A scarce lacquered and gilt brass bi-rotational aneroid pocket barometer altimeter by Short & Mason No D39735 retailed by E.G. Wood, London c1935

Pocket barometer having 2½” silvered and die struck dial, outer altitude scale calibrated in feet with a range from 0  – 5,000ft divided down to 20ft, inner barometric scale calibrated in inches of mercury with a range from 26” –  31” divided down to 1/20th”. The upper part marked “Compensated” with serial “No D.39735,” the lower with retailer’s details, “E.G. Wood, 2 Copthall Court, Throgmorton Street, London EC2.”  Fine blued steel pointer, bevelled glass, bezel driven index.

Standard configuration movement of 1st quality with high finish, struck with Short & Mason “S&M” logogram, driven from 1½” capsule tensioned on a C spring. Contained within a semi drum form brass case, extension post and suspension ring, calibration port to verso.

Presented in its original oxblood 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. The movement working exceptionally well across the range with maximum error of less than 1/ 10th”, see performance chart.

The dial essentially unmarked with little sign of ageing, the brass case retaining a very high proportion of original gilded and lacquered finish, some slight losses, minor marks and signs of wear. The suspension ring a replacement. The travel case structurally sound, the leather in good condition generally, some signs of wear and minor losses. The fabric interior bright, the lid silk slightly faded, the velvet rim re-dyed. The button release replaced along with leather covering.

Comments: These are some of the best English-made pocket barometers of this age, made at a time when Short & Mason were producing their very finest instruments. The double rotation instruments were designed with greater accuracy and resolution in mind, the essence being the much more open scale than mainstream barometer altimeters. The design provided that the pointer may traverse the dial almost 1¾ times – this required special attention given to links and pivots in the train, the arbor sprung with a particularly fine and perfectly poised hairspring.

In every respect this is a lovely instrument, expressing obvious quality in design and operation with very good aesthetic properties. Now extremely hard to find, especially in this condition. Most definitely a collectors piece.

Edward George Wood founded his eponymous company in 1854, when he left the partnership of Horne, Thornethwaite & Wood. Wood died in 1896, but the business, mainly known as a leading magic lantern and slide manufacturer, continued to trade until 1939. It was situated at 2 Copthall Court from 1932 onwards.