This piece is a reproduction of the Dundee Nautical Astrolabe. This marine astrolabe, made by the Portuguese, is dated between 1550-1555. Its owner, the skipper of a small boat, Andrew Smyton, stamped his name and the date of ownership, 1688. This piece is currently in the Art Gallery and Museum in Dundee.
The nautical astrolabe is the simplification of the planispheric or astronomical astrolabe, and it can only take the height of the stars and was used to calculate latitude.