Daniell Hygrometer by Newman

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.
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.
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," Quarterly Journal of Science 8 (1820): 298-336.
Object Name
Daniell hygrometer
date made
ca 1831-1844
J. Newman
place made
United Kingdom: England, London
ID Number
catalog number
accession number
See more items in
Medicine and Science: Physical Sciences
Measuring & Mapping
Thermometers and Hygrometers
Data Source
National Museum of American History, Kenneth E. Behring Center
Credit Line
U.S. Military Academy

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