GALILEO ENGINEER

BOSTON STUDIES IN THE PHILOSOPHY OF SCIENCE

VOLUME 269

Editors

ROBERT S. COHEN, Boston UniversityJÜRGEN RENN, Max Planck Institute for the History of Science

KOSTAS GAVROGLU, University of Athens

Editorial Advisory Board

THOMAS F. GLICK, Boston UniversityADOLF GRÜNBAUM, University of PittsburghSYLVAN S. SCHWEBER, Brandeis University

JOHN J. STACHEL, Boston UniversityMARX W. WARTOFSKY†, (Editor 1960–1997)

For further volumes:http://www.springer.com/series/5710

GALILEO ENGINEER

by

MATTEO VALLERIANIMax Planck Institute for the History of Science

Berlin, Germany

123

Matteo VallerianiMax Planck Institute for the History of ScienceBoltzmannstr. 2214195 BerlinGermanyvalleriani@mpiwg-berlin.mpg.de

Dissertation zur Erlangung des Doktorgrades an der Philosophischen Fakultät I der HumboldtUniversität zu Berlin.

ISBN 978-90-481-8644-0 e-ISBN 978-90-481-8645-7DOI 10.1007/978-90-481-8645-7Springer Dordrecht Heidelberg London New York

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Carlo de Bonardis (17th century). Scientist undertaking an experiment. Oil painting(Bona Castellotti, Gamba et al. 1999/2000, 141)

Contents

Foreword: The Historical Epistemology of Mechanics . . . . . . . . . . xiJürgen Renn

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv

Part I War and Practice

1 Artist-Engineers’ Apprenticeship and Galileo . . . . . . . . . . . . . 3The Political and Economic Context . . . . . . . . . . . . . . . . . . . 3The Education of Artist-Engineers . . . . . . . . . . . . . . . . . . . . 7Galileo’s Apprenticeship . . . . . . . . . . . . . . . . . . . . . . . . . 12From the Apprenticeship to the Workshop via the University . . . . . . 15The Buzz of the Workshop . . . . . . . . . . . . . . . . . . . . . . . . 19

2 Instruments and Machines . . . . . . . . . . . . . . . . . . . . . . . 21Galileo’s Balance Sheet . . . . . . . . . . . . . . . . . . . . . . . . . . 24The Production and Organization of the Workshop . . . . . . . . . . . . 26The Military Compass . . . . . . . . . . . . . . . . . . . . . . . . . . . 27The Reduction Compass . . . . . . . . . . . . . . . . . . . . . . . . . 38The Surveying Compass . . . . . . . . . . . . . . . . . . . . . . . . . 39Other Instruments and Tools . . . . . . . . . . . . . . . . . . . . . . . 41Lenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41Glass Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48Adapting the Telescope for other Optical Devices . . . . . . . . . . . . 53Mirrors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60Machine for Pounding Gunpowder . . . . . . . . . . . . . . . . . . . . 66Machine for Lifting Heavy Weights . . . . . . . . . . . . . . . . . . . 67Water Lifting Machine . . . . . . . . . . . . . . . . . . . . . . . . . . 68Galileo as a Military Engineer . . . . . . . . . . . . . . . . . . . . . . 69

3 Galileo’s Private Course on Fortifications . . . . . . . . . . . . . . . 71The Structure of the Business . . . . . . . . . . . . . . . . . . . . . . . 72Mathematics for the Military Art . . . . . . . . . . . . . . . . . . . . . 75Military Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . 77Artillery Powered by Gunpowder . . . . . . . . . . . . . . . . . . . . . 86

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La sfera . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89The Science of Machines . . . . . . . . . . . . . . . . . . . . . . . . . 91Compounds of Simple Machines to Multiply Force . . . . . . . . . . . 104Compound Machines Useful in the Fortress . . . . . . . . . . . . . . . 108The Art of War and the Materiality of Machines . . . . . . . . . . . . . 112

Part II Practice and Science

4 The Knowledge of the Venetian Arsenal . . . . . . . . . . . . . . . . 117Dating Galileo’s Work on the Science of Materials . . . . . . . . . . . . 120The Key Question of the Machine Makers . . . . . . . . . . . . . . . . 120Galileo’s Cantilever Model . . . . . . . . . . . . . . . . . . . . . . . . 122The Origins of the Renaissance Engineers’ Cantilever Model . . . . . . 124Galileo at the Arsenal: The Aristotelian Nautical Questions . . . . . . . 132Did the Venetian Arsenal Employ Galileo? . . . . . . . . . . . . . . . . 138Galileo’s Apprenticeship as a Proto . . . . . . . . . . . . . . . . . . . . 140Galileo’s Masterpiece: The Oar Model . . . . . . . . . . . . . . . . . . 150Did Galileo Become a Proto? . . . . . . . . . . . . . . . . . . . . . . . 152

5 Pneumatics, the Thermoscope and the New AtomisticConception of Heat . . . . . . . . . . . . . . . . . . . . . . . . . . . 155The Thermoscope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158The Emergence of the Thermoscope . . . . . . . . . . . . . . . . . . . 160From the Thermoscope to the Thermometer . . . . . . . . . . . . . . . 165Empirical Data Provided by the Thermoscope . . . . . . . . . . . . . . 169The Reception of Ancient Pneumatics . . . . . . . . . . . . . . . . . . 172Galileo as a Pneumatic Engineer . . . . . . . . . . . . . . . . . . . . . 178The Functioning of the Thermoscope . . . . . . . . . . . . . . . . . . . 181Galileo’s Doctrine of Heat . . . . . . . . . . . . . . . . . . . . . . . . 186The Generation of a Heat Doctrine . . . . . . . . . . . . . . . . . . . . 190

Part III The Engineer and the Scientist

6 Was Galileo an Engineer? . . . . . . . . . . . . . . . . . . . . . . . . 193Revolution of the Art of War . . . . . . . . . . . . . . . . . . . . . . . 193Galilei in the Current of Warfare . . . . . . . . . . . . . . . . . . . . . 197Beyond Engineering . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199The Aristotelian Engineer . . . . . . . . . . . . . . . . . . . . . . . . . 203Generation of Knowledge . . . . . . . . . . . . . . . . . . . . . . . . . 206Engineer-Scientists . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207

Sources: Galileo’s Correspondence . . . . . . . . . . . . . . . . . . . . . 213Notes on the Translations . . . . . . . . . . . . . . . . . . . . . . . . . 213Galileo to G. Contarini in Venice. Padova, March 22, 1593 . . . . . . . 214G. Contarini to Galileo in Padova. Venice, March 28, 1593 . . . . . . . 216Galileo to A. Mocenigo in Venice. Padova, January 11, 1594 . . . . . . 219G. Sagredo to Galileo in Padova. Venice, January 17, 1602 . . . . . . . 221

Contents ix

G. Sagredo to Galileo in Padova. Venice, August 23, 1602 . . . . . . . . 222Galileo to A. de’ Medici in Florence. Padova, February 11, 1609 . . . . 223G. Bartoli to B. Vinta in Florence. Venice, September 26, 1609 . . . . . 225M. Hastal to Galileo in Florence. Prague, August 24, 1610 . . . . . . . 226D. Antonini to Galileo in Florence. Brussels, February 4, 1612 . . . . . 227G. Sagredo to Galileo in Florence. Venice, June 30, 1612 . . . . . . . . 229G. Sagredo to Galileo in Florence. Venice, May 9, 1613 . . . . . . . . . 231G. Sagredo to Galileo in Florence. Venice, July 27, 1613 . . . . . . . . 233G. Sagredo to Galileo in Florence. Venice, August 24, 1613 . . . . . . . 234G. B. Baliani to Galileo in Florence. Genoa, April 4, 1614 . . . . . . . . 238G. F. Sagredo to Galileo in Florence. Venice, February 7, 1615 . . . . . 239G. F. Sagredo to Galileo in Florence. Venice, March 15, 1615 . . . . . . 241G. F. Sagredo to Galileo in Florence. Venice, April 11, 1615 . . . . . . 244B. Castelli to Galileo in Florence. Pisa, May 24, 1617 . . . . . . . . . . 248Galileo to Leopold of Austria in Innsbruck. Florence, May 23, 1618 . . 250G. F. Sagredo to Galileo in Florence. Morocco, August 4, 1618 . . . . . 252G. F. Sagredo to Galileo in Florence. Venice, August 18, 1618 . . . . . 255G. F. Sagredo to Galileo in Bellosguardo. Venice, October 27, 1618 . . 256G. F. Sagredo to Galileo in Florence. Venice, November 3, 1618 . . . . 257G. F. Sagredo to Galileo in Florence. Venice, December 22, 1618 . . . . 259G. F. Sagredo to Galileo in Bellosguardo. Venice, March 30, 1619 . . . 260G. C. Lagalla to Galileo in Florence. Rome, July 30, 1621 . . . . . . . . 263G. B. Guazzaroni to Galileo in Aquasparta. Todi, April 20, 1624 . . . . 264Galileo to F. Cesi in Rome. Bellosguardo, September 23, 1624 . . . . . 266G. di Guevara to Galileo in Florence. Teano, November 15, 1627 . . . . 268A. Arrighetti to Galileo in Siena. Florence, September 25, 1633 . . . . . 270Galileo to A. Arrighetti in Florence. Siena, September 27, 1633 . . . . . 273N. Aggiunti to Galileo in Florence. Pisa, February 22, 1634 . . . . . . . 274F. Micanzio to Galileo in Florence. Venice, July 8, 1634 . . . . . . . . . 276A. de Ville to Galileo in Arcetri. Venice, March 3, 1635 . . . . . . . . . 277F. Micanzio to Galileo in Florence. Venice, December 1, 1635 . . . . . 284B. Cavalieri to Galileo in Arcetri. Bologna, March 11, 1636 . . . . . . . 285Galileo to L. Reael in Amsterdam. Arcetri, June 5, 1637 . . . . . . . . . 288Galileo to F. Micanzio in Venice. Arcetri, November 20, 1637 . . . . . . 295

Credits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 297

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299Galileo’s Works . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299Primary Literature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301Secondary Literature . . . . . . . . . . . . . . . . . . . . . . . . . . . 306

Name Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315

Illustration Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 319

Foreword: The Historical Epistemologyof Mechanics

Jürgen Renn

The historical epistemology of mechanics studies the long-term developmentof mechanical knowledge. Mechanical knowledge concerns material bodies intime and space, their motions, and the forces that cause or resist such motions.Mechanical knowledge enables us to predict how bodies change their positionwith time as long as we know their current state and the forces acting uponthem. Mechanical knowledge of this kind played a special role in the processof transformation from natural philosophy to modern science. Natural philos-ophy from its very inception in the works of Aristotle constructed conceptualsystems to represent pictures of the world as a whole. But, in contrast to suchglobal intentions, the origins of mechanical knowledge have to be sought in themuch more down-to-earth practical activities of achieving the specific tasks ofeveryday life.

Over a long historical period, the development of mechanical knowledge andits transmission from one generation to the next remained an inherent dimensionof such activities, unrelated to any cognitive endeavors aimed at constructing amechanical worldview. It was only after the first attempts in classical antiquityto include mechanical knowledge in the conceptual systems of natural philoso-phy that its assimilation to them and the corresponding accommodation of suchsystems to mechanical concepts led to conflicts between mechanical knowledgeand knowledge about nature as a whole. It was only after the growing body ofmechanical knowledge became a vital resource of early modern societies thatmechanical knowledge within its own conceptual systematization started to competewith natural philosophy by constructing its own worldviews. This finally resultedin early modern times in what has been called the “mechanization of the worldpicture.”

The main goal of the series under the heading The Historical Epistemology ofMechanics, conceived in analogy to the four-volume set on The Genesis of GeneralRelativity, is to explain the development and diffusion of mechanical knowledgein terms of historical-epistemological concepts. The studies presented within theseries are based on a research project centered at the Max Planck Institute for theHistory of Science in Berlin. While the emphasis of the research has been on theperiod of the Scientific Revolution, the analysis also takes into account the long-term

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development of mechanical knowledge without which neither its emergence nor theconsequences of this period can be adequately understood. Just as the reconstructionof the relativity revolution in The Genesis of General Relativity takes Einstein’swork as the point of reference for a thorough contextualization of his achieve-ments, the reconstruction of the transformation of mechanical knowledge duringthe Scientific Revolution similarly refers to Galileo’s work as a point of departurefor outlining a historical epistemology of mechanics.

The development of an adequate theoretical framework provides a common basisfor the investigations constituting The Historical Epistemology of Mechanics. Thelongevity of mechanics makes it particularly clear that large domains of humanknowledge accumulated by experience are not simply lost when theories are revised,even if this knowledge does not explicitly appear in such theories. Thus formallogic is of little use for a description of the multi-layered architecture of scien-tific knowledge that allows both the continuous and the discontinuous aspects ofthe transmission of mechanical knowledge to be accounted for. In order to explainstructural transformations of systems of knowledge, it is furthermore necessaryto take into account the collective character and the historical specificity of theknowledge being transmitted and transformed, as well as to employ sophisticatedmodels for reconstructing processes of knowledge development. Concepts suchas “mental model”, “shared knowledge”, “challenging object”, and “knowledgereorganization” have turned out in our work to be pivotal for such explanations.

We conceive of mental models as knowledge representation structures based ondefault logic, which allow inferences to be drawn from prior experiences aboutcomplex objects and processes even when only incomplete information on them isavailable. Mental models relevant to the history of mechanics either belong to gener-ally shared knowledge or to the shared knowledge of specific groups. Accordingly,they can be related either to intuitive, to practical, or to theoretical knowledge. Theyare, in any case, characterized by a remarkable longevity—even across historicalbreaks—as becomes clear when considering examples such as the mental modelsof an atom, of a balance, of the center of gravity, or of positional weight. Theirpersistence in shaping the shared knowledge documented by the historical sourcesbecomes particularly apparent in the consistency of the terminology used, a consis-tency that offers one important element for an empirical control in the reconstructionof mental models and their historical development. The concept of mental model isparticularly suited to study the role of practical knowledge for the transformation ofmechanics in the early modern period.

We conceive of challenging objects as historically specific material objects,processes or practices entering the range of application of a system of knowl-edge without the system being capable of providing a canonical explanation forthem. Examples run from mechanical devices challenging Aristotelian dynamics,via artillery challenging early modern theories of motion, to black body radiationchallenging classical radiation theory. In reaction to such challenges, knowledgesystems are typically further elaborated, occasionally to the extent that they give riseto internal tensions and even inconsistencies. Such explorations of their limits maythen become starting points for their reorganization where often previously marginal

Foreword: The Historical Epistemology of Mechanics xiii

insights take on a central role in an emerging new system of knowledge. Suchprocesses of reorganization may be exemplified by the emergence of theoreticalmechanics from Aristotelian natural philosophy in ancient Greece, the transforma-tion of preclassical into classical mechanics in early modern times, or the emergenceof quantum theory from classical physics at the turn of the last century.

The investigations constituting The Historical Epistemology of Mechanics buildon this theoretical framework, centering on the role of shared knowledge, ofchallenging objects, and of knowledge reorganization. The first study, MatthiasSchemmel’s The English Galileo: Thomas Harriot’s Work on Motion as an Exampleof Preclassical Mechanics, has investigated the shared knowledge of preclassicalmechanics by relating the work of Thomas Harriot on motion, documented by awealth of manuscripts, to that of Galileo and other contemporaries. While the pathsHarriot traces through the shared knowledgeare different from Galileo’s, the work ofthe two scientists displays striking similarities as regards their achievements as wellas the problems they were unable to solve. The study of Harriot’s parallel work hasthus allowed the exploration of the structure of the shared knowledge of early mod-ern mechanics, to perceive possible alternative histories, and to distinguish betweenindividual peculiarities and shared structures of early modern mechanical reasoning.

This volume, Galileo Engineer, the second study of the series, looks more closelyat the role of Galileo as a practical mathematician and engineer-scientist. It focuseson his intellectual development in the frame of the interaction between naturalphilosophy and the challenging objects provided by technological developments.It analyzes Galileo’s contribution to the practical science of machines as well ashis role as a teacher involved in the contemporary art of war. The results of thisanalysis highlight Galileo’s profile as a military engineer. By means of two casestudies this book develops a model according to which new scientific knowledge wasgenerated on the basis of the interaction between theoretical knowledge—basicallyAristotelian—and the practical knowledge Galileo shared with his contemporaries.The first case study concerns Galileo’s theory of the strength of materials, namelythe first of his Two New Sciences, and its relation to the practical knowledge of theVenetian Arsenal. The second case study concerns the emergence of Galileo’s heatdoctrine on the basis of the practical knowledge related to pneumatics. Galileo’swork is finally reinterpreted in its entirety against the background of a historio-graphical investigation concerning the early modern figure of the engineer-scientist,which concludes this book.

A subsequent contribution to this series will look more closely at the reorgani-zation of mechanical knowledge that took place in the course of Galileo’s researchprocess stimulated by contemporary challenging objects. A further study will artic-ulate more extensively the theoretical foundations of a historical epistemology ofmechanics, providing an outline of the long-term development of mechanical knowl-edge. The theoretical framework adopted makes it possible to analyze and makeexplicit the relations between diverse forms of mechanical knowledge which havehitherto been mostly treated in isolation from each other. Among these differ-ent forms is the intuitive knowledge gained through basic material activities, thepractical knowledge of professionals, and the theoretical knowledge resulting from

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the reflection of various forms of knowledge in the context of scientific theories.On this basis it should be possible to reconstruct the long-term development ofmechanical knowledge from its anthropological origins via the formation of amechanical world view to the understanding of material interactions within theframework of quantum mechanics and of the space-time geometry of modernphysics.

Introduction

Galileo Galilei (1564–1642), his life and his work have been and continue tobe the subject of an enormous number of scholarly works. One of the conse-quences of this is the proliferation of identities bestowed on this figure of the ItalianRenaissance: Galileo the great theoretician, Galileo the keen astronomer, Galileothe genius, Galileo the physicist, Galileo the mathematician, Galileo the solitarythinker, Galileo the founder of modern science, Galileo the heretic, Galileo thecourtier, Galileo the early modern Archimedes, Galileo the Aristotelian, Galileothe founder of the Italian scientific language, Galileo the cosmologist, Galileo thePlatonist, Galileo the artist and Galileo the democratic scientist. These may be onlya few of the identities that historians of science have associated with Galileo. Andnow: Galileo the engineer!

That Galileo had so many faces, or even identities, seems hardly plausible. But byfocusing on his activities as an engineer, historians are able to reassemble Galileo ina single persona, at least as far as his scientific work is concerned. The impressionthat Galileo was an ingenious and isolated theoretician derives from his scientificwork being regarded outside the context in which it originated. Thanks to a series ofhistorical research works dedicated to case studies and to a certain historiographicaltradition that began in the 1920s, represented chiefly by Leonardo Olschki (Olschki1919–1927), it has been possible to infer that Galileo’s practical activities, that is,his engagement in the practical knowledge of his time, played a significant role inhis scientific speculations. A relevant case study that confirms such an inferenceconcerns Galileo’s achievement of the formulation of the law of fall. In this case,it has been shown how Galileo’s theoretical investigations were directly connectedto the knowledge of early modern artillerists (Renn et al. 2001), and thus that themain building block of Galileo’s new science of dynamics was rooted in their prac-tical knowledge (Damerow et al. 2004). Another case study was able to show howrelevant aspects of Galileo’s hydrostatics, published in his Floating Bodies in 1612,were directly connected to metallurgy and, specifically, to the practice of bell casting(Valleriani 2008). The practical knowledge that Galileo shared thus appears to be themost suitable guide for contextualizing his theoretical speculations. In consequenceof these considerations the hypothesis emerged that Galileo’s science, in general, is

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rooted in the practical knowledge of his time.1 Accordingly Pamela Smith arguedin favor of a conception of new early modern science as first “disseminated andinculcated” in the workshops of the artisans (Smith 2004, 240).

To investigate in such a direction, both a general definition of practical knowl-edge and a historiographical determination of those who produced it and were activein its framework are needed. This work makes use of a definition of artist-engineerformulated on the basis of Edgar Zilsel’s The Social Origins of Modern Science(Zilsel 2000).2 Zilsel defined the Renaissance artist-engineer mainly on the basisof his analysis of the training of famous engineers, architects and artists. He foundsimilarities in the training curricula for these professions and formulated the the-sis that an artist, engineer or architect became such after an apprenticeship, basedon the work he was commissioned to perform, and on his success in completinga project that embraced either engineering, architecture or art. Zilsel’s thesis con-tributes to clarifying the tendency in Renaissance culture not to consider these asseparate fields of activity, and therefore forces the contemporary historian to turn toa later period to seek and understand, for example, the process that led to a view ofthe artist as apparently and completely removed from the technological developmentof his era.3

One relevant phenomenon of the early modern period, and especially of Galileo’stime, was the huge increase in textual output as result of a process of codify-ing practical knowledge. These texts mostly contained the knowledge of militaryengineers and architects, machine makers, makers of mathematical instruments andshipwrights. The texts, together with manuscripts and books on subjects such astheatrical machinery, trick fountains, automata, metallurgy, instruments, mechani-cal tools, and practical optics, constitute a considerable portion of the entire textualproduction of the age. The knowledge codified in these writings, together with theknowledge integrated directly into the results of their practical implementation, suchas cathedrals, milling devices, galleys, tools and instruments, many of which wereleft behind by those who never wrote a treatise, constitutes this work’s definition ofpractical knowledge.

Until now no systematic research has ever been undertaken that aims to showhow Galileo’s interactions with the practical knowledge of his time were more orless intensive and fruitful by taking the entire spectrum of his practical activitiesinto consideration rather than just a selection. This work aspires to present sucha panoramic view. In accomplishing this goal, however, the level of generaliza-tion implied in the leading hypothesis had to be abandoned. This work followsGalileo through the main phases of his life—his time in Florence, in Pisa, in Padovaand his subsequent return to Florence, but it is also organized thematically in

1Thomas Kuhn also formulated such an encompassing hypothesis. However, he did not investigatethe reasons for such a statement (Kuhn 1976, 55–56).2Zilsel’s book was originally published in German in 1976.3For an exhaustive analysis of the historiographical consequences of Zilsel’s thesis, see Valleriani(2009b, especially 116–117).

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accordance with the specific activities Galileo undertook. According to this plan-ning, the space-time area on which this research focuses narrows to the Italianpeninsula in the period that includes the second half of the sixteenth and the firsthalf of the seventeenth centuries.

Each of the practical activities undertaken by Galileo and all of the aspects ofpractical knowledge shared by Galileo are analyzed starting from historical evidencesuch as Galileo’s personal and administrative documents. His correspondence, ascollected and published by Antonio Favaro,4 plays a major role. The lives andworks of relevant correspondents and, in particular, their relations with Galileo, arethen considered on the basis of the leading hypothesis of this work. Concerning thesubjects discussed, the state of the specific practical knowledge involved is investi-gated in greater detail, mainly by means of treatises compiled by experts in variouspractical activities, as contemporary to Galileo as possible. A comparison betweenGalileo’s arguments and those of such experts, to the extent that these can be inferredfrom their treatises and material works, reveals the intensity of Galileo’s practicalactivity in each of the fields in which he was involved, and finally the “degree” towhich he utilized the practical knowledge of his day. This analysis is performedfor each kind of practical activity undertaken by Galileo. Galileo’s major publishedworks, finally, are related to those activities as well. Thus, the traditional historicalapproach to Galileo, which begins with his major publications, is reversed. All ofthe letters which play a decisive role in this work have therefore been appended inthe author’s English translation.

According to this method, the work turns out to have two main protagonists: thefirst is Galileo, while the other is practical knowledge, or rather those who embodiedand implemented it. Although the principal aim of this book is to approach Galileo’swork from the perspective of the practical knowledge, Galileo himself can be usedas a lantern to elucidate the state of the art and, in general, the structure of prac-tical knowledge between the second half of the sixteenth and the first half of theseventeenth century, as well as for other activities in which Galileo participated.

Structure of the Book

The book is divided into three main parts. The first—War and Practice—aims toshow how Galileo followed the typical educational path of the artist-engineer inthe second half of the sixteenth century and, finally, how he consequently beganhis career and retained the profile of a military engineer. The second part—Practiceand Science—comprises two major case studies that are able to show how particulartheoretical developments of Galileo are rooted in the practical knowledge of his

4Galileo’s works were published several times in the form of Opera omnia before Antonio Favaroedited Le opere di Galileo Galilei in twenty volumes between 1890 and 1909. This is still the stan-dard work used by scholars today. The second edition of Favaro’s collection (1968) is used in thepresent work and quoted with the abbreviation EN (Edizione Nazionale). Galileo’s correspondenceis in EN, X–XVIII.

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time. The first case study concerns Galileo’s theory of the strength of materials,and the second his atomistic conception of heat. The third part—The Engineer andthe Scientist—is devoted to the definition of the figure of the engineer-scientist asa historiographical key for investigating further aspects of the interaction betweentheoretical and practical knowledge, on which the early modern scientific revolutionwas based.

First part The profound changes in the art of war that took place from the endof the fifteenth century serve as the historical background for the first part. Thispart comprises three chapters. The first focuses on young Galileo’s early trainingas an artist-engineer in Florence, after he abandoned the university in Pisa. In thesecond chapter, Galileo’s activity running a smithy and as a designer and maker ofinstruments is taken into consideration: first his activity as a designer and producerof military mathematical instruments in Padova between 1592 and 1610 and, sec-ond, as a designer and maker of optical instruments after 1609 and until the end ofhis life. The third chapter approaches the topic of Galileo’s private courses on for-tifications, which included courses on the science of machines, technical drawingtechniques, military architecture, practical astronomy and the use of artillery.

The overarching message of the first part of this work is that Galileo’s activi-ties in the realm of practical knowledge—designer, maker, producer and evaluatorof instruments, and teacher—can be generally interpreted as the typical activitiesof most of those who received training as an artist-engineer at the end of the six-teenth century. Moreover, against the historical background according to whichartist-engineers were expected to address their efforts to meet the particular needsof the art of war, and the fact that only those who did so had the chance to improvetheir social status (Biagioli 1989), the first part of this work is able to show howclosely Galileo followed this traditional path, thus earning a strong reputation as amilitary engineer by 1610, up until the publication of his Sidereus nuncius. The titleof this work—Galileo Engineer—is ultimately the natural output of the results ofthe first part.

Second part The second part of this work—Practice and Science—comprisestwo case studies that are able to show how practical knowledge and theoreti-cal developments are related. The first case is concerned with Galileo’s theoryof the strength of materials, published for the first time in 1638 in the Discorsie dimostrazioni intorno à due nuove scienze (EN, VIII:39–318), though its firstdevelopments are dated to 1592. The second case deals with Galileo’s atomisticconception of heat, and how he exposed it in his Il Saggiatore in 1623 (EN,VI:197–372).

The definition of practical knowledge given above still requires further elabo-ration when considered within the frame of the investigations that focus on therelations between Galileo’s shared practical knowledge and his theoretical devel-opments. There was, in fact, a wide spectrum of possibilities, methods and paths forsharing practical knowledge available to people like Galileo. For example, as shownin the second chapter, Galileo produced with his own hands a good series of lensesfor telescopes. In this case Galileo certainly required direct contact with lens makers

Introduction xix

to learn their craft. He also needed to work himself until he achieved a satisfactoryresult. In this case Galileo shared practical knowledge in that he functioned as anartisan himself. At the end of the second chapter it is also shown how Galileo wasrequested to act as an evaluator of machine proposals, eventually presented in theform of a machine model. In this case Galileo did not act as an artisan because he didnot build anything. What he did was evaluate the potential efficiency of the machine.He analyzed the composition of motions displayed by the arrangement of the differ-ent components of the machine. He then analyzed velocities and times of the singlemotions and of the compound motion connecting the point where the moving forcewas applied to the component of the machine that moved and thus accomplished thework. From the proper historical perspective, machine evaluators of this kind wereneither craftsmen nor machine makers. The latter often did not possess the reflectiveknowledge required to calculate the efficiency of the machine and to express it ina way understandable for those who were not experts on machines. Machine eval-uators were engineers, as in people who possessed a good knowledge of practicalgeometry and arithmetic, as well as the fundamentals of the science of machines andexperience of working with compound machines. Making something with one’s ownhands or evaluating something built or conceived by someone else were two waysfor Galileo to be connected to practical knowledge. Both of them presuppose a pro-cess of sharing practical knowledge, but in two very different forms and with twovery distinct targets.

Following these two different paths of sharing practical knowledge was a naturalconsequence of Galileo’s apprenticeship as an artist-engineer: a person able to workwith his hands and, at the same time, a person who had received enough mathe-matical knowledge and skill to accomplish a more reflective approach to practicalknowledge as well. Galileo came into contact with practical knowledge through bothof these two forms of sharing processes.

The first of the case studies shows how Galileo’s science of the strength ofmaterials is rooted in the knowledge and experience of the Venetian shipwrightsemployed at the Arsenal. In this case Galileo shared the knowledge of shipwrightsnot as a craftsman but as sort of (unsuccessful) evaluator. This case study, more-over, also shows that the theoretical paths which led Galileo through the shipyards,and especially the ones that led him to reframe such practical knowledge within themathematical deductive structure of his theory, was specifically Aristotelian.

A similar result, though with different shadings, is achieved on the basis of theinvestigations directed towards understanding the research paths that led Galileo toformulate his atomistic conception of heat in 1623. In this case Galileo’s researchwas grounded on the practical knowledge he possessed in the field of hydraulics and,specifically, pneumatics. Thanks to such a skill, Galileo was able to be one of thefirst to start working with the thermoscope for scientific purposes. The thermoscopewas a pneumatic instrument applied from the beginning of the seventeenth centuryon to measure temperature, for the first time without recourse to the human senses.According to the results of this research Galileo shared practical knowledge both asa craftsman and as an evaluator. Galileo’s aim to explain the functioning of such an

xx Introduction

instrument, which in modern terms worked on the basis of air’s capacity to contractand expand, led him, moreover, to reconsider his practical knowledge in the light ofAristotelian doctrines, such as the doctrine of the transformation of the elements.

If the first part of this work enables the historian to define Galileo as an engineer,that is, as an artist-engineer, the second part clearly shows how Galileo generatednew scientific knowledge by acting not only as an engineer, but also as an expert onAristotelian natural philosophy.

Third part The last part of this work—The Engineer and the Scientist—is ded-icated to unifying all of the results achieved in the previous ones. To which extentGalileo can be considered as a military engineer and to which extent Galileo wasnot only a military engineer are the main questions the last part aims to answer. Thecontext of Galileo’s activity as a military engineer, the method he followed as anAristotelian engineer in generating new scientific knowledge, and all of the singleresults presented in the previous part, constitute the foundation of a historiographi-cal analysis of the figure of the early modern engineer-scientist, with which the finalpart concludes.

Galileo is identified as belonging to the category of the engineer-scientists, thepivot around which the scientific revolution developed.

Conspicuously, this work does not make use of the word “practitioner” (asidefrom this paragraph). Many recent historical studies that focus on the emergence ofnew scientific knowledge during the early modern period already have pointed to thefact that the early modern scientific revolution is somehow connected to the workof the “practitioners.” However, this term is universally used in a very vague way todenote a plethora of figures ranging from the illiterate young assistant of a machinemaker to the highly educated military engineer at a sixteenth-century court. There isa qualitative difference between these figures, however, especially when the periodstarting from the second half of the sixteenth century is taken into consideration.The difference consists in the fact that engineers and architects, for example, fromthe end of the sixteenth century, already possessed relevant reflective knowledgeconcerned with their practical activities, and this to such an extent that many ofthem had already entered into the scientific discourse of that period.5 Craftsmen andforemen, on the other side, had no such reflective knowledge. While investigatingthe emergence of Galileo’s science, therefore, it does make a difference whetherhe was observing how a lens maker ground his object or whether he was speakingwith a military architect educated, for example, at the Accademia del disegno inFlorence. In conclusion, this work differentiates between craftsmen, who were thosepersons manually involved in practical activities such as, for example, mechanics incharge of assembling machines, and artist-engineers, who, to remain in the field ofactivity devoted to machine building, were in charge of conceiving, designing, andevaluating machines and acted as supervisors of their construction.

5Engineers had already approached theoretical investigations at the end of the sixteenth century,especially in the fields of activity related to hydraulics and pneumatics (Valleriani 2007).

Introduction xxi

How to Read this Book

The book ends with an appendix comprising a selection of letters by and to Galileo.Such correspondence is particularly relevant to evaluate Galileo’s activity as anengineer; although they were published by Antonio Favaro, they have not receivedthe attention they deserve from historians. The appended letters are published inEnglish translation for the first time and quotations from them are marked in italics.The original text of the letters is not reprinted, as for Favaro’s edition of Galileo’sworks is available at many libraries and also accessible via the Internet at severalURLs. Appropriate references and cross-references link the book with the sourcesin translated form.

For the same reason, no original text is given for all of the quotations in Englishtranslation from Galileo’s major works, nor for all easily accessible sources likeAristotle’s major works. In all other cases, the original texts are in the footnotes.

Sources and secondary literature are given in two separate bibliographies.References to Galileo’s works also published in Le opere di Galileo Galilei editedby Antonio Favaro make use of the bibliographic data of the latter and not of thoseof the original publications. These, however, can be found in a distinct bibliographycontaining Galileo’s works that are consulted in this research.

Acknowledgments This book originated as a PhD thesis submitted to the Humboldt Universitätzu Berlin. It was written in Department 1 of the Max Planck Institute for the History of Sciencein Berlin. Detailling the help, support and guidance that Jürgen Renn provided at many differentlevels while producing this work would require a separate chapter. I would like to emphasize herethe crucial role he has played in this research. From May 2005 on, the work was accomplishedin the framework of Project CRC 644: Transformations of Antiquity, funded by the DeutscheForschungsgemeinschaft. The final structure of the book is the consequence of the research andof the exchanges conducted at the Department of History of Science of Harvard University duringa 3-month stay at the beginning of 2009. I would like to thank Giunti Editore, the BibliotecaNazionale Centrale of Florence, the Istituto e Museo di Storia della Scienza of Florence, theBiblioteca Riccardiana also of Florence, and the Staats- und Universitätsbibliothek of Hamburgfor their permission to reproduce the illustrations.

The necessity to systematically investigate practical knowledge as the root of Galileo’s sci-ence emerged during research group meetings of Department I of the Max Planck Institute for theHistory of Science in Berlin between 2000 and 2002. Those meetings, in which I had the honor toparticipate, were largely devoted to the discussion of long-durée visions concerning the history ofmechanics and their conditions of validity, which historians had eventually to prove. Also funda-mental for the emergence of the specific hypothesis concerning Galileo are several works producedagainst the background of the same meetings: Renn (2001), Renn et al. (2001), Renn and Valleriani(2001) and Lefèvre (2001). I would therefore like to acknowledge all of the scholars who attendedthose meetings: Katja Bödecker, Jochen Büttner, Peter Damerow, Marcus Popplow, Jürgen Renn,Simone Rieger, Matthias Schemmel, Markus Schnöpf and Paul Weinig. In particular, I thank PeterDamerow for his accurate and critical reading of the very first version, Marcus Popplow for hisreading of Chapters 2 and 3, and Jochen Büttner for continuous exchanges up to the very last phase.For the construction of the research frame within which the investigations presented in Chapter 5could be undertaken, I would like to thank Lorraine Daston, who kindly advised me in approachingthe history of meteorology. Raymond Fredette and Massimiliano Badino, moreover, both helpedwith their readings of Chapter 4. The research presented in this chapter was also improved by theuseful comments of Antonio Becchi and Gianni Micheli.

xxii Introduction

The preparation of the final version of the book was supported by detailed readings by HorstBredekamp, Sven Dupré, Rivka Feldhay, Paolo Galluzzi, and Wolfgang Lefèvre. Intensive anduseful exchanges have been held as well with Mark Schiefsky, Gideon Freudenthal, AlexanderMarr, David McGee, Peter McLaughlin, Milena Wazeck, Dagmar Schäfer, Matthias Schemmel,Urs Schoepflin, and Ursula Klein. As mentioned, the final structure of the book was developed inconsequence of the discussions and exchanges held at the meetings of the Early Modern WorkingGroup of the Department of History of Science at Harvard University. From this perspective I amparticularly indebted to Mario Biagioli, whose comments were decisive during the preparation ofthe last version. Ralf Hinrichsen, Tom Werner and Christian Voller helped to revise the bibliogra-phy. Oona Leganovic performed a style-sheet check. Susan Richter helped instrumentally in givingfluency to the text. Petra Schröter and Shadiye Leather-Barrow were particularly helpful in accom-plishing many administrative tasks, especially during the PhD phase, and later Monika Liedtke aswell. Sabine Bertram helped to obtain electronic reproductions of the illustrations and the relatedpermissions. Lindy Divarci provided fundamental assistance at each step of this research, so thatit is no exaggeration to state that without her it is doubtful that this book would have ever beencompleted. On the publishing end, I would like to thank Lucy Fleet, whose professionality andfriendliness propelled me through the publishing process. Since this is my first monograph, I alsowould like to thank, finally, Alberto Artosi, now Professor for Theory of Law and Legal Logic andformerly Professor for Philosophy of Science at the University of Bologna. He helped me to realizemy passion for research and gave me the solid basis on which I could begin such an intellectualadventure.

I dedicate this work to my wife Ulrike and to my sons Dante and Zeno.

Dahlem, October 9, 2009