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Object Overview
This Barrel-cased pocket barometer, manufactured by the French company PNHB around 1880 for the Berlin optical firm Paetz & Flohr, represents a striking example of high-grade European instrument making of the late nineteenth century, combining refined engineering with a compact form intended for personal use.
The barometer is housed in a characteristically barrel-shaped brass case. Its proportions are carefully balanced: sufficiently massive to protect the mechanism, yet still comfortable for carrying in a pocket or travel case.
A thin, rotating, knurled brass bezel retains a flat mineral glass with a neatly executed faceted edge. The bezel is distinguished by its exceptional delicacy—it is noticeably thinner than those found on most contemporary pocket aneroids—and carries a slender reflective brass ring that visually expands the scale. Mounted on this reflective ring is a small brass rod serving as a trend indicator, allowing the user, by rotating the bezel, to mark a previous pressure reading.
On the rear wall of the case, precisely centered, is a circular PNHB logo stamped into the metal. This mark functions not only as a manufacturer’s identification but also as a form of quality assurance characteristic of the company’s output.
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aneroid capsule tensioned on a C-spring
brass, cast iron, glass, nickel silver, silvered brass, steel
The dial is made of silvered brass and has a cylindrical form that fully corresponds to the geometry of the case. Its height is nearly equal to that of the case itself, allowing the dial to be inserted fully into the housing until it seats at the bottom, creating the impression of a single continuous metallic volume—a rare and technically demanding solution for pocket instruments.
The dial carries two concentric scales. The inner barometric scale, calibrated in centimeters of mercury over a range of 59–78 cm, is laid out linearly, with evenly spaced divisions and high engraving precision. The outer altitude scale, positioned beyond the main scale, is non-linear and calibrated in meters, ranging from –300 to 2000 m, reflecting the relationship between atmospheric pressure and elevation above sea level.
Notably absent are any conventional textual weather indications. The only inscription on the dial is “Holosteric barometer”, directly referencing PNHB’s aneroid technology and emphasizing the scientific rather than decorative character of the instrument.
The indicating hand is made of heat-blued steel and features a distinctive form with a crescent-shaped tail, lending visual elegance while simultaneously reducing visual weight over the scale.
The internal movement has the immediately recognizable architecture of PNHB and represents a miniaturized version of the mechanisms used by the company in their wall-mounted aneroid barometers.
The sensitive aneroid capsule, made of nickel silver, is tensioned by a C-shaped steel spring fixed to a substantial lever resting in two brass supports. In the original design, motion was transmitted to the pointer arbor by means of a fusee chain; however, in this particular example, clear traces of repeated intervention in the mechanism are visible—most likely the result of multiple episodes of damage during the barometer’s working life. At present, the fusee chain has been replaced by a simple thread, a telling sign of the instrument’s long and active use.
This PNHB pocket barometer made for Paetz & Flohr is not merely a measuring device, but a concentrated expression of late nineteenth-century engineering culture. It unites scientific rigor, refined mechanics, and tangible traces of lived history—from precise aneroid solutions to later repair interventions. Such instruments once accompanied travelers, engineers, and scientists, and today remain rare and valuable witnesses to an era in which the accurate measurement of the atmosphere became part of personal human experience.