Gurley Surveyor's Vernier Compass

Description
The rim of this compass is graduated to 30 minutes. The variation arc on the south arm extends 20 degrees either way, and is read by folded vernier to 2 seconds. There is an outkeeper on the south arm, and two level vials on the north. The hand-engraved signature indicates a date of manufacture between 1852 and 1876. New, it cost $50.
The compass is equipped with a telescope that attaches to one of the sight vanes, and that is marked "W. & L. E. GURLEY, TROY, N.Y. PATENTED JULY 9, 1878." The reference is to patent #205,712 describing an Improvement in Telescope Attachments for Surveyors’ Compasses, and granted to William Gurley and Lewis E. Gurley.
Ref: W. & L. E. Gurley, A Manual of the Principal Instruments Used in American Engineering and Surveying (Troy, N.Y., 1871), pp. 23-27.
W. Skerritt, "W. & L. E. Gurley's Engraving Machine," Rittenhouse 11 (1997): 97-100.
Location
Currently not on view
maker
W. & L. E. Gurley
place made
United States: New York, Troy
Measurements
overall length: 15 1/2 in; 39.37 cm
needle: 6 in; 15.24 cm
overall in case: 4 5/8 in x 16 1/2 in x 8 3/8 in; 11.7475 cm x 41.91 cm x 21.2725 cm
ID Number
PH.335210
catalog number
335210
accession number
317998
Credit Line
Columbia University
See more items in
Medicine and Science: Physical Sciences
Measuring & Mapping
Surveying and Geodesy
Data Source
National Museum of American History, Kenneth E. Behring Center

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