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Experts are studying the melted lead from the fire that ravaged the Notre Dame cathedral.

Ashes of Notre-Dame to Reveal Secrets of Medieval Architecture

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The remains of last year s burning of Paris s Notre-Dame cathedral will be studied by scientists.

On April 15 of last year the world froze as an electrical fire destroyed the cathedral’s roof and spire and caused part of its vaulted ceiling to collapse. The incident was declared a national tragedy and now scientists from the French national research organization CNRS have embarked on a multimillion-euro study of the innards of the 850 year-old holy building to learn more about how the medieval masons constructed it.

Hoping their work will help with the impending restoration the scientists will examine the foundations, timber, and metalwork. Quoted in an article on Nature.com, Dr. Yves Gallet, a historian of Gothic architecture at the University of Bordeaux-Montaigne, said the new research project might write a “new page in the history of Notre-Dame”, admitting there are “currently many grey areas”.

Studying The Work Of Past Masters

Dr. Gallet is in charge of a 30 strong research team investigating the construction of the 12 th century cathedral, which was modified in the Middle Ages and again restored in the 19th century by architect Eugène Viollet-le-Duc. Whether Viollet-Le-Duc reused some of the older materials is the question being asked by Martine Regert, a biomolecular archaeologist at the CNRS s CEPAM center for the study of historical cultures and environments in Nice, who is one of the new Notre-Dame project s leaders.

Notre-Dame de Paris before the fire, restored in the 19 century by architect Eugène Viollet-Le-Ducin

Notre-Dame de Paris before the fire, restored in the 19 century by architect Eugène Viollet-Le-Ducin. (Mschlindwein / CC BY-SA 3.0 )

To answer this question, and others, the researchers will delve into fallen stonework, burnt timbers, and fire scorched metallic artifacts and radar imaging will examine the foundations, said Philippe Dillmann, a specialist on historical metal artifacts at the CNRS Laboratory for Archaeomaterials and Alteration Forecasting in Gif-sur-Yvette, who is coordinating the project with Regert, in the Nature article.

A 100 Strong Team of Scientists

The CNRS project will involve a massive effort of 100 researchers in 25 laboratories and will last for six years studying: “masonry, wood, metalwork, glass, acoustics, digital data collection, and anthropology”. Studying the mortar between the stones the researchers aim to reveal how different compositions were used for vaulting, walls, and flying buttresses. Furthermore, the lime used to make the mortar came from fossil rich sedimentary limestone that might could reveal where it originated, says Gallet.

And the team of historical forensics detectives led by Dr. Gallet will study the stones at Notre-Dame to identify the quarries in which they originated attempting to reconstruct the supply networks and the economy of the site. Another aspect of the project aims to study the structures weaknesses, to the masonry, which were damaged by the high temperatures of the 2018 fire, and a ground penetrating radar study will help scaffolding builders assess where to erect their poles to dismantle the unstable remnants of the damaged 19 th century spire.

Notre Dame cathedral, reinforcement work in progress after the fire, to prevent the cathedral from collapsing

Notre Dame cathedral, reinforcement work in progress after the fire, to prevent the cathedral from collapsing. ( UlyssePixel / Adobe Stock)

Gathering Metallic Clues

The burnt cathedrals metalwork will be studied by a team of specialists led by archaeologist Maxime L Héritier of the University of Paris, who told Nature that a study of changes in the use of iron in cathedral building over such a long period, from the Middle Ages to the 19 th century, will be exceptionally revealing.

Studying melted lead from the roof will allow the researchers to develop a ‘chemical reference data set’ of the ratios of lead isotopes and the presence of trace elements in the material. This, says Dr. L Héritier, will provide an understanding of “the evolution of lead quality and supply” and maybe even the mines from which the metal came.

Knowledge Entombed In Wood

Another team of 50 scientists will centralize their work on Notre-Dame s famous woodwork and especially on the forest of timbers’ above the vaults in the roof which lies charred and destroyed in the nave, and while it looks horrific to outsiders, these broken wooden rafters reveal a treasure chest of data and hitherto concealed microbic information pertaining to the building of what is among the greatest structures built anywhere on the planet.

Alexa Dufraisse, an archaeologist at the National Museum of Natural History in Paris, will lead the multidisciplinary wood team and she describes the burnt structure as constituting “a gigantic laboratory for archaeology” as while it is known the ‘forest’ is made of oak, little is currently known about the ancient techniques and tools used by the medieval carpenters.

A Long List Of Skill Sets

All this work will focus on three main piles of debris located in the nave and on top of the vaults, and the samples will be collected by robots and drones, with some of the recovered materials hopefully reused in the forthcoming restoration project .

Arch at Notre Dame cathedral, before the fire, shows the elaborate construction and skills of the medieval masons

Arch at Notre Dame cathedral, before the fire, shows the elaborate construction and skills of the medieval masons. (Pxfuel / Public Domain )

All of the collection and data analysis will be documented by Livio de Luca, a specialist in digital mapping of architecture, at the CNRS s Mixed Research Unit in Marseille, who says she will create a ‘digital ecosystem’ based on the work of all the scientists which include: historians, archaeologists, engineers, curators, dendrochronologists, climatologists, biogeochemists, carpenters, foresters, and engineers, to name a small section…

Top image: Experts are studying the melted lead from the fire that ravaged the Notre Dame cathedral. ( lorabarra / Adobe Stock)

By Ashley Cowie

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