Summary This paper explores the legacy of the great French experimental physicist Victor Regnault through the example of Gabriel Lippmann, whose engagement with electrical standardization during the early 1880s was guided by Regnault's methodological precept to measure ‘directly’. Lippmann's education reveals that the theoretical practice of ‘direct’ measurement entailed eliminating extraneous physical effects through the experimental design, rather than, like physicists in Britain and Germany, making numerical ‘corrections’ to measured values. It also provides, paradoxically, exemplars of the qualitative theoretical practices (...) that sustained Regnault's misguided ambition to avoid theory. By considering the largely negative reactions to Lippmann's proposals for selecting suitable electrical units and methods of measuring the ohm, this paper associates these theoretical practices with the ineffectual rhetorical strategies employed by Lippmann to promote his work, and thereby indicates that the practice of direct measurement was limited to French experimental physics. Whilst this result aligns readily with the existence of divergent nineteenth century British and German cultures of precision, it emerges from a very different disciplinary context in which the practice of precision electrical measurement developed independently of submarine telegraphy. This is because, as this paper illustrates, telegraphic engineering and experimental physics remained separate professions in France. (shrink)

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Academic careers in French science during the mid-nineteenth century were made within the Université de France, an integrated state system of secondary and higher education controlled by a centralized Parisian educational administration. Among the most respected members of thecorps universitairewere Charles d'Almeida and Pierre Bertin, two historically obscurephysicienswhose significance derives from their substantial contributions to the social organization, teaching and communication of French experimental physics. This two-part comparative biography uses their entwined careers to make a case for the emergence of (...) a discipline of French experimental physics from the corps during the tumultuous politico-cultural transition from the Second Empire to the Third Republic. Of fundamental importance are disciplinary regimes of teaching and inspection within the corps, the foundation of the Société française de physique and theJournal de physique, and the diversification of the traditional pedagogical role of the Ecole normale supérieure, which, from around 1860, began to offer a career pathway for aspiring scientific researchers. Having established in this paper the socio-institutional mechanisms for the stabilization of a distinct field, in part two I characterize the epistemological–methodological aspects of French experimental physics. (shrink)

The late nineteenth century gradually witnessed a liberalization of the kinds of mathematical object and forms of mathematical reasoning permissible in physical argumentation. The construction of theories of units illustrates the slow and difficult spread of new “algebraic” modes of mathematical intelligibility, developed by leading mathematicians from the 1830s onwards, into elementary arithmetical pedagogy, experimental physics, and fields of physical practice like telegraphic engineering. A watershed event in this process was a clash that took place during 1878 between J. D. (...) Everett and James Thomson over the meaning and algebraic manipulation of dimensional formulae. This precipitated the emergence of rival “Maxwellian” and “Thomsonian” approaches towards interpreting and applying “dimensional” equations, which expressed the relationship between derived and fundamental units in an absolute system of measurement. What at first looks like a dispute over a seemingly esoteric mathematical tool for unit conversion turns out to concern Everett’s break with arithmetical algebra in the representation and manipulation of physical quantities. This move prompted a vigorous rebuttal from Thomsonian defenders of an orthodox “arithmetical empiricism” on epistemological, semantic, or pedagogical grounds. Their resistance in Victorian Britain to a shift in mathematical intelligibility is suggestive of the difficult birth of theoretical physics, in which the intermediate steps of a mathematical argument need have no direct physical meaning. (shrink)