Important Collectors Wristwatches, Po...

Geneva, Nov 14, 2009

LOT 217

Skeleton Clock with Pin-Wheel Escapement Le Roy, Hr. de Madame a Paris, No. 340B. Made circa 1810. Very fine and rare, gilt brass and black marble, center-seconds, 8-day going, hour and half-hour striking precision skeleton clock with pin-wheel escapement and half-seconds beating 9-rod gridiron pendulum.

CHF 20,000 - 30,000

USD 20,000 - 30,000 / EUR 13,000 - 20,000

Sold: CHF 40,800

C. A-shaped brass frame with four turned pillars, toupie feet, octagonal black marble base, gilt brass engine-turned bezel. D. Convex white enamel with radial Roman numerals, outer minute track with Arabic 15-minute numerals, inner seconds track with half-second divisions. Black Breguet hands. M. Going barrels for both trains, pin-wheel escapement, crutch with beat adjustment screw, brass and steel 9-rod gridiron pendulum with spring suspension, elliptical brass-bob with rating nut, striking the hours and half-hours on a bell with outside countwheel. Dial signed, movement signed ?L? and numbered. Dim. 38 x 27.5 x 12 cm.


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Grading System
Grade: AAA

Excellent
Case: 3

Good
Movement: 3*

Good

Overhaul recommended, at buyer's expense
Dial: 2-01

Very good

HANDS Original

Notes

The Pin-Wheel Escapement This escapement was particularly popular in France and was invented by Louis Amant in 1741. The teeth of the escape wheel are replaced by pins standing vertically from the plane of the wheel. A swinging pair of levers attached to the pendulum allows the pins to ?escape? one by one, this also impulses the pendulum. The pin-wheel escapement is quite accurate and only needs a small pendulum arc making it suitable for precision clocks.
Gridiron Pendulum The rod is composed of separate bars of brass and steel rods having different coefficients of expansion, so that the pendulum has the same length at any temperature. John Harrison used 9 bars of brass and steel when he first introduced the design in 1729. Some gridiron pendulums use fewer rods and different metals.
Madame The dial inscription ?hr. de Madame? refers to Napoleon?s mother, Madame Mere. As Emperor, Napoleon bestowed on his mother the title of ?Son Altesse Impériale, Madame Mère de l'Empereur? (Her Imperial Highness, Mother of the Emperor). He also gave her an annual pension of 300,000 francs, and a house with full staff, including a priest, ladies in waiting and servants.