Antoni Van Leeuwenhoek, His Images and Draughtsmen

Antoni van Leeuwenhoek, His Images and Draughtsmen

Sietske Fransen Bibliotheca Hertziana—Max Planck Institute for Art History

This article provides, for the first time, an overview of all images (drawings and prints) sent by the Dutch microscopist Antoni van Leeuwenhoek (1632– 1723) to the Royal Society during their fifty-year long correspondence. Anal- yses of the images and close reading of the letters have led to an identification of three periods in which Leeuwenhoek worked together with artists. The first period (1673–1689) is characterized by the work of several draughtsmen as well as Leeuwenhoek’s own improving attempts to depict his observations. In the second period (1692–1712) Leeuwenhoek worked together with one unknown draughtsman, while the work in the third period (1713–1723) can now be attributed to the young draughtsman Willem vander Wilt. This article also shows how Leeuwenhoek did not only rely on draughtsmen for the depiction of his own observations, but rather, how he worked together with them in his workshop to observe, confirm, and witness microscopic experiments, replicating the collaborative working methods of the Royal Society in Delft.

1. Introduction This article provides for the ﬁrst time an overview of the drawings and prints Antoni van Leeuwenhoek (1632–1723) sent to the Royal Society and its Fellows, and discusses how these images were produced by Leeuwenhoek and his draughtsmen. By comparison and analysis of the way Leeuwenhoek described the images, the making of the images, and the ways of seeing,

This work was supported by the Arts and Humanities Research Council (grant no. AH/ M001938/1). My thanks go to Douglas Anderson and Huib Zuidervaart for their invaluable comments on an earlier version of this article; to the editor Puck Fletcher, making this a readable text; to the wonderful staff of the Royal Society Library and Archives for all their help; and to Felicity Henderson, Sachiko Kusukawa, Alexander Marr, and Katherine Reinhart for their many comments and support in the process of writing this article.

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depicting, and constructing visual evidence, I hope to contribute to a better understanding of Leeuwenhoek’spracticeof“doing science.” It will become clear that he was fully aware of the impact of visual evidence needed to prove his observations to his correspondents in other parts of Europe. He was also fully aware of the role of the draughtsman, who was much more than an intermediary, invisible workman. Instead, Leeuwenhoek used his draughtsmen as collaborators and witnesses (although without crediting them by name) in his business of observing and communicating the smallest objects the human eye had seen so far. On 6 August 1687, Antoni van Leeuwenhoek (fig. 1) wrote the following to the Royal Society: People have come to talk to me, and sing the praises, of a certain little Book, dealing with Microscope Observations, which were uncommonly magnified, which Booklet was for sale at the last Frankfort Trade Fair. I was very eager to have that, as I hoped to get some enlightenment from it: But no sooner had I received that Book, called Micrographia Nova, published by Mr. Joh. Francisco Griendelio, than I saw that it was to me quite worthless: for the small creatures that, amongst others, are depicted therein, as Louse, Flea, Ant, etc., were indeed big, but drawn very imperfectly and deformed. Now whether this is due to the lack of good Magnifying glasses, or whether it is the Draughtsman’s fault, is not known to me. (AdB, 7:36–37)1 By the time Leeuwenhoek wrote this letter, he had been confidently corresponding with the Fellows about microscopy for fourteen years.2 The Dutch cloth-merchant from Delft was an autodidact when it came to scientific investigation, but he sustained an intense correspondence with the Royal Society and its individual Fellows from 1673 until his death. In this period he wrote more letters to the Royal Society and its Fellows (223 in total) than any other correspondent.3 Since most of these letters (ca. 200) still survive in the archives of the Royal Society, his writings and his images are a valuable source for historians interested in the history of microscopy

1. AdB, Letter 102 (6 August 1687). All English translations of Leeuwenhoek letters are taken from this edition, with small emendations by me, unless otherwise stated. The book referred to in the quotation is Griendel’s Micrographia nova (1687). 2. On Antoni van Leeuwenhoek, see the comprehensive, but slightly old-fashioned biography by Dobell (1932), and the rich and well-researched website by Douglas Anderson, without whose work this article could not have been written: https://lensonleeuwenhoek.net (last accessed 28 February 2019). 3. For a more general understanding of the visual culture in the early Royal Society see the article by Kusukawa (2019) in this special issue.

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Figure 1. Jan Verkolje, Portrait of Antoni van Leeuwenhoek, 1686. Mezzotint. 296 × 227 mm. London, Royal Society archives. (Photo © The Royal Society).

and microbiology in the seventeenth century, as well as the history of scientific correspondence, and the use of text and image. The quotation above shows how well informed Leeuwenhoek was about new publications on his favorite topic. The first thing Leeuwenhoek did after receiving the book was to look at the images, and his judgment was brutal. Although he had been looking forward to learning something new, the images, despite their size, were “drawn very imperfectly and deformed.” Leeuwenhoek, however, did not blame Johann Frantz Griendel (ca. 1631–1687) directly for this, as Leeuwenhoek was the first to

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acknowledge that the drawing of microscopic observations was a complex process. He acknowledged that anyone using microscopes was dependent on the quality of the instruments (the microscopes or magnifying glasses) through which both the primary researcher and the draughtsman had to observe the object, and that subsequently, an author/researcher was also dependent on the craftsmanship of the draughtsman for the final result. These were matters Leeuwenhoek had been dealing with from the start of his correspondence with the Royal Society. In April 1673, at the age of forty, Leeuwenhoek was introduced to the Royal Society through a letter by his fellow citizen, the physician Regnier de Graaf (1641–1673). The Secretary at the time, the German-born Henry Oldenburg (ca. 1619– 1677), responded with approval and immediately published the text of Leeuwenhoek’s first observations, on the sting of a bee, in his journal Phil- osophical Transactions (Leeuwenhoek 1673a). However, from further correspondence we can see that Leeuwenhoek had not sent any images with his first letter, as three issues later, Oldenburg wrote: This Curious observer [i.e., Leeuwenhoek], having been desired by the Publisher [i.e., Oldenburg], since his first Communications, already printed in these Papers, that for further satisfaction he would please to transmit the Figures of what he had so well observed, and he having not only very obligingly complied with that desire, but also added New Observations; we thought ourselves bound to do him right in publishing both the Figures of his former Communications, and his Additions thereunto. (Leeuwenhoek 1673b) Leeuwenhoek continued this practice of sending figures with his observations to the Royal Society. In the case of the imperfectly drawn images in Griendel’sbook, Leeuwenhoek responded visually. In his letter to the Royal Society, Leeuwenhoek had a copy made of the faulty depiction of the louse’s leg from Griendel’s book, and he compared it to a drawing he had sent to the Royal Society twelve years earlier.4 I have thought fit to get only two legs copied, of the Louse, that was in that Booklet, to indicate the deformity of the same. Fig. 9. AB. and CD. [see fig. 2] are the two legs of the Louse that are found drawn in the aforesaid Micrographia Pag. 14, and which legs were indicated there by I. and C. I have seen several Lice as drawn through the Microscope, but they all differ from my own Observations. About

4. The original handwritten letter is lost, but Leeuwenhoek’s printed copy remains. See AdB, Letter 102 (6 August 1687).

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Figure 2. Unknown engraver, Legs of a louse as observed by Griendel (ﬁg. 9) and Leeuwenhoek (ﬁg. 10), in Antoni van Leeuwenhoek’s, Vervolg der Brieven, between pp. 66–7, 1687. Engraving. 50 × 140 mm. Leiden, Rijksmuseum Boerhaave (detail). (Photo Rijksmuseum Boerhaave, Leiden).

twelve years ago I sent Your Honour the drawing of a Louse’sleg [see fig. 3], in order that you might see the perfect shape of such a tiny creature. And as I have also found another drawing of it, I have caused this to be printed here as well [see fig: 10 in Fig. 2], in order that one may see the structure of the Louse’s leg, as I showed it to the Draughtsman, and which he has drawn from life [na’t leven], against the structure such as they have depicted it in Germany (AdB,7:36–39).5 Again, Leeuwenhoek is giving his contemporary readers a lot of information at once. He had images from a book copied out by a draughtsman (teikenaar) so that he could publish them in comparison to his own drawings. And although he had previously sent his drawing to the Royal Society (see fig. 3), he must have had copies made of the drawing, from which an engraver was able to make a new image for print. In the meantime, he acknowledged that he was once more well aware of his contemporaries who researched and published on similar topics, but that their various depictions all differed from his own observations. In this article I discuss Antoni van Leeuwenhoek’s approach to images in his correspondence: his handwritten letters as well as those he published in printed collections. Encouraged initially by Henry Oldenburg, Leeuwenhoek sent about 1000 images to London throughout his fifty-year correspondence

5. AdB, Letter 102 (6 August 1687).

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Figure 3. Unknown draughtsman for Antoni van Leeuwenhoek, A Louse’s leg, 25 March 1675. Graphite and ink on paper. 60 × 55 mm. London, Royal Society archives, EL/L1/13 (detail). (Photo © The Royal Society).

with the Royal Society. A little more than half of the letters (126) sent to the Royal Society originally contained images in the form of drawings, printed engravings, and etchings.6 Currently eighty of the original letters by Leeuwenhoek still contain images—the rest of the images have gone missing over the past 300 years. In what follows, I will discuss brieﬂy the way in which Leeuwenhoek was able to observe objects with a microscope, and I will then describe the drawings and prints in Leeuwenhoek’s correspondence with the Royal Society. My study of the drawings and prints has led me to newly attribute a signiﬁcant number of drawings to Leeuwenhoek himself. It has provided me with evidence for the division of all the drawings and prints in the Leeuwenhoek correspondence at the Royal Society into three subsequent periods in which Leeuwenhoek worked with different draughtsmen. A comparison with contemporary source material has made it possible to identify the artist Willem vander Wilt, who was already associated with Leeuwenhoek, as the draughtsman of the third period.

6. We know this due to the references to images in the letters, even if the images no longer exist.

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2. How to See As Leeuwenhoek mentioned in his commentary on Griendel’s book, faulty depictions of microscopic observations can have two main causes: the skill (or the lack thereof) of the draughtsman, or the quality of the microscope used. Leeuwenhoek himself was an expert on the latter, and produced many single-lens microscopes himself throughout his life (ﬁg. 4). During his lifetime he was already famous for his microscopes, the production

Figure 4. Antoni van Leeuwenhoek, Microscope, ca. 1670–1710. Brass. 70 × 20 × 25 mm. Leiden, Rijksmuseum Boerhaave. (Photo Rijksmuseum Boerhaave, Leiden).

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method of which he kept strictly secret. He understood the various powers of magnification of lenses, and was therefore aware of the things that could and could not be seen depending on the instruments and lighting conditions.7 However, although good instruments and draughtsmen might have been necessary to depict something, one needed even more to see. To be able to see, the observer also needs to be able to use the microscopes correctly, to prepare specimens so that they can be observed, and to make judgments as to what one is seeing and what is worth drawing and communicating. As Karin Leonhard (2017) and Simon Rebohm (2017) have shown recently, Leeuwenhoek was careful to lay out all of these steps. He would prepare his experiments meticulously, which we know as he regularly described them in detail. In his letters we find references to the way he cut small, thin slices of human and animal skin, hair, or optical nerves; thin enough so that light could pass through them to enable him to observe the specimens. Less straightforward is how to observe fluids. But early on in his correspondence, Leeuwenhoek explained how he observed fluids with specially prepared glass tubes that he stuck to the pin of his microscope. After explaining this observation method, he described how he extracted brain fluid from a cow, poison from a scorpion, or blood from himself. Once the preparations were made, the next important step was to mount the specimen onto the pin of the microscope and to make sure the object was in focus. This was not an easy task with the type of microscopes Leeuwenhoek used, and could only be done be tweaking the small screws on the microscope that would change the distance between the object and the lens ever so slightly. The next step was to produce enough light to see the object, something that could be sorted out relatively easily since the microscopes were small and could be hand-held. As Leeuwenhoek explained, to get the best results, “the instrument may be held within doors and in the shade, yet held to the free Air, as if with a Telescope you would look upon the Stars in the Firmament” (AdB,1:114–15).8 However, moving the instrument also risked moving the specimen, taking it out of focus again.9

7. There is a vast literature on Leeuwenhoek’s microscopes. For the most recent research, see Zuidervaart and Anderson (2016), and new discoveries about Leeuwenhoek’slensmaking practices by Tiemen Cocquyt (2016) and Cocquyt, Bolt, and Korey (2018). On the use of optical instruments in seventeenth-century Delft, see Zuidervaart and Rijks (2015). For broader context on seventeenth-century microscopy, see Ruestow (1996), Fournier (1996), and Ratcliff (2009). 8. AdB, Letter 8 (1 June 1674). 9. Other solutions for producing enough light to observe specimens were already described by Robert Hooke in his Micrographia (1665, d*v-er). See for more on Robert Hooke and visual culture, the article by Felicity Henderson in this issue (2019).

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As we shall see in the course of this article, Leeuwenhoek worked closely with draughtsmen who had to see exactly what he saw, so that they could draw “his” observations (Leonhard 2007). In many ways, Leeuwenhoek and his draughtsman were thus exercising “four-eyed sight,” creating images based on their collaborative observations, as discussed by Daston and Galison (2010, pp. 84–98). One way Leeuwenhoek dealt with the practicalities of the sensitivity of the instruments was to prepare one microscope per specimen, so that he did not have to change the specimen on the instrument. He referred to this practice early on in his correspondence when he wrote that “each figure has been seen and drawn through a particular magnifying glass,” meaning that every specimen was mounted on its own microscope (AdB, 1:42–43).10 Leeuwenhoek also had to match the magnification of his lenses and microscopes to what he was observing.11 Since every lens was slightly different due to the fact they were hand-made, they also all had different powers of magnifications, and different specimens required different strengths of magnification to do justice to the observed.

3. The Drawings Leeuwenhoek needed only one nudge from the Royal Society’s Secretary, Henry Oldenburg, to start preparing visual reports for his London-based audience. After the first exchange between Oldenburg and Leeuwenhoek, through their intermediary Regnier de Graaf, Leeuwenhoek started sending images with his letters on a regular basis. The first letter sent by Leeuwenhoek to the Royal Society has only survived in the English extracts printed in the Philosophical Transactions (Leeuwenhoek 1673a). Moreover, the images sent by Leeuwenhoek with his second letter are now extant only as engravings in the journal (Leeuwenhoek 1673b). The second letter (minus its images) is the first that survives in its original handwritten form and is from 15 August 1673. In this letter, Leeuwenhoek referred to the previous letter he wrote, and apologized for his “simple pen,” or plain writing style (AdB, 1:42–43).12 Leeuwenhoek apologized for not having been educated in languages and arts, only in trade, even though he likely did attend some years of Latin school as an adolescent (Seters 1982). He also mentioned the drawings he sent, with the comment that “as I am not a draughtsman myself, I have had them drawn for me” (AdB,

10. AdB, Letter 2 (15 August 1673): “oock is ijder ﬁgure door een bijsonder vergroot glas gesien, en geteijckent.” 11. Of the eleven genuine Leeuwenhoek microscopes that are now recognized, the magni- ﬁcation varies between 70 and 150, with two exceptions that magnify 248 times and 267 times (Cocquyt 2016, p. 36; Zuylen 1981, p. 313; Zuidervaart and Anderson 2016, pp. 286–88). 12. AdB, Letter 2 (15 August 1673).

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1:42–43).13 Leeuwenhoek referred to his draughtsmen (teikenaars)in many of his letters, and this first mention and the regular descriptions of Leeuwenhoek’s collaboration with his draughtsmen have led historians of Leeuwenhoek to believe that most of the drawings in his letters now at the Royal Society were indeed made by those other than himself (Dobell 1932, pp. 342–45). However, close reading of the letters and analysis of the drawings show that about 82 figures amongst the letters were drawn by Leeuwenhoek himself.14 All of these drawings are from an early period of Leeuwenhoek’s correspondence with the Royal Society and demonstrate a remarkable improvement in drawing skills over time. This early period is characterized by the inclusion of many different hands, including Leeuwenhoek’sown. In the thirteen letters containing his own drawings, Leeuwenhoek often mentioned the fact that he drew them himself (see Table 1A). In the first three of these thirteen letters he does not talk about the drawing process at all. However, in these first few cases the drawings were all added to the margins of the letter itself and it is unlikely that Leeuwenhoek had someone draw on his actual letter. Furthermore, all the drawings that Leeuwenhoek mentioned as made by other artists were sent with his letters on separate pages. So it is reasonable to surmise that these anonymous drawings from the first three of these letters were made by Leeuwenhoek himself. In the first letter with drawings by Leeuwenhoek, he recounts his experiments with air pressure (AdB,1:40–61).15 The first drawing, in the same ink as the letter, depicts Leeuwenhoek’s hypothesis of how branches and leaves at the top of a tall tree receive water from the roots (fig. 5). Leeuwenhoek hypothesized, on the basis of his microscopic observations of sections of leaves, branches, roots, and wood from trees, that long, thin tube-like pas- sages, like CD in the drawing, form the route of water from root to top. The bottom left part of the drawing shows the pressure needed from EF to push the water all the way up to D. His theories led him to do further experiments with small glass tubes to better understand the workings of water and air, and the possibility of adding more pressure. Two of these experiments were depicted in the other two marginal drawings in this letter (figs. 6a and 6b).

13. Idem, p. 42: “ick heb deselve, also ick niet teijckenen kan, later uijtteijcken [sic].” 14. It is not always easy to determine how many figures a page with drawings contains, especially when they are not labeled. I have counted every figure separately unless they are organized as a group with one title, such as in Leeuwenhoek’s depictions of salt crystals from 11 February 1675 (AdB, Letter 16; Royal Society archives, EL/L1/11), see fig. 9. 15. AdB, Letter 2 (15 August 1673).

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Drawings and Hands in Period 1 (1673–1689) Date of Letter no. letter to Archive No. of Drawing Number in AdB RS reference ﬁgures Technique Draughtsman Comments

1 2 15 August EL/L1/1 3 pen and ink Leeuwenhoek Drawings are in the margins 1673 of the letter in the same ink as the writing. 2 8 1 June 1674 EL/L1/4 2 pen and ink Leeuwenhoek Drawings are in the margins of the letter in the same ink as the writing. 3 9 6 July 1674 EL/L1/5 2 pen and ink Leeuwenhoek Drawings are in the margins of the letter in the same ink as the writing. 4 16 11 February EL/L1/11 30 pen and ink Leeuwenhoek Leeuwenhoek mentioned in 1675 the letter he drew the images himself (AdB, 1:232). 5 26 9 October EL/L1/22 2 pen and ink Leeuwenhoek Leeuwenhoek mentioned in 1676 the letter he drew the images himself (AdB, 2:130). 6 39 31 May 1678 EL/L1/36 3 pen and ink Leeuwenhoek Leeuwenhoek mentioned in the letter he drew the images himself (AdB, 2:364–67). 7 47 20 May 1679 EL/L1/41 1 pen and ink Leeuwenhoek Drawings are in the margins of the letter in the same ink as the writing.

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Drawings and Hands in Period 1 (1673–1689) Date of Letter no. letter to Archive No. of Drawing Number in AdB RS reference ﬁgures Technique Draughtsman Comments

8 54 12 January EL/L1/49 19 pen and ink, and red Leeuwenhoek Leeuwenhoek mentioned in 1680 chalk, lighter and the letter he drew the images ﬁrmer application, himself (AdB, 3:150, 164–67). no shading 9 57 5 April 1680 EL/L1/52 1 red chalk, light Leeuwenhoek Leeuwenhoek mentioned in (Fig. 1) application, some the letter he drew the images shading himself (AdB, 3:202). 10 62 14 June 1680 EL/L1/57 3 pen and ink, Leeuwenhoek Leeuwenhoek mentioned red chalk in the letter he drew the images himself (AdB, 3:250). 11 66 4 November EL/L1/64 4 red chalk, with Leeuwenhoek Leeuwenhoek mentioned in 1681 some shading the letter he drew the images himself (AdB, 3:354). 12 67 3 March 1682 EL/L1/65 6 red chalk, with Leeuwenhoek Leeuwenhoek mentioned in some shading the letter he drew the images himself (AdB, 3:394). 13 85 13 July 1685 EL/L1/76 6 red chalk, thinly Leeuwenhoek Leeuwenhoek mentioned in applied the letter he drew the images himself (AdB, 5:224). Total drawings by 82 Antoni van Leeuwenhoek

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Drawings and Hands in Period 1 (1673–1689) Letter no. Date of Archive No. of Drawing Number in AdB letter to RS reference ﬁgures Technique Draughtsman Comments

Probably Leeuwenhoek’s drawings 1 65 12 November EL/L1/62 5 pen and ink, Leeuwenhoek? Drawings 3, 4, 5 in this 1680 (Figs. 1, 2, 5, 7, 8) red chalk letter are made by a draughtsman, but Leeuwenhoek doesn’t specify that these 5 drawings were made by someone else, while ﬁgures 5 and 8 are very similar to earlier drawings by Leeuwenhoek himself. 2 89 22 January LBO/11i/017 3 Red chalk, Leeuwenhoek? These drawings of salts are 1686 strongly applied similar to earlier drawing by Leeuwenhoek. Total drawings probably 8 by Antoni van Leewenhoek

Unknown Draughtsmen 1 13 4 December EL/L1/9 1 Hand-printed, ? This image was copied from a 1674 graphite red chalk drawing now in the British Library (Add MS 22953, f. 125). The hand of the BL drawing looks similar to that of draughtsman 1.

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2 17 26 March EL/L1/13 2 Hand-printed, ? These images are nature prints 1675 (Figs. 5, 6) black ink from oak leaves. 3 17 26 March EL/L1/13 4 Graphite, skillfully Unknown 1675 (Figs. 1–4) applied, with much draughtsman 1 use of shading and depth 4 21 22 February EL/L1/17 4 Graphite, black Unknown 1676 chalk, skillfully draughtsman 1 applied, with much use of shading and depth 5 43 25 April EL/L1/40 1 Multi-coloured Unknown 1679 chalk draughtsman 2 6 54 12 January EL/L1/49 4 Hand-printed, ? Leeuwenhoek mentioned that 1680 (Figs. 1–4) black chalk someone other then himself made these black chalk copies from his own red-chalk originals. 7 57 5 April 1680 EL/L1/52 1 Ink and grey wash, Unknown (Fig. 2) use of shading draughtsman 3

Downloaded from http://www.mitpressjournals.org/doi/pdf/10.1162/posc_a_00314 by guest on 26 September 2021 8 65 12 November EL/L1/62 3 Ink and body colour Unknown Very different drawing style 1680 (Figs. 3, 4, 6) draughtsman 4 than all other drawings. 9 93 10 June 1686 EL/L2/4 6 Ink and grey wash, Unknown There are 2 ﬁgures 5, counting (Figs. 2– 6) use of shading draughtsman 3 up to 6 by this draughtsman in total. 10 93 10 June 1686 EL/L2/4 24 Graphite and red Unknown chalk, skillfully draughtsman 1 applied, with much use of shading and depth 11 94 10 July 1686 EL/L2/6 2 Red and black Unknown chalk, strongly draughtsman 1 applied 12 114 1 April 1689 EL/L2/25 6 Red chalk, strongly Unknown applied draughtsman 1 Total drawings by 58 unknown draughtsmen

TOTAL DRAWINGS PERIOD 1 140

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In the next letter with images, Leeuwenhoek also drew glass tubes in the margins of his letter (AdB,1:90–115).16 In this he described how he made these tubes himself to be able to observe fluids with his microscope. With the tubes and the capillary effect of the very tiny tubes (“some […]notthickerthanamanshair”), Leeuwenhoek was able to observe for example blood and milk (AdB,1:96–97). As well as his drawings and explanations, he sent several of his hand-made hollow tubes to the Royal Society for them to see with their own eyes. The drawings and explanations thus gave the information needed for the Fellows to use the tubes they were sent (AdB,1:100– 103). In his next letter, dated 6 July 1674, Leeuwenhoek drew another glass tube in the margin, but also added the results of his observations. He had identified globules in the fat from a cow and a sheep by looking at it in the glass tube with a microscope (fig. 7) (AdB, 1:116–31).17 This letter should be seen as a turning point, in which Leeuwenhoek not only gave information about his methods of seeing and observation by drawing the apparatus he was using, but also started to report visually on his observations with his own drawings. It was a half year later, in December 1674, that Leeuwenhoek sent another image, this time made for him by a draughtsman. Leeuwenhoek commented in his letter that he had mounted his specimen—the optical nerve of a cow—on a microscope and that he “had it drawn up” (AdB, 1:200–201).18 In contrast to Leeuwenhoek’s own drawings, which were all produced in writing ink, this drawing was made with graphite instead. It was drawn on a separate piece of paper, which was sent and kept with the letter (fig. 8).19 The next letter that came with drawings included a new apology: I have drawn the figures made by the salts of herbs as well as I could (but I have not been able to delineate all the particles to perfection) and send you these enclosed (see fig. 9). (AdB, 1:232–33)20

16. AdB, Letter 8 (1 June 1674). 17. AdB, Letter 9 (6 July 1674). 18. AdB, Letter 13 (4 December 1674): “het selve laten uijt teijckenen.” 19. There is a copy of this image in the British Library, Add MS 22953, f. 125. That drawing is made in red chalk, is in reverse, and contains more small details than the drawing at the Royal Society. It makes me wonder whether the British Library manuscript is the original from which the Royal Society’s copy was made (by an unknown person) by copying the image with a chalk method. In a following letter (AdB, Letter 14), Leeuwenhoek wrote to Constantijn Huygens with extracts of two of his letters to the Royal Society, one being the letter from 4 December 1674. He wrote that he sent a copy of the drawing he had made of the optical nerve. If this letter and drawing to Huygens are the ones in the British Library, then it could indeed be the copy Leeuwenhoek mentioned, or even a third copy. For a contemporary manual with information about copying images, see Thomas Jenner’s ABookofDrawing(1647, pp. 9–10). Many thanks to Kim Sloan and Richard Stephens for their advice on early modern methods of copying drawings. 20. AdB, Letter 16 (11 February 1675): “Ick heb de ﬁgueren die de souten vande planten hebben gemaect, na mijn vermogen nageteickent, (maer de volmaecktheden die in veel deeltgens wel vereijschte sij mij niet doenlijck geweest te volgen) die ick UEdt hier ben sendende.”

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Figure 7. Antoni van Leeuwenhoek, Fat globules, 6 July 1674. Ink on paper. 22 × 30 mm. London, Royal Society archives, EL/L1/5 (detail). (Photo © The Royal Society).

These drawings of salts are indeed of quite a different quality than that of the optical nerve. What is more, all are in ink instead of graphite or red chalk. In contrast to Leeuwenhoek’s previous drawings, for which he could at least partly rely on his ruler and compasses, the salts in herbs were not as geometrically regular and thus needed a free hand to draw. Seeing his “unschooled” hand drawing of those salt crystals, it is all the more interesting to look at his next drawings, from 31 May 1678, three years after these salt drawings. Here we ﬁnd three drawings made in ink, but with a subtlety in cross-hatching, some perception of depth, and a generally detailed depiction of the strands and vessels in the sperm of a dog (ﬁg. 10). Once again, Leeuwenhoek apologized: Moreover, there are also vessels within the above-mentioned circumference that nearly elude observation, cannot be followed by me with the eye and have not been drawn by me. As I am not an expert at drawing [teeckenkonst], I hope you will be able to see how these vessels cross each other (AdB, 2:364–65).21

21. AdB, Letter 39 (31 May 1678): “Bovendien leit inde verhaelde spatie, noch vaaten, die om haer kleijnheijt bij na het gesicht ontwijcken, en die ick hier niet en heb geteijckent, noch voor mij niet en sijn te volgen, en nademael ick de teeckenkonst niet en versta, soo wil ick echter hoopen, dat UEdele sal connen sien, hoe de vaaten, over en door malcanderen loopen.”

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Downloaded from http://www.mitpressjournals.org/doi/pdf/10.1162/posc_a_00314 by guest on 26 September 2021 Figure 9. Antoni van Leeuwenhoek, Crystalisations of several liquids, 11 February 1675. Ink on paper. 302 × 202 mm. London, Royal Society archives, EL/L1/11, p. 21. (Photo © The Royal Society).

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Figure 10. Antoni van Leeuwenhoek, Vessels in dog’s sperm, 31 May 1678. Ink on paper. 152 × 193 mm. London, Royal Society archives, EL/L1/36. (Photo © The Royal Society).

In Dutch Leeuwenhoek used the word “teeckenkonst,” or art of drawing, to determine the skill he lacked. However, these drawings show that he had certainly improved. While it is indeed unlikely that he received any formal training in drawing, something that would not necessarily have been uncommon for a person of a noble or gentry background, it is becom- ing clear that the medium of drawing might impact his notion of expertise in this context (Sloan 2000, p. 11). The drawings that Leeuwenhoek had made by artists (see the next section) were all done in red chalk, graphite, and even paint, while his own drawings, at least up to this point, were made with his writing quill, with ink. That changed with his letter from 12 January 1680, in which Leeuwenhoek investigated vessels in all types of wood. With this letter Leeuwenhoek sent nineteen figures drawn by himself, of which eighteen were done in red chalk. Regarding his first figure (see fig. 11) he explained how it was a piece of oak wood, seen through a microscope, which in real size was as small as the figure

Downloaded from http://www.mitpressjournals.org/doi/pdf/10.1162/posc_a_00314 by guest on 26 September 2021 Figure 11. Antoni van Leeuwenhoek, Oak wood, 12 January 1680. Red chalk on paper. 308 × 122 mm. London, Royal Society archives, EL/L1/49, p. 15 (detail). (Photo © The Royal Society).

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designated with H.22 “Fig. 1 ABCD shows a piece of oak, drawn by me as well as possible through one of my microscopes” (AdB, 3:150–51).23 To eliminate any doubt about whether or not Leeuwenhoek drew these images himself, he discussed in the letter the process of image making and the transferring of these images for his correspondence.24 Though I cannot draw at all [hoe wel ick gansch niet teickenen kan], I have put the aspect of the wood to paper in red chalk to the best of my ability. I had a copy made in black chalk by someone else, but when I tried to print it, I made the paper a little too wet and thus mostly spoiled it. Though the copy was very accurate, I yet send you enclosed my red-chalk drawing, because the little vessels ﬁgured in it are smaller and agree better with the nature of the wood. (AdB, 3:164–167)25 This quotation gives us a wealth of information about Leeuwenhoek’s drawing practices in his comptoir in Delft. It is clear that he himself made the drawings in red chalk. He had copies made of his originals by “een ander,” or another person (not identifying the gender), with a different type of chalk (ﬁg. 12). Was this done so that the different drawings could be easily distinguished? Or was there another reason for the change of drawing materials? Clearly the aim of making the copy was to be able to print (“afdrucken”) even more copies. This “printing” process was a manual copying process in which the reverse side of a drawing was rubbed with red or black chalk and put on a wet piece of paper. By tracing the original drawing with a piece of chalk or slightly pointed object, the outlines of the drawing would be transferred onto the wet paper (AdB,3:164–65, fn 81/32). In the case of this drawing by Leeuwenhoek, he also sent a copy in black chalk to the Royal Society and we can see water damage in the image. However, from

22. Robert Hooke did exactly the same in his Micrographia (1665) to show the original size and the magniﬁed size, for example in Plate II and Plate XXI. 23. AdB, Letter 54 (12 January 1680): “Fig. 1 ABCD. vertoont een stuckie eijckenhout, dat ick door een van mijn microscopen, soo veel als het mij mogelijck was heb afgeteickent.” 24. Many of his images will have existed in copies, so that he could have sent them to other correspondents interested in his observations: he was for example in correspondence with Constantijn Huygens, to whom he regularly sent copies of his letters to the Royal Society. Leeuwenhoek also sent to the Royal Society copies of his letters to Huygens. 25. AdB, Letter 54 (12 January 1680): “Jck heb de gedaente van het hout, hoe wel ick gansch niet teickenen kan, na mijn vermogen met root krijt op het papier gebracht, en het selvige door een ander met swart krijt laten na teijckenen, maer alsoo ick het selvige wilde afdrucken, en het papier daer toe wat te nat nemende is het te merendeel bedorven, en al hoe wel het na geteickende seer net was, soo sende ick echter het gene dat ick met root krijt selfs hebbe geteickent hier mede uijt in sichte om dat de kleijne afgebeelde vaaten, aldaer kleijnder staen, ende met de natuer van het hout beter over een komen.”

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this drawing now at the Royal Society it is not clear whether it would have been the copy made “by someone else” or Leeuwenhoek’s own failed attempt at a copy. Interestingly, Leeuwenhoek also commented on the quality of the copy made by the other person as “very accurate,” but he was also critical about the size of “thelittlevessels” as portrayed by the copyist, and he pre- ferred his own drawing. This was similar to a comment Leeuwenhoek made about the very ﬁrst drawings he had made and sent to the Royal Society (of his observations on the sting of a bee), where he said that “the proportions have not been observed as accurately as I could have wished” (AdB,1:42–43).26 Leeuwenhoek’s caution towards the skill of his draughtsmen and copyists shows a very important awareness of the function and role his images played in his communication with the Royal Society and others. He put himself in the role of an authority. Even though his drawing skills might not have been excellent, at least the drawing showed exactly the right proportions of the object observed. This means that the accuracy of the thing depicted was more important to him than the skill with which it was put on paper. In this way he made sure that the Fellows of the Royal Society could be certain that all the images he sent were the “precise” depictions of what he had seen through his microscope. Leeuwenhoek continued to send drawings by his own hand to the Royal Society in the following two years, with the last one on 3 March 1682, when he once more mentioned that he did what he could in terms of drawing, since he could not draw (“alsoo ik niet teikenen kan”)(AdB, 3:394–95).27 However, after this date, and for the next forty-one years of his correspondence with the Royal Society, he did not send any more drawings made by himself. That might have to do with his self-awareness as an untrained draughtsman. What seems more likely, however, is that he started collab- orating more intensely with draughtsmen during the preparation of published versions of some of his letters that appeared with engraved illus- trations from 1684 onwards. His letters were ﬁrst published by Daniel van Gaesbeeck in Leiden, and according to the Opdragt, or preface, it was not Leeuwenhoek himself who approached him, but a physician from Delft, named Cornelius van ’s Gravesande (Leeuwenhoek 1684, Opdragt).28 Van Gaesbeeck also mentioned that the plate-cutter, or engraver, Abraham de

26. AdB, Letter 2 (15 August 1673): “doch de proportie en is niet wel gevolght, dat ick wel gaerne anders had gesien.” 27. AdB, Letter 67 (3 March 1682). 28. This publication contains two letters (AdB, Letters 62 and 65), which were originally sent to Thomas Gale FRS and Robert Hooke FRS in June and November of 1680 respectively.

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Blois made the engravings for this publication. It is with the subsequent publications of more letters, by the publisher Cornelis Boutesteyn, that Leeuwenhoek started his own collaboration with printers, publishers, and plate-cutters.

4. Drawings by Draughtsmen Just before Leeuwenhoek started publishing his own letters, he was elected a Fellow of the Royal Society in the spring of 1680. This might have been another reason to “professionalize” the making of images for his correspondence as well as his publications. The drawings made by those other than Leeuwenhoek can be grouped chronologically into three periods: from the beginning of his correspondence until 1689 (see Table 1B); from 1692 until 1712 (see Table 2); and from 1713 until his death in 1723 (see Table 3). For the gaps between these periods there are no drawings available in the Leeuwenhoek letters at the Royal Society archives, and therefore we cannot determine any hands for those years. The first period is characterized by many different hands including Leeuwenhoek’s own. The second and the third periods both have much greater continuity in the style of images. Purely on the basis of the drawings we might be able to conclude that Leeuwenhoek worked closely with two draughtsmen consecutively from 1692 onwards. The drawings prepared by draughtsmen in the first period that are still kept in at the Royal Society today, fifty-eight in total, were done on paper and vellum using a variety of techniques: graphite, red chalk, colored chalk, grey wash, and ink and body color. Due to the use of these different techniques, and the small sample size of the drawings, it is very hard to compare the drawings for style. A draughtsman might well have been able to draw images with different materials and techniques, which might have led to stylistically rather different images by the same artist. Let us look at a few examples. The drawings made with grey wash, such as the drawing of a skinned rat’s testicle in a jar of water, show how this particular draughtsman was able to draw and fill up the background of the things depicted (fig. 13).29 In this case the vessels in the testicle were left blank and it is the surround- ing that was drawn with grey wash. The same is the case for the surface change from the water to air in the glass jar. Because the draughtsman left a subtle circle blank, we automatically perceive the surface of the water against the jar. A similar technique was used six years later in the drawings of a kapok seed (fig. 14).30 However, these drawings of seeds in grey wash

29. Royal Society archives, EL/L1/52. 30. See the drawings in Royal Society archives, EL/L2/4.

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Drawings and Hands in Period 2 (1692–1712) Letter no. Dates of Archive No. of Drawing Number in AdB letter to RS reference ﬁgures Technique Draughtsman Comments

1 120 22 April 1692 EL/L2/35 4 Red chalk Period 2 draughtsman 2 193 9 May 1698 EL/L3/3 5 Red chalk Period 2 draughtsman 3 204 25 September 1699 EL/L3/12 5 Red chalk Period 2 draughtsman 4 218 7 September 1700 EL/L3/21 4 Graphite Henry Hunt These drawings were made at the RS after specimens Leeuwenhoek sent to London. 5 219 26 October 1700 EL/L3/23 5 Red chalk Period 2 draughtsman 6 220 25 December 1700 EL/3/25 7 Red chalk Period 2 draughtsman 7 221 28 January 1701 EL/L3/26 8 Red chalk Period 2 draughtsman 8 226 21 June 1701 EL/L3/29 8 Red chalk Period 2 draughtsman 9 225 21 June 1701 EL/L3/31 3 Red chalk Period 2 draughtsman 10 234 14 February 1702 EL/L3/42 3 Red chalk Period 2 draughtsman 11 239 28 December 1702 EL/L3/47 7 Red chalk Period 2 draughtsman 12 240 5 February 1703 EL/L3/49 11 Red chalk Period 2 draughtsman 13 241 26 February 1703 EL/L3/51 22 Red chalk Period 2 draughtsman 14 244 4 December 1703 EL/L3/56 13 Red chalk Visiting painter? These drawings are in a different hand, maybe one of the visiting painters (see pp. 41–43 in this article)

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Drawings and Hands in Period 3 (1714–1722) Letter no. Dates of Archive Archive reference No. of Drawing Number in AdB letter to RS reference image original letter ﬁgures Technique Draughtsman Comments

1 311 20 November LBO/15/170 EL/L4/56 4 Ink and Willem 1714 grey wash vander Wilt 2 347 9 January 1720 LBO/15/298 EL/L4/60 2 Ink and Willem grey wash vander Wilt 3 348 20 November LBO/15/231 EL/L4/58 7 Ink and Willem Letter is wrongly 1720 grey wash vander Wilt dated in LBO as 15 January 1723 4 349 15 January 1721 LBO/15/302-303 EL/L4/62 2 Ink and Willem grey wash vander Wilt 5 351 11 April 1721 LBO/16/203 EL/L4/65 7 Ink and Willem grey wash vander Wilt 6 357 13 June 1722 LBO/15/269 EL/L4/79 5 Ink and Willem grey wash vander Wilt 7 359 7 July 1722 LBO/15/284 EL/L4/81 3 Ink and Willem grey wash vander Wilt 8 360 20 November LBO/15/284 EL/L4/83 9 Ink and Willem 1722 grey wash vander Wilt TOTAL DRAWINGS PERIOD 3 39

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Figure 13. Unknown draughtsman for Antoni van Leeuwenhoek, Skinned rat’s testicle in glass jar, 5 April 1680. Grey wash and ink on paper. 99 × 104 mm. London, Royal Society archives, EL/L1/52. (Photo © The Royal Society).

are part of a larger series of drawings, the others all made with red chalk. In these red chalk drawings there are no shadows added to the figures, in contrast to both the drawings in grey wash, even though there is no tech- nical reason not to add shadows in red chalk. Consequently, I suspect that the two drawings in grey wash were done by the same person, the drawings in red chalk by someone else. Three that differed spectacularly from all the other images in the Leeuwenhoek correspondence are drawings of insects (see fig. 15 for one example).31 They were done in a combination of ink, body color, and grey wash on vellum, and it is the detail, the fine lines of the hairs on the legs of the fly and the beetle, as well as the veins in the wings of the dragon flies, that stand out in their subtlety. These images are unique in their penman- ship of subtle, thinly applied lines, combined with the use of color in part of the image. This draughtsman’s style is so uniquely different from the other drawings that it seems that this person worked for Leeuwenhoek only once.

31. Royal Society archives, EL/L1/62, p. 21.

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Figure 14. Unknown draughtsman for Antoni van Leeuwenhoek, Cotton seeds, 10 June 1686. Grey wash on paper. 133 × 83 mm. London, Royal Society archives, EL/L2/4 (detail). (Photo © The Royal Society).

In most of the drawings a figure number has been added. Comparing Leeuwenhoek’s handwriting, such as on the copy of his original drawings in red chalk of the structures of oak wood (fig. 11), it seems that he often put the figure numbers in himself. Throughout this period he used both ink and red chalk to add these marks. This makes sense given that he must have ordered the drawings before he finished writing his letters, as he referred to them in the text. Altogether it looks like there have been four different draughtsmen working for Leeuwenhoek in this period, but there might also have been fewer if indeed they each used multiple techniques and drew in multiple styles. All drawings in the second period, 209 in total, were made in red chalk (see Table 2).32 They were sent with letters between 1 April 1692 and 12 April 1712, exactly 20 years worth of correspondence. The drawings show a striking similarity throughout the entire period. The red chalk was applied to the paper with seemingly similar pressure and all drawings

32. There is one exception in the drawings kept with Leeuwenhoek’s letter from 7 September 1700 (EL/L3/21; AdB, letter 218). The four ﬁgures made with graphite were drawn by Henry Hunt at the Royal Society. On his work as draughtsman for the Royal Society, see Sachiko Kusukawa (2011, 2019).

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Figure 15. Unknown draughtsman for Antoni van Leeuwenhoek, Two cockchafers, 12 November 1680. Body color and ink on vellum. 76 × 85 mm. London, Royal Society archives, EL/L1/62. (Photo © The Royal Society).

contain shading and a similar level of detail. Most of the drawings in this period had the figures’ names written in one particular hand. This draughtsman always added a small circular flourish (not unlike a little dot) to the bottom of his “f”s and sometimes “g”sin“fig,” when using ink and red chalk (figs. 16 and 17). It is identifiably different from the hand of Leeuwenhoek, who occasionally added the figure numbers himself in this period (fig. 18). Based on the similarity in style of the drawings, as well as the handwriting of the figure numbers, I would suggest that we are dealing with one draughtsman who worked for Leeuwenhoek during this entire period.33 The final and third period also only has drawings by one person, thirty- nine in total. In contrast to the much-used red chalk in the previous two periods, all these drawings were made in ink with grey wash. The figure numbers were consistent throughout this period, and clearly differed from

33. One sheet with drawings seems to have a different style (EL/L3/56/009), and I wonder whether these were made by one of the three painters (discussed below) who came to Leeuwenhoek’s comptoir, or by Leeuwenhoek himself. The handwriting is certainly Leeuwenhoek’s, but he did not say in the letter that he drew the images himself, which he usually did mention.

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Figure 16. Unknown draughtsman of period 2, untitled, 22 April 1692. Ink on paper. 10 × 17 mm. London, Royal Society archives, EL/L2/35 (detail). (Photo © The Royal Society).

Figure 17. Unknown draughtsman of period 2, untitled, 3 October 1704. Red chalk on paper. 12 × 20 mm. London, Royal Society archives, EL/L3/68 (detail). (Photo © The Royal Society).

Figure 18. Antoni van Leeuwenhoek, untitled, 25 December 1702. Ink on paper. 12 × 20 mm. London, Royal Society archives, EL/L3/47 (detail). (Photo © The Royal Society).

Figure 19. Willem vander Wilt, untitled, 20 November 1714. Ink on paper. 7 × 20 mm. London, Royal Society archives, LBO/15/170 (detail). (Photo © The Royal Society).

Leeuwenhoek’s hand, or that of any other draughtsman from earlier periods (ﬁg. 19). All these drawings can now be found in the Letter Book series in the Royal Society archive, and not, as with all the other drawings, in the Early Letters together with the original letters in Leeuwenhoek’s hand.34 In Letter Book 15, which covers the period from 1713 to 1723, there is a section of about 270 pages containing consecutive letters that were originally written by and to Leeuwenhoek. They must have been copied into this Letter Book all at once, after the ﬁnal letter of this series had arrived.

34. For a short explanation of the various archival and administrative series at the Royal Society, see Fransen, Reinhart, and Kusukawa, forthcoming (2019).

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Some of the letters contain images, and some of these drawings were printed in the Philosophical Transactions. This raises the question of whether the drawings could have been made at the Royal Society, copied from the printed versions, and thus whether or not they are the drawings originally sent to London by Leeuwenhoek. However, there is one letter that proves that all of these drawings, which are similar in style and hand, indeed came with the letters sent by Leeuwenhoek. His original letter from 15 January 1723 contains the remains of images that were stuck to its pages but have been removed (fig. 20). The glue used left a very particular stain on the page, which is the same as the stains found on the two drawings on pages 302 and 303 in Letter Book 15 (fig. 21). And although it is hard to distinguish due to the glue, both of these images are indeed drawings, as can been seen from the small detail of the image on page 302 (fig. 22). Both images also have the original image numbers as referred to by Leeuwenhoek in his letter, corrected to the numbers that were used when of the letter was printed in the Philosophical Transactions (fig. 23). From this example and the fact that both the handwriting on the images and the style of all images from 1714 onwards are the same as these two images from 1723, we can conclude that Leeuwenhoek worked once more with one draughtsman from 1714 at the latest until his death in 1723. There was a great absence of images sent between 1714 and 1720—no original images are left from those six years, the longest period without images. This can be explained by the editorship of the Philosophical Transactions of Edmond Halley FRS. Since he had not shown any interest in publishing letters by Leeuwenhoek during his first term as editor (1685–1693), Leeuwenhoek knew what to expect from Halley’s second period as editor.35 And indeed there was only one article from a Leeuwenhoek letter published during Halley’s second term from 1715 until 1719.36 Leeuwenhoek ceased his entire correspondence with the Royal Society in November 1717, picking up writing again only in November 1720 when Halley left his position and a new Secretary and editor, James Jurin FRS, took over.

35. In the ﬁrst issue of the Philosophical Transactions published under the editorship of Edmond Halley (1686), he advertised that he was going to publish about experiments and “other useful discourses or relations concerning Physical, Mathematical, and Mechanical Theories or Observations,” and thus excluding experiments and observations of what we would now call the biological sciences (Halley 1686, p. 2). On Halley as editor, see also Feingold (2001). 36. Edmond Halley did not publish Leeuwenhoek’s letters nor any other letters that dealt with the biological sciences during his ﬁrst term as editor. This might have led to Leeuwenhoek starting to publish his letters himself. For more information on the impact of editors and what they published in the Philosophical Transactions, see Moxham (2015).

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Figure 20. Glue stains, 15 January 1621. Ink and glue stains on paper. 230 × 182 mm. London, Royal Society archives, EL/L4/62. (Photo Author).

5. Identity of the Draughtsmen Whether Leeuwenhoek mentioned the presence of draughtsmen in his comptoir or only referred to them in the passive voice (e.g., “Ihadthe images made”), he never mentioned any of them by name. Although the draughtsmen were not entirely absent from his correspondence, Leeuwenhoek made them into his unacknowledged assistants of his

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Figure 21. Willem vander Wilt, Cut-out drawings of microscopic observations of the skin of a peach and a quince with glue stains, 15 January 1621. Grey wash and ink on paper. 317 × 190 + 190 mm. London, Royal Society archives, LBO/15, pp. 302–303. (Photo © The Royal Society).

scientiﬁc practice.37 He did refer to other people by such designations as: Fellows of the Royal Society; visitors to his comptoir at home; people who brought him specimens for further research; or messengers, merchants and ship captains who could be trusted with mail to London. Those visitors were not, however, credited with having helped in Leeuwenhoek’sownwork. Quite the contrary, they would give a certain status to Leeuwenhoek’s household by their curiosity in his investigations into nature. By not giving the names of his draughtsmen, Leeuwenhoek kept the honour of the work to himself, which stands in contrast to the way he also relied on them as witnesses, as will be discussed in the next section. In 1729, Reinier Boitet (1691–1758), a publisher, author, and poet in Delft, published an updated version of Dirk van Bleiswijk’s Beschrijvinge der stadt Delft [Description of the city of Delft] (1667). Bleiswijk’s book contained descriptions

37. See for a wider discussion of “invisible technicians,” Shapin (1989) and Morus (2016).

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Figure 22. Willem vander Wilt, Microscopic observations of the skin of a peach, 15 January 1621. Grey wash and ink on paper. 71 × 82 mm. London, Royal Society archives, LBO/15, p. 302 (detail). (Photo © The Royal Society).

of illustrious and famous inhabitants of Delft, including artists and painters.38 In the updated version, also entitled Beschryving der Stadt Delft, Boitet included the descriptions of several more artists’ lives, combining Bleiswijk’s biographies with descriptions that had previously been published by Karel van Mander and Arnold Houbraken (Boitet 1729).39 On top of using and combining earlier lives, Boitet wrote new biographies of artists who had lived and worked in Delft since the publication of the aforementioned biographies. This included an interesting entry on Thomas vander Wilt (1659–1733). Thomas vander Wilt was still alive when Boitet published his book and was praised for his craftsmanship and his skill in portraiture. He was trained by Johannes Verkolje (1650–1693), the Delft-based painter who had drawn

38. This book contains a large chapter on illustrious inhabitants of Delft, including learned men, princes, and artists. 39. As previously mentioned by Dobell (1932), Boitet’s book contains a chapter dedicated to painters (Boitet, Ch. 15 “Lofrede der Schilderkunst,” pp. 771–93), which is pre- ceded by an entire chapter on learned men, including Leeuwenhoek (Boitet, Ch. 14 “Lof der wysheit en geleertheit,” pp. 661–770). For his chapter on painters, Boitet relied on Karel van Mander (1604) and Arnold Houbraken (1718–21).

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Figure 23. Unknown engraver, Microscopic observations of the skin of a peach and a quince, in Philosophical Transactions 31, issue 369, 1721. Engraving. 82 × 178 mm. London, Royal Society archives, EL/L4/62. (Photo © The Royal Society).

up Leeuwenhoek’s portraits in both oil and mezzotint (see ﬁg. 1). Vander Wilt painted portraits of close acquaintances of Leeuwenhoek, such as the latter’s minister Pieter Gribius, and his friend Hubert Korneliszoon Poot. Vander Wilt also wrote a laudatory poem on Leeuwenhoek, published in Leeuwenhoek’s last publication in Dutch, Send-brieven (1718).40 Most interestingly though, in the entry in the Beschryving, Boitet also mentioned Thomas’s son Willem (1691–1727), who had died at the age of 35, just two years before Boitet published his book. Boitet wrote that: Willem […] who was in drawing, by education of his father, so advanced, that not many could equal him. From him are also most of the plates in the famous work by Mr Leeuwenhoek, through magnifying glasses wonderfully drawn after life. (Boitet 1729, p. 791)41 There is no reason to doubt this statement, as Clifford Dobell already mentioned in his 1932 biography of Leeuwenhoek (Dobell 1932, p. 344). The problem is to identify what it was exactly that Willem vander Wilt did for Leeuwenhoek. He cannot have produced most of the plates for

40. Two more ﬁrst editions of Latin translations of Leeuwenhoek were published in 1619, and several second, third, and fourth editions of earlier publications were published up to 1730. See Anderson (last accessed on 23 February 2019), https://lensonleeuwenhoek. net/timeline/tax/publications. 41. “Hy hadde by zyn huisvrouw Johanna Biddaff, een zoon, Willem genaamt, die in teikenen, door onderwys van zyn vader, zoo verre gevordert was, dat ‘er weinig zyn weerga waren. Van hem zyn ook meest alle de platen in het vermaarde werk van den heer Leeuwenhoek, door vergrootglazen wonderlyk na het leven geteikent.”

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Leeuwenhoek since he was only born eighteen years after Leeuwenhoek’s ﬁrst correspondence with the Royal Society. But Boitet seems to refer to printed works with the word “platen” in Dutch, which would be short for “copper plates.” He also speaks of the “work,” something that is unlikely to refer to letters. It might therefore be the case that Vander Wilt was the copperplate engraver and etcher for the latest printed collection of Leeuwenhoek’s letters, which he published in 1718 under the name Send-brieven. This collection of forty-six letters contains his letters to the Royal Society and other correspondents between 8 November 1712 and 20 November 1717. From the analysis of the original drawings in the previous section, there is a clear-cut difference in style between the drawings that Leeuwenhoek sent to the Royal Society until April 1712, and the drawings that were sent from 20 November 1714 onwards. The style of drawings from 1714 until Leeuwenhoek’s death in 1723 stays the same. In addition to the stylistic elements, Leeuwenhoek wrote in a letter from 1721 about the painter who had been painting his discoveries for several years, which seems to conﬁrm the employment of one draughtsman during this last period of his life.42 Based on these analyses, we can conclude that Leeuwenhoek’s draughtsman from 1714 until 1723 was Willem vander Wilt, which gives us the name of at least one of his collaborators.43 Additionally, a letter from March 1713 from Leeuwenhoek to the Delft burgomaster Jan Meerman also contains a drawing from the hand of Willem vander Wilt. This letter, now kept at the Royal Library in The Hague, shows that Vander Wilt was already working for Leeuwenhoek as early as March 1713.44 Dobell speculated that Willem’s father, Thomas, might have done some of the drawings and cuttings for Leeuwenhoek in earlier years. However there is no evidence for that. Nor is there any document that allows us to pin down the mysterious “draughtsman, who had also been a silversmith in his young years,” whom Leeuwenhoek summoned in 1705 to come and observe silver (AdB, 15:140–41).45 In short, we know there was one draughtsman working for Leeuwenhoek between 1692 and 1712, but we still do not know his identity.

42. Unpublished letter, Royal Society archives, EL/L4/63/004 (24 January 1721, to the Royal Society). 43. Many thanks go to the current editors of the Leeuwenhoek correspondence, Douglas Anderson and Huib Zuidervaart, who have done extensive archival research in Delft to ﬁnd more names of potential Leeuwenhoek draughtsmen. Despite the fact that there were many draughtsmen in Delft at the time, there is no evidence for any of them working for Leeuwenhoek. 44. The Hague, Royal Library, KW 130 C1, fol. 451. The image is reproduced as Plate VII, in AdB 17. 45. AdB, Letter 256 (12 March 1705, to Antonio Magliabechi): “Hier op ontboode ik den Teijkenaar, die in sijn jonge jaren ook een silver smit hadde geweest.”

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6. Draughtsmen as Collaborators Despite the fact that Leeuwenhoek said repeatedly that he could not draw himself, he designed many images that he sent to the Royal Society. How- ever, even more of the drawings he mailed to London were made by draughtsmen. In various ways, these men are present in Leeuwenhoek’sletters. Sometimes they were present passively, for example when Leeuwenhoek wrote about the image of the bee sting that he had made in response to Oldenburg’s request for images, Leeuwenhoek commented that “Ihave had them drawn for me, but the proportions have not been observed as accurately as I could have wished” (AdB, 1:42–43).46 This short comment shows that Leeuwenhoek was dependent on the skills of his draughtsmen, skills that can be divided into seeing and drawing. While in the English translation, the term “observed” seemingly comments on the lack of skill of seeing in the draughtsman, the Dutch original text is actually more precise, stating that the proportions have not been followed as accurately (“de proportie en is niet wel gevolght”). With this explanation the emphasis of the draughtsman’s skill lay not just in observing, but in following by hand what he saw through the microscope. It is clear that Leeuwenhoek had seen different proportions when he had looked at the same specimen. However, apart from the short phrase “laten uitteijcken” (had [them] drawn), which implies the presence of a second person involved in the process, Leeuwenhoek avoided naming an actual draughtsman by using the passive voice.47 On other occasions, artists were much more present in Leeuwenhoek’s descriptions. Thirty years after the first exchanges of letters and drawings, Leeuwenhoek drew his readers with him into his working space when de- scribing his observations of grains of sand. One of the grains was slightly larger and flatter than the others, and Leeuwenhoek exclaimed: This grain of sand was wonderful, and the first to see it were three artists, all of whom looked at it with amazement; one of them, who was not the least among them, offered his services to draw such a wonderful grain of sand, and a second asked whether he might copy the drawing, so that he could show some curious persons what was to be perceived in a grain of sand. (AdB, 14:274–75)48

46. AdB, Letter 2 (15 August 1673): “ick heb deselve […] laten uijtteijcken, doch de proportie en is niet wel gevolght, dat ick wel gaerne anders had gesien.” 47. Leeuwenhoek did not only use the passive voice to talk about drawings, there are also places where he speaks about the draughtsman doing something, but he never adds a name. 48. AdB, Letter 244 (4 December 1703): “Dit zand was verwonderenswaardig, ende de eerste die het sagen dat waren drie konst schilders, die het alle met verbaastheijt aan sagen, en een vande selve die niet de minste was, presenteerde sijn dienst, om soo een verwonde- rens waardig zand te mogen afteijkenen, en een tweede, dat hij de af teijkening mogte na teijkenen, om eenige lief hebbers te laten sien, wat in een zand te bekennen was.”

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Figure 24. Unknown artist for Antoni van Leeuwenhoek, Grain of sand with ruined temple, altar, pillars, and people with hands in the air, 4 December 1703. Red chalk and ink on paper. 50 × 46 mm. London, Royal Society archives, EL/L3/56 (detail). (Photo © The Royal Society).

Leeuwenhoek often received visitors in his house and comptoir, and in this case the konstschilders (artists) were likely to be his guests and not his usual workmen. This is conﬁrmed by his terminology, as he commonly used the words teykenaar (draughtsman) or plaat-snyder (engraver) for the people who worked for him. Nevertheless, one of the artists drew his observations, and it is either these drawings, or a copy of these drawings, that were sent to the Royal Society (ﬁg. 24).49 In this grain of sand, which is designated by GHIKL in Fig. 2, one might see not only, as it were, a ruined temple with some pillars, but in a corner, designated by GHI, there seemed to be two kneeling

49. See fn. 34.

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figures extending their arms towards something resembling an altar at some distance therefrom. (AdB, 14:274–75)50 It is here that the reader(s) of the letter became part of the conversation that had occurred in Leeuwenhoek’s comptoir. The microscope must have been mounted on a certain stand to make sure that the specimen was kept in place, so that the four men could have taken turns to look through the minutely small lens to observe this wonderful landscape in a grain of sand. Followed by and parallel to the observations, one of the artists took some paper and red chalk to sketch out the ruins and kneeling figures, to preserve this wondrous grain of sand for potentially disbelieving, yet curious friends. It is either that first drawing or a copy of grain-with-ruin that made it to the Royal Society with Leeuwenhoek’s letter of 4 December 1703. In the records of the meetings of the Royal Society in the Journal Book, we find on 26 January 1704 that “a Letter was read from Mr Leeuwenhoeck concerning the Figures of Sand; he was Thanked, and the Transactions he wants, order’d to be sent him.”51 Leeuwenhoek and his guests saw something in this grain of sand that they could not have seen. However, the fact that all four of them “saw” it and subsequently drew what they saw, validated the observation. In this way Leeuwenhoek was using the presence of other people and their observations as a confir- mation of his own, thereby copying the practices of the Fellows of the Royal Society of collaborative experimenting and observing. As we have seen in the section on the draughtmen’s identities, Leeuwenhoek once summoned a silversmith to his comptoir (see fn. 45). However, this silversmith was not necessarily invited for his drawing skills (if so, he might have been the draughtsman of the second period). It is more likely that he was asked to act as a witness to confirm that the silver Leeuwenhoek had managed to create out of a solution in aqua fortis through crystallization was actually silver. And it was thus the expertise of the draughtsman’s silversmithing background that was of use here, not his drawing skills. Similarly Leeuwenhoek used his draughtsmen to act as his witnesses, even if they were not necessarily experts on the objects observed. For

50. AdB, Letter 244 (4 December 1703): “In dit zand dat met ﬁg: 2 GHIKL. werd aan gewesen, vertoonden niet alleen, of men in een vervallen Tempel quam in te sien, met eenige Pilaren, maar in een hoek als met GHI: aan gewesen verbeelde te leggen, twee geknielde Beeldekens, die haar narmen uijt staaken na een verbeeld altaar, dat een weijnig daar vandaan was.” 51. Royal Society archives, London, JBO/11/40. The letter and images were also printed in Leeuwenhoek (1704).

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Figure 25. Unknown draughtsman for Antoni van Leeuwenhoek, two unborn shrimps, 10 June 1686. Red chalk on paper. 120 × 88 mm. London, Royal Society archives, EL/L2/4 (detail). (Photo © The Royal Society). example in 1686, when Leeuwenhoek was investigating the reproduction of shrimp and how their eggs already had a little shrimp inside them once they were fertilized (ﬁg. 25). To give his observations the necessary value and authority, Leeuwenhoek not only relied on drawings to support his observations, but he also invited his draughtsman to be his witness. In his letter of 10 June 1686 to the Royal Society, he wrote: In order to place before Your Honours’ Eyes the makings of an unborn shrimp, I have taken several of the same from the eggs, and placed four of these before my microscope, and had a draughtsman come to my house, and instructed the same to follow the ﬁgure, as it

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appeared to him, as closely as possible, without my wanting to tell him what that he was drawing; the same said many a time, while he was drawing: I don’t know what I am drawing, but it seems to me that it is a shrimp. (AdB, 6:110–11)52 The draughtsman was thus brought to the house not only for his drawing skills, but also for his skills in seeing. He was asked to make a judgment about his observations, not as an expert draughtsman but as an unbiased lay observer.53 The draughtsman was the person who needed to observe carefully and subsequently draw the object. Even without knowing what he saw, he should have been able to draw it and could si- multaneously have been used as an additional witness in Leeuwenhoek’s practice of observing new phenomena. From a letter to the Royal Society from 1693, it becomes clear that the draughtsman could also have a restricting effect on the communication of observations. In this letter, Leeuwenhoek relates experimenting with fleas. He carried a little flask with him in which he put flea worms, to let them become pupae and subsequently fleas. Leeuwenhoek observed minute details such as the blood vessels in the fleas’ bodies, which he described in his letter. But it was the draughtsman who provided the limits of what could be communicated. Leeuwenhoek commented in his letter that, “Fig. 6 ASTV shows the Pupa in so far as the Draughtsman was able to depict it” (AdB,9:230–31) (fig. 26).54 He continued, “And although very many blood vessels were seen, especially in the abdomen, he [the draughtsman] was able to represent only a few of them, saying that it was impossible to follow the others.”55 In the original Dutch text the words used for drawing are “aanhalen,” to represent or cite, and “volgen,” to follow, which connects the processes of seeing with those of drawing. Leeuwenhoek continued his letter by mentioning his maid who came into his comptoir to bring him a little glass tube in which she had enclosed three fleas. This is the only letter in which Leeuwenhoek mentions his maid assisting him.56 Leeuwenhoek’s flee project ran over several months in which Leeuwenhoek was experimenting with fleas so that he could understand their process of generation. The glass tubes were used specifically

52. AdB, Letter 93 (10 June 1686). 53. In this case Leeuwenhoek was asking for the observation of his draughtsman because he wanted to prove that the animal was already present in the seed, a theory debated over centuries. 54. AdB, Letter 126 (15 October 1683): “Fig. 6. ASTV. vertoont het Popke voor soo veel het den Teikenaar in de tweede afteikening heeft kunnen navolgen.” 55. Idem: “Ende alhoewel voornamentlijk in de buyk seer veel bloet-vaten te sien waren, soo heeft hy maar eenige weinige konnen aanhalen, seggende dat de andere onmoglijk waren te volgen.” 56. The maid (dienstmaagt) is mentioned twice in this letter, on pp. 220–21 and 238–39.

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Figure 26. Unknown engraver of period 2, Pupa of ﬂee as far as draughtsman was able to depict it, in Antoni van Leeuwenhoek, Vierde vervolg der brieven, 1693. Etching. 90 × 50 mm. London, Royal Society archives, EL/L2/44 (detail). (Photo © The Royal Society).

to observe the ﬂeas copulating. While the maid was supposed to capture the largest ﬂeas in the glass tubes, the draughtsman was given another task: A few days before, I had given the Copperplate Engraver two different glass tubes, to enclose therein some male and female Fleas

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from his Dog (which was infested with many ﬂeas), in order that he might see the copulation and thus might have a better notion when drawing it. But although he attempted this up to six times, each time with freshly caught Fleas, yet he had not succeeded in it. (AdB, 9:252–53)57 From this letter it becomes very clear that Leeuwenhoek did not work alone. He let his maid assist him, and he gave his draughtsman assign- ments for the improvement of their observations with the goal of better visual results.58 Towards the end of his life, Leeuwenhoek was even more explicit about the use of his draughtsman as the second witness to his experiments. He recounted the reasons the aforementioned painter, who had been drawing his observations for several years, arrived at his comptoir: “I don’t stand on my own, but have him as my second witness (“een tweede ooggetuijgen”), and also because he is of good judgment, and he can see sharper than I can at my high age.”59 Hence, at the end of his life, Leeuwenhoek made use of his draughtsman as his extra pair of eyes. Not only to draw his observations, not even only to act as second witness, but the draughtsman was asked to judge, since Leeuwenhoek’s most pre- cious instruments for observing, his own eyes, were getting old. Leeuwenhoek’s draughtsmen were his collaborators in observing, in seeing what the new world of microscopic observation would disclose. They were also the people who would tell Leeuwenhoek that some things could not be seen (“na te volgen”) and could therefore not be drawn, such as the blood vessels in the abdomen of the ﬂea. And in many ways, they were the ones determining the constraints of visually communicating his observations. Leeuwenhoek clearly enjoyed working with them, asking them what they thought they were seeing and sharing the moments of wonder when discovering ever-smaller structures of life. What is more, by incorporating the observations and practices of the draughtsmen into the accounts of his

57. AdB, Letter 126 (15 October 1683): “Ik hadde de Plaat-snyder eenige dagen hier te voren twee distincte glaasjens gegeven, om daar in op te sluiten van sijn Hont (die met veel Vloon was versien) eenige soo mannekens als wijfjens Vloon, om dat hy de versameling mogte sien, ende dus een beter concept in ’t afteikenen te hebben. Dog schoon hy al tot sesmaal toe sulks yder maal met vers gevangen Vloon hadde in ’t werk gestelt, soo en was het hem egter niet gelukt.” 58. For literature on the house and the household as site of experiment see Leong (2018). 59. Unpublished letter, Royal Society archives EL/L4/63/004 (24 January 1721): “Met dese mijne waarneminge besig sijnde, komt de konst schilder die ik sedert verscheijde jaaren mijne ontdekkinge hebbe laaten teijkenen, in mijn oog, die ik tot mij laat koomen om dat ik op mijn selven niet en soude staan, maar als een tweede ooggetuijgen hebben en ten anderen om dat van een goet oordeel is, en ook scharper kan sien als ik, in mijn seer hooge jaaren.” English translation my own.

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scientiﬁc practices, Leeuwenhoek created a similar event to the meetings of the Royal Society. It was not just him observing nature, but others were there with him to conﬁrm and discuss. The space of his comptoir became in this way a small replica of the Society’s weekly meetings, where Leeuwenhoek was partaking in collaborative research.

7. Printed Images Among the letters Leeuwenhoek sent to the Royal Society we do not only find drawings, but also printed images. Thirty-four of his letters in the Royal Society archives are currently kept with printed images, of which twelve letters contain printed images from the Philosophical Transactions and the Philosophical Collections. Both these journals (the latter was run for several years by Robert Hooke) contained printed images which were made after drawings or prints that were sent to the Royal Society and that the editor thought worthy of reproducing. This means that the editor would have employed engravers to cut the copper plates for him. The images in the twelve letters in the Leeuwenhoek correspondence that now contain printed images from the journals and from which the original drawings are lost, were thus added later, after they had been published, or at least after they had been cut for publication in London. Leeuwenhoek must have sent his own drawings or prints to London, after which the journal images would have been copied. Of the 223 letters he sent to the Royal Society between 1673 and 1723, 113 of them were (partially) printed in 116 articles in the journals.60 However, the publications of his letters are far from equally spread over these fifty years. The Philosophical Transactions was a journal started by the Society’s first Secretary, Oldenburg, as his privately funded journal. It was only in 1752 that the Royal Society took over the financial and editorial responsibility. Until that time the editor bore that burden (Moxham 2015, pp. 241–60). The fact that the journal was a personal enterprise and not a societal one had an impact on what was published and what was not. This is directly visible in the long list of published articles written by Leeuwenhoek. After Oldenburg’s death in 1677, Robert Hooke took over as Secretary of the Society as well as the editor of the journal, but instead of continuing the Philosophical Transactions, he sought to replace the journal with his own Philosophical Collections. Both Oldenburg and Hooke were favorable towards Leeuwenhoek (the first starting up the conversation, the second proposing Leeuwenhoek as a Fellow of the Royal Society) and they published articles based on his letters on a regular basis. This practice continued when the two

60. See Anderson, for more statistics on Leeuwenhoek’s letters: https://lensonleeuwenhoek. net/content/letters (last accessed 3 April 2018).

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Secretaries Robert Plot FRS and William Musgrave FRS collectively re- launched the Philosophical Transactions in 1683. However, with the start of Edmond Halley’s editorship (as a paid clerk between 1686 and 1692, and later as secretary from 1714 to 1719), the journal did not publish any letters by Leeuwenhoek. Instead, Halley published a substantial amount of his own work within the journal (Moxham 2015, p. 246). Most of Leeuwenhoek’s articles were published while Hans Sloane FRS and James Jurin FRS were secretaries and editors, between 1695 and 1713, and 1720 and 1723, respectively. What seems to be general practice amongst all these editors was to omit information about who made the images for Leeuwenhoek’sletters.Looking at the published version of Leeuwenhoek’s letter from 12 January 1680, with which he sent several drawings of the vessels of wood (see fig. 11), and in which he explained the copying process of the images, we find that this information is cut out. The drawing is no longer “drawn by me as well as possible,” but simply “drawn” (AdB, 3:150–51; Leeuwenhoek 1683, 199).61 Taking into account the fact that the published version of the image is no longer hand-drawn by Leeuwenhoek, this change in the translation of the text is technically correct.62 But it also means that authorship of the drawings (or the engravings for that matter) was not seen as essential information for the understanding and use of the images. A footnote in the journal article explained that “the Figures as they are graved are not so big as those designed by the Authour” (Leeuwenhoek 1683, p. 198). Specific comments like this on the transfer of images from drawings to printed engravings are rare. But in contrast to the insignifi- cance of the name of the maker, it shows an awareness of the text in which Leeuwenhoek described the scale of the drawings with regards to the size of the tree trunk, which was no longer valid with the change of image size. Despite the anonymity of the image-makers, comments about the draughtsmen who had been ordered to draw something Leeuwenhoek observed were often kept, even though many of Leeuwenhoek’s letters were publishedintranslationandinanabbreviatedform(see,forexample, Leeuwenhoek 1701). The publication of Leeuwenhoek’s letters in the Phil- osophical Transactions can be read as a history of the interest in his work by the editors of the journal, which, as we have seen, did not necessarily agree with the interests of the Society as a whole. And the process of publishing

61. AdB, Letter 54 (12 January 1680). 62. Leeuwenhoek sent most of his letters in Dutch (and some in Latin), which were then translated into English before they were discussed in the meetings and published in the Phil- osophical Transactions (Henderson 2013; Vermij and Palm 1992). See also Anderson (last accessed on 23 February 2019), https://lensonleeuwenhoek.net/content/leeuwenhoeks-translators.

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the drawings that Leeuwenhoek sent with his letters relied on a process of double translation, first of all the textual translations from Dutch to English, and subsequently the translation of the drawings to engravings. Leeuwenhoek also published many of his letters (including many images) himself. He published 165 of his letters in total, of which ninety were addressed to the Royal Society and its Fellows. It might have been due to the unpredictability of the editors’ willingness to publish Leeuwenhoek’s letters, or the irregular pace of publication. Whatever the reason, Leeuwenhoek started to look into other possibilities for getting his ideas in print, and from 1684 onwards he started to publish some of his letters himself. Twelve letters by Leeuwenhoek in the archives of the Royal Society contain printed images from the Philosophical Transactions. The other twenty- two archived letters with printed images, however, contain images that were printed in the Netherlands under the instructions of Leeuwenhoek himself. As we have seen above, Leeuwenhoek did refer to his draughtsmen, and on rare occasions also to his “plaat-snyder,” a copper-plate cutter or engraver.63 In the four letters in which he mentions engravers, he also mentioned draughtsmen (teijkenaars), seemingly interchangeably, which makes it difficult to know whether he had two different people working for him, a draughtsman and an engraver, or whether this could have been one and the same person. He certainly used the verb “afteikenen” (to draw) also in the context of the engraver. It is not impossible that it was the same person making both drawings and engravings. As with the drawings, it is very likely there were several people involved in the production of the engravings for Leeuwenhoek’s publications, which appeared over a period of thirty-five years, between 1684 and 1719. On the basis of the way the abbreviated word “figure” was engraved in all the printed images, it seems possible to distinguish again three periods of engravers. The first engraver continuously engraved the plates between 1684 and 1689. The lower loops of the “f ” and the “g” almost always went back through the downward leg, creating an egg shape (fig. 27).64 The second period started with the 1693 publication of Derde vervolg der brieven and ended with the 1702 Sevende vervolg de brieven. The engraver of this period liked his elaborations on the three letters he got to play with, as can be seen in figure 28, and there is always at least one “Fig” with some additional loops, like “Figs” 2, 7, and 11 in this figure. The engraver changed his letters slightly over the

63. Leeuwenhoek mentioned copper-plate cutters in four letters: Letter 126 (15 October 1693); Letter 134 (2 March 1684); Letter 136 (2 April 1694); and Letter 157 (18 September 1695), which was not addressed to the Royal Society but to Johann Wilhelm von Pfalz-Neuburg. 64. I am using the numbering system of Leeuwenhoek’s publications as devised by Dobell (1932, pp. 392–97). This ﬁrst engraver’s period covers all publications from 1 to 12.

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Figure 27. Abraham de Blois, Trachea system and silkworm egg, in Antoni van Leeuwenhoek, Vervolg de brieven, 1687. Etching. 78 × 114 mm. London, Royal Society archives, EL/L2/13. (Photo The Royal Society).

Figure 28. Unknown engraver of period 2, Observations of salt particles in pepper, and tea, in Antoni van Leeuwenhoek, Derde vervolg der brieven, 1693. Engraving. 97 × 136 mm. London, Royal Society archives, EL/L2/31. (Photo © The Royal Society).

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period. Especially the lower loop of the “g” lost its loop more and more, but the change is easy to follow from one engraving to the other.65 The third and final period was marked by only one publication, the 1718 Send-brieven and its Latin translation in 1719. This engraver was, like the first, more consistent in his engraving of the “Fig” (fig. 29). Since Boitet described Willem vander Wilt as the maker of plates for Leeuwenhoek’s works, we can assume here that Vander Wilt was indeed the draughtsman and the plate cutter during the final years of Leeuwenhoek’s career. All three periods run wonderfully parallel to the three periods of draughtsmen, which makes it tempting to assume that it was not only in the last period that there was just one person performing the roles of both draughtsman and cutter. The first period of draughtsmen was characterized by many different hands, so there were certainly more people working for Leeuwenhoek in that period. Nevertheless, and due to the consistency in the cutting of “Fig” in the engravings of the first period, we may assume that this engraver was Abraham de Blois. As we have seen before, he was mentioned as the engraver of the images in the first publication of Leeuwenhoek letters in the Netherlands (Leeuwenhoek 1684, Opdragt). Whether he was also one of the draughtsmen of the first period stays unsolved. The second period might have been the work of one draughtsman and cutter, or of two different artists. Leeuwenhoek published his letters not only in Dutch, but also in Latin translation.66 On top of that, many of his publications had second, third, and fourth editions during his lifetime, and they were published by six different publishers, split equally between Delft and Leiden.67 My research into the various editions in both Dutch and Latin has shown that the copper plates with the images were always the same between the Dutch and the Latin versions, as well as between the various editions. This means that the plates were cut only once, and that they were kept carefully throughout Leeuwenhoek’s life. Most of these plates seem to have been kept by the publishers and not by Leeuwenhoek himself. This becomes evident from his 1721 will, in which Leeuwenhoek mentioned specifically the only ten copper plates and letters still in his possession (Beydals 1933, p. 1029). His only surviving daughter, Maria Thonis (1656–1745), still possessed these plates at the time of her death, according to the inventory that was made up after her death (Zuidervaart and Anderson 2016, pp. 23–24).

65. Dobell publications 13–18. 66. Antoni van Leeuwenhoek hired people to translate his letters into Latin. We know that Hans van Rijn translated the 46 letters of the Send-brieven for the Latin Epistolae Physiologicae (1719), as well as several unpublished letters that remained in the estate of Leeuwenhoek after his death (Oudheden en Gestichten 1725, p. 726; Catalogus 1747). 67. On the publishers, see the pages by Douglas Anderson, https://lensonleeuwenhoek. net/content/booksellers (last accessed 6 August 2018).

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Leeuwenhoek published his own letters with images, especially during the periods that the editors of the Philosophical Transactions were not par- ticularly keen on the publication of his letters. But how did the images from the Dutch and Latin editions end up in the Royal Society archives? Leeuwenhoek explained to Richard Waller, who was Secretary of the Royal Society at the time, in a letter of 8 December 1693: That I am sending these observations to the Royal Society in print, and not in written form, is done for no other reason than that it is troublesome for me to write out once again what I have already written, and I hope that this method will be approved of. (AdB, 9:266–67)68 From this letter, entirely dedicated to the receiving and sending of letters, we can infer that Leeuwenhoek sent his letters in printed form to the Royal Society. Clearly this is how some of the images printed in the Netherlands ended up in the archives in London. And it does happen, although not regularly, that these already printed letters and their images were re-published in the Philosophical Transactions.Thismeantthattheimageswereoncemore cut into a copper plate, but this time in London (see ﬁgs. 30 and 31).

8. Conclusions This close analysis of the drawings and prints in the Leeuwenhoek correspondence gives us a much clearer view of Leeuwenhoek’s visual practices. His visual collections consist of drawings now kept in the Royal Society archives, as well as printed images in those archives and in the journals related to the early Royal Society and in Leeuwenhoek’s own publications. We have been able to distinguish hands amongst the draughtsmen and engravers, which enables us to connect the already known name of Willem Vander Wilt to the drawings and engravings during the final eleven years of Leeuwenhoek’s life. Leeuwenhoek used his draughtsmen for much more than purely record- ing his observations. They became his witnesses, his collaborators, and towards the end of his life, his eyes. The study of Leeuwenhoek’svisual heritage has shown that he was not just working on his own in his comptoir, relying on friends and colleagues to bring him rare specimens to observe under his microscope. Quite the contrary. Leeuwenhoek conducted collaborative work during his fifty years of correspondence, initiated by Oldenburg’s request for images after his first letter. Leeuwenhoek was the lead researcher, but his visual heritage and the discoveries he communicated through his images were a team effort.

68. AdB, Letter 128 (8 December 1693).

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