A fairly complex, multi-purpose instrument. The front compartment contains an astrolabe and a geographic mirror engraved with the name of the maker, Hans Christoph Schissler. The back compartment has a magnetic compass that can be oriented horizontally, with a calendar on the outer side of the compass base. There are also a diopter with a graduated scale for measuring heights and a plumb bob for measuring slopes. All these items fitted into a gold-tooled leather box. Brought to Florence from Germany by Prince Mattias de' Medici in the first half of the seventeenth century.