Systema cosmicum. In quo quatuor dialogis, de duobus maximis mundi systematibus, Ptolemaico & Copernicano, utriusque rationibus philosophicis ac naturalibus indefinite propositis differitur

Galileo Galilei's (1564-1642) main physical work Discorsi e Dimostrazioni Matematiche intorno a due nuove scienze could not be published within the sphere of influence of the Roman Catholic Church. Galileo's main physical work was published in 1635 under the title Systema cosmicum by Elsevier and printed in Strasbourg by David Hautti. A print of the Italian text of the Discorsi appeared in 1638 by Elsevier in Leiden.

According to the biography by Galileo's pupil Vincenzo Viviani, Galileo dropped balls of the same material, but different masses, from the Leaning Tower of Pisa to demonstrate that their time of descent was independent of their mass.

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