Pocket barometer having 1¾” silvered and engraved dial with barometric scale calibrated in inches from 25–31, the upper outer part marked with standard meteorological terms “Stormy, Rain, Change, Fair, Very Dry” and “Whiteside Cook’s Sea Level Aneroid, Patent No 14424,” the lower portion signed by the maker “Negretti & Zambra, London,” with serial no. “148” and the descriptor “Compensated.” Blued steel pointer, bevelled glass set in a rotating bezel with fine index. 1″ capsule driven movement with coil spring tensioning raised over a decorated chassis.
All contained within a gold barrel form case, the circumference with altitude scale from sea level to 6000ft, stations at 500ft intervals and divided to 100ths of a foot. Pocket watch pattern case extension with movement locking crown, suspension ring, calibration port to verso.
The verso bearing the inscription “Presented to Dr W.A. Carline as a slight momento of his great and valuable services as Honorary Treasurer of the Nottingham Meeting of the British Medical Association, 1892.”
All contained in its correct leather over timber, green velvet and silk lined case, snap closure on a button release.
Gold cased pocket barometers are considered very hard to find – coupled with the Whiteside Cook’s Patent makes this instrument rare indeed.
The instrument is essentially a standard pattern with the addition of an important innovation, Whiteside Cook’s Patent, a system that allowed readings to be read as if at sea level at any elevation up to 6000ft. The movement tensioned with the early coil spring pattern is interesting since the C-spring had been widely adopted – however, the C-spring was more easily fitted to larger instruments as it required a certain amount of vertical case space. Negretti & Zambra reverted to the coil spring in a bid to reduce the overall depth of the instrument. Later production saw the development of lower profile C-springs which then became universal to all instruments of this type.
In operation, the crown is turned anti-clockwise enabling the case verso to which the movement is attached to rotate. A scale from 0–6000ft is marked around the circumference of the case and the altitude is set by the engraved index point situated on the verso. The crown is then turned clockwise and the new value set and locked.
In the history of the of the aneroid barometer, this is one of the most important and useful innovations. It was used widely by this maker, notably in the Forecasting Aneroid, and it was copied extensively by Short & Mason (Tycos) and others.
Some slight shadowing to the dial, minor marks to centre, the case with light abrasions, very slight depression to verso. The leather case structurally sound, the leather in good order, slight wear and minor losses. The fabric interior bright and vibrant, the velvet slightly faded to upper case edge. Fully serviced and conserved, tested to full scale deflection, excellent progression and sensitivity. Minimal hysterisis.
Presented in a gold case, and with a very significant and scarce innovation, most definitely a collector’s piece.
Dimensions: 2¼” diameter x 1″ deep
Stock No: PB0961