The Hipp Chronoscope.
The Hipp chronoscope is one of the most important scientific instruments of late 19th and early 20th century psychology. Following similar devices constructed by the English physicist Charles Wheatstone (1802 - 1875), the German clockmaker and mechanic Matthäus Hipp (1813 - 1893) presented his version of this electromagnetic precision timer in 1848. After Wilhelm Wundt (1832 - 1920) recommended the application of Hipp's chronoscope in the first edition of his path-breaking text book Grundzüge der physiologischen Psychologie in 1874, the "time viewer" was widely used in the emerging community of experimental psychologists.
Reference: Schraven, Thomas. 2004. The Hipp Chronoscope.. The Virtual Laboratory (ISSN 1866-4784), https://vlp.mpiwg-berlin.mpg.de/references?id=enc13