Airship pelorus
An early type of bearing plate or pelorus for use in airships. White metal disc painted black, has graduated dial, quadrantally in degrees, which is set to course steered, against a lubbers arrow. Sights are taken by sight vanes set on a rotating verge ring. Rear sight has slit and two dark shades, fore sight has sighting wire and dark screen for sun bearings, the fore sight is fitted with a V sight and a graduated quadrant so that rough angles of depression to an object on the ground can be obtained.
Mounted in a wooden box. Dimensions 6.75" x 6.75" x 2.25" ( 17.1cm x 17.1cm x 5.8cm)