This paper is condensed from my Ph.D thesis ‘Theory and experiment in J.J. Thomson's work on gaseous discharge,’ University of Bath, 1985, in which further details may be found. I am grateful to my supervisor,David Gooding for encouragement and helpful criticism and to the University of Bath for financial support. I have enjoyed the hospitality of Oregon State University while writing this paper.

¹ Thomson, J. J., ‘Cathode rays’ (Friday evening meeting of the Royal Institution, 30 April 1897), The Electrician, (1897), 39, p. 104.Google Scholar

² For example, Anderson, D., The Discovery of the Electron, Princeton, N.J., 1964Google Scholar; Crowther, J. G., British Scientists of the Twentieth Century, London, 1952Google Scholar; Keller, A., The Infancy of Atomic Physics, Oxford, 1983Google Scholar; Price, D., ‘Sir J. J. Thomson OM, FRS’, Nuovo Cimento Supplement, (1957), 4, p. 1609CrossRefGoogle Scholar; 4th Rayleigh, Lord, The Life of Sir J. J. Thomson, Cambridge, 1942Google Scholar; Thomson, G. P., J. J. Thomson and the Cavendish Laboratory in his Day, Garden City, N. Y., 1964Google Scholar; Whittaker, E., A History of the Theories of Aether and Electricity: the Classical Theories, London, 1951.Google Scholar

³ Heilbron points this out in his DSB biography of Thomson. He takes an independent line from other writers [op. cit. (2)] and correctly emphasizes the importance of Thomson's commitment to Maxwell's electromagnetism and the mechanical philosophy in guiding the discharge work. However, he still assigns the cathode ray controversy unwarranted prominence. In particular, he sees the discovery of X-rays as an outcome of controversy rather than vice versa. Heilbron, J. L., ‘Thomson, Joseph John’, Dictionary of Scientific Biography, 13, p. 362.Google Scholar

⁴ Thomson, , op. cit. (1)Google Scholar; Thomson, J.J., ‘Cathode rays’, Philosophical Magazine (1897), V, 44, p. 293.Google Scholar

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⁶ Lorentz, H. A., ‘La théorie électromagnetique de Maxwell et son application au corps mouvants’, Archives Neerlandaises, (1892), 25, p. 363.Google Scholar

⁷ McCormach, R., ‘H. A. Lorentz and the electromagnetic view of nature’, Isis, (1970), 61, p. 459.CrossRefGoogle Scholar

⁸ Throughout this paper I use the term ‘subatomic’ to signify not only the small size of the corpuscle but also its property of being an essential and universal constituent of atoms.

⁹ Thomson, , op. cit. (4) p. 313.Google Scholar

¹⁰ Ibid. Kelvin was reviving Boscovitchean ideas at this time, e.g., ‘Contact electricity and electrolysis according to Father Boscovitch’, Nature, (1897), 56, p. 84.Google Scholar

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¹³ For example, Anderson, , op. cit. (2)Google Scholar; Whittaker, , op. cit. (2).Google Scholar

¹⁴ One of the most complete traditional accounts of the controversy is given in Turpin, B., ‘The discovery of the electron: the evolution of a scientific concept 1800–1899’; Ph.D dissertation, University of Notre Dame, Indiana, 1980Google Scholar, Dissertation Abstracts International order no. 8020971. Turpin recognizes that Thomson was not much interested in cathode rays until 1896 but does not emphasize this enough. Nor does she go to the realization that virtually no-one in Britain was interested in cathode rays.

¹⁵ Crookes, W., ‘On radiant matter’, Nature, (1879), 20, p. 419.Google Scholar

¹⁶ For example, Goldstein, E., ‘On the electric discharge in rarefied gases’, Philosophical Magazine, (1880), V, 10, pp. 173, 234Google Scholar; (1882), V, 14, p. 366; Weidemann, E., ‘On the electric discharge in gases’, Philosophical Magazine, (1884), V, 18, pp. 35, 85.Google Scholar

¹⁷ Hertz, H., ‘Über Kathodenstrahlen’, Annalen der Physik und Chemie, (1883), 19, p. 782.CrossRefGoogle Scholar

¹⁸ Hertz, H., ‘Über den Durchgang der Kathodenstrahlen durch dunne Metallschichten’, Annalen der Physik und Chemie, (1892), 45, p. 28.CrossRefGoogle Scholar

¹⁹ Lenard, P., ‘Über Kathodenstrahlen’, Verhandlunger der Gesellschaft Deutsche Natforscher und Aerzte, (1893), 2, p. 36.Google Scholar ‘Über Kathodenstrahlen in Gasen von atmosphärischern Druck und im äussersten Vacuum’, Annalen der Physik und Chemie, (1894), 51, p. 225Google Scholar; ‘Über die magnetische Ablenkung der Kathodenstrahlen’, Annalen der Physik und Chemie, (1894), 52, p. 23.Google Scholar

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²³ Thomson, J.J., ‘On the cathode rays’, Proceedings of the Cambridge Philosophical Society, (1897), 9, p. 243Google Scholar; op. cit. (1); op. cit. (3).

²⁴ Kaufmann, W., ‘Die magnetische Ablenkbarkeit der Kathodenstrahlen und ihre Abhängigkeit vom Entladungspotential’, Annalen der Physik und Chemie, (1897), 61, p. 544CrossRefGoogle Scholar; (1897), 62, p. 596; Wiechert, E., ‘Ergebniss einer Messung der Geschwindigkeit der Kathodenstrahlen’, Schriften der physikalischökonomisch Gesellschaft zu Königsberg, (1897), 38, p. 3.Google Scholar

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²⁷ Anderson, , op. cit. (2), p. 29.Google Scholar

²⁸ Goldstein, , op. cit. (16)Google Scholar; Wiedemann, , op. cit. (16).Google Scholar

²⁹ I do not claim accuracy for these numbers as some sort of judgement had to be made as to whether papers represented a contribution to the controversy, or were merely concerned with the striking visual effects of cathode rays. The dividing line is fairly arbitrary. In addition, many contributions to Nature and The Electrician were indirect, contained in reports of meetings and editorial notices. Again, a judgement had to be made about how brief a report warranted inclusion. But the figure lists the original British contributions and the trend is very clear. The inclusion of all the minor notices would serve to exaggerate the peak of interest in 1896 without altering the numbers prior to 1896.

³⁰ A detailed study of the German ether theories and attitude to the controversy is badly needed. Most accounts are written from the point of view of the winning particle theorists. The best account is Turpin, 's op. cit. (14).Google Scholar

³¹ Thomson, J.J., ‘On the electric and magnetic effects produced by the motion of electrified bodies’, Phil. Philosophical Magazine, (1881), V, 11, p. 229.Google Scholar

³² Thomson, J.J., Notes on Recent Researches in Electricity and Magnetism, Oxford, 1893Google Scholar, hereafter referred to as Recent Researches.

³³ Cambridge University Library MS, Add 7654 NB36.

³⁴ This difference between Schuster and Thomson was probably largely due to the conditions under which they performed their experiments. Neither quotes figures for the pressures they were working at, but Schuster appears to have expended more time in evacuating his apparatus. At the relatively high pressures of Thomson's experiments, cathode rays were not a significant phenomenon, but they probably were in Schuster's experiments. Schuster, A., ‘Experiments on the discharge of electricity through gases: a sketch of a theory’ (Royal Society Bakerian Lecture), Proceedings of the Royal Society, (1884), 37, pp. 317, 495CrossRefGoogle Scholar; ‘Experiments on the discharge of electricity through gases’, Proceedings of the Royal Society, (1887), 42, p. 371Google Scholar; ‘The passage of electricity through gases’, British Association Report, (1889), p. 510Google Scholar; ‘The disruptive discharge of electricity through gases’, Philosophical Magazine, (1890), V, 29, p. 182Google Scholar; op. cit. (20).

³⁵ Thomson, , op. cit. (32), p. 121.Google Scholar

³⁶ The Electrician, (1894), 33, p. 475.Google Scholar

³⁷ FitzGerald, C., ‘On cathode rays in gases under atmospheric pressure and in extreme vacua’, The Electrician, (1894), 32, p. 573Google Scholar; ‘On Herr Lenard's experiments on the magnetic action of cathode rays’, The Electrician, (1894), 33, p. 151Google Scholar; Thomson, , op. cit. (21).Google Scholar

³⁸ Schuster, , op. cit. (20).Google Scholar

³⁹ As suggested by Keller, , op. cit. (2).Google Scholar

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⁴² Batelli, Note in Nature, (1896), 54, p. 62.Google Scholar

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⁴⁶ FitzGerald, G., ‘Review of Hertz's work’, Nature, (1896), 55, p. 7.Google Scholar

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⁴⁸ Thomson, J.J. ‘Presidential Address to Section A’, British Association Report, (1896), p. 194.Google Scholar

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⁵¹ See works referenced in note (2). Heilbron [op. cit. (3)], however, correctly assesses Hertz's experiment as relatively unimportant.

⁵² FitzGerald, , op. cit. (43).Google Scholar

⁵³ Sharlin, H., The Convergent Century: The Unification of Science in the Nineteenth Century, London, 1966Google Scholar; Wilson, D.B., ‘The thought of late Victorian physicists: Oliver Lodge's ethereal body’, Victorian Studies, (1971), 15, p. 29.Google Scholar

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⁵⁵ Klein examines the status of the mechanical philosophy and visualisable analogies, particularly Maxwell's use of them: Klein, M. J., ‘Mechanical explanation at the end of the nineteenth century’, Centaurus, (1972), 17, p. 58.CrossRefGoogle Scholar Topper has studied Thomson's commitment to mechanism in general, and to Maxwell in particular, in his thesis and two papers: Topper, D., ‘J. J. Thomson and Maxwell's Electromagnetic Theory’, Ph.D dissertation, Case Western Reserve University, 1970Google Scholar, University Microfilms order No. 71–19065; ‘Commitment to mechanism: J.J.Thomson, the early years’, Archive for the History of Exact Sciences, (1971), 7, p. 393Google Scholar; ‘To reason by means of images: J. J. Thomson and the mechanical picture of nature’, Annals of Science, (1980), 37, p. 31.Google Scholar The last of these is particularly important for containing details of Thomson's vortex analogies and the way he transposed them from one situation to another. However, Topper deals exclusively with Thomson's theoretical work. He does not consider any experimental stimulus for the theory changes he describes, nor the influence of these theoretical commitments on Thomson's experimental work. As Wheaton has pointed out, the mechanical philosophy was implicit in Thomson and Schuster's cathode ray experiments: they assumed that macroscopic mechanical laws carried over into the microscopic realm: Wheaton, B., The Tiger and the Shark, Cambridge, 1983, p. 6.CrossRefGoogle Scholar In my thesis and a forthcoming paper, I discuss other ways in which the mechanical philosophy influenced Thomson's approach to experiment: Falconer, I., ‘J. J. Thomson; an experimental genius?’ (1986)Google Scholar, submitted to Social Studies in Science.

⁵⁶ Thomson, J.J., ‘On a theory of the electric discharge in gases’, Philosophical Magazine, (1883), V, 15, p. 427.Google Scholar

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⁶³ Thomson, J.J., ‘A theory of the connection between cathode and Röntgen rays’, Philosophical Magazine, (1898), V, 45, p. 172Google Scholar; ‘On the connexion between the chemical composition of a gas and the ionisation produced in it by Röntgen rays’, Proceedings of the Cambridge Philosophical Society, (1898), 10, p. 10Google Scholar; ‘On the charge of electricity carried by the ions produced by Röntgen rays’, Philosophical Magazine, (1899), V, 47, p. 253Google Scholar; ‘The genesis of the ions in the discharge of electricity through gases’, Philosophical Magazine, (1900), V, 50, p. 278.Google Scholar

⁶⁴ For example, Thomson, J.J., ‘On the passage of electricity through hot gases’, Philosophical Magazine, (1890), V, 29, p. 358Google Scholar; op.cit. (58).

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⁶⁶ Peace, J., ‘On the potential difference required to produce a spark between two parallel plates in air at different pressures’, Proceedings of the Royal Society, (1892), 52, p. 99.CrossRefGoogle Scholar Peace was a research student at the Cavendish Laboratory.

⁶⁷ Rutherford, E. and Thomson, J.J., ‘On the passage of electricity through gases exposed to Röntgen rays’, Philosophical Magazine, (1896), V, 42, p. 392.Google Scholar

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⁷¹ Cambridge University Library MS, Add 7654 NB39. My thesis contains a much more detailed account of this notebook and the evidence it contains of Rutherford and Thomson's theoretical expectations.

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⁷⁶ Cambridge University Library MS, Add 7654 NB40. This notebook contains the notes for a series of lectures Thomson gave at Princeton in October 1896. The notes were probably written in August or September 1896, and represent an earlier viewpoint than the Thomson and Rutherford ionization paper, op. cit. (67). The lectures were published in 1898 as The Discharge of Electricity Through Gases, op. cit. (49), by which time Thomson had edited and revised them in the light of his recent cathode ray work.

⁷⁷ The prevailing theory of magnetization was that suggested by Weber and subsequently developed by Maxwell and by Ewing. It supposed that a magnet consisted of small magnetic particles which were initially randomly oriented but became aligned under a magnetic force. Saturation occurred when all the particles were aligned.

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⁷⁹ Op. cit. (71).

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⁸³ For example, the notes for his Princeton lectures, op. cit. (76).

⁸⁴ Rutherford verified this assumption in 1897: Rutherford, E., ‘The velocity and rate of recombination of the ions of gases exposed to Röntgen radiation’, Philosophical Magazine, (1987), V, 44, p. 422.Google Scholar

⁸⁵ Ibid.

⁸⁶ This tradition has been interpreted very well by Buchwald, J., From Maxwell to Microphysics, Chicago, 1985.Google Scholar

⁸⁷ ‘Notes for lectures on electricity’ (c. 1886), Cambridge University Library MS, Add 7654 NB33 f5.

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⁸⁹ Here, it may be significant that Napier Shaw, at the Cavendish, was compiling a report on electrolysis for the British Association in 1890: Shaw, W., ‘Report on the present state of our knowledge in electrolysis and electrochemistry’, British Association Report, (1890), p. 185.Google Scholar

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¹⁰¹ Op. cit. (90).

¹⁰² Mayer, A., ‘Floating magnets’, Nature, (1878), 17, p. 487.Google Scholar Thomson used this analogy again later to guide his corpuscular theory of the atom, long after he had abandoned the vortex atom. Thomson was not the only physicist to use Mayer's experiments as a guide for his atomic theory: see Snelders, H., ‘A.M. Mayer's experiments with floating magnets and their use in the atomic theories of matter’, Annals of Science, (1976), 33, p. 67.CrossRefGoogle Scholar

¹⁰³ Op.cit. (90).

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¹⁰⁷ Ibid.

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¹⁵⁴ Professor of Physics at the University of Moscow.

¹⁵⁵ ‘Bien que les travaux de J. J. Thomson soient plus nombreux que ne le sont ceux de W. Kaufmann et embrassent un plus grand nombre de phénomènes, non seulement explorés au point de vue experimentale, mai aussi élucides theoriquement, nos connaissances dan e domaine de physique n'auraient pas atteint en ce moment leur niveau actuel sans les recherches de W. Kaufmann.…’ (Oumoff to the Nobel Foundation 31 January 1904, Nobel Foundation archives).

¹⁵⁶ ‘Les résultats de ces expériences ont conduit pour la premiere fois à la notion d'un corpuscle cathodique bien plus petit que l'atome d'hydrogene’, (P. and M. Curie to the Nobel Foundation 26 December 1904, Nobel Foundation archives).

¹⁵⁷ ‘Ces conceptions théoriques ont recu diverses confirmations parmi lesquelles nous citerons les recherches recentes de Mr Kaufmann qui sont favorable a l'opinion que la mass des corpuscles négatifs émis par le radium (rayons β), est entierement de nature électromagnétique’, (ibid.).

¹⁵⁸ Thomson, , op. cit. (31).Google Scholar

¹⁵⁹ Thomson, , op. cit. (135).Google Scholar FitzGerald had in effect suggested this when postulating that cathode rays were ‘free electrons’, as had des Coudres with his ‘weightless convergent lines of force structure’ in the ether.

¹⁶⁰ These developments are discussed in McCormach, , op. cit. (7).Google Scholar

¹⁶¹ Hacking, I., Representing and Intervening, Cambridge, 1983.CrossRefGoogle Scholar

¹⁶² McCormach points out the significance of this to Lorentz, who recast his theory to treat individual electrons, and was able to determine experimentally the velocity dependence of the electron mass. McCormach, , op. cit. (7), p. 475.Google Scholar