Jonathan Snellenburg
Director
Lot 10
A VERY FINE MAHOGANY MONTH-GOING LONGCASE REGULATOR OF SMALL SIZE, WITH REMONTOIRE, EQUATION OF TIME AND REVOLUTIONARY CALENDAR
Jean Simon Bourdier, Paris, Circa 1800
20 October 2022, 10:00 EDT
New YorkSold for US$44,475 inc. premium
Looking for a similar item?
Our Watches specialists can help you find a similar item at an auction or via a private sale.
Find your local specialistAsk about this lot
A VERY FINE MAHOGANY MONTH-GOING LONGCASE REGULATOR OF SMALL SIZE, WITH REMONTOIRE, EQUATION OF TIME AND REVOLUTIONARY CALENDAR
Jean Simon Bourdier, Paris, Circa 1800
Movement: In two parts: the pinwheel escapement, motion work and equation cam planted on a square plate joined by four screwed pillars to a back plate secured to the case and supporting the massive nine rod gridiron pendulum by means of a knife edge resting on a pivoted block; above this, a separate remontoire mechanism fixed by screws to the upper two pillars consisting of a pair of rectangular plates carrying twin going spring barrels driving a pulley suspending two small weights by an endless cord released at intervals by a link to the larger descending weight
Dial: White enamel with Arabic minute ring enclosing roman chapters and inner seconds ring, pierced gilt mean time hands, blued Equation hand and blued seep seconds hand; below, a portion of the silvered year calendar ring labeled with both Gregorian and Republican months; the current date indicated by a fixed blued arrow hand
Case: Caddy top with dentil molding above the glazed long door on a molded plinth base
Size: 76 in (193 cm) high
Movement: In two parts: the pinwheel escapement, motion work and equation cam planted on a square plate joined by four screwed pillars to a back plate secured to the case and supporting the massive nine rod gridiron pendulum by means of a knife edge resting on a pivoted block; above this, a separate remontoire mechanism fixed by screws to the upper two pillars consisting of a pair of rectangular plates carrying twin going spring barrels driving a pulley suspending two small weights by an endless cord released at intervals by a link to the larger descending weight
Dial: White enamel with Arabic minute ring enclosing roman chapters and inner seconds ring, pierced gilt mean time hands, blued Equation hand and blued seep seconds hand; below, a portion of the silvered year calendar ring labeled with both Gregorian and Republican months; the current date indicated by a fixed blued arrow hand
Case: Caddy top with dentil molding above the glazed long door on a molded plinth base
Size: 76 in (193 cm) high
Footnotes
An important example of late 18th century French precision clock making. The regulator incorporates a superb gridiron pendulum, visible through the trunk door, to compensate for the effect of changing temperature.
The clock employs a remontoire, a device rewound by the mainspring at short intervals to deliver constant force to the train, eliminating the possibility of diminished power from the unwinding of the coiled spring.
The clock has two minute hands to correctly displays true Solar Time as seen on a sundial in addition to the Mean Time measured by a mechanical clock by using an "Equation of Time" cam linked to the additional hand. Not incidentally, Julian LeRoy, a leading French clockmaker of the mid-18th century declared that the ability to make an equation clock was the true test of a master clockmaker.
Solar time varies constantly throughout the year requiring a calendar mechanism in the clock. The silvered calendar wheel is visible at the top of the trunk door. The equation cam can be seen behind it.
Finally, the calendar displays both the conventional months of the year and the months of the French Republican calendar. Also commonly called the French Revolutionary calendar, the calendar was created and implemented during the French Revolution, and used by the French government for about 12 years from late 1793 to 1805, and for 18 days by the Paris Commune in 1871.
