WWI Air Altimeter as Barometer by Short & Mason C1920

A very scarce aluminium Short & Mason Mk V aircraft altimeter repurposed as an aneroid barometer retailed by Jw Ray Liverpool c1920 Aneroid barometer having 3½” silvered and engraved dial, the barometric scale in inches of mercury with a range from 26” - 31”, divided to 1/10ths”, the upper part marked “Compensated for Temperature,” the lower carrying the retailer’s details, “J.W. Ray & Co, Liverpool.” The outer silvered index ring driven by bezel mounted knurled brass knob, having basic weather prognostications in red for falling pressure and black for rising pressure. Japanned aluminium pointer with counterweight under bevelled glass, retained within an aluminium bezel with knurled setting wheel. 1¼” single capsule driven conventional first quality barometer-type movement. All contained within a cast black-painted aluminium case with compensation port to verso, designed for panel mounting. Condition: The subject of a full service, conservation, and calibration under laboratory conditions. The movement working well showing a maximum error across the scale of less than 0.03” across the normal range of use, highly sensitive with good progression. See performance chart. A very good example in well above average condition, the dial essentially clean, some slight ageing, the glass with light marks. The pointer repainted. Comments: A very unusual piece, this aneroid barometer was constructed from used aircraft altimeter parts after World War I, not only indicated in the use of aluminium, but indeed the reverse of the dial is marked “Height” and “Non-Luminous”, as well as the maker’s name “Short & Mason Ltd.” and the index ring has the engraving for an altitude scale 0-17,000ft to its verso - the wear to the reverse of the dial and the application of a scale strongly suggest that this instrument had seen use in an aircraft before being repurposed. Short & Mason were a major manufacture of aircraft altimeters in Wwi and this barometer is essentially a variation of their Mk V aircraft altimeter, used by the Royal Flying Corps, the Royal Naval Air Service, and subsequently the Royal Air Force, as shown in the image of a Wwi instrument - the two horizontal lines shown on the back of the dial correspond to the positioning of “Mark Vb” and the serial number. A scarce, very attractive and fully working instrument in better than average condition, a commentary on surplus Great War production, and ideally suited to the restoration of early C20th automobiles or simply for domestic use. Certainly collectable and really quite unusual.