Sweetness and purity: The transverse flute

In the 19th century, flutes were made primarily of wood and metal; some, however, like this example, were made of glass. But whatever material is used, it is the vibrating air column that is the sounding medium. The material used naturally influences the thickness of the instrument wall, the shape of the sound wave, and often, the impression of the musician playing it.

Intensive research to improve the flute was carried out in the first half of the 19th century – at least regarding form and material. Instrument makers experimented with the position of finger holes, the internal bore of the body, and the mechanism. Their aims were a uniform and brilliant sound, a chromatic range with consistent intonation, more volume, and to some extent, better resistance to temperature and humidity. The most famous attempts and successes are attributed to Theobald Boehm, who introduced the ring key flute in 1832 and the cylindrical bore silver flute in 1847. But many others also experimented, not least of all with materials.

As early as 1806, Claude Laurent made and presented a highly unusual glass flute in Paris.[2] Laurent was not a flute maker, notably, but a machinist and watchmaker. As a material, glass posed new challenges, and combining it with a silver or nickel silver mechanism required new processing and joining technology.

In addition to the practical advantages of glass, namely its consistent intonation, resistance to humidity and insensitivity to temperature fluctuations, glass flutes reveal the instrument’s inner bore as well as the newly invented techniques for joining glass with silver applications.[3] These instruments are playable, but to a significant extent also have a representative character.

As for the tone of the glass flute, its clarity and purity are praiseworthy. With its material properties, it produces an especially sweet tone and is particularly easy to play. Dayton C. Miller, the US-American physicist, flute player and collector, wrote, “[...] the inventor has discovered that cristal (glass) is a proper material, as it gives sounds of the sweetness and purity desired, and also renders the tones invariable, and makes the instrument convenient and easy to play.”[4]

The options for processing glass certainly make a major contribution to the instrument’s characteristic sound. These include the wall thickness as well as the methods of polishing the inside and outside of the flute cylinder.

Three-part conical transverse flute with 4 keys, Inv. No. 58531

In addition to a glass flute by Laurent, the collection of the Deutsches Museum also includes a conical three-part transverse flute in D with 4 nickel silver keys (D#, F, G#, B♭) from around 1860; the manufacturer is not known. It is tuned to A435 Hz. Five fittings are made of nickel silver – an alloy of copper, nickel and zinc. The top of the head joint is closed above the embouchure hole by a fixed glass stopper.

The glass flute was recorded on July 30, 2018, in the former recording studio of the Deutsches Museum. To reduce the echo in the room as much as possible, the metal shelves were weighted down and the reverberation was measured. The reverberation time was about 250 ms. It was 28.3° C with 46% humidity. The colder a room is, the lower in pitch an instrument sounds. A dry room transports sound better.

For the sample library, Rüdiger Herrmann recorded single tones in different dynamics and performed three pieces as well. Two microphones were placed next to his ears; a third microphone was placed about 30 cm in front of him.

Playing the flute reveals its peculiarities: Some tones respond very well, and as one moves up the scale and goes higher, the tones become brighter and fluctuate more. However, the intonation of the flute is not ideal, especially in its fundamental key of D major; in the highest octave, only d, d#, e, f#, g, and a are playable.

For comparison, Rüdiger Herrmann played the same pieces in the same setting on a wooden flute in C (ebony/grenadilla) from his own collection. Dating from circa 1880, this instrument is a Meyer flute with ten keys (C'', B (short/long), G#, F (short/long), D#, C#, C, long D''' trill key) and a brass-lined head joint.

We think the wooden flute has much richer overtones and sounds much rounder than the glass flute; please listen and see if you agree.

Glass flute (Inv. No.: 58531)

Wooden flute in c, around 1880

Click here to play the glass flute.

For a material analysis of the flute, click here.

Citation: Rebecca Wolf, ‘Glass sounds or the fascination of transparency’, in: Materiality of Musical Instruments. A Virtual Exhibition.