156 



COMPRESSION TESTS. 



great force, so that it is necessary, for the safety of the 

 operator, to surround the bar with wood or sacking, which 

 will prevent the pieces from being shot outwards. Tin- 

 compressive strain of cast iron is small, and measurements 

 are not usually taken Aluminium shows a considerable 

 amount of plasticity, but cracks under a high load. 



EXAMPLE OF COMPRESSION TEST. 



Date : January 21st, 1899. 

 Specimen of: Copper. 

 Tested in : Compression. 



r, . . , , f 0'95 in. < 

 Original dimensions : -j Q.^QO 



dia. 2 '5 in. long, 

 in., original area. 



95. The Compression Diagram. On Fig. 74 is shown 

 a diagram which has been plotted from the results of the 

 test quoted above. Here, as before, loads are plotted 

 horizontally and lengths upwards, or, in other words, 

 compressions downwards. 



