A circular ring fitted to the rim of a compass bowl and carrying two sighting vanes, used to take azimuths of celestial objects. The ring can be easily revolved and the compass bearing read off by sighting the vanes on the required object. Alternatively, the ring can be fitted to a ‘dumb’ compass (without a directive element) which can be set by hand to the course of the ship before taking a bearing.
The word comes from the name of Hannibal's pilot, probably a Greek, who sided with the Carthaginians, assisted Hannibal to get his troops across to Europe, and kept him in touch with Carthage by sea.
Subjects: Maritime History — Warfare and Defence.