Interesting Danish silver Réaumur pocket thermometer Circa 1815

Silver open faced by Urban Jürgensen
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An interesting and rare early Danish silver Réaumur pocket watch, circa 1815. Thermometer made to the design of Frederick Houriet. Dial signed.
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Diameter: 64 mm
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Signed: Urban Jürgensen  Copenhagen
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This type of pocket thermometer was first made by FRÉDERIC HOURIET followed by URBAN JÜRGENSEN and ABRAHAM LOUIS BREGUET. It was described by Houriet in an advertising leaflet, unfortunately undated. The bimetallic thermometer device is extensively explained and illustrated by Urban Jürgensen in “Principes Généraux de l’Exacte Mesure du Temps par les Horloges”, Copenhagen, 1805. This watch is illustrated in The Jurgensen Dynasty by John Knudsen.