Carl Ludwig's Invents the Kymograph, the First Scientific Instrument to Record Scientific Information in Real Time

In 1847 German physician and physiologist Carl Friedrich Wilhem Ludwig published "Beiträge zur Kenntniss des Einflusses der Respirationsbewegungen auf den Blutlauf im Aortensysteme" in Archiv für Anatomie, Physiologie und wissenschaftliche Medizin (1847) 242-302 issued from Berlin.

This was the Ludwig's first description of his kymograph, the first instrument to record scientific information in graphic form in real time, which Ludwig created by modifying Poiseuille’s hemodynamometer so that it could record its results graphically. This device, further modified by Marey and Chaveau, became a standard tool for the graphic recording of experimental results; it is illustrated in Ludwig's plate numbered 10 in the journal volume. 

Ludwig's paper was accompanied by 5 plates showing the apparatus and its method of graphic recording on a metal drum covered with smoked paper which was scratched with a moving stylus, leaving smoke-free lines. These paper sheets were then removed from the drum and fixed with varnish to preserve the record.