Barometers Realm

Presented here is a rare Miniature Brass-cased Aneroid Barometer, dating to approximately circa 1870, produced by the renowned French firm Dubois & Casse—one of the key workshops at the forefront of early aneroid mechanism development in France. The defining feature of this instrument lies in its unusual concept: it represents a miniaturized version of a standard wall-mounted aneroid barometer, executed with remarkable precision at a reduced scale. With a case diameter of only about 70 mm, it stands apart from typical examples by the firm while nonetheless remaining a fully functional and highly accurate scientific instrument.

The case exhibits a characteristic barrel-shaped form, typical of French aneroids of the period, and is crafted from tombac alloy—a copper-rich brass that imparts a soft, warm golden tone to the surface. The exterior is finished with a delicate satin brushing, emphasizing both its sculptural coherence and artisanal origin. The instrument is fitted with a fine suspension ring at the top of the case, faithfully echoing the construction of its full-sized wall-mounted counterparts. On the rear cover appears the firm’s well-known trademark—an anchor flanked by the letters D and C, identifying Dubois & Casse.

The front is framed by a thin, finely profiled bezel retaining a flat mineral glass with a faceted edge, creating a subtle play of light along its perimeter. At the center of the glass is a brass trend indicator hand, fitted with a knurled knob, allowing manual adjustment to track changes in atmospheric pressure.

The dial features an open-work construction, characteristic of high-grade aneroids of this period, and is made of silvered brass. It is engraved with a finely executed concentric barometric scale, calibrated in centimeters of mercury from 58 to 79 cm. The scale is accompanied by traditional French weather indications, rendered in a characteristic combination of serif and sans-serif lettering, lending the dial a distinctive graphic clarity. The primary indicating hand is slender and elegant, made of steel and finished by heat bluing, giving it a deep dark tone and enhanced resistance to corrosion.

At the lower edge of the dial appears the name of the retailer—Maison Berthiot, Cordier Sr., opticien à Lyon. This refers to a mid-19th-century optical workshop and commercial house associated with the wider network of French optician-craftsmen. The name Berthiot represents a well-established family tradition in optics, with branches in Paris and the provinces, later developing into industrial optical production. The Lyon establishment functioned as a regional branch or representative. The founder of the family line was Louis-Jean-Baptiste Berthiot (1807–1857), while Cordier is recorded as his successor.

At the heart of the instrument lies its mechanical core—the aneroid movement, executed with notable precision. The construction is based on a 40 mm aneroid capsule made of nickel silver, tensioned by a steel C-shaped spring mounted on a substantial lever, whose arms rest on characteristic square-headed screws, a typical feature of Dubois & Casse mechanisms. Motion is transmitted to the indicating arbor via a fusee chain, ensuring smoothness and accuracy of operation.

In summary, this barometer represents a rare and refined synthesis of miniaturization, mechanical ingenuity, and aesthetic sophistication, characteristic of the finest examples of 19th-century French instrument making. It is not only a precise measuring device but also a compelling testament to an era in which scientific instruments were conceived as objects of both intellectual and artistic value.