TRANSACTIONS 



ROYAL IRISH ACADEMY. 



I.— On the Relation between the Temperature of metallic Conductors, and their 

 Resistance to Electric Currents. By the Rev. Thomas Romney Robinson, 

 D.D.,M.R.I.A.,^-c.&;c. 



Read November 30, 1848. 



In the year 1821, Sir II. Davy discovered that metallic wires resist a voltaic 

 current more as their temperature is raised ; and that this is the case whether 

 they be heated by the current itself or some other means. His memoir con- 

 tains many remarkable facts ; but the imperfect state of rheometric knowledge 

 at that time, and the unsteady action of the batteries which were then in use, 

 prevented him from determining the law of the change. More recently the 

 subject has been examined by E. Becquerel and Lenz, who found the increase 

 of resistance proportional to the temperature. Their researches (to which 

 however, I have not an opportunity of referring) were, I believe, made at tem- 

 peratures little above that of boiling water ; and it seemed desirable to extend 

 them through a wider range, as facts of this nature have an unequivocal rela- 

 tion to the molecular forces and atomic structure of matter. 



The transference of electricity through a wire has nothing in common with 

 the movement of material fluids in a tube, except the analogy of the efiects 

 produced by enlarging the section of the conductor. A much more probable 

 view of its nature is that which refers it to a successive change of tension in 



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