SummaryThe complex relation between molecular ideas and hydrodynamics in midnineteenth-century British science is considered. This relation is presented in the historical literature, almost invariably, in terms of a complete antithesis which signified an ontological commitment on behalf of British scientists to the idea that matter was essentially continuous. However, the analysis will reveal that molecular ideas were scattered within the main body of hydrodynamics and that molecular discourse was intersecting hydrodynamical discussions at specific points. Questions of resistance and complex fluid (...) phenomena were inviting various molecular conceptualizations of fluid matter, although these never took the form of a complete mathematical theory. (shrink)

Throughout his life J. J. Thomson was committed to a mechanical interpretation of nature. This work proceeded in several stages. Early in his career he attempted a Lagrangian formulation of mechanics. But due to certain epistemological difficulties with this approach, he began exploring various analogies and models, particularly those involving vortex motion. After his discovery of the electron in 1897, he commenced a synthesis of the electron with his previous physical conceptions. The result was a hypothesis of the ether as (...) being composed of particles even smaller than electrons. (shrink)

In the history of thermodynamics, two dates stand out as especially important: 1824, when Sadi Carnot's brilliant memoirRéflexions sur la puissance motrice du feuappeared in print; and 1850, when Rudolf Clausius published his similarly titled paper ‘Ueber die bewegende Kraft der Wärme’. In this paper Clausius narrowly beat the Scottish physicist William Thomson to the solution of a puzzle which had been highlighted in the latter's recent publications: how could Carnot's theory, with all its intellectual attractions, be reconciled with the (...) newly discovered principle of the inter-convertibility of heat and work? Clausius's solution (as is well known) was to replace Carnot's axiom of heat conservation, with the axiom now known as the second law of thermodynamics. (shrink)

SynopsisThe atomic theory of Dalton implied that there were more than 30 different kinds of matter, the chemical elements. William Prout (1815) was the first of a long line of distinguished speculators who sought to show, by argument and experiment, that this diversity overlay a more fundamental unity. Contrary to a common opinion, this was not an eccentric and unpopular movement, but involved many of the great names of nineteenth-century chemistry; and some of their speculations have proved to be very (...) near the mark. It may be that this strong current of well-informed speculation enabled the discoveries of cathode rays and of radioactivity (which provided the first real evidence of the complexity of the atom) to be integrated into the body of science with such remarkable rapidity. (shrink)