Notre-Dame de Paris
Clock

The first clocks used at Notre-Dame were clepsydras. These were used to tell the hours, which were marked by striking bells. In the 14th century Notre-Dame had two clepsydras running simultaneously, one in the cloister and one in the church itself. A lay chamberlain was responsible to keep the clocks filled with water and to notify a churchwarden when it was time to strike the bells for the hour.

In 1766, Guillot de Montjoye and Jean-Bernard de Vienne, canons and stewards of the church fabric, donated a mechanical clock to the cathedral. The movement was installed in a glass cabinet in the gallery beneath the north rose window and rang three bells placed outside above the north portal. Between 1812 and 1813, the clock and bells were moved to the north tower. A 1.34-metre (4.4 ft) clock face was installed inside the church below the organ platform.

During Viollet-le-Duc's restoration in the 19th century, a new clock was made. The 1867 Collin-Wagner movement, measuring two metres (6.6 ft) across, was located in the forest underneath the central flèche within a glass-enclosed room. This controlled four dormer clock faces visible on the transept roofs, two on each side. This clock was destroyed by the 2019 fire. Shortly after the fire, French clockmaker Jean-Baptiste Vior discovered an almost identical 1867 Collin-Wagner movement in storage at Sainte-Trinité Church in northern Paris. Olivier Chandez, who had been responsible for the upkeep of Notre-Dame's clock, described the find as "almost a miracle." While the clock cannot simply be installed in Notre-Dame itself, it is hoped that the clock can be used to create a new clock for Notre-Dame to the same specifications as the one which was destroyed.
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