The Private Collection of Theodor Beyer

Hotel Baur Au Lac, Zurich, Nov 16, 2003

LOT 72

Du Bois & Comp. (Locle), No. 38010, circa 1820, movement by Jacques-Frédéric Houriet, No. 58. Highly important and extremely rare 18K rose gold key-wound pocket chronometer with one-minute tourbillon regulator, spring detent escapement, free-sprung spherical isochronical balance spring, Réaumur bimetallic thermometer, stop feature, and regulator dial.

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C. Four-body, massive, "bassine et filets", engine-turned back, gold hinged cuvette with winding aperture, inscribed with details of the movement. D. White enamel, small radial Roman hour chapter at 10 o'clock, central minutes with outer divisions and fifteen-minute Arabic markers, Réaumur thermometer sector at 6, subsidiary seconds at 2 o'clock. M. 50 mm (22'''), frosted gilt U-shaped plate, fusee and chain with Harrison's maintaining power, Earnshaw type spring detent escapement with gold escape wheel, two-arm cut bimetallic compensation balance with Earnshaw type gilt wedge temperature compensation weights, polished steel mean temperature screws, blued steel free-sprung spherical balance spring, the whole on two-arm steel carriage rotating around gold fourth wheel.Punched with the Houriet's mark "FH" on the pillar plate under the dial, the dial and cuvette signed by Du Bois.Diam. 58 mm.

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Grading System
Case: 2

Very good

Movement: 2

Very good

Dial: 2-01

Very good

HANDS Original


It is extremely rare to be able to examine such an early tourbillon watch made by one of the best makers of the time. After Breguet, Houriet was probably the first to try his skills in tourbillon making. The finish and the attention paid to detail are remarkable. From a technical point of view, the watch is extraordinary. The circumference of the balance is precisely graduated for accurate temperature adjustment, a feature found sometimes in special marine chronometers but hardly ever in pocket watch movements. It is finished with undercut on the laminae segments for the temperature weights, to make sure that they are not moved too far. The steel blocks on the balance arms for the mean time adjustment screw are not only superbly polished but are made long and are slotted for friction fit of the screws to make sure that they will stay securely after the adjustment. For the balance spring Houriet chose a spherical shape, which reduces the effects of decentralization of the spring. Houriet asserted that this form enables the balance to perform the greatest possible arc of oscillation for a given impulse. It is interesting to note that his technology for making these springs has survived: he employed a mold consisted of two parts fitting one into the other, on which were adjusted five brass discs. He turned this system into a sphere flattened at the poles and traced a tread on it with a fusee engine.Reinhard Meis, in his "Le Tourbillon", Editions de l'Amateur, Paris, 1990, devotes two pages to this watch (116-17).