The Scientific and Attractive Wall DecorationThe barometers we sell are of the ANEROID type which means the method does not involve liquid. That is to say the movement of the needle is controlled by the expansion and contraction of small metal bellows within the works, which are in turn connected via a hairspring to a metal spindle attached to which is a small chain. It is this chain, which causes the needle to move in reaction to the bellows.
These bellows react to barometric pressure changes i.e. changes in the weather fronts and thus give an indication of a rise or fall, usually about 24 hours ahead.
The words on the Barometer face must be taken as general indications only, the main indicator being pressure related needle movement.
Setting Your BarometerThe needle is adjusted by means of a small screw usually located at the back of the movement. It should be moved very gently, and only small movements at a time.
To set up your barometer you can use either a known source e.g. an already-set, similar instrument or else you will need to obtain a reading from a local weather centre or the Met Office. The Met Office website will inform you of your local air pressure if you search your location (http://www.metoffice.gov.uk/weather/uk/se/se_latest_pressure.html). Setting this correctly is most important since the reading varies depending on how far above sea level you actually live.
The reading given will be based on the Noon forecast and will either be in Millibars e.g. 1020,1012.1016 etc. or in Barometric inches, e.g. 29.88, 29.65, 30.00 etc., the latter being the easiest to read on the Barometer face.