The Mechanica Properties of Wood

Abstract

TO those unfamiliar with the composition and construction of wood it comes as a matter of surprise that the “hardness,” calorific value, also, to some extent, the strength and certain other mechanical qualities, are proportional to the apparent specific gravity. Yet the unexpectedness of these relations vanishes when it is realised that a piece of completely dried wood contains, in addition to air and insignificant amounts of ovarious substances, wood-substance the specific gravity of which is approximately (or truly?) the same in all kinds of woods. Two pieces of dry wood of the same volume thus differ in weight nearly solely because one contains more wood-substance than the other. Wood is not a material, but is a heterogeneous and varied structure, and its particular mechanical properties are dependent not merely on the amount of wood-substance contained in its unit of volume, but also on the manner in which that substance is excavated in the form of strong fibres, weak vessels, and so forth. The arrangement, form, and numbers of these constituents vary widely in different kinds of timbers, with the result that these display corresponding differences in their mechanical properties.

The Mechanical Properties of Wood.

By Prof. S. J. Record. Pp. vi + 165. New York: J. Wiley and Sons, Inc.; London: Chapman and Hall, Ltd., 1914.) Price 7s. 6d. net.