Surveyor's Vernier Compass

Its magnetic needle pointed north, and sights or a small telescope let a surveyor measure directions and boundaries.

Maker: W. & L. E. Gurley
Place: United States: New York, Troy
Dimensions: overall: 4 3/8 in; 11.1125 cm; needle: 3 1/2 in; 8.89 cm; overall: 6 in x 4 3/4 in x 4 7/8 in; 15.24 cm x 12.065 cm x 12.3825 cm
Museum: National Museum of American History
Credit line: U.S. Geological Survey

Gurley described this as "a most excellent and portable little instrument," noting that it "is especially useful for the surveyor of government lands." New, it cost $21. 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. The U.S. Geological Survey, was established in 1879, and transferred this example it to the Smithsonian in 1907.

Ref: W. & L. E. Gurley, A Manual of the Principal Instruments Used in American Engineering and Surveying (Troy, N.Y., 1878), p. 138.

The museum's own record (Smithsonian, National Museum of American History)

Surveyor's Vernier Compass

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