The primary sphere consists of two wooden circles containg the planetry system around the smallest sphere for the Sun. Fully moveable, these rings are connected by a central axis running from the South to North ecliptic poles and represent MERCURE, VENERIS, LA TERRE (within an earth-moon system), MARTIS and IOVIS. These planetary rings inscribed with information regarding the revolution periods.

Made from hand-coloured lithography, paper, plaster and wood. The maker is unknown , a similar example is currently held in the National Maritime Museums collection of Astronomical and Navigational Instruments. This is a real collectors piece.