Daniell Hygrometer
date: label: date made
content: ca 1831-1844
name: label: maker
content: J. Newman
notes: label: Description
content: John Frederic Daniell, a young English natural philosopher, described this type of instrument in 1820. It consists of two glass balls, one partially filled with ether and the other covered with muslin, connected by a thin tube from which the air has been evacuated. There is a thermometer in the tube above the ball with the ether, and another on the supporting stand. When a few drops of ether are poured on the muslin, their evaporation chills the covered ball; that in turn causes the ether vapor inside the instrument to condense, thereby cooling the other ball and causing dew to form on its surface. These instruments, Daniell said, were "accurately constructed, and packed in a box for the pocket, by Mr. Newman, Lisle-Street." The reference was to John Frederick Newman, a noted instrument maker in London.
label: Description
content: The stand of this example is metal. The interior thermometer is mounted on a white ivory plate, the front is graduated every degree Fahrenheit from +15 to +95, and the back is marked "5 x 31 J. NEWMAN LONDON." The exterior thermometer is missing, and the dry bulb is broken. The U.S. Military Academy purchased it sometime between 1831 and 1844.
label: Description
content: Ref: J. F. Daniell, "On a New Hygrometer, which Measures the Force and Weight of Aqueous Vapour in the Atmosphere, and the Corresponding Degree of Evaporation," <i>Quarterly Journal of Science</i> 8 (1820): 298-336.
label: Location
content: Currently not on view
place: label: place made
content: United Kingdom: England, London
setName: label: See more items in
content: Medicine and Science: Physical Sciences
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content: Military
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content: Thermometers and Hygrometers
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content: Measuring & Mapping
creditLine: label: Credit Line
content: U.S. Military Academy
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: PH.315733
label: catalog number
content: 315733
label: accession number
content: 217544
objectType: label: Object Name
content: Daniell hygrometer
physicalDescription: label: Measurements
content: overall: 6 3/8 in x 4 1/8 in x 1 3/4 in; 16.1925 cm x 10.4775 cm x 4.445 cm