hair hygrometer
Dateafter 1885
Inventory Number1998-1-0817
ClassificationHygrometer
Subject
User
Blue Hill Meteorological Observatory
1885-present
Maker
Hottinger & Cie
1872 - 1880s
Cultural Region
Place of Use
Dimensionshygrometer: 27.6 × 15.4 × 7.5 cm (10 7/8 × 6 1/16 × 2 15/16 in.)
case: 8.7 × 29.4 × 17.5 cm (3 7/16 × 11 9/16 × 6 7/8 in.)
case: 8.7 × 29.4 × 17.5 cm (3 7/16 × 11 9/16 × 6 7/8 in.)
Material
Accessoriesa fabric or oilcloth covered wooden and felt box closed with two hooks
DescriptionAn iron rectangular frame resting on an iron base housing a thin brass bell shaped structure. A hair stretches from the top to the bottom of the structure at its center. The hair is coiled at the bottom and tension is supplied by a weight. At the bottom the hair connects to a pointer which points to an arched scale marked from 0 to 100%. The frame can be closed at the back by a sliding panel, and at the front by a piece of glass. About 2/3 of the way up the frame, two metal loops are attached on either side of the frame. Two hooks are attached, one on each side of the top of the frame.
From the discription of a similar instrument in the collection (1998-1-0818), it looks as if a piece of open weave cloth that would attach to the back of the frame is missing.
The iron casing is rusted.
From the discription of a similar instrument in the collection (1998-1-0818), it looks as if a piece of open weave cloth that would attach to the back of the frame is missing.
The iron casing is rusted.
Signedunsigned
Inscribedwritten in pencil on the base: 1
FunctionUsed to measure air humidity. A single hair (probably human) extends from the top to the bottom of the frame. The hair's length increases slightly in response to humidity. This hair is attached to a pointer with a scale in percentages, and any changes to its length move the pointer.
During its actual use in measurement, the front glass panel and the metal backing would be removed, exposing the hair to the ambient air.
An important feature of the hair hygrometer is its calibration mechanism. Before it is put to use, one would first wet the cloth (now missing) and slide it into the frame. Then one would close the hydrometer by restoring the metal backing and the front glass panel. The enclosed wet cloth would make the humidity rise to 100%. After wating for the humidity to rise, one would adjust the needle to 100% by turning the screw to which the hair is attached on top.
During its actual use in measurement, the front glass panel and the metal backing would be removed, exposing the hair to the ambient air.
An important feature of the hair hygrometer is its calibration mechanism. Before it is put to use, one would first wet the cloth (now missing) and slide it into the frame. Then one would close the hydrometer by restoring the metal backing and the front glass panel. The enclosed wet cloth would make the humidity rise to 100%. After wating for the humidity to rise, one would adjust the needle to 100% by turning the screw to which the hair is attached on top.
Historical Attributesnote in case: This or similar instrument used in making relative humidity obs. at Blue Hill in early days
Hottinger & Cie
Date: after 1885
Accessories: a fabric covered wooden and felt box closed with two hooks;
german language instruction sheet (copy in file);
Object number: 1998-1-0818
Department of Chemistry, Harvard University
Date: circa 1952
Accessories: a hinged wooden case with hook closures, and a paper insert
Object number: 1998-1-0828
Date: early 20th Century
Accessories: a hinged wooden case with hook closures, and explanatory diagram
Object number: 1998-1-0834
Jones & Son
Date: 1806-1825
Accessories: hinged wooden instrument case, with interior velvet padding
Object number: 5601
Jacques Paul
Date: circa 1780
Accessories: silk-lined wooden case with hook closures
Object number: DW0832
French
Date: 1850-1890
Accessories: set includes: brass stand base; T-shaped tube; hollow tube with side neck; tube with ring stands; brass holder for two thermometers; one thermometer; glass tubes with brass bottoms (2); felt lined, fitted case
Object number: 3825
Blue Hill Meteorological Observatory
Date: ca. 1900-1930
Object number: 1998-1-0877
E. Ducretet & Cie
Date: 1870-1890
Accessories: stand (DW0186b)
Object number: DW0186a
French
Date: 1850-1890
Accessories: set includes: thermometers (2); brass stand base; silver vessels on a T tube (2); curved glass tube with cork; stand tube with side neck; stand tube with holder for curved glass tube; brass clamp for thermometers
Object number: 3824
Carl Zeiss Jena
Date: circa 1926
Accessories: wooden box with two hook-and-eye latches to fasten front opening; in instrument file: instruction book (photocopy); Geissler tube labeled "H2"; carboard tube containing German thermometer C in stainless steel holder that screws into instrument; glass bottle with cork stopper labeled "Monobromnaphthalin, Germany nD=1 658"; small round cardboard box labeled "For Pulfrich Refractometer" containing one tubulure
Object number: 1996-1-0229
See also/See also
