26 ECONOMICS OF FORESTRY. 



eight times as great as an iron bar of the same 

 length and weight. Moreover, the wooden beam 

 will endure greater distortion than the metals with- 

 out receiving a " set " or permanent injury. 



The ease with which it can be shaped and keeps 

 its shape, the softness and yet unchangeableness, its 

 non-conductivity of heat, of electricity, which makes 

 its use more comfortable than that of metals, in 

 addition, its light specific weight and many other 

 qualities, recommend it for many purposes in pref- 

 erence to other materials. 



But above all things its cheapness recommends it, 

 we are paying now, leaving out fancy woods, at 

 the most 60 cents per cubic foot for the best wood, 

 shaped, as against $5 to $10 per cubic foot for iron 

 in sheets or bars. Moreover, it is the only material 

 of construction which we can produce and repro- 

 duce at will, while we know that most other mate- 

 rials now in use must be sooner or later exhausted. 



Other materials have displaced wood in some 

 uses, but other uses have arisen for wood, and often 

 the substitutes have again been displaced by wood, 

 when its superiority or peculiar qualities have been 

 more fully recognized. Even in such nicely bal- 

 anced structures as the bicycle, for which metal 

 seemed the only proper material, wood has proved 

 itself superior, at least in certain parts. 



A remarkable instance of this return to the use 

 of wood instead of metal is that for factory and 

 warehouse construction in order to reduce danger 



