LEIA

Foreword

On 9 September 2020, in collaboration with the Römisch-Germanisches Museum and the Institut Technologique Européen des Métiers de la Musique, our team studied a lyre bridge discovered in the 19th century in a Merovingian grave. Since its discovery, the object has had a troubled history: it disappeared for several decades into private collections before being bought as part of a lot by the Römisch-Germanisches Museum, which has kept it in its stores ever since. Although the object is mentioned in some publications, no in-depth study had ever been devoted to it. What does it weigh? What are its exact and complete measurements? What is it made of? What were its possible functions: only symbolic, or functional and musical? All these questions remained unanswered. Given how little is known about musical practice in the Early Middle Ages, and considering the means now at our disposal, it seemed obvious to us not to leave such an exceptional object in the shadows any longer, and we set out to give it all the attention and care it deserves. Over two years, this mission brought together nearly 40 project contributors of 4 different nationalities. Everyone's skill and professionalism allowed the project to run smoothly, combining Science, Craft and Art. We hope this multidisciplinary approach will advance research and offer both the general public and professionals a better understanding of the musical customs of the Merovingian period.

The one and only known photograph of the object before the mission. Dated 1920, this document was kept in the archives of the Römisch-Germanisches Museum.

The mission

Phase 1: metrological analysis, creation of a digital database

Carry out a series of surveys with today's means (photography, digitisation, photogrammetry, measurements) in order to enrich the data on this artefact, of which there was only one photograph from 1920 and almost no information about its nature, the context of its discovery, or its possible function or functions.

Phase 2: research, reconstruction

The aim here will be to develop a non-destructive methodology to identify the composition of the object and the nature of its alloy in its exact proportions, without taking any sample. Identifying the alloy and the structural mass properties of the object will make it possible to build a digital model with which several experiments and simulations will be carried out. These analyses will also make it possible to produce a highly accurate facsimile of the object. This facsimile will be based on the data produced in the previous stages and will be made through an experimental archaeology protocol reproducing as faithfully as possible the production methods of the Merovingian period, for a result as close as possible to historical reality. Once the facsimile has been checked against the original, within an acceptable margin of variation, we will be able to carry out experiments in a musical setting with two instruments reconstructed by the same process.

Phase 3: publication, public engagement, virtual exhibition, lecture, concert

As with every PRIAE project, the end goal is transmission and accessibility. We will therefore conclude this research with several publications for professionals, researchers and students in peer-reviewed scientific journals and bulletins, and for the general public in popular science magazines, on radio and television, etc.

In addition to a page devoted to the mission on the PRIAE website, where all the data produced can be consulted (photos, videos, 3D documents, etc.), we will produce a free virtual exhibition that will let the public discover the subject in an immersive and interactive way. Our work will also contribute to the permanent display of our partner, the Römisch-Germanisches Museum.

During 2021, 2022 and 2023, three lectures will be given at the Musée royal de Mariemont (Belgium), at the archaeo-lutherie conference in Saint-Guilhem-le-Désert, and in the auditorium of the Musée d'Archéologie nationale in Saint-Germain-en-Laye.

Finally, to make room for music and offer the public a discovery through music, an original work built around the reconstruction of the bridge and of the instrument will be commissioned from the ensemble The Dragon and the Dove, which for the occasion will bring together an international team of instrumentalists from the Royal Academy of Music in London and the Royal Conservatoire in Edinburgh, as well as singers from Université Montpellier III.

Methodology

3D digitisation

This method creates a digital copy of an object using a scanner. It first enriches digital databases, making the work of researchers and students around the world easier. The 3D document preserves the geometry of the object digitally, and even its colour when combined with photogrammetry, which proves invaluable when artefacts deteriorate (naturally, through vandalism, etc.) or are stolen or lost. The 3D document also opens up many possibilities for public engagement: online virtual museums, technological mediation modules such as holograms, or the production of facsimiles. Here, the digitisation will be carried out with the Artec™ Spider scanner and will capture the geometry of the object, which is essential to our study.

Laser vibrometry

Laser vibrometry measures, without contact, the vibrations on the surface of an object. Analysis then determines the resonance modes of the structure, that is, the very particular ways in which it vibrates according to frequency. Combined with 3D digitisation and simulations, this approach identifies the mechanical properties of the object (stiffness, damping); valuable elements which, combined with the other surveys, make it possible to draw up a precise "identity card" of its composition.

Conductimetry

Studying the electrical properties of the object provided further information, since the electrical resistance of an object is also an indicator of its nature. This makes it possible to assess the composition of the object non-destructively, so as to support the reconstruction work by staying as close as possible to the materials used and their proportions.

Result of the combined analysis

The non-destructive method we developed proved a clear success thanks to this combined approach, involving several metrological processes whose results converged on the identification of the composition of the alloy without any sample being taken.

The weight of the artefact, combined with its volume revealed by 3D digitisation, and with its conductivity and its vibrational and mechanical properties identified by vibrometry, converge on a model of a bronze composition with a ratio of 91% copper to 9% tin (a ratio consistent with the proportions commonly observed in bronze-making in Antiquity and in the Gallo-Roman period). Given its success, this new methodology for identifying the nature of a metal object non-destructively will soon be the subject of a publication.

Reconstruction of the bridge

For the rest of our experiments, we needed to reproduce the bridge as faithfully as possible in both shape and composition, so we produced a polymer matrix of the bridge from the 3D document made earlier. For the casting itself, we chose to reproduce the technique used in the Merovingian period, through experimental archaeology and the lost-wax process, scrupulously respecting the proportions of copper and tin identified by the analyses. Once it was made, we subjected the facsimile to the same examinations as the original artefact to check its conformity before moving on to the next experiments. The result showed that the facsimile is similar to the original in weight, volume and vibrational behaviour, with a variation of only 6%. The facsimile is therefore almost identical to the original and will be a valuable element for future experiments.

Reconstruction of the instrument

To test the facsimile in a musical setting, we faced a difficulty. It would have been desirable to reconstruct the instrument that accompanied the bridge in the Merovingian grave, but according to the archaeological report there was none. Either no instrument was buried with the deceased, only the bridge (whose true nature the archaeologist of the time did not know, describing it as a "curious prismatic object"), or the instrument was so degraded by poor humidity conditions that its fragments went completely unnoticed (the methods of 1870 were not those of today, which also explains how the object disappeared into private collections). In any case, we have no data on the nature of the instrument that may have accompanied this bridge in the grave, if there ever was one. So, to test the bridge with an instrument relevant to the experiment, we selected possible candidates by identifying the instruments discovered by archaeology that date from the same period, come from the same people and have the same number of strings (in short, an instrument on which the bridge would most plausibly have been fitted at the time). We chose two instruments, so as to have two variables and be more objective: the Cologne lyre, discovered in the chapel of St. Severin in Cologne (7th century), and the lyre discovered in the Württemberg necropolis of Oberflacht (7th century). Besides their closeness in time and place to our subject of study, both lyres were discovered without bridges, unlike the Trossingen lyre (6th century), which would otherwise also have been an excellent candidate. The instruments were reconstructed from data provided by the museums of Cologne and Stuttgart, following an experimental archaeology protocol taking into account the tools, techniques and materials identified on the remains of the instruments. A tool kit was specially forged after tools found on several Merovingian sites and necropolises (Concevreux, Avranches, Saint-Dizier, Württemberg).

Conclusion of the experiment

The digital analyses and the playing experiments show that the bronze bridge of Concevreux is fully functional as a musical part. In the light of our conclusions, nothing suggests that this object could not have been used on an instrument.

Virtual exhibition, lecture

To share our work with a wide public through contemporary means, we decided to create a free virtual exhibition (see below) in which visitors can browse the photographs taken by our photographer Laureen Keravec. Visitors can also handle high-definition 3D documents of the Concevreux bridge and the Cologne lyre. Each stage of the mission is explained by the project contributors in short videos. It is also possible to watch the whole presentation lecture on the LEIA project given by Julian Cuvilliez at the Musée royal de Mariemont, and to listen to the musical composition performed on the reconstructions by Ar Bard Production and the ensemble The Dragon and the Dove. Alongside this 360° virtual environment made by our partner E-Mage-In 3D, we offer the public a download link for the exhibition in Full HD, which allows complete freedom of movement and access to additional interactive mediation modules never seen before. Finally, we recorded in the studio the different notes of the reconstruction of the Cologne lyre and the Concevreux bridge and sampled them to create an interactive virtual instrument that the public can now play with a computer keyboard.