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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

Surveyor's Vernier Compass - click to enlarge

Click photos to enlarge.

Surveyor's Vernier Compass

Catalogue number:
PH*335210

Inscriptions:
"W. & L. E. Gurley" and 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 seconds. There is an outkeeper on the south arm, and two level vials on the north. The hand-engraved signature indicates a date of manufacture between 1852 and 1876. This instrument belonged to Columbia University. New, it cost $50.

The compass is equipped with a telescope that attaches to one of the sight vanes, and that is marked "W. & L. E. GURLEY, TROY, N.Y. PATENTED JULY 9, 1878." The reference is to patent #205,712 describing an Improvement in Telescope Attachments for Surveyors’ Compasses, and granted to William Gurley and Lewis E. Gurley.

Ref: W. & L. E. Gurley, A Manual of the Principal Instruments Used in American Engineering and Surveying (Troy, N.Y., 1871), pp. 23-27.

Further Information:

Gurley
Compass

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