchantable portions, 

 the diameters were taken to tenths of inches ; in firewood, only 4-foot 

 sections, 2 inches and over at the small end, were considered, and the 

 diameters were measured in the middle of the sticks and rounded off 

 to half inches. The volumes are given in cubic feet, since this is the 

 most accurate unit of measure for timber of different classes. To 

 convert cubic feet into board feet it may be considered that 1 cubic 

 foot of merchantable material will saw from 5 to 7 board feet, or, on 

 an average, 6 board feet. To convert cubic feet into cords, it may 

 be assumed that 95 cubic feet of spoke or handle bolts is equal to 1 

 stacked cord ; and that 1 cord of firewood would contain from 60 to 

 90 cubic feet, depending on the size and straightness of the sticks; 



