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of the specimen at the various stages, so that, as explained when Diagrams Nos. V. 

 and VI. were described, cyclic conditions of material are not represented. The differ- 

 ence between the behaviour of the material when a gradually increasing load was 

 applied for a first time, and when the same load was applied for a second time, was, 

 however, not usually so great as that shown in Curve B, Diagram V., at least with 

 regard to the yielding at the higher loads. At early stages in recovery slightly 

 smaller elongations were obtained on a second loading, but at intermediate stages 

 greater extensions were obtained at the lower loads, and approximately the same exten- 

 sions at the higher. The following table of extensometer readings, obtained from a 

 specimen very similar to the last, may be taken as showing maximum differences, for 

 the material commonly employed in these experiments, between the elongations 

 produced at intermediate stages in recovery by a first and by a second loading. 

 Curves Nos. 6 and 6' of Diagram IX. also show in a striking fashion this difference in 

 elastic condition. 



The effect .produced by a third loading of a specimen usually differed from that 

 produced by a second, but the difference was comparatively very slight. 



To return to Diagram No. VIII., in the lost test of the specimen (illustrated by 

 Curve No. 23 in the second part of the diagram), the load was increased by a quarter 

 of a ton to the square inch at a time ; a gradual falling away from elastic behaviour 

 was recorded, and finally local extension and fracture occurred at a stress of 49^ tons 

 per square inch. This corresponded to about 46 tons per square inch of primitive area. 

 The total elongation which the specimen had received was estimated to be 12 per 

 cent, on an 8-inch length. 



A fresh specimen from the same rod as the above, broken in a single test without 

 allowing intermediate recoveries to take place,* gave an ultimate strength of rather 



* Owing to the specimen breaking in the machine grips (at a stress of 38 tons to the square inch) a 

 partial recovery took place while the specimen was turned down in the centre. The strength given 

 above may therefore be a little too great and the elongation a little too small. 



