Silver pocket barometer having 2⅜” silvered and engraved dial, the outer altimetric scale calibrated in feet with a range from 0 – 5000ft, divided to 100ft. Inner barometric scale calibrated in inches of mercury with a range from 26” – 31” and divided to 1/10^th”, the upper part with standard meteorological terms, signed by the maker “F. Barker & Son, Makers, London,” the lower part with Bourdon type thermometer marked “Impd Pat No 7318,” calibrated in degrees Fahrenheit with a range from 30° – 140°. Blued steel pointers, crown driven point index, bevelled glass. Conventional improved Vidi pattern movement, dated “3/09,” driven from a single capsule and tensioned on a C spring, contained within a silver barrel form case, the engine turned verso with a central cartouche engraved with an armorial crest, maker’s mark “FB & S Ltd” and hallmarks for sterling silver, London, and 1909. The crown stem with substantial suspension ring also hallmarked.

All contained within its original leather over timber blue silk and velvet lined case, snap closure on a button release.

Condition: The subject of a full service, conservation and calibration under laboratory conditions, see performance chart. The barometer extremely accurate across and below the standard barometric range, accuracy diminishing at lower pressures consistent with age and design. The thermometer responding to rising temperature. Fine, crisp overall, the case with external losses and signs of repair to leather at release button, marks and abrasions, general signs of wear. The lid silk replaced with a period piece, the velvet lining with wear and losses to upper edge, otherwise good.

Comments: Extremely unusual and of very high quality, instruments such as this with integral Bourdon thermometers may be considered very rare.

Very much one for the collector.