'An attempt to trace illusions to their physical causes': atmospheric mirages and the performance of their demystification in the 1820s and 1830s.

This article suggests that, during the 1820s and 1830s, Britain experienced a mirage moment. A greater volume of material was published on the mirage in scientific journals, treatises, travel literature and novels during these two decades than had occurred before in British history. The phenomenon was examined at the confluence of discussions about the cultural importance of illusions, the nature of the eye and the imperial project to investigate the extra-European natural world. Explanations of the mirage were put forward by such scientists and explorers as Sir David Brewster, William Wollaston and General Sir James Abbott. Their demystification paralleled the performance of unmasking scientific and magical secrets in the gallery shows of London during the period. The practice of seeing involved in viewing unfathomable phenomena whilst simultaneously considering their rational basis underwrote these different circumstances. I use this unusual mode of visuality to explore the ways the mirage and other illusions were viewed and understood in the 1820s and 1830s. Ultimately, this paper argues that the mirage exhibited the fallibility of the eyes as a tool for veridical perception in a marvellous and striking way, with consequences for the perceived trustworthiness of ocular knowledge in the period.