A 16-foot musical bow

Musical bows are found in varying forms in many parts of the world and their origins probably date well back into pre-history. It is possible they were among the earliest musical instruments created by humans. Bows can be either rhythmic or melodic instruments - the Afro-Brazilian berimbau and Indian malunga are essentially rhythm instruments whereas the Appalachian mouthbow can be used to play melody lines. Generally musical bows are rather smaller than this one - most are close in length to the type of bows used as weapons.

This project came about because a long straight branch came off a holly tree in my garden. I was already fascinated by one-string musical instruments and so the idea of a giant musical bow seemed obvious. The size was determined by the length of the branch.

The basic arrangement is based on the berimbau, an instrument associated with the combination of martial art and dance known as capoeira. It is played by drumming on the string with a stick, a bit like a berimbau. However I have deliberately not called this a giant berimbau because its size forces differences in playing technique. In some ways it is closer to certain of the instruments used by Grateful dead drummers Bill Kreutzmann and Mickey Hart in creating atmospheric music for the film Apocalypse Now. See what you think by listening to the samples further down this page...

(Clicking on the pictures below will lead you to larger, higher resolution versions)

A bow on its own does not produce much audible sound, so most musical bows incorporate some type of resonator - often a hollowed gourd or similar. As it happened, I had an old incinerator which was no longer useful because its bottom had rusted through. This seemed ideal. The orange thing in the picture is an axle stand - it isn't a vital part of the design.

To connect the resonator (incinerator) to the string I used an arrangement based on a berimbau. In that instrument, the steel string (the "arame") is connected to the gourd resonator (the "cabaça") by a loop of string known as the "anel". In the giant bow, the string is linked to the resonator by a loop of wire that passes around a convenient handle on the incinerator lid.(See note 1)

This forms a type of bridge, dividing the string into a long section and a short one. Two different ranges of sounds are produced by striking the string on different sides of the bridge. The bridge is not fixed and its position can be changed to divide the string in differing proportions if desired.

In addition to varying the tone by striking the string in different places a small variation in pitch can be achieved by pressing on the bow with one hand while playing. The following MP3 samples demonstrate this:

• Tones made with the shorter section of string - click here
• Tones made with the longer section of string - click here

The string I used is medium gauge galvanised wire bought at a garden centre. At one end of the bow the string is secured with an old hub bolt for a bicycle (The end of the wire was formed into a loop and fed into a slot sawn into the end of the bow. The bolt passed through the loop and, when tightened, squeezes the string in the slot).

I initially hoped it would be possible to simply use the above style of fixing at both ends. I thought it would be possible to adjust the instrument by wedging something under one end of the string, as is often done with crude diddley bows. However the galvanised wire quickly showed a tendency to stretch and become slack. I addressed this by taking one of the tuners off an old bass guitar and fitting it to the bow as shown in the next two pictures.

This serves multiple purposes: as well as allowing a degree of moderately accurate tuning and providing adjustment to compensate for string stretch, it also makes stringing the instrument a lot easier.

Finally, a quick illustration of how I recorded the sounds - the air holes in the incinerator proved convenient for placement of the microphone from my PC. For the future I am thinking about fitting a piezo transducer somewhere.

Notes:

(1) This arrangement was significantly louder than an earlier arrangement that had the loop passing around just the string and the wooden part of the bow at the point where the bow rested on the incinerator chimney.