334 M. Edlund on the Thermal Phenomena which 



It might be feared that the friction of the wire against the 

 piucer would exercise a considerable disturbing influence on the 

 results, in consequence of the heat which it developes. But the 

 experiments show clearly that there is nothing of the kind ; for 

 they prove that the calorific effects observed when the wire 

 lengthens or shortens in consuming or in developing the same 

 external work are exactly equal, and of contrary sign, which 

 could not have taken place if the heat disengaged by friction in 

 one experiment diminished the disengagement of heat due to 

 elongation, and in the following experiment increased the eleva- 

 tion of temperature due to contraction. 



The first series of experiments was made with a steel wire (a 

 piano string) of 1*14 millim. in diameter. The results are con- 

 tained in the following Table, in which u, u', u 11 designate the 

 three ranges of the galvanometer needle corresponding to the 

 three periods of the experiment above described : — 



Mean . 



M 



can 



Mean . 



Charge of the 



lever . 



. 11-84 



U. 





u'. 



u". 



48-0 





46-0 



97-0 



48-0 





430 



99-0 



45-0 





• • » 



91-0 



45-0 





49-0 



990 



. 46-5 





46"'0 



96-5 



Charge 



of the 



lever. 



. . 6-66 



U. 





u . 



u". 



29-0 





25-0 



435 



26-5 





25-0 



41-0 



• • • 





30-0 



40-0 



31-0 





33-6 



42-0 



34-0 





26-0 





260 





23-0 





. 29-3 





27-1 



41-6 



Charge 



of th 



e lever 



. . 8-38 



u. 





u\ 



u". 



34-0 





280 



57-0 



35-0 





28-0 



53-5 



36-5 





38-0 



53-0 



335 





300 



50-0 



345 





35-0 



57-0 



30-0 





40-0 



56*5 



. 33-9 





33-2 



545 



* M. Edhmd's unit of weight is the Swedish pound. 



