Graduations-Semi-circle graduated 0-180, 180-0. The alidade 8.55" (21.8cm) long has a fiducial edge at each end. A suspension lug (with ring and swivel) is attached to upper part of semi-circle and there is a straight edge 9.9" (25.1cm) long at lower part. A ball and socket head and a square plate 3.55 x 3.55" (9 x 9cm) are attached to back of instrument.
Sights-Two sight vanes 1.5" (3.8cm) long mounted on straight edge, one sight with a vertical slit with a rectangular aperture above (complete with brass sighting strip). The other with reverse arrangement. Two sight vanes 1.4" (3.5cm) long mounted on alidade, similar in description to those on straight edge.
Compass-Dia. 2.75" (7cm) mounted at centre of instrument. Fitted with a tapered flat bar needle in form of an arrow 2.2" (5.5cm) long, with a brass pivot cap at centre. Graduated to 8 points and to 360 degs.
In a shaped black leather case lined with green baize.