SHI AUIN. .-TKKNCTH. 



In It,, c \IL rimenK t.i deteimine I 111' -In i'l'tllllli'-l 



itideral>!- lillien!t\ w;i- tumid in prep iring Huitable t which 



WOllM li"t ;it the -am. time I"' liable to :i 1 ir_re 1 'I'm;; ucti'm. Blocks 



wiT'' prepared :i- shnwti h\ .-lviehe< A, I! :inil C ; but unle the ,,!dr- 

 wcre suffieientlj ^rnn.-ly elampi'd, a- in Fig. A, the specimens almost 

 invariably opened at M. under an .'fleet .-hiefly duo to bending. Tho 

 "laiupinu. a'.'ain. iiitrdiie"d i ecinipre-^inn. which rtodored it im'nmible 

 'lie true clie.inn-j -Ires-. 



All' : a iiuiiibev otVxp.'ii lit-, mure -atisfaetnry a'i'l reliable, re 



iied by prepariii'..' tCSt-piooea as shown by FIL'S. 10 and l>. 

 The bending action is by no means eliminated, and, generally speak- 

 ing, it a } raetieally impossible to frame limb'ir joints subjected to a 

 pure >l.ea" only. Tim shearing strengths, which are of importance, are 

 the r-!>tanees al"iiL' planes tM^gential and radial to the annular rings 

 An examination ")' the test-pieo s -lm\vs that tlic shears are invariably 

 .-ilonj; } H ]i!ani--. 



Thus it will be observed that in the tangential shears, the fibre, both 

 hard and -oft, is sheared radial y. in the radial shears tan^entially, and 

 invariably thnnuli the soft fibre. 



With t -st piece- of the form shown by Fig. 1), the shearing strengths 

 along the tin^'iitia'. and radial planes are obtained, while the compound 

 shearing -treiiirth. which nny be considered as the resultant of tho 

 t ingenti.-il and radial shears. i< obtained with the test-pieci;s of the form 

 shown by Fig. K. 



The following Tables give the results of experiments carried out 

 witl) test-pieces and holders of the form described : 



TABLE O7 TItK TANdENTIAL, RADIAL AND COMPOUND SHEARING 

 STRENGTHS OK l(Orr?l,AS FIR SPECIMENS CUT OUT OP THE SAMK 



BEAM. 



TABl.K Ob THE COMPOUND SHEA.RINH STRENGTHS OK DOUGLAS PIR 

 AND RED PINE SPECIMENS. 



105 



