What was Cosmographia and why was it so popular? Petrus Apianus was a German mathematician and instrument maker. The first edition of Cosmographia appeared in 1524 to moderate success. Essentially a mathematical treatise, Cosmographia provided a layman's introduction to such subjects as astronomy, geography, cartography, surveying, navigation and mathematical instruments. Revised and enlarged by the Flemish instrument maker Gemma Frisius over the next ten years, Cosmographia became an early 'bestseller' in the first century of print publishing. 
Text from the frontispiece of Cosmographia 

The title Cosmographia indicates a now unfamiliar discipline called cosmography. Until modern times, the study of the universe was split between cosmology on one hand and cosmography on the other. As their names suggest, both subjects were universal in scope. However, where cosmology sought to explain philosophically how the universe works, cosmography looked only to describe how the universe is laid out. Cosmography aimed to mathematically map the entire universe: stars, planets, sun, moon, oceans, continents and countryside. This ambitious mapping program involved the conjunction of several seemingly disparate mathematical disciplines including astronomy, astrology, cartography, navigation, surveying, dialing (the making of sun dials), architecture and instrument making. 
Mapping the celestial sphere 

