Dou's Holland Circle
Graduations- Circle graduated 0-180, 0-180 by 15' and quadrantally in degrees. The alidade has a fiducial edge at each end.
Sights- Two sight vanes 1.5" (3.8cm) long mounted on circle, one sight with a vertical slit, with a rectangular aperture above (threaded), the other with a rectangular aperture (threaded) with a vertical slit above. Two sight vanes 1.5" (3.8cm) long mounted on alidade, similar in description to those on circle. A suspension ring is attached to upper part of circle.
Compass- Dia. 2.75" (7cm) mounted at centre of instrument. Fitted with a narrow blued steel needle 2.25" (5.8cm) long, with abrass pivot cap at centre. Graduated to 16 points, and 0-180, 0-180.
A tube for mounting instrument on tripod is attached at centre of underside .
In black tooled leather case.
Sights- Two sight vanes 1.5" (3.8cm) long mounted on circle, one sight with a vertical slit, with a rectangular aperture above (threaded), the other with a rectangular aperture (threaded) with a vertical slit above. Two sight vanes 1.5" (3.8cm) long mounted on alidade, similar in description to those on circle. A suspension ring is attached to upper part of circle.
Compass- Dia. 2.75" (7cm) mounted at centre of instrument. Fitted with a narrow blued steel needle 2.25" (5.8cm) long, with abrass pivot cap at centre. Graduated to 16 points, and 0-180, 0-180.
A tube for mounting instrument on tripod is attached at centre of underside .
In black tooled leather case.
Object details
| ID: | NAV1372 |
|---|---|
| Type: | Circumferentor |
| Display location: | Not on display |
| Creator: | Unknown |
| Date made: | circa 1650 |
| Credit: | National Maritime Museum, Greenwich, London, Caird Collection |
| Measurements: | 100 mm |