INTRODUCTION. 



Wood is now, has ever been, and will continue to be, the most widely 

 useful material of construction. It has been at the base of all material 

 civilization. In spite of all the substitutes for it in the shape of metal, 

 stone, and other materials, the consumption of wood in civilized coun- 

 tries has never decreased; nay, applications in new directions have 

 increased its use beyond the saving effected by the substitutes. Thus, 

 in England, the per capita consumption has increased in the last fifty 

 years more than double, a fact which is especially notable, as the bulk 

 of the timber used there must be imported, while iron and coal are 

 plentiful in Great Britain. 



In the United States we can only estimate from the partial data fur- 

 nished by census returns. By these we find the per capita consumption 

 to have increased for every decade since 1800 at the rate of from 20 to 

 25 per cent. 



Although wood has been in use so long and so universally, there 

 still exists a remarkable lack of knowledge regarding its nature in 

 detail, not only among laymen, but among those who might be expected 

 to know its properties. As a consequence, the practice is often faulty 

 and wasteful in the manner of its use. Experience has been almost 

 the only teacher, and notions— sometimes right, sometimes wrong — 

 rather than well-substantiated facts lead the wood consumer. Iron, 

 steel, and other metals are much better known in regard to their prop- 

 erties than wood. The reason for this imperfect knowledge lies in 

 the fact that wood is not a homogeneous material, like the metals, but 

 a complicated structure, and so variable that one stick will behave very 

 differently from another stick, although cut from the same tree. Not 

 only does the wood of one species differ from that of another, but the 

 butt cut differs from the top log; theheartwood from the sap wood; the 

 wood of the quickly grown sapling of the abandoned field from that of 

 the slowly grown old monarch of the forest. Even the manner in which 

 the tree was sawed and the condition in which the wood was cut and 

 kept influence its behavior and quality. It is, therefore, extremely 

 difficult to study the material for the purpose of establishing general 

 laws, and it becomes necessary to make a specific inspection of the 

 individual stick which is to be applied to a certain purpose. The 

 selection, not only of the most suitable kinds, but of each stick, for the 



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