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Home , Galileo Galilei, Two New Sciences

GALILEO BOSTON STUDIES IN THE PHILOSOPHY OF

VOLUME 269

Editors

ROBERT S. COHEN, Boston JÜRGEN RENN, Max Institute for the KOSTAS GAVROGLU, University of Athens

Editorial Advisory Board

THOMAS F. GLICK, Boston University ADOLF GRÜNBAUM, University of Pittsburgh SYLVAN S. SCHWEBER, Brandeis University JOHN J. STACHEL, Boston University MARX W. WARTOFSKY†, (Editor 1960–1997)

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

by MATTEO VALLERIANI Max Planck Institute for the History of Science Berlin, Germany

123 Matteo Valleriani Max Planck Institute for the History of Science Boltzmannstr. 22 14195 Berlin Germany [email protected]

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

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

Library of Congress Control : 2010922899

© Springer Science+Business Media B.V. 2010 No part of this may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, microfilming, recording or otherwise, without written permission from the Publisher, with the exception of any material supplied specifically for the purpose of being entered and executed on a computer system, for exclusive use by the purchaser of the work.

Printed on acid-free paper

Springer is part of Springer Science+Business Media (www.springer.com) Carlo de Bonardis (17th century). undertaking an . Oil painting (Bona Castellotti, Gamba et al. 1999/2000, 141)

Contents

Foreword: The Historical of ...... xi Jürgen Renn Introduction ...... xv

Part I War and Practice 1 Artist-’ Apprenticeship and Galileo ...... 3 The Political and Economic Context ...... 3 The Education of Artist-Engineers ...... 7 Galileo’sApprenticeship...... 12 FromtheApprenticeshiptotheWorkshopviatheUniversity...... 15 TheBuzzoftheWorkshop...... 19 2 Instruments and ...... 21 Galileo’s Balance Sheet ...... 24 The Production and Organization of the Workshop ...... 26 The Military Compass ...... 27 The Reduction Compass ...... 38 TheSurveyingCompass...... 39 OtherInstrumentsandTools...... 41 Lenses...... 41 Glass Production ...... 48 Adapting the for other Optical Devices ...... 53 Mirrors...... 60 for Pounding ...... 66 Machine for Lifting Heavy ...... 67 Water Lifting Machine ...... 68 Galileo as a Military Engineer ...... 69 3 Galileo’s Private Course on Fortifications ...... 71 TheStructureoftheBusiness...... 72 for the Military Art ...... 75 Military Architecture ...... 77 Powered by Gunpowder ...... 86

vii viii Contents

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

Part II Practice and Science 4 The Knowledge of the ...... 117 Dating Galileo’s Work on the Science of Materials ...... 120 The Key Question of the Machine Makers ...... 120 Galileo’s Cantilever Model ...... 122 The Origins of the Engineers’ Cantilever Model ...... 124 Galileo at the Arsenal: The Aristotelian Nautical Questions ...... 132 Did the Venetian Arsenal Employ Galileo? ...... 138 Galileo’s Apprenticeship as a Proto ...... 140 Galileo’s Masterpiece: The Oar Model ...... 150 Did Galileo Become a Proto?...... 152 5 Pneumatics, the and the New Atomistic Conception of Heat ...... 155 The Thermoscope ...... 158 The Emergence of the Thermoscope ...... 160 From the Thermoscope to the ...... 165 Empirical Data Provided by the Thermoscope ...... 169 The Reception of Ancient Pneumatics ...... 172 Galileo as a Pneumatic Engineer ...... 178 The Functioning of the Thermoscope ...... 181 Galileo’sDoctrineofHeat...... 186 The Generation of a Heat Doctrine ...... 190

Part III The Engineer and the Scientist 6 Was Galileo an Engineer? ...... 193 RevolutionoftheArtofWar...... 193 Galilei in the Current of Warfare ...... 197 Beyond ...... 199 The Aristotelian Engineer ...... 203 Generation of Knowledge ...... 206 Engineer- ...... 207 Sources: Galileo’s Correspondence ...... 213 NotesontheTranslations...... 213 Galileo to G. Contarini in . Padova, March 22, 1593 ...... 214 G. Contarini to Galileo in Padova. Venice, March 28, 1593 ...... 216 Galileo to A. Mocenigo in Venice. Padova, January 11, 1594 ...... 219 G. Sagredo to Galileo in Padova. Venice, January 17, 1602 ...... 221 Contents ix

G. Sagredo to Galileo in Padova. Venice, August 23, 1602 ...... 222 Galileo to A. de’ Medici in . Padova, February 11, 1609 .... 223 G. Bartoli to B. Vinta in Florence. Venice, September 26, 1609 . .... 225 M. Hastal to Galileo in Florence. Prague, August 24, 1610 ...... 226 D. Antonini to Galileo in Florence. Brussels, February 4, 1612 . .... 227 G. Sagredo to Galileo in Florence. Venice, June 30, 1612 ...... 229 G. Sagredo to Galileo in Florence. Venice, May 9, 1613 ...... 231 G. Sagredo to Galileo in Florence. Venice, July 27, 1613 ...... 233 G. Sagredo to Galileo in Florence. Venice, August 24, 1613 ...... 234 G. B. Baliani to Galileo in Florence. Genoa, April 4, 1614 ...... 238 G. F. Sagredo to Galileo in Florence. Venice, February 7, 1615 . .... 239 G. F. Sagredo to Galileo in Florence. Venice, March 15, 1615 ...... 241 G. F. Sagredo to Galileo in Florence. Venice, April 11, 1615 ...... 244 B. Castelli to Galileo in Florence. , May 24, 1617 ...... 248 Galileo to Leopold of Austria in Innsbruck. Florence, May 23, 1618 . . 250 G. F. Sagredo to Galileo in Florence. Morocco, August 4, 1618 . .... 252 G. F. Sagredo to Galileo in Florence. Venice, August 18, 1618 . .... 255 G. F. Sagredo to Galileo in Bellosguardo. Venice, October 27, 1618 . . 256 G. F. Sagredo to Galileo in Florence. Venice, November 3, 1618 .... 257 G. F. Sagredo to Galileo in Florence. Venice, December 22, 1618 .... 259 G. F. Sagredo to Galileo in Bellosguardo. Venice, March 30, 1619 . . . 260 G. C. Lagalla to Galileo in Florence. Rome, July 30, 1621 ...... 263 G. B. Guazzaroni to Galileo in Aquasparta. Todi, April 20, 1624 .... 264 Galileo to F. Cesi in Rome. Bellosguardo, September 23, 1624 . .... 266 G. di Guevara to Galileo in Florence. Teano, November 15, 1627 .... 268 A. Arrighetti to Galileo in . Florence, September 25, 1633 . .... 270 Galileo to A. Arrighetti in Florence. Siena, September 27, 1633 . .... 273 N. Aggiunti to Galileo in Florence. Pisa, February 22, 1634 ...... 274 F. Micanzio to Galileo in Florence. Venice, July 8, 1634 ...... 276 A. de Ville to Galileo in Arcetri. Venice, March 3, 1635 ...... 277 F. Micanzio to Galileo in Florence. Venice, December 1, 1635 . .... 284 B. Cavalieri to Galileo in Arcetri. Bologna, March 11, 1636 ...... 285 Galileo to L. Reael in . Arcetri, June 5, 1637 ...... 288 Galileo to F. Micanzio in Venice. Arcetri, November 20, 1637 ...... 295 Credits ...... 297 References ...... 299 Galileo’sWorks...... 299 PrimaryLiterature...... 301 Secondary Literature ...... 306 Name Index ...... 315 Illustration Index ...... 319

Foreword: The Historical Epistemology of Mechanics

Jürgen Renn

The historical epistemology of mechanics studies the long-term development of mechanical knowledge. Mechanical knowledge concerns material bodies in and , their , and the that cause or resist such motions. Mechanical knowledge enables us to predict how bodies change their position with time as long as we know their current state and the forces acting upon them. Mechanical knowledge of this kind played a special role in the process of transformation from to modern science. Natural philos- ophy from its very inception in the works of constructed conceptual systems to represent pictures of as a whole. But, in contrast to such global intentions, the origins of mechanical knowledge have to be sought in the much more down-to-earth practical activities of achieving the specific tasks of everyday life. Over a long historical period, the development of mechanical knowledge and its transmission from one generation to the next remained an inherent dimension of such activities, unrelated to any cognitive endeavors aimed at constructing a mechanical worldview. It was only after the first attempts in classical antiquity to include mechanical knowledge in the conceptual systems of natural philoso- phy that its assimilation to them and the corresponding accommodation of such systems to mechanical concepts led to conflicts between mechanical knowledge and knowledge about as a whole. It was only after the growing body of mechanical knowledge became a vital resource of early modern societies that mechanical knowledge within its own conceptual systematization started to compete with natural philosophy by constructing its own worldviews. This finally resulted in early modern in what has been called the “mechanization of the world picture.” The main goal of the series under the heading The Historical Epistemology of Mechanics, conceived in analogy to the four-volume set on The Genesis of General Relativity, is to explain the development and diffusion of mechanical knowledge in terms of historical-epistemological concepts. The studies presented within the series are based on a research project centered at the Max Planck Institute for the History of Science in Berlin. While the emphasis of the research has been on the period of the Scientific Revolution, the also takes into account the long-term

xi xii Foreword: The Historical Epistemology of Mechanics development of mechanical knowledge without which neither its emergence nor the consequences of this period can be adequately understood. Just as the reconstruction of the relativity revolution in The Genesis of General Relativity takes Einstein’s work as the point of reference for a thorough contextualization of his achieve- ments, the reconstruction of the transformation of mechanical knowledge during the Scientific Revolution similarly refers to Galileo’s work as a point of departure for outlining a historical epistemology of mechanics. The development of an adequate theoretical framework provides a common basis for the investigations constituting The Historical Epistemology of Mechanics.The longevity of mechanics makes it particularly clear that large domains of human knowledge accumulated by experience are not simply lost when theories are revised, even if this knowledge does not explicitly appear in such theories. Thus formal 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 of the transmission of mechanical knowledge to be accounted for. In order to explain structural transformations of systems of knowledge, it is furthermore necessary to take into account the collective character and the historical specificity of the knowledge being transmitted and transformed, as well as to employ sophisticated models for reconstructing processes of knowledge development. Concepts such as “mental model”, “shared knowledge”, “challenging object”, and “knowledge reorganization” have turned out in our work to be pivotal for such explanations. We conceive of mental models as knowledge representation structures based on default logic, which allow inferences to be drawn from prior experiences about complex objects and processes even when only incomplete information on them is available. 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. They are, in any case, characterized by a remarkable longevity—even across historical breaks—as becomes clear when considering examples such as the mental models of an atom, of a balance, of the center of , or of positional . Their persistence in shaping the shared knowledge documented by the historical sources becomes particularly apparent in the consistency of the terminology used, a consis- tency that offers one important element for an empirical control in the reconstruction of mental models and their historical development. The concept of mental model is particularly suited to study the role of practical knowledge for the transformation of mechanics in the . 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 for them. Examples run from mechanical devices challenging Aristotelian , via artillery challenging early modern theories of , to black body radiation challenging classical radiation theory. In reaction to such challenges, knowledge systems are typically further elaborated, occasionally to the extent that they give rise to internal tensions and even inconsistencies. Such explorations of their limits may then 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. Such processes of reorganization may be exemplified by the emergence of theoretical mechanics from Aristotelian natural philosophy in ancient Greece, the transforma- tion of preclassical into in early modern times, or the emergence of quantum theory from classical at the turn of the last century. The investigations constituting The Historical Epistemology of Mechanics build on this theoretical framework, centering on the role of shared knowledge, of challenging objects, and of knowledge reorganization. The first study, Matthias Schemmel’s The English Galileo: ’s Work on Motion as an Example of Preclassical Mechanics, has investigated the shared knowledge of preclassical mechanics by relating the work of Thomas Harriot on motion, documented by a wealth of manuscripts, to that of Galileo and other contemporaries. While the paths Harriot traces through the shared knowledgeare different from Galileo’s, the work of the two scientists displays striking similarities as regards their achievements as well as the problems they were unable to solve. The study of Harriot’s parallel work has thus allowed the exploration of the structure of the shared knowledge of early mod- ern mechanics, to perceive possible alternative histories, and to distinguish between individual peculiarities and shared structures of early modern mechanical reasoning. This volume, Galileo Engineer, the second study of the series, looks more closely at the role of Galileo as a practical mathematician and engineer-scientist. It focuses on his intellectual development in the frame of the interaction between natural philosophy and the challenging objects provided by technological developments. It analyzes Galileo’s contribution to the practical science of machines as well as his role as a teacher involved in the contemporary art of war. The results of this analysis highlight Galileo’s profile as a military engineer. By means of two case studies this book develops a model according to which new scientific knowledge was generated on the basis of the interaction between theoretical knowledge—basically Aristotelian—and the practical knowledge Galileo shared with his contemporaries. The first case study concerns Galileo’s theory of the strength of materials, namely the first of his Two New , and its relation to the practical knowledge of the Venetian Arsenal. The second case study concerns the emergence of Galileo’s heat doctrine on the basis of the practical knowledge related to pneumatics. Galileo’s work 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 look more closely at the reorgani- zation of mechanical knowledge that took place in the course of Galileo’s research process stimulated by contemporary challenging objects. A further study will artic- ulate more extensively the theoretical foundations of a historical epistemology of mechanics, providing an outline of the long-term development of mechanical knowl- edge. The theoretical framework adopted makes it possible to analyze and make explicit the relations between diverse forms of mechanical knowledge which have hitherto been mostly treated in isolation from each other. Among these differ- ent forms is the intuitive knowledge gained through basic material activities, the practical knowledge of professionals, and the theoretical knowledge resulting from xiv Foreword: The Historical Epistemology of Mechanics 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 of mechanical knowledge from its anthropological origins via the formation of a mechanical world view to the understanding of material interactions within the framework of quantum mechanics and of the space-time geometry of modern physics. Introduction

Galileo Galilei (1564–1642), his life and his work have been and continue to be 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 : Galileo the great theoretician, Galileo the keen , Galileo the genius, Galileo the , Galileo the mathematician, Galileo the solitary thinker, Galileo the founder of modern science, Galileo the heretic, Galileo the courtier, Galileo the early modern , Galileo the Aristotelian, Galileo the founder of the Italian scientific language, Galileo the cosmologist, Galileo the Platonist, Galileo the artist and Galileo the democratic scientist. These may be only a few of the identities that historians of science have associated with Galileo. And now: Galileo the engineer! That Galileo had so many faces, or even identities, seems hardly plausible. But by focusing on his activities as an engineer, historians are able to reassemble Galileo in a single persona, at least as far as his scientific work is concerned. The impression that Galileo was an ingenious and isolated theoretician derives from his scientific work being regarded outside the context in which it originated. Thanks to a series of historical research works dedicated to case studies and to a certain historiographical tradition that began in the 1920s, represented chiefly by Leonardo Olschki (Olschki 1919–1927), 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 in his scientific speculations. A relevant case study that confirms such an inference concerns 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 connected to the knowledge of early modern artillerists (Renn et al. 2001), and thus that the main 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 how relevant aspects of Galileo’s , 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 the most suitable guide for contextualizing his theoretical speculations. In consequence of these considerations the emerged that Galileo’s science, in general, is

xv xvi Introduction rooted in the practical knowledge of his time.1 Accordingly Pamela Smith argued in favor of a conception of new early modern science as first “disseminated and inculcated” 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 active in its framework are needed. This work makes use of a definition of artist-engineer formulated 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 basis of his analysis of the training of famous engineers, architects and artists. He found similarities in the training curricula for these professions and formulated the the- sis that an artist, engineer or architect became such after an apprenticeship, based on the work he was commissioned to perform, and on his success in completing a project that embraced either engineering, architecture or art. Zilsel’s thesis con- tributes to clarifying the tendency in Renaissance culture not to consider these as separate fields of activity, and therefore forces the contemporary historian to turn to a later period to seek and understand, for example, the process that led to a view of the artist as apparently and completely removed from the technological development of his era.3 One relevant of the early modern period, and especially of Galileo’s time, was the huge increase in textual output as result of a process of codify- ing practical knowledge. These texts mostly contained the knowledge of military engineers and architects, machine makers, makers of mathematical instruments and shipwrights. The texts, together with manuscripts and books on subjects such as theatrical machinery, trick fountains, automata, metallurgy, instruments, mechani- cal tools, and practical optics, constitute a considerable portion of the entire textual production of the age. The knowledge codified in these writings, together with the knowledge integrated directly into the results of their practical implementation, such as cathedrals, milling devices, galleys, tools and instruments, many of which were left behind by those who never wrote a , constitutes this work’s definition of practical knowledge. Until now no systematic research has ever been undertaken that aims to show how Galileo’s interactions with the practical knowledge of his time were more or less intensive and fruitful by taking the entire spectrum of his practical activities into consideration rather than just a selection. This work aspires to present such a panoramic view. In accomplishing this goal, however, the level of generaliza- tion implied in the leading hypothesis had to be abandoned. This work follows Galileo through the main phases of his life—his time in Florence, in Pisa, in Padova and his subsequent return to Florence, but it is also organized thematically in

1Thomas Kuhn also formulated such an encompassing hypothesis. However, he did not investigate the 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). Introduction xvii accordance with the specific activities Galileo undertook. According to this plan- ning, the space-time area on which this research focuses narrows to the Italian peninsula in the period that includes the second half of the sixteenth and the first half of the seventeenth centuries. Each of the practical activities undertaken by Galileo and all of the aspects of practical knowledge shared by Galileo are analyzed starting from historical evidence such as Galileo’s personal and administrative documents. His correspondence, as collected and published by Antonio Favaro,4 plays a major role. The lives and works of relevant correspondents and, in particular, their relations with Galileo, are then considered on the basis of the leading hypothesis of this work. Concerning the subjects discussed, the state of the specific practical knowledge involved is investi- gated in greater detail, mainly by means of compiled by experts in various practical activities, as contemporary to Galileo as possible. A comparison between Galileo’s arguments and those of such experts, to the extent that these can be inferred from their treatises and material works, reveals the intensity of Galileo’s practical activity in each of the fields in which he was involved, and finally the “degree” to which he utilized the practical knowledge of his day. This analysis is performed for each kind of practical activity undertaken by Galileo. Galileo’s major published works, finally, are related to those activities as well. Thus, the traditional historical approach to Galileo, which begins with his major publications, is reversed. All of the letters which play a decisive role in this work have therefore been appended in the author’s English translation. According to this method, the work turns out to have two main protagonists: the first is Galileo, while the other is practical knowledge, or rather those who embodied and implemented it. Although the principal aim of this book is to approach Galileo’s work from the perspective of the practical knowledge, Galileo himself can be used as 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 the seventeenth 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 to show how Galileo followed the typical educational path of the artist-engineer in the second half of the sixteenth century and, finally, how he consequently began his career and retained the profile of a military engineer. The second part—Practice and Science—comprises two major case studies that are able to show how particular theoretical 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 Favaro edited Le opere di 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 the present work and quoted with the abbreviation EN (Edizione Nazionale). Galileo’s correspondence is in EN, X–XVIII. xviii Introduction 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 and the Scientist—is devoted to the definition of the figure of the engineer-scientist as a historiographical key for investigating further aspects of the interaction between theoretical and practical knowledge, on which the early modern scientific revolution was based. First part The profound changes in the art of war that took place from the end of the fifteenth century serve as the historical background for the first part. This part comprises three chapters. The first focuses on young Galileo’s early training as an artist-engineer in Florence, after he abandoned the university in Pisa. In the second chapter, Galileo’s activity running a smithy and as a designer and maker of instruments is taken into consideration: first his activity as a designer and producer of 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 of his life. The third chapter approaches the topic of Galileo’s private courses on for- tifications, which included courses on the science of machines, technical drawing techniques, military architecture, practical 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 evaluator of instruments, and teacher—can be generally interpreted as the typical activities of 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 which artist-engineers were expected to address their efforts to meet the particular needs of the art of war, and the that only those who did so had the chance to improve their social status (Biagioli 1989), the first part of this work is able to show how closely Galileo followed this traditional path, thus earning a strong reputation as a military engineer by 1610, up until the publication of his . The title of this work—Galileo Engineer—is ultimately the natural output of the results of the first part. Second part The second part of this work—Practice and Science—comprises two case studies that are able to show how practical knowledge and theoreti- cal developments are related. The first case is concerned with Galileo’s theory of the strength of materials, published for the first time in 1638 in the Discorsi e dimostrazioni intorno à due nuove scienze (EN, VIII:39–318), though its first developments are dated to 1592. The second case deals with Galileo’s atomistic conception 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 the relations between Galileo’s shared practical knowledge and his theoretical devel- opments. There was, in fact, a wide spectrum of possibilities, methods and paths for sharing practical knowledge available to people like Galileo. For example, as shown in the second chapter, Galileo produced with his own hands a good series of lenses for . 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 satisfactory result. In this case Galileo shared practical knowledge in that he functioned as an artisan himself. At the end of the second chapter it is also shown how Galileo was requested to act as an evaluator of machine proposals, eventually presented in the form of a machine model. In this case Galileo did not act as an artisan because he did not 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 and times of the single motions and of the compound motion connecting the point where the moving force was applied to the component of the machine that moved and thus accomplished the work. From the proper historical perspective, machine evaluators of this kind were neither craftsmen nor machine makers. The latter often did not possess the reflective knowledge required to calculate the efficiency of the machine and to express it in a way understandable for those who were not experts on machines. Machine eval- uators were engineers, as in people who possessed a good knowledge of practical geometry and arithmetic, as well as the fundamentals of the science of machines and experience of working with compound machines. Making something with one’s own hands or evaluating something built or conceived by someone else were two ways for 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 two very distinct targets. Following these two different paths of sharing practical knowledge was a natural consequence of Galileo’s apprenticeship as an artist-engineer: a person able to work with 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 practical knowledge as well. Galileo came into contact with practical knowledge through both of these two forms of sharing processes. The first of the case studies shows how Galileo’s science of the strength of materials is rooted in the knowledge and experience of the Venetian shipwrights employed at the Arsenal. In this case Galileo shared the knowledge of shipwrights not 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 the mathematical deductive structure of his theory, was specifically Aristotelian. A similar result, though with different shadings, is achieved on the basis of the investigations directed towards understanding the research paths that led Galileo to formulate his atomistic conception of heat in 1623. In this case Galileo’s research was grounded on the practical knowledge he possessed in the field of and, specifically, pneumatics. Thanks to such a skill, Galileo was able to be one of the first to start working with the thermoscope for scientific purposes. The thermoscope was a pneumatic instrument applied from the beginning of the seventeenth century on to measure , for the first time without recourse to the human senses. According to the results of this research Galileo shared practical knowledge both as a 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 contract and expand, led him, moreover, to reconsider his practical knowledge in the of Aristotelian 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 generated new scientific knowledge by acting not only as an engineer, but also as an expert on Aristotelian 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 extent Galileo can be considered as a military engineer and to which extent Galileo was not only a military engineer are the main questions the last part aims to answer. The context of Galileo’s activity as a military engineer, the method he followed as an Aristotelian engineer in generating new scientific knowledge, and all of the single results 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 final part concludes. Galileo is identified as belonging to the category of the engineer-scientists, the pivot around which the scientific revolution developed. Conspicuously, this work does not make use of the word “practitioner” (aside from this paragraph). Many recent historical studies that focus on the emergence of new scientific knowledge during the early modern period already have pointed to the fact that the early modern scientific revolution is somehow connected to the work of the “practitioners.” However, this term is universally used in a very vague way to denote a plethora of figures ranging from the illiterate young assistant of a machine maker to the highly educated military engineer at a sixteenth-century court. There is a qualitative difference between these figures, however, especially when the period starting from the second half of the sixteenth century is taken into consideration. The difference consists in the fact that engineers and architects, for example, from the end of the sixteenth century, already possessed relevant reflective knowledge concerned with their practical activities, and this to such an extent that many of them had already entered into the scientific discourse of that period.5 Craftsmen and foremen, on the other side, had no such reflective knowledge. While investigating the emergence of Galileo’s science, therefore, it does make a difference whether he was observing how a lens maker ground his object or whether he was speaking with a military architect educated, for example, at the Accademia del disegno in Florence. In conclusion, this work differentiates between craftsmen, who were those persons manually involved in practical activities such as, for example, mechanics in charge of assembling machines, and artist-engineers, who, to remain in the field of activity devoted to machine building, were in charge of conceiving, designing, and evaluating 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 an engineer; although they were published by Antonio Favaro, they have not received the attention they deserve from historians. The appended letters are published in English 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’s works is available at many libraries and also accessible via the Internet at several URLs. Appropriate references and cross-references link the book with the sources in translated form. For the same reason, no original text is given for all of the quotations in English translation from Galileo’s major works, nor for all easily accessible sources like Aristotle’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 edited by Antonio Favaro make use of the bibliographic data of the latter and not of those of the original publications. These, however, can be found in a distinct bibliography containing Galileo’s works that are consulted in this research. Acknowledgments This book originated as a PhD thesis submitted to the Humboldt Universität zu Berlin. It was written in Department 1 of the Max Planck Institute for the History of Science in Berlin. Detailling the help, support and guidance that Jürgen Renn provided at many different levels while producing this work would require a separate chapter. I would like to emphasize here the crucial role he has played in this research. From May 2005 on, the work was accomplished in the framework of Project CRC 644: Transformations of Antiquity, funded by the Deutsche Forschungsgemeinschaft. The final structure of the book is the consequence of the research and of the exchanges conducted at the Department of History of Science of Harvard University during a 3-month stay at the beginning of 2009. I would like to thank Giunti Editore, the Biblioteca Nazionale Centrale of Florence, the Istituto e Museo di Storia della Scienza of Florence, the Biblioteca Riccardiana also of Florence, and the Staats- und Universitätsbibliothek of Hamburg for 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 the History of Science in Berlin between 2000 and 2002. Those meetings, in which I had the honor to participate, were largely devoted to the discussion of long-durée visions concerning the history of mechanics 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 produced against 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 attended those meetings: Katja Bödecker, Jochen Büttner, Peter Damerow, Marcus Popplow, Jürgen Renn, Simone Rieger, Matthias Schemmel, Markus Schnöpf and Paul Weinig. In particular, I thank Peter Damerow for his accurate and critical reading of the very first version, Marcus Popplow for his reading 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 5 could be undertaken, I would like to thank Lorraine Daston, who kindly advised me in approaching the history of . Raymond Fredette and Massimiliano Badino, moreover, both helped with their readings of Chapter 4. The research presented in this chapter was also improved by the useful comments of Antonio Becchi and Gianni Micheli. xxii Introduction

The preparation of the final version of the book was supported by detailed readings by , Sven Dupré, Rivka Feldhay, Paolo Galluzzi, and Wolfgang Lefèvre. Intensive and useful exchanges have been held as well with Mark Schiefsky, Gideon Freudenthal, Alexander Marr, 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 in consequence of the discussions and exchanges held at the meetings of the Early Modern Working Group of the Department of History of Science at Harvard University. From this perspective I am particularly indebted to Mario Biagioli, whose comments were decisive during the preparation of the 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 giving fluency 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 as well. Sabine Bertram helped to obtain electronic reproductions of the illustrations and the related permissions. Lindy Divarci provided fundamental assistance at each step of this research, so that it is no exaggeration to state that without her it is doubtful that this book would have ever been completed. On the publishing end, I would like to thank Lucy Fleet, whose professionality and friendliness propelled me through the publishing process. Since this is my first monograph, I also would like to thank, finally, Alberto Artosi, now Professor for Theory of Law and Legal Logic and formerly Professor for at the University of Bologna. He helped me to realize my passion for research and gave me the solid basis on which I could begin such an intellectual adventure. I dedicate this work to my wife Ulrike and to my sons Dante and Zeno.

Dahlem, October 9, 2009