The 120-Year-Old Mind-Reading Machine
Once recorded sound became reality, people believed all kinds of things were possible.
In the 1890s, when telephones and automobiles and lightbulbs were still strange and wonderful, inventors promised another remarkable device would soon be ubiquitous: the mind-reading machine. Inspired by the phonoautograph—a new device that showed what sound waves looked like on paper—the scientist Julius Emmner invented a machine that he said could record thoughts. It was simple, really. If invisible sound vibrated in a ways that could be measured, Emmner figured, why wouldn't unseen thoughts do the same?
“Sound is addressed to the ear,” of Washington, D.C., in August 1895, “yet
