HARDWOOD RECORD 



33 



who likewise has extensive manufacturing interests. ' ' And I do 

 not regard it as temporary, but rather as the development of a per 

 manent condition. Consumers are using more low-grade stock, while 

 there is less being offered by the smaller producers than ever before. 

 While all kinds of hardwoods have advanced in price, the increased 

 values of low-grades are noteworthy because of the relatively larger 



production of this kind of lumber. I have noticed that lumber prices 

 seldom decline gre<atly, in spite of temporary fluctuations, and there- 

 fore I am inclined to believe that the present high prices being paid 

 for common lumber are likely to continue, along with a steady demand, 

 particularly as there is no possible chance for any excess of supply 

 in the near future. 



' ^eo'x;!}i>a^^^:TOC>iOJa w i;y.'iv5iy^ui t ^iWil^^^^ 



An Analysis of Wood Values 



To those who handle lumber as a business without having made 

 a study of its utilization, it is often not clear just what are the 

 properties which, directly or indirectly, lead the artisan to prefer 

 a particular kind of wood for a special purpose. Not infrequently 

 a lumberman handling certain woods will prevail upon a manu- 

 facturing consumer to try out a wood as a substitute for the 

 species which he has been accustomed to use, and often with 

 disastrous results to both parties. Woods differ much in both 

 physical and mechanical properties; one may be entirely adapted 

 for a specific purpose and yet another and almost similar species 

 may be totally unfit for the same use. A better knowledge of the 

 properties of woods would be of material assistance to the manu- 

 facturer, the distributor and the consumer. The properties of 

 wood which make them desirable or undesirable, as the case may 

 be, for a particular use may be grouped as follows: 



1 — Mechanical properties, such as strength, toughness, stiffness, 

 etc. 



2 — Physical, such as weight, length and character of fiber, and 

 behavior during and after seasoning. 



3 — Chemical, such as color, durability, and value as fuel. 



-t — Structural, such as texture, beauty of pattern, etc. 



5 — Biological, such as form, size, and abundance. 



Of the several groups, the mechanical properties naturally take 

 precedence, and of these, toughness and stiffness are unquestion- 

 ably the most important, so that even the most general classifica- 

 tion of woods into "hardwoods" and "not hardwoods" (for this 

 latter class, though by imjilication the conifers, has so far no name 

 in this country) depends not at all on hardness as the word might 

 suggest, but on toughness, the tough woods being the hardwoods, 

 the others the conifers. Since toughness is a combination of 

 strength in several directions, the various forms of strength should 

 first be considered separately. 



When in use, wood usually breaks in bending, as in the case of 

 an axe or fork handle, or else in shearing or splitting, as seen in 

 planks and boards, whether on the sidewalk or in the wagon body. 

 Wood fails much more rarely in compression, though much exposed 

 to this form of strain, and still less frequently in tension, since 

 in this direction its resistance is enormous, and can, in ordinary 

 articles, ne\er be brought to fair trial. 



Fundamentally, all strength of wood depends upon four different 

 forms of resistance, namely, the resistance to tension, or length- 

 wise separation of the fiber; resistance to compression lengthwise; 

 resistance to compression sidewise, or to collapse of fiber, and 

 lateral adhesion of the fibers. Where a stick of wood is tested, 

 none of these forms of resistance can be isolated and tested sepa- 

 rately, and in every kind of failure two or more are represented. 



Since the strength of the fibers in adhesion is very much less 

 than in tension and compression, adhesion enters into nearly every 

 test as an important factor. 



Thus, if a piece of wood consisting of several fibers is testeil in 

 tension, the fibers would probably not break at all, but be merely 

 pulled out, the failure, as far as they are concerned, being due 

 to lack of adhesion and not to a lack of tensile strength. Every 

 tension test presents numerous cases of this kind, the broken fibers 

 presenting the even fracture, but being splintered and drawn out, 

 especially if the wood is good. 



In the same way when a piece of wood is compressed ifngthwise, 



some fibers badly situated with regard to the action of the load 

 collapse or else crush into their neighbors, and immediately a 

 breach develops, into which fiber after fiber falls, the breach 

 spreading from this point; and the whole mass of fibers, now no 

 longer adhering in this plane, behave as a great number of separate 

 fine strands — they "buckle," and the piece fails. 



Bending is a compound test of compression on the upper (con- 

 cave) side of the beam and tension on the lower (convex), ami 

 numerically stands between these two; that is to say, if a stick 

 breaks in bending, whether it break first on the upper side (in 

 compression) or on the lower side (in tension), the bending 

 strength, as commonly stated, is neither equal to the compression 

 strength nor to the tension strength, but lies between the two. 

 Here, as in the cases cited, adhesion forms one of the factors, since 

 at failure, part of the rupture consists in a separation of fibers. 



Shearing along the fiber is simply a test in adhesion, where thu 

 force acts in line parallel to the fiber, and the values in shearing 

 wherever tested agree with those of tests in "transverse tension," 

 as the test of adhesion may be termed. 



In splitting or cleaving, the case is, like shearing, almost entirely 

 one of transverse tension; with this difference, however, that the 

 force is applied to a small area and acts on a lever (the side of the 

 cleft) ; it acts, therefore, the more effectively the longer the cleft 

 and the stiffer the wood. From what has preceded, it is evident 

 that the adhesion of the fibers, or better, the resistance to trans- 

 verse tension, if of great importance. Examining the structure 

 it is quite apparent that this resistance is greatly influenced by 

 the shape and relative position of the fibers. In hardwoods the 

 cells do not arrange themselves in rows; hence, there are no 

 natural cleavage planes (except at the pith rays). A knife passing 

 along a line does not merely separate two layers of fibers; it has 

 to cut through the cells themselves; while if passing through con- 

 iferous wood it finds a natural plane of contact between two 

 sheets of fibers, and thus has easy work. Moreover, the course 

 of the fibers in hardwoods is rarely straight, the fibers are generally 

 in oblique positions (best illustrated in elm), they "interlace," 

 and if a piece of wood is split the surface is fuzzy with the myriads 

 of fibers which were not merely separated, but were torn in tension, 

 the very way in which they offer the greatest resistance. For these 

 reasons hardwoods have generally a much greater strength in 

 transverse tension than the conifers. Thus, oak 'excels haril pine 

 nearly as two to one. Where this greater resistance to transverse 

 tension is accompanied by a greater flexibility, by more "give," 

 as is nearly always the case with hardwoods, the wooil becomes 

 tough; a blow may indent, but does not shatter. 



This toughness is a combination of relatively great strength in 

 transverse and longitudinal tension together with a fair amount 

 of flexibility or capacity to endure distortion. That toughness 

 varies widely is well known, as is shown in the elm, which excels 

 in toughness, and in the yellow poplar, which |)ossesses but little. 

 Naturally the hardwoods exhibit it to a much greater degree than 

 the conifers. Even a jioplar board will bear far longer the constant 

 jar and jolt and wrench which it must endure as a part of a wagon 

 box than a very strong piece of pine or other conifer, and great 

 toughness, such as exists in good hickory, is not possessed by any 

 known coniferous wood. 



Hardness in wood means the resistance which any surface, but 



