This instrument consists of two sets of parallel bars with an elbow joint midway. At one end is a pivot hole to secure to a flat surface. On the other end is a graduated dial, 0-360, with two rules, one on either side of the dial, that can revolve in azimuth. There are also two separate rules, one plastic and others aluminium.
Parallel bars: 26"; 22" (66cm & 56cm)
Circle diameter: 5.5 (14cm)
Rules: 2 x 10", 1 x 14", 1 x 14" (plastic)