It’s not often that historic preservation work makes it into a journal like Science, but the work at Notre Dame de Paris is special. “Scientists are leading Notre Dame’s restoration—and probing mysteries laid bare by its devastating fire” by Christa Lesté-Lasserre is a thorough discussion of the conservation work going on following the April 2019 fire.
While structural engineers have been involved since the immediate aftermath of the fire, and will be involved until the roof and vault structure is completely restored, the focus of the article is simultaneously smaller- and larger-scale. People are working to examine disparate construction materials – roof timbers, vault limestone, iron bolts, lead roofing – to understand more about their original construction, past restoration work, and the effects of the fire. I’m not going to repeat the article: read it, it’s worth the time.
I have used the picture above before, but I want to repeat its importance. That photo was taken in 1852 or 1853 by Édouard Baldus, which is in itself worthy of note. That date puts it towards the beginning of the restoration of the cathedral by Eugène Viollet-le-Duc, and some of that working progress is visible around the base. Most notable is that the new central crossing spire, built as the part of the restoration to replace the spire town down in the 1780s, is not yet there. The collapse of the nineteenth-century spire was one of the most dramatic moments of the recent fire, and created the largest piece of damage to the vaulting.