Europe and the Microscope in the Enlightenment

Thesis

Reference

Europe and the Microscope in the Enlightenment

RATCLIFF, Marc

Abstract

While historians of the microscope currently consider that no programme of microscopy took place during the Enlightenment, the thesis challenges this view and aims at showing when and where microscopes were used as research tools. The focus of the inquiry is the research on microscopic animalcules and the relationship of European microscope making and practices of microscopy with topical trends of the industrial revolution, such as quantification.

Three waves of research are characterised for the research on animalcules in the Enlightenment: 1. seventeenth-century observations on animalcules crowned by Louis Joblot's 1718 works in the milieu of Paris Académie royale des sciences, 2. mid eighteenth-century observations and experiments on polyps and animalcules (Trembley, Baker and Hill) and, 3. between 1760 and 1790, OF Müller's establishment of the systematics of infusoria in Denmark and Germany.

RATCLIFF, Marc. Europe and the Microscope in the Enlightenment. Thèse de doctorat : UCL

Available at:

http://archive-ouverte.unige.ch/unige:104705

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EUROPE AND THE MICROSCOPE IN THE ENLIGHTENMENT (Full version)

by

Marc James Ratcliff History of Medicine Department of Anatomy University College London

Thesis submitted to University College London for the degree of Doctor of Philosophy

January 2001

Acknowledgments

The writing of this work has benefited from the help of several colleagues at the various Institutes in which I was a pilgrim during three years. The Max Planck Institute für Wissenschaftsgeschichte in Berlin, the Wellcome Institute for the History of

Medicine, and the Institut Louis Jeantet pour l'Histoire de la Médecine in Geneva, provided hospitality between 1997 and 2000. I'm indebted to the directors and professors in these institutes, Professor Lorraine Daston and Hans-Jörg Rheinberger, Professor Bill Bynum and Professor Bernardino Fantini.

I'm particularly indebted to Professor Fantini for his impulse, without whom my work would probably have not been undertaken. I appreciated the constant support of my supervisors Professor Bill Bynum and Janet Browne whose helpful discussions allowed, among other things, suitable revisions in my interpretations. It is also a pleasure to acknowledge the many persons who have assisted at certain stages of research and writing: Giulio Barsanti, Marino Buscaglia, Evelyn Fox-Keller, Alexandre Métraux, Maria-Teresa Monti, Teresa Huguet-Termes were a source of encouragement and ideas.

Eric Ratcliff and Allison Morehead helped greatly to transform my poor English into acceptable reading matter

Without the assistance of a grant n° 8210-050423, from the Fonds National Suisse de la Recherche Scientifique, this research could not have been undertaken. I am grateful to the Royal Society, the Archives de l'Académie des Sciences de Paris, the Bibliothèque Publique et Universitaire in Geneva, and Mr. Jacques Trembley in Geneva for allowing me to quote from manuscript sources in their collections.

Finally, I owe a debt of gratitude beyond calculation to my wife and family.

Warning

Due to the poor quality of the xerox of the figures of eighteenth-century engravings, I redrew slightly certain figures anew in order to get them closer to the original.

Current Abbreviations Used in the Footnotes

BPU Bibliothèque Publique et Universitaire de Genève

CRT Trembley, Maurice & Guyénot, Emile. (Ed.) 1943. Correspondance inédite entre Réaumur et Abraham Trembley, Genève, Georg.

C&C Clay, Reginald S. & Court, Thomas H. 1932. The History of the Microscope Compiled from Original Instruments and Documents, Up to the Introduction of the Achromatic Microscope, London, Griffin. (Reprint London, Holland Press, 1975).

M&R Mazzolini, Renato G. & Roe, Shirley. (Ed.) 1986. Science against the Unbelievers The Correspondence of Bonnet and Needham 1760-1780, Oxford, Voltaire Foundation.

PV AS Procès-verbaux de l’Académie des Sciences.

S&S Shapin, Steven & Schaffer, Simon. 1985. Leviathan and the Air-Pump, Hobbes, Boyle, and the Experimental Life, Princeton, Princeton University Press.

Contents

CHAP 1. INTRODUCTION

1.1. The history of the microscope and its contribution to the history of eighteenth century microscopy.

1.2. Microscopy and the tradition of history of “biological” knowledge 1.2.1. The question of the microscopic illusion

1.2.1. Generation and infusoria

1.3. Modern history and social constructivism

PART 1.THE DEFINITION OF GOOD MICROSCOPICAL OBJECTS 1700-1735

CHAP 2. THE STUDY OF INFUSORIA IN THE FRENCH CONTEXT AT THE TURN OF THE EIGHTEENTH CENTURY

2.1. Louis Joblot and disproving spontaneous generation of infusorians 2.2. Reception of Joblot's work and the academic context

2.3. Reasons for an apparent lack of reception CHAP 3. INSECTS, AMBIGUITY AND HERMAPHRODITISM

3.1. Insects as suitable objects for the microscope

3.2. Cochenille, Kermes and Coccus between ambiguous organisms and hermaphrodites

3.3. The microscope in the arena of the court 3.4. A genealogy for the greenfly

CHAP.4.PRODUCTION AND VISIBILITY OF MICROSCOPES IN THE FIRST HALF OF THE CENTURY.

4.1. Changes in visibility in the European market of microscopy.

4.2. New models and styles in producing microscopes 4.3. From change of shape to changes in production

4.4 Henry Baker and new strategy for an emerging market

4.5. Social and economic cultures of the microscope: Two styles of producing microscopes, in France and Italy

PART 2.THE BREAK WITH THE PAST 1738-1760

CHAP.5. ABRAHAM TREMBLEY, THE POLYP AND NEW DIRECTIONS FOR MICROSCOPICAL RESEARCH

5.1. A model for scientific communication, the European spreading of the polyp and the “democratic microscope”

5.2. Trembley’s effect on microscopy

5.3. A microscopical under water world revealed: from the polyp to marine zoology CHAP.6.THE DISPUTES OVER AUTHORITY AND MICROSCOPICAL OBSERVATIONS

6.1. Preexistence of germ as an Enlightenment’s symbol.

6.2. Breaking the ice: Renewal of spontaneous generation and spirit of system 6.3. From changes of idea to changes in style of communication

6.4. A new impulse for research: Approval and contestation of spontaneism throughout Europe

PART 3.QUANTIFICATION AND INFUSORIA: THE TRUE MICROSCOPICAL OBJECTS, 1760S-1786

CHAP.7.THE QUANTIFYING SPIRIT IN MICROSCOPY AND KEEPING UP WITH MICROSCOPICAL OBJECTS

7.1. Iconographic techniques of microscopy: naturalizing images and an initial approach to quantification

7.2. From minute mensuration to standards of measure 7.3. Quantification of power, magnification and natural size

7.4. The quest for instrumental precision: Micrometers and instruments of division CHAP.8. THE EMERGENCE OF THE SYSTEMATICS OF INFUSORIANS

8.1. The competition in Britain between Hill and Baker for control of microscopy 8.2. The rise of microscopical research in Germany

8.3. Roots for the systematics of microscopic animals 8.4. Establishing the systematics of infusoria

8.4.1. Müller’s 1773 Vermium terrestrium et fluviatilium

8.4.2. The spreading of infusoria and microscopical research in Germany 8.4.3. The definitive foundation: Müller’s 1786 Animalcula infusoria 8.5. Impact of the systematics of infusoria

CHAP.9.INVENTION AND DECONSTRUCTION OF A MYTHOLOGY: THE HISTORY OF MICROSCOPY.

9.1. Anachronism in the history of microscopy 9.2. The invention of the “technological thesis”

9.3. Losing memories

9.4. The functions of the historical reconstruction 9.5. Fetishes, myth of creation and murder of father CHAP.10.CONCLUSION

10.1. Shaping the practices of the microscope

10.2. Historicist categories: systems of practices and microscopical report 10.3. Toward a restitutive history

CHAPTER 1.INTRODUCTION

The aim of this work is to present the history of the multiple uses of the microscope and of microscopic organisms in Europe during the Age of Enlightenment. In contrast to other fields in the history of natural sciences, and to other periods covered by the history of microscopy, this type of historical inquiry was not undertaken, due to several reasons. Indeed, many historical comprehensive works develop topics such as natural history, botany, physiology, animal generation and experimental science of the eighteenth-century. As well, an important amount of research covers seventeenth- century microscopy. But looking for eighteenth-century historiographical case studies in microscopy is a much more fruitless task than searching out eighteenth-century microscopes... Most likely such a situation is not fate, but, as we will see, the product of a historical construction.

If a historiographical tradition refers to a cumulative amount of studies that quote each other, the aim of which is to address specific issues, two main traditions are to be distinguished here. The first and perhaps the better-defined of them is the British --and partly Dutch-- tradition of the history of the microscope. Its founding studies begun to be issued during the second part of the nineteenth-century, and have mostly been carried on by biologists belonging to scientific microscopical societies.¹ The second tradition, focusing on the conceptual and historical aspects of the sciences of nature and of microscopy was influenced by continental historians up to the 1980s, and the issue is lately become topical among English-speaking historians. Notably, the recently-

published works by Fournier and Ruestow discuss historical, social and scientific dimensions of microscopy, though principally related to seventeenth-century. The established subjects of each tradition, as well as their methodologies, are mainly different, though some authors encouraged to make links between each trends, and one

1 See the works by Turner 1990 (Instrument), 1980 (Microscope), Ford 1985, 1991, Bracegirdle 1978b, Bradbury 1967, Clay and Court 1932.

of the goals of the two above-mentioned works was partly to unbolt the frontiers between the history of the microscope and of the microscopy.

Nevertheless, there is also shared knowledge among historians of the microscope and historians of natural sciences, especially in regard to the opposition between

seventeenth-century and eighteenth-century microscopes and microscopy. It is said that there was practically no optical improvement of the microscope during the eighteenth- century, although such is the epoch in which many morphological improvements led the microscope to acquire its modern shape.² But, as a consequence of the former thesis concerning microscopes, eighteenth-century microscopy is always presented under an unfavourable light in comparison to the seventeenth and nineteenth-century studies.

Such a strategy strengthens the contrast between the “good research” carried out in the seventeenth-century and the “amateur work” of the eighteenth-century. As Maria Rooseboom typically puts it: “After the great discoveries of the pioneers, the 18th- century brought little sensational news in the fields of microscopes and microscopy”.³ Held by historians of the microscope long before the 1960s, this argument did not really change in the updated and more recent version, assessing that the seventeenth-century scientific programme of microscopy was not carried on during the Enlightenment.⁴ Nevertheless the studies that addressed new issues such as those by the French historians who, in the 1960s, started examining the impact of eighteenth-century microscopy on emerging fields such as metallurgy, mineralogy, and microscopical papermaking, did not generate other works. This situation is not an exception, and one can too often gather data from a wide range of authors who, though not integrated into both traditions, bring essential information to the issue. When working on the European

2 The reference for the morphological improvement of the preachromatic microscope is Clay and Court 1932 (abbr. C&C). See also Laissus 1961, 569 and Policard 1932, 209-211. G. l’E. Turner ([1972], 4) commenting C&C’s brilliant work on the development of the microscope morphology decided that they did not address any other issue, especially that of the optical improvements: “Nowhere is there any consideration at all of the optical system of the microscope”. But actually the table of contents of C&C’s book shows that they widely discussed the development of optical properties.

3 Rooseboom 1956, 7.

4 Ruestow 1996, 276.

context, the large spreading of information --primary sources as well as secondary literature-- is a permanent obstacle one might not underestimate the influence.

Another consequence deriving from the above thesis is the necessity to account for the discrepancy between data showing that a large amount of many types of microscopes was built during the eighteenth-century, and the absence of a microscopical programme.

What were the microscopes used for? Historians have replied that their use was restricted to entertainment: “In the early [sic] part of the seventeenth-century workers such as Hooke and Grew and Powers had used compound microscopes for serious scientific work. By the middle of the eighteenth-century it had largely come to serve as an instrument for amusement”.⁵ As well, recent historians consider that “The

programme of microscopy does not survive into the eighteenth-century as a resource for natural philosophy except at the relatively popular level”.⁶ Although, as was shown by Ruestow and Fournier, the Netherlands seem to have carried on the previous interest in microscopy during the first half of the century, it was argued that the decline of

microscopy started between 1690 and 1710,⁷ and quickly inaugurated a period in which microscopes were mainly prized as decorative and entertaining toys: “With the

exception of the Netherlands, in various parts of Europe a general consensus among many physicians and philosophers was shaped around the years 1690-1710. It credited microscopy with a fancy-illusory and theoretical status (in the pejorative sense), that restricted it to an entertaining and useless activity”.⁸

In the present state of historical research, a consequence is that eighteenth-century microscopy has been very poorly examined, especially when contrasted with the large

5 Bradbury 1967, 152. To check the seriousness of these assertions, everyone will agree that the 1660-1680 period that saw the publication of the works by Power, Hooke and Grew, is the “early part of the seventeenth-century”. My italics. Turner ([1972], 12) also discussed the relation between science as a popular pastime and development of the market.

6 Bennett 1997, 72.

7 Fournier 1991, 4, 16-17.

8 Mazzolini 1997, 219. See also on the microscope and other instruments considered as toys, Fournier 1991, 2; Turner [1987], 378-385; Turner [1973], 19.

quantity of studies that deal with the seventeenth-century. Let us analyse more in detail the claims and issues of each of these traditions.

1.1. The history of the microscope and its contribution to the history of eighteenth- century practices of the microscope.

Dating back to the nineteenth-century, the classical Dutch and British histories of the microscope have displayed a considerable amount of data about preachromatic microscopes,⁹ which are the only type of instruments considered in my work. Many catalogues from public and private museums of scientific instruments conserving antique microscopes are nowadays available, written since the first part of the

century.¹⁰ In the history of the preachromatic microscope, the large disparity between the clear-cut British-Dutch tradition, and the works by the rest of Europe is also typical of this stream of research. Except the substantial chapters Daumas wrote on

microscopes, there is indeed no recent book comparable to Clay and Court’s (1932) for France, Germany and Italy.¹¹ I mean a comprehensive work on the development of optical and technical aspects of preachromatic microscopes and related tools, like the camera obscura, the microtome or the microscopical preparations.¹² Clay and Court have brought strong evidence for the above-mentioned thesis: microscopes did not undergo major optical advances, though their morphological aspect improved during the eighteenth-century, as to fit with scholar’s demand for special kinds of observations.

The latter point was convincingly established through a comprehensive survey of the evolution of the microscope, especially for the case of England.¹³

During the period considered as the decline of interest in the microscope, at the beginning of the eighteenth-century, two new types of microscopes were nevertheless

9 C&C 1932, Hogg 1867, Harting 1866.

10 Purtle et al. 1974, van der Star 1953, Van Cittert 1934, Nachet 1929, Disney 1928. For a survey of the catalogues, see Nuttall 1979.

11 Daumas 1953, 199-229, 324-385.

12 The works of Lualdi 1995, 1996, 1999, Turner 1991, Bock-Berti 1983, and Bedini 1963 have supplied data concerning Italian microscopes. Nowak 1984, de Martin 1983, Allodi 1967, and Hintzsche 1949a, b, c have provided information concerning German microscopes. On the development of the microtome, see Bracegirdle 1978a, 12-21 and Frison 1972, 95.

13 The relations between Henry Baker and John Cuff, and John Ellis and Cuff are paradigmatic of these types of relationship between the user and the producer, see Lenhoff and Lenhoff 1986, 35-36; Ford 1985, 112; Turner [1974], 63-64.

built: the Wilson (a simple microscope^g) in 1702, and the Culpeper around 1725 (a compound microscope^g). The renewal of the microscope trade in London in the 1740s was marked by the improvement of the Culpeper type and by the construction of two new models: the solar microscope, that allowed the projection of magnified images on a wall, and the microscope for opaque objects. If “communal observation” was

encouraged by the solar microscope,¹⁴ both dynamism of the competition among British instrument makers and their relations with scholars asking for improvements of the instrument led to ameliorate many aspects of the simple and double microscopes.

The leading instrument maker involved in those changes is John Cuff (1704-1772).

Among other innovations, Cuff gave the microscope its modern shape, designed a stage free from disturbance when manipulating, and improved the system of the screw to adjust the focus. He also added a movable mirror to the solar microscope and built a stand on which the Wilson hand-microscope could be fixed. Other instrument makers built microscopes advertised as universal, like George Adams (1709-1772) or Benjamin Martin (1704-1782).¹⁵ After that relatively dynamic period, the attention towards microscopes vanished during the second part of the century. Thus, in 1759, the method invented by John Dollond for the construction of achromatic flint lenses for telescopes was not suitable for producing achromatic images when applied to the microscope.¹⁶ The importance achieved by the Cuff double microscope of 1743 led historians to consider that many continental instrument makers copied this model.¹⁷

The focus on English instrument makers leads me to outline a current belief stemming from this trend. Generally speaking, the London microscope-makers are viewed as European leaders in conceiving, building and selling microscopes all over the century.¹⁸

14 Walters 1997, 141.

15 C&C 1932, 173: “In 1759 Martin uses the term [universal] in a still further sense, to indicate a microscope in which the body is so mounted that it can be moved both in arc and radially by lengthening the transverse arm, so that it can be brought over any part of the stage.”

16 Daumas 1953, 212.

17 C&C 1932, 141.

18 Nuttall 1979, 8-13; Pipping 1977, 101; Turner [1976], 1; Turner [1973], 21-22; Taylor 1966, 57-58.

Many other microscope-makers and especially the continentals are believed to take their morphological models from the Wilson, Culpeper and Cuff types, all invented in London. Consequently, creativity and production of microscopes move one-way from England to the Continent, overwhelming the rest of Europe. To moderate this view, some historians nevertheless mentioned the fact that no model or accessory for the microscope is uniquely British. For instance, from Harting we know that the Wilson is an improved version of a model pictured by Nicolaas Hartsoeker (1656-1725), the figure of which was engraved in his 1694 Essai de Dioptrique. Other historians have stated that the field-lens --a lens set between the ocular and the objective, that widens the field of vision-- was introduced by Johann Wiesel (1583-1662) of Augsburg in 1654, and imitated during the next century by many microscope makers.¹⁹ As well, adjustment screw existed since the seventeenth-century.²⁰ Clay and Court have also showed the influence of the Berliner anatomist Johann Nathaniel Lieberkhun (1711- 1756) who, around 1738, introduced into England the solar microscope and the microscope for opaque objects. Nowadays, historians of the seventeenth-century microscope have recognised the influence, at that time, of Italy, where the “best, innovative optical instrument makers were found as well as the best optical glass”.²¹ Even the first micrometer fitted to a microscope was not invented by a British, George Adams, who advertised it as a major tool for his universal microscope in 1738. He owed the invention to the German mathematician Christian Gottlieb Hertel (1683-1743) who fitted one of his microscopes with a micrometer already in 1716.²²

An important issue turns over the question of the leadership of the British trade for instruments. My work that deals with the use of the microscope indeed can not avoid the question of what precise kind of microscopes were used by scholars, where, and for what. Actually there are no systematic evidences allowing to confirm the British

19 On Johan Wiesel, see Daumas 1953, 119-120, 20 On the adjustment screw, see Bedini 1963, 409, 421.

21 Bennett 1997, 66.

22 C&C 1932, 155-156.

primacy, and many questions are still left to be raised: to what extent were the British instrument makers leaders on the Continent, and what were the local areas for their exportation? What was the importance of other local markets? Were there other important workshops able to compete with the London instrument makers? On this point, Peter de Clercq, in his 1991 article, already demonstrated the existence, between 1660 and 1750, of a large Dutch workshop that advertised and sold mathematical instruments and microscopes to the whole of Europe. The Musschenbroek family in Leyden ran the workshop for three generations, they broke into the European market and were for instance the first to issue catalogues of their instruments with fixed prices in 1736.²³ De Clercq’s research led to a reappraisal of the pre-eminence of London’s instrument makers. Antonio Lualdi as well provided evidence of several important workshops in Italy, Venice and Milan, while Daumas demonstrated that Paris was an important place for instrument makers.²⁴ To such a debate that touches important points like the specialisation and professionalisation of instrument makers, I shall bring in chapter 4 data taken from the sources, that will likely help to grasp the differences in the markets for microscopes among the main countries of Europe. For instance, Douglass Taylor highlighted a social difference between the French aristocrat (Duc de Chaulnes) and the English uneducated craftsman (Jesse Ramsden), who worked on a similar object, the instrument for precise and microscopic division.²⁵ But, except for the case of England, we know approximately nothing about the social status of the

instrument makers, the means and ways of their advertising, the material and techniques they used, and their relation to the scholars.²⁶ Knowing indeed the relative importance of local and international trade for microscopes will allow to better understand the use of the microscope.

23 de Clercq 1988, 1991,

24 Lualdi 1995, 1996, 1999, Daumas 1953, 97-113, 339-385.

25 Taylor 1966, 59.

26 On these aspects, see Taylor Brown 1984, 3-5; Turner [1976], Turner [1966].

Another trend in the tradition of the history of the instrument relates to empirical studies on the optical properties of the microscopes. I will not speak here of the measures of powers of the remaining microscopes from Leeuwenhoek,²⁷ but of other microscopes.

Edward Frison already in 1948 measured the magnification of some French and British microscopes built in the middle of the century. Bradbury then measured, in 1967, the optical properties of thirteen microscopes dated between 1690 and 1790. According to him, optical properties were mainly insufficient to undertake observations, and almost every lens presented chromatic and spherical aberration^g. Given the defective lenses, no scientific research could be carried out in the eighteenth-century.

Edward Frison is perhaps one of the few who spoke out against such a deductive consequence. In his 1972 book he challenged Bradbury’s claim and highlighted the striking contradiction between discrediting the optical properties of the eighteenth- century microscopes and the weak amount of quantitative data regarding the

microscopes from this period. When measuring systematically the magnification^g and resolving power^g of the microscopes from the Van Heurck Museum, Frison indeed found remarkable and unexpected qualities in their optical properties. He drew from his survey the conclusion that a common Culpeper microscope produces images as good as a nineteenth-century achromatic microscope from Chevalier built in 1835.²⁸ So

important a thesis, in contradiction to that of Bradbury, was indirectly reexamined by Bracegirdle, who in 1978 measured 25 microscopes built between 1660 and 1800.²⁹ Almost none of them reached a magnification higher than x100.³⁰ Their resolving power increases from 3m in the seventeenth-century to 2m in the next century,³¹ and Bracegirdle stated that, optically speaking, a typical microscope from the eighteenth-

27 The measure (x270) was first taken by Harting in 1850, see Dobell 1932, 323-326. For more recent accounts, see Fournier 1991, 26-27; and Ford 1991, Ford 1985, 60-75 for the history of remaining microscopes of Leeuwenhoek.

28 Frison 1972, 123.

29 Bracegirdle 1978a.

30 Simple microscopes belonging to Bentham, Robert Brown and other early nineteenth-century scientists reached the power of x170, according to Ford 1985, 141-142.

31 Bracegirdle 1978a, 193.

century was to be considered the Culpeper. Still the technique of measuring the power remains an exception, and is usually not used in the descriptions of microscopes from catalogues of instruments. Moreover, one can ask why, if the resolving power of the seventeenth-century microscopes was poorer than that of the next century (3m against 2m), how could the “serious scientific research” of Malpighi, Power, Grew and Hooke have been carried out with such “bad” instruments? What is indeed the meaning of these surveys? Methodologically speaking, these inquiries would gain in historical value once we would know something concerning either the owners of the microscopes measured or the observations undertaken with them. Which, with a few exceptions, we unfortunately do not. Perhaps the microscopes they measured were only used for scientific work, or never; who knows? So how can one infer from this high-tech package of data the least consequence about eighteenth-century microscopy without looking at the use of these microscopes?

Except for what concerns seventeenth-century authors, it is a more recent trend to try to identify, through printed and manuscript sources, the sort of microscopes used by scholars. Jean Anker, Erich Hintzsche, Brian Ford, Virgina P. Dawson, Julius Groner, Philipp Sloan, Marta Stefani and Giulio Barsanti have discussed identification of microscopes of Müller, Haller, Linnaeus, Trembley, Henry Baker, John Ellis, Buffon, Needham and Spallanzani.³² Nevertheless, and in a symmetrical way to the above- mentioned works, there is not so much left to hope from such kind of studies, unless we can identify and recover in a museum or in private collections the true instrument that was employed by the microscopist to observe a specific object. Indeed one of the main problems of eighteenth-century use of the microscope is the relative lack of

standardisation in the manufacturing of the microscopes. Craft working conditions of grinding the lenses, and poor methods of control explain why two same powers built by the same instrument maker for the same model can vary enormously in resolution and magnification. Moreover, there is much evidence indicating the complete autonomy of

32 Barsanti 2000, 179-188; Stefani 2000, 162-166; Groner & Cornelius 1996, 111-130; Sloan 1992, 421-424; Dawson 1987, 86; Ford 1985, 112-115; Hintzsche 1949d, 104; Anker 1943, 195-196.

the optical system and the type of microscope used by scholars. Indeed Réaumur, Trembley, Saussure, Fontana, Gleichen, Ledermüller claimed to have adapted to their microscope lenses which they had bought separately from the microscope itself.

Curiously, such a crucial idea that clearly stems out of Bracegirdle’s and Frison’s inquiries, was not discussed in their papers, though the lack of standardisation is a major characteristic of the microscopes of that time, which the scholars had to

permanently deal with. In terms of method, my claim is here close to that of Gerald l’E.

Turner, who has highlighted that decorations tools for microscopes are not reliable marks enabling historians to identify their original maker.³³ Unless recovering the true instruments, identifying the kind of microscopes used by scholars will likely acquire more meaning when systematised through comparative surveys and statistical inquiries enabling the historian to discuss the following topics: 1. Challenge, amend or confirm the thesis of the leading role of British microscope-makers in Europe. 2. Bring precise data showing the respective importance of the simple, compound and other microscopes as used in research. Brian Ford indeed claimed that up to the time of Robert Brown (1832), discoveries were made only thanks to the simple microscope. However, postmodern history is concerned with construction and deconstruction more than with discovery, although both have a place in the history of science.³⁴ Historians have alleged as well the Enlightenment scholar’s distrust in the compound microscope,³⁵ so that further investigation synthesising sources from a wider range of countries would allow to clarify what is the general trend in Europe. 3. Investigate the strategies used by scholars to by-pass characteristics such as chromatic and sphericity aberration. 4.

Understand how the question of standardisation was considered, and how did scholars tackle the problem with respect to the eighteenth-century known epistemological

standard of repeating experiments and observations.³⁶ 5. Supply information about local

33 Through a large survey, Turner [1966] has shown that the same decorative pattern was to be found on microscopes signed by different makers, and vice-versa.

34 On this tension between discovery and construction, see Brush 1995, 228-229.

35 Ruestow 1996, 14-15, 287; castellani 1978, 59. This is also the thesis advocated by Ford 1985.

36 On repetition of experiments in seventeenth-century physics, see Garber 1995 and S&S 1985, 55-65. On repetition in physiology, see Duchesneau 1982, 152-156 and Belloni 1970.

and international trade, in order to shed light on the differences between the various networks of scholars “microscopists”. Chapters 4, 7 and parts of others chapters will be dedicated to this research.

A study of Enlightenment microscopy needs to reflect on the conditions of the reproduction of knowledge within a social sphere that employs non-standardised

instruments, of which the microscope is among the best representatives. Historians have calculated magnification for microscopes which no one can prove when and where they were used, and they ignored any mention of the interchangeable lenses used by

scholars. This could be extra evidence against using the technological methods in the history of the microscope, as outlined above. Indeed, the scholars of the eighteenth- century did not use the microscope as a ready-made instrument. Rather they use do-it- yourself as a normal expedient of research, fitting a lens made by their brother, friend, colleague, amateur or professional craftsmen.³⁷ There are many examples of this. Do-it- yourself, bricolage and trial and error were common practices shared by eighteenth- century microscopists, and it would be absurd to neglect such a constitutive aspect of Enlightenment scientific activity. So much so that I believe that no one can legitimately deduce anything from a given microscope about the quality of image it historically produced and about vision, either good or poor. Studies done in such a spirit have a documentary interest rather than an epistemological or conclusive value, because it can not be proven that the actual microscope was used in the eighteenth-century with the same lenses with which it is currently fitted. This permanent do-it-yourself attitude of the Enlightenment scholars responds fittingly to the lack of standardisation of the microscope. Given that these scholars were aware of the “imperfection” of their instruments, standardisation was rarely attainable, except at a the level of local

37 For example in October 1744, Trembley said he had changed the lens of his microscope (CRT 1943, 210); Ginanni (1747) used a lens made by his brother; Saussure, in March 1766, fitted a Cuff simple microscope with a lens from Trembley (BPU: MS 64, Agenda, n.p.); Targioni-Tozzetti (1943, 19) in June 1766, fitted the best lens of a Culpeper microscope to a solar microscope by Lieberkhun. Villars (1804, 95-96) adapted a compound microscope by the French maker Rochette, to his Lyonnet

microscope.

communities, it appears that the main problem was one of communication, which I will discuss below.

Another aspect of the classic museological tradition of the microscope is its relative lack of strong conceptual and theoretical foundations, that hinder it embodying the problems encountered by eighteenth-century scholars in the social, cognitive and historical contexts they belonged to, issues which other studies have addressed.³⁸ By contrast, recent historians of scientific instruments have charted an important trend that developed during the second half of the eighteenth-century, and have discussed several questions like the growth of quantification in science, the need for standardisation and the research undertaken to improve instruments. Frängsmyr and Heilbron have thus characterised the second part of the century by a wave of quantification which participated in the technological take-off of the Industrial Revolution.³⁹ If the

“quantifying spirit” is to be found, for instance in demography, mathematics, meteorology and natural knowledge, it also concerns the development of scientific instruments since the 1760s.⁴⁰ The instruments for measuring (barometers,

thermometers, eudiometers) and surveying (telescopes) were built with increased precision at that time. To this trend can be linked the standardisation of weights and measures that spread all over Europe after the French Revolution. A factor affecting the development of mathematical and optical instrument building was their nautical

applications related to the expanding development of commercial travels as well as that of military needs.⁴¹ Along with the emerging trend of technology during the same period, these factors helped to progressively transform the way of making instruments,

38 Butler et al. (1984, 1-23) presented the social advertisement and the reaction of public opinion to the progressive linking of microscopy, bacteriology and hygiene during the second half of the nineteenth-century. Gooday 1991 showed that the microscope helped disciplining domestic practices during Victorian era. According to Walters (1997) the eighteenth-century ideology of promotion of instruments fitted the culture of polite science in Britain, and especially organised the conversation with the female audience.

39 Frängsmyr et al. 1990, Cardwell 1972, 111-112.

40 Heilbron 1990, 3: “The instrumentalism was a key ingredient of the quantifying spirit after 1760”. See Frängsmyr et al. 1990 for a detailed report of the spreading of the quantifying spirit in Europe, and A. Turner 1989 for the improvement of scientific instruments in late Enlightenment France.

41 Heilbron 1990, 6; Moskowitz 1986, 12; Daumas 1953, 123-124.

building up a demand for more precise and mathematical studies of instrument making.

The change of needs, coming from many sectors of the societies, led to many

improvements of the techniques. Of course, England, Holland, France, Germany and Italy present in many respects different forms of technological cultures. For instance, visibility and advertisement, social status of the instrument makers, business practice as well as the relationship with the scholars are some of the points by which an Italian instrument maker lived in a world totally different from that of a British or of a German craftsman. Yet all of them also belonged to a world where technology was

progressively transforming the society.

Concerning the microscope, the question is what is its place and the place of related instruments, such as the camera obscura or micrometer, in the general development of quantification in science that took place during the second part of the century. The major question is whether the development of the practices of the microscope was or not in time with the expansion of technology in Occident? Or, according to the tradition, did microscopy stagnate, being far removed from the general trend, and in what respect? What is the form the quantifying spirit took in building microscopes and in using them within scientific communities? Did the microscope improvements only happen in the early nineteenth-century, mainly managed by the known instrument makers Joseph Fraunhofer (1787-1846), Charles Chevalier (1804-1859), Joseph Jackson Lister (1786-1869) and Giovanni Battista Amici (1786-1868)?⁴² Did these improvements represent a full rupture with works and problems originated in the previous century?⁴³ Or did the question of achromatism find its roots eighty years before the issue became topical in the 1830s, when these makers provided original solutions to problems already raised and discussed by scholars during the

Enlightenment? Matthias Dörries has recently regarded the better description of the

42 See Nuttall 1979, 14-24; Turner [1972], 13-15 and C&C 1932, 231 for the development of the achromatic microscope between 1800 and 1860.

43 Such is the position appearing in Dörries 1994, 13; Turner [1967], 162; Bancher & Holz 1961, 269; Hughes 1959, 8-9, 59.

instruments and the measurement of their resolving powers as topical practices explaining the process of “transforming instrument into objects of research”,⁴⁴ that developed during nineteenth-century. This process led scientists to justify the choice and use of their instruments, to describe their performances and define some standards.

The German Friedrich Adolf Nobert (1806-1881), who engraved micrometric plates with a diamond in the 1840s, is famous in this respect.⁴⁵ As regards eighteenth-century, the point at issue is whether such reflexive nature of experiment --as an investigation of the instrument by the scholar and the instrument maker-- also existed during the

Enlightenment, and to what extent. We already know that since the 1750s, microscopes were objects of the research of Leonard Euler, John Dollond and Klingenstiern.⁴⁶ They are but the tip of the iceberg and many other scholars and instrument makers were involved in the research for achromatical lenses, which became a question discussed everywhere in Europe around the 1760s.⁴⁷ Achromatism brought together an important network of scholars from many disciplines --mathematics, physics, natural history-- who started to draw a regular line of collaboration with instrument makers, to which I will bring further investigations. I shall obviously not examine hereafter what was the respective importance of the standardisation of manufacturing and of the optical

improvement of the microscopes in the early part of the nineteenth-century,⁴⁸ but rather draw Enlightenment’s roots of modern attitudes of research towards the microscope and its uses.

In chapter 7, I will then show in what respect the microscope related to quantification, then I shall gather data showing the pros and cons of parallelism in the rhythm of the research on microscopes, with those for the development of scientific instruments. Did

44 Dörries 1994, 32-33.

45 Dörries 1994, 25-29; Turner [1967], 164-170.

46 See the oncoming work by Richard Sorrenson, François 1961, Boegehold 1943.

47 Proverbio (1989) has reconstructed the collaboration between the mathematician Boskowich and Giovanni Stefano Conti in order to discover the secret of the flint glass, an essential component of achromatic objectives made by the Dollonds.

48 See on the standardisation and calibration technique of the Bavarian instrument maker Fraunhofer, Dörries 1994, 3-4, 12-14, 23-26; and Jackson 1994, 555-557.

the microscope participate in such a major process of the rationalisation of technology, up to what point, and according to what modalities? Whether or not the

Enlightenment’s spirit of quantifying also encompassed microscopes will then clearly show if the microscopes did belong to the scientific world or to that of entertainment.

1.2. Microscopy and the tradition of history of “biological” knowledge The tradition of history of “biological” knowledge I shall now deal with mainly contrasts with the British-Dutch history of the microscope. The former examined the theories and practices of natural science without particularly stressing the microscope, and, since the 1960s, put a strong emphasis on the quarrel of generation. But there is a common thinking shared by both traditions, when they focus on the microscope’s

“negative influence” on the development of knowledge on nature. Already in 1934, Charles Singer noticed that “the writings of the micrographs of the classical period (with the exception of Grew) give the impression of a work without method nor

determined goal”.⁴⁹ Guyénot, one of the first French historians who initiated studies on the history of biological thought, states that “The discovery of the microscope did not produce results one could logically expected from it (...) Nobody devised the existence of animal cells”.⁵⁰ Nevertheless, the later works in this tradition did not concentrate on the use of the microscope and seldom tackled the issue directly. Historians have usually discussed the microscope only within the context of wider issues: philosophical

implications,⁵¹ microanatomy, artificial fecundation, embryology, spontaneous

generation, “spermatology” and classification. I will discuss in more detail the latter of these topics in the next chapters.

The historical circumstances of the decline of microscopy between 1690 and 1710 are a topical issue for the understanding of the transformation of microscopy and its status

49 Singer 1934, 174.

50 Guyénot 1941, 442.

51 On the philosophical implications of the microscope, see Wilson 1995, Parigi 1993 and Solinas 1967.

during the eighteenth-century. In her 1935 brilliant paper, Marjorie Nicolson demonstrated the caustic influences exerted by writers and reporters on the fall of microscopy in England at the end of the seventeenth-century. She showed that from the 1680s onwards people other than academics competed in cracking public’s attention up by dropping scathing irony on the Royal Society. They published pamphlets and satires, and performed plays that made scientific activity look ridiculous, especially

microscopy. Satirising women’s interest in experimental studies and, most of all, their microscopical observations, lead public opinion to thus consider the work of

Leeuwenhoek, Grew or Hooke as totally useless.⁵² Later Belloni had considered that quacks who used the microscope also contributed to the “latent period” of microscopy during the enlightenment.⁵³ Afterwards, except the studies on Henry Baker,⁵⁴ historical works seldom got to the point of understanding the reactions of scholars, in the

eighteenth-century, to such public attacks. Notably the question was not examined regarding France and Germany. Did really the scholars stop producing microscopical works or did they modify the level of visibility of their works by using some new strategies for their publications? Is the London milieu the prototype of the European attitude towards microscopy, or is it just limited to London? In France, the works of Louis Joblot (1645-1723), who wrote the first treatise on microscopical animalcules in 1718, have been thoroughly underestimated, considered either an imitation of

Leeuwenhoek’s work, or welcomed by a lukewarm reception with no influence on further research. Contrary to this, chapters 2 and 8 will show that Joblot’s work topped off the first wave of research on animalcules, providing the first consistent

antispontaneist system of experiments.

Nicolson’s and Belloni’s studies are not the only one tracking some of the factors accounting for the “decline of microscopy”. For a decade historians have focused on academic contexts such as central Italy and the Netherlands. In Bologna, the quarrel

52 Nicolson 1935, 22-37.

53 Belloni 1961, 587.

54 Mazzolini 1997, 217; Turner [1974], 61-65.

between the physicians Sbaraglia (1641-1709) and Malpighi (1628-1694) at the end of the seventeenth-century, led the conservative “empirical Galenist” academic party to get back, against microscopic investigation, their authority on anatomy and other lectureships.⁵⁵ A convicting argument raised in the issue was that microscopy was useless to the lasting Galenist therapeutic frame, as well as to the Materia medica.⁵⁶ So that, generally speaking, these events account for the fall of microscopy in anatomy, and historians have stressed the point that the seventeenth-century Malpighian programme of anatomical microscopy was not continued during the Enlightenment.⁵⁷ Nevertheless, in other fields such as embryology, historians also showed that later microscopical works by Albrecht von Haller (1708-1777) and Caspar Friedrich Wolff (1733-1794) were indebted to seventeenth-century scholars, especially to Malpighi’s works and methodology.⁵⁸

Regarding the Netherlands, Fournier and Ruestow, though mainly concerned with seventeenth-century Dutch scholars, have also discussed some cases in eighteenth- century microscopy. The latter has shown that the micro-anatomical programme was mainly abandoned during the first half of the century with physicians and anatomists like Ruysch, Boerhaave and Muys.⁵⁹ To understand the obstacles to eighteenth-century microscopy, Ruestow invoked several arguments: the negative role of cartesianism which demanded rational comprehension, the tradition of miniature painting which entailed iconographic conventions, as well as theological obstacles which induced people to contemplate things more than to observe them.⁶⁰ Fournier studied three Dutch naturalists, Job Baster (1711-1775), Martin Slabber (1740-1835) and Leendert Bomme (1727-1788), who kept alive the seventeenth-century tradition of microscopical

55 Cavazza 1997, 140-142.

56 Guerrini 1997, 117-120; Cavazza 1997, 132-134, 140.

57 Bennett 1997, 72.

58 Bernardi 1992, 44; Monti 1990, 151; See Mazzolini 1977, 220-224 on the microscopical techniques used by Haller for the embryology of the chicken.

59 Ruestow 1996, 170, 291-293.

60 Ruestow 1996, 62-80.

observation and illustration.⁶¹ Nevertheless, statistical surveys on the amount of leaflets and microscopical works annually printed in Europe, presented by Hans Peter Nowak and by Fournier credited the decline of microscopy around 1700 with the objectivity of numbers.⁶²

The main questions I will address regarding the early eighteenth-century decline of microscopy are the following. What more precisely is the situation of microscopy in other cities such as Nuremberg, Paris, and Florence? Was the “decline of microscopy” a decrease of the production of microscopical studies, or just in the visibility given to the production, or both? If the latter hypothesis turns out to be more reliable than the previous standard interpretation, which reifies the apparent decline into a real break of production, I could be led to read in the so-called “decline of microscopy” the mark of an important epistemological rupture between the scholar’s world and the public. Such an important change could have affected the forms of communication of the scientific knowledge, especially when showing only selected aspects of the scholar’s production to the public. When considered a reaction of the scholars against public criticisms, microscopy would have turned partly invisible, used as a routine tool adapted to transverse practices with low visibility, in a sphere in which the control of procedural and conceptual knowledge would theoretically tend to avoid any critical and “non- expert” intrusion from outside. But in order to be shaped as a routine instrument, the microscope might have been employed to examine particular objects, which, in the first forty years of the century, were mainly insects and cryptogam. Small-scale creatures, studied through their generation and their ambiguity in belonging to a particular kingdom, provided the first microscopical objects of the eighteenth-century, observations that every scholar managed to repeat easily. This construction of new democratised microscopical objects, which corresponded to a rejection of a part of the

61 Fournier 1987.

62 Fournier 1991, 12-17; Nowak 1984, 5.

seventeenth-century microscopical approach, will be the main subject of part I (chapter 2).

The second dimension I shall examine is whether or not the rest of Europe followed topical London and Bologna example in their apparent rejection of the microscope. Or whether other cases in Europe are closer to the Dutch, and if there are other unknown models for the development of microscopy during the first half of the eighteenth- century. To take a comparative example in Germany and Italy, T. Saine showed that during that period, the new German literary culture ends in a “ideology of nature” for which the microscope and the telescope represent highly symbolical instruments. In Italy, influenced by the contrast between “poor” microscopy and the importance of the Galilean tradition, historians still consider that the microscope did not produce a

“scientific revolution” compared with that which occurred thanks to the telescope.⁶³ By contrast, in Germany the new form of culture “takes place simultaneously on the levels of science, theology, metaphysics, and psychology”.⁶⁴ Between 1720 and 1760, poets like Barthold Heinrich Brockes, Klopstock or Christlob Mylius (1722-1754) sing the praises of the microscopic and telescopic discoveries,⁶⁵ and they are followed as well by natural theologians such as Lesser (1692-1754). In France and England, natural theology, represented for instance by l’Abbé Pluche’s Spectacle of Nature, and by William Derham’s Physicotheology, was the object of many ironical attacks in the middle of the century,⁶⁶ that led to the diminishing and almost to abandon this way of disclosure. Nothing in Germany seems comparable to the caustic pamphlets and scathing remarks written by Addison, Swift, Voltaire, La Mettrie, Diderot and Buffon against academics and natural theology, in which microscopists are the continual target of sarcasm.⁶⁷ Perhaps also there is no target in Germany like English and French polite

63 Bernardi 1995, 113-114.

64 Saine 1976, 62.

65 Saine 1976, 64-67.

66 Dawson 1994, 83-84; Roger 1993, 561.

67 Mazzolini 1997, 210; Nicolson 1932, 30-32. Needham’s reputation was strongly ridiculed by Voltaire who called him l’Anguillard, the “eeler”, a word echoed by Diderot in Le rêve de d’Alembert.

science that carries the culture of conversation.⁶⁸ In the northern and north-east part of the Continent, the influence of natural theology lasted during the whole century, and thus participated in the spread of a well-disposed image of the microscope. As well, the microscope and the theories it allowed to produce, defended by Leibniz, Wolf and Kant, was not the object of a quasi philosophical prohibition as in Berkeley’s New Theory of Vision (1709).⁶⁹ There are probably only few similar things shared in the representation of the microscope among the main European countries, Germany, England, the

Netherlands, France and Italy.

The second half of the Enlightenment, or more precisely the 1740s onwards is known as a period displaying a very different pattern than the first half of the century. Leaving aside some microanatomical discoveries --identification of the axon by Fontana, morphological studies on the blood cells by della Torre, Hunter, and Fontana,

generalisation of the discovery of lymphatic vessels by Mascagni and Hunter-- many studies have emphasised the how and why of the regeneration of polyps, of the parthenogenesis of green flies and the renewal of spontaneous generation.⁷⁰ John Farley, for instance, has traced the periodisation of the trend in spontaneous generation and he has established the existence of three periods: first the spreading of the Redian programme omnia ex ovo until the 1750s; second, attacks from Needham and Buffon against the paradigm in the middle of the century and strong reactions from many parts of Europe between 1750 and 1780; third, the triumph of spontaneous generation from 1780 to 1830, a period charted also by Rostand.⁷¹

National styles in the history of science have lead historians to focus on some particular scholars and to widen the research on these heroes. Leeuwenhoek’s works especially

68 On polite science in the first part of the century, see Walters 1997.

69 Brykman 1995, 134-135; Wilson 1995, 248; Parigi 1993, 161; Roger 1993, 461-462; Solinas 1969, 57-58, 188-191. For instance, Wolf (1744, 61) illustrated the “distinct notions” by an analogy with the microscope.

70 Vannozzi 1996, Clarke 1960, 135-137; Allodi 1955, Hoff 1959. On spontaneous generation, see Roe 1982, 1983; Farley 1977.

71 Farley 1977, 17-46; Rostand 1943, 73.

were thoroughly examined, but most of it are celebrative works.⁷² Before the importance and the amount of microscopical research undertaken by the Italian physicians and naturalists in the second part of the eighteenth-century --della Torre, Fontana, Corti, Mascagni, Spallanzani-- the modern Italian historians could indeed not deny the existence of research programme in which the microscope was a necessary tool. In that respect, they identified heirs to Malpighi, “the founder of anatomical microscopy”,⁷³ for he established a programme of research that grounded the anatomico-pathologic programme by Giambattista Morgagni (1682-1771) between 1710 and 1770,⁷⁴ though, strictly speaking, microscopical anatomy was not developed by him. But continuity was established for the tradition of organic physics. Historians have indeed claimed continuity between Malpighi’s works and later works by

eighteenth-century natural experimentalists, mainly Antonio Vallisneri (1661-1730) and Lazzaro Spallanzani (1729-1799).⁷⁵

Nevertheless, before these historiographical traditions, one is lead to ask whether or not they have neglected international and exchange factors in their account of the practices of the microscope. Jacques Roger showed that the generation quarrel owed much to the French philosophers, to Descartes, and to eighteenth-century Philosophes. Bernardi replied in 1986 by showing that the quarrel started as an Italian issue in the second part of the seventeenth-century, and similarly died in Italy near the French Revolution, with the death of Spallanzani (1799). Germany also developed some schools of microscopy, as in Nuremberg and later in Berlin. Bracegirdle reinforced such an isolationist

approach by saying, about eighteenth-century microscopists, “People worked in isolation, and the coincidence of their interest being in things small seems to produce a coherence which is in fact lacking”.⁷⁶ A factor somewhat neglected, especially in

72 See Ford 1991. Brush (1995, 230) has distinguished celebratory and amateur historians from scientists who brought important contribution to knowledge.

73 Belloni 1961b, 585. See also Bertoloni Meli 1997.

74 See Cavazza 1997, 141; Boaretti 1990, 94-95; Belloni 1979, 140-144; Belloni 1971, 103-104.

75 Bernardi 1986, 393-394. See also about Spallanzani, Castellani 1992, 1994.

76 Bracegirdle 1978a, 12.

Bracegirdle’s account, is the importance of the scientific exchanges in the development of eighteenth-century systems of scientific practices, which include extensively the use of the microscope. It is likely not that “there was no organisation of research until later in the nineteenth-century”,⁷⁷ but the organisation of the knowledge was different and not so systematised as it became later. Enlightenment being the century of

correspondence, the exchanges between scholars --and especially related to the

microscope-- can actually not come into view without reading the enormous amount of letters either published or still being in archives. Moreover, since the 1980s, many studies showed the importance of European exchanges in technology, in chemistry or among scholars implied in the quarrel of generation.⁷⁸ Local milieu which implied exchanges within the area of a city or of a region, probably were determining factors for some particular discovery. So that generally speaking the eighteenth-century scholar was never isolated. Foucault underscored well “the difficulty to understand the network that links research as different as the taxonomic essays and the microscopical

observations”.⁷⁹ My belief is that an investigation into scientific exchanges shall allow to reconstruct networks of scholars concerned by microscopes, networks which local situation usually balances, and which are precisely one of the forms of the eighteenth- century microscopy. The shapes that these scientific exchanges took are mainly the scholar’s travel, education abroad, instrument trade, dispatch of living organisms, of engravings and drawings, translations, correspondences and publication --to which we could add... technological spying!⁸⁰ Such that against this isolationist approach, I will show the relevancy to work with systems of sources^g that allow coherency to emerge from multiple comparison of sources that quote each other.

77 Bracegirdle 1978a, 12.

78 See Kanz 1997, CTHS 1990, Frängsmyr et al. 1990, and the correspondences of Haller, Bonnet, Trembley, Réaumur, Needham, Spallanzani, Corti, Fontana, Hill, Ellis, Boerhaave, Musschenbroek, etc.

de Clercq 1991, Grmek 1991, Rousseau 1990, Manzini 1988, Dawson 1987, 198-242; M&R 1986, Di Pietro 1984-1995, Sonntag 1983, CRT 1943.

79 Foucault 1966, 139.

80 For cases of spying on scientific instruments during the second part of the century see Christensen 1993, and Perez & Pinault 1990 on Fougeroux de Bondaroy’s travel to Italy. On the reproduction of the methods used by Fraunhofer in the early nineteenth-century, see Jackson 1994, 569- 572.

1.2.1. The question of the microscopic illusion

By the 1960s, another trend appeared that influenced major parts of the later historiography. Bruno Zanobio had begun to show that important preachromatic

microscopists, such as Thomas Willis (1621-1675), John Hunter (1718-1783) and Paolo Mascagni (1755-1816) were “victims of the microscope”, mislead by their instruments, since eighteenth-century microscopes produced a “precise” kind of illusion Zanobio called the reticular-filamentous image. With a special technique and modern

microscopes, Zanobio created anew an analogous kind of reticular-filamentous image similar to the one drawn, in some of their plates, by previous micro-anatomists. The historical point is that the anatomists credited these images with a structural meaning Zanobio had denied any scientific value, because of their modern lack of meaning, and artifactual origin. This experimental-historical study influenced the Italian

historiography of microscopy, by providing it a procedure helping to reconstruct the factors producing illusion. The illusory microscopy, --as it was named among Italian historians-- produced by “bad microscopes”, was thus viewed as a factor adduced to explain the decline of microscopy: “A still incomplete knowledge of optical physics, and defective instruments produced erroneous microscopical observations that could only be corrected much later. And one really understands why, at the end of the eighteenth-century, scientific microscopy could not avoid to expire into a dead-end of which it would only be removed from with the advances on the lenses theory and the improvement of optical instruments”.⁸¹

Considered by Zanobio as a kind of research programme to put into general use for the history of microscopy,⁸² the thesis was actually echoed in many trends, because it eventually supplied historians with “technological proofs” demonstrating that preachromatic microscopes generously yielded artifacts. Luigi Belloni, for instances

81 Zanobio 1961, 593.

82 Zanobio 1971, 38-39.

considered Zanobio’s thesis a leading advance in the history of microscopy.⁸³ The illusory microscopy found many echoes and was applied to the explanation of particular phenomena, such as the globular illusion. Many microscopists, we are told, drew

globular images of animalcules of the infusions and of anatomical sections. Rupert S.

Hall considered globular theories such as Buffon’s, to be the product of the spherical aberration caused by the instrument.⁸⁴ Such a thesis has been developed by Philip Sloan who argued that the microscope Needham lent to Buffon was a Wilson simple

microscope.⁸⁵ Shirley Roe applied as well this logic in considering that for his embryological description of the development of the chicken embryo, “Wolff’s

‘globules’ were most likely optical artifacts”.⁸⁶ The same kind of explanation was recently put forward by Ghesquier about Galès’ determination of the Acarus scabiei in 1816.⁸⁷ In one way or another, eighteenth-century scholars were then almost always regarded as “victims of the microscope”, an expression coined by Zanobio thanks to his anachronistic inquiry.

What does such an investigation mean? There are some methodological criticisms to direct at Zanobio’s work. It is based on five images taken from five books printed between 1680 and 1820, and this should act as a causal explanation accounting for the eighteenth-century failure of microscopy... But Zanobio himself selected his images among hundreds of other images, which do not present the same defect. There is, as well, a flagrant contradiction between the magnification used by Zanobio to obtain his photographic image (x700!) and the average in magnification of eighteenth-century microscopes as was found by Bradbury and Bracegirdle, which is about x50-x60.

Moreover, Zanobio did not imagine other hypothesis to explain the reticular-

filamentous image, such as the possibility that they came from a specific technique used by drawers and engravers to fill up some spaces in a plate. We could perhaps find the

83 Belloni 1961, 1962, 65-68.

84 Hall 1969, 186.

85 Sloan 1992, 424-425. For a reconsideration of that thesis, see Stefani 2000, and chapter 6.

86 Roe 1981, 179. See also Roe 1981, 85-86.

87 Ghesquier 1999, 50.