During high summer 1721, while rioters and bankrupts gathered outside Parliament, Robert Walpole's new ministry forced through a bill to clear up the wreckage left by the stock-market crash, the South Sea Bubble, and the visionary projects swept away when it burst. In early August the President of the Royal Society Isaac Newton, a major investor in South Sea stock, and the Society's projectors, learned of a new commercial scheme promising apparently automatic profits, a project for a perpetual motion. Their (...) informants were a young Viennese courtier Joseph Emmanuel Fischer von Erlach, a contact of Desaguliers recently engaged in industrial espionage in northern England, and the Leiden physics professor Willem 'sGravesande, who had visited London five years earlier. They reported that they had been summoned to a remarkable series of demonstrations in the castle of Weissenstein, the seat of the Landgrave of Hesse-Kassel. In a carefully guarded room of the castle there was set up a hollow wooden wheel covered in oilcloth, about 12 feet in diameter and 18 inches thick on an axle 6 feet in length. Its designer, a Saxon engineer and clockmaker Johann Bessler, who travelled Germany under the name Orffyreus, had been in Kassel for four years, published schemes for perpetual motion and been appointed commercial councillor. The Landgrave, well-known as a patron of advanced engineering schemes, commissioned him to build a new machine and put it on show before expert witnesses (Figure 1). (shrink)

This article revisits the debate between Leibniz and Clarke to explore conceptual shifts in the use of the term medium. A basic tenet of physics since antiquity says that every act of communication ‐ that is, every transmission of a force from the place of its cause to that of its effect ‐ requires a medium to ensure its interaction. In the context of the Early Modern Period, media were regarded as mediating instances that enabled communication. If these instances were (...) not immediately connected but rather spatially separated from one another ‐ as in the case of gravitation, magnetism or electricity ‐ then there had to be a medium to ensure both the transmission of the force and the causal connection. Although the mediation of the medium took place in an inexplicable way, it seemed to explain one process or another by its mere introduction. The epistemological foundations of communicability ‐ those with which Leibniz, Clarke and Newton were attempting to come to terms ‐ remain relevant to the descriptive language with which we depict our present and its technological condition. Without duration there is no mediation but rather immediacy and simultaneity. Immediacy means that the necessary separation between the two events, the abyss of communication, is negated. Immediacies, like instantaneous actions at a distance, presuppose the difference they are deemed to eradicate. (shrink)

In the late 1810s and 1820s the Edinburgh phrenologists were largely concerned with trying to establish phrenology as the true science of mind. They challenged the accepted theories about the nature of mind and the brain; in turn, phrenology was attacked by the proponents of Scottish common-sense philosophy and by some medical men. The ensuing debate, which is discussed as an example of conflict between incommensurable world-views, involved a wide range of contentious theological, philosophical, scientific and methodological issues.

Euler’s ‘On the force of percussion and its true measure’, published in 1746, shows that not only had the issue of vis viva not been settled, but that the concepts of inertia and even force were still very much up for grabs. This paper details Euler’s treatment of the vis viva problem. Within those details we find differences between his physics and that of Newton, in particular the rejection of empty space and reduction of all forces to the operation of (...) inertia through contact. One can further see how Euler’s philosophy of science embraced explanation through mechanisms and equilibrium conditions.Keywords: Leonhard Euler; Vis viva; Equlibrium; Mechanics; Eighteenth century. (shrink)