Watkin Patent pocket barometer having finely engraved and silvered 3” brass dial with tri-concentric altitude and barometric scales, reading indicator set at 6 o’clock, calibrations from 21-31 inches of mercury and from 0– 10,600ft (altitude), “Watkin Patent” in an arc above the centre with “Compensated” and serial “No 1012,” the lower dial signed by the maker “J. Hicks, 8, 9, &10 Hatton Gardens, London.” Fine blued-steel pointer, the bezel with very fine telltale spring anchored to arbour. Specialised 1½” capsule-driven movement constructed in lacquered brass and aluminium, arbour tensioned on a coil spring with helical drive, separate sub-chassis supporting fusee lever, scale indicator with roman numerals. The plain aluminium case with turned pillar and suspension ring, the rear having compensation adjustment port set at 4 o’clock as viewed.

Contained within its original brown pig skin over wood blue velvet lined case with snap closure on a button release.

Constructed almost entirely of aluminium, this instrument bears one of the highest recorded serial numbers. It is unlikely, judging from serial numbers, that more than around 1,500 of these instruments of all types were manufactured, and by far the greater number were of lacquered brass. Aluminium, the carbon fibre of the 19th century was extremely expensive and in short supply, thus items manufactured in this material were considerably more expensive than brass or steel. It is likely, due to its very light weight, that this instrument was intended for mountaineering at the lower altitudes.

Serviced, cleaned and calibrated, the aluminium case re-lacquered for conservation. The leather case in exceptional original condition, the lid velvet faded.

Working well with excellent sensitivity and smooth progression. A true collector’s piece.

Major (later Colonel) Henry Samuel Spiller Watkin of the Royal Artillery was granted a British patent no. 3425 for a rotary indicator and dial scale on 11 March 1886.