A commercial version of a combined barograph & thermograph by Negretti & Zambra. Set into a metal case with a glass panel at the front & 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’ & ‘Barograph’ & 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.