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Object Overview
We are presented with a Tremeschini Pocket Barometer, dating approximately to around 1900, associated with the French engineer-designer Antoine Tremeschini, whose authorship is confirmed by the maker’s mark on the dial. The instrument survives together with its original protective case made of burgundy leatherette with a soft crimson velvet lining; the case is fitted with a brass clasp engraved “L.Z.”, referring to a Parisian manufacturer of fittings and not related to the instrument itself.
Case Construction
The barometer case is made of nickel-plated brass and has a compact circular form typical of portable instruments of the late 19th century. At the top is a small suspension element—a ring mounted on a swivel joint—allowing the instrument to be worn on a chain or secured in field conditions.
The case consists of three main parts:
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Tremeschini
brass, cardboard, glass, nickel plating, nickel silver, steel
This construction combines compactness, serviceability, and adequate mechanical protection—essential qualities for a pocket instrument. However, even such a small notch in the rear cover increases the risk of dust and small insects entering the mechanism and reduces resistance to moisture.
Dial and Scales
Particular attention should be paid to the dial, which, unlike the traditional materials used in portable barometers—silvered brass, enamel, or porcelain—is made of dense cardboard, more typical of wall-mounted instruments.
The dial consists of two elements:
This solution is unconventional. In most pocket barometers, this area is occupied by a movable altitude scale, conveniently adjusted by rotating the bezel. In this case, however, rotating the bezel with weather terms can be misleading: the position of the inscriptions shifts relative to the pointer and the trend indicator. When setting the current pressure or altitude, the weather terms are displaced, indicating irrelevant conditions. It should also be noted that such textual weather indications are inherently approximate and were often retained more as a traditional decorative feature than as an accurate forecasting tool.
The central area of the main disc is decorated with an elegant ornamental motif—a finely printed composition of vegetal scrolls characteristic of late 19th-century French instrument graphics, lending the instrument a distinct decorative completeness.
The barometric scale is arranged concentrically along the outer circumference of the dial and is calibrated in centimetres of mercury in the range of 62 to 79 cm.
Within it lies a nonlinear altitude scale, calibrated in metres from –200 to +1600 m. This configuration reflects the practical use of the instrument as a barometric altimeter, particularly in travel and mountaineering.
Readings are indicated by a refined steel hand, oxidized to a deep blue through thermal bluing; the pointer features delicate feathering and resembles an arrow.
Typography of Weather Terms
Special attention should be given to the typographic treatment of the weather indications applied to the narrow cardboard scale in the bezel. Here, three distinct graphic styles are used deliberately, each differing in form and carrying its own visual “intonation” that reinforces the meaning of the term.
“VARIABLE” — decorative display typeface. The word VARIABLE is rendered in the most expressive and ornamental style. This is a display typeface with pronounced engraved characteristics:
This style is close to Victorian display types of the second half of the 19th century and is used intentionally: variable represents the most uncertain and dynamic weather condition, and its graphic form emphasizes this instability.
“TEMPÊTE”, “TRÈS SEC” — strict high-contrast serif with decorative shading. These terms are executed in a more structured and “engineered” manner. The typeface is a high-contrast serif with internal line shading:
This treatment is typical of engraved instrument dials of the late 19th century, where legibility was combined with decorative refinement. It is particularly appropriate here: tempête (storm) and très sec (very dry) denote extreme conditions, and their typography becomes more disciplined and technical.
“PLUIE OU VENT”, “BEAU TEMPS” — classical serif typeface. The third type is the most restrained and functional, used for intermediate or common conditions:
Here, a classical serif is employed:
Abbreviations appear in the weather terms as a direct consequence of limited space on the scale. These abbreviations are executed carefully and preserve clarity of meaning, reflecting a well-considered layout.
Movement
The instrument is based on an aneroid mechanism built around a capsule approximately 30 mm in diameter, made of nickel silver and equipped with an internal helical spring.
The deformation of the upper membrane under atmospheric pressure is transmitted via a tiny pushrod soldered to its surface to the rocker of the main lever, which features a characteristic tulip-shaped counterweight. The free end of this lever rests upon a rotating crank lever on the main arbor, from which motion is transmitted via a fusee chain to the pointer arbor, driving the indicating hand.
A notable constructional feature is the placement of the main arbor: it is mounted on the reverse side of the brass main frame and becomes visible when the rear cover is removed.
Calibration is performed by means of an adjustment screw accessible through an opening in the back of the case. Turning this screw raises or lowers the entire mounting plate carrying the mechanism components, including the rocker and pointer arbor, thereby allowing correction of the instrument’s readings.
Conclusion
The present pocket barometer represents a compelling example of a transitional stage in the development of portable aneroid instruments, where mechanical ingenuity is combined with experimentation in the visual presentation of data. Its construction reflects the mature mechanics of late 19th-century aneroid systems, while the unusual cardboard dial solution demonstrates an exploratory approach to scale layout and indication.
Taken as a whole—from the precise kinematics of the movement to the decorative graphic design of the dial and the original case—the instrument embodies a characteristic idea of its time: the unification of accurate measurement, portability, and aesthetic refinement within a single compact object.