Gurley Surveyor's Vernier Compass

Description
This compass is marked "W. & L. E. Gurley Troy, N.Y." Since the signature--with its v-shaped trenches and lines of varying weight--was clearly engraved by hand, the compass was made between 1852 when the Gurleys started out in business, and before the middle of 1876, when their new engraving machine was up and running.
The variation arc on the south arm extends 20 degrees either way; the vernier is moved by a tangent screw, also on the south arm, and reads to 2 minutes. Two level vials are on the north arm. The side of one vertical sight is graduated to half degrees for determining angles of elevation or depression. In 1871, a compass of this size and design cost $50.
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
Object Name
compass
maker
W. & L. E. Gurley
Measurements
overall length: 15 1/2 in; 39.37 cm
needle: 6 in; 15.24 cm
place made
United States: New York, Troy
ID Number
PH*328411
catalog number
328411
accession number
272530
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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