In 1999, Chris Cree Brown designed an Aeolian Harp within a sculpture that would assist the wind flow across the strings and provide a suitable resonant space in which people could enjoy the sounds. In 2000, he constructed a 40% working model for display in the Christchurch Botanical Gardens as part of the Scape : New Zealand Community trust Art + Industry Urban Arts Biennial 2002.
I have been enthralled by these magical instruments for twenty-five years. The variety of sounds generated by these enchanting instruments is astounding – sometimes quiet, mysterious and ethereal, sometimes dazzling, virtuosic and strident. As these 6-12 stringed instruments are played by the wind, the beautiful envelopes of sound seem composed by Gaia herself, and never have a sense of being contrived. The word ‘Aeolian’ is derived from Aeolius, the Greek God of wind.
The History of the Aeolian Harp
There is evidence that the Ancient Greeks hung many Aeolian harps in their ancient cities, making use of the uniform breezes as they came off the Mediterranean Sea.
The mythical origins of the instrument is said to have resulted from a dead sheep being left on a post: the intestines and sinews dried, stretched and acting as strings while the bones and skin of the torso formed a crude resonating chamber. These dead sheep began to emit ghost-like sounds. (A Turkish version is similar, but involves a dead turtle being washed up on the shore).
In the Middle Ages several people were burnt at the stake for witchcraft as a result of making these magical instruments which played by themselves!
In Victorian times, Aeolian Harps were fashionable and designed to fit into double hung windows. There are many literary references to Aeolian Harps in this era.
One of the more fascinating references is from Louis Hector Berlioz (1803-69) in his Voyage musical en Allemagne et Italie (1844).
“….. listen to the fantastic sound of the Aeolian Harp hung from the top of a tree stripped of it’s leaves, and I defy you not to experience a deep feeling of sadness, of surrender, a vague and boundless yearning for another existence, and immense loathing for this one; in a word, a sharp attack of the spleen linked to a temptation toward suicide.”
The Design and construction of the Aeolian Harp
Traditionally, all the strings are tuned to the same pitch, but are of different diameters. I have tried several different tunings (including whole tone scales and random tunings) which provide a wide range of sounds with different characters. Even with similar tunings, the sounds vary widely depending on the wind direction and strength , air pressure and other variables. For the harp in the Christchurch botanical gardens, I use a 10 stringed instrument, that has 6 strings tuned to the same pitch (around an F), 2 strings tuned to the major third higher and 2 strings tuned to a perfect 5th higher.
Information on the design and construction of Aeolian Harps is scanty at best, and often misleading or erroneous. However, through a series of (unsystematic) trial and error experiments over the last twenty-five years, I have made incremental improvements in the efficiency of sound production. The more recent constructions embody several unique innovations such as bridges that allow the strings to lie perpendicular to the soundboard as opposed to strings that are parallel to the soundboard.
The Physics and Acoustics of the Harp
While the physics and acoustics of these instruments are rather complex, they often seem to me to be as eloquent and beautiful as the sounds themselves.
One of the fascinating formulas to predict an Aeolian tone is:
fo = cV/d
where c = a constant (a dimensionless number known as the Stroual number,
which is usually around.2, but varies slightly with
airpressure and other variables)
V= the velocity of the wind
D = the diameter of the string.
Thus a .6 mm diameter string in a wind with a velocity of 1.5 metre per hour, the pitch will be
(.2 )x 1.5/ . 0006 = 500 hz or just above the B above middle C)
Since this formula makes no mention of either the tension or the length of the string, these parameters do not have any influence on the pitch emitted. If a string is emitting a pitch and the string is lengthened, it will have a lower fundamental, but will yield a higher harmonic of that lower fundamental. Similarly, if the string is tightened, the fundamental will be higher, but will yield a lower harmonic of that higher fundamental.
The Design and Construction of a large structure to house an Aeolian Harp
A design for a structure to house an Aeolian Harp should take account of the following important elements:
i ) A design that would collect the wind and send a laminated flow of air onto the strings
ii) A design that would reflect the sound to a central point where the public could hear and enjoy the sounds
iii) the design should preferably limit the amount of extraneous sound (traffic, leaves rustling, other voices).
The shape of the sculpture is symmetrical about its latitudinal and longitudinal axis and incorporates three different elliptical curves creating a resonant chamber that is as efficient as possible, (with all the sound being directed or redirected to the centre of the chamber).
The material of the structure is concrete since this material works well as a reflector of sound.
The central wall creates a bottle-neck effect where the wind is forced through the gap which contains the harp. As long as the pressure on one of the openings is different from the other, and the area of the openings is substantially greater than the gap in the wall, air will be forced through the gap and thus activate the strings.
I have designed several permanent site-specific musical sculptures that embody an Aeolian Harp, the first in 1983 for the Wellington Waterfront. Perhaps it is not surprising that these designs have never gone beyond the drawing board: the cost of a structure for any large permanent musical sculpture would be substantial, and it would be unlikely that either the local authorities or any financial backer would agree to support such a large scale musical sculpture no matter how enthusiastic and committed the designer. It would be seen as a complete unknown and a potential white elephant.
As a result, it seemed perspicacious to build a working model and exhibit it in order to gain the necessary support.
Over a period of two years, I designed and constructed a 40% working model of the above structure, and tested it on a hill at a farm near Darfield. I was elated by the beauty of the first few sounds, but over the course of a year, I was able to significantly improve the sound. The resonant chamber(s) seemed to substantially amplify the sound, (although in reality, it is more a matter of containing the sound).
From September through to November of 2002, the harp was exhibited it in the Christchurch Botanical Gardens as part of the Art and Industry biennale.
I chose to mount the model on a plinth for the following reasons:
1) the plinth conveys the idea of the sculpture as a model.
2) the plinth adds to the volume of the structure and means that there is a bigger object for the wind to find a path through. (Also, in sheltered places such as the Christchurch Botanical Gardens, there is substantially more wind a few feet above the ground than at ground level).
3) the plinth means it is more difficult for the public to reach the delicate parts of the harp itself.
4) without the plinth, the public would have to bend down to hear the harp speak.
I have been elated with the success of the project and the response from the public. The site has proved to be near perfect. My fear that the surrounding foliage might inhibit the wind flow was unfounded; indeed the foliage acts to ameliorate the stronger gusts of wind (particularly from the North west quarter).
In some ways, I feel that as a composer, this is the first project where I have had some real communication with the community. In other ways however, I often feel that it is not me doing the communicating: rather it is Gaia or some undefined sentient energy which embodies the earth. All I have done is simply construct a device that ‘unlocks’ these sounds. This is why the sounds to me have such a magical, even spiritual quality. (See the quote from Hector Berlioz above).
The music (and even the idea) of the Aeolian Harp seems in many ways to be the antithesis of a world that appears increasingly brutal in a psychological sense. The harp seems to have the ability to transcend the often perplexing and seemingly irresolvable problems of our world and transport the individual to a quiet, personal, serene, and supernatural world.
There is no doubt that many people are deeply affected by the charm of the harp and its music. To me, both the sounds of the harp and the instrument itself seem to have a cognisant persona that has lead me on a spell-binding journey for the last twenty-five years. Notwithstanding that the musical sculpture is a 40% model, it has given me some contentment to finally have the beauty of this instrument and its intricate web of sounds on public display.
The Aeolian Harp is a very special project, and of course, my hope is that the model will inspire the local government, the public and financial backers to support
Chris Cree Brown