The University of Sydney - Rare Books & Special Collections Library 

Apianus' Cosmographia is a modification of his earlier work Astronomicum caesarium, one of the finest astronomical works ever produced. Its scientific importance is considerable. It contains information on comets, with the first illustration of the discovery that their tails always point away from the sun as well as a broad treatment of Ptolemaic astronomy.

Of particular importance to note is the size of the work. It is a truly portable book, far removed from the stately folios of the 15th century and clearly designed for personal, individual use.

It is of interest also because of its illustrations with their accompanying volvelles. These are composiyte woodcut diagrams with moveable parts, usually superimposed circles or segments of a circle, bearing printed information. Volvelles were often used to provide astrological as well as scientific information. They could be used for a wide range of calculations, such as charting the critical days in the course of an illness, or determining the longitude of a planet. Very few books of this type survive with the volvelles intact but they provide a good example of the ways in which scientific thought was applied to the solving of problems.