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aneroid capsule tensioned on a U-spring
brass, glass, nickel silver, steel
The “mysterious” design of aneroid barometers first appeared in France in the work of the clockmaker Antoine Redier by around 1890 and became widely adopted during the 1920s–30s by a number of European manufacturers, including Goerz, Zeiss-Ikon, Short & Mason, Jaeger-LeCoultre, Lufft, and others. Its defining feature consists of two transparent parallel glass plates — usually with faceted edges — one carrying the barometric scale while the indicating hand appears suspended between them, with the mechanism itself concealed from view. This combination of futuristic design and mechanical sophistication made instruments of this type unique and highly prized among collectors.
History and Evolution of the Design
The “Mystérieuse” design (from the French mystérieuse, “mysterious”) is associated with the effect of an “invisible” mechanism. In such barometers, two circular glass plates with faceted edges are mounted extremely close to one another within a metal frame. The barometric scale is applied to the inner side of one plate, while the other serves to create an impression of lightness and transparency instead of a solid metal backing or enclosed dial. The movement in these instruments is skillfully concealed either within the stem or base of the instrument, or remains hidden behind the rear glass, creating the illusion that the mechanism is absent — or at the very least visually secondary — while the eye is drawn toward the transparent scales themselves. This construction combines the aesthetics of Art Deco with the character of a scientific curiosity: the instrument resembles an elegant interior sculpture, giving it an almost mystical quality.
The earliest documented example of such a “mysterious” barometer originates in France. Antoine Redier, the celebrated clockmaker and inventor, had already produced by the 1890s a table barometer with a concealed transmission system, in which the movement was hidden inside the stem while the displacement of the aneroid capsule under atmospheric pressure was transferred to the pointer arbor through a rack-and-pinion mechanism.
The culmination of the “Mystérieuse” style is associated with the barometers of Goerz in Berlin. Around 1925, the firm C.P. Goerz introduced a table barometer in which two thick circular glass plates with faceted edges formed the dial assembly, while the scale was applied to the inner side of the rear glass. The movement, concealed within the stem of the instrument, was connected to the hand by means of a fine phosphor-bronze wire. This instrument became emblematic both of the company and of the period itself. Following the death of Carl Goerz and the merger of the company into the Zeiss-Ikon conglomerate in 1926, production of the celebrated instrument continued under Zeiss-Ikon, although with certain modifications to the construction.
By the 1930s, Zeiss models had adopted a distinctly chromed aesthetic. The atmospheric pressure scale was applied to the inner surface of the front glass and arranged in a semi-circular layout, allowing the hand to move in a particularly natural and legible manner. The graduations, numerals, and inscriptions appeared deep black against the matte rear glass and exceptionally sharp in appearance. Furthermore, the pointer itself did not obscure the markings, ensuring highly precise readability.
The London firm Short & Mason, renowned for its meteorological instruments, introduced its own “mystery barometers” during the 1920s, closely following the Goerz design. The case was ebonized, the scale — as customary for this style — was executed on the rear glass disc, and the movement concealed within the base of the instrument. In 1900, the American company Taylor acquired the British firm Short & Mason and subsequently employed similar constructions in its own products.
During the 1930s, the world-famous Swiss firm Jaeger-LeCoultre, under the Jaeger trademark, also produced table barometers featuring dual-glass dials. Today these instruments appear frequently on major auction platforms and in prestigious auction houses. One such example was sold by Christie’s in 2017 for $750 and described as “a circular Jaeger table barometer, circa 1935, brass case, glass dial.” Despite their luxurious finish, these instruments adhered completely to the “mystery” concept: two glass plates with the movement hidden behind the rear glass.
The Stuttgart-based firm Gotthilf Lufft, founded in 1881 and celebrated for its aneroid barometers and meteorological instruments, also offered “glass” models during the mid-twentieth century. Lufft introduced an especially original interpretation of the design, producing not only single-dial versions but also remarkable triple-dial variants in which a hygrometer and thermometer flanked the central barometer, each provided with matching glass panels. Unlike most other barometers of this style, however, the mechanism in Lufft instruments was not concealed but openly displayed, almost as if exhibited within a glass showcase.
The Parisian firm Maxant, founded by Léon Maxant — and notably the company that acquired Redier’s workshop in 1905 — naturally continued the tradition of manufacturing sophisticated barometers. Few firms were more suited to reinterpret the celebrated design. Although the Maxant version is less widely known today than the Jaeger examples, it was executed in the same spirit and with equally careful attention to detail.
Maxant Table Aneroid Barometer
The barometer presented here was manufactured in France during the mid-twentieth century and represents one variation of the so-called “mystery” barometers, inspired by the celebrated transparent barometers of the earlier period. It belongs to that rare category of decorative-engineering aneroids in which the measuring mechanism is deliberately concealed from view, transforming the dial into a spatial glass construction that creates the illusion of a floating pointer suspended within a transparent volume.
The case is executed in brass with a satin gilt-toned finish and constructed according to a strictly geometric composition typical of postwar French decorative modernism. The base takes the form of an elongated rectangular plinth above which rises the circular dial assembly. Owing to this architecture, the instrument is perceived almost as an autonomous sculptural object rather than merely a measuring device. The circular brass bezel possesses a finely profiled rim with several concentric grooves emphasizing the depth of the construction.
The principal feature of the instrument lies in the structure of the dial itself. Mounted parallel to one another within the brass frame are two circular mineral glass plates with faceted edges. Together they form a single transparent volume that simultaneously creates an impression of depth while concealing the constructive arrangement of the instrument. Light passing through the faceted edges produces characteristic internal reflections and visually dissolves the boundary between the front and rear glass, causing the pointer and decorative elements to appear suspended in mid-air.
Applied to the inner side of the front glass is a concentric barometric scale graduated in millimetres of mercury over the range of 680–790 mm. The scale is executed in the characteristic French manner, with dense graduations and large numerals arranged along the inner circle. The outer ring contains an elaborate weather indication system. Unlike most traditional French aneroids, where the term VARIABLE (change) is employed, the central transitional zone here is designated by the word INCERTAIN, emphasizing atmospheric instability and uncertainty. Above it appears the word TENDANCE, accompanied by indications of directional change in the weather — au mauvais and au beau. The remaining meteorological indications are not arranged as a continuous phrase around the circumference but grouped in paired vertical columns:
This arrangement of text creates an unusual visual rhythm and greatly enhances the graphic expressiveness of the dial.
At the centre of the composition appears a large black multi-rayed star, also applied to the front glass. In form it resembles a mariner’s compass rose or a stylized navigational compass — a motif closely connected with the visual language of meteorological and maritime instruments. Owing to the transparency of the dial assembly, the star appears to float within the internal space of the instrument while simultaneously serving as a visual backdrop for the pointer hub.
The indicating hand of the barometer is made of thin blued steel and possesses a characteristic elongated openwork construction that emphasizes the lightness and visually “floating” aesthetic of the instrument. The main body of the hand is distinguished by its deep dark-blue tone, typical of thermally blued steel, while its long indicating tip is highlighted with contrasting white paint. Owing to this treatment, the hand remains clearly legible against the transparent glass dial while simultaneously preserving the overall sense of airiness within the construction.
The form of the hand is asymmetrical: the rear counterbalance section is shaped as an elongated spear-like element terminating in an open rhomboid aperture, whereas the forward section is composed of two diverging slender arms converging at the pale indicating tip. Such geometry corresponds closely to the modernist character of the barometer.
The movement of the barometer is concealed behind a circular brass central block mounted upon the rear glass panel. Here a compact arrangement is employed in which the mechanism is disguised directly within the central portion of the dial. The cylindrical brass housing concealing the movement projects slightly behind the instrument. At the heart of the mechanism lies a small nickel-silver aneroid capsule tensioned by a U-shaped steel spring. Motion is transmitted to the pointer arbor by means of a fusee chain. Despite the miniature scale of the mechanism, the construction demonstrates precise layout and finely executed workmanship.
Overall, this barometer represents a characteristic example of how mid-twentieth-century scientific instrument makers continued to reinterpret the ideas of late Victorian “mystérieuse” constructions, transforming the meteorological instrument into a decorative object possessing an almost illusionistic effect. Leon Maxant succeeded in combining a traditional French aneroid mechanism with the aesthetics of the transparent dial and the geometric language of modernist design, allowing the instrument to function simultaneously as a scientific device, an interior design object, and a remarkable optical-mechanical composition.
Conclusion
The “Mystérieuse” design of aneroid barometers emerged at the turn of the twentieth century, passed through a period of particular popularity during the 1920s–30s among European manufacturers, and continues to fascinate collectors today through its enigmatic character. These instruments embody that rare boundary where engineering precision meets aesthetic intrigue: two seemingly floating glass plates conceal a masterfully hidden mechanism. Despite their comparatively recent origin — from the late nineteenth to the mid-twentieth century — they have already secured a lasting place in the history of scientific antiques as iconic “mysterious” barometers.
