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Incoming links: August Kundt
August Kundt 2026-10-18
A physicist whose appointments took him from Zürich in 1868 through Würzburg and Strasbourg to the Berlin chair of experimental physics in 1888.[ref]
August Kundt by Berlin-Brandenburgische Akademie der Wissenschaften. Kurzbiographie: physics professorships and life dates
Portrait of August Kundt
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Kundt's tube 2026-10-18
A Kundt's tube turns an invisible standing wave into a measurable spatial pattern. A driven air column supports a longitudinal wave; measuring its frequency and the spacing of repeated nodes of a standing wave gives the speed of sound. The same drive can compare the wavelengths in a gas and a vibrating solid. August Kundt's 1866 paper introduced acoustic dust figures; its footnote explicitly counts successive nodes of a standing wave as half a wavelength.[ref]
Ueber eine neue Art akustischer Staubfiguren und über die Anwendung derselben zur Bestimmung der Schallgeschwindigkeit in festen Körpern und Gasen by August Kundt. 1866 publisher record; original p. 502 footnote on half-wavelength spacing
The attractive feature is the separation of measurements: a clock or frequency counter measures repetition in time, while a ruler measures repetition in space. Their product supplies a propagation speed. The pressure pattern and the fluid-motion pattern are different, however; identifying which one a detector responds to prevents a quarter-wavelength mistake.