Bearing plate-Dia. 11" (28cm). Brass ring with a heavy pendulum weight on underside. At centre of ring is a glass card 8.75" (22.2cm) dia. with black markings, graduated to 1/4 points and to 360 degs. At centre of card a brass spigot is fitted to which is attached an alidade. Mounted in a black painted brass gimbal ring 12" (30.5cm) dia. attached to stand.
Alidade- Length : 9.5" (24.1cm). Black painted brass bar, the rear sight vane 3.25" (8.2cm) long carries a slit sight and two dark shades, the fore sight 3.25" (8.2cm) long carries an open frame with thread sight and dark glass reflector.
Stand- Dia. of base: 14" (35.6cm), dia. of stand: 6" (15.2cm), dia. of top: 14" (35.6cm). Brown painted brass with door giving access to electric lamp fitting. Hood: brass without apertures.