An object from Louis Pasteur's study, on the ground floor of his apartment at the Institut Pasteur, has recently been handed to specialist restorers. This exquisitely elegant Louis XV cartel clock made by Joannes Biesta is both a masterpiece of French 18th-century craftsmanship and a valuable insight into the family history of Louis and Marie Pasteur.

The cartel clock – the ultimate expression of ornate clockmaking
The cartel clock, which first originated in France in the early 18th century, is a prestigious wall clock. The name refers to both the clock itself and the sculpted case in which it is set. Cartel clocks adorned the most sophisticated interiors belonging to the nobility and the upper classes. They were in vogue throughout the 18th century, and would be hung in reception rooms or bedrooms. They were designed to operate silently – master clockmakers would ensure that the mechanism did not make a ticking sound that could disrupt the tranquility of the elegant apartments where they were housed.

The cartel clock from Louis Pasteur's study is a fine example of the Louis XV style. Its violin-shaped case is made of green horn, a material that was highly appreciated at the time for its shimmering effect. It is decorated with carved elements in gilded bronze: scrolls sculpted in the round stand above the circular dial, whose white enamel numbers under glass reflect the virtuosity of the period's craftsmen. Beneath the dial, a peacock and arabesques complete the piece, which stands on four feet. Every 18th-century cartel clock was a collective undertaking that required close collaboration between cabinetmakers, bronziers, chiselers and master clockmakers. Cartel clocks particularly flourished in Paris but could also be found in Lyon, Dijon and the Jura region.

Joannes Biesta, a horologist recognized by the Royal Academy of Sciences
This cartel clock bears the signature of Joannes Biesta, who was born in The Hague in 1712 and died in Paris on August 21, 1791. The Dutch clockmaker and inventor became a French citizen on March 24, 1757, and came to be one of the key figures in Parisian clockmaking during the Enlightenment.

Biesta was not only a skilled craftsman; he was also an inventor who found himself embroiled in some of the major scientific and technical disputes of his day. In 1753-54, he was caught up in the conflict between the clockmaker Jean-André Lepaute and a certain Pierre-Augustin Caron (who later became known as Beaumarchais) over who had invented the double-virgule escapement. In 1757, he presented "an equation pendulum clock with astronomical indications with four concentric hands" to France's Royal Academy of Sciences, obtaining the Academy's seal of approval. In the 1773 edition of the Tablettes de la renommée, a register of famous artists, Biesta's name figures among the clockmakers who had "earned the votes and approval of the Academy of Sciences," the very institution to which Louis Pasteur was voted as an eminent member one century later (in 1862).

Biesta's ambitions went well beyond the workshops of Paris. In 1770, he submitted a marine clock of his own design for sea trials in the hope of winning a Rouillé de Meslay prize. The clock was damaged while being transported and did not function as planned, but some of Biesta's clocks were indeed taken on major scientific expeditions – in October 1772, when the frigate La Flore returned to Brest after a year-long expedition, the cargo included clocks made by Biesta alongside those of Leroy and Berthoud, two major names in French marine chronometry. Very few pieces by Biesta are still in existence, which makes the cartel clock in the Pasteur Museum all the more significant.

From Lyon to the Institut Pasteur: a family heirloom
The provenance of the clock is closely linked to the history of the Pasteur family. It can be traced back to the bedchamber of Aristide Laurent (1795-1869), Marie Pasteur's father, when he lived in the home of one of his other daughters, Madame Loir, in Lyon. He left it in his will, dated October 25, 1868, to his niece Louise Danicourt-Gribier, who in turn passed it on to her cousin Marie Pasteur.

The clock was displayed in the apartment belonging to Louis and Marie Pasteur from February 1889 onwards. It reminds us that the apartment, now the Pasteur Museum, not only houses Louis Pasteur's scientific instruments; it is also full of everyday objects that offer a glimpse into the life of the Pasteur family – a dimension that was particularly highlighted recently during the bicentenary of Marie Pasteur's birth, celebrated in January 2026.

Find out about the restoration of the cartel clock
The cartel clock is currently with specialist restorers, who are working to stabilize its condition and restore the luster of the original materials – the green horn used for the case, the gilded bronze of the Rococo ornaments and the white enamel of the dial. The restoration work is part of a broader effort to preserve and promote the collections from the apartment in preparation for the opening of the future Pasteur Museum.

To find out more about the restoration of the cartel, watch the first two episodes:
 

Episode 1 (click on the image)		Episode 2 (click on the image)
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