Protractor and Ruler Scale

According to the accession record, this "special protractor and scale" is attributed to the factory operated by William and Lewis Ephraim Gurley in Troy, N.Y. No examples of this protractor could be identified in Gurley catalogs, although the "special" may refer to a special order placed by the U.S. Geological Survey, which in 1907 declared this instrument "obsolete" and transferred it to the Smithsonian.
This semicircular steel protractor within a rectangular frame is exactly like ID number MA*247967, except that there is no second scale to replace the sliding scale screwed to the top of the protractor. The number 1 is marked on the bottom of each of these two screws. This instrument also retains the bottom half of its original mahogany case, which is lined with blue velvet and bears two brass hooks for latching the case. The protractor is disassembled from the straight edge on which it slides so that both pieces fit in the case.
Reference: Deborah J. Warner, "Browse by Maker: Gurley," National Museum of American History Physical Sciences Collection: Surveying and Geodesy,
Currently not on view
Object Name
date made
W. & L. E. Gurley
Gurley, Lewis E.
Gurley, William
Physical Description
mahagony (overall material)
steel plate (overall material)
copper (overall material)
overall: 2 cm x 23 cm x 30.5 cm; 25/32 in x 9 1/16 in x 12 in
place made
United States: New York, Troy
ID Number
accession number
catalog number
Science & Mathematics
See more items in
Medicine and Science: Mathematics
Data Source
National Museum of American History, Kenneth E. Behring Center
Credit Line
Transfer from U.S. Geological Survey
Additional Media

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