Barometers Realm

Before us is the Mayak Desk Clock with Barometer and Thermometer — a balance-driven mechanical desk clock with an integrated barometer and thermometer, produced around 1990 by the Serdobsk Clock Factory in Penza Oblast. The Serdobsk Clock Factory was one of the principal Soviet manufacturers of domestic interior clocks. This instrument clearly reflects a new stage in the development of the Mayak brand: it is no longer merely a desk clock, but a compact domestic weather station intended for a writing desk, sideboard, shelf, or study interior.

Externally, the instrument has a strict rectangular case of horizontal format. The case is wooden, veneered with sliced decorative veneer of hardwood species. This finish gives the object a warmer, more “furniture-like” character: the clock appears as part of the domestic interior of the late Soviet period. Its straight edges, moderately projecting depth, and warm brown veneer tone bring it close in spirit to desk radios, small pieces of furniture, and cabinet souvenirs of the same period. The case stands on two small black plastic feet, which visually separate it from the table surface and slightly raise the front plane.

At the front is a rectangular protective mineral glass. It is set into a chromed rectangular bezel surrounding the entire dial panel. The chromed frame creates a contrast typical of late-Soviet interior instruments: the warm wooden case against the originally white dial. An interesting feature of this particular example is the preserved presentation inscription on the glass, made on the occasion of a wedding. It transforms a serial factory-made object into an item with a personal biography: the clock no longer merely represents the production of the Serdobsk Clock Factory, but also preserves the memory of a particular family event — a gift presented to newlyweds and then living with them through part of their domestic history.

At the rear, the case is closed by a brown-painted steel plate. This back plate contains functional cut-outs and control elements. Through the central openings one can access the winding key and the knurled knob for setting the time. In addition to these, the rear panel has two small windows covered by steel plates. One gives access to the calibration screw of the barometer, allowing the reading to be corrected according to altitude and actual atmospheric pressure; the other gives access to the rate regulator of the clock movement, that is, the “faster–slower” adjustment. This rear arrangement clearly reveals the practical nature of the instrument.

The dial is a common front panel for all three instruments: the clock, the thermometer, and the barometer. It is made of plastic; originally its surface was white or light cream, but over time, under the influence of light and material ageing, it has acquired a warm yellowish tone. Today this yellowing is perceived as part of the historical texture of the object: it softens the graphics, makes the front panel less cold, and gives the instrument the characteristic late-Soviet domestic patina.

The left part of the dial is occupied by the time scale. It is formed by large Roman numerals arranged in a circle with a noticeable inclination and decorative freedom. The use of a Roman scale gives the instrument a more solemn, almost presentation-like character. The numerals are embossed: they are raised above the dial plate and painted black, and thanks to this relief they remain clearly legible against the cream-coloured background. The hands are dark and contrasting, with the decorative form characteristic of Mayak: the minute hand is long and tapers towards its end, while the hour hand is shorter and provided with a circular ring near its base. This motif evokes a distant association with Breguet-type hands, but in a more simplified, Soviet, and technologically adapted form.

The right sector of the dial is occupied by the meteorological section. In the upper right zone is a mercury thermometer with a Celsius scale applied directly to the plastic surface of the dial. The scale is marked symmetrically on both sides of the capillary and is intended for the ordinary domestic temperature range.

In the lower right part is the barometric scale, which has no numerical units of measurement. It is provided only with textual weather indications: “Пасмурно” (“overcast”) on the left, “Переменно” (“changeable”) in the centre, and “Солнечно” (“sunny”) on the right. Between these words is an empirical scale with frequent divisions, serving more of a decorative and orienting function than a precise measuring one. Such a scale is not intended for exact reading of atmospheric pressure; it turns the barometer into a domestic indicator of the weather’s mood. The user does not see millimetres of mercury, but a simple and intelligible household formula: a tendency towards overcast or sunny weather.

At the lower part of the chromed bezel, in a small cut-out, there is a plastic wheel controlling the barometer’s trend-indicator hand. This reference hand is intended for manual setting relative to the current position of the main barometric hand. In this instrument, the tip of the reference hand is green, while the tip of the main pointer is red. This allowed the owner to compare two fine hands visually: one showed the present position of the barometer, while the other preserved the previous mark, making it possible to observe whether the tendency was moving towards “overcast” or towards “sunny”.

The clock movement has an auxiliary escapement regulator with a lever escapement, a screwless balance on 11 jewels, and a spring motor without a barrel. Technically, it is a class 0 movement: the average daily rate does not exceed 50 seconds, the running duration from one full winding is not less than 9 days, and the average service life is not less than 10 years. The use of a balance regulator instead of a pendulum allowed the clock to be used in desk format without the need for strictly vertical positioning. This was an important consumer advantage: the instrument could be placed on a desk, shelf, or sideboard, moved slightly, and it would continue to run independently of the precision of its suspension. The clock movement is still in impeccable condition and fully functional.

The barometric mechanism is especially interesting. It is based on a pointer drive using a torsion strip — that is, a flat strip twisted like a screw. One flat strip here performs the work of three separate components of a classical aneroid: it converts linear motion into rotation, serves as the axis of the pointer, and returns the pointer by itself, effectively taking on the role of a spiral spring. In an ordinary aneroid barometer, these functions are distributed between an external spring tensioning the aneroid capsule, a system of levers, the pointer axis, a toothed sector or fusee chain, and a separate return spring. Here, most of this kinematic chain is replaced by a single tensioned and pre-twisted strip.

The torsion strip is twisted into the form of two opposing spirals: the upper half is twisted “to the right”, the lower half “to the left”. Each half forms approximately four turns, about eight turns in total, while in the middle the two parts meet in a kind of “node”. Both ends of the strip are fixed so that they cannot rotate freely; the whole strip is held in longitudinal tension. Attached to the central part of the strip is a light yoke-like half-arc carrying the barometer pointer. When the strip, under the effect of a change in force, slightly twists or untwists, its centre rotates around the longitudinal axis; together with it, the yoke and pointer move the indicator along the barometric scale.

This torsion-strip principle is valued in measuring technology primarily for the absence of bearing friction and for good repeatability. In precision instruments it is known as a taut-band or tension-band suspension. It is curious to see this idea in a “popular” implementation — not in a laboratory galvanometer or a precision pointer instrument, but in a mass-produced domestic clock from the Serdobsk factory. Here, a high-precision measuring principle is reduced to the cheapest possible, yet still ingenious, construction for a household barometer.

At the heart of the mechanism is an aneroid capsule with concentric annular corrugations. These corrugations are not decorative. They increase the effective compliant area of the diaphragm and make its deflection larger and, within certain limits, more linear. The capsule is made of beryllium bronze, a material well suited to elastic sensing elements. Beryllium bronze has a high elastic limit, relatively low hysteresis, and can undergo precipitation hardening to stabilise its elastic properties. In this case, the capsule is self-springing: there is a partial vacuum inside it, and the restoring force is provided by the wall of the corrugated diaphragm itself. It therefore needs neither an external C-shaped spring nor an internal helical spring to support the capsule walls.

The aneroid capsule is mounted on a cast aluminium frame, which serves as the load-bearing base of the entire barometric unit. It is the capsule that changes the tension of the torsion strip under the action of atmospheric pressure. When the pressure changes, the axial force applied to the strip also changes; both halves of the strip tend to “unwind” slightly, and because they are twisted towards each other, their unwinding turns the centre in the same direction. The rotations add together rather than cancel each other out. When the tension decreases, the centre of the strip turns back. The restoring torque is created by the elasticity of the strip itself — by both torsion and extension.

A classical aneroid has an extremely small capsule travel and therefore has to use a mechanical multiplier of approximately ×10–15: a main lever, a crankshaft, a fusee chain, a pointer arbor, and a separate hairspring to take up play and return the hand. Here the designer has essentially removed all of this. The strip itself provides amplification through the geometry of its twist, supplies the elastic return, and serves as the pointer axis. This does not mean that the mechanism is more accurate than a classical aneroid; on the contrary, it is simpler and cruder. But as a mass-engineering solution it is exceptionally revealing: a minimum of parts, a minimum of friction, and a minimum of assembly operations.

On the reverse side of the aluminium frame one can see a steel element with a vertical slot, along which slides a red knurled disc with a small screw at its centre. This is the unit through which the travel of the capsule is converted into a change in the tension or position of one end of the torsion strip. The tiny slotted screw in the centre serves as the anchoring point for one end of the strip and, at the same time, as the zero-setting adjustment. By turning it, the factory technician set the pointer to a conventional “average” pressure; the user, in turn, could correct the reading when the installation altitude changed or when comparing the instrument with a more accurate barometer.

Overall, this Mayak desk clock with barometer and thermometer is an expressive example of late-Soviet domestic engineering in a more decorative, presentation-oriented interior form. The veneered wooden case, chromed frame, yellowed plastic front panel, Roman hour scale, mercury thermometer, and barometer without numerical calibration create the image not of a strict scientific instrument, but of a domestic weather station intended for everyday life. Yet behind its external simplicity lies a very curious mechanism: a weekly balance-driven clock and an aneroid barometer with a torsion-strip transmission, in which engineering economy is brought almost to the point of elegance. This is not an instrument of laboratory precision, but of domestic observation — an object that shows not only time and temperature, but also the late-Soviet idea of technical comfort itself.