In the late 1880s, a German meteorologist named Adolph Richard Assmann designed an aspiration instrument with a fan to draw air past the wet- and dry-bulb thermometers of a common psychrometer. Assmann also enclosed the device in double-walled ducts of polished metal designed to minimize the effect of radiation. This form remained in widespread use for many years.
The clockwork housing of this example is marked "R. Fuess / Berlin-Steglitz / No. 189500." The back side of the thermometer scales are marked "CENTIGRADE R. FUESS, BERLIN-STEGLITZ JENAER Normaliglas 16111."
Ref: R. Fuess, Liste D2 über Thermometer, Psychrometer, Hygrometer und Hypsometer (Steglitz bei Berlin, 1910), p. 6.
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