User:Mccapra/Discourse on Floating Bodies

Discourse on Floating Bodies (Discorso intorno alle cose che stanno in sù l’acqua o che in quella si mouvono) is a 1612 essay by Galileo Galilei. It was published in Florence and dedicated to duke Cosimo II. The work was his first published contribution to experimental physics. It is unusual for its period because of its combination of descriptions of experiments, mathematics and the more conventional arguments of natural philosophy. It was published in Italian.

Background
In July 1611 a debate about the nature of cold was held at the house of Galileo's friend Filippo Salviati, with two Aristotelians, it:Vincenzo di Grazia and Giorgio Coresio. The Aristotelians held that ice was condensed water, which floated because of its flat, thin shape; Galileo, whose view was informed by Archimedes, maintained that ice was rarified water, which floated because it was less dense than the water supporting it.

As the discussion developed, Galileo took the position that all bodies denser than water sink, while all lighter than water float, regardless of their shape. Three days after this first encounter, di Grazia visited Galileo, and told him that a friend had volunteered to disprove Galileo's position by demonstration. This friend was the leading Aristotelian natural philosopher Lodovico delle Colombe. Galileo signed an agreement setting out the terms of the demonstrations both parties were to prepare, and a date was set for them to meet and present their cases in mid-August at the house of Canon Francesco Nori.

In the days before this proposed meeting, Lodovico delle Colombe took his demonstration to the streets and public places of Florence to show how easily he could prove Galileo wrong. As he showed, a thin strip of ebony floated on water, while a sphere of the same material sank. This, he maintained, showed that shape, not density, determined whether an object would float. However delle Colombe never actually appeared on the agreed day for the planned demonstrations, suggesting that he perhaps understood that his demonstration relied on the particular effects of the surface tension of water rather than on the shapes of his pieces of ebony. Galileo then proposed that they meet on a new date at Salviati's house, and that on this occasion the objects to be placed on the water should all be thoroughly wetted first (which would have removed the surface tension effect). However, when delle Colombe arrived on the appointed day he found that Galileo was unwilling to proceed as they had agreed. Apparently the Grand Duke had rebuked him for involving himself in a vulgar public spectacle, and Galileo therefore said that he would commit his proofs to writing rather than undertake public demonstrations. After this, delle Colombe seems not to have had any further direct role in public debate on this topic. In September Galileo circulated a manuscript outlining his views, but when Cosimo II staged a public debate on the question of floating bodies, it was Flaminio Papazzoni rather than delle Colombe who argued, and lost, against Galileo.

Introduction
The introduction to the essay summarises Galileo’s position on a number of topics not directly related to the physics of floating bodies. What they have in common however is that they all challenge the dominant Aristotelian view of the laws of nature.

Reception
Following the publication of the Discourse on Floating Bodies, delle Colombe swiftly replied with his Discorso Apologetico. Galileo did not reply immediately, and indeed when his reply was published, it was over the name of his friend Benedetto Castelli. Galileo may have felt no useful purpose was served by involving himself directly in this debate, and he may simply not have had the time to respond in detail to all the errors in delle Colombe's book. Castelli was able to produce a thoroughly argued refutation of delle Colombe's points, clearly with help and input from Galileo. Castelli's Risposta alle Opposizioni del S. Lodovico delle Colombe was published in 1615, marking the end of this particular dispute.

https://cen.acs.org/articles/91/i34/Galileo-Ice.html

https://riviste.fupress.net/index.php/subs/article/download/7/8/10

https://galileo.ou.edu/exhibits/discourse-floating-bodies

https://www.museogalileo.it/en/museum/explore/meet-galileo/38-works/465-discorso-intorno-alle-cose-che-stanno-in-sull-acqua-1612.html

https://www.jstor.org/stable/41134201

https://www.journals.uchicago.edu/doi/abs/10.1086/348839?journalCode=isis

The invention of science pp.315-318

https://discovery.ucl.ac.uk/id/eprint/10108851/1/Galileo%27s_mathematical_natural.pdf