between Metallic Masses having different Temperatures. 27 



led me, pointed out another, and perhaps not less important, 

 analogy, which appeared not to have been before observed, 

 namely, that when the best data are collected, the order of 

 conducting powers of the metals for heat and for electricity is 

 the same. I did not adopt this conclusion till after a mature 

 examination of existing statements, and an extensive series of 

 experiments upon the conducting powers of the metals for 

 heat, made with Fourier's thermometer of contact, which en- 

 abled me, where discrepances occurred between previous ob- 

 servers, to ascertain the truth, and to add some new metals 

 to the list. In the case of electricity, I was a good deal sur- 

 prised to find observers more at one, than in that of heat. The 

 result of these inquiries, which for a time withdrew my atten- 

 tion from the immediate subject under consideration, is con- 

 tained in a paper read to the Royal Society of Edinburgh on 

 the 7th of January 1833*. 



35. The general conclusion at which I then arrived is^hus 

 stated in the paper alluded to : That the arrangement of me- 

 tallic conductors of heat does not differ more from that of those 

 of electricity than either arrangement does alone under the 

 hands of different observers. I shall here quote the provisional 

 arrangements which I have given in that paper, and compare 

 them with the order of vibrations which we have recorded 

 above. 



• The analogy to which I allude was observed by me in autumn 1831 ; 

 and the experiments described in the paper just quoted were made between 

 that period and February 1832. 



t On the subject of the conducting powers for electricity, a beautiful 

 illustration of the application of new discoveries in science to branches al- 

 ready known, has occurred to me since forming these lists. Mr. Faraday 

 has shown, that, according to his beautiful Theory of Magnetism by rota- 

 tion, the Transient Magnetic Energy (as it was formerly termed) of different 

 metals, should bear a relation to their conducting power of metals for 

 electricity. This is most remarkably confirmed by the following Table, 

 given by Mr. Harris in the Philosophical Transactions for 1831, which most 

 E 2 



