STRENGTH AND TESTING OF TIMBER 319 



of safety : For timber in shearing, and compression across 

 grain, 4 ; for columns under 15 diameters high and for end 

 bearing, 5 ; for extreme fibre stress in transverse rupture, 

 6 ; and in tension with and across the grain, 10. 



As there is such great variety in the results arrived at 

 as to the strengths of timber tested by different people, only 

 those tests which have been made upon a large number of 

 samples of the same wood reduced to a standard degree of 

 moisture have been given in this work, and the author has 

 only gone so far into the question of testing timber as to 

 show the inquirer what errors to avoid and lead him by 

 references to more detailed information. 



Sufficiently accurate statistics are not yet available for 

 dealing in great detail with tests on timber. 



