Woodruff's Mercury Barometer

Lum Woodruff, a resident of Ann Arbor, Michigan, who reported weather observations to the Smithsonian Institution, patented a portable barometer that proved to be extremely popular. Its key feature was a divided cistern so constructed that, when the tube was full of mercury, the lower portion of the cistern would be as well, and it could be shut off from the now empty upper portion.
Charles Wilder converted an old factory in Peterborough, New Hampshire, into a barometer shop in the fall of 1861, and began touting the virtues of Woodruff’s instrument. It was, he said, “simple, durable, accurate, perfectly portable, and very cheap,” and also “a very beautiful and ornamental piece of furniture.” It promised farmers a five percent savings on all their crops. For scientific men it offered “superior accuracy.” And for “gentlemen of leisure and cultivation” it offered a “never ending and constantly varying study of interest.”
This example was owned by John King, a Cincinnati physician who was interested in meteorology. It seems to be a "No. 1, Ornamental" style instrument that sold, originally, for $15. The silvered face at the top is marked “CHARLES WILDER / PETERBORO / N.H.” and “WOODRUFF’S / PAT. / JUNE 6, 1860.” The barometer scale extends from 27 to 31 inches of mercury, and is graduated into tenths and read by vernier to hundredths. The mercury-in-glass thermometer, also at the tope, extends from 0 to 110 degrees Fahrenheit.
Ref.: Lum Woodworth, “Barometer,” U.S. Patent 25,626 (1860).
Wilder’s advertisements in American Agriculturist 21 (1862): 191, and in The Bankers’ Magazine 12 (June 1863): 40.
Currently not on view
date made
Wilder, Charles
place made
United States: New Hampshire, Peterborough
overall: 37 in x 4 5/8 in x 1 7/8 in; 93.98 cm x 11.7475 cm x 4.7625 cm
ID Number
accession number
catalog number
Credit Line
Mrs. Hallie Stephens Caine
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Medicine and Science: Physical Sciences
Measuring & Mapping
Data Source
National Museum of American History


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