Dimension L: 7 W: 7 H: 11.5 Inches About This is a replica of a European Demonstrational Armillary Sphere. It was used to measure the relationships of the objects in the sky. Each piece is made of finely crafted brass. It consists of a set of graduated rings representing circles on the celestial sphere. The brass sphere at the center of the armillary represents the Earth. The rims are marked "A PARIS Chez G. Gobille a P Ache Royalle." It features a rich antique finish that does not tarnish or show fingerprints. The heavy solid brass base is mounted on turned solid hardwood, and the bottom is covered with felt. Its a great addition to any nautical collection. The item dimensions are: L: 7 inches, W: 7 inches, H: 11.5. History Armillary spheres have become an icon of science with their elegant rings and beautiful silhouettes. Eratosthenes may have invented armillary spheres around 255 BC. These instruments are made up of a set of graduated rings representing circles on the celestial sphere, such as the meridian, equator, ecliptic horizon, tropics, and colures. With the aid of an armillary sphere, one can track the path of the sun for any given day of the year or determine a stars coordinates. The Earth is represented by the brass sphere located at the center of the armillary sphere.