Electric polyscope use to explore the larynx, 19th-century illustration. Here, an early type of endoscope is being used to examine a patient's throat and larynx. An electrical battery (right) is being used to power an electric light bulb that is mounted on a device to enable it to be used to examine the throat. The 'polyscope' was developed by French electrical engineer and inventor Gustave Trouve (1839-1902). Trouve's polyscope consisted of a battery developed by Gaston Plante, and a small incandescent airtight bulb. The caption at bottom is in French. Published in 'La Vie Normale et la Sante' (Normal Life and Health, Paris, 1881) by Dr Jules Rengade.