This celestial planisphere shows the position of the stars on a summer night in the first half of the 17th century. In the centre is the Pole Star. The concentric circles around it are the Polar Circle, the Tropic of Cancer, the Equator and the Tropic of Capricorn. The broad brass belt is engraved with the signs of the zodiac. The main constellations, like Ursa Major and Ursa Minor, used to be labelled with brass nameplates, but most of these have disappeared.
Here and there, fragments of constellations can still be made out. They include the club of Hercules, the sword of Perseus, the chains and fetters of Andromeda, the arms of Libra, and the head, pincers and legs of Scorpio.