Barometers Realm

This Carved Walnut-Cased Aneroid Barometer by Brauckmann, dating to circa 1875, is housed in an expressive carved case made of walnut — a wood widely used in Germany during the second half of the nineteenth century for instruments intended not only for precision, but also for a strong interior and decorative presence. The barometer dial is hand-signed with the name Fr. Koch of Hildesheim. He was a dealer in optical, mechanical, and meteorological instruments, and most likely acted as a retailer for Brauckmann barometers.

The case is conceived in a rich historicist manner. It is crowned by a substantial crest in the form of a stylised acanthus leaf, rendered in a Neo-Renaissance idiom with a volute-based foundation. From this crest descend carved garlands of leaves and blossoms, flowing downward and embracing the entire silhouette of the instrument. These vegetal motifs create a continuous rhythm, visually linking the upper and lower sections of the case into a unified composition. The lower portion is completed by a denser, almost architectural knot of carving, which visually counterbalances the mass of the central barometric unit.

In the upper part of the case, set within an oval frame, is a mercury thermometer. Its glass capillary, terminating in a characteristic spherical reservoir, is mounted on a plate of opaline glass, providing a soft, diffused background for the scales. The thermometer is graduated in two scales — Réaumur and Celsius — a configuration typical of German instruments of this period, intended for both scientific and domestic use.

The main barometric unit is located in the lower section of the instrument. It is protected by a thick mineral glass with a carefully finished faceted edge, set into a brass bezel. Behind the glass, the distinctive dial of this instrument is fully exposed. The dial is made of cardboard, a material frequently employed in nineteenth-century aneroid barometers due to its dimensional stability and suitability for fine printing.

The dial has a two-ring structure. The outer, primary ring bears textual weather indications in the German, reflecting the traditional qualitative interpretation of atmospheric pressure changes. Superimposed upon it is an inner rotating ring carrying the barometric scale, calibrated in centimetres of mercury over a range of 69–82. This ring allows the user to adjust the scale to local conditions — a detail that underscores the practical orientation of the instrument.

Of particular interest is the presence of the word “meter”, printed twice on the dial outside the scale. This is most likely a reference to the metric system, which came into force in the German Empire on 1 January 1872 under the Reichsgesetz über die Maß- und Gewichtsordnung. Earlier barometers commonly employed scales expressed in inches of mercury, essentially traditional units of length (Zoll) applied to the height of the mercury column.

Especially noteworthy is the so-called “circular” aneroid movement, visible through the open dial and indicative of Brauckmann’s exploration of proprietary mechanical solutions in the field of aneroid systems. The movement is characterised by a circular brass frame, mounted on a base of grey cast iron. At the heart of the mechanism lies a self-elastic aneroid capsule made of a brass alloy. The movement of the capsule’s upper membrane is transmitted to a finely proportioned brass lever via a linkage, pivoted both to the membrane and to the lever itself, ensuring bidirectional transmission of the capsule’s motion. Instead of the conventional counterweight on the main lever, this design employs a small coil spring, bearing against the bridge that supports the pointer arbor. Motion is transmitted to the pointer arbor by a thread, instead of the fusee chain typically used in conventional aneroid mechanisms.

Overall, this barometer represents a rare and compelling synthesis of technical experimentation and richly developed artistic casing, making it not merely a measuring instrument, but a fully realised object of nineteenth-century decorative and applied art.