Barometers Realm

This barometer is part of the private collection of our friend and fellow collector Heikki Vähäsarja (Finland). All photographs were kindly provided by him.

This Copenhagen Wall Aneroid Barometer, dating from approximately 1890, is an elegant wall-mounted aneroid barometer signed by H. E. Holst, Kiøbenhavn—one of Copenhagen’s best-known firms of the second half of the nineteenth century, specializing in the sale of navigational, scientific, and meteorological instruments. Despite its relatively restrained appearance, the instrument is a fine representative of high-quality domestic aneroid barometers of the late nineteenth century, combining refined craftsmanship with precision mechanics and a construction typical of its period.

The case is formed as a circular solid wooden frame with carefully profiled concentric mouldings that create a distinctive interplay of light and shadow. The wood has been meticulously polished and finished with a clear varnish that enhances its natural grain and warm reddish-brown colour. At the top of the case is a metal hanging loop intended for wall mounting.

The dial is protected by a substantial brass bezel fitted with a flat mineral glass. Mounted at the centre of the glass is the traditional set pointer, operated by an external knurled knob that allows it to be positioned manually opposite the indicating pointer. This arrangement enabled the user to observe changes in atmospheric pressure over time without having to remember the instrument’s previous reading.

The dial itself is made of heavy white card and features an exceptionally clean and highly legible layout. Its concentric barometric scale is calibrated in Paris inches of mercury, covering a range from 26 to 30 inches. Around the outer circumference are the traditional Danish weather indications describing the expected weather conditions associated with various barometric pressures. The lower part of the dial bears the French inscription Baromètre Holostérique, emphasizing that the instrument belongs to the family of aneroid barometers operating without the use of a liquid mercury column.

The indicating pointer is made of blued steel and exhibits the delicate openwork form characteristic of instruments of this period, complete with a decorative crescent-shaped counterweight. Owing to its minimal mass and high rigidity, this design reduces the inertia of the moving system and contributes to a more accurate indication of atmospheric pressure changes.

At the heart of the measuring mechanism is an evacuated brass aneroid capsule, incorporating an internal coil spring that prevents the capsule from collapsing completely under atmospheric pressure while defining its operating characteristics. As atmospheric pressure changes, the upper wall of the capsule undergoes very slight vertical movement, which is transmitted via a short pushrod to a long brass lever fitted with a spherical counterweight. This counterweight balances the moving system, reducing the influence of the mechanism’s own weight on the sensitive element while ensuring smoother transmission of motion.

From the principal lever, the movement is transferred to a compact bell-crank lever rotating on carefully manufactured pivot bearings with minimal friction. At this stage, the minute displacement of the aneroid capsule is amplified further before being transmitted by means of a fusee chain to the pointer arbor. This arrangement, representing one of the most refined kinematic systems employed in early aneroid barometers, provides substantial amplification of the capsule’s movement while maintaining exceptional accuracy and smoothness of pointer motion.

Thanks to the flexible fusee chain, lateral loads on the pointer arbor are almost completely eliminated, friction within the mechanism is significantly reduced, and the minute movements of the aneroid capsule are transformed into the smooth and precise rotation of the indicating pointer with remarkable efficiency.

This instrument is an outstanding example of a late nineteenth-century Northern European aneroid barometer, in which elegant external design is harmoniously combined with a thoughtfully engineered and finely executed mechanical construction. The noble materials, classical case architecture, refined dial, and carefully crafted fusee-chain movement make it not only a reliable meteorological instrument of its era but also an impressive testament to the high standard of Danish instrument making and the culture of precision engineering at the close of the nineteenth century.