590 BELL SYSTEM TECHNICAL JOURNAL 



The curves given for fatigue endurance show the results for each 

 specimen tested. The shape of the fatigue endurance curve for these 

 metals is similar to those published previously for other metals. 



A special form of fatigue machine has been developed to test sheet 

 metals. This machine will accommodate forty specimens. Capacity is 

 thereby provided so that as many as five specimens may be employed 

 for each of four materials at two deflections under test. 



