This post presents a collection of old engravings of acoustical apparatus. I first ran into these many years ago when I was editing the Experimental Musical Instruments quarterly journal. A few different readers wrote in at various times to mention the existence of these wonderful old illustrations and suggest that we reprint some of them in the pages of the journal.  That we eventually did, in Vol  11 #4, June 1996.  I’ve loved engravings of this sort ever since. A while back I suggested to David Samas that we should put together an exhibit of a selection of them.  David is my co-curator at the Window Gallery in San Francisco’s Center for New Music, an exhibit space devoted to the display of new musical instruments and sound sculpture. The show went up in 2016, with David as the official curator and me as the unofficial finder and selector of pictures, and for the next couple of months these images tickled the fancies of people passing in and out of the Center.  The pictures in this post are the same ones that appeared in that show. Special thanks go to both David and Ian Saxton for creating the clearest and cleanest possible digital copies of the images.

The illustrations in this collection are depictions of apparatus created in the late 19th century for experimentation and demonstrations in musical acoustics. Prior to the advent of oscilloscopes and other electronic sound-analysis tools, even seemingly rudimentary tasks of acoustic analysis – determining the frequency of a musical tone, for instance, or making waveforms observable – were not simple jobs  with obvious solutions.  It fell to researchers of the time to come up with mechanical devices, often quite clever and sometimes rather complex, to make these investigations possible.

Far and away the most accomplished among makers of such devices was Rodulf Koenig, operating out of a workshop in Paris between 1858 and 1901. Other important makers, designers or commissioners included Jules-Antoine Lissajous, Édouard-Léon Scott, E. Mercadier,  Félix Savart, and Ernst Chladni.

During this era, several books on musical acoustics appeared containing woodcuts of such devices. Illustrations originally appearing in catalogs from the Koenig workshop are the source for many of the pictures in these books, but not all.  And who created these often exquisite illustrations? It seems a crime, but the artists are rarely credited in the original publications. A couple of names do come down to us, though: several of the illustrations in the Koenig catalogs are signed Ch. Berger, and several more with the single name Perot.

The images appearing below are selections from the Koenig catalogs and other contemporaneous published sources.  If you want to explore beyond these selections, a good starting place would be this reproduction of the 1889 catalog of the Rudolf Koenig workshop, courtesy of the Smithsonian Institution.



1. Tuning forks with attached air chamber resonators.  The weights on one of the forks are for fine-tuning. These are part of a much larger set of carefully tuned forks together comprising Koenig’s “Grand Unified Tonometer,” designed to be used as an all-purpose tuning reference.

Fronticepiece from J. A. Zahm’s Sound and Music, 1892.





2. Double siren designed by Hermann von Helmholtz and constructed by Sauerwald in Berlin.  In sirens, a rotating disk is perforated with rings of holes which alternately block the passage of compressed air or allow it though in rapid series of puffs at an audible frequency.  This dual siren allows for a variety of acoustic explorations relating to acoustic interference patterns.

From Hermann Helmholtz’ On the Sensations of Tone, 1877. .




3. Wave Siren.  In this device, wind from a compressed air source passes through one or more of the fifteen tubes and out through nozzles at the tube ends.  The nozzles are positioned extremely close to, and pointed at, the wavy rims of the rotating disks.  The undulations in the rim of the disk variably block and unblock the airflow as they pass, creating audible waveforms analogous to the wavy rim shapes.

From Catalogue des Appareils d’Acoustique Contruits par Rudolf Koenig, 1889. Also appears in J.A. Zahm’s Sound and Music (1892) as well as other publications.




4. Wave Siren. Though oriented differently, this is similar to the other wave siren shown in this collection, but with more complex wave forms in the undulating rims. In addition, it has a disk siren at the top with four air nozzles.

From Catalogue des Appareils d’Acoustique Contruits par Rudolf Koenig, 1889.




5. Scott’s Phonautograph.  In this device, sound gathered at the open front end of the large horn is directed to a small membrane at the rear. A stylus is attached to the back of the membrane, just touching the surface of the rotating drum behind.  When sound waves agitate the membrane, the stylus moves, scribing a visible trace on smoked paper placed over the surface of the drum as the drum rotates.  It thus creates a visible record of the soundwave pattern.  Devices of this sort were first created by Édouard-Léon Scott, and later copied by various makers.  This drawing appears to be based on Koenig’s version of the device, but is not the drawing from the Koenig catalog.

From Catalogue des Appareils d’Acoustique Contruits par Rudolf Koenig, 1889.Also appears in Franz Josef Pisko’s Die neueren apparate der akustik (1865).


6. Duhamel’s Vibroscope, named for the French mathematician and physicist Jean-Marie Constant Duhamel.  Like Scott’s Phonautograph (but simpler), the vibroscope is a scribing device, in this case recording the movement of a tuning fork tine.  Woodcuts depicting such devices appeared in several sources during this time period.  Most of them are not as fanciful as this, typically showing tuning forks of normal size. Some show more elaborate versions of the idea employing mechanical methods for scribing the combined wave form of two differently tuned forks.

Source unknown; reprinted in Anna Giatti & Mara Miniati’s Acoustics and Its Instruments: The Collection of the Istituto Tecnico Toscano, 2001.


7. Forks and Mirrors.  Jules-Antoine Lissajous popularized the idea of placing a mirror at the end of a tuning fork tine with a counterbalancing weight on the opposite tine. A strongly focused light is directed at the mirror and reflected onto a screen. If the fork is then slowly rotated, then the point of reflected light traces an observable wave on the screen. (The effect depends on retinal persistence in the viewer’s eye).   As this drawing shows, more complex interactions can be displayed through the use of two mirrored forks.

From Pietro Blaserna’s Theory of Sound in its Relation to Music, 1883.


8. Early Additive Syntheses Machine. Helmholtz was one of the first to explore the idea that musical timbres as well as human vowel sounds could be analyzed by their overtone content.  He used a machine like the one shown here to synthetically recreate such sounds. To provide sustain and avoid the distraction of a sharp attack, the machine used tuning forks activated electromagnetically. This was done using a clever system to generate the desired AC frequency for the electromagnetic drivers using another tuning fork as the original oscillator. This fork was set up so that when vibrating it alternately dunked and un-dunked an electrical wire in a conducting solution of mercury and alcohol.

This drawing is from Franz Josef Pisko’s Die neueren apparate der akustik  (1865). In the Koenig catalog can be found a less entertaining but more refined image depicting a better-made version of the apparatus.    


9. Manometric Flame Interference Apparatus. This device employs eight air-chamber resonators tuned to the harmonic series of a single fundamental.  Associated with each resonator is a gas tube which feeds a small flame. Through a clever configuration, a sensitive rubber membrane at the back of the resonator controls the flow of gas in the tube. If a nearby sound contains the resonator’s natural frequency, the air resonance is excited, thus modulating the flow of gas and causing the flame to rise and fall in agreement. The flame’s motions are too rapid to analyze through direct observation, and this is where the hand-cranked, tilted column on the right comes in. Each of its four surfaces is a mirror, and by rotating the column at the right speed, a stroboscopic effect is created. Controlling rotation speed, the observer can freeze or slow the flame vibration patterns as they appear in the rapidly turning mirrors. Watching the behavior of the eight flames, the observer can analyze the overtone content of a tone with the given fundamental.

From Pietro Blaserna’s Theory of Sound in its Relation to Music, (1883). This image is based on a similar, but not quite identical one appearing in the Koenig catalog.  (The Blaserna version was chosen for display here because it’s a bit clearer.)


10. Compound Pendulum.  In this device, the combined motions of two pendulums are communicated to a stylus which scratches the resulting patterns on a smoke-blackened sheet of glass.  Through a lamp-and-mirror arrangement, the resulting image can be projected onto a screen.  Through weights on the pendulums their periods can be adjusted, creating various frequency relationships between the two and producing images reflecting the chosen harmonic relationships. The results are analogous to sound wave patterns, even though the pendulum frequencies are well below the audible range.

From J.A. Zahm’s Sound and Music (1892).





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