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Negretti & Zambra Isothermal Altimeter c.1955

Price $726.00 Sale

A very rare British military issue Negretti & Zambra precision Isothermal Altimeter, serial no.P/113135, made in England c.1955.

The altimeter has a 12cm (4.75in) diameter white enamelled dial calibrated in metres, with the markings 'Height,' 'Metres' and 'Isothermal (50°F) Metres, H=19075.5 Log (29.9/P),' a very finely made lightweight aluminium pointer, and a bevelled glass within a rotating bezel. The dial is signed 'Negretti & Zambra, London', and has the serial number P/113135. Set into the centre of the dial is a thermometer calibrated in degrees Fahrenheit with a range from 0-120°. The altimeter is housed in a very heavy nickel-plated brass drum type case, marked 'Service Part No W.10/WK.00152', on the base, above a large broad arrow government military service-issue mark. These markings suggest that it was originally issued to the British army, although the blue-grey colour scheme of the case looks like that often seen on RAF equipment. Negretti & Zambra specialized in aircraft and aviation instruments and manufactured a variety of instruments for the Ministry of Munitions in WW1 and the Air Ministry in WW2.

The altimeter comes complete with its original foam-lined. grey painted, aluminium transport case, with matching serial and service part numbers, broad arrow mark, and milled screw lid lock. The exterior of the case has metal loops for the webbing shoulder strap. There are three screw holes in the base, which may be a later modification. Inside the lid there is a Negretti & Zambra label, and a clip for a small adjustment screwdriver. On the exterior of the lid there is a 1993 dated calibration label. The case also has a separate circular metal plate with three screw holes and a foam centre. This may have been intended to fit inside the lid to provide extra protection for the altimeter whilst in transit.

Negretti & Zambra: Negretti & Zambra of London were highly successful scientific and optical Instrument makers throughout the Victorian and Edwardian eras. Henry Negretti (1818-1879) and Joseph Zambra (1822-1897) formed their partnership in 1850. The company produced scientific and optical instruments and also had a photographic studio based in London. They were appointed opticians and scientific instrument makers to Her Majesty Queen Victoria, Prince Albert, King Edward VII, the Royal Observatory and the British Admiralty. Henry Negretti was the first man to take aerial photographs of London from a balloon. Throughout World War One Negretti & Zambra produced instruments for the Ministry of Munitions and developed many instruments for the Air Ministry, including a mercury-in-steel distance thermometer for taking oil and air temperatures in aircraft which was patented in 1920. Their work with the Ministry of Munitions between 1914-18 saw significant innovation in the field of early aviation instruments. After WW1 much of the company’s output was concentrated on projects for the Air Ministry. During WW2 Negretti & Zambra made thermometers and boost gauges for the RAF's Spitfire, Hurricane and Lancaster aircraft. In 1950 Negretti & Zambra had 821 employees in Britain, and by 1961 the workforce had increased to over 1200, manufacturing industrial, scientific, meteorological and aeronautical instruments and aero-engine controls. By the 1980s the company's fortunes had declined and they finally ceased trading in 1985.


The altimeter is in very good condition, full working order, and passes the plastic bag test. The integral thermometer is in good working order. The dial, glass, bezel and pointer are all in very good condition. The nickel plated brass case is in very good condition with some marks. The aluminium transit case is in good condition, with general signs of wear and use and some marks. There is some wear to the painted finish of the base. The interior foam lining is in good condition, although the foam is quite old and inflexible. The webbing shoulder strap is in good condition.

Altimeter: 120mm (diameter),
Transit Case: 180mm (diameter) x 110 (height)
Weight: 3kg