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It’s signed ‘NEGRETTI & ZAMBRA, LONDON’ on the faceplate with the inter-twined NZ logo and the patent no 6276/15.Weighing 500 grams, it stands just over 5.5” high, 3” wide, and there is a keyhole slot in the back making it suitable for hanging on a wall or standing on a desk/table/mantelpiece.Although unsigned, this is a fine example of a precision instrument and still practical for use today. The brass case has lost some of its laquer over the year, but is in sound condition with no dings or dents and a chip free bevelled crystal.This is a nice example of an antique brass pocket holosteric barometer engraved PHNB and made in the last quarter of the 19th century by the renowned French firm of Pertuis Hulot et Naudet Barometres for the English market. In full working order (it also passes the plastic bag pressure test) and measuring approximately 70mm in diameter by 28mm deep, it weighs just over 200 grams without its case.This is a late 19th century pocket barometer and altimeter, carrying the name of Negretti & Zambra on the dial.Unlike the majority of pocket barometers which have an adjustment screw through an aperture on the back of the case, this particular example adjusts the needle by rotating a knurled ring on the base which is first unlocked by loosening a small screw on the rim.This is a brass cased Mark IIB aneroid barometer signed 'A. The scale of pressure on the metal dial is expressed in millibars which was adopted by the Met Office in 1914 for their daily weather reports along with the inches scale until 1935, when the Mark 2 version was introduced which then omitted the scale of pressure in inches.
In full working order, this is an exceptional instrument by one of the most renowned makers of the 19th century.
Dating to after 1870, the barometric scale reads from 15 to 31 inches with an altimeter scale from zero to 20000 feet, which indicates it was constructed for use at high altitudes probably by hot air Balloonists or Mountaineers.
Housed in a brass case which is in very good condition, the clean frosted dial reads ‘NEGRETTI & ZAMBRA, LONDON, 13218' ’ and is housed under a clear bevelled crystal which in turn is held within the rotating bezel containing the altimeter scale.
Collectors of Negretti & Zambra instruments will recognise the extreme rarity of this box model version of the famous weather forecaster.
Dating to circa 1915/20 when the ‘weather forecaster’ system was patented, a number of variations were produced and this particular model was made in much smaller numbers than the circular brass or celluloid examples, hence its comparative rarity.