Why is an Atlas called an Atlas?

Atlas is the term used to refer to a collection of maps, printed in a set order: world map, maps of the continents, each followed by maps of the several regions within that continent, and with an alphabetical gazetteer or list of place names, giving coordinates for various places, rivers, regions etc. The first use of the term atlas dates back to 1595 with the publication in Duisburg of the Atlas Sive Cosmographicae Meditationes de Fabrica Mundi et Fabricati Figura by Gerard Mercator (1512-94). It was named after King Atlas, a mythical King of Mauretania in Libya, who was, according to legend, a wise philosopher, mathematician and astronomer and who supposedly made the first celestial globe. However, the more widely known Atlas is a figure from Greek mythology. He is the son of the Titan Iapetus and Clymene (or Asia), and brother of Prometheus. Atlas was punished by Zeus and made to bear the weight of the heavens and Earth on his back.