NavList:

Greg wrote: Attached is an image of an Azimuth Circle which is placed over a gyro repeater on the bridge wing. A small adjustable mirror directs the Sun image into a prism which redirects the light onto the compass card for a reading. The gyro repeater needs to be kept level using bubble levels through the process.

Greg.  I’d seen photographs.  I’ve even got a photograph of my dad standing behind the magnetic compass binnacle in the monkey island of his ship with one hand on each of the soft iron balls, but I’ve never looked at it closely before.  I never realised you could take bearings with the ring on objects other than ones in the approximately horizontal plane.  Therein is an area where aeronautical GM compasses and repeaters diverge from nautical ones.  The need to save space and save the pilot or navigator looking down meant that most aircraft GM compasses and repeaters soon acquired vertical faces preventing the use of any clever add-ons. Dave