A SCARCE MET OFFICE PRECISION ANEROID BAROMETER MK. 2NEGRETTI AND ZAMBRA, LONDON, 1981The asymmetric silver-green painted cast alloy case with circular cover for the aneroid mechanism applied with label PRECISION ANEROID, BAROMETER MK. 2, REF. No. MET 20,005 RANGE 900-1050mb, M.O., SER. No. 1412/81 beside canted section with small glazed viewing aperture for the electric level indicator tube set beside on/off button over digital mb micrometer indication manually adjted via a plastic knob to the left hand side and with label READ ON BREAK, INCREASE PRESSURE READING, DECREASE PRESSURE READING, the left hand side also with D-cell batterypartment, the instrument secured via three turnscrews into original wooden case applied with repeat title label to front and leather strap to lid.The box 18cm (7ins) high, 23.5cm (9.25ins) wide, 15cm (6ins) deepProvenance: The exhibition collection of Barometer World Meum, Merton, Devon; acquired direct from the Meteorological Office.The firm of Negretti & Zambra are recorded in Banfield, Edwin BAROMETER MAKERS AND RETAILERS 1660-1900 as being established in 1850 when a partner between Enrico Negretti and Joseph Warren Zambra was formed. The firm became one of the most prolific makers of scientific instruments and continued trading well into the 20th century.The current instrument utilises a very light counter-balanced electrical contact arm mounted in jewelled bearings. Electrical contact is established by manually rotating the adjtment knob for the micrometer until a change in the stat of the electrical indicator tube can be seen.