Hairspring Compass with Lengthening Bar and Pen Point
date: label: date made
content: early 20th century
notes: label: Description
content: This metal compass has a cylindrical scrolled handle. The upper parts of the legs have decorative grooves on either side. A thumbscrew on one leg may be used to finely adjust the angle of the leg (hence, the name "hairspring"). The lower parts of the legs are hinged and are attached by screws so that the pencil point and needle point may be replaced by the pen point or lengthening bar contained with the instrument. Small thumbscrews on the needle, pencil, and pen points allow for fine adjustments.
label: Description
content: The donor of this object, William J. Ellenberger (1908–2008), studied electrical and mechanical engineering at The George Washington University between 1925 and 1934. He then worked for the Potomac Electric Power Company and the National Bureau of Standards. During World War II, he served in the U.S. Army Signal Corps. He was a civilian construction management engineer for the army from 1954 to 1968, when he became a private consultant. He may have acquired this instrument during his studies or early career.
label: Location
content: Currently not on view
topic: label: Subject
content: Mathematics
label: Subject
content: Drawing Instruments
setName: label: See more items in
content: Medicine and Science: Mathematics
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content: Science & Mathematics
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content: Dividers and Compasses
creditLine: label: Credit Line
content: Gift of William J. Ellenberger
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: 1981.0933.20
label: accession number
content: 1981.0933
label: catalog number
content: 1981.0933.20
objectType: label: Object Name
content: compass
label: Object Name
content: compass, drawing
physicalDescription: label: Physical Description
content: metal (overall material)
label: Physical Description
content: steel (overall material)
label: Measurements
content: overall: 1.5 cm x 16 cm x 2.5 cm; 19/32 in x 6 5/16 in x 31/32 in