A gilt brass aneroid barometer and a brass weather forecasting calculator, Negretti and Zambra, London, early 20th century The barometer with 3.5 inch circular silvered register calibrated 28-31 divided into twentieths and inscribed FORECASTING ANEROID, COMPENSATED, NEGRETTI & ZAMBRA, LONDON, No. 9027 to centre, with blued steel pointer set behind bevel glass, the circumference of the case calibrated with altitude scale 0-3,000 feet with the rear cover rotating to calibrate the pointer for altitude error by referencing an arrow mark engraved to the rim against the scale, with post incorporating knurled nut for locking the rear cover positioned at twelve o’clock, diameter 10cm (4ins); the weather forecasting calculator formed as three discs, the outer calibrated in inches for the barometer reading to the top edge and for the wind direction to the lower edge, the middle ring annotated for STEADY, RISING and FALLING and for summer or winter for lining up with the wind direction scale, the centre with instructions for use, sector revealing appropriate weather forecast and inscribed NEGRETTI & ZAMBRA, LONDON, PATENT 6276, 1915, with hinged strut to rear and suspension post (ring lacking), diameter 12cm (4.75ins); both contained in two-part hinged velvet lined case inscribed in gilt A.T.L. to lid, (case distressed) 15cm (16ins) wide. Provenance: Formerly the property of Lawrence Lord Trevethin (1843-1936) who served as Lord Chief Justice of England 1921-22. His son, Geoffrey Lawrence, 3rd Baron Trevethin and 1st Baron Oaksey, was a principal judge at the Court sitting for trials at Nuremberg after World War II, including that of Hermann Goering. The firm of Negretti & Zambra are recorded in Banfield, BAROMETER MAKERS AND RETAILERS 1660-1900 as being established in 1850 when a partnership 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 forecasting calculator was patented by Negretti and Zambra in 1915 using observations of actual weather conditions over a ten year period and was said to be 80% accurate by the manufacturers.