The aneroid barometer was invented by a Frenchman, Lucien Vidie, in 1843. He produced a metallic barometer which he called an aneroid, from the Greek, meaning “without liquid”. The principle of the aneroid barometer is the change in height of a sealed metallic chamber which has flexible upper and lower surfaces. As the pressure changes, so the height of the chamber varies which, in turn, moves an index pointer. As there was no need for a long tube of mercury, it was possible to build a compact instrument.
Aneroid barometers are less susceptible to shock and the transport problems associated with mercury instruments. All movements are tested and calibrated to sea level. Instructions are included so the instrument can be adjusted for height variations above sea level, as forecasts quote the sea level pressure, shown in isobars on a meteorological chart.