HOW FAILURE UNDER STRESS OCCURS IN TIMBER. A27 
of length investigated and for rectangular sections, the maximum fracture stress per 
square inch, p, may be represented by p= Se i instead of the more common Rankine- 
Ist OF 
Gordon formula, p = Se ;, where 
a =constant depending on material and method of holding test piece. 
/= length of test piece. 
k = least dimension of cross-section. 
jf, =maximum crushing stress per square inch determined from a test piece when /=k. 
a= ‘015 for Boxwood with square ends. 
025 99 Oak be) 99 ” 
02 bb) Ash a: bP) ” 
Fig. 37 shows the results of the tests plotted in this way. 
