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

Click photos to enlarge.

Surveyor's Vernier Compass

Catalogue number:
PH*319793.1

Inscriptions:
"Bate London"

Dimensions:
Diameter 5.5 inches; length 15 inches

Discussion:
This is an unusual instrument. The outer edge of the face is graduated to 10 degrees, and numbered from north and south. The rim is graduated to single degrees, numbered counter clockwise from north, and read by vernier to 6 minutes. Unlike most vernier compasses, however, this one has no variation arc. And unlike most surveyor's compasses, here the sight vanes are attached to the arms, and the arms screw onto the compass box. There is also a level vial mounted below the compass box, and a socket so that the compass can be used with a jacob staff. This instrument dates from the first half of the 19th century, when Robert Brettell Bate was working in London.

Further Information:

Surveyor's Compass
Bate

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