Vernier Compass with Telescope

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: 5 3/4 in; 14.605 cm; needle: 4 1/2 in; 11.43 cm; telescope: 8 3/4 in; 22.225 cm; vertical circle: 3 1/2 in; 8.89 cm; overall in case: 5 in x 10 3/8 in x 7 1/8 in; 12.7 cm x 26.3525 cm x 18.0975 cm
Museum: National Museum of American History
Credit line: Robert V. R. Reynolds

The inscription on this compass reads "W. & L. E. Gurley, Troy, N. Y." Gurley described this as a "Pocket Railroad Compass with Telescope." The form, with the folding sights offset so that the telescope is aligned with the north south line, was made between 1887 and 1920. 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. New, it cost $58.

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.

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

Vernier Compass with Telescope

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