On Certain Thermoelectric Effects of 

 Stress in Iron. 



By 



C. G. KnoU, D. Sc, F.R.S.E. 



Professor of Physics, Imperial University. 

 And 



S. Kimura, Ri^akushi. 



Since the (li.^covery mrifle by Tlioni.^^on thnt the thermoelectric 

 propertie.:! of wire:; of certain metal.^ were altered l)y tension, the sub- 

 ject has lieen studied cxperimentnlly by various scientific men. Of 

 these we may mention more particularly Le Ivoux, von Tunzelman, 

 Colin, and Ewino;-. Tlie work done by Cohn and Ewing is of special 

 im])ortance ; and the latter's investigation for iron is the most com- 

 plete that lias been carried out. Eeference will be made to their 

 results hereafter. It is sufficient at present to point out one respect 

 in wliich the work of these experimenters lacks completeness. In all, 

 the method (^f exjX'riment consisted in studying the effects of stress 

 upon the thermoelectric properties of a wire, whose junctions with tlie 

 other es.^ential wire of the circuit were kept at steady temperatures. 

 The variations of stress were, in the best experiments, carried through 

 a cycle ; and at different successive stages tlie thermoelectric current 

 was measured on a suitable galvanometer. The observed changes in 

 the electromotive force might be due to either of two quite different 

 effects ; and the experimental methods adopted could give no criterioi^ 



