A fascinating, wall mounted
barometer using dyed water as the indicator that looks good in your home
or conservatory.
This graceful,
hand-blown glass barometer comes to us from the late 17th century.
Made originally, it is believed, by glass blowers in the town of Liège, Belgium, it has been known
variously as a "Liège barometer", as a "water
barometer" or as an "Old Dutch weather-glass". It is
also known as a Goethe barometer after the name of the inventor.
How does it work?
Dimensions: (approx.)
20cm (8") high x 7.5cm (3") wide
These modern replicas are individually hand made in lead crystal
ensuring that each one is unique and makes an attractive wall
feature. We supply each barometer complete
with a filling aid, red colouring agent and the brass hanging hook - you
just supply the water!
Model: GLB
Price: £20.00 (£23.50 inc. carriage & packing*)
*
Carriage paid to; England,
Wales, Scotland (incl. Highlands &
Islands), N.Ireland, Isle of Man & the Isles of Scilly. Please
enquire for
elsewhere.
How does it work?
The glass is half filled with water, so that it covers the
opening between the bottle and the spout. To maintain equilibrium,
the air trapped in the bottle must at all times be at the same pressure
as the external atmosphere. Under these circumstances the air
pressure per unit area acting on both liquid surfaces is the same.
So, when atmospheric pressure increases, for example as a "high" approaches, the liquid in the spout is forced
down. This reduces the air volume in the bottle, which raises the
pressure of the trapped air, re-establishing equilibrium. Similarly during a "low" pressure the liquid in the
spout rises. The name "Old Dutch weather-glass" is more
correct than barometer, because the air and water vapour trapped in the
glass are affected by temperature changes. So the liquid level in
the spout is affected by both pressure and
temperature, rather than just
by pressure alone.
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