Gurley Railroad Compass

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Description
W. & L. E. Gurley introduced this type of instrument--a railroad compass with one vernier on the limb--in 1868. This example has a hand-engraved signature, and so was made before the middle of 1876, when Gurley’s engraving machine was up and running. The upper plate carries the sights, two level vials, and the compass. The lower plate, wider than the upper, carries the circle, which is graduated to 30 minutes and read by vernier to single minutes. A tangent screw on the south arm moves the two plates relative to one another. A variation arc on the compass face extends 30 degrees either way. The folded vernier is moved by a rack and pinion located on the north arm, and reads to 2 minutes. The compass has a blackened or bronzed finish, and a silver–plated face. New, it cost $65.
The "Fagg & Bowe 1870" signature scratched on the inside of this compass refers to George S. Fagg and Archibald H. Bowe, who began working for Gurley in 1866. The "Edward Meister Baltimore 1872" signature refers to an independent instrument maker in Baltimore, Md. The "Geo. Shilling 1904 Wash. D.C." signature refers to an independent instrument maker in Washington, D.C. The "J. Heim 1885" signature has not been identified.
Ref: W. & L. E. Gurley, A Manual of the Principal Instruments Used in American Engineering and Surveying (Troy, N. Y., 1868), pp. 52–56.
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: 5 in; 12.7 cm
overall: 11 in x 14 7/16 in x 8 1/4 in; 27.94 cm x 36.67125 cm x 20.955 cm
ID Number
PH.330532
catalog number
330532
accession number
293490
Credit Line
Virginia Polytechnic Institute
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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