Edson's Hygrodeik

William Edson, a civil engineer in Boston, designed a "Hygrometrical Index" that, when connected to a common wet and dry bulb hydrometer, "will enable any one, by simple inspection of the instrument, to ascertain the relative humidity and dew-point of the air, also the absolute amount of moisture in the air, without the aid of tables or calculation." In this example, which came from Cornell College, the paper chart is marked "EDSON'S HYGRODEIK MANUFACTURED BY N.M. LOWE, BOSTON." Nathaniel M. Lowe is known to have manufactured Edson's Hygrodeik from 1866 until the early 1890s.
Ref: William Edson, "Hydrometer," U.S. Patent 48620 (1865), as well as similar patents in England and France.
William Edson, The Use of Edson's Hygrodeik (1865).
Currently not on view
Object Name
date made
ca 1866-1895
Lowe, Nathaniel M.
overall: 13 in x 8 1/2 in x 3 1/8 in; 33.02 cm x 21.59 cm x 7.9375 cm
part: 3/4 in x 8 1/2 in x 3 1/4 in; 1.905 cm x 21.59 cm x 8.255 cm
place made
United States: Massachusetts, Boston
ID Number
catalog number
accession number
See more items in
Medicine and Science: Physical Sciences
Measuring & Mapping
Thermometers and Hygrometers
Data Source
National Museum of American History, Kenneth E. Behring Center


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