Alluard Hygrometer
date: label: date made
content: early 20th century
name: label: maker
content: Gaertner Scientific Corporation
notes: label: Description
content: Emile Alluard, professor of physics at the University of Clermont-Ferrand and director of the meteorological observatory on the nearby Puy-de-Dôme, described this type of hygrometer in 1878. A modification of Regnault's instrument, it consists of a square vessel made of polished nickel-plated brass; at either side of the vessel, but not touching it, are strips of similar material. In use, the vessel would be filled with ether, and this ether would be cooled by evaporation by means of an aspirating bulb. When dew appears on the shiny surface of the vessel, a thermometer in the vessel indicates the temperature of the ether at that point. A second thermometer (lacking in this example) measures the ambient temperature.
label: Description
content: Robert A. Millikan described the Alluard hygrometer as being one of the "most perfect forms of the dew-point hygrometer" in his <i>Mechanics, Molecular Physics and Heat,</i> a popular college text that was first published in 1903, and that aimed "to present Physics as a science of exact measurement." The illustration on p. 167 shows an Alluard hygrometer made by William Gaertner, a German immigrant who settled in Chicago and who specialized in precision instruments.
label: Description
content: This example is marked "WM. GAERTNER & CO. CHICAGO." It was made between 1898 and 1923, when the firm traded as Wm. Gaertner & Co.
label: Description
content: Ref: M. Alluard, "Nouvel Hygromètre a Condensation,"<i> Journal de Physique et le Radium</i> 7 (1878): 328-330.
label: Location
content: Currently not on view
place: label: place made
content: United States: Illinois, Chicago
setName: label: See more items in
content: Medicine and Science: Physical Sciences
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content: Thermometers and Hygrometers
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content: Measuring & Mapping
creditLine: label: Credit Line
content: Kalamazoo College
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: PH.323821
label: catalog number
content: 323821
label: accession number
content: 256846
objectType: label: Object Name
content: Alluard hygrometer
physicalDescription: label: Measurements
content: overall: 31 cm x 13 cm; 12 7/32 in x 5 1/8 in
label: Measurements
content: overall: 11 1/8 in x 4 1/2 in; 28.2575 cm x 11.43 cm