Graphometer in a case. The graphometer is marked NAV1410.1 and can be found via the Whole/Part toggle.
Graduations-Semi-circle graduated 0-180, 180-0 and carries a diagonal scale to 12'. The alidade 9.45" (24cm) long has a fiducial edge, graduated 12-60, at each end. A suspension ring is attached to upper part of semi-circle and there is a straight edge 10.25" (26cm) long at lower part. A square plate 3.75 x 3.75" (9.5 x 9.5cm) is attached to back of instrument.
Sights-Two sight vanes 1.35" (3.5cm) long mounted on straight edge, one sight with a vertical slit with a rectangular aperture above. The other with reverse arrangement. Two sight vanes 1.25" (3.2cm) long mounted on alidade, similar in description to those on straight edge.
Compass-Dia. 2.5" (6.4cm) mounted at centre of instrument. Fitted with a narrow blued steel needle in form of an arrow 2.15" (5.5cm) long, with a brass pivot cap at centre. Graduated to 32 points and to 360 degs.
In shaped black leather case.