Is your barometer of any value? I am not curious, of course, as to how many euros you might get if you were to put the trusted instrument beneath your coat and proceed in the direction of your local pawnshop. No, I pose the question of whether it can be relied upon to tell you about future weather. Should it indeed be that - a trusted instrument?
The barometer, in the strict sense, gives you a reading of the atmospheric pressure. In addition to numbers for "millibars" or "inches of mercury", the dial usually provides helpful advice, which ranges from dire warnings of "rain" and "storms" to cheery intimations of "bright" and "sunny" weather.
The needle moves backwards and forwards during a spell of unsettled but relatively "normal" conditions through a range roughly defined in "clock" terms by the region between "ten to" and "ten past"; "twenty past" suggests a heat-wave is upon us, and if it goes back in the vicinity of "twenty to" - watch out!
The effectiveness of the barometer as an indicator of future weather is limited. Accurate forecasts are difficult enough for a meteorologist with up-to-the-minute reports of temperature, pressure, humidity and wind over a large area of the globe.
The barometer, on the other hand, merely measures the atmospheric pressure at a single point, so it is asking a lot of the instrument to expect consistently accurate predictions based on this information alone.
But this said, the behaviour of the barometer does offer some clues as to the future. Perhaps the most important thing is that the pressure tendency - whether pressure is rising or falling - is usually more important than how high or low it is.
In a general way, high pressure is indeed associated with quiet, settled weather, and low values often bring changeable and windy conditions, but there are many exceptions to this rule.
You will get more guidance from the instrument if you also note the direction of movement of the needle, having used the static pointer to mark a previous reading some hours earlier.
Rising pressure usually means an improvement in the weather but, meteorologists say, "rapid rise, rapid fall" - a surge in pressure seldom lasts long and is soon followed by a sharp drop which heralds the approach of the next depression.
A slow, steady rise, on the other hand, often means that an anticyclone is becoming established over the area, which may result in a spell of calm and sun ny weather. In the case of falling pressure, however, the faster it drops, the worse the likely consequences.