A TEST BAROMETER BY NEGRETTI & ZAMBRA, LONDON, CIRCA 1950 the mercury tube with aluminium case divided to 1000ft with adjustable scales and side mounted thermometer, bedplate with bubble level, threaded adjustable screw feet, cast iron cistern and rubber connecting tube, the maker's plate signed and numbered 'M/8875', 108cm high, the base 27.5cm in diameter

This type of barometer was for precision testing the calibration of aneroid barometers. They were supplied to the Air Ministry at an original cost of £54.