Hairspring Compass with Lengthening Bar and Pen Point

Object Details

Description: 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.; 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.
Location: Currently not on view

early 20th century

Physical Description: metal (overall material); steel (overall material)
Measurements: overall: 1.5 cm x 16 cm x 2.5 cm; 19/32 in x 6 5/16 in x 31/32 in

See more items in: Medicine and Science: Mathematics; Science & Mathematics; Dividers and Compasses

National Museum of American History

GUID (Link to Original Record): https://n2t.net/ark:/65665/ng49ca746a7-2f97-704b-e053-15f76fa0b4fa