Effects on First Loading a Wire. 621 



In fig. 1 are shown the results obtained in three successive 

 tests on a wire immediately after being unwound from a 



(1) Behaviour of wire on first test.' 



(2) „ „ immediately following (1). 



( 3 ) v » v » (2). 



bobbin of about 8 cm. diameter. The first curve indicates 

 the anomaly of a wide separation in the upper part from the 

 two following ones. It does not seem to show any definite 

 yield-point as they do, but a continuously increasing extension 

 for the same increase of tension. A certain amount of per- 

 manent extension remains after the load has been removed. 

 For the sake of making the comparison of the curves easier, 

 this permanent extension has not been shown in the diagrams. 

 AH the curves have been moved along the axis, so that the 

 position of the zero of tension might be the same. This 

 gradual increase of extension with the same increase of load 

 could scarcely be due to kinks in the wire, as the process of 

 removing the insulation was carried out with the wire in 



