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Barometer

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probably made in England

Barometer
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The origins of the Dutch weather glass are obscure. The instrument was certainly being produced in the 17th century by the glass-blowers of Liege, and continues to be produced on both sides of the Atlantic for domestic use. They are almost impossible to date precisely.

This spouted container is kept indoors at a stable temperature and half filled with coloured water. The space above the liquid, is not, as in the mercury barometer, a vacuum, but contains air and water-vapour which expands and contracts with temperature. The level of water in the spout is therefore controlled by both temperature and pressure.

The back of this instrument is flat so that it can be hung against a wall. As late as 1897, a patent was taken out for an improvement, namely a graduation on the spout so that changes could be seen more clearly. These changes are more of a general indication than a precise scientific measure.

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