— 47 — 



the test. The piece was weighed and the weight so obtained was taken 

 as that at the moment of testing; subsequently the same piece was put 

 into drying oven and was heated at 100°-120°C. for 6 hours till no 

 decrease of weight was observable and this was taken as the net weight 

 of the piece at the moment of perfect desiccation. Deducting the latter 

 from the former, the difference obtained is the moisture content of 

 wood. 



6. Determination of the Quality of Timber for Building. 



Durability of strength are of course desired in wood to be used for 

 building purposes. 



The toughness of wood as advocated by Tetmajer should never be 

 overlooked. Thus, the area included between the stress-strain curve and 

 initial line (which is zero) will readily denote the amount of work done 

 upon the beam and will serve as a good measure of the quality of wood. 

 Brittle wood shows the least work done while tough wood shows the most. 

 Since, however, a large deflection is so undesirable in building timber the 

 amount of work alone does not serve as a good criterion in determining 

 the quality of timber. The author was consequently led to accept instead 

 of the amount of the work done, the quotient obtained by dividing the same 

 by the deflection at the moment of rupture. Such a quotient is used in 

 comparing the quality of woods. 



V. Results of the Experiment 



Results of the above experiments has been entered in Table I-IV, the 

 main points in which are as follows: — 



(1) The rupture of wood generally begins with the strained tissues 

 of the wood tested, in other words, the tissues in the under part of the 

 beam. 



(2) The nature of the rupture differs according to the amount of 

 moisture contained in the wood. In general, wet wood shows instead of 

 perfect rupture a shearing of the strained surface under side of the beam. 

 Wet wood shows a greater deflection than dried wood. 



(3) Dried wood is stronger than wet. 



