Pocket Barometer Altimeter in Case c.1939

A good lacquered brass aneroid pocket barometer altimeter in case by Francis Barker c.1939. Pocket barometer having 1¾" silvered and die struck dial, the outer crown-operated altitude ring calibrated in feet with a range from 0 – 8,000ft and divided down to 100ft, the inner barometric scale calibrated in inches of mercury with a range from 23" – 31" and divided down to 1/20th. Blued steel pointer and bevelled glass. Standard configuration temperature-compensated movement, dated "4/39," driven from a single 1" cell tensioned on a C spring, all contained within a semi barrel form brass case with ribbed embellishment, pendant, crown and suspension ring. Calibration port to verso. Presented in its correct brown leather over timber, green 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 from dynamic test. The movement working exceptionally well, accurate to better than 1/10th" Hg across the scale. The dial clear and clean, the leather case structurally sound with good external shine, the underside with wear. The fabric interior with some fading though intact. Comments: Although unsigned, this is almost certainly the work for Francis Barker, a major manufacturer of aneroid barometers at the time who produced almost solely for the trade, rarely self-signing instruments. A standard instrument but in quite above average condition, particularly pleasing in terms of accuracy and response. A collector’s piece.