THERMO-ELECTRIC EFFECTS OF LONG. TENSION IN DIFF. METALS. 



57 



with another carried out after even a few hours only, during which 

 the wires had heen cooled down to the atmospheric temperature, the 

 latter series was usually found to he more to the negative side than 

 the former in the scale of E. M. F., and this to an extent which was 

 indeed comparable with that of the total fluctuation of the thermo- 

 electric E. M. F. Let us cite an example to make my meaning more 

 concrete. The wires tested were cut from the same bundle as that of 

 § 31. After being permanently elongated with a load of 16 kilos, 

 the stretched wire was twice loaded up to the maximum load and 

 unloaded down to zero. The observations then made are given in the 

 fol low i no- table : — 



The wires were then left undisturbed over night and on the next 

 day heated for a while. After two successive loadings and unloadings 

 (0—16 — kilos.) the E. M. F. was measured, as in the following 

 table : — 



