Barometers Realm

Before us is a Nickel-Plated Brass Desk Barometer, dating to approximately 1910, manufactured by the French maker Victor Reclus and intended for the Swedish market, as clearly indicated by the localized scale with weather terms in Swedish.

The case has a compact cylindrical form and is made of nickel-plated brass, giving it a characteristic soft silvery sheen with a light patina of age. The construction is designed for desk use: small brass feet are fitted underneath to ensure stable positioning. The front is framed by a thin bezel holding a flat mineral glass. At the center of the glass is a brass trend pointer, fitted with a knurled knob that allows manual adjustment for tracking changes in pressure.

The dial is made of card and left open in the central section, allowing a direct view of the aneroid capsule and transmission mechanism. It is set within a nickel-plated reflective ring, enhancing legibility through increased contrast. The barometric scale is arranged concentrically and graduated in millimetres of mercury, ranging from 690 to 800 mmHg, in accordance with the European metric system. The scale is further annotated with Swedish weather terms, reflecting the instrument’s adaptation for a Northern European user.

At the lower part of the dial appears the inscription “Aneroid Barometer,” along with the Victor Reclus trademark — the letter “R” enclosed within a diamond, serving as a distinctive maker’s mark.

The open dial design allows a view into the interior of the instrument, where the unique rackless movement of the barometer is visible.

Immediately behind the indicator hand, a brass bar is visible, secured with two screws to its supports. This bar holds the entire pointer shaft, which is surrounded by a small helical spring. A linked chain is wound around the pointer shaft and extends downward, attached to a thin steel rod, which we will return to later.

Looking deeper inside, we see a wide horizontal brass plate—the main bracket—resting on supports fixed to the main frame. Beneath this main bracket, between two holders, a delicate brass rocker arm is mounted transversely. The upper part of this rocker arm forms an unusual shape and acts as a counterweight, while the lower straight section extends into a long lever, ending in a pressing arm shaped like an arrow pointing upward.

The tip of this pressing arm is inserted into a round hole in the main lever, but its tail end is directed downward at a right angle to the lower plate, freely resting (without any attachment) on a small angular lever. The plate with the angular lever, like the rocker arm, pivots between two holders.

Completing the closed-loop movement transmission, another lever extends upward from this plate and connects to the previously mentioned steel rod and chain, leading to the pointer shaft.

But how does the initial movement of the aneroid capsule walls reach the rocker arm? Typically, a tiny pusher soldered to the upper sensitive chamber wall is used to transfer this initial weak motion to the rocker arm for further amplification.

In this case, however, a small screw is used, clearly visible through the dial, positioned slightly above the pointer shaft. This screw is inserted into the base of the rocker arm’s counterweight, pressing down onto the aneroid capsule. This provides an additional adjustment feature. It is through this screw that the initial movement of the sensitive chamber walls is transmitted to the pivoting rocker arm, which then acts as a long lever, freely pressing from below on the angular lever of the oscillating plate. The movement is then transferred to the vertical lever, which is connected to the steel rod and chain, ultimately rotating the pointer shaft.

The final element of the construction—the sensitive aneroid capsule by Vidie, 45 millimeters in diameter—features a noticeable elevation at the center, devoid of the usual corrugated structure. Inside the capsule, there is a built-in helical spring, preventing the collapse of the chamber walls under atmospheric pressure.

How is the standard aneroid barometer hand calibration performed in this case? On the back surface of the instrument, there is a calibration hole containing an adjustment screw. However, the method used in this barometer breaks all conventions.

The reason is that the supports for the plate with the angular and vertical levers, where it pivots between its holders, are not positioned on the main frame as usual. Instead, they rest on a long flat steel plate, which is itself attached to the base of the aneroid chamber and slightly extends beyond its diameter on one side.

Through the main frame, a screw is inserted, with its sharp tip pressing against this steel plate. By turning the screw, one can influence the entire plate, raising or lowering it. This, in turn, raises or lowers all the crucial movable lever connections positioned on the edge of this plate.

Overall, this instrument represents a fine example of an early 20th-century French export aneroid, combining restrained industrial aesthetics, an openly displayed mechanism, and thoughtful regional adaptation, making it not only a measuring device but also an object with a clearly defined cultural identity.