310 



TIMBER 



SHEARING STRENGTH PARALLEL TO GRAIN AND COMPRESSION STRENGTH 

 AT RIGHT ANGLES TO GRAIN. 



The above results must not be taken as the strengths of 

 ordinary building timber, as these tests were made upon 

 small and carefully prepared pieces of wood, so as to get as 

 accurate and comparative results as possible, but it is safe 

 to assume that the drying of large pieces would give the 

 same proportional increase of strength. 



Shearing parallel to grain is a variable quantity and 

 cannot be depended upon to increase with dryness. 



Soaking timber in cold water does not diminish its 

 strength, whilst heating the water does so considerably, 

 and boiling the water causes a still greater diminution. 



Timber kiln dried and then resoaked is weaker than 

 timber of equal degree of moisture which has not been 

 dried, and does not fail like the original green beam, but 

 snaps at the bottom like that kiln dried, showing no com- 

 pression at the top ; kiln drying seems to increase per- 

 manently the brittleness of wood. A beam of green 



1 These tests were made with the load concentrated over a portion of 

 the area only, as in the case of a pillar resting on a horizontal sill. 



