A bearing-dial or sun-compass that works on the principle that the tip of the sun's shadow on a gnomon will trace curves that, within specific latitudes and dates, can be used to maintain a course at sea. The principle is that of the sundial.
In 1948, at a Greenland farm ruin that can be traced back to the settlement period of about ad 1000, the Danish archaeologist C. L. Vebaek excavated a half wooden dial with what are taken to be gnomon lines incised on the back and compass points cut around the outer edge. The navigational significance of the find has long been discussed and extensive sea trials have over the years been held using reproduction dials. A curve traced from the shadow of the sun over a whole day can certainly, within certain constraints, provide a means of following a particular direction. The extent to which such a device was adopted by the Norsemen is perhaps more open to question.
Subjects: Maritime History.