A selection of new arrivals September 2017 Rare and important books & manuscripts in science and medicine, by Christian Westergaard. Flæsketorvet 68 – 1711 København V – Denmark Cell: (+45)27628014 www.sophiararebooks.com AMPERE, Andre-Marie. Mémoire. INSCRIBED BY AMPÈRE TO FARADAY AMPÈRE, André-Marie. Mémoire sur l’action mutuelle d’un conducteur voltaïque et d’un aimant. Offprint from Nouveaux Mémoires de l’Académie royale des sciences et belles-lettres de Bruxelles, tome IV, 1827. Bound with 18 other pamphlets (listed below). [Colophon:] Brussels: Hayez, Imprimeur de l’Académie Royale, 1827. $38,000 4to (265 x 205 mm). Contemporary quarter-cloth and plain boards (very worn and broken, with most of the spine missing), entirely unrestored. Preserved in a custom cloth box. First edition of the very rare offprint, with the most desirable imaginable provenance: this copy is inscribed by Ampère to Michael Faraday. It thus links the two great founders of electromagnetism, following its discovery by Hans Christian Oersted (1777-1851) in April 1820. The discovery by Ampère (1775-1836), late in the same year, of the force acting between current-carrying conductors was followed a year later by Faraday’s (1791-1867) first great discovery, that of electromagnetic rotation, the first conversion of electrical into mechanical energy. This development was a challenge to Ampère’s mathematically formulated explanation of electromagnetism as a manifestation of currents of electrical fluids surrounding ‘electrodynamic’ molecules; indeed, Faraday directly criticised Ampère’s theory, preferring his own explanation in terms of ‘lines of force’ (which had to wait for James Clerk Maxwell (1831-79) for a precise mathematical formulation). Faraday’s criticism led Ampère to modify his theory, and to carry out his own experiments on electromagnetic rotation which actually went beyond what Faraday had accomplished. The present work, which AMPERE, Andre-Marie. Mémoire. “brought to a close his main sequence of research publications on electricity and and general insights should not suffice, for the explanation of the facts which magnetism” (Grattan-Guinness, p. 960), showed that Ampère’s theory was able comprise this new branch of Physics’. ‘The second is that by which I have given an to reproduce the results of the rival theories of Biot and Poisson. It immediately account of the observed phenomena’, where the magnet was treated as a solenoid. precedes Ampère’s summary work Théorie mathématique des phénomènes électro- ‘Finally the third hypothesis’, supported by Biot, assumed ‘a primitive elementary dynamiques uniquement déduite de l’expérience, which refers to it on p. 196: “je l’ai action’, in which magnet and pole tended to turn each other, thus ‘forming what d’ailleurs développée dans un autre écrit [the present work] où j’ai discutée même Mr. Poinsot has called a couple’; while for Ampère this was apparently ‘directly temps, sous ce nouveau point de vue, tout ce qui est relative à l’action mutuelle contrary to the first principles of Dynamics’, it needed examination. In order d’un aimant et d’un conducteur voltaïque.” This offprint is distinguished by the to further his comparison he presented again his surface-circuit theorem, and presence of the colophon ‘Bruxelles, M. Hayez, Imprimeur de l’Académie Royale’ related the expressions both to Poisson’s formula for magnetic action and to his at the foot of the last page of text, which is not present in the journal issue. The own for element/solenoid action. In the rest of the paper, he considered various present pamphlet volume is almost certainly from Faraday’s library (four of the cases of magnet/circuit action, noting all hypotheses but keeping his preference pamphlets in the volume are inscribed to him). It is also possible that the binding clearly evident” (Grattan-Guinness, p. 960). itself, which must be described as functional rather than decorative, was executed by Faraday: before becoming Humphry Davy’s (1778-1829) assistant in 1813, According to Ampère’s first theory of electrodynamic phenomena, magnetic the appointment which ignited his great scientific career, Faraday had been an forces were the result of the motion of two electric fluids; permanent magnets apprentice bookbinder. It is known that he bound his laboratory notebooks, and contained these currents running in circles concentric to the axis of the magnet some of his other books, himself (many are still held by The Royal Institution in and in a plane perpendicular to this axis. By implication, the earth also contained London). A volume of pamphlets such as ours would have been a prime candidate currents which gave rise to its magnetism. It was not long, however, before on which Faraday could exercise his old skills. Auguste Fresnel (1788-1827) pointed out to his friend Ampère that his theory had several difficulties, notably the fact that the supposed currents in magnets Provenance: Michael Faraday (inscription on title in Ampère’s hand: ‘à Monsieur should have a heating effect that was not observed. Fresnel suggested instead that Faraday de la Société Royale de Londres de la part de l’auteur’). the electric currents circulated around each molecule, rather than around the axis of the magnet. In January 1821 Ampère publicly accepted Fresnel’s idea. Between “[The] reconciliation of different physical models was of great importance to 1821 and 1822, Gaspard de la Rive (1770-1834), Albert van Beek (1787-1856) Ampère at this time … In a long paper on this matter presented to the Belgium and Faraday performed some experiments showing that the poles of a cylindrical Academy in October 1826 and published by them as [the present work], magnet are not located exactly at the extremities of the magnet, as was predicted he extended the discussion into a general appraisal of three hypotheses for by Ampère’s theory. These experiments forced Ampère to modify his conception electromagnetism. ‘The first consists in admitting the existence of two fluids of microscopic currents: due to the collective interactions between the small called austral and boreal’, as thought Poisson (for example); ‘But some vague current-carrying loops, the planes of these molecular currents should, he said, no AMPERE, Andre-Marie. Mémoire. longer remain perpendicular to its magnetic axis. For both Jean-Baptiste Biot (1774-1862) and Siméon Denis Poisson (1781- 1840), on the other hand, electrical phenomena were to be explained in terms of magnetism, not the other way round. Together with a protégé, Félix Savart (1791-1841), Biot performed experiments late in 1820 which led them to the ‘Biot-Savart law’ for the force exerted on a magnet by a current-carrying wire. Biot claimed to have deduced this law from “a mathematical expression for forces assumed to act upon magnetic fluid particles from each tiny section of a conducting wire, [but] Biot considered this conclusion to be only a preliminary step toward a full explanation based on an understanding of ‘a true molecular magnetization impressed upon the particles of metallic bodies by the voltaic current that traverses them.’ For Biot, the genuine fundamental forces were assumed to act between magnetic fluid particles in the wire and in the magnet” (Hofmann, p. 234). “Biot claimed that the central issue to be resolved was ‘how each infinitely small molecule of the connecting wire contributes to the total action of the section to which it belongs’ and thereby brings about the ‘molecular magnetism’ of the wire … From Biot’s point of view, explanation of all the new phenomena ultimately had to be traced to a specific distribution of magnetic fluid particles” (ibid., p. 281). “Biot’s Laplacian colleague Poisson took an even more conservative approach. Rather than try to account for the new electromagnetic and electrodynamic phenomena, he developed a purely magnetic theory in strict accordance with Laplacian standards. In parallel with his two electricity memoirs of a decade earlier, during 1824 Poisson developed an analogous imponderable fluid theory of magnetism in two lengthy memoirs he eventually published in 1826. Unimpressed by developments inspired by Oersted’s discovery in 1820, Poisson staunchly preserved the Laplacian tradition by treating magnetism as a domain entirely distinct from that of electricity. With a single introductory remark, he cavalierly AMPERE, Andre-Marie. Mémoire. dismissed the issue that so preoccupied Ampère. ‘The identity of the magnetic identical to that which a conducting wire would exert on the same molecule if it fluid and the electric fluid does not necessarily result from the important facts was substituted for the closed contour which circumscribes this surface. It is in that have been discovered recently. Fortunately, the solution of this question is this way that one accounts for this law in the first hypothesis in which everything not at all relevant to the object of this memoir; our analysis is independent of the should be reduced to the mutual action of austral and boreal magnetic molecules” particular nature of the boreal and austral fluids; our goal is simply to determine [p. 21 of the present work]. the resultants of their attractions and repulsions, and, if it is possible, how they are distributed within magnetized bodies’ … [Poisson’s] most fundamental physical “Ampère’s own view was of course that electromagnetic interactions are all due assumption was that magnetic effects are produced by two magnetic fluids that to more basic interactions between electric currents. Nevertheless, by showing act on each other through fundamental forces that vary as the inverse square that the Biot-Savart force could be reduced to interactions between magnetic of the distance between their particles. Poisson also assumed that the austral elements, Ampère could argue that there was no need to follow Biot and postulate and boreal fluids are confined by some unknown force to the interior of small a transverse force between current elements and magnetic molecules; he then ‘magnetic elements’” (ibid., pp.