292 



TESTIXU OF STRUTS. 



the deflection noted. The end of the strut is now moved 

 by the screws in the opposite direction, this process being 

 repeated until the deflection is reduced to a minimum 

 under the loads applied. This brings the line of thrust 

 of the load into approximate coincidence with the axis 

 of the specimen, and the test may be proceeded with. 



If knife-edge or conical sockets are used, the edges or 

 pointed ends will penetrate the metal of the plates, and it 



FIG. 151. 

 CONSIDERED METHOD OF HOLDING FOR STRUTS. 



is therefore advisable to interpose two small steel plates 

 between the edges or points and the plates of the testing 

 machine. 



153. Example of a Test of a Wrought-iron Column. 



The following sample of what may be expected to take 

 place in a test of a column or pillar is based upon Tet- 

 majer's Tests. 



