¹ Fourteen instruments can be found in the collection of the Deutsches Museum, Munich, eleven at the Universiteitsmuseum Utrecht, sixteen at the Museum for the History of Science in Oxford and as many as forty-two at the Science Museum, London. I am indebted to Klaus Staubermann, who made the solar microscopes in the Utrecht collection accessible to me; the information regarding the solar microscopes kept in London and Oxford can be found in the Online Register of Scientific Instruments (http://www.isin.org/ressrch.asp?All=solar_microscope, accessed 27 October 2004).

² J. S. T. Gehler, Physikalisches Wörterbuch, 6 vols., 1787–96, iv, 100. As this quotation indicates, there also exist solar microscopes for opaque objects developed towards the end of the 1770s. These devices did not become as popular as the simple ones, however, and will not be discussed in detail here.

³ The scioptric ball can be described as a wooden ball placed in a wooden frame. The frame is placed in the shutter of the window. The instrument could be used for the projection (and observation) of the sun. The images can be seen at a point in the room depending on the position of the sun in the sky. A telescope or a microscope could be attached to the wooden ball and observation of projected microscopic specimens became possible. The scioptric ball has been described as a forerunner of the solar microscope. M. Fournier, Early Microscopes: A Descriptive Catalogue, Leiden, 2003; E. H. Schmitz, Handbuch zur Geschichte der Optik: Ergänzungsband II Teil A: Das Mikroskop, Bonn, 1989, 343 ff.

⁴ R. D. Altick, The Shows of London, Cambridge, MA and London, 1978; Hankins, T. L., ‘How the magic lantern lost its magic’, Optics & Photonics News (2003), 14, 34–40CrossRefGoogle Scholar.

⁵ F. Terpak, ‘Objects and context’, in Devices of Wonder: From the World in a Box to Images on a Screen (ed. B. M. Stafford and F. Terpak), Los Angeles, 2001, 143–364; D. Rossell, ‘Die Laterna Magica’, in Ich sehe was, was du nicht siehst! Sehmaschinen und Bilderwelten: Die Sammlung Werner Nekes (ed. B. v. Dewitz and W. Nekes), Göttingen, 2002, 134–46. This description can be traced back to J. L. Steiner's German translation of Baker's monograph: H. Baker, Das zum Gebrauch leicht gemachte Microscopium, Zurich, 1756.

⁶ S. Bradbury, The Evolution of the Microscope, Oxford, 1967, 153.

⁷ M. Fournier, op. cit. (3), 161.

⁸ H. Baker, The Microscope Made Easy, 5th edn, London, 1769 (reprinted Lincolnwood, 1987), 23 ff.

⁹ E. Nairne, The Description of a Single Microscope; And of an Apparatus Applicable to the same, in order to make it a Solar Microscope, which will equally serve for a Camera Obscura, and also for viewing Prints in Perspective, Greatly Improved for those Uses, London, n.d., 4.

¹⁰ Schaffer, S., ‘Natural philosophy and public spectacle in the eighteenth century’, History of Science (1983), 21, 1–43CrossRefGoogle ScholarPubMed; G. V. Sutton, Science for a Polite Society: Gender, Culture, and the Demonstration of Enlightenment, Boulder, 1995; O. Hochadel, Öffentliche Wissenschaft: Elektrizität in der deutschen Aufklärung, Göttingen, 2003; M. R. Lynn, Popular Science and Public Opinion in Eighteenth-Century France, Manchester, 2006.

¹¹ J. Priestley, The History and Present State of Discoveries relating to Vision, Light, and Colours, London, 1772, 742.

¹² An almost identical formulation can be found in Baker, op. cit. (8), 22; a comparable formulation is still found in Gehler, op. cit. (2), 100.

¹³ Goring, 1827, quoted in Bradbury, op. cit. (6), 159. Goring's statement can serve as an example for the strategies described by Wilson: ‘The feminization of the microscope assisted in reducing the prestige of an instrument of interest to and usable by ladies’; C. Wilson, The Invisible World: Early Modern Philosophy and the Invention of the Microscope, Princeton, 1995, 228. Like Goring, Marbach and Cornelius ‘also remark that the solar microscope is not useful for scientific investigations and serves more for entertainment’. O. Marbach and C. S. Cornelius, Physikalisches Lexikon, 2nd edn, 6 vols., Leipzig, 1856, iv, 1070. A remarkable detail in this respect lies in a short episode from the 1840s. Shortly after the introduction of photography, pictures of microscopic specimens were taken using solar microscopes that focused the image onto the photographic emulsion (see P. Harting, Das Mikroskop (tr. F. Theile), Braunschweig, 1859, 822 ff.).

¹⁴ Several historians have described eighteenth-century microscopes as toys. For a well-founded criticism of these interpretations see M. J. Ratcliff, ‘Europe and the Microscope in the Enlightenment’, Ph.D. dissertation, University College London, 2001, 6 ff.

¹⁵ The replication method is an attempt to analyse historical experimental practice that has been applied systematically by members of the Oldenburg group for more than two decades. In simple terms, this method can be described in three stages: reconstruction of the apparatus, redoing experiments and contextualization of the experience gained in the first two stages. For a methodological discussion see P. Heering, Das Grundgesetz der Elektrostatik, Wiesbaden, 1998; and C. Sichau, Die Viskositätsexperimente von J. C. Maxwell und O. E. Meyer: Eine wissenschaftshistorische Studie über die Entstehung, Messung und Verwendung einer physikalischen Größe, Berlin, 2002. Case studies by the Oldenburg group can be found at http://www.uni-oldenburg.de/histodid/22102.html. Though this method has been programmatic for the Oldenburg group's research, several earlier scholars used practical experience in their analyses, most notably on Galileo: Settle, T., ‘An experiment in the history of science’, Science (1961), 133, 19–23CrossRefGoogle ScholarPubMed, Naylor, R., ‘The role of experiment in Galileo's early work on the law of fall’, Annals of Science (1980), 37, 363–78CrossRefGoogle Scholar. There have also been previous attempts to use practical experience to analyse eighteenth-century microscopy: Belloni, L., ‘The repetition of experiments and observations: its value in studying the history of medicine (and science)’, Journal of the History of Medicine and Allied Sciences (1970), 25, 158–67CrossRefGoogle Scholar; R. G. Mazzolini, The Iris in Eighteenth-Century Physiology (1980); B. J. Ford, Single Lens: The Story of the Simple Microscope, New York, 1985. With respect to the latter works in particular, it seems important to stress that the motivation for using the replication method is to develop an understanding of the practice, not to check the historical results.

¹⁶ Heering, P., ‘To see or not to see. Jean Paul Marats öffentliche Experimente und ihre Analyse mit der Replikationsmethode’, NTM (2005), 13, 17–32CrossRefGoogle Scholar.

¹⁷ The Deutsches Museum in fact possesses two incomplete devices by Junker. One device lacked the tube, the microscope and the specimens, but these parts were extant for the other instrument, which lacked the ground plate and the condensing lens, so it seemed possible to combine these devices as shown on the image. But the cardboard tube did not fit into the ground plate. A new one had to be made by the museum's workshop.

¹⁸ During cleaning in the restoration workshop, no evidence was found that the instruments had been altered or the lenses changed.

¹⁹ ‘Most preparations made until the end of the eighteenth century were sliders, an ivory or bone strip with several openings, each containing two discs of mica held in place with a brass circlip, and the object mounted between them’. Bracegirdle, B., ‘Looking again at old microscope slides’, Endeavour (1994), new series, 18, 109–14, 109CrossRefGoogle Scholar.

²⁰ This procedure matches the description found in some historical accounts, such as J. Spengler, Optik, Catoptrik und Dioptrik, Augsburg, 1775, 192 ff.

²¹ Among those who attended the projections in the darkened chamber were several members of the Research Institute of the Deutsches Museum, including Michael Eckert, Alexander Gall, Ulf Hashagen, Cheryce Kramer, Christian Sichau, Jürgen Teichmann and Helmuth Trischler, as well as people from other institutions such as Terje Brundtland (Oxford), Elizabeth Cavicchi (Boston) and Peter Plassmeyer (Dresden).

²² I am indebted to Elizabeth Cavicchi who has agreed to give a report, to be published in this journal, on her experiences as a visitor to one of the demonstrations I made. I should be clear, however, that her analysis might differ from mine as both papers were written independently; she was a viewer whilst I was demonstrator. Probably more important is the fact that she attended only one demonstration, whilst I made some twenty demonstrations for different audiences and significantly more projection sessions without any audience.

²³ In interviews and questionnaires only very open questions were used, such as ‘What do you expect to see in the demonstrations?’ (in the pre-test) or ‘What are your impressions of the projections?’ (in the post-test). In keeping these questions as open as possible, it was intended that answers be as little influenced as possible.

²⁴ This presentation was made at the beginning of my project; consequently, I had not conducted any projections. It was not surprising to me that everyone stressed the high quality and brightness of the images. This was also my own impression when I projected the first images. However, this kind of feedback is important for my study since it makes clear that such an evaluation results not from a personal bias but can be seen as a more collective experience.

²⁵ The diameter of the light circle is (in Figures 5–9) about 1.60 metres. The exposure time was about 8 seconds. This time was necessary to get a result comparable to what could be seen in the darkened room. All photos were transformed into greyscale; no other modifications were made.

²⁶ The flea is mentioned regularly as one of the specimens that were provided with the instrument. This is confirmed by the few surviving specimen lists, such as E. Nairne, Description and Use of the Compound Microscope by Nairne, n.d., and also the list accompanying a solar microscope in the Universiteitsmuseum Utrecht (Sign. UM 143).

²⁷ There are still a few signs of artefacts in the image due to dust on the lenses or to some minor errors on the mirror.

²⁸ This also matches Bracegirdle's observation that ‘throughout the various editions of Baker, from the first in 1743 to the last in 1785, there is no difference in the advice on mounting’. L. B. Bracegirdle, A History of Microtechnique, Ithaca, NY, 1978, 18.

²⁹ Matters seem different in historians' accounts of modern ‘microscopes’ such as the scanning tunnelling microscope or the electron microscope. See, for example, F. Müller, ‘Zwischen Bilderbuch und Messgerät: Der elektronenoptische Blick auf die Realstruktur von Festkörpern’, in Konstruierte Sichtbarkeiten: Wissenschafts- und Technikbilder seit der frühen Neuzeit (ed. M. Hessler), München, 2006, 75–98. The underestimation or even neglect of peripheral parts of a complex experimental set-up has already been pointed out by Sichau in his analysis of the Joule–Thomson effect: C. Sichau, ‘Industry and industrial relations within the laboratory: the material conditions of Joule–Thomson experiments’, in Proceedings of the XXth International Congress of History of Science 7: Technology and Engineering (ed. M. Lette and M. Oris), Turnhout, 2000, 49–59.

³⁰ Again, these assessments are based not only on my own experiences but also on feedback from visitors to my darkened room.

³¹ Anon., ‘Nachricht von einem brauchbaren und wohlfeilen Sonnen-Mikroskop’, Magazin für das Neueste aus der Physik und Naturgeschichte (1791), 7, 84–7, 87Google Scholar.

³² See J. F. Häseler, Betrachtungen, über die Verbesserung der Zauberlaterne, des Sonnenmikroscops, und der Camera Obscura nach der Theorie des Herrn Leonhard Euler, Holzminden, 1779, 6; and W. F. v. Gleichen, genannt Rußworm, Auserlesene mikroskopische Entdeckungen bey den Pflanzen, Blumen und Blüthen, Insekten und anderen Merkwürdigkeiten, Nürnberg, 1777, 150. The criticism in the latter text could also be interpreted as a consequence of a dispute between Gleichen and Ledermüller, who strongly advocated solar microscopes. On this dispute see E. Reicke (ed.), Neues aus der Zopfzeit, Leipzig, 1923. An entirely different reason for criticizing the quality of the images produced with the solar microscope was given by Georg Paul Nussbiegel, who produced the coloured plates of Ledermüller's first volume on ‘Augen- und Gemüthsergötzungen’. In advertising this volume he pointed out that he had prepared these plates without using the solar microscope because thus he had been able to avoid artificial colouring. See Nussbiegel, G. P., ‘Nachricht von einem physikalischen Werke, so unter dem Titel microscopische Augen- und Gemüthsergötzungen, mit dem 1759sten Jahre herauskommen wird’, Hamburgisches Magazin, oder gesammlete Schriften, zum Unterricht und Vergnügen (1759), 22, 537–44Google Scholar.

³³ This description is somewhat oversimplified. In most situations the audience did not discuss the first images I showed but simply looked at them and were silent. Thus, in these cases, I had to start the discussion; however, after I had shown some images the viewers discussed the new images without my intervention. Nevertheless, I was still involved in the discussion as I was the only person who knew what the images showed and thus had some authority in cases where controversial interpretations of the images were expressed. The silence at the start of the demonstration might be due to the unusual situation. Strikingly, the largest group that was shown the images (about ten people from the museum's workshops) started to discuss the images immediately.

³⁴ The difficulty of producing an image of the specimen with a common microscope has frequently been discussed, e.g. I. Hacking, Representing and Intervening: Introductory Topics in the Philosophy of Natural Science, Cambridge, 1983.

³⁵ L. Fleck, ‘To look, to see, to know’ (1947), in Cognition and Fact: Materials on Ludwik Fleck (ed. R. S. Cohen and T. Schnelle), Dordrecht, 1986, 129–51.

³⁶ Walters, A. N., ‘Conversation pieces: science and politeness in eighteenth-century England’, History of Science (1997), 35, 123–54, 141CrossRefGoogle Scholar.

³⁷ Walters, op. cit. (36), 126.

³⁸ Walters, op. cit. (36), 141. A similar argument is made by B. M. Stafford, Body Criticism: Imaging the Unseen in Enlightenment Art and Medicine, Cambridge, MA, 1991, 360.

³⁹ The (potential) social role of microscopes in the eighteenth century has also been discussed by Ratcliff, who goes beyond Walters's description in distinguishing between the ‘democratic microscope’ and the ‘elitist microscope’ (Ratcliff, op. cit. (14)). This differentiation corresponds to several aspects I consider important in the contrast between solar microscopes and common microscopes.

⁴⁰ On the plates and their role in Hooke's Micrographia see J. T. Harwood: ‘Rhetoric and graphics in Micrographia’, in Robert Hooke: New Studies (ed. M. Hunter and S. Schaffer), Woodbridge, 1989, 119–47. On the role of the plates for learning how to see with the microscope see also Fischel, A., ‘Sehen, Darstellen, Beschreiben: Mikroskopische Beobachtungen in den Kupferstichen der Micrographia’, kunsttexte.de, Sektion BildWissenTechnik (2002), 1, 1–10Google Scholar.

⁴¹ Schickore, J., ‘Ever-present impediments: exploring instruments and methods of microscopy’, Perspectives on Science (2001), 9, 126–46, 128CrossRefGoogle Scholar.

⁴² G. Adams, Micrographia Illustrata, or, The Knowledge of the Microscope Explain'd: Together with an Account of a New Invented Universal, Single or Double, Microscope, Either of which is capable of bein [sic] applied to an Improv'd Solar Apparatus, 2nd edn, London, 1747, 11.

⁴³ In this respect, the resemblance between the observational situation of the solar microscope and that of the well-established camera obscura may also have played a role. According to Crary's analysis of the camera obscura, in the eighteenth century this device was ‘synonymous with the production of truth and with an observer positioned to see truthfully’. J. Crary, Techniques of the Observer: On Vision and Modernity in the Nineteenth Century, Cambridge, MA, 1990, 32. Yet the use of the camera obscura was limited to the macroscopic world while the solar microscope can be seen as its equivalent for the microscopic world. But to avoid misunderstandings it is clear that some researchers also used the solar microscope individualistically to generate new knowledge. An example is A. W. Roth, who worked on water organisms and employed the solar microscope in his research. A. W. Roth, Bemerkungen über das Studium der cryptogamischen Wassergewächse, Hannover, 1797 (I am indebted to B. Grauwinkel who drew my attention to this researcher).

⁴⁴ For an analysis of this process, in the particular context of the French Academy of Sciences, see P. Heering, Experimentierstile in der zweiten Hälfte des 18. Jahrhunderts, Habilitationsschrift, Hamburg, 2006. For a discussion of an episode that can be seen as one of the starting points of the development of a new style of experimentation that became dominant in the nineteenth century see Heering, P., ‘Regular twists: replicating Coulomb's wire-torsion experiments’, Physics in Perspective (2006), 8, 52–63CrossRefGoogle Scholar.

⁴⁵ B. Stafford, ‘Revealing technologies/magical domains’, in Devices of Wonder: From the World in a Box to Images on a Screen (ed. B. M. Stafford and F. Terpak), Los Angeles, 2001, 1–142, 81 ff.

⁴⁶ M. Seeberger, ‘Camera obscura und Sonnenmikroskop’, in G. F. Brander 1713–1783: Wissenschaftliche Instrumente aus seiner Werkstatt (ed. A. Brachner), München, 1983, 229–40, 231.

⁴⁷ For the following discussion of perception with the common microscope, U. Stadler's discussion of Jonathan Swift's Gulliver's Travels has been very helpful. U. Stadler, Der technisierte Blick: Optische Instrumente und der Status von Literatur. Ein kulturhistorisches Museum, Würzburg, 2003.

⁴⁸ G. F. Brander, Beschreibung zweyer zusammengesetzten Mikroscope, Augsburg, 1769. A comparable description of microscopy can be found in F. W. Dieck, Deutliche Anweisung, Vergrösserungsgläser auf eine leichte Art zu schleifen wie auch einfache und zusammengesetzte Sonnenmikroskope zu verfertigen', Hamburg, 1793.

⁴⁹ In this respect, the microscope can be compared to the telescope, an instrument that mediates between the earthly observer and celestial objects but at the same time separates them. Several authors who discussed microscopes also put telescopes in this context: J. E. B. Wiedeburg, Ob eine so große Verbesserung der FernRöhren zu hoffen sey, daß man dadurch Einwohner in den Planeten, wenn es dergleichen gäbe, deutlich genug erkennen könne, Jena, 1762. According to Böhme, the connection between the microscope and the telescope was already made by Hooke: H. Böhme, ‘Die Metaphysik der Erscheinungen: Teleskop und Mikroskop bei Goethe, Leeuwenhoek und Hooke’, in Kunstkammer – Laboratorium – Bühne: Schauplätze des Wissens im 17. Jahrhundert (ed. H. Schramm, L. Schwarte and J. Lazardzig), Berlin, 2003, 359–96.

⁵⁰ Anon., ‘Versuch, über die Vortheile des Sonnenmikroskops’, Neues Hamburgisches Magazin (1781), 119, 457–79, 460Google Scholar.

⁵¹ This kind of perception is not limited to accounts of actual demonstrations with solar microscopes. It can also be found in E. T. A. Hoffmann's novel Meister Floh. Here, two magicians take the image of the princess Gamaheh from the wall onto which it has been projected with a solar microscope and revive the princess in so doing.

⁵² H. v. Pückler Muskau, Tour in England, Ireland, and France, in the years 1826, 1827, 1828 & 1829 … in a series of letters, London, 1832, 116 ff., quoted in Seibold-Bultmann, U., ‘Monster soup: the microscope and Victorian fantasy’, Interdisciplinary Science Reviews (2000), 25, 211–19, 211CrossRefGoogle Scholar.

⁵³ Hoffmann's novel has a scene in which the audience flees from the projection chamber that is filled with menacing creatures that resemble those described by Pückler Muskau. Since Hoffmann's novel was published in 1822, it may have influenced Pückler Muskau's description.

⁵⁴ W. F. Freiherr von Gleichen, genannt Rußworm, op. cit. (32), 154.

⁵⁵ Brander op. cit. (48), 18. Brander's description was intended for experiments with the common microscope but could also be used with the solar microscope.

⁵⁶ M. F. Ledermüller, Nachlese seiner Mikroskopischen Gemüths- und Augen-Ergötzung, Nürnberg, 1762, 45.

⁵⁷ [?] Coulembier, Sonnen-Mikroskop oder die neu entdeckten Wunder der Natur, 2nd edn, Karlsruhe, 1835, 16.

⁵⁸ This does not mean that popularization (or projecting microscopes) played no role in the nineteenth century; on the contrary. This can be illustrated by examples such as the episode of the solar microscope in photography (see note 13 above) or the popularity of lantern projection shows. T. L. Hankins and R. J. Silverman, Instruments and the Imagination, Princeton, NJ, 1995; K. Staubermann, ‘The nineteenth-century astronomical lantern slide’, in East and West: The Common European Heritage (ed. E. Wyka, M. Kluza and A. K. Zawada), Krakow, 2006, 121–8.