A fascinating, wall mounted barometer using dyed water as the indicator that
looks good in your home.
This
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.
Included is a syringe for filling and red, green and yellow dye tablets that
may be mixed to produce the required colour. The hook shown is not
included.
How does it work?
Dimensions: (approx.)
25cm (10") high x 10cm (3") wide
These modern replicas are individually hand made, so each one is unique and makes an attractive wall
feature.
Model: GLB2
Price: £20.00
(£23.95 inc. carriage & packing*)
SORRY,
SOLD OUT
*
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 about one-third half filled with the dyed
water, so that the opening between the bottle and the spout is well covered. 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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