Bate Surveyor's Vernier Compass

This unusual instrument is marked "Bate London," referring to the London instrument maker, Robert Brettell Bate (1782-1847). 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 counterclockwise from north, and read by vernier to 6 minutes.
Unlike most vernier compasses, 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. A level vial is also mounted below the compass box, and a socket, so that the compass can be used with a jacob staff.
Currently not on view
Bate, Robert Brettell
place made
United Kingdom: England, London
overall: 15 in x 5 1/2 in; 38.1 cm x 13.97 cm
overall: 8.8 cm x 17 cm x 17 cm; 3 7/16 in x 6 11/16 in x 6 11/16 in
overall in case: 3 3/8 in x 6 7/8 in x 6 3/4 in; 8.5725 cm x 17.4625 cm x 17.145 cm
ID Number
accession number
catalog number
See more items in
Medicine and Science: Physical Sciences
Measuring & Mapping
Surveying and Geodesy
Data Source
National Museum of American History