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.
Object, Instrument, Technology

This apparatus consists of three wires, each bent to resemble transverse waves. The wires are mounted in a rectangular brass box that was placed in front of the lens of a projector. The top two wires are identical, but positioned so that their shadows appear to move in opposite directions as a crank on the side of the box is turned. As they do this, the crests and troughs of the waves alternately lineup and overlap. The corresponding “interference” of the two waves is seen in the changing shape of the third wire.

Object, Instrument, Technology

André Prosper Crova was a faculty member at the University of Montpelier. He invented this acoustic wave model in the 1860s and commissioned the prominent Parisian acoustic instrument maker Rudolph Koenig to manufacture it for him. It was first shown at the 1867 Paris World Fair.

Object, Instrument, Technology

„This instrument was used in an Ohio high school and probably dates from the late 19th or early 20th centuries. The replication of classic experiments was a common way to teach science at this time, and Chladni’s figures were considered to be both instructive and beautiful. 

Object, Instrument, Technology

These instruments demonstrate the “communication of vibrations” between connected plates. This was a topic first investigated by the French scientist Felix Savart, in the 1820s. Savart experimented with a pair of identical glass disks that were connected by only a single glass rod. When the two disks were sprinkled with sand and the first one vibrated, both disks formed identical patterns.

 

 

Source: Steven Turner; Curator, Physical Sciences, National Museum of American History, Smithsonian Institution. 

Picture: Steven Turner

Object, Instrument, Technology

This rack has 3 square and 3 circular brass plates of varying dimensions. It was used to demonstrate the effect of changes in the size and thickness of plates on both their tone and the Chladni figures that they produce. A plate that is the same size as the one next to it, but double the thickness, will produce a note twice as high, while a plate that is half the area of the one next to it, but double the thickness, will sound a note that is four times higher.

 

 

Object, Instrument, Technology

See also Helmholtz resonator

Picture: Max Planck Institute for the History of Science

Object, Instrument, Technology

This is a set of 16 Helmholtz resonators. Made from sections of brass that were spun on a lathe, they are wonderfully light and easy to hold. Helmholtz designed them to demonstrate his theory that all vowel and musical sounds are composed of combinations of simple, pure notes (Helmholtz’s “Theory of Timbre”). He correctly observed that musical sounds, particularly the higher tones, are often perceived as a single mass of sound.