WHY DID PEOPLE talk of ‘balloon madness’? What did they mean by it? The language around balloons after 1783 indicated their effect was startling. ‘Balloon madness’, a phrase widely used in the first two years of aerostation, has simple and deep meanings. Superficially, ‘madness’ refers to an abnormal, unstable cultural phenomenon, like the use of the word ‘craze’ in the twentieth century to describe mass enthusiasm for something. Close to ‘craziness’, the term ‘craze’ signals that a significant number of people is affected, and lightly pathologises their obsessiveness in terms of mental disorder. Madness and craziness involve disturbing ways of behaving. In the 1780s, this language of disturbance had resonances that came from deep-running ideas. ‘Balloon madness’ drew on at least four currents of thought that flowed together in intricate ways from medicine, politics, religion and fashion; each had a way of explaining how ideas caught on and spread. The force of the term ‘balloon madness’ in the 1780s came from a confluence that held an easy position in everyday language but was all the more powerful for being continuously fed by explanations also themselves evolving. ‘Madness’ seems obvious, and we still use it obviously to describe what we disagree with. What it meant in the 1780s also had a hinterland of ideas not all familiar to us now.

The pathology of madness had a large literature in the late eighteenth century. As Enlightenment medicine moved on from old models of imbalance of humours accounting for illness, it kept a sense of aggression as relevant. So do we: wounds can still be described as angry. A key term, ‘rage’, described how epidemics spread. In 1782 the sentimental novelist Henry Mackenzie wrote to the economist Adam Smith hoping he had escaped ‘the Influenza, which has raged in London and now begins to rage here’. Disease raged through bodies: in 1784 a treatise on farriery discussed the staggers ‘that rage so furious and fatal among Horses at this present Time’.