Published online by Cambridge University Press: 05 January 2009
André-Marie Ampère's contributions to electrodynamics came at a late stage in an unconventional career. In 1820, he had reached the age of forty-five and had not as yet done any systematic research in physics. As a member of the mathematics section of the Académie des Sciences, his only significant contributions to the physical sciences had been some constructive criticisms of Fresnel's wave theory of light and three memoirs on chemical classification and gas theory. Meanwhile, his longstanding interests in metaphysics and epistemology had resulted in pointed methodological and philosophical attitudes which both motivated and structured his subsequent work in electrodynamics. Not surprisingly, events during the first few months of Ampère's research included many unplanned and unexpected encounters as this wildly enthusiastic theoretician grappled for the first time with the recalcitrant complexity of actual experimentation in an uncharted new domain.
2 Ampère, A-M., Théorie des Phénomènes Électro-dynamiques, Uniquement Déduite de l'Expérience, Paris, 11 1826.Google Scholar
4 Maxwell, J., A Treatise on Electricity and Magnetism, 3rd edn., 2 vols, London, 1891Google Scholar; reprinted, New York, 1954, ii, pp. 175–176.
5 Blondel, C., ‘Ampère and the programming of research’, Isis, (1985), 76, pp. 559–561CrossRefGoogle Scholar; Williams, L. Pearce, ‘What were Ampère's earliest discoveries in electrodynamics?’, Isis, (1983), 74, pp. 492–508CrossRefGoogle Scholar; Williams, L. Pearce, ‘Reply to “Ampère and the programming of research”’, Isis, (1985), 76, p. 561.Google Scholar
7 Hofmann, J., ‘Ampère, electrodynamics, and experimental evidence’, Osiris, (1987), 3 (in press)Google Scholar; Mendoza, E., ‘Ampère's experimental proof of his law of induction: i2αi1’, European Journal of Physics, (1985), 6, pp. 281–286CrossRefGoogle Scholar; Williams, L. Pearce, ‘Why Ampère did not discover electromagnetic induction’, American Journal of Physics, (1986), 54, pp. 306–311CrossRefGoogle Scholar; Williams, L. Pearce, ‘Faraday and Ampère: a critical dialogue’, in: Gooding, D. and James, F. (eds), Faraday Rediscovered: Essays in the Life and Work of Michael Faraday 1791–1867, New York, 1985, pp. 83–104.CrossRefGoogle Scholar
9 Ampère's notes for Lessons 25, 26 and 27 are most important and are to be found in the archives of the Académie des Sciences, carton 16, chemise 261.
12 There are extensive manuscript notes on this subject preserved in the archives of the Académie des Sciences, carton 10, chemise 203. They can be dated as written between 1801–1802.
13 Ampère emphasized this point in several publications including his famous 1826 memoir, op. cit. (2). The most commonly cited version of this monograph is the slightly revised 1827 publication: ‘Mémoire sur la théorie mathématique des phénomènes électro-dynamiques, uniquement déduite de l'expérience…’, Mémoires de l'Académie Royale des Sciences de l'Institute de France. Année 1823, (1827), 6, pp. 175–387Google Scholar, on p. 294.
15 Biot, J.B., ‘Borda’, Biographie Universelle, 5, (ed. Michaud, ), Geneva, 1812; 1854 edition, p. 60.Google Scholar For a good discussion of the context for Biot's phrase, see Frankel, E., ‘J.B. Biot and the mathematization of experimental physics in Napoleonic France’, Historical Studies in the Physical Sciences, (1977), 8, pp. 33–72.CrossRefGoogle Scholar
16 Biot, J.B., Précis Élémentaire de Physique Expérimental, 2 vols, Paris, 1817Google Scholar; 2nd edn., 1821; 3rd edn., 1824; quoted passage from 3rd edn., vol. 1, p. 5.
18 For a thorough analysis of Poisson's contributions to the physics of ponderable matter, see Arnold, D.H., ‘The Mecanique Physique of Simeon Denis Poisson: the evolution and isolation in France of his approach to physical theory (1800–1840)’, Archive for History of Exact Sciences, (1983), 28, pp. 243–367CrossRefGoogle Scholar; (1983), 29, pp. 37–51; (1984), 29, pp. 287–307.
19 Biot, J.B., ‘Lettre de Mr. Biot, membre de l'Académie des Sciences, etc. au Prof. Pictet, correspondant de l'Académie et l'un des rédacteurs de ce recueil’, Bibliothèque Universelle des Sciences, Belles-Lettres, et Arts, (1816), 2, pp. 81–86Google Scholar, on pp. 84–85.
20 For example, see the following announcement written in November 1820: Biot, J.B., ‘Advertissement sur la seconde édition du Traité de Physique Élémentaire de M. Biot’, Annales de Chimie et de Physique, (1820), 15, pp. 331–335.Google Scholar
21 Biot, J.B., ‘Sur l'aimantation imprimée aux métaux par l'électricité en mouvement: lu à la séance publique de l'Académie des Sciences, le 2 avril, par M. Biot’, Journal des Savans, (1821), Avril, pp. 221–235Google Scholar, on p. 235.
22 L.P. Williams has recently clarified this point; see Williams, , op. cit. (5), 1983, p. 498.Google Scholar
24 Félix Savart published extensively in the areas of acoustics and elasticity. Biot helped him to become established within the Parisian scientific community, and Savart's interest in electromagnetism seems to have been limited to this early stage in his career. See Dostrovsky, S., ‘Félix Savart’, D.S.B., vol. 12, pp. 129–130.Google Scholar
25 Biot, J.B. and Savart, F., ‘Note sur le magnétisme de la pile de Volta’, Annales de Chimie et de Physique, (1820), 15, pp. 222–223Google Scholar, on p. 223; also published as ‘Sur la mesure de l'action exercée à distance sur une particule de magnétisme’, Journal de Physique, de Chimie, d'Histoire Naturelle et des Arts, (1820), 91, p. 151.Google Scholar
26 To my knowledge, no direct report of Biot's 18 December presentation has survived. Biot gave a fairly detailed summary of both sets of measurements at the public session of the Académie on 2 April 1821, and he published this discourse shortly thereafter; see Biot, , op. cit. (21).Google Scholar Most of this publication was incorporated into the second edition of Biot's Précis, op. cit. (16), and was expanded into a much larger version in the 1824 third edition.
28 Biot, , op. cit. (16) 3rd edn., vol. 2, pp. 742–746Google Scholar; the relevant passages from the 1821 and 1824 editions are conveniently contrasted in Mémoires sur l'Électrodynamique, vols 2 and 3 of Collection de Mémoires Relatifs à la Physique, 5 vols, Paris, 1885–1887; vol. 2, pp. 116–120.Google Scholar
31 The rivalry had become quite heated by the time of the annual public session of the Académie on 2 April 1821. Biot took the occasion to claim that Ampère's discovery of attractions and repulsions between conductors should be understood in terms of the magnetic states of the conductors. See Biot, , op. cit. (21).Google Scholar
34 As early as the 8 January 1821 meeting of the Académie, Ampère proposed that the electric currents within magnets might be confined to circuits around individual molecules. This was only presented as a possibility at this point due to lack of experimental evidence and because Ampère assumed that the summation of these molecular currents would be equivalent to large scale currents to which he could more readily apply his force law. The notes for Ampère's lecture are preserved in the archives of the Académie des Sciences, carton 8, chemise 166.
35 This important manuscript fragment seems to be a rejected draft for the concluding part of the long memoir Ampère eventually presented to the Acadèmie on 26 December 1820: Ampère, ‘Suite du mémoire sur l'action mutuelle entre deux courans électriques, entre un courant electrique et un aimant ou le globe terrestre, et entre deux aimans’, Annales de Chimie et de Physique, (1820), 15, pp. 170–218.Google Scholar The manuscript is preserved in the archives of the Académie des Sciences, canon 8, chemise 158. It has been partially edited in Blondel, C., ‘Sur les premières recherches de formule électrodynamique par Ampère (octobre, 1820)’, Revue d'Histoire des Sciences et Leurs Applications, (1978), 31, pp. 53–65.CrossRefGoogle Scholar
36 When Ampère began teaching physics at the Collège de France in November 1824, he and Joseph Liouville composed a long manuscript draft entitled ‘Théorie mathématique des phénomènes électro-dynamiques’. Although never published, this treatise includes a symmetry proof by Liouville in support of Ampère's longstanding assumption that the electrodynamic force lies along the line joining two current elements. The manuscript is in the archives of the Académie des Sciences, carton 11, chemise 208 bis.
37 Archives of the Académie des Sciences, carton 8, chemise 158; edited by Blondel, , op. cit., (35) p. 64.Google Scholar
38 Ibid. A similar argument appears in one of Ampère's earliest publications in electrodynamics: ‘Analyse des mémoires lus par M. Ampère à l'Acadèmie des Sciences dans les séances des 18 et 25 septembre, des 9 et 30 octobre 1820’, Annales Générales des Sciences Physiques, (1820), 6, pp. 238–257Google Scholar, on pp. 247–248.
39 Ampère, A-M. and Babinet, J., Exposé des Nouvelles Découvertes sur l'Électricité et le Magnétisme de MM. Oersted, Arago, Ampère, H. Davy, Biot, Erman, Schweiger, De La Rive, etc., Paris, 1822.Google Scholar Ampère mentions the completion date in a 23 January 1822 letter to Faraday edited in Ross, S., ‘The search for electromagnetic induction 1820–1831’, Notes and Records of the Royal Society, (1965), 20, pp. 184–219CrossRefGoogle Scholar; on pp.217–218. Babinet composed most of the Exposé but with important additions and corrections by Ampére. A valuable set of proof sheets for the first nineteen sections has survived; these provide considerable insight into Ampère's thinking during this period, particularly in the case of passages which Ampère did not correct at this time but which he later realized were incorrect; archives of the Académie des Sciences, carton 11, chemise 208.
47 Ampère, , ‘Notes de M. Ampère sur les lectures qu'il à faites à l'Académie des Sciences’, Journal de Physique, de Chimie, d'Histoire Naturelle et des Arts (abbreviated hereafter as Journal de Physique), (1820), 91, pp. 166–169Google Scholar; on p. 168. Ampère's claim about this observation and much of the rest of the chronology in ‘Notes’ were repeated in de Laumont, G., ‘Note sur les expériences électro-magnétiques de MM. Oersted, Ampère et Arago, relatives à l'identité de l'aimant avec l'électricité’, Annales des Mines, (1820), 5, pp. 535–546Google Scholar; on p. 544. Ampère identifies Laumont as the author of this unsigned report in a 21 February 1821 letter to Roux-Bordier, ; Correspondance du Grand Ampère, de Launay, L. (ed.), 3 vols, Paris, 1936–1943 (abbreviated hereafter as Correspondance), vol. 2, p. 567.Google Scholar
48 See the quoted passage referenced by (43).
49 L. Pearce Williams has argued for a 25 September date but can cite no textual evidence. Why would Ampère say that his anomalous discovery suddenly delayed his plans to test his force law hypothesis if he made that discovery prior to the detection of electrodynamic forces between linear currents? As always, it is possible that Ampère simply confused the order of his own discoveries. For further discussion of this issue, see Williams, and Blondel, , op. cit. (5).Google Scholar
52 Ampère, Archives of the Académie des Sciences, carton 8, chemise 158. For one of Ampère's fullest published discussions of this issue, see Ampère, , op. cit. (13), pp. 199 and 296–302.Google Scholar
53 To my knowledge, no immediate record was made of what Ampère said at the 6 November meeting of the Académie. For what are probably the earliest recorded recollections by Ampère himself, see Ampère, , op. cit. (47), p. 168.Google Scholar A page of Ampère's notes for his presentation is in the Archives of the Académie des Sciences, carton 8, chemise 160.
55 In Ampère's most detailed description of his demonstrations, he refers to an instrument of the type shown in Fig. 3; Ampère, , op. cit. (47), pp. 168–169.Google Scholar For a few additional details, see Laumont, , op. cit. (47), pp. 543–546Google Scholar; Ampère, , op. cit. (41), pp. 175–176 and 208–209Google Scholar; and a set of notes for Ampère's 26 December 1820 lecture to the Académie, Archives of the Académie des Sciences, carton 8, chemise 164.
56 Ampère, , ‘Note sur un Mémoire lu à l'Académie royale des Sciences, dans la séance du 4 décembre 1820’, Journal de Physique (1820), 91, pp. 226–230.Google Scholar
57 Ibid., pp. 226–227. A more detailed argument is provided in a manuscript draft for Ampère's memoir: Archives of the Académie des Sciences, carton 8, chemise 162.
58 Ibid., p. 229. Ampère adopted the notation of n and k for his two parameters during 1821. He originally simply used r–2 for the assumed distance dependency and wrote the parameter k as a ratio n/m to express the fact that it determines the relative strength of two forces.
59 This point is discussed in detail in J.R. Hofmann, ‘The great turning point in André-Marie Ampère's research in electrodynamics: a truly “crucial” experiment’, 1982 Ph.D. dissertation, University of Pittsburgh, University Microfilms order no. 8318183.
60 The primary sources for these arguments are the unpublished manuscripts pertaining to Ampère's lectures to the Académie during December 1820 and January 1821: Archives of the Académie des Sciences, carton 8, chemises 162, 163 and 166. They are discussed in Hofmann, , op. cit. (59).Google Scholar
63 Ampère, , ‘Note sur deux mémoires lus par M. Ampère à l'Académie royale des Sciences, le premier dans la séance du 26 décembre 1820; le second dans les séances des 8 et 15 Janvier 1821’, Journal de Physique, (1821), 92, pp. 160–165Google Scholar; on p. 161. The same passage appears in Ampère, , ‘Exposition dumoyen par lequel il est facile de s'assurer directement, et par des expériences précises, de l'exactitude de la loi des attractions et répulsions des courans électriques, suivie de quelques observations sur cette loi. Mémoire lu le 26 décembre 1820’, Annales des Mines, (1820), 5, pp. 553–558Google Scholar; on p. 554.
64 Ampère, Archives of the Académie des Sciences, carton 8, chemise 164.
66 Ampère, , op. cit. (63), pp. 161–163.Google Scholar To my knowledge, the engraving depicted in Fig. 5 was used for the first time in Ampère's republication of his Annales des Mines article; Ampère, , op. cit. (63).Google Scholar This reprint appeared in Ampère's collection of memoirs which in its second edition was given the title, Recueil d'Observations Électro-dynamiques Contenant Divers Mémoires, Notices, Extraits de Lettres ou d'Ouvrages Périodiques sur les Sciences, Relatifs a l'Action Mutuelle de Deux Courans Électriques, à Celle qui Existe entre un Courant Électrique et un Aimant ou le Globe Terrestre, et à Celle de Deux Aimans l'Un sur l'Autre, 2nd edn., Paris, 1822, pp. 87–92.Google Scholar For details on the two editions of this collection, see Williams, , op. cit. (5), 1983, p. 494.Google Scholar
68 Ampère, , ‘Exposé sommaire des divers mémoires lus par Mr. Ampère a l'Académie Royale des Sciences de Paris, sur l'action mutuelle de deux courans électriques, et sur celle qui existe entre un courant électrique et le globe terrestre ou un aimant’, Bibliothèque Universelle des Sciences, Belles-Lettres et Arts, (1821), 16, pp. 309–319Google Scholar; see pp. 311 and 318.
71 For an interesting discussion of ‘construals’ as ‘flexible, quasi-linguistic messengers between the perceptual and the conceptual’, see Gooding, D., ‘How do scientists reach agreement about novel observations?’, Studies in History and Philosophy of Science, (1986), 17, pp. 205–230.CrossRefGoogle Scholar Gooding's examples are drawn from the electrodynamics of Ampère's English contemporaries: Davy, Faraday and Barlow. This group rejected Ampère's reduction of electrodynamics to central forces. Engravings such as those shown in Figs 1 and 5 are examples of Ampère's efforts to highlight the phenomena he held to be of primary importance for a correct understanding of electrodynamics. As such, his diagrams and descriptions were suggestive construals of electrodynamic phenomena which Ampère then subjected to highly theoretical interpretation.