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A329-26 · Aneroid
c.1880
Object Overview
Floral Cast-Iron Aneroid Barometer is a decorative wall-mounted aneroid barometer manufactured around 1880 by the renowned French clockmaking company Japy Frères, one of Europe's largest manufacturers of clocks and clock movements during the 19th century. The instrument represents an interesting combination of traditional barometric technology, artistic cast-iron work, and decorative techniques characteristic of European applied arts of the Victorian era.
The barometer is executed in a style characteristic of Japy Frères, whose precision mechanical instruments frequently formed part of sophisticated interior decoration. Its elaborate case, intricate floral ornamentation, and carefully designed dial suggest that the instrument may originally have formed part of a decorative set accompanied by a wall clock housed in a matching case. Such coordinated ensembles were popular during the second half of the 19th century, allowing interiors to be furnished in a consistent artistic style. The instrument's association with Japy Frères is further emphasised by the company's distinctive monogram, positioned in the lower part of the dial.
simplex (American)
brass, cardboard, cast iron, glass, steel
The unusual case of the barometer deserves particular attention. At first glance, it appears to be an elaborately carved wooden piece made from dark walnut or oak, resembling the traditional carved cases of Black Forest barometers. In reality, however, the entire decorative structure consists of a single massive cast-iron piece, its surface carefully finished to reproduce the appearance of aged carved wood as convincingly as possible.
This remarkable resemblance was achieved through a combination of artistic and technical methods. First and foremost, the casting itself displays an exceptionally high level of detail: numerous leaf veins, folds in flower petals, recesses, and smooth transitions between ornamental elements create the impression of hand-carved woodwork. Following casting, the surface was given a decorative finish with a dark brown coating intended to imitate stained wood. The deeper areas of the relief acquired an almost black appearance, while the raised surfaces retained warm brown and golden tones. This interplay of light and shadow further emphasises the depth of the ornamentation, creating the illusion of aged, polished wood carving. The true nature of the material is skilfully concealed: only the considerable weight of the instrument and an examination of its reverse reveal unmistakably that the structure is made of metal.
The composition of the case is arranged around the central circular frame of the barometer and consists of symmetrical openwork floral ornamentation. Its upper section is crowned by a large, fully opened rose, modelled in high relief and surrounded by smaller flowers, buds, and leaves. The central flower projects forward, forming the most prominent three-dimensional element of the entire composition. Its multiple layers of petals curl into a characteristic spiral, while the surrounding branches extend outward, gradually merging into the other decorative elements.
On either side of the circular case are large scrolls, or volutes, formed from stylised shoots and acanthus leaves. Their intricate spiral curves lend a sense of movement to the composition and recall motifs associated with Baroque and Rococo ornamentation. The outer edges of the volutes descend gracefully, developing into elongated leaves with curled tips and small spherical projections resembling berries. Thanks to the openwork design, numerous spaces remain between the individual scrolls and branches, lending visual lightness to the otherwise massive cast-iron structure.
Immediately surrounding the barometer is a broad circular frame decorated with small floral motifs, rounded projections, and relief scrollwork. It serves as a visual link between the central measuring instrument and the surrounding ornamentation. In the lower section, the composition concludes with two symmetrically spreading branches bearing large elongated leaves, between which is arranged a small bouquet of flowers and berries. Further below, the branches intertwine to form a decorative knot, from which extend three pointed, leaf-shaped elements with a small spherical finial at the centre. This arrangement gives the entire structure a sense of completeness and emphasises its vertical symmetry.
The barometer itself forms an independent measuring unit housed in a cylindrical brass case, which is fitted into the central opening of the decorative cast-iron structure. At the rear, this case is surrounded by a deep cylindrical metal housing that protects the movement while also providing a mounting recess for the instrument. A metal suspension fitting is positioned at the top of the housing, allowing the barometer to be hung on a wall.
The front of the brass case is fitted with a thin, profiled bezel retaining a flat mineral glass. Made of polished brass, the bezel forms a narrow, bright border that contrasts attractively with the dark surface of the decorative case. Mounted at the centre of the glass is an auxiliary trend-indicating pointer, fitted with a small round knurled knob.
The dial is made of thick cardboard with a smooth, light-coloured surface and is mounted within a brass reflector ring. The inner surface of the ring has a characteristic golden hue and provides a decorative transition between the white dial and the outer brass surround.
The principal feature of the dial is a concentric barometric scale calibrated in millimetres of mercury, covering a range from 690 to 800 mmHg. Numerical markings appear at intervals of 10 mm, with smaller graduations between them allowing intermediate readings to be taken. The scale occupies almost the entire circumference of the dial and is designed for direct reading of atmospheric pressure from the position of the blued-steel indicating hand.
Traditional weather indications, characteristic of 19th-century barometers, are printed around the outer edge of the scale. The inscriptions are in Dutch, indicating that the instrument was intended for the Dutch-speaking market. Arranged consecutively around the dial are the following terms: STORM — storm; V Regen — much rain; R Wind — rain and wind; VERANDERLYK — changeable weather; Mooi W — fine weather; Bestendig — settled weather; and ZEER DROOG — very dry.
These indications represent a traditional qualitative interpretation of atmospheric pressure rather than an independent weather forecast. They refer to the typical weather conditions historically associated with different sections of the barometric scale.
The central area of the dial is decorated with a delicate, symmetrical printed ornamental composition. It consists of a small openwork rosette formed from intertwined scrolls, leaf-shaped elements, and elegant undulating lines. The ornament resembles decorative engraving on metal dials and visually frames the arbor of the main barometric hand. Its fine execution ensures that it does not interfere with the legibility of the readings, while giving the relatively simple cardboard dial a more refined appearance. Beneath the central ornament, towards the lower part of the scale, is a small Japy Frères monogram, while the inscription ANEROID BAROMETER is printed along the bottom edge of the dial.
The instrument is operated by a relatively simple but carefully designed mechanical aneroid movement built around a circular corrugated metal capsule made from a brass alloy. The capsule consists of two thin, elastic diaphragms joined around their circumference, their surfaces formed with numerous concentric corrugations. This configuration increases the flexibility of the sensing element and allows its walls to undergo small axial displacements in response to changes in external atmospheric pressure.
Inside the capsule is a helical spring that provides a counteracting force and prevents the diaphragms from collapsing completely under atmospheric pressure. As pressure increases, the capsule contracts slightly; when pressure decreases, it expands under the combined elasticity of the spring and the diaphragms themselves. These movements are extremely small, so a system of mechanical levers is employed to convert them into a clearly visible angular movement of the indicating hand.
Mounted above the capsule is the main brass lever, incorporating a shaped counterweight and pivoting on a transverse axis supported between centres. The central portion of the lever receives the vertical displacement of the capsule's upper diaphragm and converts it into a small rotational movement. One end of the lever has a broad, shaped form, while the other is connected to the subsequent elements of the transmission mechanism. The shaped construction not only reduces the mass of certain parts of the assembly but also allows the lever's mass to be distributed relative to its pivot axis.
The movement of the main lever is transmitted to a small rotating bell-crank lever, also mounted between centres. A fine fusee chain extends from its vertical arm, connecting the lever system to the pointer arbor. The flexible chain transmission allows small displacements to be transferred with minimal frictional losses and enables the limited movement of the sensing element to be converted into the required angular rotation of the indicating hand.
The chain is kept under tension by a small spiral spring mounted on the pointer arbor, thereby reducing backlash and ensuring coordinated operation of the individual components of the transmission.
This barometer is a particularly expressive example of decorative meteorological instruments from the last quarter of the 19th century. Its most distinctive feature is the unusual combination of materials and artistic techniques: a heavy cast-iron case skilfully imitating carved wood, an elegant brass surround, a Dutch-language dial, and a traditional aneroid movement together form a harmonious and visually coherent composition.
Its association with the renowned French manufacturer Japy Frères, together with its possible original inclusion in a matching decorative set with a clock, adds further historical interest to the instrument. This is not merely a device for measuring atmospheric pressure, but also a characteristic object of 19th-century European material culture, reflecting a period when scientific instruments increasingly became an integral part of the artistic decoration of domestic interiors.