Accession No

3999


Brief Description

Hair hygrometer, Swiss, 1820 (c)


Origin

Switzerland


Maker


Class

meteorology


Earliest Date

Jan. 1, 1820


Latest Date

None


Inscription Date


Material

metal (brass); cloth (velvet); wood


Dimensions

box length 343mm; breadth 122mm; height 32mm


Special Collection


Provenance

Purchased from Peter Delehar.


Inscription


Description Notes

De Saussure type hair hygrometer in fitted box.

Brass hair hygrometer for measuring atmospheric moisture invented by Horace-Bénédict de Saussure in 1783. In hinged, black velvet lined fitted wooden case.
Scale 0-100 by 1.

Condition: good; not complete: hair element missing.


References

Allison Ksiazkiewicz; 'Measuring Air Humidity'; Explore Whipple Collections online article; Whipple Museum of the History of Science; University of Cambridge: https://www.whipplemuseum.cam.ac.uk/explore-whipple-collections/meteorology/measuring-air-humidity


Events

Description
A hygrometer is an instrument designed to measure the humidity of the air.

The sensing element of this hygrometer is human hair, which changes its length with changing humidity, contracting in dry weather and expanding when the air is damp. The hair is put under slight tension and linked to a pointer moving round the dial.

Hygrometers of this type are named after the Swiss scientist Horace Bénédict de Saussure, who in about 1775 found by experiment that degreased human hair could respond reliably to changing humidity and despite their fragility, many examples of these portable hair hygrometers were made. With the passage of time, few remain intact.
26/03/2008
Created by: Dr. Anita McConnell on 26/03/2008


FM:45050

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