Abstract
IN June 1849, J. P. Joule announced the results of extensive researches carried out in Manchester, in which he found that the expenditure of energy, in whatever form, is always accompanied by the production ef a corresponding amount of heat. Prior to this, there had been considerable disagreement among men of science concerning the nature of heat ; some held it to be a material fluid (called caloric) which permeated the space between partieles composing a hot body, while others attributed it to the mechanical energy of these same partieles which were to be regarded as being in rapid motion or vibration. Joule's work settled the controversy in favour of the seoond alternative, and thereby laid the foundation for the modern theory of heat. With a water-friction apparatus Joule obtained the experimental result that to heat a pound of water through one degree F. requires 772 ft. Ib. of mechanical energy. This original apparatus is preserved at the Science Museum, South Kensington, London, S.W.7, and is on special exhibition there until the end of July.
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Exhibition of Joule's Water-Friction Apparatus. Nature 164, 17–18 (1949). https://doi.org/10.1038/164017d0
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DOI: https://doi.org/10.1038/164017d0