The Works of Galileo

Sunspots and Floating Bodies

Ignorance of Mathematics

Galileo believed that mathematicians understood physics better than did physics professors, and he did not hesitate to say so. This 1612 work, Discorso... che Stanno in su l'acqua (Discourse on Floating Bodies) (Figure 1) , demonstrated the ignorance of Lodovico delle Columbe concerning why objects float in water. At a public debate sponsored by the Grand Duke, Galileo vanquished his Aristotelian opponents. Cardinal Maffeo Barbarini was present, and spoke in support of Galileo. Galileo proudly announced that he was not only the Grand Duke’s mathematician, but also his philosopher, which meant natural philosopher, or physicist. This book, printed after the debate at the request of the Grand Duke, is Galileo’s first published work on a topic in physics.

Floating bodies were treated in detail by Archimedes, but because of the disciplinary division between mathematics and physics, Archimedes’ work was largely unknown among university physicists. (Figure 2) (Figure 3)

This book also mentions sunspots; the periods of Jupiter’s satellites; the phases of Venus; and the peculiar shape of Saturn. See Galileo, Discourse on Bodies in Water (Urbana, 1960), trans. Stillman Drake.

Figure 1 Figure 1 - Return to Text

Galileo, 1612, title page.

Zoom - 5 in | 10 in
Download TIFF (large file)
Figure 2 Figure 2 - Return to Text

Galileo, 1612.

Zoom - 5 in | 10 in
Download TIFF (large file)
Figure 3 Figure 3 - Return to Text

Galileo, 1612.

Zoom - 5 in | 10 in
Download TIFF (large file)

Exhibit credit: Kerry Magruder, with the assistance of , Marilyn B. Ogilvie, Duane H. D. Roller.

Exhibit Links
Web Links

These teaching resources provided by the History of Science Department at the University of Oklahoma.

Unless otherwise indicated, all images courtesy History of Science Collections, University of Oklahoma Libraries. Image Terms of Use.

OU LogoOU College of Arts and Sciences Online Logo

OU Disclaimer | Contacts: Content - Kerry Magruder, Website - Eric Bruning