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

Surveyor's Vernier Compass - click to enlarge

Surveyor's Vernier Compass - click to enlarge

Click photos to enlarge.

Surveyor's Vernier Compass

Catalogue number:
PH*335209

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

Dimensions:
length 15.5 inches; needle 6 inches

Discussion:

The rim of this compass is graduated to 30 minutes. The variation arc on the south arm extends 20 degrees either way, and is read by folded vernier to 2 minutes. There are two level vials on the north arm, and an outkeeper on the south arm. The side of one vertical sight is graduated to half degrees, for determining angles of elevation or depression. The machine-engraved signature indicates a date of manufacture after 1876. This instrument belonged to Columbia University.

Ref: W. & L. E. Gurley, A Manual of the Principal Instruments Used in American Engineering and Surveying (Troy, N.Y., 1904), pp. 108-120.

Further Information:

Compass
Gurley

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