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hygroscopicity
glass, hair, nickel-plated brass, steel
Presented here is a Pocket hygrometer manufactured by the German company Lambrecht, dating to approximately 1950. The instrument belongs to the already industrial phase of the firm’s development, yet retains a classical mechanical foundation, in which measurement is carried out by a proprietary sensitive element — treated hair, assembled into a multi-strand bundle and calibrated by the manufacturer. This element bears the trade name “Pernix” and is protected by a German patent (D.B.P. — Deutsches Bundespatent).
Structurally, the instrument represents an almost laboratory-grade measuring mechanism enclosed within a compact portable case, making it a characteristic example of high-quality field instruments of the mid-20th century. Hygrometers of this type were intended for specialists operating outside stationary environments — meteorologists, engineers, surveyors — as well as for industrial and scientific applications.
Case Construction
The instrument features a pocket-sized case of approximately 50 mm in diameter, manufactured from nickel-plated brass, providing both corrosion resistance and a distinctive cool, mirror-like finish.
Particularly noteworthy is an ingenious design solution: the outer ring, which encircles the case and forms a suspension loop at the top for attachment to a chain, is a movable element. It can be released from the case and unfolded on hinges, transforming into an elegant integrated stand. This allows the instrument to be placed on a horizontal surface. The solution is at once simple and inventive, executed to an exceptionally high standard.
At the top of the case is a knurled crown, resembling that of a watch. Its function, however, is entirely different: when rotated, it opens and closes ventilation shutters located on the rear of the case. In the open position, free access of ambient air to the sensitive element is ensured, which is essential for accurate measurement of relative humidity. When closed, the mechanism is protected from dust, contamination, and excess moisture. This feature demonstrates both thoughtful design and a high level of engineering refinement.
The hygrometer is supplied with a protective leather case, embossed with the manufacturer’s logo. Inside, a rigid wooden insert (palette), lined with burgundy velvet, provides structural support and protects the instrument from mechanical damage.
Dial
The dial is made as a metal plate with an industrial enamel-like lacquer coating, bearing a printed non-linear scale of relative humidity from 0 to 100%.
At the top is the Lambrecht logo — interlaced letters W (Wilhelm) and L (Lambrecht) enclosed within a stylized trapezoidal frame. Below the scale appears the designation of measurement units — percent relative humidity (% rel. Feuchte).
In the lower portion, arranged in a semicircle, is the inscription Lambrecht Hygrometer, identifying the instrument type, and beneath it the marking “Pernix” D.B.P., referring to the proprietary sensing element and its patent protection in Germany.
Operating Principle and Sensitive Element
The sensitive element of the hygrometer consists of a bundle of specially treated hair, whose longitudinal changes in length are transmitted through a system of levers to the pointer mechanism.
For example, a reading of 60% relative humidity indicates that the amount of water vapor in the air corresponds to 60% of the maximum possible content at a given temperature.
The proprietary “Pernix” element is distinguished by its high sensitivity and was used in cases where rapid response to changes in humidity was required, as well as for monitoring low humidity levels at low temperatures. For optimal performance, such systems require adequate ventilation, which explains the presence of the adjustable shutter mechanism.
Structurally, the sensitive element consists of a bundle of dozens of fine hair strands, stretched in parallel and secured at both ends. In the central region, they are combined to transmit force to the mechanism. The use of a bundle rather than a single hair allows:
The hair undergoes special treatment — degreasing, stabilization, and calibration — ensuring predictable dimensional changes in response to humidity variations.
The construction also incorporates a spiral spring (hair spring), which performs several functions simultaneously:
Taken together, this represents a high-quality industrial realization of the classical hair hygrometer, brought to a high level of engineering refinement.
Conclusion
The Lambrecht hygrometer demonstrates an exceptionally high level of craftsmanship and attention to detail, characteristic of the German instrument-making tradition of the mid-20th century. Its unique form factor — incorporating an integrated stand, adjustable ventilation system, protective leather case, and the possibility of fine calibration — makes it not only a functional device but also an object of considerable engineering elegance.
The use of the Pernix technology, combined with the carefully considered arrangement of the sensitive elements within such a compact case, reflects a clear pursuit of both portability and precision.
This instrument stands as a rare example of the harmonious union of two qualities — elegance of design and high accuracy of measurement, where the aesthetics of form directly follow the engineering logic of the device.
