Du Bois & Comp

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. Four-body, massive, "bassine et filets", engine-turned back, gold hinged cuvette with winding aperture, inscribed with details of the movement. Notes 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 sp