Object, Instrument, Technology

The vibration microscope is an electromagnetically-driven adaptation by Hermann von Helmholtz (1821-1894) of the earlier optical comparator by Jules Antoine Lissajous (1822-1880). The device allows one to determine the frequency of a tuning fork or other vibrating object with respect to a fork of known frequency, by way of Lissajous figure analysis.

Video
Braguinski, Nikita. 2018. Brüel & Kjær 2304 Level Recorder (Video).
Object, Instrument, Technology

The Case Collection of Physics Instruments (CCPI) has several dozen forks mounted on resonance boxes (see Fig. 1).

Object, Instrument, Technology

Date of production: 1950s

Image
“Brüel & Kjær 2304 Level Recorder (1)”. n.d.
Image
“Brüel & Kjær 2304 Level Recorder (2)”. n.d.
Video
Chladni, Ernst Florens Friedrich. 2012. “Chladni Plate Demonstration From The National Museum Of American History”. Smithsonian National Museum of American History. https://youtu.be/KEttRmu2kGk.
Text
Koenig, Rudolph. 1864. “Beirag Zur “Theorie Der Klangfiguren Von Wheatstone””. Annalen Der Physik Und Chemie 122: 238-242.
Object, Instrument, Technology

The German scientist Ernst Chladni was one of the pioneers of experimental acoustics. His research on different kinds of vibrations served as the basis for the scientific understanding of sound that later emerged in the 19th century. 

Object, Instrument, Technology

In its simplest form the siren consists of two metal disks, each having the same number of regularly spaced concentric holes. The lower disk is mounted on the base of the siren, while the upper disk is mounted on a steel shaft just above it. As air is forced through the system, the upper disk begins to rotate. As it spins, the holes in the two disks briefly line up and then quickly close. Each time they do this, a brief puff of air is released. Each of these puffs acts like a single sound wave, and if enough of them are produced we perceive them as a continuous musical sound.