NON-IRISH ANTIQUITY : GIRONA FINDS

Astrolabe

The astrolabe was a circular, bronze instrument with graduations in degrees marked round the circle. An arm, or alidade, pivoted in the centre of two crossbars. The astrolabe was hung from a ring at the top and the arm was used to measure the angle of the sun above the horizon at noon. With this information, the ship’s latitude could be calculated using astronomical tables. The Girona astrolabe has lost its calibrations round the circumference. The remains of the suspension loop can be seen at the top of the circle. 'Circular bronze astrolabe with the abraded remains of a suspension loop at the top. The circle is divided in four by cross-members which meet in the centre to form a circular perforated platform on which the sight-rule or alidade, now missing, would have pivoted. The lower cross-member runs into a semicircular weighted base which helped keep the astrolabe verticle when sights were being made. The calibrations on the face of the ring have been obliterated by sea-action over nearly 400 years.' Flanagan, L. 'Ireland's Armada Legacy' (1988) p.63

Northern Ireland: County Antrim: Aird Td.: Lacada Point: Wreck of Girona
Wreck of Girona

BELUM.BGR.155

National Museums NI