Nautical astrolabe (used to find latitude measuring Sun and stars height). Called "Valence astrolabe", 16th century. Original on Greenwich National Maritime Museum and copy on Museo Naval de Madrid.
The nautical astrolabe is simplified to measure the altitude of the stars for purposes of navigation. It's heavier construction from those used on land was to compensate for the movement of the vessel at sea.
This beautiful instrument is made of brass and comes complete with wooden base and booklets explaining its use and historical context.
Max Height: 5.91"