Dietzgen 1298-D Blackboard Protractor
date: label: date made
content: ca 1950
name: label: maker
content: Eugene Dietzgen Company
notes: label: Description
content: Blackboard dividers that are different from this instrument are advertised as model number 1781 in the Frederick Post Company's 1930 and 1936 catalogs. The instrument is not shown in the 1949–1950 catalog.In the 16th and 17th centuries, surveyors and navigators began to use instruments made especially for measuring off angles. These were generally small instruments made of metal and finely divided. In the years following the Civil War, as the number of American high schools grew, so did the number of students studying practical geometry and trigonometry. To teach them, teachers used inexpensive protractors made for use at the blackboard.
label: Description
content: This example is made of fiberboard, painted white on the front, and has a wooden handle so that it can be held upright. It is divided along the edge to intervals of 5 degrees. By comparison, most protractors are divided much more finely. The Eugene Dietzgen Co. of Chicago sold blackboard protractors like this one from about 1925.
label: Description
content: The instrument was used by Margaret G. Aldrich (1918-2007), who taught at Montgomery College from 1957 to 1984, chairing of the math department on the Takoma Park campus for many years. She had an undergraduate degree in mathematics and an M.A. in psychology, both from the University of Minnesota.
label: Location
content: Currently not on view
place: label: place made
content: United States: Illinois, Chicago
topic: label: Subject
content: Education
label: Subject
content: Mathematics
label: Subject
content: Women's History
setName: label: See more items in
content: Medicine and Science: Mathematics
label: See more items in
content: Women Teaching Math
label: See more items in
content: Science & Mathematics
label: See more items in
content: Protractors
creditLine: label: Credit Line
content: Gift of L. Thomas and Margaret G. Aldrich
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: 1999.0117.02
label: catalog number
content: 1999.0117.02
label: accession number
content: 1999.0117
objectType: label: Object Name
content: protractor
physicalDescription: label: Physical Description
content: wood (overall material)
label: Measurements
content: overall: 2.5 cm x 39.5 cm x 20 cm; in x 15 9/16 in x 7 7/8 in