1895.] Strains in the Testing of Materials and Structures. 141 



much resembles that of a brass rod in its normal state. Tho following 

 is a test of a turned rod of rolled brass with a section of 0'386 square 

 inch. The length under measurement was 9 inches. 



Load. 







i 



1 



H 



2 



2* 



3 



8* 



4 



4* 







4* 



5 





 5 



H 



o 



Under the higher loads there was a distinct creeping, with a corres- 

 ponding creeping back after the load was removed. 



Taking 163 divisions per ton as the extension under small loads, 

 the value of E is 7160 tons per square inch. 



The last test to be cited is that of a " steel " casting of the specially 

 pure kind now extensively used to form the cores of dynamo magnets. 

 The rod was turned from a steel casting by the makers (Messrs. Edgar 

 Allen and Co.), and had been submitted to the writer for a magnetic 

 test, which had shown it to have exceptionally high permeability 

 under strong magnetic forces. It consisted of nearly pure iron. The 

 diameter was 0'753 inch. 



Difference per 

 Load. Extensometer. half-ton. Set. 



200 



A 237 37 



1 273 36 

 1 310 37 



2 347 37 

 2 384 37 



3 423 39 



204 4 (apparently 



persistent). 



