Smithsonian - National Museum of American History, Behring Center

 
Physical Sciences Collection - Surveying and Geodesy

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Surveyor's Vernier Compass - click to enlarge

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Surveyor's Vernier Compass

Catalogue number:
PH*312755

Inscriptions:
"W. & L. E. Gurley, Troy, N. Y."

Dimensions:
5.75 inches diameter; needle 4.5 inches long; telescope 8.75 inches long; vertical circle 3.5 inches diameter

Discussion:
Gurley described this as a "Pocket Railroad Compass with Telescope." This form, with the folding sights offset so that the telescope is aligned with the north-south line, was made between 1887 and 1920. New, it cost $58. The rim is graduated to 30 minutes, and numbered in quadrants from north and south. The outside of the box has a variation arc that extends ± 35 degrees, and that reads by folded vernier to 5 minutes.

Ref: W. & L. E. Gurley, A Manual of the Principal Instruments Used in American Engineering and Surveying (Troy, N.Y., 1904), p. 140.

William H. Skerritt, Catalog of the Charles E. Smart Collection of Antique Surveying Instruments (Troy, N.Y., 1996), pp. 36-39.

Further Information:

Gurley
Surveyor's Compass

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