116 



Forestry Quarterly 



O. L. S. 



Woodcraft, August, 1914. 



During the past three years the Forest 



Relation of Service has made 90,000 tests on small 



Strength to clear specimens of American woods. These, 



Specific Gravity together with other comparable tests by the 



Service, bring the total number to about 



130,000, and comprise 110 species. 



"From the tests of green and air-dry material approximately 

 fifty different average values are derived for each species. Many 

 of these are closely related. The relation of each property to 

 specific gravity has been considered in order to compare one species 

 with another, to determine the relation between the different 

 properties, and wherein each species is exceptional. In general, 

 not only are the denser pieces of a given species the stronger, but 

 the relation of specific gravity or dry weight to strength gives an 

 indication of what strength might be expected from pieces of an 

 entirely different species. The average values of the different 



