Daniell Hygrometer


John Frederic Daniell, a young English natural philosopher, described this form 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.

This example has a wood stand. The interior thermometer is mounted on a white porcelain plate that is graduated every degree C. from -9 to +50 and every two degrees F. from -24 +120. The exterior thermometer is mounted on a brass plate that is graduated every degree C. from -10 to +50 and every two degrees F. from +20 to +121. There is a gold band around the equator of the lower bulb.

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.

Location: Currently not on view

See more items in: Medicine and Science: Physical Sciences


Exhibition Location:

Credit Line: Gift of Trenton State University

Data Source: National Museum of American History

Id Number: 1982.0230.10Accession Number: 1982.0230Catalog Number: 1982.0230.10

Object Name: hygrometer

Measurements: overall: 12 in x 8 1/4 in x 5 in; 30.48 cm x 20.955 cm x 12.7 cm

Guid: http://n2t.net/ark:/65665/ng49ca746b2-5bbb-704b-e053-15f76fa0b4fa

Record Id: nmah_1289954

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