Exhibition: The Astrolabe, East and West


A terrestrial planisphere

This type of instrument was known as a 'speculum cosmographicum', or 'cosmographical mirror'. It is an astrolabe but with a terrestrial rather than a celestial projection. The earth is shown from the North Pole to the Tropic of Capricorn, and the reduced form of rete can be used, for example, to indicate the time anywhere on earth throughout the year.
Closeup of Geographical Astrolabe, by Gillis Coignet, Antwerp, 1560 (Inv. 53211) showing Antarctica

Geographical Astrolabe, by Gillis Coignet, Antwerp, 1560 (Inv. 53211)
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