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II. On the relative powers of various metallic substances as con- 
ductors of electricity. By Mr. William Snow Harris, of 
Plymouth, Surgeon. Communicated by J. Knowles, Esq. 
F. R. S. November 14, 1 826. 
Read December 14, 1826. 
The relation between metallic bodies, as conductors of elec- 
tricity, has engaged the attention of those whose talents 
have, at various periods, enriched that branch of science ; I 
enter therefore upon a further investigation of this interest- 
ing subject with much diffidence ; but having, by an easy 
method, obtained a series of results, apparently calculated to 
advance our knowledge of it, I am led to hope that a short 
account of my inquiries may be honoured by the notice of the 
Royal Society. 
It has been long since observed by one of the most active 
contributors * to the success of modern science, that the heat 
evolved by a metallic body, whilst transmitting an electrical 
charge, is in some inverse ratio to its conducting power — a 
principle generally admitted, not only as a reasonable deduc- 
tion, but also as being established by a great variety of facts; 
I have therefore sought to measure the relative degree of 
heat, so evolved, by various metallic substances in a gazeous 
medium such as air, and thus to discover their precise rela- 
tions as conductors of electricity. 
I employed for this purpose a very simple instrument, 
( represented by fig. 1 . in the annexed plate, ) which may be 
* Mr. Children’s Experiments with a large Galvanic Battery. 
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