WHY WOOD IS BEST 



BY ALFRED GASKILL, STATE FORESTER OF NEW JERSEY 



NO one thinks of building a battleship of stone, or 

 a bridge of copper, or a cabin of steel. The 

 qualities that determine the fitness of most structu- 

 ral materials are generally known ; the inherent quali- 

 ties of various woods, which make them valuable for 

 specific purposes, rarely are recognized. Wood sub- 

 stance, or cellulose, is much the same in all kinds of 

 wood, but a great diversity in the form and arrange- 



(2) with reduction of the moisture content. The first 

 requires a selection of the material more or less vigorous 

 according to intended use ; the second involves "season- 

 ing," by storage or by artificial means, until the wood 

 is "air dry." Fortunately it is now possible to know 

 the real qualities of most of our commercial woods and 

 to choose what is fit with only a guiding reference to 

 old customs and preferences. 



SPRUCE FENDER STOCK. OAK KEEL-AT THE PHILADELPHIA NAVY YARD 



ment of the elements produces a wide range of values. 

 Practically every species has a characteristic structure, 

 though it varies with the individual. 



But though wood in general must be recognized 

 as a material of great variability the constants in each 

 species give positive advantages for many purposes. 

 The truth of this depends upon the fact that fitness for 

 service increases (1) with uniformity of structure and 

 absence of defects (knots, cracks, crooked grain, etc.) ; 



For engineers there have been constructed elaborate 

 tables showing the resistances of all our principal woods 

 to bending loads, compression, tension, shearing, in- 

 dentation, etc. ; the non-technical reader will be better 

 satisfied with general statements. 



The user of wood is apt to define its qualities by means 

 of terms which mean quite definite things to him, but 

 which really are relative, or are capable of various in- 

 terpretations. For any important purpose it is advisable 



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