Dicas Hydrometer

Dicas Hydrometer

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John Dicas was an instrument maker in Liverpool who, in 1780, received British patent #1,259 for “constructing hydrometers with sliding-rules to ascertain spirit strength.” The new form was soon well known in the United States. To pay off the Revolutionary War debt and fund the new American government, the U.S. Congress established a tariff in 1790. The new law described six classes of spirits, ranging from 10% under proof to more than 40% above proof, where proof was understood to mean equal parts alcohol and water. Determination was to be made with a Dicas hydrometer. Similar regulations pertained to the various Congressionally mandated excise taxes.
An ivory tag on the in wooden box of this example is marked “DICAS’S / HYDROMETER / BY JOSH LONG / LITTLE TOWER STREET / LONDON.” The hydrometer is brass, and equipped with 36 brass weights that can screw onto the spindle on top. The ivory sliding rule is marked "J. LONG – LONDON.” The wood sliding rule is unsigned. The thermometer on ivory backing marked “DEBALLIO & ZOON / ROTTERDAM” is obviously a replacement. Joseph Long began in business at 20 Little Tower Street, London, in 1820, and was still there in the 1880s.
Currently not on view
Object Name
place made
United Kingdom: England, London
overall: 5.1 cm x 24.8 cm x 15.3 cm; 2 in x 9 3/4 in x 6 1/32 in
overall in case: 2 1/8 in x 9 7/8 in x 6 in; 5.3975 cm x 25.0825 cm x 15.24 cm
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Medicine and Science: Physical Sciences
Data Source
National Museum of American History
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