ANEROID DESK BAROMETER Circa 1860 England
M&R167
ANEROID DESK BAROMETER
Circa 1860
England
The dial
The circular silvered brass dial has a scale at the top, divided into English inches (28 to 31) with the corresponding weather conditions. Under the scale is the text Holosteric Barometer, which is another term for aneroid barometer. The atmospheric pressure is indicated by a blued steel pointer with an arrowhead and a crescent shape on the opposite side. There is also a turnable brass setting hand, so that it can be determined whether the air pressure has fallen or risen. A semicircular mercury thermometer is placed at the bottom of the dial, indicating the temperature in degrees Fahrenheit, with the text Fahrenheit’s Thermometer 34937. The dial is protected by glass set in an elegant bezel.
The case
The gilt brass case has a twist gilt brass decorative rim around the dial and a cut-out and engraved base at the bottom. There is a strut at the rear so that the barometer can be positioned at an angle.
Height: 22 cm., 20 cm, with the strut in position.
Width: 18.5 cm.
Depth: 5 cm, 11 cm, with the strut in position.
Literature
Bert Bolle, Barometers in beeld, Ch. 15.
Holosteric or aneroid barometer:
The first aneroid barometers came into production in 1847, based on a patent of inventor Vidi from 1844. They contained an almost vacuum, round flat drum with ribbed top and bottom. A steel spring ensures that the atmospheric air pressure does not compress the drum. Due to the air pressure fluctuations, the drum deforms slightly over a small distance. These minuscule movements are first amplified via a lever system, after which they are transferred to a rotating pointer. This system had the following advantages over the hitherto usual mercury barometer: low vulnerability, easy handling, insensitivity to movements at sea, small size and an easily readable scale