Historical instruments are an important part of our cultural heritage, and scientific examination can help us to determine lost details about how the instruments were manufactured, and when, and provide us with important information to assist with their conservation.
When dealing with irreplaceable cultural artifacts, it is important that any testing methods are non-destructive, and that the artifacts themselves are not left unavailable for long periods of time due to lingering radioactivity. A chapter in Neutron Methods for Archaeology and Cultural Heritage1 explores the ways in which neutron studies can help us to uncover the secrets of our musical heritage.
Dr Giulia Festa is an author on the chapter. She says, “Most musical instruments are complex objects, made from more than one material. Discovering more about their designs and their material composition helps us to understand the original method of manufacture, and can aid in the reconstruction of missing parts.” X-ray imaging is well-established as a non-invasive technique for examining wooden and leather objects, but X-rays are strongly blocked by metals. In contrast, metals are transparent to neutrons, which are strongly attenuated by wooden areas.
Dr Festa says, “A combination of both neutron and X-ray imaging provides a full overview of the instrument, including its internal features, and is therefore considered to be best practice.”
For the case studies featured in the book, investigations were carried out using ISIS’ INES instrument and the NEUTRA beamline at the spallation neutron source SINQ in Switzerland. Neutron diffraction is a powerful technique for investigating the crystal structure of samples; Neutron imaging (Radiography and Tomography) creates 3D images of the internal structure; and Neutron Resonance Capture Analysis produces spectra directly related to the instrument’s isotope content.
One case study examined the internal structure of a collection of seven woodwind instruments, manufactured in the 16th or 17th century. The internal features of the bore hole of an instrument are important clues as the methods of manufacture, and play a fundamental role in the quality of the sound produced. Small adjustments to the shape of the bore hole are made by hand during construction, to produce the desired sound. Neutron and X-ray radiographies of two of the instruments showed slight tapering of the bore hole, a manufacturing style that dates them to the Baroque period.
Another case study examined a metallic flute, made by Charles Mathieu in 19th century Paris. There is little historical information to accompany this flute, which was manufactured from a laminated sheet of metal, curved and soldered down the back. The mouthpiece is visibly different, probably made using a mould. At some point during its recent history, this unfortunate instrument was broken in two, and required restoration.
Neutron diffraction shows that the mouthpiece is made from lead, with a low percentage of antimony added to strengthen the metal. The instrument is zinc covered with a palladium layer, soldered together using a lead/tin alloy.
The new IMAT instrument at ISIS opens new opportunities for research on musical instruments. IMAT combines imaging and diffraction techniques to capture previously elusive details about the structure of materials. One of the first experiments on IMAT was looking at an Amati violin, are exploring how the millimetre thick wood was used to construct the famous violins, and how small details of the instrument’s shape influence the sound production.
These studies underline the versatility of neutron imaging, which can give us insights into objects as different as historical musical instruments and modern aeroplane wings and engines. With the insights gathered via cutting edge science, careful conservation of these beautiful instruments is possible. Some may even be played, allowing us to muse on how well the music of the past still resonates with us today.
 Kardjilov, Nikolay, and Giulia Festa, eds. Neutron Methods for Archaeology and Cultural Heritage. Springer, 2016.