A commercial version of a combined barograph and thermograph by Negretti and Zambra. Set into a metal case with a glass panel at the front and circular grill to the side (allowing air to circulate around the bi-metallic temperature coil). This instrument from the 1950’s is in working condition & the barograph movement comprises of the diaphragms with the separate section at the base which proved to be more accurate in tests – see extract from Negretti’s 1950 catalogue. The movement also has the pen arms engraved with ‘Thermograph’ and ‘Barograph’ and each linked to a gate suspension. The pen arms move freely past each other using ‘birds mouth’ pen nibs. A nice working instrument. Good condition for year.
Barograph & Thermograph Combined Instrument by Negretti & Zambra c. 1955 England