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*247917

Inscriptions:
"W. & L. E. Gurley, Troy, N. Y." and "U. S. G. S. No. 6"

Dimensions:
4.375 inches diameter; needle 3.5 inches

Discussion:

Gurley described this as "a most excellent and portable little instrument in locations," noting that it "is especially useful for the surveyor of government lands." New, it cost $21. This example belonged to the United States Geological Survey, which was established in 1879, and which transferred it to the Smithsonian in 1907. The rim is graduated to 30 minutes. The right side of the face is graduated to degrees, and numbered every 10 degrees from west to north, and from west to south. The outside of the box has a variation arc that extends ± 20 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., 1878), p. 138.

Further Information:

Surveyor's Compass
Gurley

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