The concept of electrical conductivity, or, as initially coined by Stephen Gray , ‘electrical communication’, has always been assigned an important role in the history of electrical research. Some thirty-five years after Gray's ‘electrical communication’ acquired wide attention, Priestley employed the concept of conductivity to define physical reality, thus giving a privileged position to the science he himself endeavoured to cultivate. As he argued in the introduction to The History and Present State of Electricity , ‘the electrical fluid is no (...) local, or occasional agent in the theatre of the world. Late discoveries show that its presence and effects are every where … It is not, like magnetism, confined to one kind of bodies, but every thing we know is a conductor or nonconductor of electricity’. Contemporary historians, for example, Heilbron, Home and Hackmann, link the concept of conductivity to a radical transformation of electrical research which pertained to its mode of organization and the definition of its subject-matter, and which culminated in its emergence as a distinctive branch of eighteenth-century ‘experimental philosophy’. (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)