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Hotel Nogalhilton Geneve, Nov 11, 2001

LOT 8

Precision Timekeeper with 2 Complications and ThermometerLe Paute a Paris, cabinet by Jean-Ferdinand-Joseph Schwerdfeger, circa 1775.Very fine and extremely rare month-going weight-driven Valet Astronomique, with long case regulator, Huygens endless rope-winding, Berthoud offset compound pendulum, center-seconds, equation of time, annual calendar and thermometer.

CHF 200,000 - 250,000

USD 125,000 - 156,000

Sold: CHF 223,500

C. Mahogany, glazed on the front, rectangular cresting above molded cornice supported by wooden corbels, paneled veneered plinth with molded base. D. By Barbezat, white enamel, Roman numerals, outer minute dot divisions with five-minute Arabic markers, the center with rotating equation dial with red Arabic numerals. Annual calendar in aperture above 12 o'clock. "Louis XV" gilt brass hands. M. Circular brass movement, 17,5 cm, contained in a brass cylinder, cylindrical pillars with conical base,eight-driven, pin-wheel escapement with pins on one side of the escape wheel, heavy asymmetrical brass-steel Berthoud compound compensation pendulum with thermometer scale, spring suspension, Huygens endless rope winding, 146-tooth annular wheel driven by six-leaf pinion of 30-tooth star wheel jumping twice a day, equation cam set on the annular wheel, equation arm connected to a rack meshing with a wheel set underneath the equation dial which is spring loaded via a small cord and long steel sprng.Signed on the dial.Dim. 185 cm, base width 44 cm.


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Grading System
Grade:
Case: 3

Good
Movement: 3*

Good

Overhaul recommended, at buyer's expense
Dial: 3 - 13 - 01

Notes

The fact that a Berthoud offset compound pendulum was employed in a Valet Astronomique made by Lepaute shows the great influence of Berthoud's ideas on watchmakers of the time.The Berthoud offset compound pendulumInvented by Ferdinand Berthoud, the offset pendulum is described in his Essai sur l'Horlogerie, 1763, vol. 2,pl. XXXIV, pp. 302 and 303. It is constructed from three bars only, two of steel, one of brass. In order to perfect the compensation, F. Berthoud devised an auxiliary adjustable compensation lever, mounted between the bar of brass and one of the steel bars. The pendulum is also fitted with a thermometer. The bob is offset relative to the center line of the pendulum, apparently to avoid any distortion of the bars. At rest, the gridiron is therefore at an angle from the vertical. This type of pendlum was soon abandoned in favor of the 9 rod gridiron pendulum. To date, only five regulators, including this lot, fitted with this form of pendulum are known, one of which is preserved in the Musée National des Techniques (C.N.A.M.), Paris.For equation of time, see lot 30.