Seismology's acoustic debt: Robert Mallet, Chladni's figures, and the Victorian science of earthquakes.

In the nineteenth century, Ernst Chladni's acoustic figures provided productive new experimental techniques for investigating natural phenomena. The movement of invisible forces, such as light, electricity, magnetism, and heat, were hard for natural philosophers to examine. But Chladni's use of vibrating glass plates and sand to reveal the wave motions of sound offered an experimental framework through which to make natural phenomena visible. In Britain, it was Michael Faraday and Charles Wheatstone in the 1820s and 1830s who made best use of these practices and apparatus. Sound waves also provided new ways of thinking about earthquakes and seismic phenomena. This article explores how Robert Mallet, the first self-styled "seismologist", examined earthquakes, drawing on broader philosophical work surrounding vibrations and acoustic waves. Mallet was keen to draw parallels between the movement of seismic shock waves and the movement of musical sounds, including those from a piano moving through a room. He was not alone in this respect. Charles Darwin, among others, noticed comparisons between the sonorous and the seismic. By contextualising Victorian seismology within the context of Victorian acoustic science, this article argues that the two disciplines were deeply connected.