The Enlightenment fosters the scientific precision. In addition to the technical achievement already in combination with multiple complications, very competent astronomers such as Lalande and Cassini adjust the astronomical tables and mathematicians like Camus position their gears and wheels.
At the end of the reign of Louis XIV, Jean Pigeon realizes a moving sphere clock on the principle of Copernicus and publishes his invention in 1714. The astronomical clock by Passemant is presented in 1749 at the Royal Academy of Sciences and is used to set the official time of the kingdom. It is kept at Versailles.
The Prince of Conti had little skill in politics but became the greatest collector of his time. Resolutely dismissing the academies and corporations, he commissioned around 1770 the most complex astronomical clock of his time. The clockmaking is made by Mabille and the spheres by Baffert, certainly before 1773 which is the date of bankruptcy of the latter.
The clock displays all the possible elements for measuring time and a beautiful dial for the position of the moon. Extended to the outer planets, the planetary includes six rotating spheres with the highest scientific accuracy. It also marks ecliptic, solstices, equinoxes and zodiac.
Janvier, who had this piece in hand after the Révolution, noted that it is better than Passemant's clock by the accuracy of its annual rotation because it incorporates the calculations published by Camus in 1749.
The planetary clock of the Prince de Conti is estimated £ 600K for sale by Christie's in London on July 9, lot 9.