Pocket barometer having silvered and finely engraved 1¾” spun dial calibrated in inches of mercury with a range from 23 to 31, the upper portion signed “L. Casella, Maker to the Admiralty & Ordnance, London,” the lower part marked “Compensated” and serial no. “2747.” Blued steel pointer set beneath a bevelled glass mounted in a rotating bezel with fine index. Barrel-form spun case with turned pillar and suspension ring. The verso with adjustment point at 4 o’clock. 1⅛” capsule-driven grained and lacquered brass movement raised on a stepped chassis with early “C” spring tensioning, bi-metallic compensation strip to primary lever.
The whole presented in its original circular burgundy moroccan leather over wood blue velvet and silk lined case, snap closure on a button release.
This instrument presented without an altimetric scale but with a very wide barometric pressure scale would be suited for use in the monsoon belt where pressures lower than 26″ of mercury may be encountered. Interestingly, the dial is lacquered – a feature that is unusual though noted on a few other instruments, the purpose here to protect the silvered surface of the dial from a salt-laden (sea) environment or high humidity, both of which may cause a darkening or unsightly degradation of the silvered finish. The instrument may, of course, also be employed as an altimeter, the index mounted on the rotating bezel setting a starting point of ascent or descent and a simple calculation made equating the change in pressure for a change in altitude.
Minor (bubble) flaw to glass, the case retaining much original gilt finish, some hazing and minor scratches, the dial with a grained effect caused by ageing of original applied lacquered finish, the leather case retaining most of its original high gloss glaze, the leather over the button intact, the material lining fresh and bright.
A very attractive and early instrument by one of the world’s leading makers, this pocket barometer has been checked, serviced and conserved and is in excellent working order. In very crisp original condition, it is certainly a collector’s piece.
Dimensions: 2½” diameter x 1″ deep
Stock No: PB0442