The kymograph could create visual representations of measurements carried out over a certain period of time, and played an important role in physiology, acoustics, and other areas. Invented by Carl Ludwig in 1847, kymographs were produced for many years and commonly used until at least the 1920s. In a kymograph, the writing surface is inscribed by a stylus whose movements correspond to changes in the measured value. The writing surface is attached to a rotating drum that moves it past the stylus, creating a two-dimensional representation out of the stylus’s one-dimensional movements. This general principle of time-based inscription was an important prerequisite for the development of sound-reproducing media, most notably the Edison phonograph.

Picture showing the use of the kymograph in a physiological laboratory, from: Angelo Mosso, L’Institut Physiologique de l’Université de Turin, 1894: 26

Collection of illustrations showing different models and modifications of the kymograph

Kymograph as part of an experimental setting, on display in the Science Museum, London