James Green Hygrometer

Henri Victor Regnault, professor of physics at the College de France in Paris, described this type of instrument in 1845. It consists of a brass stand; a silver tube into which ether is poured and through which air can be made to pass; a thermometer to take the temperature of the ether; and another to measure the ambient air.
This example has two mercury-in-glass thermometers, each of which has a milk-white back marked "Jas. Green. 175 Grand St. New York." The clear front of one is graduated every ½ degree Fahrenheit from -15 to +130. The clear front of the other is graduated every degree Fahrenheit from -10 to +120. It was made between 1849 and 1875 when James Green was working at this address in New York City. It came to the Smithsonian from the U.S. Military Academy.
Ref: H. V. Regnault, "Études sur l'hygrométrie," Annales de Chimie et de Physique 15 (1845): 129-236, on 196-201.
Negretti & Zambra, Treatise on Meteorological Instruments (London, 1864), pp. 104-105.
Currently not on view
Object Name
Regnault hygrometer
date made
James Green
place made
United States: New York
ID Number
accession number
catalog number
Measuring & Mapping
Thermometers and Hygrometers
See more items in
Medicine and Science: Physical Sciences
Thermometers and Hygrometers
Data Source
National Museum of American History, Kenneth E. Behring Center
Credit Line
U.S. Military Academy

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