DOUGLAS FIE, WHITE PINE AND EED PINE. 



17 



These experiments on the shearing strength show a marked increase of strength with 

 the density of the annular rings, or rather with the amount of fall growth as compared with 

 the spring growth. 



Table of Shearing Strength of Douglas Fir Specimens cut out of same Beam. 



Compressive Strength. 



Numerous experiments have lieen made in the laboratory to determine the ultimate 

 compressive strength of the various timbers, but a large number of experiments are yet 

 required before any general law can be enunciated. It was found, as might have been 

 expected, that there is a gradual diminution of compressive strength with the increase of 

 the ratio of length to the least transverse dimensions. It was also found that the strength 

 is largely governed by the part of the stick from which the block is cut, being, as might 

 have been supposed, stronger where the density of the ring growth is greatest. The general 

 average results obtained were as follows : 



Douglas Fir. 



' The results Nos. 13 and 14 were very low, and were due to the fact that the holders did not fit closely around 

 the spindle, so that a large bending action was introduced. 



Sec. Iir., 1894. 3. 



