Notre Dame's New Bells Will Peal on Palm Sunday in Paris

A ceremony to inaugurate nine new church bells on Feb. 2 at Notre Dame Cathedral in Paris Photograph by Kenzo Tribouillard/AFP/Getty Images

Until recently, precisely every 15 minutes a discordant clang bong-bonged from the cathedral of Notre Dame.

This racket had been heard in the heart of Paris since the 1850s, when the cathedral was fitted with what most Parisians would agree were “France’s most out-of-tune church bells.” Good thing Quasimodo went deaf.

“Notre Dame was very well-known for the sound of its bells, that is, until the French Revolution,” says Paul Bergamo, president of Cornille-Havard, the country’s most renowned bell foundry. Shortly after Marie Antoinette was hauled off to the guillotine, Bergamo says, the young republic ordered the removal of some 10,000 bells from the belfries of France to be melted down and made into cannons and coins. Not even Notre Dame, France’s most celebrated cathedral, was spared from this act of state-sanctioned vandalism.

Its biggest bell, a 13-ton bourdon bell named Emmanuel, remains to this day, but the other nine were destroyed, later replaced by a set of four bells that Parisians have cursed for more than a century.

In the coming days, Emmanuel will get new company, a set of nine new bells, eight of which were cast by Cornille-Havard. They will ring from the 850-year-old cathedral in time for Palm Sunday Mass. “This is just the second set of bells since the French Revolution. They will ring as the bells did in the 1700s,” says Bergamo. Parisians, you can remove your fingers from your ears.

Bergamo’s foundry was chosen because of its breakthrough work in bellfounding. Cornille-Havard is at the forefront of a new approach to bell design, using computer modeling to plot the bells’ optimal “geometry”—or the precise shape, thickness, and weight of the bell to deliver a consistent and consistently sharp tone.

For centuries, bellfounding was an imprecise process, done by eye, hand, and ear, with varying results. The problem was that once a several-ton bell is cast you could do very little to smooth the frequent tuning irregularities that arose from the final shape, Bergamo says. It is possible to grind out further the hollow of the bell, a process called “machining,” but not too much or it will weaken and crack. “With machining you can get a lower note, you can correct small defects, but you cannot correct everything. And you cannot get a higher note,” he says. “By working with computer modeling we can get closer and closer to the final note we wanted before we even cast the bell.”

The result is that today’s computer-designed church bells pack a crisper, more consistent tone than their predecessors’, that can be heard farther away. The peals may be louder but they are more pleasing, too. Bergamo is confident Notre Dame’s new bells will deliver pitch-perfect tone every day for up to 300 years, an unheard-of boast from a bell maker. “The last set of bells went out of tune right after they were hung,” he says, a common problem in those days.

The Notre Dame project was a massive task. Bergamo and his team designed and manufactured eight new bells over a break-neck 11-month period in 2012, part of a €2 million ($2.5 million) project financed primarily by L’Oréal heiress Liliane Bettencourt on behalf of the cathedral; Bergamo managed the casting of a ninth bell at a second foundry. The nine bells weigh a combined 23 tons.

Bergamo says for the major bell foundries of Europe, these are busy times, driven by the sound of a new generation of superior-sounding bells pealing at midday. He says that often after his team hangs new bells, a neighboring mayor or church official will call the foundry inquiring how they, too, can upgrade. “For us, there is no crisis,” he says.