Railroad Compass

Railroad Compass

<< >>
Usage conditions apply
Downloads
Description
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.
Location
Currently not on view
Object Name
Surveyor's Compass (Railroad)
date made
1868-1876
maker
W. & L. E. Gurley
place made
United States: New York, Troy
Measurements
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
PH.329729
catalog number
329729
accession number
278336
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
Nominate this object for photography.   

Our collection database is a work in progress. We may update this record based on further research and review. Learn more about our approach to sharing our collection online.

If you would like to know how you can use content on this page, see the Smithsonian's Terms of Use. If you need to request an image for publication or other use, please visit Rights and Reproductions.

Comments

East and West are reversed on almost all American surveyors compasses and transit instrument. This is because, when you sight from the south end of the instrument, the needle will point to the name of the direction in which you are looking. It's thus not a mistake.
The east and west appear improperly engraved ? Is that on purpose? Why do they appear switched?

Add a comment about this object