NOVA: "Saving Notre Dame" (Arte France, Sprockets Music, WGBH, PBS, 2020)

by Mark Gabrish Conlan • Copyright © 2021 by Mark Gabrish Conlan • All rights reserved

The TV show I watched last night was a surprisingly fascinating NOVA episode called “Saving Notre Dame,” which began with the disaster everyone remembers – the catastrophic fire that gutted the famous Notre Dame cathedral in Paris on April 15, 2019 – and both the imminent danger to the firefighters charged with putting out the blaze on the spot and the elaborate precautions that had to be taken to preserve what was left of the structure after the fire was out to make sure the walls didn’t collapse. The show also delved into the current attempts to reconstruct the cathedral, which has meant doing a lot of forensic architecture and archaeology to figure out how it was built, and what materials it was made of, in the first place. The famous roof was almost totally consumed in the blaze – the church’s iconic spire was the first item to go and only about 15 percent of the wooden beams holding up the roof survived in any form. The roof beams had been nicknamed “The Forest” because they literally took almost an entire forest to make – the estimate was that 55 oak trees were used – and they were shaped into curves to produce an elaborate birdcage -like structure that had to be duplicated exactly from similar oak trees in other French forests.

The basic building material for Notre Dame was limestone, a sedimentary rock that contains fossils of plankton and other small plants. The original 12th century builders used three different sorts of limestone: hard stone to build the structure-bearing walls and basic framework, soft stone for the sculptures lining the hallways and sides of the main chapel, and medium stone for the vaulted ceiling, since it needed to be strong but also flexible to withstand the elements and the gravitational forces at work on the building. Part of the problem was matching the properties of the original stone to what is available in France today – and the various fossils embedded in the stone were important clues as to what sort of stone went where. One of the issues facing the teams working on the restoration was that Paris has grown so much since the 12th century that both the original forest from which the oaks were harvested and the original quarries that produced the stones are no longer available. Indeed, one of the original quarries was turned into an ossuary in the 18th century, and the most macabre shot in the whole documentary was of a pile of skulls facing the camera as people involved in the restoration inspected it. (Given just when the place was dedicated to disposing of human remains, I can’t help but wonder how many of these skulls were of victims of the French Revolution and the ensuing Reign of Terror.)

My big takeaway from this show was an admiration I’d never had before for the technological know-how of the Middle Ages: the historical legend is that the science and technology developed in ancient Greece and Rome had basically been forgotten throughout the Middle Ages and was only rediscovered by the Renaissance, but ironically the near-destruction of Notre Dame showed off how meticulously it had been built in the first place and how much conscious thought had gone into the design and the selection of building materials to create a structure that would last for 900 years. There were also some interesting side issues, including the delicate process of cleaning the stained glass in the church’s famous display windows (one thing the medieval technologists hadn’t known about was the acute toxicity of lead; the fire released huge clouds of lead dust and the workers doing the post-fire cleanup had to wear haz-mat suits discarded after one use and go through a decontamination procedure before they could leave the site to go home, or even to have lunch). Fortunately the windows had been left so long without being cleaned that the thin film of dust between the windows and the lead made the lead easier to remove. The restorers are also considering a new technique for preserving stained glass that’s being tried in a similar restoration in England of mounting a modern framework with clear glass behind the stained-glass window to minimize its exposure to wind, water and other climate phenomena.

And there was a brief discussion of some plans for creating a futuristic new spire for the cathedral – including one that would have included solar panels – before French president Emmanuel Macron vetoed them and insisted that the post-restoration spire look the same as the original one. (Obviously he wants to avoid the issues that arose in the U.S. when the World Trade Center towers were replaced by something even less practical and more preposterously ugly.) Macron also had pledged that the cathedral would be completely rebuilt and open to the public by 2024 – a pledge the experts interviewed for this program conceded is unlikely to be fulfilled. It’s ironic that it took the near-destruction of Notre Dame to show the world how well it was built in the first place (though luckily there had been efforts to map the cathedral digitally in 2014 and 2016, and these preserved valuable information to guide the restorers in creating what they call the “digital twin” of Notre Dame which will map out the reconstruction of the physical structure), but I came away from this program with a lot more admiration for the technology of the Middle Ages than I’d had before.