Breguet Pendule à Trois Roues
This in-depth look examines Abraham-Louis Breguet's "three-wheel pendulum clock" (Pendule à Trois Roues), a radical horological concept developed in the late 18th century. Breguet deposited a sealed description of the clock's movement with the Académie Royale des Sciences in 1788, a claim to priority that remained unexamined for nearly a century. The article delves into the historical context of reducing wheel counts in clock movements, Breguet's specific technical solution, and the creation of the first example, No. 173.
- Sealed description deposited with Académie Royale des Sciences on February 3, 1788
- Envelope opened on December 5, 1881
- Movement built around three wheels
- First construction, No. 173, began February 22, 1792
The Pendule à Trois Roues was A-L Breguet's answer to the question of how much a clock's mechanism could be reduced without sacrificing precision.
Breguet used the 'pli cacheté' (sealed envelope) method, common in French scientific culture for securing dated records of priority, only once for a clock.
The concept of reducing wheel count in clock movements was not new, with earlier examples from Pierre LeRoy and Jean-André Lepaute, and a different approach by Benjamin Franklin.
Breguet's ambition for the Pendule à Trois Roues was to create a precision regulator capable of running for a full week, displaying the equation of time and both Gregorian and Republican calendars, regulated by a compensated pendulum.
The first clock, No. 173, involved Breguet himself for the movement and base, Le Maire for the escapement, and Desborde for the frame.
Breguet purchased No. 173 back from the registers in March 1793 and later gifted it to the mathematician Pierre-Simon Laplace.
The clock featured an equation of time cam and a pin-wheel escapement designed to minimize energy transfer to the pendulum.