A wooden pillar 6" (15.2cm) long, 2.2" (5.5cm) dia. with two wooden arms 5.7" (14.5cm) long mounted at right angles at top of pillar. The pillar has a right angled groove cut in its length and fitted with a brass clamp. Each arm is fitted with two small brass sight vanes, one with peep-hole, the other with a hole (threads missing). A brass sight vane with slit is fitted at base of pillar with a brass plate with hole (thread missing) mounted in one of the arms. The same arm carries a brass quadrant 3.25" (8.3cm) radius, which carries three scales, graduated 0-100, 0-100, and 100-0 each by 1 division. Fitted with a brass plate which carries three fiducial edges. A spirit level in a brass casing 2.7" (6.8cm) long is mounted on upper part of quadrant.