Barometers Realm

This Pocket Barometer with Revolving Altitude Scale, dating from approximately 1890, is a fine example of a late nineteenth-century pocket aneroid barometer manufactured by the renowned French firm Richard Frères, one of Europe’s leading producers of precision meteorological instruments. Designed for travellers, mountaineers, engineers, and military officers, this compact instrument combines the functions of a highly accurate barometer and a portable altimeter within an elegant case of exceptional quality, reflecting the technical sophistication for which the House of Richard became internationally renowned.

The instrument is housed in a compact circular case manufactured from gilt brass, whose finely finished surfaces and restrained proportions give it both elegance and durability. Around the circumference runs a finely knurled edge that provides a secure grip during operation, while at the top is a substantial brass suspension ring, allowing the instrument to be carried on a chain or attached to a belt, pocket watch fob, or field equipment.

The front of the instrument is fitted with a revolving knurled bezel, rotating smoothly around the case. Mounted within the bezel is a flat mineral glass, while the inner circumference of the bezel carries a finely engraved altitude scale on a silvered brass ring. This revolving altitude scale is calibrated in metres, extending to 4,000 metres, and enables the user to determine elevation by rotating the bezel until the current atmospheric pressure reading corresponds with a known reference pressure. This ingenious arrangement transformed the barometer into a practical pocket altimeter without requiring any additional mechanisms.

The dial is likewise manufactured from silvered brass and features a refined concentric layout characteristic of Richard Frères instruments. The principal barometric scale is calibrated in centimetres of mercury, covering a range from 50 to 78 centimetres. Rather than employing the traditional sequence of numerous weather indications, the scale is marked with only two concise French terms—PLUIE and BEAU—indicating the general tendency toward unsettled or fair weather. This restrained design places emphasis on the numerical pressure readings while still providing immediate qualitative interpretation.

The indicating pointer is made of blued steel and exhibits the elegant form typical of high-grade French barometers of the period. Its rear section terminates in a graceful crescent-shaped counterweight, balancing the moving system while lending the instrument a refined visual character.

The barometer is preserved within its original protective carrying case, whose interior is lined with richly coloured crimson velvet supporting the instrument, while the inside of the lid is covered with matching red silk. Besides protecting the delicate mechanism from shocks and dust during transport, the luxurious lining reflects the high-quality presentation expected of precision scientific instruments intended for discerning professional and private clients.

At the heart of the instrument lies the characteristic Richard Frères movement, widely employed in the firm’s pocket barometers and altimeters throughout the late nineteenth century. Its sensitive element consists of a nickel silver aneroid capsule measuring approximately 25 millimetres in diameter. Although remarkably compact, the capsule provides excellent sensitivity and forms the foundation of the instrument’s measuring system.

The capsule is tensioned against an external coil spring by means of a substantial operating lever. This spring establishes the operating characteristics of the sensitive element while ensuring its stable return movement as atmospheric pressure changes.

At the end of the principal lever is a small hardened pushrod, which acts upon a miniature bell-crank lever mounted on finely made pivot bearings. The vertical arm of this tiny lever drives a toothed rack, which meshes directly with a precision-cut pinion mounted on the pointer arbor. This rack-and-pinion transmission converts the minute linear displacement of the aneroid capsule into the smooth rotary motion of the indicating pointer while maintaining high mechanical efficiency and excellent repeatability.

The overall construction of the movement demonstrates the remarkable degree of miniaturisation achieved by Richard Frères. Within a movement scarcely larger than a pocket watch mechanism, the designers succeeded in incorporating an aneroid capsule, spring compensation, a multi-stage transmission, and an integrated altitude-reading system without compromising either accuracy or robustness. Every component reflects careful engineering and the refined mechanical workmanship that established Richard Frères as one of the foremost manufacturers of portable meteorological instruments during the nineteenth century.

This instrument is an outstanding example of a late nineteenth-century French pocket barometer, combining elegant craftsmanship with sophisticated engineering in an exceptionally compact form. Its revolving altitude scale, silvered dial, finely executed Richard Frères movement, and luxurious original presentation case make it not only a highly practical scientific instrument, but also a remarkable testament to the golden age of precision portable meteorological instrumentation.