Circumferentor
Graduations-Circle graduated to 360 degs. Vernier scale at one end of alidade 0-60.
Sights-Two detachable sight vanes 5.5" (14cm) long mounted on circle, one sight with a vertical slit with a rectangular aperture above ), the other with a rectangular aperture with a vertical slit above. Two detachable sight vanes 5" (12.7cm) long, mounted on alidade, similar in description to those on circle.
Compass- Dia. 5.8" (14.8cm) mounted at centre of instrument. Fitted with a narrow blued steel needle 4.75" (12cm) long, with a brass pivot cap at centre. Graduated to 16 points, quadrantally in degrees and anti-clockwise to 360 degs.
A ball and socket joint for mounting on a tripod is attached to underside.
Sights-Two detachable sight vanes 5.5" (14cm) long mounted on circle, one sight with a vertical slit with a rectangular aperture above ), the other with a rectangular aperture with a vertical slit above. Two detachable sight vanes 5" (12.7cm) long, mounted on alidade, similar in description to those on circle.
Compass- Dia. 5.8" (14.8cm) mounted at centre of instrument. Fitted with a narrow blued steel needle 4.75" (12cm) long, with a brass pivot cap at centre. Graduated to 16 points, quadrantally in degrees and anti-clockwise to 360 degs.
A ball and socket joint for mounting on a tripod is attached to underside.
Object Details
| ID: | NAV1382 |
|---|---|
| Type: | Circumferentor |
| Display location: | Not on display |
| Creator: | Wright, Thomas |
| Date made: | circa 1730 |
| Credit: | National Maritime Museum, Greenwich, London |
| Measurements: | Overall: 250 mm x 314 mm x 310 mm; Diameter: 310 mm |
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