Project Gutenberg's Discourse on Floating Bodies, by Galileo Galilei This eBook is for the use of anyone anywhere at no cost and with almost no restrictions whatsoever. You may copy it, give it away or re-use it under the terms of the Project Gutenberg License included with this eBook or online at www.gutenberg.net Title: Discourse on Floating Bodies Author: Galileo Galilei Translator: Thomas Salusbury Release Date: October 12, 2011 [EBook #37729] Language: English Character set encoding: ASCII *** START OF THIS PROJECT GUTENBERG EBOOK DISCOURSE ON FLOATING BODIES *** Produced by Tim Madden and the Online Distributed Proofreading Team at http://www.pgdp.net (This file was produced from images generously made available by The Internet Archive) [Transcriber's Notes All apparent printer's errors retained. Variation in punctuation are as in the original, but missing full stops at end of paragraphs have been supplied. There are inconsistencies in the use of italics, spacing of words and use of full stop after 'AXIOME', abbreviations etc. All are retained to match text. There is a great variation in spelling including multiple spellings of the same word, all spelling has been retained to match text. There are several instances of obviously missing letters or inverted n & u. These have been changed or obvious letters replaced, with the changes surrounded by {}. All instances are detailed at the end of the text. It should also be noted that in the original text there is a missing line at the end of page 24 in original text. There are a number of instances in the original text where 'that' is immediately followed by a second 'that' in the sentence. These could be potential printer's errors or, since several of them make sense, part of the author's style. They have been left in the text as they appear in the original text. The original text has many sidenotes, some are true sidenotes, introductions to paragraphs etc, some acting as footnotes with some marked in original text with *. These have been dealt with in three ways with the footnotes placed after their relevant paragraph and sidenotes place before their relevant paragraph. 1) Footnotes marked with capital letter. These were sidenotes in original text marked with * in the original text and thus acting like footnotes. 2) Footnotes marked with number. These were sidenotes in original text that were unmarked but acting like normal footnotes. The anchor in the text was placed at the most suitable relevant place in comparison with the placement of the sidenote text in the margin, but still should be considered only an approximate placement. 3) Sidenotes placed at start of the relevant paragraph. Some sidenotes were considered not to be relevant as footnotes, introductions to paragraphs etc, and were left as sidenotes before their relevant paragraph.] * * * * * A DISCOURSE _PRESENTED_ TO THE MOST SERENE Don Cosimo II. GREAT DUKE _OF_ TUSCANY, CONCERNING The _NATATION_ of BODIES Vpon, And _SUBMERSION_ In, THE WATER. By GALILEUS GALILEI: Philosopher and Mathematician unto His most Serene Highnesse. Englished from the Second Edition of the ITALIAN, compared with the Manuscript Copies, and reduced into PROPOSITIONS: By _THOMAS SALUSBURY_, Esq; _LONDON_: Printed by WILLIAM LEYBOURN: _M DC LXIII._ * * * * * [Decoration] A DISCOVRSE Presented to the Most Serene DON COSIMO II. GREAT DUKE of _TUSCANY_: CONCERNING _The Natation of BODIES Upon, or Submersion_ _In, the WATER._ Considering (Most Serene Prince) that the publishing this present Treatise, of so different an Argument from that which many expect, and which according to the intentions I proposed in my [A] Astronomicall _Adviso_, I should before this time have put forth, might peradventure make some thinke, either that I had wholly relinquished my farther imployment about the new Celestiall Observations, or that, at least, I handled them very remissely; I have judged fit to render an account, aswell of my deferring that, as of my writing, and publishing this treatise. [A] His Nuncio Siderio. As to the first, the last discoveries of _Saturn_ to be tricorporeall, and of the mutations of Figure in _Venus_, like to those that are seen in the Moon, together with the Consequents depending thereupon, have not so much occasioned the demur, as the investigation of the times of the Conversions of each of the Four Medicean Planets about _Jupiter_, which I lighted upon in _April_ the year past, 1611, at my being in _Rome_; where, in the end, I assertained my selfe, that the first and neerest to _Jupiter_, moved about 8 _gr._ & 29 _m._ of its Sphere in an houre, makeing its whole revolution in one naturall day, and 18 hours, and almost an halfe. The second moves in its Orbe 14 _gr._ 13 _min._ or very neer, in an hour, and its compleat conversion is consummate in 3 dayes, 13 hours, and one third, or thereabouts. The third passeth in an hour, 2 _gr._ 6 _min._ little more or less of its Circle, and measures it all in 7 dayes, 4 hours, or very neer. The fourth, and more remote than the rest, goes in one houre, 0 _gr_ 54 _min._ and almost an halfe of its Sphere, and finisheth it all in 16 dayes, and very neer 18 hours. But because the excessive velocity of their returns or restitutions, requires a most scrupulous precisenesse to calculate their places, in times past and future, especially if the time be for many Moneths or Years; I am therefore forced, with other Observations, and more exact than the former, and in times more remote from one another, to correct the Tables of such Motions, and limit them even to the shortest moment: for such exactnesse my first Observations suffice not; not only in regard of the short intervals of Time, but because I had not as then found out a way to measure the distances between the said Planets by any Instrument: I Observed such Intervals with simple relation to the Diameter of the Body of _Jupiter_; taken, as we have said, by the eye, the which, though they admit not errors of above a Minute, yet they suffice not for the determination of the exact greatness of the Spheres of those Stars. But now that I have hit upon a way of taking such measures without failing, scarce in a very few Seconds, I will continue the observation to the very occultation of _JUPITER_, which shall serve to bring us to the perfect knowledge of the Motions, and Magnitudes of the Orbes of the said Planets, together also with some other consequences thence arising. I adde to these things the observation of some obscure Spots[1], which are discovered in the Solar Body, which changing, position in that, propounds to our consideration a great argument either that the Sun revolves in it selfe, or that perhaps other Starrs, in like manner as _Venus_ and _Mercury_, revolve about it, invisible in other times, by reason of their small digressions, lesse than that of _Mercury_, and only visible when they interpose between the Sun and our eye, or else hint the truth of both this and that; the certainty of which things ought not to be contemned, nor omitted. [1] The Authors Observations of the Solar Spots _Continuall observation hath at last assured me that these Spots are matters contiguous to the Body of the Sun, there continually produced in great number, and afterwards dissolved, some in a shorter, some in a longer time, and to be by the Conversion or Revolution of the Sun in it selfe, which in a Lunar Moneth, or thereabouts, finisheth its Period, caried about in a Circle, an accident great of it selfe, and greater for its Consequences._ As to the other particular in the next place [B] Many causes have moved me to write the present Tract, the subject whereof, is the Dispute which I held some dayes since, with some learned men of this City, about which, as your Highnesse knows, have followed many Discourses: The principall of which Causes hath been the Intimation of your Highnesse, having commended to me Writing, as a singular means to make true known from false, reall from apparent Reasons, farr better than by Disputing vocally, where the one or the other, or very often both the Disputants, through too greate heate, or exalting of the voyce, either are not understood, or else being transported by ostentation of not yeilding to one another, farr from the first Proposition, with the novelty, of the various Proposals, confound both themselves and their Auditors. [B] The occasion inducing the Author to write this Treatise. Moreover, it seemed to me convenient to informe your Highnesse of all the sequell, concerning the Controversie of which I treat, as it hath been advertised often already by others: and because the Doctrine which I follow, in the discussion of the point in hand, is different from that of _Aristotle_; and interferes with his Principles, I have considered that against the Authority of that most famous Man, which amongst many makes all suspected that comes not from the Schooles of the Per...
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