Dietzgen 1298-D Blackboard Protractor

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.
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. This example dates from around 1950 and was used at Montgomery College in Takoma Park, Maryland.
Currently not on view
Object Name
date made
ca 1950
Eugene Dietzgen Company
Physical Description
wood (overall material)
overall: 2.5 cm x 39.5 cm x 20 cm; in x 15 9/16 in x 7 7/8 in
place made
United States: Illinois, Chicago
ID Number
catalog number
accession number
Science & Mathematics
See more items in
Medicine and Science: Mathematics
Data Source
National Museum of American History, Kenneth E. Behring Center

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