712 JOURNAIv OF FORESTRY 



$4.73 in 1918. In several of the Northern States the average price 

 was practically twice this. Some slight discrepancy may have been 

 caused by different methods of securing figures and a more general 

 conception of a cord as meaning 128 cubic, feet, rather than a "short 

 cord." When one considers the decreased labor supply, with its re- 

 sultant high cost, it is not at all unlikely that, except for the wood- fuel 

 campaign there would have been an actual decrease in the production 

 of cordwood. Certain it is that the propaganda helped toward the 

 purchase of fuelwood, in spite of higher prices than ever before in the 

 history of this country. Had the war continued through the winter of 

 1918-19, there would undoubtedly have been a much greater consump- 

 tion of fuelwood, which would have been noted not so much on the 

 farms as in the villages and smaller cities, in which case this bulletin 

 would have been of value in correlating the wood- fuel campaigns which 

 were carried on throughout the several States. 



A Study of the frustum Form Factors of Hard Maple and Yelloiv 

 Birch. By B. A. Chandler. Bulletin 210, University of Vermont and 

 State Agricultural College, Burlington, Vt., March, 1918. Pp. 38, 

 plates 8. 



A form factor is the ratio, expressed decimally, between the volume 

 of a tree and the volume of a geometric solid of equal height and basal 

 area. There are several kinds of form factors, depending on how 

 much of the tree is included in making the volume calculations and at 

 what point the diameter of the tree is measured. In this country it is 

 generally understood that the diameter of the tree is measured at 

 breast-height, and that the volume of the stem, exclusive of the 

 branches, is used in comparison with the volume of a cylinder. This is 

 called the "breast-height stem form factor," or simply "the form 

 factor." If, however, the volume is understood to include not only 

 stem, but branches, it is called the tree form factor ; if only the mer- 

 chantable portion of the stem is included, then it is called the mer- 

 chantable form factor. In recent years other kinds of form factors 

 have been devised, as, for example, the so-called frustum form factor, 

 comparing the board-foot contents of trees, within certain merchant- 

 able limits, with the board-foot contents of ideal frustums of cones, in 

 which the taper is regular. 



If the time ever comes when the cubic foot becomes a common unit 

 of measure in this country, it is quite probable that form factors will 

 be more generally used here. For the present, the use of form factors 

 will doubtless be confined rather closely to theoretical investigations. 



