Pocket barometer with 2½” silvered dial having a barometric range from 23–31 inches of mercury, the upper portion annotated “Stormy,” “Rain,” “Change,” and “Fair,” and signed by the maker “Negretti & Zambra.” The lower portion marked “London” with the serial number “1106.” Blued-steel pointer and gilt brass telltale with setting wheel, bevelled glass. Heavy drum case, the verso with inscription “F. Pocklington.” Port with calibration screw set at 3 o’clock. All contained within its original burgundy Moroccan leather over wood green velvet and silk lined case, the lid with maker’s cartouche in gold block.
Surviving in exceptional condition, the case retaining much original lacquer. The leather case retaining much original colour and lustre – a small hole has been drilled to the rear centre, possibly to fix the case to an object or mistakenly to allow the changing pressure to act on the movement! Showing excellent function with smooth progression and good sensitivity.
Now very scarce, these instruments were pre-eminent circa 1860, having been reduced in diameter from the earlier 4½” dial instruments. The new much reduced instrument was produced at the behest of Admiral Fitzroy who, upon the the expiration of the Vidi patent on aneroid barometers, commissioned Negretti & Zambra to not only produce a more portable barometer, but to improve its mechanical arrangement and temperature compensation (see Negretti & Zambra, A Treatise on Metrological Instruments, Chapter V: Secondary Instruments, item 49 and accompanying Fig. 34). This particular instrument, No. 1106, represents a slight evolution in the first pattern barometer – the barometer retailed by Dixey shown elsewhere on this site is exactly as per the image in the N&Z treatise.
By 1861, Negretti & Zambra had succeeded in producing the smaller watch-sized 1¾” dial instruments, effectively defining the majority of production of this first pattern instrument to a year or so, thus the scarcity.
In wonderful original condition, this pocket barometer is very much a collector’s piece.
Dimensions: 3¼” wide x 1¾” deep
Stock No: PB0400
Price: Not currently for sale
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