THE WOOD 



229 



among many pieces, and the opening among many 

 joints. We also use panels in doors, and veneer in furni- 

 ture, and for the same reason bore 

 out columns, and build up columns 

 and posts of several pieces. 



Strength. Wood is very strong. 

 To crush a cube of dry wood one 

 inch each way, with the fibers on 

 end, requires about six to ten 

 thousand pounds pressure. It 

 requires only about one third to 

 one half as much if the piece is 

 soaked, or if it is green ; for sea- 

 soned timber is always stronger 

 than green timber of the same 

 kind. 



To pull it apart lengthwise, 

 wood requires about twice as much 

 power as to crush it endwise ; but 

 to pull it apart sidewise, as when 

 we pull out a mortise, requires 

 only about one tenth as much 

 force as to crush it endwise. 



Most conifers break without 

 much bending ; but elm, hickory, etc., are strong and yet 

 bend far before they break. We call them tough ivoods. 



Heavy woods are generally stronger than lighter woods. 



Fm. 86. Effects of 

 Shrinkage 



