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¹⁰ See for example Ayrton, W.E., Perry, J., ‘On winding electromagnets’, Proceedings of the Physics Society of London, (1882–1884), 5, pp. 230–234CrossRefGoogle Scholar; Thomson, J.J., Newall, H.F., ‘Experiments on the maximum of magnetism of iron rods, especially on the effect of narrow crevasses at right angles to the length’, Proceedings of the Cambridge Philosophical Society, (1886–1889), 6, pp. 84–90Google Scholar; Ewing, J.A., Magnetic Induction in Iron and Other Metals, London, 1891 (chapter X).Google Scholar

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²⁰ The most penetrating biography was written by his son, B. Hopkinson, as a preface to the collected works: Hopkinson, B. ‘Memoir’, op. cit. (19), pp. (ix)–(lxii)Google Scholar. See also Proceedings of the Royal Society, (1898), 17, pp. (xvii)–(xxiv)Google Scholar, and Greig, J., John Hopkinson: Electrical Engineer, London, 1970.Google Scholar An evaluation by a contemporary of his magnetic work is in Ewing, A., An Engineer's Outlook, London, 1933.Google Scholar For an overview of his pure-scientific work see: Hopkinson, J., Original Papers by the Late John Hopkinson Vol. 2 (Scientific Papers), Cambridge, U.K., 1901.Google Scholar

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²⁹ Ibid, p. 232. The diagrams comparing the old and new machines have become crossed over.

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³³ See the footnote on the first page of a sequel to ‘Dynamo-electric machinery’: op. cit. (19), pp. 122–132.Google Scholar (First published as Hopkinson, J. ‘Dynamo-Electric Machinery’ in Proceedings of the Royal Society, (1892).)Google Scholar

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¹²⁸ Ibid., n. 2718–2796.

¹²⁹ Ibid., n. 2797–2845.

¹³⁰ Ibid., n. 2797.

¹³¹ Ibid., n. 2835.

¹³² A general appreciation of Ohm's life and achievement is found in: Lommel, E., ‘The scientific work of George Simon Ohm’, Smithsonian Reports (07 1891), pp. 247–256.Google Scholar A list of Ohm's papers, and of much associated work, is given by Schagrin, , op. cit. (134) belowGoogle Scholar. The memoir usually quoted in this connection is translated into English: Ohm, G.S.. ‘The galvanic circuit investigated mathematically’. From Taylor, R., Scientific Memoirs, vol. ii, London 1841Google Scholar; its sections are dated at various times in 1826 and 1827.

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