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The inscription on the face of this circular metal hygrometer—“Made in Germany / D.R. P. No. 16568 / Hygrometer”—refers to the German patent issued to Otto Mithoff, an engineer in Berlin, in 1881. Other inscriptions read "Outdoor Fluctuations" and "Indoor Fluctuations" and there is a scale running from Full Saturation to Absolutely Dry. This English wording suggests that this example was designed for sale in England or the United States.
Ref: Otto Mithoff, “Hygroskop aus der Inneren Haut der Eierschlen hergestellt,” German Patent 16568 (March 18, 1881).
“Hygroskop von O. Mithoff in Berlin,” Dingler’s polytechnische Journal 245 (1882): 452.
Currently not on view
Object Name
date made
after 1881
place made
overall: 3 13/32 in; 8.636 cm
overall: 1 3/4 in x 3 3/8 in; 4.445 cm x 8.5725 cm
ID Number
accession number
catalog number
Credit Line
U.S. Military Academy
Science & Scientific Instruments
See more items in
Medicine and Science: Physical Sciences
Data Source
National Museum of American History
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