Cosmographia is a remarkable book from many standpoints. The book is rich source of illustrations of instruments and contains instructions for their use. The instruments shown in Cosmographia were mathematical instruments. These instruments, like cosmography itself, were not seen to yield information about the function of the natural world. Mathematical instruments were used only for measurement and calculation— of time, the heights of towers at a distance or the relative angular positions of stars and planets. Not until the 17th century were instruments used for more than measurement, when they were employed in natural philosophy experiments.

In addition to illustrations and descriptions of wooden, brass and ivory instruments, Cosmographia contains full-page, working paper instruments known as volvelles. Volvelles are rotating paper devices that perform calculations for solving problems of the calender or the positions of the sun, moon and other planets. Volvelles were not uncommon in 16th century books and trace their origins back to earlier manuscripts.

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