An aneroid barometer is an instrument that measures atmospheric pressure without the use of liquid. It works by means of a sealed, partially evacuated metal capsule, which expands and contracts as air pressure changes, with its movement magnified through a system of levers and a chain to turn a pointer on a dial.
The aneroid was invented by the French scientist Lucien Vidie in the 1840s and quickly became popular because it was compact, robust and easily transported, unlike mercury barometers, which were fragile and difficult to move. By the later nineteenth century aneroid barometers were made in vast numbers in France, Britain and Germany, in forms ranging from pocket barometers and surveying instruments to wall-mounted barometers in carved oak cases and brass ship's barometers. Many were combined with thermometers, and the related barograph records pressure changes on a paper chart. Retailers often put their own names on the dial. Collectors look for clean silvered or enamel dials, original cases, makers' or retailers' signatures, and good working order. An aneroid barometer requires little maintenance, though it may need occasional adjustment, and a well-made example remains both a practical and decorative addition to a hall or library.
