Gurley Railroad Compass

This instrument marked "W. & L. E. Gurley, Troy, N.Y." was made between 1868 when the Gurleys introduced a railroad compass with one vernier scale on the limb, and the middle of 1876 when the firm's engraving machine was up and running. New, it cost $70. It belonged to Bowdoin College. 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. There is a variation arc on the compass face that 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. It has a blackened or bronzed finish, and a silver–plated face.
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.
Currently not on view
date made
W. & L. E. Gurley
place made
United States: New York, Troy
overall length: 15 5/8 in; 39.6875 cm
needle: 5 1/2 in; 13.97 cm
overall in case: 5 7/16 in x 16 5/8 in x 9 3/8 in; 13.81125 cm x 42.2275 cm x 23.8125 cm
ID Number
catalog number
accession number
Credit Line
Bowdoin College, Department of Physics
See more items in
Medicine and Science: Physical Sciences
Measuring & Mapping
Surveying and Geodesy
Data Source
National Museum of American History