Graduations-Semi-circle graduated 0-180, 180-0 . The alidade 7.5" (19cm) long has a fiducial edge at each end. A suspension lug is attached to upper part of semi-circle and there is a straight edge 8.2" (20.8cm) long at lower part. A ball and socket and a square plate 2.7 x 2.7" (6.8 x 6.8cm) are attached to back of instrument.
Sights-One sight vane 1.25" (3.1cm) long mounted on straight edge, it has a rectangular aperture with sighting strip and with a vertical slit above. Two sight vanes 1.25" (3.2cm) long mounted on alidade, similar in description to that on straight edge.
Compass-Dia. 2." (5cm) mounted at centre of instrument. Fitted with a tapered flat bar needle 1.5" (3.8cm) long, with a brass pivot cap at centre. Graduated to 16 points and to 360 degs.
In shaped black leather case lined with green baize.